[ { "anchor": "Star formation activities in early-type brightest cluster galaxies: We identify a total of 120 early-type Brightest Cluster Galaxies (BCGs) at\n0.13 in the MUSE\neXtremely Deep Field with a mass of $10^9$ M$_{\\odot}$. In addition to very\nstrong Lyman-$\\alpha$ (Ly$\\alpha$) emission, we clearly detect the (stellar)\ncontinuum and an NV P-Cygni feature, interstellar absorption, fine-structure\nemission and nebular CIV emission lines in the 140 hr spectrum. Continuum\nemission from two spatially resolved components in Hubble Space Telescope data\nare blended in the MUSE data, but we show that the nebular CIV emission\noriginates from a subcomponent of the galaxy. The UV spectrum can be fit with\nrecent BPASS stellar population models combined with single-burst or continuous\nstar formation histories (SFHs), a standard initial mass function, and an\nattenuation law. Models with a young age and low metallicity\n(log10(age/yr)=6.5-7.6 and [Z/H]=-2.15 to -1.15) are preferred. The intrinsic\nH$\\alpha$ luminosity of the best-fit models is an order of magnitude higher\nthan the H$\\alpha$ luminosity inferred from Spitzer/IRAC data, which either\nsuggests a high escape fraction of ionising photons, a high relative\nattenuation of nebular to stellar dust, or a complex SFH. The metallicity\nappears lower than the metallicity in more massive galaxies at z=3-5,\nconsistent with the scenario according to which younger galaxies have lower\nmetallicities. This chemical immaturity likely facilitates Ly$\\alpha$ escape,\nexplaining why the Ly$\\alpha$ equivalent width is anti-correlated with stellar\nmetallicity. Finally, we stress that uncertainties in SFHs impose a challenge\nfor future inferences of the stellar metallicity of young galaxies. This\nhighlights the need for joint (spatially resolved) analyses of stellar spectra\nand photo-ionisation models." }, { "anchor": "Chemical Abundances of Planetary Nebulae in the Substructures of M31 --\n II. The Extended Sample and A Comparison Study with the Outer-disk Group: We report deep spectroscopy of ten planetary nebulae (PNe) in the Andromeda\nGalaxy (M31) using the 10.4m GTC. Our targets reside in different regions of\nM31, including halo streams and dwarf satellite M32, and kinematically deviate\nfrom the extended disk. The temperature-sensitive [O III] 4363 auroral line is\nobserved in all targets. For four PNe, the GTC spectra extend beyond 1 micron,\nenabling explicit detection of the [S III] 6312 and 9069,9531 lines and thus\ndetermination of the [S III] temperature. Abundance ratios are derived and\ngenerally consistent with AGB model predictions. Our PNe probably all evolved\nfrom low-mass (<2 M_sun) stars, as analyzed with the most up-to-date post-AGB\nevolutionary models, and their main-sequence ages are mostly ~2-5 Gyr. Compared\nto the underlying, smooth, metal-poor halo of M31, our targets are uniformly\nmetal-rich ([O/H]> -0.4), and seem to resemble the younger population in the\nstream. We thus speculate that our halo PNe formed in the Giant Stream's\nprogenitor through extended star formation. Alternatively, they might have\nformed from the same metal-rich gas as did the outer-disk PNe, but was\ndisplaced into their present locations as a result of galactic interactions.\nThese interpretations are, although speculative, qualitatively in line with the\ncurrent picture, as inferred from previous wide-field photometric surveys, that\nM31's halo is the result of complex interactions and merger processes. The\nbehavior of N/O of the combined sample of the outer-disk and our\nhalo/substructure PNe signifies that hot bottom burning might actually occur at\n<3 M_sun, but careful assessment is needed.", "positive": "Cosmic evolution of radio-AGN feedback: confronting models with data: Radio-mode feedback is a key ingredient in galaxy formation and evolution\nmodels, required to reproduce the observed properties of massive galaxies in\nthe local Universe. We study the cosmic evolution of radio-AGN feedback out to\n$z\\sim2.5$ using a sample of 9485 radio-excess AGN. We combine the evolving\nradio luminosity functions with a radio luminosity scaling relationship to\nestimate AGN jet kinetic powers and derive the cosmic evolution of the kinetic\nluminosity density, $\\Omega_{\\rm{kin}}$ (i.e. the volume-averaged heating\noutput). Compared to all radio-AGN, low-excitation radio galaxies (LERGs)\ndominate the feedback activity out to $z\\sim2.5$, with both these populations\nshowing a constant heating output of $\\Omega_{\\rm{kin}} \\approx 4-5 \\times\n10^{32}\\,\\rm{W\\,Mpc^{-3}}$ across $0.5 < z < 2.5$. We compare our observations\nto predictions from semi-analytical and hydrodynamical simulations, which\nbroadly match the observed evolution in $\\Omega_{\\rm{kin}}$, although their\nabsolute normalisation varies. Comparison to the Semi-Analytic Galaxy Evolution\n(SAGE) model suggests that radio-AGN may provide sufficient heating to offset\nradiative cooling losses, providing evidence for a self-regulated AGN feedback\ncycle. We integrate the kinetic luminosity density across cosmic time to obtain\nthe kinetic energy density output from AGN jets throughout cosmic history to be\n$\\sim 10^{50}\\,\\rm{J\\,Mpc^{-3}}$. Compared to AGN winds, the kinetic energy\ndensity from AGN jets dominates the energy budget at $z \\lesssim 2$; this\nsuggests that AGN jets play an important role in AGN feedback across most of\ncosmic history." }, { "anchor": "The rest-frame optical (900nm) galaxy luminosity function at z~4-7:\n abundance matching points to limited evolution in the Mstar/Mhalo ratio at\n z>4: We present the first determination of the galaxy luminosity function (LF) at\nz~4, 5, 6 and 7 in the rest-frame optical at lambda_rest~900 nm (z' band). The\nrest-frame optical light traces the content in low-mass evolved stars (~stellar\nmass - Mstar), minimizing potential measurement biases for Mstar. Moreover it\nis less affected by nebular line emission contamination and dust attenuation,\nis independent of stellar population models, and can be probed up to z~8\nthrough Spitzer/IRAC. Our analysis leverages the unique full depth Spitzer/IRAC\n3.6um-to-8.0um data over the CANDELS/GOODS-N, CANDELS/GOODS-S and\nCOSMOS/UltraVISTA fields. We find that at absolute magnitudes M_z' fainter than\n>-23 mag, M_z' linearly correlates with M_UV,1600. At brighter M_z', M_UV,1600\npresents a turnover, suggesting that the stellar mass-to-light ratio\nMstar/L_UV,1600 could be characterised by a very broad range of values at high\nstellar masses. Median-stacking analysis recovers a Mstar/L_z' roughly\nindependent on M_z' for M_z'>-23 mag, but exponentially increasing at brighter\nmagnitudes. We find that the evolution of the LF marginally prefers a pure\nevolution in luminosity over a pure evolution in density, with the\ncharacteristic luminosity decreasing by a factor ~5x between z~4 and z~7.\nDirect application of the recovered Mstar/L_z' generates stellar mass functions\nconsistent with average measurements from the literature. Measurements of the\nstellar-to-halo mass ratio at fixed cumulative number density show that it is\nroughly constant with redshift for Mh>10^12Msun. This is also supported by the\nfact that the evolution of the LF at 40.2$ and $(z_s/D_{25,ph}\\times100)<0.2$,\nrespectively. The former is named as \"high-group\" and the latter is named as\n\"low-group.\" We conclude that \"high-group\" is likely to be the galaxies with\nsubstantial extraplanar dust, while \"low-group\" is likely to be the ones with\nlittle extraplanar dust, i.e. typical galactic thin disk, based on the\nfollowing points: (1) the relative positions of \"high-group\" and \"low-group\" on\nthe plot $z_s/D_{25,ph}$ vs $z_d/D_{25,ph}$ with respect to the reference\nvalues from optical radiative transfer studies; (2) the lower scale-height of\nthe young stellar population than the old stellar population; and (3) a test\nresult that shows the existence of extraplanar dust makes $z_s$ and $z_d$\noverestimated in the fitting results. We also examined the dependence of the\ngroup separation on the surface density of far-ultraviolet luminosity\n($L_{FUV}/D^2_{25,ph}$), but found no strong dependence." }, { "anchor": "Early results from GLASS-JWST. XIV: A spectroscopically confirmed\n protocluster 650 million years after the Big Bang: We present the spectroscopic confirmation of a protocluster at $z=7.88$\nbehind the galaxy cluster Abell2744 (hereafter A2744-z7p9OD). Using JWST\nNIRSpec, we find seven galaxies within a projected radius of 60kpc. Although\nthe galaxies reside in an overdensity around $>20\\times$ greater than a random\nvolume, they do not show strong Lyman-alpha emission. We place 2-$\\sigma$ upper\nlimits on the rest-frame equivalent width $<16$-$28$AA. Based on the tight\nupper limits to the Lyman-alpha emission, we constrain the volume-averaged\nneutral fraction of hydrogen in the intergalactic medium to be $x_{\\rm HI} >\n0.45$ (68% CI). Using an empirical $M_{\\rm UV}$-$M_{\\rm halo}$ relation for\nindividual galaxies, we estimate that the total halo mass of the system is\n$\\gtrsim 4\\times10^{11}\\,M_\\odot$. Likewise, the line of sight velocity\ndispersion is estimated to be $1100 \\pm 200$km/s. Using an empirical relation,\nwe estimate the present-day halo mass of A2744-z7p9OD to be\n$\\sim2\\times10^{15}\\,M_\\odot$, comparable to the Coma cluster. A2744-z7p9OD is\nthe highest redshift spectroscopically confirmed protocluster to date,\ndemonstrating the power of JWST to investigate the connection between\ndark-matter halo assembly and galaxy formation at very early times with\nmedium-deep observations at $<20$hrs total exposure time. Follow-up\nspectroscopy of the remaining photometric candidates of the overdensity will\nfurther refine the features of this system and help characterize the role of\nsuch overdensities in cosmic reionization.", "positive": "The Galactic Extinction Horizon with Present and Future Surveys: We have made a lot of progress in the study of the MW. In spite of this, much\nof our Galaxy remains unknown, and amazing breakthroughs await to be made in\nthe exploration of the far side of the Galaxy. Focussing on the Galactic\nextinction horizon problem with current surveys like the Two Micron All-Sky\nSurvey (2MASS) and the Vista Variables in the Via Lactea Survey (VVV) and its\nextension VVVX, the extinction horizon is a fundamental difficulty, and it is\nmy intention here to reveal how profound is our ignorance, and also to try to\nsuggest ways for improvement with future near-IR Galactic surveys." }, { "anchor": "Decoupled gas kinematics in isolated S0 galaxies: A sample of completely isolated S0 galaxies has been studied by means of\nlong-slit spectroscopy at the Russian 6-m telescope. 7 of 12 galaxies have\nrevealed a presence of extended ionized-gas discs which rotation is mostly\ndecoupled from the stellar kinematics: 5 of 7 (71+/-17%) galaxies show a\nvisible counterrotation of the ionized-gas component with respect to the\nstellar component. The emission-line diagnostics demonstrates a wide range of\nthe gas excitation mechanisms, although a pure excitation by young stars is\nrare. We conclude that in all cases the extended gaseous discs in our sample\nS0s are of external origin, despite the visible isolation of the galaxies.\nPossible sources of external accretion, such as systems of dwarf gas-rich\nsatellites or cosmological cold-gas filaments, are discussed.", "positive": "The Magellanic Stream: Circumnavigating the Galaxy: The Magellanic Clouds are surrounded by an extended network of gaseous\nstructures. Chief among these is the Magellanic Stream, an interwoven tail of\nfilaments trailing the Clouds in their orbit around the Milky Way. When\nconsidered in tandem with its Leading Arm, the Stream stretches over 200\ndegrees on the sky. Thought to represent the result of tidal interactions\nbetween the Clouds and ram-pressure forces exerted by the Galactic corona, its\nkinematic properties reflect the dynamical history of the closest pair of dwarf\ngalaxies to the Milky Way. The Stream is a benchmark for hydrodynamical\nsimulations of accreting gas and cloud/corona interactions. If the Stream\nsurvives these interactions and arrives safely in the Galactic disk, its cargo\nof over a billion solar masses of gas has the potential to maintain or elevate\nthe Galactic star formation rate. In this article, we review the current state\nof knowledge of the Stream, including its chemical composition, physical\nconditions, origin, and fate. We also review the dynamics of the Magellanic\nSystem, including the proper motions and orbital history of the Large and Small\nMagellanic Clouds, the first-passage and second-passage scenarios, and the\nevidence for a Magellanic Group of galaxies." }, { "anchor": "A Supernova-driven, Magnetically-collimated Outflow as the Origin of the\n Galactic Center Radio Bubbles: A pair of non-thermal radio bubbles recently discovered in the inner few\nhundred parsecs of the Galactic center bears a close spatial association with\nelongated, thermal X-ray features called the X-ray chimneys. While their\nmorphology, position, and orientation vividly point to an outflow from the\nGalactic center, the physical processes responsible for the outflow remain to\nbe understood. We use three-dimensional magnetohydrodynamic simulations to test\nthe hypothesis that the radio bubbles/X-ray chimneys are the manifestation of\nan energetic outflow driven by multiple core-collapsed supernovae in the\nnuclear stellar disk, where numerous massive stars are known to be present. Our\nsimulations are run with different combinations of two main parameters, the\nsupernova birth rate and the strength of a global magnetic field being\nvertically oriented with respect to the disk. The simulation results show that\na hot gas outflow can naturally form and acquire a vertically elongated shape\ndue to collimation by the magnetic pressure. In particular, the simulation with\nan initial magnetic field strength of 80 $\\mu$G and a supernova rate of 1\n$kyr^{-1}$ can well reproduce the observed morphology, internal energy and\nX-ray luminosity of the bubbles after an evolutionary time of 330 kyr. On the\nother hand, a magnetic field strength of 200 $\\mu$G gives rise to an overly\nelongated outflow that is inconsistent with the observed bubbles. The\nsimulations also reveal that, inside the bubbles, mutual collisions between the\nshock waves of individual supernovae produce dense filaments of locally\namplified magnetic field. Such filaments may account for a fraction of the\nsynchrotron-emitting radio filaments known to exist in the Galactic center.", "positive": "Evolution of the anti-truncated stellar profiles of S0 galaxies since\n $z=0.6$ in the SHARDS survey: I - Sample and Methods: The controversy about the origin of the structure of S0--E/S0 galaxies may be\ndue to the difficulty of comparing surface brightness profiles with different\ndepths, photometric corrections and PSF effects (almost always ignored). We aim\nto quantify the properties of Type-III (anti-truncated) discs in a sample of S0\ngalaxies at 0.2 3$. Adopting realistic values for\ngalactic and intergalactic opacity, the estimates of the EBL for the expanding\ndusty universe are close to observations. The luminosity density evolution fits\nwell measurements. The model reproduces a steep increase of the luminosity\ndensity at $z<2$, its maximum at $z=2-3$, and its decrease at higher redshifts.\nThe increase of the luminosity density at low $z$ is not produced by the\nevolution of the star formation rate but by the fact that the Universe occupied\na smaller volume in previous epochs. The decline of the luminosity density at\nhigh $z$ originates in the opacity of the Universe. The calculated bolometric\nEBL ranges from 100 to 200 $\\mathrm{n W m}^{-2}\\mathrm{sr}^{-1}$ and is within\nthe limits of 40 and 200 $\\mathrm{n W m}^{-2}\\mathrm{sr}^{-1}$ of current EBL\nobservations. The model predicts 98\\% of the EBL coming from radiation of\ngalaxies at $z<3.5$. Accounting for light extinction by intergalactic dust\nimplies that the Universe was probably more opaque than dark for $z>3.5$." }, { "anchor": "Revisiting the Mass-Excitation (MEx) diagram using the MaNGA dataset: The diagram comparing the flux ratio of the [OIII] and H$\\beta$ emission\nlines with the total stellar mass of galaxies (also known as the\nmass-excitation diagram, MEx) has been widely used to classify the ionization\nmechanism in high redshift galaxies between star formation and active galactic\nnuclear ones. This diagram was mainly derived using single-fiber spectroscopy\nfrom the SDSS-DR7 survey. In this study, we revise this diagram using the\ncentral and integrated spectral measurement from the entire Integral Field\nSpectroscopic MaNGA sample. Our results suggest that along with the physical\nparameters of this diagram, the equivalent width of the H$\\alpha$ emission line\nis also required to constrain the ionization mechanism of a high-redshifted\ngalaxy. Furthermore, the location of a galaxy in the excitation-mass diagram\nvaries depending on the use of central or integrated properties.", "positive": "The Star Forming Main Sequence of Dwarf Low Surface Brightness Galaxies: We explore the star forming properties of late type, low surface brightness\n(LSB) galaxies. The star forming main sequence (SFR-$M_*$) of LSB dwarfs has a\nsteep slope, indistinguishable from unity ($1.04 \\pm 0.06$). They form a\ndistinct sequence from more massive spirals, which exhibit a shallower slope.\nThe break occurs around $M_* \\approx 10^{10}\\;M_{\\odot}$, and can also be seen\nin the gas mass-stellar mass plane. The global Kennicutt-Schmidt law\n(SFR-$M_g$) has a slope of $1.47 \\pm 0.11$ without the break seen in the main\nsequence. There is an ample supply of gas in LSB galaxies, which have gas\ndepletion times well in excess of a Hubble time, and often tens of Hubble\ntimes. Only $\\sim 3\\%$ of this cold gas need be in the form of molecular gas to\nsustain the observed star formation. In analogy with the faint, long-lived\nstars of the lower stellar main sequence, it may be appropriate to consider the\nmain sequence of star forming galaxies to be defined by thriving dwarfs (with\n$M_* < 10^{10}\\;M_{\\odot}$) while massive spirals (with $M_* >\n10^{10}\\;M_{\\odot}$) are weary giants that constitute more of a turn-off\npopulation." }, { "anchor": "A high-resolution spectroscopic analysis of aminoacrylonitrile and an\n interstellar search towards G+0.693: Cyanides, ranging from three carbon atoms to PAHs, and alkenyl compounds are\nabundant in the interstellar medium (ISM). Aminoacrylonitrile\n(3-Amino-2-propenenitrile, H$_{2}$N-CH=CH-CN), an alkenyl cyanide, thus\nrepresents a promising candidate for new interstellar detection. A\ncomprehensive spectroscopic laboratory investigation of aminoacrylonitrile in\nits rotational ground vibrational state has been herein performed. The\nmeasurements carried out up to the THz regime made it possible to generate a\nprecise set of reliable rest frequencies for its search in space up to\nsub-millimetre wavelengths. The $Z$-aminoacrylonitrile ($Z$-apn) isomer\nspectrum has been recorded employing a source-modulated sub-millimetre\nspectrometer, from 80 GHz to 1 THz. A combination of Doppler and sub-Doppler\nmeasurement regimes allowed to record 600 new lines. The collected data have\nenabled the characterisation of a set of spectroscopic parameters up to decic\ncentrifugal distortion constants. The catalogue generated from the improved\nspectral data has been used for the search of $Z$-apn in the spectral survey of\nthe G+0.693-0.027 molecular cloud located in the central molecular zone, in the\nproximity of the Galactic centre.", "positive": "Digging for red nuggets: discovery of hot halos surrounding massive,\n compact, relic galaxies: We present the results of Chandra X-ray observations of the isolated,\nmassive, compact, relic galaxies MRK 1216 and PGC 032873. Compact massive\ngalaxies observed at z>2, also called red nuggets, formed in quick dissipative\nevents and later grew by dry mergers into the local giant ellipticals. Due to\nthe stochastic nature of mergers, a few of the primordial massive galaxies\navoided the mergers and remained untouched over cosmic time. We find that the\nhot atmosphere surrounding MRK 1216 extends far beyond the stellar population\nand has an 0.5-7 keV X-ray luminosity of $L_{\\rm X}=(7.0\\pm0.2)\\times10^{41}$\nerg s$^{-1}$, which is similar to the nearby X-ray bright giant ellipticals.\nThe hot gas has a short central cooling time of $\\sim50$ Myr and the galaxy has\na $\\sim13$ Gyr old stellar population. The presence of an X-ray atmosphere with\na short nominal cooling time and the lack of young stars indicate the presence\nof a sustained heating source, which prevented star formation since the\ndissipative origin of the galaxy 13 Gyrs ago. The central temperature peak and\nthe presence of radio emission in the core of the galaxy indicate that the\nheating source is radio-mechanical AGN feedback. Given that both MRK 1216 and\nPGC 032873 appear to have evolved in isolation, the order of magnitude\ndifference in their current X-ray luminosity could be traced back to a\ndifference in the ferocity of the AGN outbursts in these systems. Finally, we\ndiscuss the potential connection between the presence of hot halos around such\nmassive galaxies and the growth of super/over-massive black holes via chaotic\ncold accretion." }, { "anchor": "Probing the roles of orientation and multi-scale gas distributions in\n shaping the obscuration of Active Galactic Nuclei through cosmic time: The origin of obscuration in Active Galactic Nuclei (AGN) is still an open\ndebate. In particular, it is unclear what drives the relative contributions to\nthe line-of-sight column densities from galaxy-scale and torus-linked\nobscuration. The latter source is expected to play a significant role in\nUnification Models, while the former is thought to be relevant in both\nUnification and Evolutionary Models. In this work, we make use of a combination\nof cosmological semi-analytic models and semi-empirical prescriptions for the\nproperties of galaxies and AGN, to study AGN obscuration. We consider a\ndetailed object-by-object modelling of AGN evolution, including different AGN\nlight curves (LCs), gas density profiles, and also AGN feedback-induced gas\ncavities. Irrespective of our assumptions on specific AGN LC or galaxy gas\nfractions, we find that, on the strict assumption of an exponential profile for\nthe gas component, galaxy-scale obscuration alone can hardly reproduce the\nfraction of $\\log (N_{\\rm H}/$cm$^{-2}) \\geq 24$ sources at least at\n$z\\lesssim3$. This requires an additional torus component with a thickness that\ndecreases with luminosity to match the data. The torus should be present in all\nevolutionary stages of a visible AGN to be effective, although galaxy-scale gas\nobscuration may be sufficient to reproduce the obscured fraction with $22<\\log\n(N_{\\rm H}/$cm$^{-2})<24$ (Compton-thin, CTN) if we assume extremely compact\ngas disc components. The claimed drop of CTN fractions with increasing\nluminosity does not appear to be a consequence of AGN feedback, but rather of\ngas reservoirs becoming more compact with decreasing stellar mass.", "positive": "The Lyman-alpha luminosity function at z=5.7-6.6 and the steep drop of\n the faint end: implications for reionization: We present new results from the widest narrow band survey search for\nLyman-alpha (Lya) emitters at z=5.7, just after reionization. We survey a total\nof 7 deg$^2$ spread over the COSMOS, UDS and SA22 fields. We find over 11,000\nline emitters, out of which 514 are robust Lya candidates at z=5.7 within a\nvolume of 6.3x10$^6$ Mpc$^3$. Our Lya emitters span a wide range in Lya\nluminosities, from faint to bright (L$_{\\rm Ly\\alpha}\\sim10^{42.5-44}$ erg\ns$^{-1}$) and rest-frame equivalent widths (EW$_0$~25-1000 \\AA) in a single,\nhomogeneous data-set. By combining all our fields we find that the faint end\nslope of the z=5.7 Lya luminosity function is very steep, with\n$\\alpha=-2.3^{+0.4}_{-0.3}$. We also present an updated z=6.6 Lya luminosity\nfunction, based on comparable volumes and obtained with the same methods, which\nwe directly compare with that at z=5.7. We find a significant decline of the\nnumber density of faint Lya emitters from z=5.7 to z=6.6 (by $0.5\\pm0.1$ dex),\nbut no evolution at the bright end/no evolution in L*. Faint Lya emitters at\nz=6.6 show much more extended haloes than those at z=5.7, suggesting that\nneutral Hydrogen plays an important role, increasing the scattering and leading\nto observations missing faint Lya emission within the epoch of reionization.\nAll together, our results suggest that we are observing patchy reionization\nwhich happens first around the brightest Lya emitters, allowing the number\ndensities of those sources to remain unaffected by the increase of neutral\nHydrogen fraction from z~5 to z~7." }, { "anchor": "Searching for local counterparts of high-redshift post-starburst\n galaxies in integral field unit spectroscopic surveys of nearby galaxies: Searching in the MaNGA IFU survey, I identify 9 galaxies that have strong\nBalmer absorption lines and weak nebular emission lines measured from the\nspectra integrated over the entire IFUs. The spectral features measured from\nthe bulk of the stellar light make these galaxies local analogs of\nhigh-redshift spectroscopically-selected post-starburst galaxies, thus, proxies\nto understand the mechanisms producing post-starburst galaxies at\nhigh-redshifts. I present the distributions of absorption-line indices and\nemission-line strengths, as well as stellar kinematics of these local\npost-starburst galaxies. Almost all local post-starburst galaxies have central\ncompact emission-line regions at the central $<1$ kpc, mostly powered by weak\nstar-formation activities. The age-sensitive absorption line indices\nEW(H$\\delta$) and Dn4000 indicate that the stellar populations at the outskirts\nare older. Toy stellar population synthesis models suggest that the entire\ngalaxies are experiencing a rapid decline of star formation with residual\nstar-formation activities at the centers. These features demand that most\npost-starburst galaxies are the aftermath of highly dissipative processes that\ndrive gas into centers, invoke centrally-concentrated star formation, then\nquench the galaxies. Meanwhiles, when measurable, post-starburst galaxies have\nthe directions of maximum stellar velocity gradients align with photometric\nmajor axes, which suggest against major mergers being the principal driving\nmechanism, while gas-rich minor mergers are plausible. While directly obtaining\nthe same quality of spatially-resolved spectra of high-redshift post-starburst\ngalaxies is very difficult, finding proper local counterparts provides an\nalternative to understand quenching processes in the distant Universe.", "positive": "The helium content of globular clusters: NGC6121 (M4): He has been proposed as a key element to interpret the observed multiple MS,\nSGB, and RGB, as well as the complex horizontal branch (HB) morphology. Stars\nbelonging to the bluer part of the HB, are thought to be more He rich (\\Delta\nY=0.03 or more) and more Na-rich/O-poor than those located in the redder part.\nThis hypothesis was only partially confirmed in NGC 6752, where stars of the\nredder zero-age HB showed a He content of Y=0.25+-0.01, fully compatible with\nthe primordial He content of the Universe, and were all Na-poor/O-rich. Here we\nstudy hot blue HB (BHB) stars in the GC NGC 6121 (M4) to measure their He plus\nO/Na content. We observed 6 BHB stars using the UVES@VLT2 spectroscopic\nfacility. In addition to He, O, Na, and Fe abundances were estimated. Stars\nturned out to be all Na-rich and O-poor and to have a homogeneous enhanced He\ncontent with a mean value of Y=0.29+-0.01(random)+-0.01(systematic). The high\nHe content of blue HB stars in M4 is also confirmed by the fact that they are\nbrighter than red HB stars (RHB). Theoretical models suggest the BHB stars are\nHe-enhanced by \\Delta Y=0.02-0.03 with respect to the RHB stars. The whole\nsample of stars has a metallicity of [Fe/H]=-1.06+-0.02 (internal error). This\nis a rare direct measurement of the (primordial) He abundance for stars\nbelonging to the Na-rich/O-poor population of GC stars in a temperature regime\nwhere the He content is not altered by sedimentation or extreme mixing as\nsuggested for the hottest, late helium flash HB stars. Our results support\ntheoretical predictions that the Na-rich/O-poor population is also more He-rich\nthan the Na-poor/O-rich generation and that a leading contender for the 2^{nd}\nparameter is the He abundance." }, { "anchor": "A Molecular Gas Ring Hidden in the Sombrero Galaxy: We present Herschel, ALMA, and MUSE observations of the molecular ring of\nMessier 104, also known as the Sombrero galaxy. These previously unpublished\narchival data shed new light on the content of the interstellar medium of M104.\nIn particular, molecular hydrogen measured by CO emission and dust measured by\nfar-infrared light are uniformly distributed along the ring. The ionized gas\nrevealed by H$\\alpha$ and [CII] emission is distributed in knots along the\nring. Despite being classified as an SAa galaxy, M104 displays features typical\nof early-type galaxies. We therefore compared its [CII] and dust emission to a\nsample of early-type galaxies observed with Herschel and SOFIA. The [CII]/FIR\nratio of M104 is much lower than that of typical star-forming galaxies and is\ninstead much more similar to that of early-type galaxies. By classifying\nregions using optical emission line diagnostics we also find that regions\nclassified as HII lie closer to star-forming galaxies in the [CII]/FIR diagram\nthan those classified as low-ionization emission regions. The good match\nbetween [CII] and H$\\alpha$ emission in conjunction with the lack of\ncorrelation between CO emission and star formation suggest that there is very\nlimited active star formation along the ring and that most of the [CII]\nemission is from ionized and neutral atomic gas rather than molecular gas. From\nthe total intensity of the CO line we estimate a molecular hydrogen mass of\n0.9$\\times10^9$M$_{\\odot}$, a value intermediate between those of early type\ngalaxies and the content of the molecular ring of our galaxy.", "positive": "Warped Disk Galaxies. I. Linking U type Warps in Groups/Clusters to\n Jellyfish Galaxies: arped disk galaxies are classified into two morphologies: S- and U-types.\nConventional theories routinely attribute both types to galactic tidal\ninteraction and/or gas accretion, but reproducing of U-types in simulations is\nextremely challenging. Here we investigate whether both types are governed by\nthe same mechanisms using the most extensive sample of $\\sim$8000 nearby\n(0.02\\,$<$\\,z\\,$<$\\,0.06) massive ($M_{*}/M_{\\odot}$\\,$>$\\,$10^9$) edge-on\ndisks from SDSS. We find that U-types show on average bluer optical colors and\nhigher specific star formation rate (sSFR) than S-types, with more strongly\nwarped U-types having higher sSFR. We also find that while the S-type warp\nproperties correlate with the tidal force by the nearest neighbor regardless of\nthe environment, there is no such correlation for U-types in groups/clusters,\nsuggesting a non-tidal environmental could be at play for U-types, such as ram\npressure stripping (RPS). Indeed, U-types are more common in groups/clusters\nthan in fields and they have stellar mass, gas fraction, sSFR enhancement and\nphase-space distribution closely analogous to RPS-induced jellyfish galaxies in\nclusters. We furthermore show that the stellar disks of most RPS galaxies in\nthe IllustirsTNG simulation are warped in U-shape and bent in opposite\ndirection of stripped gas tails, satisfying theoretical expectations for\nstellar warps embeded in jellyfishes. We therefore suggest that despite the\nmajority of U-types that live in fields being still less explained, RPS can be\nan alternative origin for those in groups/clusters." }, { "anchor": "The small scatter of the baryonic Tully-Fisher relation: In a LCDM cosmology, the baryonic Tully-Fisher relation (BTFR) is expected to\nshow significant intrinsic scatter resulting from the mass-concentration\nrelation of dark matter halos and the baryonic-to-halo mass ratio. We study the\nBTFR using a sample of 118 disc galaxies (spirals and irregulars) with data of\nthe highest quality: extended HI rotation curves (tracing the outer velocity)\nand Spitzer photometry at 3.6 $\\mu$m (tracing the stellar mass). Assuming that\nthe stellar mass-to-light ratio (M*/L) is nearly constant at 3.6 $\\mu$m, we\nfind that the scatter, slope, and normalization of the BTFR systematically vary\nwith the adopted M*/L. The observed scatter is minimized for M*/L > 0.5,\ncorresponding to nearly maximal discs in high-surface-brightness galaxies and\nBTFR slopes close to ~4. For any reasonable value of M*/L, the intrinsic\nscatter is ~0.1 dex, below general LCDM expectations. The residuals show no\ncorrelations with galaxy structural parameters (radius or surface brightness),\ncontrary to the predictions from some semi-analytic models of galaxy formation.\nThese are fundamental issues for LCDM cosmology.", "positive": "Asymmetric Drift Map of the Milky Way disk Populations between 8$-$16\n kpc with LAMOST and Gaia datasets: The asymmetric drift (AD) tomography in different populations will be helpful\nfor us to better understand the disk kinematics, dynamics and rotation curves.\nUsing the common stars from the LAMOST and Gaia surveys as well as circular\nvelocity of Gaia DR3, we qualitatively explore the asymmetric drift\ndistribution of the Galactic disk from 8$-$16 \\,kpc. In the $R-Z$ plane, we\nfind the asymmetric drift near the plane of the Galactic disk is small, and\nthen gradually increases with the increase of the vertical distance, which\nmakes the asymmetric drift appear as a ``horn\" shape in the $R-Z$ plane.\nMeanwhile, we reveal that high [$\\alpha$/Fe] populations have larger asymmetric\ndrift than that in the low [$\\alpha$/Fe] populations. The asymmetric drift\naround the solar location V$_a$ = 6 km s$^{-1}$ and the asymmetric drift median\nvalue of the whole sample is 16 km s$^{-1}$. Moreover, we also find that the\nasymmetric drift median value in the north (20 km s$^{-1}$) of the Galactic\ndisk is larger than that in the south (13 km s$^{-1}$), all errors are within 2\nkm s$^{-1}$. Furthermore, when we investigate the asymmetric drift of the\nGalactic disk in the mono-age stellar populations, we also find that the older\nstellar populations have larger asymmetric drift and velocity dispersion which\nis consistent with predictions of previous numerical models. Finally, based on\nthe chemistry, we unveil that the average asymmetric drift of the thick disk is\nmuch higher than that of the thin disk." }, { "anchor": "The ALMA-ALPINE [CII] survey: Kennicutt-Schmidt relation in four massive\n main-sequence galaxies at z~4.5: The Kennicutt-Schmidt (KS) relation between the gas and the star formation\nrate (SFR) surface density ($\\Sigma_{\\rm gas}$-$\\Sigma_{\\rm SFR}$) is essential\nto understand star formation processes in galaxies. So far, it has been\nmeasured up to z~2.5 in main-sequence galaxies. In this letter, we aim to put\nconstraints at z~4.5 using a sample of four massive main-sequence galaxies\nobserved by ALMA at high resolution. We obtained ~0.3\"-resolution [CII] and\ncontinuum maps of our objects, which we then converted into gas and obscured\nSFR surface density maps. In addition, we produced unobscured SFR surface\ndensity maps by convolving Hubble ancillary data in the rest-frame UV. We then\nderived the average $\\Sigma_{\\rm SFR}$ in various $\\Sigma_{\\rm gas}$ bins, and\nestimated the uncertainties using a Monte Carlo sampling. Our galaxy sample\nfollows the KS relation measured in main-sequence galaxies at lower redshift\nand is slightly lower than predictions from simulations. Our data points probe\nthe high end both in terms of $\\Sigma_{\\rm gas}$ and $\\Sigma_{\\rm gas}$, and\ngas depletion timescales (285-843 Myr) remain similar to z~2 objects. However,\nthree of our objects are clearly morphologically disturbed, and we could have\nexpected shorter gas depletion timescales (~100 Myr) similar to merger-driven\nstarbursts at lower redshifts. This suggests that the mechanisms triggering\nstarbursts at high redshift may be different than in the low- and\nintermediate-z Universe.", "positive": "The elusive tidal tails of the Milky Way globular cluster NGC 7099: We present results on the extra-tidal features of the Milky Way globular\ncluster NGC 7099, using deep gr photometry obtained with the Dark Energy Camera\n(DECam). We reached nearly 6 mag below the cluster Main Sequence (MS) turnoff,\nso that we dealt with the most suitable candidates to trace any stellar\nstructure located beyond the cluster tidal radius. From star-by-star reddening\ncorrected color-magnitude diagrams (CMDs) we defined four adjacent strips along\nthe MS, for which we built the respective stellar density maps, once the\ncontamination by field stars was properly removed. The resulting field star\ncleaned stellar density maps show a short tidal tail and some scattered debris.\nSuch extra-tidal features are hardly detected when much shallower Gaia DR2 data\nsets are used and the same CMD field star cleaning procedure is applied.\nIndeed, by using 2.5 magnitudes below the cluster MS turnoff as the faintest\nlimit (G < 20.5 mag), cluster members turned out to be distributed within the\ncluster's tidal radius, and some hints for field star density variations are\nfound across a circle of radius 3.5deg centered on the cluster and with similar\nCMD features as cluster stars. The proper motion distribution of these stars is\ndistinguishable from that of the cluster, with some superposition, which\nresembles that of stars located beyond 3.5deg from the cluster center." }, { "anchor": "Milliarcsecond structure and variability of methanol maser emission in\n three high-mass protostars: {The variability study of 6.7\\,GHz methanol masers has become a useful way to\nimprove our understanding of the physical conditions in high-mass star-forming\nregions.} {Based on the single-dish monitoring using the Irbene telescopes, we\nselected three sources with close sky positions.} {We imaged them using the\nEuropean Very Long Baseline Interferometer Network and searched available data\non VLBI archives to follow detailed changes in their structures and single\nmaser spot variability.} {All three targets show a few groups of maser\ncloudlets of a typical size of 3.5\\,mas and the majority of them show linear or\narched structures with velocity gradients of order 0.22\\kms\\,mas$^{-1}$. The\ncloudlets and overall source morphologies are remarkably stable on time scales\nof 7-15\\,yr supporting a scenario of variability due to changes in the maser\npumping rate.}", "positive": "The Kelvin-Helmholtz instability in weakly ionised plasmas II:\n multifluid effects in molecular clouds: We present a study of the Kelvin-Helmholtz instability in a weakly ionised,\nmultifluid MHD plasma with parameters matching those of a typical molecular\ncloud. The instability is capable of transforming well-ordered flows into\ndisordered flows. As a result, it may be able to convert the energy found in,\nfor example, bowshocks from stellar jets into the turbulent energy found in\nmolecular clouds. As these clouds are weakly ionised, the ideal\nmagnetohydrodynamic approximation does not apply at scales of around a tenth of\na parsec or less. This paper extends the work of Jones & Downes (2011) on the\nevolution of the Kelvin-Helmholtz instability in the presence of multifluid\nmagnetohydrodynamic effects. These effects of ambipolar diffusion and the Hall\neffect are here studied together under physical parameters applicable to\nmolecular clouds. We restrict our attention to the case of a single shear layer\nwith a transonic, but super-Alfvenic, velocity jump and the computational\ndomain is chosen to match the wavelength of the linearly fastest growing mode\nof the instability.\n We find that while the introduction of multifluid effects does not affect the\nlinear growth rates of the instability, the non-linear behaviour undergoes\nconsiderable change. The magnetic field is decoupled from the bulk flow as a\nresult of the ambipolar diffusion, which leads to a significant difference in\nthe evolution of the field. The Hall effect would be expected to lead to a\nnoticeable re-orientation of the magnetic field lines perpendicular to the\nplane. However, the results reveal that the combination with ambipolar\ndiffusion leads to a surprisingly effective suppression of this effect." }, { "anchor": "Understanding the shape and diversity of dwarf galaxy rotation curves in\n LCDM: The shape and diversity of dwarf galaxy rotation curves is at apparent odds\nwith dark matter halos in a $\\Lambda$ Cold Dark Matter ($\\Lambda$CDM)\ncosmology. We use mock data from isolated dwarf galaxy simulations to show that\nthis owes to three main effects. Firstly, stellar feedback heats dark matter,\nleading to a 'coreNFW' dark matter density profile with a slowly rising\nrotation curve. Secondly, if close to a recent starburst, large HI bubbles push\nthe rotation curve out of equilibrium, deforming the rotation curve shape.\nThirdly, when galaxies are viewed near face-on, their best fit inclination is\nbiased high. This can lead to a very shallow rotation curve that falsely\nimplies a large dark matter core. All three problems can be avoided, however,\nby a combination of improved mass models and a careful selection of target\ngalaxies. Fitting our coreNFW model to mock rotation curve data, we show that\nwe can recover the rotation curve shape, dark matter halo mass $M_{200}$ and\nconcentration parameter $c$ within our quoted uncertainties.\n We fit our coreNFW model to real data for four isolated dwarf irregulars,\nchosen to span a wide range of rotation curve shapes. We obtain an excellent\nfit for NGC 6822 and WLM, with tight constraints on $M_{200}$, and $c$\nconsistent with $\\Lambda$CDM. However, IC 1613 and DDO 101 give a poor fit. For\nIC 1613, we show that this owes to disequilibria and its uncertain inclination\n$i$; for DDO 101, it owes to its uncertain distance $D$. If we assume $i_{\\rm\nIC1613} \\sim 15^\\circ$ and $D_{\\rm DDO101} \\sim 12$ Mpc, consistent with\ncurrent uncertainties, we are able to fit both galaxies very well. We conclude\nthat $\\Lambda$CDM appears to give an excellent match to dwarf galaxy rotation\ncurves.", "positive": "Revised gas-phase formation network of methyl cyanide: the origin of\n methyl cyanide and methanol abundance correlation in hot corinos: Methyl cyanide (CH$_3$CN) is one of the most abundant and widely spread\ninterstellar complex organic molecules (iCOMs). Several studies found that, in\nhot corinos, methyl cyanide and methanol abundances are correlated suggesting a\nchemical link, often interpreted as a synthesis of them on the interstellar\ngrain surfaces. In this article, we present a revised network of the reactions\nforming methyl cyanide in the gas-phase. We carried out an exhaustive review of\nthe gas-phase CH$_3$CN formation routes, propose two new reactions and\nperformed new quantum mechanics computations of several reactions. We found\nthat 13 of the 15 reactions reported in the databases KIDA and UDfA have\nincorrect products and/or rate constants. The new corrected reaction network\ncontains 10 reactions leading to methyl cyanide. We tested the relative\nimportance of those reactions in forming CH$_3$CN using our astrochemical\nmodel. We confirm that the radiative association of CH${_3}{^+}$ and HCN,\nforming CH$_{3}$CNH$^{+}$, followed by the electron recombination of\nCH$_{3}$CNH$^{+}$, is the most important CH$_3$CN formation route in both cold\nand warm environments, notwithstanding that we significantly corrected the rate\nconstants and products of both reactions. The two newly proposed reactions play\nan important role in warm environments. Finally, we found a very good agreement\nbetween the CH$_3$CN predicted abundances with those measured in cold ($\\sim$10\nK) and warm ($\\sim$90 K) objects. Unexpectedly, we also found a chemical link\nbetween methanol and methyl cyanide via the CH$_{3}^{+}$ ion, which can explain\nthe observed correlation between the CH$_3$OH and CH$_3$CN abundances measured\nin hot corinos." }, { "anchor": "A family of potential-density pairs for galactic bars: We present a family of analytical potential-density pairs for barred discs,\nwhich can be combined to describe galactic bars in a realistic way, including\nboxy/peanut components. We illustrate this with two reasonable compound models.\nComputer code for the evaluation of potential, forces, density, and projected\ndensity is freely provided.", "positive": "Interpreting the sub-linear Kennicutt-Schmidt relationship: The case for\n diffuse molecular gas: Recent statistical analysis of two extragalactic observational surveys\nstrongly indicate a sublinear Kennicutt-Schmidt (KS) relationship between the\nstar formation rate (Sigsfr) and molecular gas surface density (Sigmol). Here,\nwe consider the consequences of these results in the context of common\nassumptions, as well as observational support for a linear relationship between\nSigsfr and the surface density of dense gas. If the CO traced gas depletion\ntime (tau_mol) is constant, and if CO only traces star forming giant molecular\nclouds (GMCs), then the physical properties of each GMC must vary, such as the\nvolume densities or star formation rates. Another possibility is that the\nconversion between CO luminosity and Sigmol, the XCO factor, differs from\ncloud-to-cloud. A more straightforward explanation is that CO permeates the\nhierarchical ISM, including the filaments and lower density regions within\nwhich GMCs are embedded. A number of independent observational results support\nthis description, with the diffuse gas comprising at least 30% of the total\nmolecular content. The CO bright diffuse gas can explain the sublinear KS\nrelationship, and consequently leads to an increasing tau_mol with Sigmol. If\nSigsfr linearly correlates with the dense gas surface density, a sublinear KS\nrelationship indicates that the fraction of diffuse gas fdiff grows with\nSigmol. In galaxies where Sigmol falls towards the outer disk, this description\nsuggests that fdiff also decreases radially." }, { "anchor": "On the triggering of extreme starburst events in low-metallicity\n galaxies: a deep search for companions of Green Peas: Green pea galaxies are starbursting, low-mass galaxies that are good\nanalogues to star-forming galaxies in the early universe. We perform a survey\nof 23 Green Peas using the MUSE Integral Field Unit spectrograph on the VLT to\nsearch for companion galaxies. The survey reaches an average point-source depth\nof $\\sim 10^{-18}$ erg cm$^{-2}$ s$^{-1}$ for emission lines. The MUSE field of\nview allows us to probe a 1$\\times$1 arcmin$^2$ field around these galaxies and\nto search their surroundings for faint companions that could have interacted\nwith them and induced their starburst episodes. We search for companions using\na variety of methods including template matching to emission and absorption\nline spectra. When restricting the search to the same physical area (R = 78\nkpc) for all galaxies, we find that the fraction of green pea galaxies with\ncompanions is $0.11_{-0.05}^{+0.07}$. We define a control sample of\nstar-forming galaxies with the same stellar masses and redshifts as the green\npeas, but consistent with the star-formation main sequence. We find that green\npea galaxies are as likely to have companions as the control sample; for which\nthe fraction of objects with companions is $0.08_{-0.03}^{+0.05}$. Given that\nwe do not find statistical evidence for an elevated companion fraction in the\ngreen peas in this study, we argue that the ``companions\" are likely unrelated\nto the bursts in these galaxies.", "positive": "The Globular Cluster Population of NGC 1052-DF2: Evidence for Rotation: Based upon the kinematics of ten globular clusters, it has recently been\nclaimed that the ultra-diffuse galaxy, NCD 1052-DF2, lacks a significant\nquantity of dark matter. Dynamical analyses have generally assumed that this\ngalaxy is pressure supported, with the relatively small velocity dispersion of\nthe globular cluster population indicating the deficit of dark matter. However,\nthe presence of a significant rotation of the globular cluster population could\nsubstantially modify this conclusion. Here we present the discovery of such a\nsignature of rotation in the kinematics of NGC 1052-DF2's globular clusters,\nwith a velocity amplitude of $\\sim12.44^{+4.40}_{-5.16}$ km/s, which, through\nBayesian model comparison, represents a marginally better fit to the available\nkinematic data; note that this rotation is distinct from, and approximately\nperpendicular to, the recently identified rotation of the stellar component of\nNGC 1052-DF2. Assuming this truly represents an underlying rotation, it is\nshown that the determined mass depends upon the inclination of the rotational\ncomponent and, with a moderate inclination, the resultant mass to light ratio\ncan exceed $M/L\\sim10$." }, { "anchor": "ALMA CO Clouds and Young Star Complexes in the Interacting Galaxies IC\n 2163 and NGC 2207: ALMA observations of CO(1-0) emission in the interacting galaxies IC 2163 and\nNGC 2207 are used to determine the properties of molecular clouds and their\nassociation with star-forming regions observed with the Hubble Space Telescope.\nHalf of the CO mass is in 249 clouds each more massive than 4.0x10^5Mo. The\nmass distribution functions for the CO clouds and star complexes in a\ngalactic-scale shock front in IC 2163 both have a slope on a log-log plot of\n-0.7, similar to what is observed in Milky Way clouds. The molecular cloud mass\nfunction is steeper in NGC 2207. The CO distribution in NGC 2207 also includes\na nuclear ring, a mini-bar, and a mini-starburst region that dominates the\n24micron, radio, and Halpha emission in both galaxies. The ratio of the sum of\nthe masses of star complexes younger than 30 Myr to the associated molecular\ncloud masses is ~4%. The maximum age of star complexes in the galactic-scale\nshock front in IC 2163 is about 200 Myr, the same as the interaction time of\nthe two galaxies, suggesting the destruction of older complexes in the eyelids.", "positive": "Self-Gravitating Relativistic Models of Fermions with Anisotropy and\n Cutoff Energy in their Distribution Function: In this paper we study the equilibrium configurations of anisotropic\nself-gravitating fermions, by extending to general relativity the solutions\nobtained in a previous paper. This treatment also generalizes to anisotropic\nsystems the relativistic self-gravitating Fermi gas model, by considering\ndifferent degrees of anisotropy. We discuss some important characteristics of\nthe models and the obtained density profiles, and generalize the relation\nbetween the anisotropy and the mass of particles in the relativistic regime.\nThese relativistic models may also be applied to the study of superdense\nneutron stars with anisotropic pressure or super-Chandrasekhar white dwarfs\ngenerated by the presence of a magnetic field." }, { "anchor": "Dust and Gas environment of the young embedded cluster IRAS 18511+0146: IRAS 18511+0146 is a young embedded (proto)cluster located at 3.5 kpc\nsurrounding what appears to be an intermediate mass protostar. In this paper,\nwe investigate the nature of cluster members (two of which are believed to be\nthe most massive and luminous) using imaging and spectroscopy in the near and\nmid-infrared. The brightest point-like object associated with IRAS 18511+0146\nis referred to as S7 in the present work (designated UGPS J185337.88+015030.5\nin the UKIRT Galactic Plane survey). Seven of the nine objects show rising\nspectral energy distributions (SED) in the near-infrared, with four objects\nshowing Br-gamma emission. Three members: S7, S10 (also UGPS\nJ185338.37+015015.3) and S11 (also UGPS J185338.72+015013.5) are bright in\nmid-infrared with diffuse emission being detected in the vicinity of S11 in PAH\nbands. Silicate absorption is detected towards these three objects, with an\nabsorption maximum between 9.6 and 9.7 um, large optical depths (1.8-3.2), and\nprofile widths of 1.6-2.1 um. The silicate profiles of S7 and S10 are similar,\nin contrast to S11 (which has the largest width and optical depth). The cold\ndust emission investigated using Herschel HiGal peaks at S7, with temperature\nat 26 K and column density N(H2) ~ 7 x 10^(22) cm^(-2). The bolometric\nluminosity of IRAS 18511 region is L ~ 1.8 x 10^4 L_sun. S7 is the main\ncontributor to the bolometric luminosity, with L (S7) > 10^4 L_sun. S7 is a\nhigh mass protostellar object with ionised stellar winds, evident from the\ncorrelation between radio and bolometric luminosity as well as the asymmetric\nBr-gamma profile. The differences in silicate profiles of S7 and S11 could be\ndue to different radiation environment as we believe the former to be more\nmassive and in an earlier phase than the latter.", "positive": "A Magnetic Ribbon Model for Star-Forming Filaments: We develop a magnetic ribbon model for molecular cloud filaments. These\nresult from turbulent compression in a molecular cloud in which the background\nmagnetic field sets a preferred direction. We argue that this is a natural\nmodel for filaments and is based on the interplay between turbulence, strong\nmagnetic fields, and gravitationally-driven ambipolar diffusion, rather than\npure gravity and thermal pressure. An analytic model for the formation of\nmagnetic ribbons that is based on numerical simulations is used to derive a\nlateral width of a magnetic ribbon. This differs from the thickness along the\nmagnetic field direction, which is essentially the Jeans scale. We use our\nmodel to calculate a synthetic observed relation between apparent width in\nprojection versus observed column density. The relationship is relatively flat,\nsimilar to observations, and unlike the simple expectation based on a Jeans\nlength argument." }, { "anchor": "XID+ a new prior-based extraction tool for Herschel-SPIRE maps: We present XID+ a new generation of software for prior-based photometry\nextraction in the Herschel SPIRE maps. Based on a Bayesian framework, XID+\nallows the inclusion of prior information and gives access to the full\nposterior probability distribution of fluxes. XID+ is developed within the\nHerschel Extragalactic Legacy Project (HELP) and is available at\nhttps://github.com/H-E-L-P/XID_plus.", "positive": "Gaia Early Data Release 3: Structure and properties of the Magellanic\n Clouds: We compare the Gaia DR2 and Gaia EDR3 performances in the study of the\nMagellanic Clouds and show the clear improvements in precision and accuracy in\nthe new release. We also show that the systematics still present in the data\nmake the determination of the 3D geometry of the LMC a difficult endeavour;\nthis is at the very limit of the usefulness of the Gaia EDR3 astrometry, but it\nmay become feasible with the use of additional external data.\n We derive radial and tangential velocity maps and global profiles for the LMC\nfor the several subsamples we defined. To our knowledge, this is the first time\nthat the two planar components of the ordered and random motions are derived\nfor multiple stellar evolutionary phases in a galactic disc outside the Milky\nWay, showing the differences between younger and older phases. We also analyse\nthe spatial structure and motions in the central region, the bar, and the disc,\nproviding new insights into features and kinematics.\n Finally, we show that the Gaia EDR3 data allows clearly resolving the\nMagellanic Bridge, and we trace the density and velocity flow of the stars from\nthe SMC towards the LMC not only globally, but also separately for young and\nevolved populations. This allows us to confirm an evolved population in the\nBridge that is slightly shift from the younger population. Additionally, we\nwere able to study the outskirts of both Magellanic Clouds, in which we\ndetected some well-known features and indications of new ones." }, { "anchor": "Feeding Versus Feedback in NGC1068 probed with Gemini NIFS. I.\n Excitation: We present emission-line flux distributions and ratios for the inner 200pc of\nthe narrow-line region of the Seyfert2 galaxy NGC1068, using observations\nobtained with the Gemini Near-infrared Integral Field Spectrograph (NIFS) in\nthe J, H and K bands at a spatial resolution of 10pc and spectral resolution of\n5300. The molecular gas emission - traced by the K-band H_2 emission lines -\noutlines an off-centered circumnuclear ring with a radius of 100pc showing\nthermal excitation. The ionized gas emission lines show flux distributions\nmostly outlining the previously known [OIII]5007 ionization bicone. But while\nthe flux distributions in the HI and HeII emission lines are very similar to\nthat observed in [OIII], the flux distribution in the [FeII] emission lines is\nmore extended and broader than a cone close to the nucleus, showing a \"double\nbowl\" or `hourglass\" structure\". This difference is attributed to the fact that\nthe [FeII] emission, besides coming from the fully ionized region, comes also\nfrom the more extended partially ionized regions, in gas excited mainly by\nX-rays from the active galactic nucleus. A contribution to the [FeII] emission\nfrom shocks along the bicone axis to NE and SW of the nucleus is also supported\nby the enhancement of the [FeII](1.2570)/[PII](1.1885) and\n[FeII](1.2570)/Pabeta emission-line ratios at these locations and is attributed\nto the interaction of the radio jet with the NLR. The mass of ionized gas in\nthe inner 200pc of NGC1068 is MHII~2.2E4 M_Sun, while the mass of the H2\nemitting gas is only M_{H2}~29M_Sun. Taking into account the dominant\ncontribution of the cold molecular gas, we obtain an estimate of the total\nmolecular gas mass of Mcold~2E7 M_Sun.", "positive": "P-MaNGA: Gradients in Recent Star Formation Histories as Diagnostics for\n Galaxy Growth and Death: We present an analysis of the data produced by the MaNGA prototype run\n(P-MaNGA), aiming to test how the radial gradients in recent star formation\nhistories, as indicated by the 4000AA-break (D4000), Hdelta absorption\n(EW(Hd_A)) and Halpha emission (EW(Ha)) indices, can be useful for\nunderstanding disk growth and star formation cessation in local galaxies. We\nclassify 12 galaxies observed on two P-MaNGA plates as either centrally\nquiescent (CQ) or centrally star-forming (CSF), according to whether D4000\nmeasured in the central spaxel of each datacube exceeds 1.6. For each galaxy we\ngenerate both 2D maps and radial profiles of D4000, EW(Hd_A) and EW(Ha). We\nfind that CSF galaxies generally show very weak or no radial variation in these\ndiagnostics. In contrast, CQ galaxies present significant radial gradients, in\nthe sense that D4000 decreases, while both EW(Hd_A) and EW(Ha) increase from\nthe galactic center outward. The outer regions of the galaxies show greater\nscatter on diagrams relating the three parameters than their central parts. In\nparticular, the clear separation between centrally-measured quiescent and\nstar-forming galaxies in these diagnostic planes is largely filled in by the\nouter parts of galaxies whose global colors place them in the green valley,\nsupporting the idea that the green valley represents a transition between\nblue-cloud and red-sequence phases, at least in our small sample. These results\nare consistent with a picture in which the cessation of star formation\npropagates from the center of a galaxy outwards as it moves to the red\nsequence." }, { "anchor": "Star Formation of Merging Disk Galaxies with AGN Feedback Effects: Using numerical hydrodynamics code, we perform various idealized galaxy\nmerger simulations to study the star formation (SF) of two merging disk\ngalaxies. Our simulations include gas accretion onto supermassive black holes\nand active galactic nucleus (AGN) feedback. By comparing AGN simulations with\nthose without AGNs, we attempt to understand when the AGN feedback effect is\nsignificant. With ~70 simulations, we investigated the SF with the AGN effect\nin mergers with variety of mass ratios, inclinations, orbits, galaxy structures\nand morphologies. Using these merger simulations with AGN feedback, we measure\nmerger-driven SF using the burst efficiency parameter introduced by Cox et al.\nWe confirm the previous studies that, in galaxy mergers, AGN suppresses SF more\nefficiently than in isolated galaxies. However, we additionally find that the\neffect of AGNs on SF is larger in major mergers than in minor mergers. In minor\nmerger simulations with different primary bulge-to-total ratios, the effect of\nbulge fraction on the merger-driven SF decreases due to AGN feedback. We create\nmodels of Sa, Sb and Sc type galaxies and compare their SF properties while\nundergoing mergers. With the current AGN prescriptions, the difference in\nmerger-driven SF is not as pronounced as that in the recent observational study\nof Kaviraj. We discuss the implications of this discrepancy.", "positive": "A Survey for High-redshift Gravitationally Lensed Quasars and Close\n Quasars Pairs. I. the Discoveries of an Intermediately-lensed Quasar and a\n Kpc-scale Quasar Pair at $z\\sim5$: We present the first results from a new survey for high-redshift\n$(z\\gtrsim5)$ gravitationally lensed quasars and close quasar pairs. We carry\nout candidate selection based on the colors and shapes of objects in public\nimaging surveys, then conduct follow-up observations to confirm the nature of\nhigh-priority candidates. In this paper, we report the discoveries of\nJ0025--0145 ($z=5.07$) which we identify as an {intermediately-lensed quasar,\nand J2329--0522 ($z=4.85$) which is a kpc-scale close quasar pair. The {\\em\nHubble Space Telescope (HST)} image of J0025--0145 shows a foreground lensing\ngalaxy located $0\\farcs6$ away from the quasar. However, J0025--0145 does not\nexhibit multiple lensed images of the quasar, and we identify J0025--0145 as an\nintermediate lensing system (a lensing system that is not multiply imaged but\nhas a significant magnification). The spectrum of J0025--0145 implies an\nextreme Eddington ratio if the quasar luminosity is intrinsic, which could be\nexplained by a large lensing magnification. The {\\em HST} image of J0025--0145\nalso indicates a tentative detection of the quasar host galaxy in rest-frame\nUV, illustrating the power of lensing magnification and distortion in studies\nof high-redshift quasar host galaxies. J2329--0522 consists of two resolved\ncomponents with significantly different spectral properties, and a lack of\nlensing galaxy detection under sub-arcsecond seeing. We identify it as a close\nquasar pair, which is the highest confirmed kpc-scale quasar pair to date. We\nalso report four lensed quasars and quasar pairs at $2~100 Myr immediately following particularly extreme bursts of star formation\nduring the bursty phase. On the other hand, the best-fitting averaging\ntime-scale for H${\\alpha}$ is generally insensitive to the SFR variability in\nthe FIRE simulations and remains ~5 Myr at all times. These time-scales are\nshorter than the 100 Myr and 10 Myr time-scales sometimes assumed in the\nliterature for FUV and H${\\alpha}$, respectively, because while the FUV\nemission persists for stellar populations older than 100 Myr, the\ntime-dependent luminosities are strongly dominated by younger stars. Our\nresults confirm that the ratio of SFRs inferred using H${\\alpha}$ vs. FUV can\nbe used to probe the burstiness of star formation in galaxies.", "positive": "Project Overview of the Beijing-Arizona Sky Survey: The Beijing-Arizona Sky Survey (BASS) is a wide-field two-band photometric\nsurvey of the Northern Galactic Cap using the 90Prime imager on the 2.3 m Bok\ntelescope at Kitt Peak. It is a four-year collaboration between the National\nAstronomical Observatory of China and Steward Observatory, the University of\nArizona, serving as one of the three imaging surveys to provide photometric\ninput catalogs for target selection of the Dark Energy Spectroscopic Instrument\n(DESI) project. BASS will take up to 240 dark/grey nights to cover an area of\nabout 5400 deg$^2$ in the $g$ and $r$ bands. The 5$\\sigma$ limiting AB\nmagnitudes for point sources in the two bands, corrected for the Galactic\nextinction, are 24.0 and 23.4 mag, respectively. BASS, together with other DESI\nimaging surveys, will provide unique science opportunities that cover a wide\nrange of topics in both Galactic and extragalactic astronomy." }, { "anchor": "MONDian predictions for Newtonian M/L ratios for ultrafaint dSphs: Under Newtonian gravity total masses for dSph galaxies will scale as $M_{T}\n\\propto R_{e} \\sigma^{2}$, with $R_{e}$ the effective radius and $\\sigma$ their\nvelocity dispersion. When both of the above quantities are available, the\nresulting masses are compared to observed stellar luminosities to derive\nNewtonian mass to light ratios, given a physically motivated proportionality\nconstant in the above expression. For local dSphs and the growing sample of\nultrafaint such systems, the above results in the largest mass to light ratios\nof any galactic systems known, with values in the hundreds and even thousands\nbeing common. The standard interpretation is for a dominant presence of an as\nyet undetected dark matter component. If however, reality is closer to a\nMONDian theory at the extremely low accelerations relevant to such systems,\n$\\sigma$ will scale with { stellar mass} $M_{*}^{1/4}$. This yields an\nexpression for the mass to light ratio which will be obtained under Newtonian\nassumptions of $(M/L)_{N}=120 R_{e}(\\Upsilon_{*}/L)^{1/2}$. Here we compare\n$(M/L)_{N}$ values from this expression to Newtonian inferences for this ratios\nfor the actual $(R_{e}, \\sigma, L)$ observed values for a sample of recently\nobserved ultrafaint dSphs, obtaining good agreement. Then, for systems where no\n$\\sigma$ values have been reported, we give predictions for the $(M/L)_{N}$\nvalues which under a MONDian scheme are expected once kinematical observations\nbecome available. For the recently studied Dragonfly 44 { and Crater II\nsystems}, reported $(M/L)_{N}$ values are also in good agreement with MONDian\nexpectations.", "positive": "Estimating Dust Temperature and Far-IR Luminosity of High-Redshift\n Galaxies using ALMA Single-Band Continuum Observations: We present a method that derives the dust temperatures and infrared (IR)\nluminosities of high-redshift galaxies assuming radiation equilibrium in a\nsimple dust and stellar distribution geometry. Using public data from the\nAtacama Large Millimeter/submillimeter Array (ALMA) archive, we studied dust\ntemperatures assuming a clumpy interstellar medium (ISM) model for\nhigh-redshift galaxies, then tested the consistency of our results with those\nobtained using other methods. We find that a dust distribution model assuming a\nclumpiness of ${\\rm log}\\,\\xi_{\\rm clp}=-1.02\\pm0.41$ may accurately represent\nthe ISM of high-redshift star-forming galaxies. By assuming a value of\n$\\xi_{\\rm{clp}}$, our method enables the derivation of dust temperatures and IR\nluminosities of high-redshift galaxies from dust continuum fluxes and emission\nsizes obtained from single-band ALMA observations. to demonstrate the method\nproposed herein, we determined the dust temperature ($T_{\\rm\nd}=95^{+13}_{-17}\\,\\rm{K}$) of a $z\\sim8.3$ star-forming galaxy, MACS0416-Y1.\nBecause the method only requires a single-band dust observation to derive a\ndust temperature, it is more easily accessible than multi-band observations or\nhigh-redshift emission line searches and can be applied to large samples of\ngalaxies in future studies using high resolution interferometers such as ALMA." }, { "anchor": "The GOGREEN Survey: A deep stellar mass function of cluster galaxies at\n 1.040K in\nthe central 100pc to <15K at 250pc sampling the cooling of the molecular gas in\nthe outflow. We used three methods to derive alpha_CO in eight 100pc (0.5\")\napertures in the outflow by fitting the P(J+2)/R(J) ratios with non-LTE models.\nWe obtain low median alpha_CO factors (0.40-0.61) x 3.2e-4/[CO/H2] Msun (K\nkm/s/pc2)^-1 in the outflow regions. This implies that outflow rates and\nenergetics might be overestimated if a ULIRG-like alpha_CO, which is 1.3-2\ntimes larger, is assumed. The reduced alpha_CO can be explained if the\noutflowing molecular clouds are not virialized. We also report the first\nextragalactic detection of a broad (sigma=0.0091um) spectral feature at 4.645um\nassociated with aliphatic deuterium on polycyclic aromatic hydrocarbons\n(D_n-PAH).", "positive": "Cold HI ejected into the Magellanic Stream: We report the direct detection of cold HI gas in a cloud ejected from the\nSmall Magellanic Cloud (SMC) towards the Magellanic Stream. The cloud is part\nof a fragmented shell of HI gas on the outskirts of the SMC. This is the second\ndirect detection of cold HI associated with the Magellanic Stream using\nabsorption. The cold gas was detected using 21-cm HI absorption-line\nobservations with the Australia Telescope Compact Array (ATCA) towards the\nextra-galactic source PMN J0029$-$7228. We find a spin (excitation) temperature\nfor the gas of $68 \\pm 20$ K. We suggest that breaking super shells from the\nMagellanic Clouds may be a source of cold gas to supply the rest of the\nMagellanic Stream." }, { "anchor": "Characteristics of mid-infrared PAH emission from star-forming galaxies\n selected at 250 \u03bcm in the North Ecliptic Pole (NEP) field: Evolutionary properties of infrared (IR) luminous galaxies are important keys\nto understand dust-obscured star formation history and galaxy evolution. Based\non the near- to mid-IR imaging with 9 continuous filters of AKARI space\ntelescope, we present the characteristics of dusty star-forming (SF) galalxies\nshowing polycyclic aromatic hydrocarbon (PAH) features observed by the North\nEcliptic Pole (NEP) wide field survey of AKARI and Herschel. All the sample\ngalaxies from the AKARI/NEP-Wide data are selected based both on the\nHerschel/SPIRE 250 {\\mu}m detection and optical spectroscopic redshift data.\nThe physical modelling of spectral energy distribution (SED) using all\navailable data points from u to sub-mm 500 {\\mu}m band, including WISE and PACS\ndata where available, takes unique advantages of the continuous near to mid-IR\ncoverage, reliable constraint on far-IR peak, spectroscopically determined\naccurate redshifts, as well as energy balance principle by MAGPHYS. This\nenables us to derive physically meaningful and accurate total infrared\nluminosity and 8 {\\mu}m (or PAH) luminosity consistently. Our sample galaxies\nare in the redshift range z <1, and majority of them appear to be normal\nSF/spiral populations showing PAH features near the 8 {\\mu}m. These SF galaxies\nshowing PAHs in the mid-IR include various types from quiescent to starbursts.\nSome of our sample show shortage of 8 {\\mu}m luminosity compared to the total\nIR luminosity and this PAH deficit gets severe in more luminous IR galaxies,\nsuggesting PAH molecules in these galaxies destroyed by strong radiation field\nfrom SF region or a large amount of cold dust in ISM. The specific SFR of our\nsample shows mass dependent time evolution which is consistent with downsizing\nevolutionary pattern.", "positive": "A Survey of Atomic Carbon [C I] in High-redshift Main-Sequence Galaxies: We present the first results of an ALMA survey of the lower fine structure\nline of atomic carbon [C I]$(^3P_1\\,-\\,^{3}P_0)$ in far infrared-selected\ngalaxies on the main sequence at $z\\sim1.2$ in the COSMOS field. We compare our\nsample with a comprehensive compilation of data available in the literature for\nlocal and high-redshift starbursting systems and quasars. We show that the [C\nI]($^3P_1$$\\rightarrow$$^3P_0$) luminosity correlates on global scales with the\ninfrared luminosity $L_{\\rm IR}$ similarly to low-$J$ CO transitions. We report\na systematic variation of $L'_{\\rm [C\\,I]^3P_1\\,-\\, ^3P_0}$/$L_{\\rm IR}$ as a\nfunction of the galaxy type, with the ratio being larger for main-sequence\ngalaxies than for starbursts and sub-millimeter galaxies at fixed $L_{\\rm IR}$.\nThe $L'_{\\rm [C\\,I]^3P_1\\,-\\, ^3P_0}$/$L'_{\\rm CO(2-1)}$ and $M_{\\rm{[C\nI]}}$/$M_{\\rm dust}$ mass ratios are similar for main-sequence galaxies and for\nlocal and high-redshift starbursts within a 0.2 dex intrinsic scatter,\nsuggesting that [C I] is a good tracer of molecular gas mass as CO and dust. We\nderive a fraction of $f_{\\rm{[C\\,I]}} = M_{\\rm{[C\\,I]}} / M_{\\rm{C}}\\sim3-13$%\nof the total carbon mass in the atomic neutral phase. Moreover, we estimate the\nneutral atomic carbon abundance, the fundamental ingredient to calibrate [C I]\nas a gas tracer, by comparing $L'_{\\rm [C\\,I]^3P_1\\,-\\, ^3P_0}$ and available\ngas masses from CO lines and dust emission. We find lower [C I] abundances in\nmain-sequence galaxies than in starbursting systems and sub-millimeter\ngalaxies, as a consequence of the canonical $\\alpha_{\\rm CO}$ and gas-to-dust\nconversion factors. This argues against the application to different galaxy\npopulations of a universal standard [C I] abundance derived from highly biased\nsamples." }, { "anchor": "A structure function analysis of VST-COSMOS AGN: We present our sixth work in a series dedicated to variability studies of\nactive galactic nuclei (AGN) based on the survey of the COSMOS field by the VLT\nSurvey Telescope (VST). Its 54 r-band visits over 3.3 yr and single-visit depth\nof 24.6 r-band mag make this dataset a valuable scaled-down version that can\nhelp forecast the performance of the Rubin Observatory Legacy Survey of Space\nand Time (LSST). This work is centered on the analysis of the structure\nfunction (SF) of VST-COSMOS AGN, investigating possible differences in its\nshape and slope related to how the AGN were selected, and explores possible\nconnections between the ensemble variability of AGN and black-hole mass,\naccretion rate, bolometric luminosity, redshift, and obscuration of the source.\nGiven its features, our dataset opens up the exploration of samples ~2 mag\nfainter than most of the literature to date. We identify several samples of AGN\n- 677 in total - obtained by a variety of selection techniques which partly\noverlap. Our analysis compares results for the various samples. We split each\nsample in two based on the median of the physical property of interest, and\nanalyze differences in the shape and slope of the SF, and possible causes.\nWhile the shape of the SF does not change with depth, it is highly affected by\nthe type of AGN (unobscured/obscured) included in the sample. Where a linear\nregion can be identified, we find that the variability amplitude anticorrelates\nwith accretion rate and bolometric luminosity, consistent with previous\nliterature on the topic, while no dependence on black-hole mass emerges from\nthis study. With its longer baseline and denser and more regular sampling, the\nLSST will allow an improved characterization of the SF and its dependencies on\nthe mentioned physical properties over much larger AGN samples.", "positive": "Evolution of Galaxy Types and HI Gas Contents in Galaxy Groups: Using the group crossing time $t_{\\rm c}$ as an age indicator for galaxy\ngroups, we have investigated the correlation between $t_{\\rm c}$ and the group\nspiral fraction, as well as between $t_{\\rm c}$ and the neutral hydrogen gas\nfraction of galaxy groups. Our galaxy group sample is selected from the SDSS\nDR7 catalog, and the group spiral fraction is derived from the Galaxy Zoo\nmorphological data set. We found that the group spiral galaxy fraction is\ncorrelated with the group crossing time. We further cross matched the latest\nreleased ALFALFA 70\\% HI source catalog with the SDSS group catalog and have\nidentified 172 groups from the SDSS survey whose total HI mass can be derived\nby summing up the HI mass of all the HI sources within the group radius. For\nthe galaxies not detected in the ALFALFA, we estimate their HI masses based on\nthe galaxies' optical colors and magnitudes. Our sample groups contain more\nthan 8 member galaxies, they cover a wide range of halo masses and are\ndistributed in different cosmic environments. We derived the group HI mass\nfraction which is the ratio of group HI mass to the group virial mass. We found\na correlation between the HI mass fraction and the group crossing time. Our\nresults suggest that long time scale mechanisms such as starvation seem to play\na more important role than short time scale processes like stripping in\ndepleting HI gas in the SDSS galaxy groups." }, { "anchor": "Atomic hydrogen in star-forming galaxies at intermediate redshifts: We have used the upgraded Giant Metrewave Radio Telescope to carry out a deep\n(117 on-source hours) L-band observation of the Extended Groth Strip, to\nmeasure the average neutral hydrogen (HI) mass and median star formation rate\n(SFR) of star-forming galaxies, as well as the cosmic HI mass density, at $0.2\n< z < 0.4$. This was done by stacking the HI 21cm emission and the rest-frame\n1.4 GHz radio continuum from 445 blue star-forming galaxies with $\\rm M_B \\leq\n-17$ at $z_{\\rm mean} \\approx 0.34$. The stacked HI 21cm emission signal is\ndetected at $\\approx 7\\sigma$ significance, implying an average HI mass of $\\rm\n\\langle M_{HI} \\rangle = (4.93 \\pm 0.70) \\times 10^9 \\: M_{\\odot}$. We also\nstacked the rest-frame 1.4 GHz radio continuum emission of the same galaxies,\nto obtain a median SFR of $(0.54 \\pm 0.06) \\: {\\rm M}_\\odot$ yr$^{-1}$; this\nimplies an average atomic gas depletion time scale of $\\rm \\langle \\Delta\nt_{HI}\\rangle \\approx$ 9 Gyr, consistent with values in star-forming galaxies\nin the local Universe. This indicates that the star-formation efficiency does\nnot change significantly over the redshift range $0 - 0.4$. We used the\ndetection of the stacked HI 21cm emission signal to infer the normalized cosmic\nHI mass density $(\\rm \\rho_{HI}/\\rho_{c,0})$ in star-forming galaxies at $z\n\\approx 0.34$. Assuming the local relation between HI mass and absolute\nB-magnitude, we obtain $\\rm \\rho_{HI}/\\rho_{c,0} = (4.81 \\pm 0.75) \\times\n10^{-4}$, implying no significant evolution in $\\rm \\rho_{HI}/\\rho_{c,0}$ from\n$z \\approx 0.4$ to the present epoch.", "positive": "Short-lived radioisotopes in meteorites from Galactic-scale correlated\n star formation: Meteoritic evidence shows that the Solar system at birth contained\nsignificant quantities of short-lived radioisotopes (SLRs) such as 60Fe and\n26Al (with half-lives of 2.6 and 0.7 Myr respectively) produced in supernova\nexplosions and in the Wolf-Rayet winds that precede them. Proposed explanations\nfor the high SLR abundance include formation of the Sun in a\nsupernova-triggered collapse or in a giant molecular cloud (GMC) that was\nmassive enough to survive multiple supernovae (SNe) and confine their ejecta.\nHowever, the former scenario is possible only if the Sun is a rare outlier\namong massive stars, while the latter appears to be inconsistent with the\nobservation that 26Al is distributed with a scale height significantly larger\nthan GMCs. In this paper, we present a high-resolution chemo-hydrodynamical\nsimulation of the entire Milky-Way Galaxy, including stochastic star formation,\nHII regions, SNe, and element injection, that allows us to measure for the\ndistribution of 60Fe/56Fe and 26Al/27Al ratios over all stars in the Galaxy. We\nshow that the Solar System's abundance ratios are well within the normal range,\nbut that SLRs originate neither from triggering nor from confinement in\nlong-lived clouds as previously conjectured. Instead, we find that SLRs are\nabundant in newborn stars because star formation is correlated on galactic\nscales, so that ejecta preferentially enrich atomic gas that will subsequently\nbe accreted onto existing GMCs or will form new ones. Thus new generations of\nstars preferentially form in patches of the Galaxy contaminated by previous\ngenerations of stellar winds and supernovae." }, { "anchor": "Entropy-Conserving Scheme for Modeling Nonthermal Energies in Fluid\n Dynamics Simulations: We compare the performance of energy-based and entropy-conserving schemes for\nmodeling nonthermal energy components, such as unresolved turbulence and cosmic\nrays, using idealized fluid dynamics tests and isolated galaxy simulations.\nWhile both methods are aimed to model advection and adiabatic compression or\nexpansion of different energy components, the energy-based scheme numerically\nsolves the nonconservative equation for the energy density evolution, while the\nentropy-conserving scheme uses a conservative equation for modified entropy.\nUsing the standard shock tube and Zel'dovich pancake tests, we show that the\nenergy-based scheme results in a spurious generation of nonthermal energy on\nshocks, while the entropy-conserving method evolves the energy adiabatically to\nmachine precision. We also show that, in simulations of an isolated $L_\\star$\ngalaxy, switching between the schemes results in $\\approx 20-30\\%$ changes of\nthe total star formation rate and a significant difference in morphology,\nparticularly near the galaxy center. We also outline and test a simple method\nthat can be used in conjunction with the entropy-conserving scheme to model the\ninjection of nonthermal energies on shocks. Finally, we discuss how the\nentropy-conserving scheme can be used to capture the kinetic energy dissipated\nby numerical viscosity into the subgrid turbulent energy implicitly, without\nexplicit source terms that require calibration and can be rather uncertain. Our\nresults indicate that the entropy-conserving scheme is the preferred choice for\nmodeling nonthermal energy components, a conclusion that is equally relevant\nfor Eulerian and moving-mesh fluid dynamics codes.", "positive": "The structure and characteristic scales of molecular clouds: The structure of molecular clouds (MCs) holds important clues on the physical\nprocesses that lead to their formation and subsequent evolution. While it is\nwell established that turbulence imprints a self-similar structure to the\nclouds, other processes, such as gravity and stellar feedback, can break their\nscale-free nature. The break of self-similarity can manifest itself in the\nexistence of characteristic scales that stand out from the underlying structure\ngenerated by turbulent motions. We investigate the structure of the Cygnus-X\nNorth and the Polaris MCs which represent two extremes in terms of their star\nformation activity. We characterize the structure of the clouds using the\ndelta-variance ($\\Delta$-variance) spectrum. In Polaris, the structure of the\ncloud is self-similar over more than one order of magnitude in spatial scales.\nIn contrast, the $\\Delta$-variance spectrum of Cygnus-X exhibits an excess and\na plateau on physical scales of ~0.5-1.2 pc. In order to explain the\nobservations for Cygnus-X, we use synthetic maps in which we overlay\npopulations of discrete structures on top of a fractal Brownian motion (fBm)\nimage. The properties of these structures such as their major axis sizes,\naspect ratios, and column density contrasts are randomly drawn from\nparameterized distribution functions. We show that it is possible to reproduce\na $\\Delta$-variance spectrum that resembles the one of the Cygnus-X cloud. We\nalso use a \"reverse engineering\" approach in which we extract the compact\nstructures in the Cygnus-X cloud and re-inject them on an fBm map. The\ncalculated $\\Delta$-variance using this approach deviates from the observations\nand is an indication that the range of characteristic scales observed in\nCygnus-X is not only due to the existence of compact sources, but is a\nsignature of the whole population of structures, including more extended and\nelongated structures" }, { "anchor": "Searching for further evidence for cloud-cloud collisions in L1188: In order to search for further observational evidence of cloud-cloud\ncollisions in one of the promising candidates, L1188, we carried out\nobservations of multiple molecular lines toward the intersection region of the\ntwo nearly orthogonal filamentary molecular clouds in L1188. Based on these\nobservations, we find two parallel filamentary structures, both of which have\nat least two velocity components being connected with broad bridging features.\nWe also found a spatially complementary distribution between the two molecular\nclouds, as well as enhanced $^{13}$CO emission and $^{12}$CO self-absorption\ntoward their abutting regions. At the most blueshifted velocities, we unveil a\n1~pc-long arc ubiquitously showing $^{12}$CO line wings. We discover two 22 GHz\nwater masers, which are the first maser detections in L1188. An analysis of\nline ratios at a linear resolution of 0.2 pc suggests that L1188 is\ncharacterised by kinetic temperatures of 13--23~K and H$_{2}$ number densities\nof 10$^{3}$--10$^{3.6}$ cm$^{-3}$. On the basis of previous theoretical\npredictions and simulations, we suggest that these observational features can\nbe naturally explained by the scenario of a cloud-cloud collision in L1188,\nalthough an additional contribution of stellar feedback from low-mass young\nstellar objects cannot be ruled out.", "positive": "The Evolution of Star Formation Activity in Cluster Galaxies Over\n $0.1510^{10.1}\\,M_{\\odot}$) cluster galaxies using a sample of\n25 clusters over $0.15 3 . 10^40 ergs s^-1)\nlocal galaxies, and this offset cannot be explained by simple systematic\noffsets in the derived quantities. At stellar masses above ~10^9 Msol and star\nformation rates above ~10 Msol yr^-1, the z ~ 2.1 galaxies have higher oxygen\nabundances than their local counterparts, while the opposite is true for\nlower-mass, lower-SFR systems.", "positive": "Study of Integrated Spectra of Four Globular Clusters in M31: The results of determining the metallicity, age, helium mass fraction (Y) and\nabundances of the elements C, N, Mg, Ca, Mn, Ti and Cr by moderate resolution\nspectra for four globular clusters in the galaxy M 31: Bol 6, Bol 20, Bol 45\nand Bol 50 are presented. The chemical composition for Bol 20 and Bol 50, and Y\nfor four clusters are determined for the first time. The spectra of the studied\nobjects were obtained with the 6-meter telescope of the SAO RAS in 2020. All\nthe clusters under study turned out to be older than 11 Gyrs. The determined\nmetallicities [Fe/H] are in the range from -1.1 to -0.75 dex. They are lower\nthan the metallicity of stars of the M 31 halo at a given distance from the\ngalactic center (R_M31 < 10 kpc). The abundances of the elements of the\nalpha-process [alpha/Fe] = ([O/Fe] + [Mg/Fe] + [Ca/Fe])/3 of the four clusters\ncorrespond to those of the stars of the inner halo of M31." }, { "anchor": "The optical emission nebulae in the vicinity of WR 48 (Theta Mus); True\n Wolf-Rayet ejecta or unconnected supernova remnant?: During searches for new optical Galactic supernova remnants (SNRs) in the\nhigh resolution, high sensitivity Anglo-Australian Observatory/United Kingdom\nSchmidt Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane, we\nuncovered a variety of filamentary and more diffuse, extensive nebular\nstructures in the vicinity of Wolf-Rayet (WR) star 48 (Theta Muscae), only some\nof which were previously recognised. We used the double-beam spectrograph of\nthe Mount Stromlo and Siding Spring Observatory (MSSSO) 2.3-m to obtain low and\nmid resolution spectra of selected new filaments and structures in this region.\nDespite spectral similarities between the optical spectra of WR star shells and\nSNRs, a careful assessment of the new spectral and morphological evidence from\nour deep HAlpha imagery suggests that the putative shell of Theta Mus is not a\nWR shell at all, as has been commonly accepted, but is rather part of a more\ncomplex area of large-scale overlapping nebulosities in the general field of\nthe WR star. The emission comprises a possible new optical supernova remnant\nand a likely series of complex H II regions. Finally, we present the intriguing\ndetection of apparent collimated, directly opposing, ionized outflows close to\nTheta Mus itself which appears unique among such stars. Although possible\nartifacts or a temporary phenomenon monitoring of the star is recommended.", "positive": "2D chemical evolution model: the impact of galactic disc asymmetries on\n azimuthal chemical abundance variations: Galactic disc chemical evolution models generally ignore azimuthal surface\ndensity variation that can introduce chemical abundance azimuthal gradients.\nRecent observations, however, have revealed chemical abundance changes with\nazimuth in the gas and stellar components of both the Milky Way and external\ngalaxies. To quantify the effects of spiral arm density fluctuations on the\nazimuthal variations of the oxygen and iron abundances in disc galaxies. We\ndevelop a new 2D galactic disc chemical evolution model, capable of following\nnot just radial but also azimuthal inhomogeneities. The density fluctuations\nresulting from a Milky Way-like N-body disc formation simulation produce\nazimuthal variations in the oxygen abundance gradients of the order of 0.1 dex.\nMoreover, in agreement with the most recent observations in external galaxies,\nthe azimuthal variations are more evident in the outer galactic regions. Using\na simple analytical model, we show that the largest fluctuations with azimuth\nresult near the spiral structure corotation resonance, where the relative speed\nbetween spiral and gaseous disc is the slowest. In conclusion we provided a new\n2D chemical evolution model capable of following azimuthal density variations.\nDensity fluctuations extracted from a Milky Way-like dynamical model lead to a\nscatter in the azimuthal variations of the oxygen abundance gradient in\nagreement with observations in external galaxies. We interpret the presence of\nazimuthal scatter at all radii by the presence of multiple spiral modes moving\nat different pattern speeds, as found in both observations and numerical\nsimulations." }, { "anchor": "First Interstellar HCO$^+$ Maser: A previously unseen maser in the J = 1 - 0 transition of HCO$^+$ has been\ndetected by the Combined Array for Millimeter-wave Astronomy (CARMA). A\nsub-arcsecond map was produced of the 2 arcmin$^2$ region around DR21(OH),\nwhich has had previous detections of OH and methanol masers. This new object\nhas remained undetected until now due to its extremely compact size. The object\nhas a brightness temperature of $>$ 2500 K and a FWHM linewidth of 0.497 km\ns$^{-1}$, both of which suggest non-thermal line emission consistent with an\nunsaturated maser. This object coincides in position and velocity with the\nmethanol maser named DR21(OH)-1 by \\citet{plambeck90}. No compact HCO$^+$\nemission was present in the CARMA data towards the other methanol masers\ndescribed in that paper. These new results support the theory introduced in\n\\citet{plambeck90} that these masers likely arise from strong outflows\ninteracting with low mass, high density pockets of molecular gas. This is\nfurther supported by recent observations of a CO outflow by \\citet{zapata12}\nthat traces the outflow edges and confirms that the maser position lies along\nthe edge of the outflow where interaction with molecular tracers can occur.", "positive": "The Large Magellanic Cloud stellar content with SMASH: I. Assessing the\n stability of the Magellanic spiral arms: The Large Magellanic Cloud (LMC) is the closest and most studied example of\nan irregular galaxy. Among its principal defining morphological features, its\noff-centred bar and single spiral arm stand out, defining a whole family of\ngalaxies known as the Magellanic spirals (Sm). These structures are thought to\nbe triggered by tidal interactions and possibly maintained via gas accretion.\nHowever, it is still unknown whether they are long-lived stable structures. In\nthis work, by combining photometry that reaches down to the oldest main\nsequence turn-off in the colour-magnitude diagrams (CMD, up to a distance of\n$\\sim$4.4 kpc from the LMC centre) from the SMASH survey and CMD fitting\ntechniques, we find compelling evidence supporting the long-term stability of\nthe LMC spiral arm, dating the origin of this structure to more than 2~Gyr ago.\nThe evidence suggests that the close encounter between the LMC and the Small\nMagellanic Cloud (SMC) that produced the gaseous Magellanic Stream and its\nLeading Arm (LA) also triggered the formation of the LMC's spiral arm. Given\nthe mass difference between the Clouds and the notable consequences of this\ninteraction, we can speculate that this should have been one of their closest\nencounters. These results set important constraints on the timing of LMC-SMC\ncollisions, as well as on the physics behind star formation induced by tidal\nencounters." }, { "anchor": "Detection of Lyman Continuum from 3.0 < z < 3.5 Galaxies in the HETDEX\n Survey: Questions as to what drove the bulk reionization of the Universe, how that\nreionization proceeded, and how the hard ionizing radiation reached the\nintergalactic medium remain open and debated. Observations probing that epoch\nare severely hampered by the increasing amounts of neutral gas with increasing\nredshift, so a small, but growing number of experiments are targeting star\nforming galaxies ($z\\sim3$) as proxies. However, these studies, while providing\nfantastic detail, are time intensive, contain relatively few targets, and can\nsuffer from selection biases. As a complementary alternative, we investigate\nwhether stacking the already vast (and growing) numbers of low-resolution\n($\\Delta \\lambda / \\lambda = 800$) Lyman-$\\alpha$ Emitting (LAE) galaxy spectra\nfrom the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) can be used to\nmeasure ionizing photons (restframe 880-910\\AA) escaping their galaxy hosts. As\na blind survey, HETDEX avoids the biases from continuum selected galaxies and\nits planned 540 square degree coverage promotes the statistical power of large\nnumbers. In this paper, we confirm the feasibility of Lyman continuum detection\nby carefully selecting a sample of \\lyccount\\ high redshift ($z\\sim$3) LAEs\nfrom a subset of HETDEX observations, stacking their spectra and measuring a\n$\\gtrsim$3$\\sigma$ detection of $0.10 \\mu$Jy restframe Lyman continuum\nemission, uncorrected for attenuation in the intergalactic medium, over the\nfull sample stack ($3.0 < z < 3.5$ and $-22.0 \\lesssim M_{\\text{UV}} \\lesssim\n-19.0$).", "positive": "A hot bubble at the centre of M81: Context. Messier 81 has the nearest active nucleus with broad H$\\alpha$\nemission. A detailed study of this galaxy's centre is important for\nunderstanding the innermost structure of the AGN phenomenon.\n Aims. Our goal is to seek previously undetected structures using additional\ntechniques to reanalyse a data cube obtained with the GMOS-IFU installed on the\nGemini North telescope (Schnorr M\\\"uller et al. 2011).\n Method. We analysed the data cube using techniques of noise reduction,\nspatial deconvolution, starlight subtraction, PCA tomography, and comparison\nwith HST images.\n Results. We identified a hot bubble with T $>$ 43500 K that is associated\nwith strong emission of [N II]$\\lambda$5755\\AA\\ and a high [O\nI]$\\lambda$6300/H$\\alpha$ ratio; the bubble displays a bluish continuum,\nsurrounded by a thin shell of H$\\alpha$ + [N II] emission. We also reinterpret\nthe outflow found by Schnorr M\\\"uller et al. (2011) showing that the\nblueshifted cone nearly coincides with the radio jet, as expected.\n Conclusions. We interpret the hot bubble as having been caused by post\nstarburst events that left one or more clusters of young stars, similar to the\nones found at the centre of the Milky Way, such as the Arches and the IRS 16\nclusters. Shocked structures from combined young stellar winds or supernova\nremnants are probably the cause of this hot gas and the low ionization\nemission." }, { "anchor": "Collisional excitation of far-infrared line emissions from warm\n interstellar carbon monoxide (CO): Motivated by recent observations with Herschel/PACS, and the availability of\nnew rate coefficients for the collisional excitation of CO (Yang et al. 2010),\nthe excitation of warm astrophysical CO is revisited with the use of numerical\nand analytic methods. For the case of an isothermal medium, results have been\nobtained for a wide range of gas temperatures (100 to 5000 K) and H2 densities\n(1E+3 to 1E+9 cm-3), and presented in the form of rotational diagrams, in which\nthe logarithm of the column density per magnetic substate, log (N[J]/g[J]), is\nplotted for each state, as a function of its energy, E[J]. For rotational\ntransitions in the wavelength range accessible to Herschel/PACS, such diagrams\nare nearly linear when n(H2) > 1E+8 cm-3. When log10(n[H2]) = 6.8 to 8, they\nexhibit significant negative curvature, whereas when log10(n[H2]) < 4.8 the\ncurvature is uniformly positive throughout the PACS-accessible range. Thus, the\nobservation of a positively-curved CO rotational diagram does not NECESSARILY\nrequire the presence of multiple temperature components. Indeed, for some\nsources observed with Herschel/PACS, the CO rotational diagrams show a modest\npositive curvature that can be explained by a single isothermal component.\nTypically, the required physical parameters are H2 densities in the 1E+4 to\n1E+5 cm-3 range and temperatures, T, close to the maximum at which CO can\nsurvive. Other sources exhibit rotational diagrams with more curvature than can\nbe accounted for by a single temperature component. For the case of a medium\nwith a power-law distribution of gas temperatures, with dN/dT proportional to T\nto the power -b, results have been obtained for H2 densities 1E+3 to 1E+9 cm-3\nand power-law indices, b, in the range 1 to 5; such a medium can account for a\nCO rotational diagram that is more positively curved than any resulting from an\nisothermal medium.", "positive": "H2S in the L1157-B1 Bow shock: Sulfur-bearing molecules are highly reactive in the gas phase of the ISM.\nHowever, the form in which most of the sulfur is locked onto interstellar dust\ngrains is unknown. By taking advantage of the short time-scales of shocks in\nyoung molecular outflows, one could track back the main form of sulfur in the\nices. In this paper, six transitions of H$_2$S and its isotopologues in the\nL1157-B1 bowshock have been detected using data from the Herschel-CHESS survey\nand the IRAM-30m ASAI large program. These detections are used to calculate the\nproperties of H$_2$S gas in L1157-B1 through use of a rotation diagram and to\nexplore the possible carriers of sulfur on the grains. The isotopologue\ndetections allow the first calculation of the H$_2$S deuteration fraction in an\noutflow from a low mass protostar. The fractional abundance of H$_2$S in the\nregion is found to be 6.0$\\times$10$^{-7}$ and the deuteration fraction is\n2$\\times$10$^{-2}$. In order to investigate the form of sulfur on the grains, a\nchemical model is run with four different networks, each with different\nbranching ratios for the freeze out of sulfur bearing species into molecules\nsuch as OCS and H$_2$S. It is found that the model best fits the data when at\nleast half of each sulfur bearing species hydrogenates when freezing. We\ntherefore conclude that a significant fraction of sulfur in L1157-B1 is likely\nto be locked in H$_2$S on the grains." }, { "anchor": "The relationship between Mg II broad emission and quasar inclination\n angle: Several observed spectral properties of quasars are believed to be influenced\nby quasar orientation. In this investigation we examine the effect of\norientation on the Mg II line located at 2798 {\\AA} in a sample of 36\nradio-loud quasars, with orientation angles having been obtained in a previous\nstudy using radio observations. We find no significant relationship between\norientation angle and either Mg II line full-width at half-maximum or\nequivalent width. The lack of correlation with inclination angle contradicts\nprevious studies which also use radio data as a proxy for inclination angle and\nsuggests the Mg II emission region does not occupy a disk-like geometry. The\nlack of correlation with Mg II equivalent width, however, is reported in at\nleast one previous study. Although the significance is not very strong (86\npercent), there is a possible negative relationship between inclination angle\nand Fe II strength which, if true, could explain the Fe II anti-correlation\nwith [O III ] strength associated with Eigenvector 1. Interestingly, there are\nobjects having almost edge-on inclinations while still exhibiting broad lines.\nThis could be explained by a torus which is either clumpy (allowing sight lines\nto the central engine) or mis-aligned with the accretion disk.", "positive": "Residual Energy in Magnetohydrodynamic Turbulence: There is mounting evidence in solar wind observations and in numerical\nsimulations that kinetic and magnetic energies are not in equipartition in\nmagnetohydrodynamic turbulence. The origin of their mismatch, the residual\nenergy E_r=E_v-E_b, is not well understood. In the present work this effect is\nstudied analytically in the regime of weak magnetohydrodynamic turbulence. We\nfind that residual energy is spontaneously generated by turbulent dynamics, and\nit has a negative sign, in good agreement with the observations. We obtain that\nthe residual energy condenses around k_||=0 with its k_||-spectrum broadening\nlinearly with k_perp, where k_|| and k_perp are the wavenumbers parallel and\nperpendicular to the background magnetic field, and the field-perpendicular\nspectrum of the residual energy has the scaling E_r(k_perp)\\propto k_perp^{-1}\nin the inertial interval. These results are found to be in agreement with\nnumerical simulations. We propose that residual energy plays a fundamental role\nin Alfvenic turbulence and it should be taken into account for correct\ninterpretation of observational and numerical data." }, { "anchor": "Gravitational and mass distribution effects on stationary superwinds: Here, we model the effect of non-uniform dynamical mass distributions and\ntheir associated gravitational fields on the stationary galactic superwind\nsolution. We do this by considering an analogue injection of mass and energy\nfrom stellar winds and SNe. We consider both compact dark-matter and baryonic\nhaloes that does not extend further from the galaxies optical radii $R_{\\rm\nopt}$ as well as extended gravitationally-interacting ones. We consider halo\nprofiles that emulate the results of recent cosmological simulations and\ncoincide also with observational estimations from galaxy surveys. This allows\nto compare the analytical superwind solution with outflows from different kinds\nof galaxies. We give analytical formulae that establish when an outflow is\npossible and also characterize distinct flow regimes and enrichment scenarios.\nWe also constraint the parameter space by giving approximate limits above which\ngravitation, self-gravitation and radiative cooling can inhibit the stationary\nflow. We obtain analytical expressions for the free superwind hydrodynamical\nprofiles. We find that the existence or inhibition of the superwind solution\nhighly depends on the steepness and concentration of the dynamical mass and the\nmass and energy injection rates. We compare our results with observational data\nand a recent numerical work. We put our results in the context of the\nmass-metallicity relationship to discuss observational evidence related to the\nselective loss of metals from the least massive galaxies and also discuss the\ncase of massive galaxies.", "positive": "Implications of a density dependent IMF for the statistics of\n progenitors of gravitational wave sources: Observations of mergers of multi-compact object systems offer insights to the\nformation processes of massive stars in globular clusters. Simulations of\nstellar clusters, may be used to understand and interpret observations.\nSimulations generally adopt an Initial Mass Function (IMF) with a Salpeter\nslope at the high mass end, for the initial distribution of stellar masses.\nHowever, observations of the nearest high mass star forming regions point to\nthe IMF at the high mass end being flatter than Salpeter, in regions where the\nstellar densities are high. We explore the impact of this on the formation rate\nof potential GW sources, estimated from standard considerations. Globular\nclusters being significant contributors to the ionization history of the\nuniverse, the results have implications for the same. It impacts our ability to\nexplore the putative mass gap, between the upper limit for neutron star masses\nand the lower limit for black hole masses, also." }, { "anchor": "Connection among environment, cloud-cloud collision speed, and star\n formation activity in the strongly barred galaxy NGC1300: Cloud-cloud collision (CCC) has been suggested as a mechanism to induce\nmassive star formation. Recent simulations suggest that a CCC speed is\ndifferent among galactic-scale environments, which is responsible for observed\ndifferences in star formation activity. In particular, a high-speed CCC is\nproposed as a cause of star formation suppression in the bar regions in barred\nspiral galaxies. Focusing on the strongly barred galaxy NGC1300, we investigate\nthe CCC speed. We find the CCC speed in the bar and bar-end tend to be higher\nthan that in the arm. The estimated CCC speed is $\\sim20~\\rm km~s^{-1}$,\n$\\sim16~\\rm km~s^{-1}$, and $\\sim11~\\rm km~s^{-1}$ in the bar, bar-end, and\narm, respectively. Although the star formation activity is different in the bar\nand bar-end, the CCC speed and the number density of high-speed CCC with $>\n20~\\rm km~s^{-1}$ are high in both regions, implying the existence of other\nparameters that control the star formation. The difference in molecular gas\nmass (average density) of the giant molecular clouds (GMCs) between the bar\n(lower mass and lower density) and bar-end (higher mass and higher density) may\nbe cause for the different star formation activity. Combining with our previous\nstudy (Maeda et al.), the leading candidates of causes for the star formation\nsuppression in the bar in NGC1300 are the presence of a large amount of diffuse\nmolecular gases and high-speed CCCs between low mass GMCs.", "positive": "Supercritical growth pathway to overmassive black holes at cosmic dawn:\n coevolution with massive quasar hosts: Observations of the most luminous quasars at high redshifts ($z > 6$) have\nrevealed that the largest supermassive black holes (SMBHs) at those epochs tend\nto be substantially overmassive relative to their host galaxies compared to the\nlocal relations, suggesting they experienced rapid early growth phases. We\npropose an assembly model for the SMBHs that end up in rare massive\n$\\sim10^{12}~M_{\\odot}$ host halos at $z \\sim 6-7$, applying a kinetic feedback\nprescription for BHs accreting above the Eddington rate, provided by radiation\nhydrodynamic simulations for the long-term evolution of the accretion-flow\nstructure. The large inflow rates into these halos during their assembly enable\nthe formation of $>10^9~M_{\\odot}$ SMBHs by $z \\sim 6$, even starting from\nstellar-mass seeds at $z \\sim 30$, and even in the presence of outflows that\nreduce the BH feeding rate, especially at early times. This mechanism also\nnaturally yields a high BH-to-galaxy mass ratio of $> 0.01$ before the SMBH\nmass reaches $M_{\\rm BH} > 10^9~M_{\\odot}$ by $z \\sim 6$. These fast-growing\nSMBH progenitors are bright enough to be detected by upcoming observations with\nthe James Webb Space Telescope over a wide range of redshift ($7 < z < 15$),\nregardless of how they were seeded." }, { "anchor": "The HI Structure of the Local Volume Dwarf Galaxy Pisces A: Dedicated HI surveys have recently led to a growing category of low-mass\ngalaxies found in the Local Volume. We present synthesis imaging of one such\ngalaxy, Pisces A, a low-mass dwarf originally confirmed via optical imaging and\nspectroscopy of neutral hydrogen (HI) sources in the Galactic Arecibo L-band\nFeed Array HI (GALFA-HI) survey. Using HI observations taken with the Karl G.\nJansky Very Large Array (JVLA), we characterize the kinematic structure of the\ngas and connect it to the galaxy's environment and evolutionary history. While\nthe galaxy shows overall ordered rotation, a number of kinematic features\nindicate a disturbed gas morphology. These features are suggestive of a\ntumultuous recent history, and represent $\\sim 3.5$% of the total baryonic\nmass. We find a total baryon fraction $f_{\\rm bary} = 0.13$ if we include these\nfeatures. We also quantify the cosmic environment of Pisces A, finding an\napparent alignment of the disturbed gas with nearby, large scale filamentary\nstructure at the edge of the Local Void. We consider several scenarios for the\norigin of the disturbed gas, including gas stripping via ram pressure or\ngalaxy-galaxy interactions, as well as accretion and ram pressure compression.\nThough we cannot rule out a past interaction with a companion, our observations\nbest support the suggestion that the neutral gas morphology and recent star\nformation in Pisces A is a direct result of its interactions with the IGM.", "positive": "A Stellar Wind Origin for the G2 Cloud: Three-Dimensional Numerical\n Simulations: We present 3D, adaptive mesh refinement simulations of G2, a cloud of gas\nmoving in a highly eccentric orbit towards the galactic center. We assume that\nG2 originates from a stellar wind interacting with the environment of the Sgr\nA* black hole. The stellar wind forms a cometary bubble which becomes\nincreasingly elongated as the star approaches periastron. A few months after\nperiastron passage, streams of material begin to accrete on the central black\nhole with accretion rates $\\dot{M} \\sim 10^{-8}$ M$_\\odot$ yr$^{-1}$. Predicted\nBr$\\gamma$ emission maps and position-velocity diagrams show an elongated\nemission resembling recent observations of G2. A large increase in luminosity\nis predicted by the emission coming from the shocked wind region during\nperiastron passage. The observations, showing a constant Br$\\gamma$ luminosity,\nremain puzzling, and are explained here assuming that the emission is dominated\nby the free-wind region. The observed Br$\\gamma$ luminosity ($\\sim 8 \\times\n10^{30}$ erg s$^{-1}$) is reproduced by a model with a $v_w=50$ km s$^{-1}$\nwind velocity and a $10^{-7}$ M$_\\odot$ yr$^{-1}$ mass loss rate if the\nemission comes from the shocked wind. A faster and less dense wind reproduces\nthe Br$\\gamma$ luminosity if the emission comes from the inner, free wind\nregion. The extended cometary wind bubble, largely destroyed by the tidal\ninteraction with the black hole, reforms a few years after periastron passage.\nAs a result, the Br$\\gamma$ emission is more compact after periastron passage." }, { "anchor": "Diversity of dwarf galaxy IR-submm emission patterns: CLUES from\n hydrodynamical simulations: The spectral energy distributions (SEDs) of low-mass low-metallicity (dwarf)\ngalaxies are a challenging piece of the puzzle of galaxy formation in the near\nUniverse. These SEDs show some particular features in the submillimeter to\nfar-infrared wavelength range compared to normal, larger, and metal-richer\ngalaxies that cannot be explained by the current models. These can be\nsummarized as: a broadening of the IR peak, which implies a warmer dust\ncomponent; an excess of emission in the submm ($\\sim$500 $\\mu$m), that causes a\nflattening of the submm/FIR slope; and a very low intensity of PAH emission\nfeatures. With the aim of explaining these emission patterns, the SEDs of a\nsample of 27 simulated dwarf galaxies were calculated using the GRASIL-3D\nradiation transfer code. This code has the particularity that it separately\ntreats the radiative transfer through dust grains within molecular clouds and\nwithin the cirrus, the dense and diffuse components of the gas phase,\nrespectively. The simulated galaxies have stellar masses ranging from\n10$^6$-10$^9$ M$_\\odot$, and were obtained from a single simulation run within\na Local Group environment with initial conditions from the CLUES project. We\nreport a study of the IRAS, Spitzer and Herschel bands luminosities, and of the\nSFRs, dust, and gas (HI and H$_2$) mass contents. We find a satisfactory\nagreement with observational data, with GRASIL-3D naturally reproducing the\nspecific spectral features mentioned above. We conclude that the GRASIL-3D\ntwo-component dust model gives a physical interpretation of the emission of\ndwarf galaxies: molecular clouds and cirrus represent the warm and cold dust\ncomponents, respectively, needed to reproduce observational data.", "positive": "Direct evidence of dust growth in L183 from MIR light scattering: Theoretical arguments suggest that dust grains should grow in the dense cold\nparts of molecular clouds. Evidence of larger grains has so far been gathered\nin near/mid infrared extinction and millimeter observations. Interpreting the\ndata is, however, aggravated by the complex interplay of density and dust\nproperties (as well as temperature for thermal emission). We present new\nSpitzer data of L183 in bands that are sensitive and insensitive to PAHs. The\nvisual extinction AV map derived in a former paper was fitted by a series of 3D\nGaussian distributions. For different dust models, we calculate the scattered\nMIR radiation images of structures that agree agree with the AV map and compare\nthem to the Spitzer data. The Spitzer data of L183 show emission in the 3.6 and\n4.5 micron bands, while the 5.8 micron band shows slight absorption. The\nemission layer of stochastically heated particles should coincide with the\nlayer of strongest scattering of optical interstellar radiation, which is seen\nas an outer surface on I band images different from the emission region seen in\nthe Spitzer images. Moreover, PAH emission is expected to strongly increase\nfrom 4.5 to 5.8 micron, which is not seen. Hence, we interpret this emission to\nbe MIR cloudshine. Scattered light modeling when assuming interstellar medium\ndust grains without growth does not reproduce flux measurable by Spitzer. In\ncontrast, models with grains growing with density yield images with a flux and\npattern comparable to the Spitzer images in the bands 3.6, 4.5, and 8.0 micron." }, { "anchor": "Learning mid-IR emission spectra of polycyclic aromatic hydrocarbon\n populations from observations: The JWST will deliver large data sets of high-quality spectral data over the\n0.6-28 $\\mu$m range. It will combine sensitivity, spectral and spatial\nresolution. Specific tools are required to provide efficient scientific\nanalysis of such large data sets. Our aim is to illustrate the potential of\nunsupervised learning methods to get insights into chemical variations in the\npopulations that carry the aromatic infrared bands (AIBs), more specifically\nPAH species and carbonaceous very small grains (VSGs). We present a method\nbased on linear fitting and blind signal separation (BSS) for extracting\nrepresentative spectra for a spectral data set. The method is fast and robust,\nwhich ensures its applicability to JWST spectral cubes. We tested this method\non a sample of ISO-SWS data, which resemble most closely the JWST spectra in\nterms of spectral resolution and coverage. Four representative spectra were\nextracted. Their main characteristics appear consistent with previous studies\nwith populations dominated by cationic PAHs, neutral PAHs, evaporating VSGs,\nand large ionized PAHs, known as the PAH$^x$ population. In addition, the 3\n$\\mu$m range, which is considered here for the first time in a BSS method,\nreveals the presence of aliphatics connected to neutral PAHs. Each\nrepresentative spectrum is found to carry second-order spectral signatures\n(e.g. small bands), which are connected with the underlying chemical diversity\nof populations. However, the precise attribution of theses signatures remains\nlimited by the combined small size and heterogeneity of the sample of\nastronomical spectra available in this study. The upcoming JWST data will allow\nus to overcome this limitation. The large data sets of hyperspectral images\nprovided by JWST analysed with the proposed method, which is fast and robust,\nwill open promising perspectives for our understanding of the chemical\nevolution of the AIB carriers.", "positive": "A Kiloparsec-Scale Nuclear Stellar Disk in the Milky Way as a Possible\n Explanation of the High Velocity Peaks in the Galactic Bulge: The Apache Point Observatory Galactic Evolution Experiment has measured the\nstellar velocities of red giant stars in the inner Milky Way. We confirm that\nthe line of sight velocity distributions (LOSVDs) in the mid-plane exhibit a\nsecond peak at high velocities, whereas those at |b| = 2degrees do not. We use\na high resolution simulation of a barred galaxy, which crucially includes gas\nand star formation, to guide our interpretation of the LOSVDs. We show that the\ndata are fully consistent with the presence of a thin, rapidly rotating,\nnuclear disk extending to ~1 kpc. This nuclear disk is orientated perpendicular\nto the bar and is likely to be composed of stars on x2 orbits. The gas in the\nsimulation is able to fall onto such orbits, leading to stars populating an\northogonal disk." }, { "anchor": "Tidal disruption rate suppression by the event horizon of spinning black\n holes: The rate of observable tidal disruption events (TDEs) by the most massive\nblack holes (BHs) is suppressed due to direct capture of stars by the event\nhorizon. This suppression effect depends on the shape of the horizon and holds\nthe promise of probing the spin distribution of dormant BHs at the centers of\ngalaxies. By extending the frozen-in approximation commonly used in the\nNewtonian limit, we propose a general relativistic criterion for the tidal\ndisruption of a star of given interior structure. The rate suppression factor\nis then calculated for different BH masses, spins, and realistic stellar\npopulations. We find that either a high BH spin (> 0.5) or a young stellar\npopulation (< 1 Gyr) allows TDEs to be observed from BHs significantly more\nmassive than 10^8 solar masses. We call this spin-age degeneracy (SAD). This\nlimits our utility of the TDE rate to constrain the BH spin distribution,\nunless additional constraints on the age of the stellar population or the mass\nof the disrupted star can be obtained by modeling the TDE radiation or the\nstellar spectral energy distribution near the galactic nuclei.", "positive": "Toward understanding physical origin of 2175\u00c5 extinction bump in\n interstellar medium: The 2175 {\\AA} ultraviolet (UV) extinction bump in interstellar medium (ISM)\nof the Milky Way was discovered in 1965. After intensive exploration of more\nthan a half century, however, its exact origin still remains a big conundrum\nthat is being debated. Here we propose a mixture model by which the extinction\nbump in ISM is argued possibly relevant to the clusters of hydrogenated\nT-carbon (HTC) molecules (C40H16) that have intrinsically a sharp absorption\npeak at the wavelength 2175 {\\AA}. By linearly combining the calculated\nabsorption spectra of HTC mixtures, graphite, MgSiO3 and Fe2SiO4, we show that\nthe UV extinction curves of optional six stars can be nicely fitted. This\npresent work poses an alternative explanation toward understanding the physical\norigin of the 2175 {\\AA} extinction bump in ISM of the Milky Way." }, { "anchor": "A hidden reservoir of Fe/FeS in interstellar silicates?: The depletion of iron and sulphur into dust in the interstellar medium and\nthe exact nature of interstellar amorphous silicate grains is still an open\nquestion. We study the incorporation of iron and sulphur into amorphous\nsilicates of olivine- and pyroxene-type and their effects on the dust\nspectroscopy and thermal emission. We used the Maxwell-Garnett effective-medium\ntheory to construct the optical constants for a mixture of silicates, metallic\niron, and iron sulphide. We also studied the effects of iron and iron sulphide\nin aggregate grains. Iron sulphide inclusions within amorphous silicates that\ncontain iron metal inclusions shows no strong differences in the optical\nproperties of the grains. A mix of amorphous olivine- and pyroxene-type\nsilicate broadens the silicate features. An amorphous carbon mantle with a\nthickness of 10 nm on the silicate grains leads to an increase in absorption on\nthe short-wavelength side of the 10 $\\mu$m silicate band. The assumption of\namorphous olivine-type and pyroxene-type silicates and a 10 nm thick amorphous\ncarbon mantle better matches the interstellar silicate band profiles. Including\niron nano-particles leads to an increase in the mid-IR extinction, while up to\n5 ppm of sulphur can be incorporated as Fe/FeS nano inclusions into silicate\ngrains without leaving a significant trace of its presence.", "positive": "Can warm absorbers be driven by ultra-fast outflows?: Warm absorbers (WAs) located approximately in the region of $1-1000$ parsecs\nare common phenomena in many active galactic nuclei (AGNs). The driving\nmechanism of WAs is still under debate. Ultra-fast outflows (UFOs) which are\nlaunched very close to the central black hole are also frequently observed in\nAGNs. When UFOs move outwards, they will collide with the interstellar medius\n(ISM) gas. In this paper, we study the possibility that whether WAs can be\ngenerated by the interaction between ISM gas and the UFOs. We find that under\nsome ISM gas conditions, WAs can be generated. However, the covering factor of\nWAs is much smaller than that given by observations. This indicates that other\nmechanisms should also be at work. We also find that the properties of the WAs\nmainly depend on the density of the ISM injected into the computational domain\nfrom the outer radial boundary (1000 parsec). The higher the density of the ISM\nis, the higher the mass flux and kinetic power of the WAs will be. The kinetic\npower of the UFO driven WAs is much less than $1\\%$ of the bolometric\nluminosity of its host AGNs. Therefore, the UFO driven WAs might not contribute\nsufficient feedback to its host galaxy." }, { "anchor": "Velocity-Coherent Substructure in TMC-1: Inflow and Fragmentation: Filamentary structures have been found nearly ubiquitously in molecular\nclouds and yet their formation and evolution is still poorly understood. We\nexamine a segment of Taurus Molecular Cloud 1 (TMC-1) that appears as a single,\nnarrow filament in continuum emission from dust. We use the Regularized\nOptimization for Hyper-Spectral Analysis (ROHSA), a Gaussian decomposition\nalgorithm which enforces spatial coherence when fitting multiple velocity\ncomponents simultaneously over a data cube. We analyze HC$_5$N (9-8) line\nemission as part of the Green Bank Ammonia Survey (GAS) and identify three\nvelocity-coherent components with ROHSA. The two brightest components extend\nthe length of the filament, while the third component is fainter and clumpier.\nThe brightest component has a prominent transverse velocity gradient of $2.7\n\\pm 0.1$ km s$^{-1}$ pc$^{-1}$ that we show to be indicative of gravitationally\ninduced inflow. In the second component, we identify regularly spaced emission\npeaks along its length. We show that the local minima between pairs of adjacent\nHC$_5$N peaks line up closely with submillimetre continuum emission peaks,\nwhich we argue is evidence for fragmentation along the spine of TMC-1. While\ncoherent velocity components have been described as separate physical\nstructures in other star-forming filaments, we argue that the two bright\ncomponents identified in HC$_5$N emission in TMC-1 are tracing two layers in\none filament: a lower density outer layer whose material is flowing under\ngravity towards the higher density inner layer of the filament.", "positive": "Herschel/SPIRE Sub-millimeter Spectra of Local Active Galaxies: We present the sub-millimeter spectra from 450 GHz to 1550 GHz of eleven\nnearby active galaxies observed with the SPIRE Fourier Transform Spectrometer\n(SPIRE/FTS) onboard Herschel. We detect CO transitions from J_up = 4 to 12, as\nwell as the two [CI] fine structure lines at 492 and 809 GHz and the [NII] 461\nGHz line. We used radiative transfer models to analyze the observed CO spectral\nline energy distributions (SLEDs). The FTS CO data were complemented with\nground-based observations of the low-J CO lines. We found that the warm\nmolecular gas traced by the mid-J CO transitions has similar physical\nconditions (n_H2 ~ 10^3.2 - 10^3.9 cm^-3 and T_kin ~ 300 - 800 K) in most of\nour galaxies. Furthermore, we found that this warm gas is likely producing the\nmid-IR rotational H2 emission. We could not determine the specific heating\nmechanism of the warm gas, however it is possibly related to the star-formation\nactivity in these galaxies. Our modeling of the [CI] emission suggests that it\nis produced in cold (T_kin < 30 K) and dense (n_H2 > 10^3 cm^-3) molecular gas.\nTransitions of other molecules are often detected in our SPIRE/FTS spectra. The\nHF J=1-0 transition at 1232 GHz is detected in absorption in UGC05101 and in\nemission in NGC7130. In the latter, near-infrared pumping, chemical pumping, or\ncollisional excitation with electrons are plausible excitation mechanisms\nlikely related to the AGN of this galaxy. In some galaxies few H2O emission\nlines are present. Additionally, three OH+ lines at 909, 971, and 1033 GHz are\nidentified in NGC7130." }, { "anchor": "Modeling the role of electron attachment rates on column density ratios\n for CnH-/CnH (n=4,6,8) in dense molecular clouds: (abridged) The fairly recent detection of a variety of anions in the\nInterstellar Molecular Clouds have underlined the importance of realistically\nmodeling the processes governing their abundance. To this aim, our earlier\ncalculations for the radiative electron attachment (REA) rates for C4H-, C6H-,\nand C8H- are employed to generate the corresponding column density ratios of\nanion/neutral (A/N) relative abundances. The latter are then compared with\nthose obtained from observational measurements. The calculations involved the\ntime-dependent solutions of a large network of chemical processes over an\nextended time interval and included a series of runs in which the values of REA\nrates were repeatedly scaled. Macroscopic parameters for the clouds' modeling\nwere also varied to cover a broad range of physical environments. It was found\nthat, within the range and quality of the processes included in the present\nnetwork,and selected from state-of-the-art astrophysical databases, the REA\nvalues required to match the observed A/N ratios needed to be reduced by orders\nof magnitude for C4H- case, while the same rates for C6H- and C8H- only needed\nto be scaled by much smaller factors. The results suggest that the generally\nproposed formation of interstellar anions by REA mechanism is overestimated by\ncurrent models for the C4H- case, for which is likely to be an inefficient path\nto formation. This path is thus providing a rather marginal contribution to the\nobserved abundances of C4H-, the latter being more likely to originate from\nother chemical processes in the network, as we discuss in some detail in the\npresent work.Possible physical reasons for the much smaller differences against\nobservations found instead for the values of the (A/N) ratios in two other,\nlonger members of the series are put forward and analyzed within the\nevolutionary modeling discussed in the present work.", "positive": "Cosmic-ray induced diffusion in interstellar ices: Cosmic rays are able to heat interstellar dust grains. This may enhance\nmolecule mobility in icy mantles that have accumulated on the grains in dark\ncloud cores. A three-phase astrochemical model was used to investigate the\nmolecule mobility in interstellar ices. Specifically, diffusion through pores\nin ice between the subsurface mantle and outer surface, assisted by whole-grain\nheating, was considered. It was found that the pores can serve as an efficient\ntransport route for light species. The diffusion of chemical radicals from the\nmantle to the outer surface are most effective. These species accumulate in the\nmantle because of photodissociation by the cosmic-ray induced photons. The\nfaster diffusion of hydrogen within the warm ice enhances the hydrogenation of\nradicals on pore surfaces. The overall result of the whole grain\nheating-induced radial diffusion in ice are higher abundances of the ice\nspecies whose synthesis involve light radicals. Examples of stable species\nsynthesized this way include the complex organic molecules, OCS, H2O2 and\ncyanoplyynes." }, { "anchor": "Identification of orientation of galaxies in the Galaxy Zoo dataset\n using spectral clustering: This work identifies the orientation of galaxies in the Galaxy zoo data set.\nThe images are first identified by the number of principal components required\nto represent 99 percent of the variance of the image. K means clustering is\nused to separate the galaxies on the basis of their central brightness along\nwith outlier separation. Spectral clustering is then used to separate\ncircularly symmetric galaxies and the remaining galaxies are identified\naccording to their orientation as flat , left and right on the basis of the\nalignment of the main axis. It is also seen that spectral clustering fails to\nmake this classification when the galaxy images are noisy and works only when\napplied on a smaller subset of the total number of images in the Galaxy zoo\ndata set. This method also fails in the presence of multiple galaxies in the\nimage, considering them as an individual entity.", "positive": "Visual Survey of 18020 Objects from the 2MFGC Catalog: We conducted a continuous survey of infrared and visual images of 18020 2MFGC\ngalaxies which were selected on an automatic basis from 1.64 mln extended\nobjects of the 2MASS XSC catalog based on the ratio of the infrared axes\na/b>=3. This work aims to exclude \"false\" objects from the list of flat\ngalaxies. Having observed more than 80 thousand images in different filters, we\nwere able to detect 1512 such objects (8.4% of the total number). We found 23\ngalaxies duplicated in 2MASS, which have two 2MFGC numbers correspondingly, and\nthree flat galaxies which are not included in other catalogs and are located\nclose to three \"false\" galaxies. Galaxies with magnitudes fainter than K_s =13\nmag compose the main part of the excluded objects. They show small angular\nsizes, low surface brightnesses and concentration ratios. The results of the\nwork in the form of the 2MFGC table with notes are given in the astronomical\ndatabases VizieR, NED, HyperLeda." }, { "anchor": "A host galaxy study of southern narrow-line Seyfert 1 galaxies: We studied seven nearby narrow-line Seyfert 1 (NLS1) galaxies in $J$- and\n$Ks$-bands with redshifts varying from 0.019 to 0.092. This is the first\nmulti-source study targeting the hosts of southern NLS1 galaxies. Our data was\nobtained with the FourStar instrument of the 6.5~m Magellan Baade telescope at\nthe Las Campanas Observatory (Chile). The aim of our study is to determine the\nhost galaxy morphologies of these sources by using GALFIT. We were able to\nmodel six out of the seven sources reliably. Our conclusion is that all of the\nreliably modelled sources are disk-like galaxies, either spirals or\nlenticulars. None of these sources present elliptical morphology. Our findings\nare in agreement with the hypothesis that disk-like galaxies are the main host\nof jetted NLS1 galaxies. Taking advantage of observations in two bands, we also\nproduced a $J - Ks$ colour map of each source. Five of the six colour maps show\nsignificant dust extinction near the core of the galaxy -- a feature often seen\nin gamma-ray-detected jetted NLS1 galaxies, and interpreted to be a consequence\nof a past minor merger.", "positive": "The ultra-dense, interacting environment of a dual AGN at z $\\sim$ 3.3\n revealed by JWST/NIRSpec IFS: LBQS 0302-0019 is a blue quasar (QSO) at z ~ 3.3, hosting powerful outflows,\nand residing in a complex environment consisting of an obscured AGN candidate,\nand multiple companions, all within 30 kpc in projection. We use JWST NIRSpec\nIFS observations to characterise the ionized gas in this complex system. We\ndevelop a procedure to correct for the spurious oscillations (or 'wiggles') in\nNIRSpec single-spaxel spectra, due to the spatial under-sampling of the point\nspread function. We perform a quasar-host decomposition with the QDeblend3D\ntools, and use multi-component kinematic decomposition of the optical emission\nline profiles to infer the physical properties of the emitting gas. The\nquasar-host decomposition allows us to identify i) a low-velocity component\npossibly tracing a warm rotating disk, with a dynamical mass Mdyn $\\sim\n10^{11}$ Msun and a rotation-to-random motion ratio $v_{rot}$/$\\sigma_0 \\sim\n2$; ii) a spatially unresolved ionised outflow, with a velocity of $\\sim$ 1000\nkm/s and an outflow mass rate of $\\sim 10^4$ Msun/yr. We also detect eight\ninteracting companion objects close to LBQS 0302-0019. Optical line ratios\nconfirm the presence of a second, obscured AGN at $\\sim 20$ kpc of the primary\nQSO; the dual AGN dominates the ionization state of the gas in the entire\nNIRSpec field-of-view. This work has unveiled with unprecedented detail the\ncomplex environment of this dual AGN, which includes nine interacting\ncompanions (five of which were previously unknown), all within 30 kpc of the\nQSO. Our results support a scenario where mergers can trigger dual AGN, and can\nbe important drivers for rapid early SMBH growth." }, { "anchor": "Dissecting galaxy triplets in the Sloan Digital Sky Survey Data Release\n 10: I. Stellar populations and emission line analysis: We identify isolated galaxy triplets in a volume-limited sample from the\nSloan Digital Sky Survey Data Release 10. Our final sample has 80 galaxy\nsystems in the redshift range 0.04$\\le$z$\\le$0.1, brighter than $M_r = -20.5 +\n5\\log h_{70}$. Spectral synthesis results and WHAN and BPT diagnostic diagrams\nwere employed to classify the galaxies in these systems as star-forming, active\nnuclei, or passive/retired.\n Our results suggest that the brightest galaxies drive the triplet evolution,\nas evidenced by the strong correlations between properties as mass assembly and\nmean stellar population age with triplet properties. Galaxies with intermediate\nluminosity or the faintest one within the triplet seem to play a secondary\nrole. Moreover, the relation between age and stellar mass of galaxies is\nsimilar for these galaxies but different for the brightest galaxy in the\nsystem. Most of the triplet galaxies are passive or retired, according to the\nWHAN classification. Low mass triplets present different fractions of WHAN\nclasses when compared to higher mass triplets. A census of WHAN class\ncombinations shows the dominance of star-forming galaxies in low mass triplets\nwhile retired and passive galaxies prevail in high-mass systems. We argue that\nthese results suggest that the local environment, through galaxy interactions\ndriven by the brightest galaxy, is playing a major role in triplet evolution.", "positive": "Multiple populations within globular clusters in Early-type galaxies\n Exploring their effect on stellar initial mass function estimates: It is now well-established that most (if not all) ancient globular clusters\nhost multiple popula- tions, that are characterised by distinct chemical\nfeatures such as helium abundance variations along with N-C and Na-O\nanti-correlations, at fixed [Fe/H]. These very distinct chemical fea- tures are\nsimilar to what is found in the centres of the massive early-type galaxies and\nmay influence measurements of the global properties of the galaxies.\nAdditionally, recent results have suggested that M/L variations found in the\ncentres of massive early-type galaxies might be due to a bottom-heavy stellar\ninitial mass function. We present an analysis of the effects of globular\ncluster-like multiple populations on the integrated properties of early-type\ngalaxies. In particular, we focus on spectral features in the integrated\noptical spectrum and the global mass-to-light ratio that have been used to\ninfer variations in the stellar initial mass function. To achieve this we\ndevelop appropriate stellar population synthesis models and take into account,\nfor the first time, an initial-final mass relation which takes into\nconsideration a varying He abundance. We conclude that while the multiple\npopulations may be present in massive early-type galaxies, they are likely not\nresponsible for the observed variations in the mass- to-light ratio and IMF\nsensitive line strengths. Finally, we estimate the fraction of stars with\nmultiple populations chemistry that come from disrupted globular clusters\nwithin massive ellipticals and find that they may explain some of the observed\nchemical patterns in the centres of these galaxies." }, { "anchor": "The impact of metallicity and dynamics on the evolution of young star\n clusters: The early evolution of a dense young star cluster (YSC) depends on the\nintricate connection between stellar evolution and dynamical processes. Thus,\nN-body simulations of YSCs must account for both aspects. We discuss N-body\nsimulations of YSCs with three different metallicities (Z=0.01, 0.1 and 1\nZsun), including metallicity-dependent stellar evolution recipes and\nmetallicity-dependent prescriptions for stellar winds and remnant formation. We\nshow that mass-loss by stellar winds influences the reversal of core collapse.\nIn particular, the post-collapse expansion of the core is faster in metal-rich\nYSCs than in metal-poor YSCs, because the former lose more mass (through\nstellar winds) than the latter. As a consequence, the half-mass radius expands\nmore in metal-poor YSCs. We also discuss how these findings depend on the total\nmass and on the virial radius of the YSC. These results give us a clue to\nunderstand the early evolution of YSCs with different metallicity.", "positive": "Bayesian fitting of multi-Gaussian expansion models to galaxy images: Fitting parameterized models to images of galaxies has become the standard\nfor measuring galaxy morphology. This forward modelling technique allows one to\naccount for the PSF to effectively study semi-resolved galaxies. However, using\na specific parameterization for a galaxy's surface brightness profile can bias\nmeasurements if it is not an accurate representation. Furthermore, it can be\ndifficult to assess systematic errors in parameterized profiles. To overcome\nthese issues we employ the Multi-Gaussian expansion (MGE) method of\nrepresenting a galaxy's profile together with a Bayesian framework for fitting\nimages. MGE flexibly represents a galaxy's profile using a series of Gaussians.\nWe introduce a novel Bayesian inference approach which uses pre-rendered\nGaussian components, which greatly speeds up computation time and makes it\nfeasible to run the fitting code on large samples of galaxies. We demonstrate\nour method with a series of validation tests. By injecting galaxies, with\nproperties similar to those observed at $z\\sim1.5$, into deep HST observations\nwe show that it can accurately recover total fluxes and effective radii of\nrealistic galaxies. Additionally we use degraded images of local galaxies to\nshow that our method can recover realistic galaxy surface brightness and color\nprofiles. Our implementation is available in an open source python package\n$\\texttt{imcascade}$, which contains all methods needed for the preparation of\nimages, fitting and analysis of results." }, { "anchor": "Bayesian Inference of Reaction Rates in Icy Mantles: Grain surface chemistry and its treatment in gas-grain chemical models is an\narea of large uncertainty. Whilst laboratory experiments are making progress,\nthere is still much that is unknown about grain surface chemistry. Further, the\nresults and parameters produced by experiment are often not easily translated\nto the rate equation approach most commonly used in astrochemical modelling. It\nis possible that statistical methods can reduce the uncertainty in grain\nsurface chemical networks. In this work, a simple model of grain surface\nchemistry in a molecular cloud is developed and a Bayesian inference of the\nreactions rates is performed through MCMC sampling. Using observational data of\nthe solid state abundances of major chemical species in molecular clouds, the\nposterior distributions for the rates of seven reactions producing CO, CO$_2$,\nCH$_3$OH and H$_2$O are calculated, in a form that is suitable for rate\nequation models. This represents a vital first step in the development of a\nmethod to infer reaction rates from observations of chemical abundances in\nastrophysical environments.", "positive": "Resolved Kinematics of Runaway and Field OB Stars in the Small\n Magellanic Cloud: We use GAIA DR2 proper motions of the RIOTS4 field OB stars in the Small\nMagellanic Cloud (SMC) to study the kinematics of runaway stars. The data\nreveal that the SMC Wing has a systemic peculiar motion relative to the SMC Bar\nof (v_RA, v_Dec) = (62 +/-7, -18+/-5) km/s and relative radial velocity +4.5\n+/- 5.0 km/s. This unambiguously demonstrates that these two regions are\nkinematically distinct: the Wing is moving away from the Bar, and towards the\nLarge Magellanic Cloud with a 3-D velocity of 64 +/- 10 km/s. This is\nconsistent with models for a recent, direct collision between the Clouds. We\npresent transverse velocity distributions for our field OB stars, confirming\nthat unbound runaways comprise on the order of half our sample, possibly more.\nUsing eclipsing binaries and double-lined spectroscopic binaries as tracers of\ndynamically ejected runaways, and high-mass X-ray binaries (HMXBs) as tracers\nof runaways accelerated by supernova kicks, we find significant contributions\nfrom both populations. The data suggest that HMXBs have lower velocity\ndispersion relative to dynamically ejected binaries, consistent with the former\ncorresponding to less energetic supernova kicks that failed to unbind the\ncomponents. Evidence suggests that our fast runaways are dominated by\ndynamical, rather than supernova, ejections." }, { "anchor": "Milky Way demographics with the VVV survey. IV. PSF photometry from\n almost one billion stars in the Galactic bulge and adjacent southern disk: The inner regions of the Galaxy are severely affected by extinction, which\nlimits our capability to study the stellar populations present there. The Vista\nVariables in the Via Lactea (VVV) ESO Public Survey has observed this zone at\nnear-infrared wavelengths where reddening is highly diminished. By exploiting\nthe high resolution and wide field-of-view of the VVV images we aim to produce\na deep, homogeneous, and highly complete database of sources that cover the\ninnermost regions of our Galaxy. To better deal with the high crowding in the\nsurveyed areas, we have used point spread function (PSF)-fitting techniques to\nobtain a new photometry of the VVV images, in the ZYJHKs near-infrared filters\navailable. Our final catalogs contain close to one billion sources, with\nprecise photometry in up to five near-infrared filters, and they are already\nbeing used to provide an unprecedented view of the inner Galactic stellar\npopulations. We make these catalogs publicly available to the community. Our\ncatalogs allow us to build the VVV giga-CMD, a series of color-magnitude\ndiagrams of the inner regions of the Milky Way presented as supplementary\nvideos. We provide a qualitative analysis of some representative CMDs of the\ninner regions of the Galaxy, and briefly mention some of the studies we have\ndeveloped with this new dataset so far.", "positive": "[NeIII]/[OII] as an Ionization Parameter Diagnostic in Star-Forming\n Galaxies: We present our parameterizations of the log([NeIII]3869/[OII]3727) (Ne3O2)\nand log([OIII]5007/[OII]3727) ratios as comparable and effective diagnostics of\nionization parameter in star-forming galaxies. Our calibrations are based on\nthe most recent generations of the Starburst99/Mappings III photoionization\nmodels, which extend up to the extremely high values of ionization parameter\nfound in high-redshift galaxies. While similar calibrations have been presented\npreviously for O3O2, this is the first such calibration of Ne3O2. We illustrate\nthe tight correlation between these two ratios for star-forming galaxies and\ndiscuss the underlying physics that dictates their very similar evolution.\nBased on this work, we propose the Ne3O2 ratio as a new and useful diagnostic\nof ionization parameter for star-forming galaxies. Given the Ne3O2 ratio's\nrelative insensitivity to reddening, this ratio is particularly valuable for\nuse with galaxies that have uncertain amounts of extinction. The short\nwavelengths of the Ne3O2 ratio can also be applied out to very high redshifts,\nextending studies of galaxies' ionization parameters out to z ~ 1.6 with\noptical spectroscopy and z ~ 5.2 with ground-based near-infrared spectra." }, { "anchor": "On the heating of AGN magnetospheres: The Langmuir-Landau-Centrifugal Drive (LLCD), that can effectively \"convert\"\ngravitational energy into particles, is explored as a driving mechanism\nresponsible for the extreme thermal luminosity acquired by some active galactic\nnuclei (AGN). For this purpose we consider equations governing the process of\nheating of AGN magnetospheres. In particular, we examine the Fourier components\nof the momentum equation, the continuity equation and the Poisson equation in\nthe linear approximation and estimate the growth rate of the centrifugally\nexcited electrostatic waves and the increment of the Langmuir collapse. It is\nshown that the process of energy pumping is composed of three stages: in the\nfirst stage the energy is efficiently transferred from rotation to the\nelectrostatic modes. In due course of time, the second regime - the Langmuir\ncollapse - occurs, when energy pumping is even more efficient. This process is\nterminated by the Landau damping, when enormous energy is released in the form\nof heat. We show that the magnetospheres of the supermassive black holes with\nluminosities of the order of $10^{45-46}$erg/s can be heated up to\n$10^{6-10}$K.", "positive": "Extended Gaseous Disk in the S0 galaxy NGC 4143: We present our results of the spectroscopic study of the lenticular galaxy\nNGC 4143 - an outskirt member of the Ursa Major cluster. Using the observations\nat the 6-m SAO RAS telescope with the SCORPIO-2 spectrograph and also the\narchive data of panoramic spectroscopy with the SAURON IFU at the WHT, we have\ndetected an extended inclined gaseous disk which is traced up to a distance of\nabout 3.5 kpc from the center, with a spin approximately opposite to the spin\nof the stellar disk. The galaxy images in the H-alpha and [NII]6583 emission\nlines obtained at the 2.5-m CMO SAI MSU telescope with the MaNGaL instrument\nhave shown that the emission lines are excited by a shock wave. A spiral\nstructure that is absent in the stellar disk of the galaxy is clearly seen in\nthe brightness distribution of ionized-gas lines (H-alpha and [NII] from the\nMaNGaL data and [OIII] from the SAURON data). A complex analysis of both the\nLick index distribution along the radius and of the integrated colors,\nincluding the ultraviolet measurements with the GALEX space telescope and the\nnear-infrared measurements with the WISE space telescope, has shown that there\nhas been no star formation in the galaxy, perhaps, for the last 10 Gyr. Thus,\nthe recent external-gas accretion detected in NGC 4143 from its kinematics, was\nnot accompanied by star formation, probably, due to an inclined direction of\nthe gas inflow onto the disk." }, { "anchor": "Shining Light on the Hosts of the Nano-Hertz Gravitational Wave Sources:\n A Theoretical Perspective: The formation of supermassive black holes (SMBHs) in the Universe and its\nrole in the properties of the galaxies is one of the open questions in\nastrophysics and cosmology. Though, traditionally, electromagnetic waves have\nbeen instrumental in direct measurements of SMBHs, significantly influencing\nour comprehension of galaxy formation, gravitational waves (GW) bring an\nindependent avenue to detect numerous binary SMBHs in the observable Universe\nin the nano-Hertz range using the pulsar timing array observation. This brings\na new way to understand the connection between the formation of binary SMBHs\nand galaxy formation if we can connect theoretical models with multi-messenger\nobservations namely GW data and galaxy surveys. Along these lines, we present\nhere the first paper on this series based on {\\sc Romulus25} cosmological\nsimulation on the properties of the host galaxies of SMBHs and propose on how\nthis can be used to connect with observations of nano-Hertz GW signal and\ngalaxy surveys. We show that the most dominant contribution to the background\nwill arise from sources with high chirp masses which are likely to reside in\nlow redshift early-type galaxies with high stellar mass, largely old stellar\npopulation, and low star formation rate, and that reside at centers of galaxy\ngroups and manifest evidence of recent mergers. The masses of the sources show\na correlation with the halo mass and stellar mass of the host galaxies. This\ntheoretical study will help in understanding the host properties of the GW\nsources and can help in establishing a connection with observations.", "positive": "Excitation of Polycyclic Aromatic Hydrocarbon (PAH) Emission: Dependence\n on Size Distribution, Ionization, and Starlight Spectrum and Intensity: Using physical models, we study the sensitivity of polycyclic aromatic\nhydrocarbon (PAH) emission spectra to the character of the illuminating\nstarlight, to the PAH size distribution, and to the PAH charge distribution.\nStarlight models considered range from the emission from a 3 Myr-old starburst,\nrich in far-ultraviolet (FUV) radiation, to the FUV-poor spectrum of the very\nold population of the M31 bulge. A wide range of starlight intensities is\nconsidered. The effects of reddening in dusty clouds are investigated for\ndifferent starlight spectra. For a fixed PAH abundance parameter $q_{\\rm PAH}$\n(the fraction of the total dust mass in PAHs with $<10^3$ C atoms), the\nfraction of the IR power appearing in the PAH emission features can vary by a\nfactor of two as the starlight spectrum varies from FUV-poor (M31 bulge) to\nFUV-rich (young starburst). We show how $q_{\\rm PAH}$ can be measured from the\nstrength of the 7.7$\\mu$m emission. The fractional power in the 17$\\mu$m\nfeature can be suppressed by high starlight intensities." }, { "anchor": "Co-evolution of black hole accretion and star formation in galaxies up\n to z=3.5: We study the co-evolution between the black hole accretion rate (BHAR) and\nthe star formation rate (SFR) in different galaxy life phases: main sequence\nstar-forming galaxies, quiescent and starburst galaxies at different cosmic\nepochs.\n We take advantage of the X-ray data from the Chandra COSMOS-Legacy survey and\nof the extensive multiwavelength ancillary observations in the COSMOS field\npresented in the COSMOS2015 catalog. We perform an X-ray stacking analysis and\ncombine it with detected sources, in a broad redshift interval ($0.1\n0.8). The [CI]-enhanced regions appear in M-0.02-0.07, the circumnuclear disk,\nthe 180-pc ring and the high velocity compact cloud CO+0.02-0.02. We have\ncarried out a large velocity gradient (LVG) analysis and have derived the\nC^0/CO column density ratio for M-0.02-0.07 as 0.47, which is approximately\ntwice that of the bulk component of the CMZ (0.26). We propose several\nhypotheses on the origin of high C^0 abundance in M-0.02-0.07, including\ncosmic-ray/X-ray dissociation and mechanical dissociation of CO in the\npre-existing molecular clouds. We also suggest the possibility that M-0.02-0.07\nis a cloud at an early stage of chemical evolution from diffuse gas, which was\npossibly formed by the bar-induced mass inflow in the Galactic Center region.", "positive": "A non-equilibrium ortho-to-para ratio of water in the Orion PDR: The ortho-to-para ratio (OPR) of H$_2$O is thought to be sensitive to the\ntemperature of water formation. The OPR of H$_2$O is thus useful to study the\nformation mechanism of water. We investigate the OPR of water in the Orion PDR\n(Photon-dominated region), at the Orion Bar and Orion S positions, using data\nfrom {\\it Herschel}/HIFI. We detect the ground-state lines of ortho- and\npara-H$_2$$^{18}$O in the Orion Bar and Orion S and we estimate the column\ndensities using LTE and non-LTE methods. Based on our calculations, the\northo-to-para ratio (OPR) in the Orion Bar is 0.1 $-$ 0.5, which is\nunexpectedly low given the gas temperature of $\\sim$ 85 K, and also lower than\nthe values measured for other interstellar clouds and protoplanetary disks.\nToward Orion S, our OPR estimate is below 2. This low OPR at 2 positions in the\nOrion PDR is inconsistent with gas phase formation and with thermal evaporation\nfrom dust grains, but it may be explained by photodesorption." }, { "anchor": "Bringing faint active galactic nuclei (AGNs) to light: a view from\n large-scale cosmological simulations: The sensitivity of X-ray facilities and our ability to detect fainter active\ngalactic nuclei (AGNs) will increase with the upcoming Athena mission and the\nAXIS and Lynx concept missions, thus improving our understanding of\nsupermassive black holes (BHs) in a luminosity regime that can be dominated by\nX-ray binaries. We analyze the population of faint AGN (L_x (2-10 keV) < 10^42\nerg/s) in the Illustris, TNG100, EAGLE, and SIMBA cosmological simulations, and\nfind that the properties of their host galaxies vary from one simulation to\nanother. In Illustris and EAGLE, faint AGN are powered by low-mass BHs located\nin low-mass star-forming galaxies. In TNG100 and SIMBA, they are mostly\nassociated with more massive BHs in quenched massive galaxies. We model the\nX-ray binary populations (XRB) of the simulated galaxies, and find that AGN\noften dominate the galaxy AGN+XRB hard X-ray luminosity at z>2, while XRBs\ndominate in some simulations at z<2. Whether the AGN or XRB emission dominates\nin star-forming and quenched galaxies depends on the simulations. These\ndifferences in simulations can be used to discriminate between galaxy formation\nmodels with future high-resolution X-ray observations. We compare the\nluminosity of simulated faint AGN host galaxies to observations of stacked\ngalaxies from Chandra. Our comparison indicates that the simulations\npost-processed with our X-ray modeling tend to overestimate the AGN+XRB X-ray\nluminosity; luminosity that can be strongly affected by AGN obscuration. Some\nsimulations reveal clear AGN trends as a function of stellar mass (e.g., galaxy\nluminosity drop in massive galaxies), which are not apparent in the\nobservations.", "positive": "8 in 10 Stars in the Milky Way Bulge Experience Stellar Encounters\n Within 1000 AU in a Gigayear: The Galactic bulge is a tumultuous dense region of space, packed with stars\nseparated by far smaller distances than those in the Solar neighborhood. A\nquantification of the frequency and proximity of close stellar encounters in\nthis environment dictates the exchange of material, disruption of planetary\norbits, and threat of sterilizing energetic events. We present estimated\nencounter rates for stars in the Milky Way bulge found using a combination of\nnumerical and analytical methods. By integrating the orbits of bulge stars with\nvarying orbital energy and angular momentum to find their positions over time,\nwe were able to estimate how many close stellar encounters the stars should\nexperience as a function of orbit shape. We determined that ~80% of bulge stars\nhave encounters within 1000 AU and that half of bulge stars will have >35 such\nencounters, both over a gigayear. Our work has interesting implications for the\nlong-term survivability of planets in the Galactic bulge." }, { "anchor": "The Galactic WC and WO stars: The impact of revised distances from Gaia\n DR2 and their role as massive black hole progenitors: Wolf-Rayet stars of the carbon sequence (WC stars) are an important\ncornerstone in the late evolution of massive stars before their core collapse.\nAs core-helium burning, hydrogen-free objects with huge mass-loss, they are\nlikely the last observable stage before collapse and thus promising progenitor\ncandidates for type Ib/c supernovae. Their strong mass-loss furthermore\nprovides challenges and constraints to the theory of radiatively driven winds.\nThus, the determination of the WC star parameters is of major importance for\nseveral astrophysical fields. With Gaia DR2, for the first time parallaxes for\na large sample of Galactic WC stars are available, removing major uncertainties\ninherent to earlier studies. In this work, we re-examine the sample from Sander\net al. (2012) to derive key properties of the Galactic WC population. All\nquantities depending on the distance are updated, while the underlying spectral\nanalyses remain untouched. Contrasting earlier assumptions, our study yields\nthat WC stars of the same subtype can significantly vary in absolute magnitude.\nWith Gaia DR2, the picture of the Galactic WC population becomes more complex:\nWe obtain luminosities ranging from log L = 4.9 to 6.0 with one outlier having\nlog L = 4.7. This indicates that the WC stars are likely formed from a broader\ninitial mass range than previously assumed. We obtain mass-loss rates ranging\nbetween log Mdot = -5.1 and -4.1, with Mdot propto L^0.68 and a linear scaling\nof the modified wind momentum with luminosity. We discuss the implications for\nstellar evolution, including unsolved issues regarding the need of envelope\ninflation to address the WR radius problem, and the open questions in regard to\nthe connection of WR stars with Gamma-ray bursts. WC and WO stars are\nprogenitors of massive black holes, collapsing either silently or in a\nsupernova that most-likely has to be preceded by a WO stage.", "positive": "A Massive, Clumpy Molecular Gas Distribution and Displaced AGN in Zw\n 3146: We present a recent ALMA observation of the CO(1-0) line emission in the\ncentral galaxy of the Zw 3146 galaxy cluster ($z=0.2906$). We also present\nupdated X-ray cavity measurements from archival Chandra observations. The\n$5\\times 10^{10}\\,M_{\\odot}$ supply of molecular gas, which is confined to the\ncentral 4 kpc, is marginally resolved into three extensions that are\nreminiscent of the filaments observed in similar systems. No velocity structure\nthat would be indicative of ordered motion is observed. The three molecular\nextensions all trail X-ray cavities, and are potentially formed from the\ncondensation of intracluster gas lifted in the wakes of the rising bubbles.\nMany cycles of feedback would be require to account for the entire molecular\ngas reservoir. The molecular gas and continuum source are mutually offset by\n2.6 kpc, with no detected line emission coincident with the continuum source.\nIt is the molecular gas, not the continuum source, that lies at the\ngravitational center of the brightest cluster galaxy. As the brightest cluster\ngalaxy contains possible tidal features, the displaced continuum source may\ncorrespond to the nucleus of a merging galaxy. We also discuss the possibility\nthat a gravitational wave recoil following a black hole merger may account for\nthe displacement." }, { "anchor": "Characterising abundance-age relations of GALAH stars using\n oxygen-enhanced stellar models: Main Sequence Turn-off stars (MSTO) and subgiant stars are good tracers of\ngalactic populations. We present a study of 41,034 MSTO and subgiant stars from\nthe GALAH survey. Using a grid of stellar models that accounts for the\nvariation of O abundances, we determine their ages with a median age\nuncertainty of $\\sim$9.4 per cent. Our analysis reveals that the ages of high-O\nstars based on O-enhanced models (OEM models) are smaller than those determined\nwith $\\alpha$-enhanced models, resulting in a mean fractional age difference of\n-5.3 per cent at [O/$\\alpha$] = 0.2 and -11.0 per cent at [O/$\\alpha$] = 0.4.\nThis age difference significantly impacts the age distribution of thick disc\nand halo stars, leading to a steeper downward trend in the [Fe/H]-age plane\nfrom 8 Gyr to 14 Gyr, indicating a shorter formation time-scale and a faster\nchemical-enhanced history for these populations. We confirm the V-shape of the\nnormalized age-metallicity distribution $p$($\\tau$$\\mid$[Fe/H]) of thin disc\nstars, which is presumably a consequence of the second gas infall.\nAdditionally, we find that the halo stars in our sample can be divided into two\nsequences, a metal-rich sequence (Splash stars) and a metal-poor sequence\n(accreted stars), with the Splash stars predominantly older than 9 Gyr and the\naccreted halo stars older than 10 Gyr. Finally, we observe two distinct\nsequences in the relations between various chemical abundances and age for disc\nstars, namely a young sequence with ages $<$ $\\sim$8 Gyr and an old sequence\nwith ages $>$ $\\sim$8 Gyr.", "positive": "The intrinsic three-dimensional shape of galactic bars: We present the first statistical study on the intrinsic three-dimensional\n(3D) shape of a sample of 83 galactic bars extracted from the CALIFA survey. We\nuse the galaXYZ code to derive the bar intrinsic shape with a statistical\napproach. The method uses only the geometric information (ellipticities and\nposition angles) of bars and discs obtained from a multi-component photometric\ndecomposition of the galaxy surface-brightness distributions. We find that bars\nare predominantly prolate-triaxial ellipsoids (68%), with a small fraction of\noblate-triaxial ellipsoids (32%). The typical flattening (intrinsic C/A\nsemiaxis ratio) of the bars in our sample is 0.34, which matches well the\ntypical intrinsic flattening of stellar discs at these galaxy masses. We\ndemonstrate that, for prolate-triaxial bars, the intrinsic shape of bars\ndepends on the galaxy Hubble type and stellar mass (bars in massive S0 galaxies\nare thicker and more circular than those in less massive spirals). The bar\nintrinsic shape correlates with bulge, disc, and bar parameters. In particular\nwith the bulge-to-total (B/T) luminosity ratio, disc g-r color, and central\nsurface brightness of the bar, confirming the tight link between bars and their\nhost galaxies. Combining the probability distributions of the intrinsic shape\nof bulges and bars in our sample we show that 52% (16%) of bulges are thicker\n(flatter) than the surrounding bar at 1$\\sigma$ level. We suggest that these\npercentages might be representative of the fraction of classical and disc-like\nbulges in our sample, respectively." }, { "anchor": "Connecting low- and high-mass star formation: the intermediate-mass\n protostar IRAS 05373+2349 VLA 2: Until recently, there have been few studies of the protostellar evolution of\nintermediate-mass (IM) stars, which may bridge the low- and high-mass regimes.\nThis paper aims to investigate whether the properties of an IM protostar within\nthe IRAS 05373+2349 embedded cluster are similar to that of low- and/or\nhigh-mass protostars. We carried out Very Large Array as well as Combined Array\nfor Research in Millimeter Astronomy continuum and 12CO(J=1-0) observations,\nwhich uncover seven radio continuum sources (VLA 1-7). The spectral index of\nVLA 2, associated with the IM protostar is consistent with an ionised stellar\nwind or jet. The source VLA 3 is coincident with previously observed H2\nemission line objects aligned in the north-south direction (P.A. -20 to -12\ndeg), which may be either an ionised jet emanating from VLA 2 or\n(shock-)ionised cavity walls in the large-scale outflow from VLA 2. The\nposition angle between VLA 2 and 3 is slightly misaligned with the large-scale\noutflow we map at ~5-arcsec resolution in 12CO (P.A. ~30 deg), which in the\ncase of a jet suggests precession. The emission from the mm core associated\nwith VLA 2 is also detected; we estimate its mass to be 12-23 Msun, depending\non the contribution from ionised gas. Furthermore, the large-scale outflow has\nproperties intermediate between outflows from low- and high-mass young stars.\nTherefore, we conclude that the IM protostar within IRAS 05373+2349 is\nphenomenologically as well as quantitatively intermediate between the low- and\nhigh-mass domains.", "positive": "Direct observations of the atomic-molecular phase transition in the\n Milky Way's nuclear wind: Hundreds of high-velocity atomic gas clouds exist above and below the\nGalactic Centre, with some containing a molecular component. However, the\norigin of these clouds in the Milky Way's wind is unclear. This paper presents\nnew high-resolution MeerKAT observations of three atomic gas clouds and studies\nthe relationship between the atomic and molecular phases at $\\sim 1$ pc scales.\nThe clouds' atomic hydrogen column densities, $N_{\\mathrm{HI}}$, are less than\na $\\mbox{few}\\times 10^{20}$ cm$^{-2}$, but the two clouds closest to the\nGalactic Centre nonetheless have detectable CO emission. This implies the\npresence of H$_{2}$ at levels of $N_{\\mathrm{HI}}$ at least a factor of ten\nlower than in the typical Galactic interstellar medium. For the cloud closest\nto the Galactic Centre, there is little correlation between the\n$N_{\\mathrm{HI}}$ and the probability that it will harbour detectable CO\nemissions. In contrast, for the intermediate cloud, detectable CO is heavily\nbiased toward the highest values of $N_{\\mathrm{HI}}$. The cloud most distant\nfrom the Galactic Centre has no detectable CO at similar $N_{\\mathrm{HI}}$\nvalues. Moreover, we find that the two clouds with detectable CO are too\nmolecule-rich to be in chemical equilibrium, given the depths of their atomic\nshielding layers, which suggests a scenario whereby these clouds consist of\npre-existing molecular gas from the disc that the Galactic wind has swept up,\nand that is dissociating into atomic hydrogen as it flows away from the Galaxy.\nWe estimate that entrained molecular material of this type has a $\\sim\n\\mathrm{few}-10$ Myr lifetime before photodissociating." }, { "anchor": "Fe III emission in quasars: evidence for a dense turbulent medium: Recent improvements to atomic energy-level data allow, for the first time,\naccurate predictions to be made for the Fe III line emission strengths in the\nspectra of luminous, $L_\\text{bol}=10^{46}-10^{48}$ erg/s, Active Galactic\nNuclei. The Fe III emitting gas must be primarily photoionized, consistent with\nobservations of line reverberation. We use CLOUDY models exploring a wide range\nof parameter space, together with 26,500 rest-frame ultraviolet spectra from\nthe Sloan Digital Sky Survey, to constrain the physical conditions of the line\nemitting gas. The observed Fe III emission is best accounted for by dense\n($n_H=10^{14}$ cm$^{-3}$) gas which is microturbulent, leading to smaller line\noptical depths and fluorescent excitation. Such high density gas appears to be\npresent in the central regions of the majority of luminous quasars. Using our\nfavoured model, we present theoretical predictions for the relative strengths\nof the Fe III UV34 $\\lambda\\lambda$1895,1914,1926 multiplet. This multiplet is\nblended with the Si III] $\\lambda$1892 and C III] $\\lambda$1909 emission lines\nand an accurate subtraction of UV34 is essential when using these lines to\ninfer information about the physics of the broad line region in quasars.", "positive": "Testing the Tremaine-Weinberg Method Applied to Integral-field\n Spectroscopic Data Using a Simulated Barred Galaxy: Tremaine and Weinberg (TW) proposed a conceptually simple procedure relying\non long-slit spectroscopy to measure the pattern speeds of bars ($\\Omega_{\\rm\np}$) in disk galaxies. Using a simulated galaxy, we investigate the potential\nbiases and uncertainties of TW measurements using increasingly popular\nintegral-field spectrographs (IFSs), for which multiple pseudo-slits (and thus\nindependent measurements) can be constructed with a single observation. Most\nimportant, to establish the spatial coverage required and ensure the validity\nof the measurements, the inferred $\\Omega_{\\rm p}$ must asymptotically converge\nas the (half-)length of each pseudo-slit used is increased. The requirement for\nour simulation is to reach $\\approx1.3$ times the half-light radius, but this\nmay vary from galaxy to galaxy. Only those slits located within the bar region\nyield accurate measurements. We confirm that the position angle of the disk is\nthe dominant source of systematic error in TW $\\Omega_{\\rm p}$ measurements,\nleading to under/overestimates of tens of percents for inaccuracies of even a\nfew degrees. Recasting the data so that the data grid aligns with the disk\nmajor axis leads to slightly reduced uncertainties. Accurate measurements are\nobtained only for well-defined ranges of the bar angle (relative to the galaxy\nmajor axis) $\\phi_{\\rm bar}$ and the inclination angle $i$, here\n$10\\lesssim\\phi_{\\rm bar}\\lesssim75^{\\circ}$ and $105\\lesssim\\phi_{\\rm\nbar}\\lesssim170^{\\circ}$ and $15\\lesssim i\\lesssim70^{\\circ}$. The adopted\n(pseudo-)slit widths, spatial resolution, and (unless extremely aggressive)\nspatial binning of IFS data have no significant impact on the measurements. Our\nresults thus provide useful guidelines for reliable and accurate direct\n$\\Omega_{\\rm p}$ measurements with IFS observations." }, { "anchor": "Galactic planetary nebulae in the AKARI far-infrared surveyor bright\n source catalog: We present the results of our preliminary study of all known Galactic PNe\n(included in the Kerber 2003 catalog) which are detected by the AKARI/FIS\nAll-Sky Survey as identified in the AKARI/FIS Bright Source Catalog (BSC)\nVersion Beta-1.", "positive": "The Physical Properties of Low Redshift FeLoBAL Quasars. I. Spectral\n Synthesis Analysis of the BAL Outflows using $SimBAL$: We present the first systematic study of 50 low redshift ($0.66 < z < 1.63$)\niron low-ionization broad absorption-line quasars (FeLoBALQs) using $SimBAL$\nwhich represents a more than five-fold increase in the number of FeLoBALQs with\ndetailed absorption line spectral analyses. We found the outflows have a wide\nrange of ionization parameters, $-4\\lesssim\\log U\\lesssim 1.2$ and densities,\n$2.8\\lesssim\\log n\\lesssim8\\ \\rm[cm^{-3}]$. The objects in our sample showed\nFeLoBAL gas located at a wide range of distances $0\\lesssim\\log R\\lesssim 4.4$\n[pc], although we do not find any evidence for disk winds (with $R\\ll0.01$ pc)\nin our sample. The outflow strength primarily depends on the outflow velocity\nwith faster outflows found in quasars that are luminous or that have flat or\nredder spectral energy distributions. We found that $\\sim18\\%$ of the FeLoBALQs\nin the sample have the significantly powerful outflows needed for quasar\nfeedback. Eight objects showed \"overlapping troughs\" in the spectra and we\nidentified eleven \"loitering outflow\" objects, a new class of FeLoBALQs that\nare characterized by low outflow velocities and high column density winds\nlocated $\\log R\\lesssim1$ [pc] from the central engine. The FeLoBALs in\nloitering outflows objects do not show properties expected for radiatively\ndriven winds and these objects may represent a distinct population among\nFeLoBALQs. We discuss how the potential acceleration mechanisms and the origins\nof the FeLoBAL winds may differ for outflows at different locations in quasars." }, { "anchor": "Low Frequency Two Meter Sky Survey Radial Artifacts Identified as BL\n Quasars: Through the use of a High Band Antenna system, the Low Frequency Array\nTwo-Meter Sky Survey (LoTSS) is an attempt to complete a high-resolution survey\nof the northern celestial sky. To date, thousands of radio sources have been\nclassified by LOFAR with most of them consisting of active galactic nuclei\n(AGN). The strong AGN emissions detected by LoTSS, it is thought, are powered\nby supermassive black holes (SMBHs) at the center of galaxies. During an\nanalysis of 1500 images of these AGNs, we identified 10 radio sources with\nradial spokes emitted from an unknown source. According to LOFAR, the radial\nspokes are artifacts due to calibration errors with no origin, and therefore\nthey cannot be associated with an optical source. Our preliminary hypothesis\nfor the artifacts was that they were produced by ionized jets emitted from\nquasi-stellar objects (QSOs). Specifically, that strong emissions from Type 1\nbroadline (BL) quasars were directed in the line of sight of the observer\n(i.e., LOFAR) and as a result produced the image artifacts. To test our\nhypotheses, we cross-referenced the ra and dec coordinates of the artifacts\nwith the galactic coordinates indexed in the Sloan Digital Sky Survey (SDSS)\nand confirmed that the artifacts were associated with BL QSOs. Further analysis\nof the QSOs, moreover, demonstrated they exhibited prominent broad emission\nlines such as CIII and MgII, which are characteristic of Type 1 BL quasars. It\nis our interpretation, therefore, that the radial spokes characterized as\nartifacts by LOFAR were produced by the emission of Type 1 BL quasars in the\nline of sight of the radio telescope.", "positive": "Early Science with the Large Millimeter Telescope: a 1.1 mm AzTEC Survey\n of Red-$Herschel$ dusty star-forming galaxies: We present LMT/AzTEC 1.1mm observations of $\\sim100$ luminous high-redshift\ndusty star-forming galaxy candidates from the $\\sim600\\,$sq.deg\n$Herschel$-ATLAS survey, selected on the basis of their SPIRE red far-infrared\ncolours and with $S_{500\\mu\\rm m}=35-80$ mJy. With an effective $\\theta_{\\rm\nFWHM}\\approx9.5\\,$ arcsec angular resolution, our observations reveal that at\nleast 9 per cent of the targets break into multiple systems with SNR $\\geq 4$\nmembers. The fraction of multiple systems increases to $\\sim23\\,$ per cent (or\nmore) if some non-detected targets are considered multiples, as suggested by\nthe data. Combining the new AzTEC and deblended $Herschel$ photometry we derive\nphotometric redshifts, IR luminosities, and star formation rates. While the\nmedian redshifts of the multiple and single systems are similar $(z_{\\rm\nmed}\\approx3.6)$, the redshift distribution of the latter is skewed towards\nhigher redshifts. Of the AzTEC sources $\\sim85\\,$ per cent lie at $z_{\\rm\nphot}>3$ while $\\sim33\\,$ per cent are at $z_{\\rm phot}>4$. This corresponds to\na lower limit on the space density of ultra-red sources at $44$\ngalaxies." }, { "anchor": "Formation and evolution of the local interstellar environment: combined\n constraints from nucleosynthetic and X-ray data: Several observations suggest that the Solar system has been located in a\nregion affected by massive stellar feedback for at least a few Myr; these\ninclude detection of live $^{60}\\text{Fe}$ in deep-sea archives and Antarctic\nsnow, the broad angular distribution of $^{26}\\text{Al}$ around the Galactic\nplane seen in all-sky $\\gamma$-ray maps, and the all-sky soft X-ray background.\nHowever, our position inside the Galactic disc makes it difficult to fully\ncharacterise this environment, and our limited time baseline provides no\ninformation about its formation history or relation to large-scale Galactic\ndynamics. We explore these questions by using an $N$-body+hydrodynamics\nsimulation of a Milky-Way-like galaxy to identify stars on Sun-like orbits\nwhose environments would produce conditions consistent with those we observe.\nWe find that such stars are uncommon but not exceptionally rare. These stars\nare found predominantly near the edges of spiral arms, and lie inside kpc-scale\nbubbles that are created by multiple generations of star formation in the arm.\nWe investigate the stars' trajectories and find that the duration of the stay\nin the bubble ranges from 20 Myr to 90 Myr. The duration is governed by the\ncrossing time of stars across the spiral arm. This is generally shorter than\nthe bubble lifetime, which is $\\sim 100$ Myr as a result of the continuous gas\nsupply provided by the arm environment.", "positive": "Studying the evolution of galaxies in compact groups over the past 3 Gyr\n - II. The importance of environment in the suppression of star formation: We present an in depth study on the evolution of galaxy properties in compact\ngroups over the past 3 Gyr. We are using the largest multi-wavelength sample\nto-date, comprised 1770 groups (containing 7417 galaxies), in the redshift\nrange of 0.01 4 A) and emission line flux ratios. We perform\nfar-infrared (FIR) stacking analyses by splitting the SDSS SF galaxy sample\naccording to their stellar mass, specific SFR (SSFR_SDSS), and environment. We\nderive total infrared luminosity (LIR) for each subsample using the average\nflux densities at WIDE-S (90 micron) and WIDE-L (140 micron) bands, and then\ncompute IR-based SFR (SFR_IR) from L_IR. We find a mild decrease of IR- based\nSSFR (SSFR_IR) amongst SF galaxies with increasing local density (~0.1-dex\nlevel at maximum), which suggests that environmental effects do not instantly\nshut down the SF activity in galaxies. We also derive average dust temperature\n(T_dust) using the flux densities at 90 micron and 140 micron bands. We confirm\na strong positive correlation between T_dust and SSFR_IR, consistent with\nrecent studies. The most important finding of this study is that we find a\nmarginal trend that T_dust increases with increasing environmental galaxy\ndensity. Although the environmental trend is much milder than the SSFR-T_dust\ncorrelation, our results suggest that the environmental density may affect the\ndust temperature in SF galaxies, and that the physical mechanism which is\nresponsible for this phenomenon is not necessarily specific to cluster\nenvironments because the environmental dependence of T_dust holds down to\nrelatively low-density environments." }, { "anchor": "First Detection of Interaction between a Magnetic Disk Wind and an\n Episodic Jet in a Protostellar System: Rotating outflows from protostellar disks might trace extended\nmagneto-hydrodynamic (MHD) disk winds (DWs), providing a solution to the\nangular momentum problem in disk accretion for star formation. In the jet\nsystem HH 212, a rotating outflow was detected in SO around an episodic jet\ndetected in SiO. Here we spatially resolve this SO outflow into three\ncomponents: a collimated jet aligned with the SiO jet, the wide-angle disk\noutflow, and an evacuated cavity in between created by a large jet-driven\nbowshock. Although it was theoretically predicted before, it is the first time\nthat such a jet-DW interaction is directly observed and resolved, and it is\ncrucial for the proper interpretation and modeling of non-resolved DW\ncandidates. The resolved kinematics and brightness distribution both support\nthe wide-angle outflow to be an extended MHD DW dominating the local angular\nmomentum extraction out to 40 au, but with an inner launching radius truncated\nto $\\gtrsim 4$ au. Inside 4 au, where the DW may not exist, the\nmagneto-rotational instability (MRI) might be transporting angular momentum\noutwards. The jet-DW interaction in HH 212, potentially present in other\nsimilar systems, opens an entirely new avenue to probe the large-scale magnetic\nfield in protostellar disks.", "positive": "Physical and Chemical Properties of Galactic Global Clusters with\n Various Origins Identified from the Gaia DR2 Data: The differences in the relationships between the physical parameters and the\nchemical-element abundances in accreted globular star clusters and those formed\ninside the Galaxy have been investigated. The information on the supposed\nformation sites of the clusters based on the Gaia~DR2 data is borrowed from the\nliterature. Those sources estimate the probability of belonging to the Galactic\nbulge and disk, as well as to six known events of the merger of dwarf satellite\ngalaxies with the Milky Way, for 151~globular clusters. It is shown that all\nmetal-poor ($\\rm{[Fe/H]}<-1.0$) genetically related globular clusters have high\nrelative abundances of $\\alpha$-elements. According to modern views, since type\nII supernovae release more $\\alpha$-elements into the interstellar medium with\nincreasing mass, it has been suggested that masses of type II supernovae in the\nGalaxy were greater than in the accreted galaxies. It is proved that the\nclusters of the low-energy group, which were considered accreted, are\ngenetically related to a single protogalactic cloud, same as the unstratified\nclusters UKS~1 and Liller~1, which most likely belong to the bulge. It is shown\nthat not only the lower but also the upper limits of the clusters' masses\ndecrease with an increase in the average radius of their orbits. The latter\nfact is explained by a decrease in the masses of emerging clusters with a\ndecrease in the masses of their host galaxies. It is demonstrated that an\nextremely multicomponent stellar population is observed only in accreted\nglobular clusters with an initial mass $>10^{6}M_{\\odot}$. It has been\nsuggested that these clusters retained all the matter ejected by their evolved\nstars, from which new generations of stars formed due to long evolution far\nfrom our Galaxy." }, { "anchor": "Detection of a high-mass prestellar core candidate in W43-MM1: Aims. To constrain the physical processes that lead to the birth of high-mass\nstars it is mandatory to study the very first stages of their formation. We\nsearch for high-mass analogs of low-mass prestellar cores in W43-MM1.\n Methods. We conducted a 1.3 mm ALMA mosaic of the complete W43-MM1 cloud,\nwhich has revealed numerous cores with ~ 2000 au FWHM sizes. We investigated\nthe nature of cores located at the tip of the main filament, where the\nclustering is minimum. We used the continuum emission to measure the core\nmasses and the $^{13}$CS(5-4) line emission to estimate their turbulence level.\nWe also investigated the prestellar or protostellar nature of these cores by\nsearching for outflow signatures traced by CO(2-1) and SiO(5-4) line emission,\nand for molecular complexity typical of embedded hot cores.\n Results. Two high-mass cores of ~ 1300 au diameter and ~ $60~M_\\odot$ mass\nare observed to be turbulent but gravitationally bound. One drives outflows and\nis associated with a hot core. The other core, W43-MM1\\#6, does not yet reveal\nany star formation activity and thus is an excellent high-mass prestellar core\ncandidate.", "positive": "Infall and outflow within 400 AU from a high-mass protostar. 3-D\n velocity fields from methanol and water masers in AFLG 5142: Observational signatures of infalling envelopes and outflowing material in\nearly stages of protostellar evolution, and at small radii from the protostar,\nare essential to progress in the understanding of the mass-accretion process in\nstar formation. In this letter, we report a detailed study of the accretion and\noutflow structure around a protostar in the well-known high-mass star-forming\nregion AFGL 5142. We focus on the mm source MM-1, which exhibits hot-core\nchemistry, radio continuum emission, and strong water and methanol masers.\nRemarkably, our Very Long Baseline Interferometry (VLBI) observations of\nmolecular masers over six years provided us with the 3-D velocity field of\ncircumstellar molecular gas with a resolution of 0.001-0.005 arcseconds and at\nradii <0.23 arcseconds (or 400 AU) from the protostar. In particular, our\nmeasurements of methanol maser emission enabled, for the first time, a direct\nmeasurement of infall of a molecular envelope (radius of 300 AU and velocity of\n5 km/s) onto an intermediate- to high-mass protostar. We estimate an infall\nrate of 0.0006 n_8 Msun/year, where n_8 is the ambient volume density in units\nof 10^8 cm-3 (required for maser excitation). In addition, our measurements of\nwater maser (and radio continuum) emission identify a collimated bipolar\nmolecular outflow (and ionized jet) from MM-1. The evidence of simultaneous\naccretion and outflow at small spatial scales, makes AFGL 5142 an extremely\ncompelling target for high-angular resolution studies of high-mass star\nformation." }, { "anchor": "Spatial distribution of dark matter in and around galaxy clusters traced\n by galaxies, gas and intracluster stars in a simulated universe: To understand how well galaxies, gas and intracluster stars trace dark matter\nin and around galaxy clusters, we use the IllustrisTNG cosmological\nhydrodynamical simulation and compare the spatial distribution of dark matter\nwith those of baryonic components in clusters. To quantify the global\nmorphology of the density distribution of each component in clusters, we fit an\nellipse to the density contour of each component and derive shape parameters at\ndifferent radii. We find that ellipticity of dark matter is better correlated\nwith that of galaxy mass-weighted number density, rather than with that of\ngalaxy number density or galaxy velocity dispersion. We thus use the galaxy\nmass-weighted number density map as a representative of the galaxy maps. Among\nthree different density maps from galaxies, gas, and intracluster stars, the\nellipticity of dark matter is best reproduced by that of the galaxy map over\nthe entire radii. The 'virialized' galaxy clusters show a better correlation of\nspatial distribution between dark matter and other components than the\n'unvirialized' clusters, suggesting that it requires some time for each\ncomponent to follow the spatial distribution of dark matter after merging\nevents. Our results demonstrate that galaxies are still good tracers of dark\nmatter distribution even in the non-linear regime corresponding to the scales\nin and around galaxy clusters, being consistent with the case where galaxies\ntrace well the matter distribution in cosmologically large scales.", "positive": "X-ray observations of PSR B1259-63 near the 2007 periastron passage: PSR B1259-63 is a 48 ms radio pulsar in a highly eccentric 3.4 year orbit\nwith a Be star SS 2883. Unpulsed gamma-ray, X-ray and radio emission components\nare observed from the binary system. It is likely that the collision of the\npulsar wind with the anisotropic wind of the Be star plays a crucial role in\nthe generation of the observed non-thermal emission. The 2007 periastron\npassage was observed in unprecedented details with Suzaku, Swift, XMM-Newton\nand Chandra missions. We present here the results of this campaign and compare\nthem with previous observations. With these data we are able, for the first\ntime, to study the details of the spectral evolution of the source over a 2\nmonths period of the passage of the pulsar close to the Be star. New data\nconfirm the pre-periastron spectral hardening, with the photon index reaching a\nvalue smaller than 1.5, observed during a local flux minimum. If the observed\nX-ray emission is due to the inverse Compton (IC) losses of the 10 MeV\nelectrons, then such a hard spectrum can be a result of Coulomb losses, or can\nbe related to the existence of the low-energy cut-off in the electron spectrum.\nAlternatively, if the X-ray emission is a synchrotron emission of very high\nenergy electrons, the observed hard spectrum can be explained if the high\nenergy electrons are cooled by IC emission in Klein-Nishina regime.\nUnfortunately the lack of simultaneous data in the TeV energy band prevents us\nfrom making a definite conclusion on the nature of the observed spectral\nhardening and, therefore, on the origin of the X-ray emission." }, { "anchor": "Cloud-cloud collision in S235: triggered the formation of high-mass\n stars and young star clusters: We present the analysis of cloud-cloud collision (CCC) process in the\nGalactic molecular complex S235. Our new CO observations performed with the\nPMO-13.7m telescope reveal two molecular clouds, namely the S235-Main and the\nS235-ABC, with $\\sim$ 4 km s$^{-1}$ velocity separation. The bridge feature,\nthe possible colliding interface and the complementary distribution of the two\nclouds are significant observational signatures of cloud-cloud collision in\nS235. The most direct evidence of cloud-cloud collision process in S235 is that\nthe S235-Main (in a distance of 1547$^{+44}_{-43}$ pc) and S235-ABC\n(1567$^{+33}_{-39}$ pc) meet at almost the same position (within 1$\\sigma$\nerror range) at a supersonic relative speed. We identified ten $^{13}$CO clumps\nfrom PMO-13.7m observations, 22 dust cores from the archival SCUBA-2 data, and\n550 YSOs from NIR-MIR data. 63$\\%$ of total YSOs are clustering in seven MST\ngroups (M1$-$M7). The tight association between the YSO groups (M1 $\\&$ M7) and\nthe bridge feature suggests that the CCC process triggers star formation there.\nThe collisional impact subregion (the South) shows $3\\sim5$ times higher CFE\nand SFE (average value of 12.3$\\%$ and 10.6$\\%$, respectively) than the\nnon-collisional impact subregion (2.4$\\%$ and 2.6$\\%$, respectively),\nsuggesting that the CCC process may have enhanced the CFE and SFE of the clouds\ncompared to those without collision influence.", "positive": "A rotational and vibrational investigation of phenylpropiolonitrile\n (C$_6$H$_5$C$_3$N): The evidence for benzonitrile (C$_6$H$_5$CN}) in the starless cloud core\nTMC-1 makes high-resolution studies of other aromatic nitriles and their\nring-chain derivatives especially timely. One such species is\nphenylpropiolonitrile (3-phenyl-2-propynenitrile, C$_6$H$_5$C$_3$N), whose\nspectroscopic characterization is reported here for the first time. The low\nresolution (0.5 cm$^{-1}$) vibrational spectrum of C$_6$H$_5$C$_3$N} has been\nrecorded at far- and mid-infrared wavelengths (50 - 3500 cm$^{-1}$) using a\nFourier Transform interferometer, allowing for the assignment of band centers\nof 14 fundamental vibrational bands. The pure rotational spectrum of the\nspecies has been investigated using a chirped-pulse Fourier transform microwave\n(FTMW) spectrometer (6 - 18 GHz), a cavity enhanced FTMW instrument (6 - 20\nGHz), and a millimeter-wave one (75 - 100 GHz, 140 - 214 GHz). Through the\nassignment of more than 6200 lines, accurate ground state spectroscopic\nconstants (rotational, centrifugal distortion up to octics, and nuclear\nquadrupole hyperfine constants) have been derived from our measurements, with a\nplausible prediction of the weaker bands through calculations. Interstellar\nsearches for this highly polar species can now be undertaken with confidence\nsince the astronomically most interesting radio lines have either been measured\nor can be calculated to very high accuracy below 300 GHz." }, { "anchor": "Study of Milli-Jansky Seyfert Galaxies with Strong Forbidden\n High-Ionization Lines Using the Very Large Array Survey Images: We study the radio properties at 1.4 GHz of Seyfert galaxies with strong\nforbidden high-ionization lines (FHILs), selected from the Sloan Digital Sky\nSurvey - a large-sized sample containing nearly equal proportion of diverse\nrange of Seyfert galaxies showing similar redshift distributions compiled by\nGelbord et al. (2009) using the Very Large Array survey images. The radio\ndetection rate is low, 49%, which is lower than the detection rate of several\nother known Seyfert galaxy samples. These galaxies show low star formation\nrates and the radio emission is dominated by the active nucleus with $\\le$10%\ncontribution from thermal emission, and possibly, none show evidence for\nrelativistic beaming. The radio detection rate, distributions of radio power,\nand correlations between radio power and line luminosities or X-ray luminosity\nfor narrow-line Seyfert 1 (NLS1), Seyfert 1 and Seyfert 2 galaxies are\nconsistent with the predictions of the unified scheme hypothesis. Using\ncorrelation between radio and [O\\,III]\\,$\\lambda$ \\,5007\\,\\AA\\ luminosities, we\nshow that $\\sim$8% sample sources are radio-intermediate and the remaining are\nradio-quiet. There is possibly an ionization stratification associated with\nclouds on scales of 0.1-1.0 kpc, which have large optical depths at 1.4 GHz,\nand it seems these clouds are responsible for free-free absorption of radio\nemission from the core, hence, leading to low radio detection rate for these\nFHIL-emitting Seyfert galaxies.", "positive": "Modified gravity (MOG) and the cluster Abell 1689 acceleration data: The galaxy cluster system Abell 1689 has been well studied and yields good\nlensing and X-ray gas data. Modified gravity (MOG) is applied to the cluster\nAbell 1689 and the acceleration data is well fitted without assuming dark\nmatter. Newtonian dynamics and Modified Newtonian dynamics (MOND) are shown not\nto fit the acceleration data, while a dark matter model based on the\nNavarro-Frenk-White (NFW) mass profile is shown to fit the acceleration data\nfor the radial range $r > 200$ kpc." }, { "anchor": "Substructures and tidal distortions in the Magellanic stellar periphery: We use a new panoramic imaging survey, conducted with the Dark Energy Camera,\nto map the stellar fringes of the Large and Small Magellanic Clouds to\nextremely low surface brightness V $\\gtrsim$ 32 mag arcsec$^{-2}$. Our results\nstarkly illustrate the closely interacting nature of the LMC-SMC pair. We show\nthat the outer LMC disk is strongly distorted, exhibiting an irregular shape,\nevidence for warping, and significant truncation on the side facing the SMC.\nLarge diffuse stellar substructures are present both to the north and south of\nthe LMC, and in the inter-Cloud region. At least one of these features appears\nco-spatial with the bridge of RR Lyrae stars that connects the Clouds. The SMC\nis highly disturbed -- we confirm the presence of tidal tails, as well as a\nlarge line-of-sight depth on the side closest to the LMC. Young,\nintermediate-age, and ancient stellar populations in the SMC exhibit strikingly\ndifferent spatial distributions. In particular, those with ages $\\sim$ 1.5-4\nGyr exhibit a spheroidal distribution with a centroid offset from that of the\noldest stars by several degrees towards the LMC. We speculate that the\ngravitational influence of the LMC may already have been perturbing the gaseous\ncomponent of the SMC several Gyr ago. With careful modeling, the variety of\nsubstructures and tidal distortions evident in the Magellanic periphery should\ntightly constrain the interaction history of the Clouds.", "positive": "Probing gaseous halos of galaxies with radio jets: Gaseous halos play a key role for understanding inflow, feedback and the\noverall baryon budget in galaxies. Literature models predict transitions of the\nstate of the gaseous halo between cold and hot accretion, winds, fountains and\nhydrostatic halos at certain galaxy masses. Since luminosities of radio AGN are\nsensitive to halo densities, any significant transition would be expected to\nshow up in the radio luminosities of large samples of galaxies. The Low\nFrequency Array (LOFAR) Two Metre Sky Survey (LoTSS) has indeed identified a\ngalaxy stellar mass scale, $10^{11} M_\\odot$ , above which the radio\nluminosities increase disproportionately. Here, we investigate, if radio\nluminosities of galaxies, especially the marked rise at galaxy masses around\n$10^{11} M_\\odot$, can be explained with standard assumptions on jet powers,\nscaling between black hole-mass and galaxy mass and gaseous halos. We developed\nmodels for the radio luminosity of radio AGN in halos under infall, galactic\nwind and hydrostatic conditions based on observational data and theoretical\nconstraints, and compared it to LoTSS data for a large sample of galaxies in\nthe mass rangebetween $10^{8.5} M_\\odot$ and $10^{12} M_\\odot$. Assuming the\nsame characteristic upper limit to jet powers as is known from high galaxy\nmasses to hold at all masses, we find that the maximum radio luminosities for\nthe hydrostatic gas halos fit well with the upper envelope of the distribution\nof the LOFAR data. The marked rise in radio luminosity at $10^{11} M_\\odot$ is\nmatched in our model, and is related to significant change in halo gas density\naround this galaxy mass, which is a consequence of the lower cooling rates at\nhigher virial temperature. Wind and infall models overpredict the radio\nluminosities at small galaxy masses and have no particular steepening of the\nrun of the radio luminosities predicted at any galaxy mass. [...]" }, { "anchor": "The localization of galaxy groups in close proximity to galaxy clusters\n using cosmic web nodes: We investigate the efficacy of using the cosmic web nodes identified by the\nDisPerSE topological filament finder to systematically identify galaxy groups\nin the infall regions around massive clusters. The large random motions and\ninfall velocities of galaxies in the regions around clusters complicate the\ndetection and characterisation of substructures through normal group-finding\nalgorithms. Yet understanding the co-location of galaxies within filaments\nand/or groups is a key part of understanding the role of environment on galaxy\nevolution, particularly in light of next-generation wide-field spectroscopic\nsurveys. Here we use simulated massive clusters from TheThreeHundred\ncollaboration and compare the derived group catalogues, (haloes with\n$\\sigma_{v} > 300 h^{-1}$ km/s) with the critical points from DisPerSE, ran on\nhaloes with more than 100 particles. We find that in 3D, 56\\% of DisPerSE nodes\nare correctly identified as groups (purity) while 68\\% of groups are identified\nas nodes (completeness). The fraction of matches increases with group mass and\nwith distance from the host cluster centre. This rises to a completeness of\n100\\% for the most massive galaxy groups ($M>10^{14}$ M$_{\\odot}$) in 3D, or\n63\\% when considering the projected 2D galaxy distribution. When a perfect\nmatch occurs between a cosmic web node and a galaxy group, the DisPerSE node\ndensity ($\\delta$) serves as an estimate of the group's mass, albeit with\nsignificant scatter. We conclude that the use of a cosmic filament finder shows\npromise as a useful and straightforward observational tool for disentangling\nsubstructure within the infall regions of massive clusters.", "positive": "Gaia and the dynamics of the Galaxy: Gaia is an ambitious ESA space mission which will provide photometric and\nastrometric measurements with the accuracies needed to produce a kinematic\ncensus of almost one billion stars in our Galaxy. These data will revolutionize\nour understanding of the dynamics of the Milky Way, and our knowledge of its\ndetailed gravitational potential and mass distribution, including the putative\ndark matter component and the non-axisymmetric features such as spiral arms.\nThe Gaia mission will help to answer various currently unsettled questions by\nusing kinematic information on both disk and halo stellar populations. Among\nmany others: what does the rotation curve of the outer Galaxy look like? How\nfar from axisymmetry and equilibrium is the Galaxy? What are the respective\nroles of hierarchical formation and secular evolution in shaping the Galaxy and\nits various components? Are the properties of the Galaxy in accordance with\nexpectations from the standard model of cosmology?" }, { "anchor": "Radially anisotropic systems with $r^{-\u03b1}$ forces: equilibrium\n states: We continue the study of collisionless systems governed by additive\n$r^{-\\alpha}$ interparticle forces by focusing on the influence of the force\nexponent $\\alpha$ on radial orbital anisotropy. In this preparatory work we\nconstruct the radially anisotropic Osipkov-Merritt phase-space distribution\nfunctions for self-consistent spherical Hernquist models with $r^{-\\alpha}$\nforces and $1\\leq\\alpha<3$. The resulting systems are isotropic at the center\nand increasingly dominated by radial orbits at radii larger than the anisotropy\nradius $r_a$. For radially anisotropic models we determine the minimum value of\nthe anisotropy radius $r_{ac}$ as a function of $\\alpha$ for phase-space\nconsistency (such that the phase-space distribution function is nowhere\nnegative for $r_a\\geq r_{ac}$). We find that $r_{ac}$ decreases for decreasing\n$\\alpha$, and that the amount of kinetic energy that can be stored in the\nradial direction relative to that stored in the tangential directions for\nmarginally consistent models increases for decreasing $\\alpha$. In particular,\nwe find that isotropic systems are consistent in the explored range of\n$\\alpha$. By means of direct $N$-body simulations we finally verify that the\nisotropic systems are also stable.", "positive": "The relevance of ram pressure stripping for the evolution of blue\n cluster galaxies as seen at optical wavelengths: Ram pressure stripping is one of the most efficient mechanisms able to affect\nthe gas reservoir in cluster galaxies and in the last decades many studies have\ncharacterized the properties of stripped galaxies. A definite census of the\nimportance of this process in local clusters is though still missing. Here we\ncharacterize the fraction of galaxies showing signs of stripping at optical\nwavelengths, using the data of 66 clusters from the WINGS and OMEGAWINGS\nsurveys. We focus on the infalling galaxy population and hence only consider\nblue, bright (B<18.2) late-type spectroscopically confirmed cluster members\nwithin 2 virial radii. In addition to \"traditional\" stripping candidates (SC)\n-- i.e. galaxies showing unilateral debris and tails -- we also consider\nunwinding galaxies (UG) as potentially stripped galaxies. Recent work has\nindeed unveiled a connection between unwinding features and ram pressure\nstripping and even though only integral field studies can inform on how often\nthese features are indeed due to ram pressure, it is important to include them\nin the global census. We performed a visual inspection of B-band images and\nhere we release a catalog of 143 UG. SC and UG each represent ~15-20% of the\ninspected sample. If we make the assumption that they both are undergoing ram\npressure stripping, we can conclude that at any given time in the low-z\nuniverse about 35% of the infalling cluster population show signs of stripping\nin their morphology at optical wavelengths. These fractions depend on color,\nmass, morphology, and little on clustercentric distance. Making some rough\nassumptions on the duration of the tail visibility and on the time cluster\ngalaxies can maintain blue colors, we infer that almost all bright blue\nlate-type cluster galaxies undergo a stripping phase during their life,\nboosting the importance of ram pressure stripping in cluster galaxy evolution." }, { "anchor": "Evidence of interacting elongated filaments in the star-forming site\n AFGL 5142: To probe the ongoing physical mechanism, we studied a wide-scale environment\naround AFGL 5142 (area ~25 pc x 20 pc) using a multi-wavelength approach. The\nHerschel column density (N(H_2)) map reveals a massive inverted Y-like\nstructure (mass ~6280 M_sun), which hosts a pair of elongated filaments\n(lengths >10 pc). The Herschel temperature map depicts the filaments in a\ntemperature range of ~12.5-13.5 K. These elongated filaments overlap each other\nat several places, where N(H_2) > 4.5 x 10^{21}cm^{-2}. The 12CO and 13CO line\ndata also show two elongated cloud components (around -1.5 and -4.5 km/s)\ntoward the inverted Y-like structure, which are connected in the velocity\nspace. First moment maps of CO confirm the presence of two intertwined\nfilamentary clouds along the line of sight. These results explain the\nmorphology of the inverted Y-like structure through a combination of two\ndifferent filamentary clouds, which are also supported by the distribution of\nthe cold HI gas. Based on the distribution of young stellar objects (YSOs),\nstar formation (SF) activities are investigated toward the inverted Y-like\nstructure. The northern end of the structure hosts AFGL 5142 and tracers of\nmassive SF, where high surface density of YSOs (i.e., 5-240 YSOs/pc^2) reveals\nstrong SF activity. Furthermore, noticeable YSOs are found toward the\noverlapping zones of the clouds. All these observational evidences support a\nscenario of collision/interaction of two elongated filamentary clouds/flows,\nwhich appears to explain SF history in the site AFGL 5142.", "positive": "A Deeper Look at the New Milky Way Satellites: Sagittarius II, Reticulum\n II, Phoenix II, and Tucana III: We present deep Magellan/Megacam stellar photometry of four recently\ndiscovered faint Milky Way satellites: Sagittarius II (Sgr II), Reticulum II\n(Ret II), Phoenix II (Phe II), and Tucana III (Tuc III). Our photometry reaches\n~2-3 magnitudes deeper than the discovery data, allowing us to revisit the\nproperties of these new objects (e.g., distance, structural properties,\nluminosity measurements, and signs of tidal disturbance). The satellite\ncolor-magnitude diagrams show that they are all old (~13.5 Gyr) and metal-poor\n([Fe/H]$\\lesssim-2.2$). Sgr II is particularly interesting as it sits in an\nintermediate position between the loci of dwarf galaxies and globular clusters\nin the size-luminosity plane. The ensemble of its structural parameters is more\nconsistent with a globular cluster classification, indicating that Sgr II is\nthe most extended globular cluster in its luminosity range. The other three\nsatellites land directly on the locus defined by Milky Way ultra-faint dwarf\ngalaxies of similar luminosity. Ret II is the most elongated nearby dwarf\ngalaxy currently known for its luminosity range. Our structural parameters for\nPhe II and Tuc III suggest that they are both dwarf galaxies. Tuc III is known\nto be associated with a stellar stream, which is clearly visible in our\nmatched-filter stellar density map. The other satellites do not show any clear\nevidence of tidal stripping in the form of extensions or distortions. Finally,\nwe also use archival HI data to place limits on the gas content of each object." }, { "anchor": "Optical and JWST Mid-IR Emission Line Diagnostics for Simultaneous IMBH\n and Stellar Excitation in z~0 Dwarf Galaxies: Current observational facilities have yet to conclusively detect $10^3 - 10^4\nM_{\\odot}$ intermediate mass black holes (IMBHs) that fill in the evolutionary\ngap between early universe seed black holes and $z \\sim 0$ supermassive black\nholes. Dwarf galaxies present an opportunity to reveal active IMBHs amidst\npersistent star formation. We introduce photoionization simulations tailored to\naddress key physical uncertainties: coincident vs. non-coincident mixing of\nIMBH and starlight excitation, open vs. closed surrounding gas cloud\ngeometries, and different AGN SED shapes. We examine possible AGN emission line\ndiagnostics in the optical and mid-IR, and find that the diagnostics are often\ndegenerate with respect to the investigated physical uncertainties. In spite of\nthese setbacks, and in contrast to recent work, we are able to show that [O\nIII]/H$\\beta$ typically remains bright for dwarf AGN powered by IMBHs down to\n$10^3 M_{\\odot}$. Dwarf AGN are predicted to have inconsistent star-forming and\nSeyfert/LINER classifications using the most common optical diagnostics. In the\nmid-IR, [O IV] 25.9$\\mu$m and [Ar II] 6.98$\\mu$m are less sensitive to physical\nuncertainties than are optical diagnostics. Based on these emission lines, we\nprovide several mid-IR emission line diagnostic diagrams with demarcations for\nseparating starbursts and AGN with varying levels of activity. The diagrams are\nvalid over a wide range of ionization parameters and metallicities out to\n$z\\sim0.1$, so will prove useful for future JWST observations of local dwarf\nAGN in the search for IMBHs. We make our photoionization simulation suite\nfreely available.", "positive": "Stacking Analysis of 12CO and 13CO Spectra of NGC3627: Existence of\n non-optically thick 12CO emission?: We stacked 12CO and 13CO spectra of NGC 3627 after redefining the velocity\naxis of each spectrum of the mapping data so that the zero corresponds to the\nlocal mean velocity of 12CO spectra. The signal-to-noise ratios of the\nresulting spectra are improved by a factor of up to 3.2 compared to those\nobtained with normal stacking analysis. We successfully detect a weak 13CO\nemission from the interarm region where the emission was not detected in the\nindividual pointings. We compare the integrated intensity ratios I12 CO/I13 CO\namong six characteristic regions (center, bar, bar-end, offset, arm, and\ninterarm). We find that I12CO/I13CO in the bar and interarm are higher than\nthose in the other regions by a factor of ~2 and I12CO/I13CO in the center is\nmoderately high. These high I12CO/I13CO ratios in the bar and center are\nattributed to a high intensity ratio (T12CO/T13CO) and one in the interarm is\nattributed to a high ratio of the full width at half maximum of spectra\n(FWHM12CO/FWHM13CO). The difference between FWHM12CO and FWHM13CO of the\ninterarm indicates the existence of two components, one with a narrow line\nwidth (~FWHM13CO) and the other with a broad line width (~FWHM12CO).\nAdditionally, the T12CO/T13CO ratio in the broad-line-width component of the\ninterarm is higher than the other regions. The high T12CO/T13CO in the center\nand bar and of the broad-line-width component in the interarm suggest the\nexistence of non-optically thick 12CO components. We find that more than half\nof the 12CO emissions of the interarm are likely to be radiated from the\ndiffuse component. Our result suggests that the use of a universal CO-to-H2\nconversion factor might lead to an overestimation of molecular gas mass and\nunderestimation of star-formation efficiency in the interarm by a factor of a\nfew." }, { "anchor": "Sub-damped Lyman alpha systems in the XQ-100 survey II -- Chemical\n evolution at 2.4 5$ compared to earlier results that\ndid not use the MIRI photometry. Within the standard $\\Lambda$CDM cosmology,\nour results require a moderate increase in the baryon-to-star conversion\nefficiency ($\\epsilon$) towards higher redshifts and higher $M_{\\star}$. For\nthe most massive galaxies at $z\\sim 8$, the required $\\epsilon$ is $\\sim 0.3$,\nin comparison to $\\epsilon \\sim 0.14$ for typical low-redshift galaxies. Our\nfindings are consistent with models assuming suppressed stellar feedback due to\nthe high gas density and the associated short free-fall time expected for\nmassive halos at high redshift.", "positive": "Planck Early Results: The Galactic Cold Core Population revealed by the\n first all-sky survey: We present the statistical properties of the first version of the Cold Core\nCatalogue of Planck Objects (C3PO), in terms of their spatial distribution,\ntemperature, distance, mass, and morphology. We also describe the statistics of\nthe Early Cold Core Catalogue (ECC, delivered with the Early Release Compact\nSource Catalogue, ERCSC) that is the subset of the 915 most reliable detections\nof the complete catalogue. We have used the CoCoCoDeT algorithm to extract\n10783 cold sources. Temperature and dust emission spectral index {\\beta} values\nare derived using the fluxes in the IRAS 100 \\mum band and the three highest\nfrequency Planck bands. Temperature spans from 7K to 17K, and peaks around 13K.\nData are not consistent with a constant value of {\\beta} over the all\ntemperature range. {\\beta} ranges from 1.4 to 2.8 with a mean value around 2.1,\nand several possible scenarios are possible, including {\\beta}(T) and the\neffect of multiple T components folded into the measurements. For one third of\nthe objects the distances are obtained. Most of the detections are within 2 kpc\nin the Solar neighbourhood, but a few are at distances greater than 4 kpc. The\ncores are distributed from the deep Galactic plane, despite the confusion, to\nhigh latitudes (>30$^{\\circle}$). The associated mass estimates range from 1 to\n$10^5$ solar masses. Using their physical properties these cold sources are\nshown to be cold clumps, defined as the intermediate cold sub-structures\nbetween clouds and cores. These cold clumps are not isolated but mostly\norganized in filaments associated with molecular clouds. The Cold Core\nCatalogue of Planck Objects (C3PO) is the first unbiased all-sky catalogue of\ncold objects. It gives an unprecedented statistical view to the properties of\nthese potential pre-stellar clumps and offers a unique possibility for their\nclassification in terms of their intrinsic properties and environment." }, { "anchor": "Non-thermal emission from massive star forming regions: A possible SNR\n candidate G351.7-1.2?: We present low frequency wide band observations (300-500 MHz) of the star\nforming complex G351.7-1.2 using upgraded Giant Metrewave Radio Telescope\n(uGMRT), India. Combining this with the optical, infrared and submillimeter\ndata, we analyse the large scale diffuse radio emission associated with the\nregion that exhibits a broken shell morphology. The spectral index of the\nemission in the shell is -0.8, indicating non-thermal emission. H-alpha\nemission that mimics the morphology of the radio shell on a smaller scale is\nalso detected here. Based on the non-thermal emission from the radio shell and\nthe presence of its optical counterpart, we classify G351.7-1.2 as a candidate\nSNR. A gamma-ray source detected by Fermi LAT (1FGLJ1729.1-3641c) is located\ntowards the south-west of the radio shell and could have a possible origin in\nthe interaction between high velocity particles from the SNR and the ambient\nmolecular cloud.", "positive": "A Parameter Space Exploration of High Resolution Numerically Evolved\n Early Type Galaxies Including AGN Feedback and Accurate Dynamical Treatment\n of Stellar Orbits: An extensive exploration of the model parameter space of axisymmetric\nEarly-Type Galaxies (ETGs) hosting a central supermassive Black Hole (SMBH) is\nconducted by means of high resolution hydrodynamical simulations performed with\nour code MACER. Global properties such as 1) total SMBH accreted mass, 2) final\nX-ray luminosity and temperature of the X-ray emitting halos, 3) total amount\nof new stars formed from the cooling gas, 4) total ejected mass in form of\nsupernovae and AGN feedback induced galactic winds, are obtained as a function\nof galaxy structure and internal dynamics. In addition to the galactic dark\nmatter halo, the model galaxies are also embedded in a group/cluster dark\nmatter halo; finally cosmological accretion is also included, with amount and\ntime dependence derived from cosmological simulations. Angular momentum\nconservation leads to the formation of cold HI disks; these disks further\nevolve under the action of star formation induced by disk instabilities, of the\nassociated mass discharge onto the central SMBH, and of the consequent AGN\nfeedback. At the end of the simulations, the hot (metal enriched) gas mass is\nroughly $10\\%$ the mass in the old stars, with twice as much having been\nejected into the intergalactic medium. The cold gas disks are a $\\approx$ kpc\nin size, and the metal rich new stars are in $0.1$ kpc disks. The masses of\ncold gas and new stars are roughly $0.1\\%$ the mass of the old stars. Overall,\nthe final systems appear to reproduce quite successfully the main global\nproperties of real ETGs." }, { "anchor": "On the possibility of laboratory simulation of quasi-spherical accretion\n onto black holes with a shallow-water experimental setup: We describe the concept of a shallow-water setup for simulation of gas\naccretion onto a black hole in the mode of a quasi-spherical accretion. The\nbottom for the shallow-water container must have the funnel-shaped curvilinear\nconcavo-convex shape. We calculate the configuration surface of the properly\nshaped bottom that simulates precisely the Newtonian or pseudo-Newtonian\ngravitational potentials. Like the spatial part of the Schwarzchild metric, the\nfunnel's surface metric has a (removable) singularity at the finite distance\nfrom the funnel's center and places the certain funnel's depth which we call\n`gravitational length'. The gravitational length is analogous to the\ngravitational radius and defines the equivalent of the black hole's mass in the\nlaboratory model. The mass equivalent corresponds to $\\sim 0.367\\cdot 10^{12}$\ng for the funnel as deep as 5 cm. We define more precisely the inviscid shallow\nwater equations for the arbitrary bottom curvature. We show that in general\ncase the shallow water pressure obeys the non-barotropic equation of state. We\nsuggest the schematic course for experiments for simulation of accretion in a\nthick accretion disk mode as well as the Bondi-Hoyle accretion.", "positive": "Streams, substructures and the early history of the Milky Way: The advent of Gaia's 2nd data release in combination with large spectroscopic\nsurveys are revolutionizing our understanding of the Galaxy. Thanks to these\nand the knowledge accumulated thus far, a more mature picture of the evolution\nof the early Milky Way is emerging:\n * Two of the traditional Galactic components, i.e. the stellar halo and the\nthick disk, appear to be intimately linked: stars with halo-like kinematics\noriginate in similar proportions, from a \"heated\" (thick) disk and from debris\nfrom a system named Gaia-Enceladus. Gaia-Enceladus was the last big merger\nevent experienced by the Milky Way and probably completed around 10 Gyr ago.\nThe puffed-up stars now present in the halo as a consequence of the merger have\nthus exposed the existence of a disk component at z ~ 1.8.\n * The Helmi streams, Sequoia, and Thamnos are amongst the newly uncovered or\nbetter characterized merger events. Knowledge of their progenitor's properties,\nstar formation and chemical histories is still incomplete.\n * Debris' from different objects often overlap in phase-space. A task for the\nnext years will be to use spectroscopic surveys for chemical labelling and to\ndisentangle events from one another using dimensions other than only\nphase-space, metallicity or [alpha/Fe].\n * These surveys will also provide line-of-sight velocities missing for faint\nstars and more accurate distance determinations for distant objects. The\nresulting samples of stars will cover a much wider volume of the Galaxy\nallowing, for example, linking kinematic substructures in the inner halo to\nspatial overdensities in the outer halo.\n * All the results obtained so far are in-line with expectations of current\ncosmological models. Yet, tailored hydrodynamical simulations as well as\n\"constrained\" cosmological simulations are needed to push our knowledge of the\nassembly of the Milky Way back to the earliest times. [abridged]" }, { "anchor": "A simple and general method for solving detailed chemical evolution with\n delayed production of iron and other chemical elements: We present a theoretical method for solving the chemical evolution of\ngalaxies, by assuming an instantaneous recycling approximation for chemical\nelements restored by massive stars and the Delay Time Distribution formalism\nfor the delayed chemical enrichment by Type Ia Supernovae. The galaxy gas mass\nassembly history, together with the assumed stellar yields and initial mass\nfunction, represent the starting point of this method. We derive a simple and\ngeneral equation which closely relates the Laplace transforms of the galaxy gas\naccretion history and star formation history, which can be used to simplify the\nproblem of retrieving these quantities in the galaxy evolution models assuming\na linear Schmidt-Kennicutt law. We find that - once the galaxy star formation\nhistory has been reconstructed from our assumptions - the differential equation\nfor the evolution of the chemical element $X$ can be suitably solved with\nclassical methods. We apply our model to reproduce the [O/Fe] and [Si/Fe] vs.\n[Fe/H] chemical abundance patterns as observed at the solar neighborhood, by\nassuming a decaying exponential infall rate of gas and different delay time\ndistributions for Type Ia Supernovae; we also explore the effect of assuming a\nnonlinear Schmidt-Kennicutt law, with the index of the power law being $k=1.4$.\nAlthough approximate, we conclude that our model with the single degenerate\nscenario for Type Ia Supernovae provides the best agreement with the observed\nset of data. Our method can be used by other complementary galaxy stellar\npopulation synthesis models to predict also the chemical evolution of galaxies.", "positive": "Near-UV Sources in the Hubble Ultra Deep Field: The Catalog: The catalog from the first high resolution U-band image of the Hubble Ultra\nDeep Field, taken with Hubble's Wide Field Planetary Camera 2 through the F300W\nfilter, is presented. We detect 96 U-band objects and compare and combine this\ncatalog with a Great Observatories Origins Deep Survey (GOODS) B-selected\ncatalog that provides B, V, i, and z photometry, spectral types, and\nphotometric redshifts. We have also obtained Far-Ultraviolet (FUV, 1614 \\AA)\ndata with Hubble's Advanced Camera for Surveys Solar Blind Channel (ACS/SBC)\nand with Galaxy Evolution Explorer (GALEX). We detected 31 sources with\nACS/SBC, 28 with GALEX/FUV, and 45 with GALEX/NUV. The methods of observations,\nimage processing, object identification, catalog preparation, and catalog\nmatching are presented." }, { "anchor": "Dust and gas in the central region of NGC 1316 (Fornax A) -- Its origin\n and nature: The early-type galaxy NGC 1316 hosts about 10^7 solar masses of dust within a\ncentral radius of 5 kpc. These prominent dust structures are believed to have\nan external origin, which is also a popular interpretation for other dusty\nearly-type galaxies. We use archival Hubble Space Telescope/ACS data to\nconstruct colour maps that delineate the dust pattern in detail, and we compare\nthese data with maps constructed with data from MUSE of the VLT at the European\nSouthern Observatory. Twelve MUSE pointings in wide field mode form a mosaic of\nthe central 3.3'x2.4'. We use the tool PyParadise to fit the stellar\npopulation. We use the residual emission lines and the residual interstellar\nabsorption NaI D-lines, and we measure line strengths, the velocity field, and\nthe velocity dispersion field. The emission lines resemble LINER lines, with\n[NII] being the strongest line everywhere. Ionising sources are plausibly the\npost-asymptotic giant branch stars of the old or intermediate-age stellar\npopulation. There is a striking match between the dust structures, ionised gas,\nand atomic gas distributions, the last of which is manifested by interstellar\nabsorption residuals of the stellar NaI D-lines. In the dust-free regions, the\ninterstellar NaI D-lines appear in emission, which is indicative of a galactic\nwind. The velocity field of the ionised gas (and thus of the dust) is\ncharacterised by small-scale turbulent movements that indicate short lifetimes.\nAt the very centre, a bipolar velocity field of the ionised gas is observed,\nwhich we interpret as an outflow. We identify a strongly inclined gaseous dusty\ndisc along the major axis of NGC1316. A straight beam of ionised gas with a\nlength of about 4 kpc emanates from the centre. Our findings are strongly\nsuggestive of a dusty outflow. Nuclear outflows may be important dust-producing\nmachines in galaxies. (Abridged)", "positive": "The role of ices in star-forming clouds: Ices play a critical role during the evolution of interstellar clouds. Their\npresence is ubiquitous in the dense molecular medium and their impact is not\nonly limited to chemistry. Species adsorbed onto dust grains also affect cloud\nthermodynamics. It all depends on the interstellar conditions, the chemical\nparameters, and the composition of ice layers. In this work, I study the\nformation of ices by focusing on the interplay between gas and solid phase to\ndetermine their role on cloud evolution and star formation. I show that while\nthe formation of ices greatly impacts the cloud chemistry, their role on the\nthermodynamics is more conservative, and their influence on star formation is\nonly marginal." }, { "anchor": "A Uniformly Selected, All-Sky, Optical AGN Catalog: We have constructed an all-sky catalog of optical AGNs with $z < 0.09$, based\non optical spectroscopy, from the parent sample of galaxies in the 2MASS\nRedshift Survey (2MRS), a near-complete census of the nearby universe. Our\ncatalog consists of 1929 broad line AGNs, and 6562 narrow line AGNs which\nsatisfy the \\citet{Kauffmann03} criteria, of which 3607 also satisfy the\n\\citet{Kewley01} criteria. We also report emission line widths, fluxes, flux\nerrors, and signal-to-noise ratios of all the galaxies in our spectroscopic\nsample, allowing users to customize the selection criteria. Although we\nuniformly processed the spectra of galaxies from a homogeneous parent sample,\ninhomogeneities persist due to the differences in the quality of the obtained\nspectra, taken with different instruments, and the unavailability of spectra\nfor $\\sim$20\\% of the galaxies. We quantify how the differences in spectral\nquality affect not only the AGN detection rates but also broad line to narrow\nline AGN ratios. We find that the inhomogeneities primarily stem from the\ncontinuum signal-to-noise (S/N) in the spectra near the emission lines of\ninterest. We fit for the AGN fraction as a function of continuum S/N and assign\nAGN likelihoods to galaxies which were not identified as AGNs using the\navailable spectra. This correction results in a catalog suitable for\nstatistical studies. This work also paves the way for a truly homogeneous and\ncomplete nearby AGN catalog by identifying galaxies whose AGN status needs to\nbe verified with higher quality spectra, quantifying the spectral quality\nnecessary to do so.", "positive": "The influence of continuum radiation fields on hydrogen radio\n recombination lines: Calculations of hydrogen departure coefficients using a model with the\nangular momentum quantum levels resolved that includes the effects of external\nradiation fields are presented. The stimulating processes are important at\nradio frequencies and can influence level populations. New numerical techniques\nwith a solid mathematical basis have been incorporated into the model to ensure\nconvergence of the solution. Our results differ from previous results by up to\n20 per cent. A direct solver with a similar accuracy but more efficient than\nthe iterative method is used to evaluate the influence of continuum radiation\non the hydrogen population structure. The effects on departure coefficients of\ncontinuum radiation from dust, the cosmic microwave background, the stellar\nionising radiation, and free-free radiation are quantified. Tables of emission\nand absorption coefficients for interpreting observed radio recombination lines\nare provided." }, { "anchor": "Formation of the Andromeda Giant Stream: Asymmetric Structure and Disc\n Progenitor: We focus on the evidence of a past minor merger discovered in the halo of the\nAndromeda galaxy (M31). Previous N-body studies have enjoyed moderate success\nin producing the observed giant stellar stream (GSS) and stellar shells in\nM31's halo. The observed distribution of stars in the halo of M31 shows an\nasymmetric surface brightness profile across the GSS; however, the effect of\nthe morphology of the progenitor galaxy on the internal structure of the GSS\nrequires further investigation in theoretical studies. To investigate the\nphysical connection between the characteristic surface brightness in the GSS\nand the morphology of the progenitor dwarf galaxy, we systematically vary the\nthickness, rotation velocity and initial inclination of the disc dwarf galaxy\nin N-body simulations. The formation of the observed structures appears to be\ndominated by the progenitor's rotation. Besides reproducing the observed GSS\nand two shells in detail, we predict additional structures for further\nobservations. We predict the detectability of the progenitor's stellar core in\nthe phase-space density distribution, azimuthal metallicity gradient of the\nwestern shell-like structure and an additional extended shell in the\nnorth-western direction that may constrain the properties of the progenitor\ngalaxy.", "positive": "VVV WIN 1733$-$3349: a low extinction window to probe the far side of\n the Milky Way bulge: Windows of low extinction in the Milky Way (MW) have been used along the past\ndecades for the study of the Galactic structure and the stellar population\nacross the inner bulge and disk. Here we report the analysis of another low\nextinction near-IR window discovered by the VISTA Variables in the V\\'ia\nL\\'actea Survey. VVV WIN 1733$-$3349 is about half a degree in size and is\nconveniently located right in the MW plane, at Galactic coordinates $(l, b) =\n(-5.2, -0.3)$. The mean extinction of VVV WIN 1733$-$3349 is $A_{Ks} =\n0.61\\pm0.08$ mag, which is much smaller than the extinction in the surrounding\narea. The excess in the star counts is consistent with the reduced extinction,\nand complemented by studying the distribution of red clump (RC) stars. Thanks\nto the strategic low-latitude location of VVV WIN 1733$-$3349, we are able to\ninterpret their RC density fluctuations with the expected overdensities due to\nthe presence of the spiral arms beyond the bulge. In addition, we find a clear\nexcess in the number of microlensing events within the window, which\ncorroborates our interpretation that VVV WIN 1733$-$3349 is revealing the far\nside of the MW bulge." }, { "anchor": "High-Resolution Radiative Transfer Modelling of M33: In this work, we characterise the contributions from both ongoing star\nformation and the ambient radiation field in Local Group galaxy M33, as well as\nestimate the scale of the local dust-energy balance (i.e. the scale at which\nthe dust is re-emitting starlight generated in that same region) in this galaxy\nthrough high-resolution radiative transfer (RT) modelling, with defined stellar\nand dust geometries. We have characterised the spectral energy distribution\n(SED) of M33 from UV to sub-mm wavelengths, at a spatial scale of 100 pc. We\nconstructed input maps of the various stellar and dust geometries for use in\nthe RT modelling. By modifying our dust mix (fewer very small carbon grains and\na lower silicate-to-carbon ratio as compared to the Milky Way), we can much\nbetter fit the sub-mm dust continuum. Using this new dust composition, we find\nthat we are able to well reproduce the observed SED of M33 using our adopted\nmodel. In terms of stellar attenuation by dust, we find a reasonably strong,\nbroad UV bump, as well as significant systematic differences in the amount of\ndust attenuation when compared to standard SED modelling. We also find\ndiscrepancies in the residuals of the spiral arms versus the diffuse\ninterstellar medium (ISM), indicating a difference in properties between these\ntwo regimes. The dust emission is dominated by heating due to the young stellar\npopulations at all wavelengths ($\\sim$80% at 10 $\\mu$m to $\\sim$50% at 1 mm).\nWe find that the local dust-energy balance is restored at spatial scales\ngreater than around 1.5 kpc.", "positive": "Dark Matter in Ultra-Diffuse Galaxies in the Virgo Cluster from their\n Globular Cluster Populations: We present Keck/DEIMOS spectroscopy of globular clusters (GCs) around the\nultra-diffuse galaxies (UDGs) VLSB-B, VLSB-D, and VCC615 located in the central\nregions of the Virgo cluster. We spectroscopically identify 4, 12, and 7 GC\nsatellites of these UDGs, respectively. We find that the three UDGs have\nsystemic velocities ($V_{sys}$) consistent with being in the Virgo cluster, and\nthat they span a wide range of velocity dispersions, from $\\sim 16$ to $\\sim\n47$ km/s, and high dynamical mass-to-light ratios within the radius that\ncontains half the number of GCs ($ 407^{+916}_{-407}$, $21^{+15}_{-11}$,\n$60^{+65}_{-38}$, respectively). VLSB-D shows possible evidence for rotation\nalong the stellar major axis and its $V_{sys}$ is consistent with that of the\nmassive galaxy M84 and the center of the Virgo cluster itself. These findings,\nin addition to having a dynamically and spatially ($\\sim 1$ kpc) off-centered\nnucleus and being extremely elongated, suggest that VLSB-D could be tidally\nperturbed. On the contrary, VLSB-B and VCC615 show no signals of tidal\ndeformation. Whereas the dynamics of VLSB-D suggest that it has a less massive\ndark matter halo than expected for its stellar mass, VLSB-B and VCC615 are\nconsistent with a $\\sim 10^{12}$ M$_{\\odot}$ dark matter halo. Although our\nsamples of galaxies and GCs are small, these results suggest that UDGs may be a\ndiverse population, with their low surface brightnesses being the result of\nvery early formation, tidal disruption, or a combination of the two." }, { "anchor": "Probing The Ultraviolet Luminosity Function of the Earliest Galaxies\n with the Renaissance Simulations: In this paper, we present the first results from the Renaissance Simulations,\na suite of extremely high-resolution and physics-rich AMR calculations of high\nredshift galaxy formation performed on the Blue Waters supercomputer. These\nsimulations contain hundreds of well-resolved galaxies at $z \\sim 25-8$, and\nmake several novel, testable predictions. Most critically, we show that the\nultraviolet luminosity function of our simulated galaxies is consistent with\nobservations of high-z galaxy populations at the bright end of the luminosity\nfunction (M$_{1600} \\leq -17$), but at lower luminosities is essentially flat\nrather than rising steeply, as has been inferred by Schechter function fits to\nhigh-z observations, and has a clearly-defined lower limit in UV luminosity.\nThis behavior of the luminosity function is due to two factors: (i) the strong\ndependence of the star formation rate on halo virial mass in our simulated\ngalaxy population, with lower-mass halos having systematically lower star\nformation rates and thus lower UV luminosities; and (ii) the fact that halos\nwith virial masses below $\\simeq 2 \\times 10^8$ M$_\\odot$ do not universally\ncontain stars, with the fraction of halos containing stars dropping to zero at\n$\\simeq 7 \\times 10^6$ M$_\\odot$. Finally, we show that the brightest of our\nsimulated galaxies may be visible to current and future ultra-deep space-based\nsurveys, particularly if lensed regions are chosen for observation.", "positive": "Nebular dominated galaxies in the early Universe with top-heavy stellar\n initial mass functions: The stellar initial mass function (IMF) impacts nearly all observable\nproperties of galaxies, controls the production rate of heavy elements, and\ngoverns how much energy is available to regulate galaxy growth. Theoretical\nwork predicts that the high-redshift IMF may be more top-heavy compared to the\nlocal Universe, due to higher gas pressures, a higher Cosmic Microwave\nBackground temperature, and lower metallicities. However, direct observational\nevidence for a top-heavy IMF at high-redshift remains elusive. Here we report\nthe detection of two Lyman-$\\alpha$-emitting galaxies at redshift $5.9$ and\n$7.9$ that show evidence for exceptionally top-heavy IMFs. Our analysis of\nJWST/NIRSpec data demonstrates that these galaxies exhibit spectra which are\ncompletely dominated by the nebular continuum. Alongside a clear Balmer jump,\nwe observe a steep turnover in the ultraviolet continuum. Although this feature\ncan be produced by an extremely thick damped Lyman-$\\alpha$ system with holes,\nwe show instead that this turnover is two-photon emission from neutral\nhydrogen. Two-photon emission can only dominate if the ionizing emissivity is\n$\\gtrsim10\\times$ that of a typical star-forming galaxy. While weak He~{\\sc~II}\nemission disfavours ionizing contributions from AGN or X-ray binaries, such\nradiation fields can be produced in star clusters dominated by low-metallicity\nstars of $\\gtrsim50\\ {\\rm M_{\\odot}}$, where the IMF is $10-30\\times$ more\ntop-heavy than typically assumed. Such a top-heavy IMF implies our\nunderstanding of star formation in the early Universe and the sources of\nreionization may need revision." }, { "anchor": "Extreme Variability in a Broad Absorption Line Quasar: CRTS J084133.15+200525.8 is an optically bright quasar at z=2.345 that has\nshown extreme spectral variability over the past decade. Photometrically, the\nsource had a visual magnitude of V~17.3 between 2002 and 2008. Then, over the\nfollowing five years, the source slowly brightened by approximately one\nmagnitude, to V~16.2. Only ~1 in 10,000 quasars show such extreme variability,\nas quantified by the extreme parameters derived for this quasar assuming a\ndamped random walk model. A combination of archival and newly acquired spectra\nreveal the source to be an iron low-ionization broad absorption line (FeLoBAL)\nquasar with extreme changes in its absorption spectrum. Some absorption\nfeatures completely disappear over the 9 years of optical spectra, while other\nfeatures remain essentially unchanged. We report the first definitive redshift\nfor this source, based on the detection of broad H-alpha in a Keck/MOSFIRE\nspectrum. Absorption systems separated by several 1000 km/s in velocity show\ncoordinated weakening in the depths of their troughs as the continuum flux\nincreases. We interpret the broad absorption line variability to be due to\nchanges in photoionization, rather than due to motion of material along our\nline of sight. This source highlights one sort of rare transition object that\nastronomy will now be finding through dedicated time-domain surveys.", "positive": "sMILES SSPs: A Library of Semi-Empirical MILES Stellar Population Models\n with Variable [$\u03b1$/Fe] Abundances: We present a new library of semi-empirical stellar population models that are\nbased on the empirical MILES and semi-empirical sMILES stellar libraries. The\nmodels span a large range of age and metallicity, in addition to an\n[$\\alpha$/Fe] coverage from $-$0.2 to $+$0.6 dex, at MILES resolution\n(FWHM=2.5$ \\mathring {\\mathrm A}$) and wavelength coverage (3540.5-7409.6$\n\\mathring {\\mathrm A}$). These models are aimed at exploring abundance ratios\nin the integrated light from stellar populations in star clusters and galaxies.\nOur approach is to build SSPs from semi-empirical stars at particular\n[$\\alpha$/Fe] values, thus producing new SSPs at a range of [$\\alpha$/Fe]\nvalues from sub-solar to super-solar. We compare these new SSPs with previously\npublished and well-used models and find similar abundance pattern predictions,\nbut with some differences in age indicators. We illustrate a potential\napplication of our new SSPs, by fitting them to the high signal-to-noise data\nof stacked SDSS galaxy spectra. Age, metallicity and [$\\alpha$/Fe] trends were\nmeasured for galaxy stacks with different stellar velocity dispersions and show\nsystematic changes, in agreement with previous analyses of subsets of those\ndata. These new SSPs are made publicly available." }, { "anchor": "A new gas cooling model for semi-analytical galaxy formation models: Semi-analytic galaxy formation models are widely used to gain insight into\nthe astrophysics of galaxy formation and in model testing, parameter space\nsearching and mock catalogue building. In this work we present a new model for\ngas cooling in halos in semi-analytic models, which improves over previous\ncooling models in several ways. Our new treatment explicitly includes the\nevolution of the density profile of the hot gas driven by the growth of the\ndark matter halo and by the dynamical adjustment of the gaseous corona as gas\ncools down. The effect of the past cooling history on the current mass cooling\nrate is calculated more accurately, by doing an integral over the past history.\nThe evolution of the hot gas angular momentum profile is explicitly followed,\nleading to a self-consistent and more detailed calculation of the angular\nmomentum of the cooled down gas. This model predicts higher cooled down masses\nthan the cooling models previously used in GALFORM, closer to the predictions\nof the cooling models in L-GALAXIES and MORGANA, even though those models are\nformulated differently. It also predicts cooled down angular momenta that are\nhigher than in previous GALFORM cooling models, but generally lower than the\npredictions of L-GALAXIES and MORGANA. When used in a full galaxy formation\nmodel, this cooling model improves the predictions for early-type galaxy sizes\nin GALFORM.", "positive": "A Cold and Diffuse Giant Molecular Filament in the Region of\n $l=41^\\circ$, $b=-1^\\circ$: Data of $^{12}$CO/$^{13}$CO/C$^{18}$O $J=1\\to0$ emission toward the Galactic\nplane region of $l=35^\\circ$ to $45^\\circ$ and $b= -5^\\circ$ to $+5^\\circ$ are\navailable with the Milky Way Imaging Scroll Painting (MWISP) project. Using the\ndata, we found a giant molecular filament (GMF) around\n$l\\approx38\\sim42^\\circ$, $b\\approx-3.5\\sim0^\\circ$, $V_{LSR} \\approx 27 \\sim\n40$ km~s$^{-1}$, named the GMF MWISP G041-01. At a distance of 1.7 kpc, the GMF\nis about 160 pc long. With a median excitation temperature about 7.5 K and a\nmedian column density about $10^{21}$ cm$^{-2}$, this GMF is very cold and very\ndiffuse compared to known GMFs. Using the morphology in the data cube, the GMF\nis divided into four components among which three show filamentary structure.\nMasses of the components are $ 10^3 \\sim 10^4 M_\\odot$, with a total mass for\nthe whole filament being about $7\\times10^4 M_\\odot$ from the LTE method.\n$^{13}$CO cores inside each component are searched. Virial parameters are about\n2.5 for these cores and have a power-law index of -0.34 against the mass. The\nmass fraction of dense cores traced by $^{13}$CO to the diffuse clouds traced\nby $^{12}$CO are about 7% for all components of the GMF. We found signatures of\npossible large scale filament-filament collision in the GMF." }, { "anchor": "Investigating the Unification of LOFAR-detected powerful AGN in the\n Bo\u00f6tes Field: Low radio frequency surveys are important for testing unified models of\nradio-loud quasars and radio galaxies. Intrinsically similar sources that are\nrandomly oriented on the sky will have different projected linear sizes.\nMeasuring the projected linear sizes of these sources provides an indication of\ntheir orientation. Steep-spectrum isotropic radio emission allows for\norientation-free sample selection at low radio frequencies. We use a new radio\nsurvey of the Bo\\\"otes field at 150 MHz made with the Low Frequency Array\n(LOFAR) to select a sample of radio sources. We identify 44 radio galaxies and\n16 quasars with powers $P>10^{25.5}$ W Hz$^{-1}$ at 150 MHz using cross-matched\nmulti-wavelength information from the AGN and Galaxy Evolution Survey (AGES),\nwhich provides spectroscopic redshifts. We find that LOFAR-detected radio\nsources with steep spectra have projected linear sizes that are on average\n4.4$\\pm$1.4 larger than those with flat spectra. The projected linear sizes of\nradio galaxies are on average 3.1$\\pm$1.0 larger than those of quasars\n(2.0$\\pm$0.3 after correcting for redshift evolution). Combining these results\nwith three previous surveys, we find that the projected linear sizes of radio\ngalaxies and quasars depend on redshift but not on power. The projected linear\nsize ratio does not correlate with either parameter. The LOFAR data is\nconsistent within the uncertainties with theoretical predictions of the\ncorrelation between the quasar fraction and linear size ratio, based on an\norientation-based unification scheme.", "positive": "The hidden side of cosmic star formation at z > 3: Bridging\n optically-dark and Lyman break galaxies with GOODS-ALMA: Our current understanding of the cosmic star formation history at z>3 is\nprimarily based on UV-selected galaxies (i.e., LBGs). Recent studies of\nH-dropouts have revealed that we may be missing a large proportion of star\nformation that is taking place in massive galaxies at z>3. In this work, we\nextend the H-dropout criterion to lower masses to select optically dark/faint\ngalaxies (OFGs), in order to complete the census between LBGs and H-dropouts.\nOur criterion (H> 26.5 mag & [4.5] < 25 mag) combined with a de-blending\ntechnique is designed to select not only extremely dust-obscured massive\ngalaxies but also normal star-forming galaxies. In total, we identified 27 OFGs\nat z_phot > 3 (z_med=4.1) in the GOODS-ALMA field, covering a wide distribution\nof stellar masses with log($M_{\\star}$/$M_{\\odot}$) = 9.4-11.1. We find that up\nto 75% of the OFGs with log($M_{\\star}$/$M_{\\odot}$) = 9.5-10.5 were neglected\nby previous LBGs and H-dropout selection techniques. After performing stacking\nanalyses, the OFGs exhibit shorter gas depletion timescales, slightly lower gas\nfractions, and lower dust temperatures than typical star-forming galaxies.\nTheir SFR_tot (SFR_ IR+SFR_UV) is much larger than SFR_UVcorr (corrected for\ndust extinction), with SFR_tot/SFR_UVcorr = $8\\pm1$, suggesting the presence of\nhidden dust regions in the OFGs that absorb all UV photons. The average dust\nsize measured by a circular Gaussian model fit is R_e(1.13 mm)=1.01$\\pm$0.05\nkpc. We find that the cosmic SFRD at z>3 contributed by massive OFGs is at\nleast two orders of magnitude higher than the one contributed by equivalently\nmassive LBGs. Finally, we calculate the combined contribution of OFGs and LBGs\nto the cosmic SFRD at z=4-5 to be 4 $\\times$ 10$^{-2}$ $M_{\\odot}$\nyr$^{-1}$Mpc$^{-3}$, which is about 0.15 dex (43%) higher than the SFRD derived\nfrom UV-selected samples alone at the same redshift." }, { "anchor": "X-ray metal line emission from the hot circumgalactic medium: probing\n the effects of supermassive black hole feedback: We derive predictions from state-of-the-art cosmological galaxy simulations\nfor the spatial distribution of the hot circumgalactic medium (CGM, ${\\rm\n[0.1-1]R_{200c}}$) through its emission lines in the X-ray soft band\n($[0.3-1.3]$ keV). In particular, we compare IllustrisTNG, EAGLE, and SIMBA and\nfocus on galaxies with stellar mass $10^{10-11.6}\\, \\MSUN$ at $z=0$. The three\nsimulation models return significantly different surface brightness radial\nprofiles of prominent emission lines from ionized metals such as OVII(f),\nOVIII, and FeXVII as a function of galaxy mass. Likewise, the three simulations\npredict varying azimuthal distributions of line emission with respect to the\ngalactic stellar planes, with IllustrisTNG predicting the strongest angular\nmodulation of CGM physical properties at radial range\n${\\gtrsim0.3-0.5\\,R_{200c}}$. This anisotropic signal is more prominent for\nhigher-energy lines, where it can manifest as X-ray eROSITA-like bubbles.\nDespite different models of stellar and supermassive black hole (SMBH)\nfeedback, the three simulations consistently predict a dichotomy between\nstar-forming and quiescent galaxies at the Milky-Way and Andromeda mass range,\nwhere the former are X-ray brighter than the latter. This is a signature of\nSMBH-driven outflows, which are responsible for quenching star formation.\nFinally, we explore the prospect of testing these predictions with a\nmicrocalorimeter-based X-ray mission concept with a large field-of-view. Such a\nmission would probe the extended hot CGM via soft X-ray line emission,\ndetermine the physical properties of the CGM, including temperature, from the\nmeasurement of line ratios, and provide critical constraints on the efficiency\nand impact of SMBH feedback on the CGM.", "positive": "Substructure in the stellar halos of the Aquarius simulations: We characterize substructure in the simulated stellar halos of Cooper et al.\n(2010) which were formed by the disruption of satellite galaxies within the\ncosmological N-body simulations of galactic halos of the Aquarius Project.\nThese stellar halos exhibit a wealth of tidal features: broad overdensities and\nvery narrow faint streams akin to those observed around the Milky Way. The\nsubstructures are distributed anisotropically on the sky, a characteristic that\nshould become apparent in the next generation of photometric surveys. The\nnormalized RMS of the density of stars on the sky appears to be systematically\nlarger for our halos compared to the value estimated for the Milky Way from\nmain sequence turn-off stars in the Sloan Digital Sky Survey. We show that this\nis likely to be due in part to contamination by faint QSOs and redder main\nsequence stars, and might suggest that ~10% of the Milky Way halo stars have\nformed in-situ." }, { "anchor": "Dark Matter as a Trigger for Periodic Comet Impacts: Although statistical evidence is not overwhelming, possible support for an\napproximately 35 million year periodicity in the crater record on Earth could\nindicate a nonrandom underlying enhancement of meteorite impacts at regular\nintervals. A proposed explanation in terms of tidal effects on Oort cloud comet\nperturbations as the Solar System passes through the galactic midplane is\nhampered by lack of an underlying cause for sufficiently enhanced gravitational\neffects over a sufficiently short time interval and by the time frame between\nsuch possible enhancements. We show that a smooth dark disk in the galactic\nmidplane would address both these issues and create a periodic enhancement of\nthe sort that has potentially been observed. Such a disk is motivated by a\nnovel dark matter component with dissipative cooling that we considered in\nearlier work. We show how to evaluate the statistical evidence for periodicity\nby input of appropriate measured priors from the galactic model, justifying or\nruling out periodic cratering with more confidence than by evaluating the data\nwithout an underlying model. We find that, marginalizing over astrophysical\nuncertainties, the likelihood ratio for such a model relative to one with a\nconstant cratering rate is 3.0, which moderately favors the dark disk model.\nOur analysis furthermore yields a posterior distribution that, based on current\ncrater data, singles out a dark matter disk surface density of approximately 10\nsolar masses per square parsec. The geological record thereby motivates a\nparticular model of dark matter that will be probed in the near future.", "positive": "ALMA and VLA measurements of frequency-dependent time lags in\n Sagittarius A*: evidence for a relativistic outflow: Radio and mm-wavelength observations of Sagittarius A* (Sgr A*), the radio\nsource associated with the supermassive black hole at the center of our Galaxy,\nshow that it behaves as a partially self-absorbed synchrotron-emitting source.\nThe measured size of Sgr A* shows that the mm-wavelength emission comes from a\nsmall region and consists of the inner accretion flow and a possible collimated\noutflow. Existing observations of Sgr A* have revealed a time lag between light\ncurves at 43 GHz and 22 GHz, which is consistent with a rapidly expanding\nplasma flow and supports the presence of a collimated outflow from the\nenvironment of an accreting black hole.\n Here we wish to measure simultaneous frequency-dependent time lags in the\nlight curves of Sgr A* across a broad frequency range to constrain direction\nand speed of the radio-emitting plasma in the vicinity of the black hole. Light\ncurves of Sgr A* were taken in May 2012 using ALMA at 100 GHz using the VLA at\n48, 39, 37, 27, 25.5, and 19 GHz. As a result of elevation limits and the\nlongitude difference between the stations, the usable overlap in the light\ncurves is approximately four hours. Although Sgr A* was in a relatively quiet\nphase, the high sensitivity of ALMA and the VLA allowed us to detect and fit\nmaxima of an observed minor flare where flux density varied by ~10%.\n The fitted times of flux density maxima at frequencies from 100 GHz to 19\nGHz, as well as a cross-correlation analysis, reveal a simple\nfrequency-dependent time lag relation where maxima at higher frequencies lead\nthose at lower frequencies. Taking the observed size-frequency relation of Sgr\nA* into account, these time lags suggest a moderately relativistic (lower\nestimates: 0.5c for two-sided, 0.77c for one-sided) collimated outflow." }, { "anchor": "The shape of Fe K$\u03b1$ line emitted from relativistic accretion disc\n around AGN black holes: The relativistically broadened Fe K$\\alpha$ line, originating from the\naccretion disc in a vicinity of a super massive black hole, is observed in only\nless than 50\\% of type 1 Active Galactic Nuclei (AGN). In this study we\ninvestigate could this lack of detections be explained by the effects of\ncertain parameters of the accretion disc and black hole, such as the\ninclination, the inner and outer radius of disc and emissivity index. In order\nto determine how these parameters affect the Fe K $\\alpha$ line shape, we\nsimulated about 60,000 Fe K $\\alpha$ line profiles emitted from the\nrelativistic disc.\n Based on simulated line profiles, we conclude that the lack of the Fe\nK$\\alpha$ line detection in type 1 AGN could, be caused by the specific\nemitting disc parameters, but also by the limits in the spectral resolution and\nsensitivity of the X-ray detectors.", "positive": "Interstellar magnetic cannon targeting the Galactic halo : A young\n bubble at the origin of the Ophiuchus and Lupus molecular complexes: We report the detection of a new Galactic bubble at the interface between the\nhalo and the Galactic disc. We suggest that the nearby Lupus complex and parts\nof the Ophiuchus complex constitute the denser parts of the structure. This\nyoung bubble, < 3 Myr old, could be the remnant of a supernova and expands\ninside a larger HI loop that has been created by the outflows of the Upper\nScorpius OB association. An HI cavity filled with hot X-ray gas is associated\nwith the structure, which is consistent with the Galactic chimney scenario. The\nX-ray emission extends beyond the west and north-west edges of the bubble,\nsuggesting that hot gas outflows are breaching the cavity, possibly through the\nfragmented Lupus complex. Analyses of the polarised radio synchrotron and of\nthe polarised dust emission of the region suggest the connection of the\nGalactic centre spur with the young Galactic bubble. A distribution of HI\nclumps that spatially corresponds well to the cavity boundaries was found at\nV_LSR ~ -100 km/s. Some of these HI clumps are forming jets, which may arise\nfrom the fragmented part of the bubble. We suggest that these clumps might be\n`dripping' cold clouds from the shell walls inside the cavity that is filled\nwith hot ionised gas. It is possible that some of these clumps are magnetised\nand were then accelerated by the compressed magnetic field at the edge of the\ncavity. Such a mechanism would challenge the Galactic accretion and fountain\nmodel, where high-velocity clouds are considered to be formed at high Galactic\nlatitude from hot gas flows from the Galactic plane." }, { "anchor": "Creating lenticular galaxies with major mergers: Lenticular galaxies (S0s) represent the majority of early-type galaxies in\nthe local Universe, but their formation channels are still poorly understood.\nWhile galaxy mergers are obvious pathways to suppress star formation and\nincrease bulge sizes, the marked parallelism between spiral and lenticular\ngalaxies (e.g. photometric bulge-disc coupling) seemed to rule out a potential\nmerger origin. Here, we summarise our recent work in which we have shown,\nthrough N-body numerical simulations, that disc-dominated lenticulars can\nemerge from major mergers of spiral galaxies, in good agreement with\nobservational photometric scaling relations. Moreover, we show that mergers\nsimultaneously increase the light concentration and reduce the angular momentum\nrelative to their spiral progenitors. This explains the mismatch in angular\nmomentum and concentration between spirals and lenticulars recently revealed by\nCALIFA observations, which is hard to reconcile with simple fading mechanisms\n(e.g. ram-pressure stripping).", "positive": "Determination of Planetary Nebulae angular diameters from radio\n continuum Spectral Energy Distribution modeling: Powerful new, high resolution, high sensitivity, multi-frequency, wide-field\nradio surveys such as the Australian Square Kilometre Array Pathfinder (ASKAP)\nEvolutionary Map of the Universe (EMU) are emerging. They will offer fresh\nopportunities to undertake new determinations of useful parameters for various\nkinds of extended astrophysical phenomena. Here, we consider specific\napplication to angular size determinations of Planetary Nebulae (PNe) via a new\nradio continuum Spectral Energy Distribution (SED) fitting technique. We show\nthat robust determinations of angular size can be obtained, comparable to the\nbest optical and radio observations but with the potential for consistent\napplication across the population. This includes unresolved and/or heavily\nobscured PNe that are extremely faint or even non-detectable in the optical." }, { "anchor": "Early-type galaxy density profiles from IllustrisTNG: II. Evolutionary\n trend of the total density profile: We study the evolutionary trend of the total density profile of early-type\ngalaxies (ETGs) in IllustrisTNG. To this end, we trace ETGs from $z=0$ to $z=4$\nand measure the power-law slope $\\gamma^{\\prime}$ of the total density profile\nfor their main progenitors. We find that their $\\gamma^{\\prime}$ steepen on\naverage during $z\\sim4-2$, then becoming shallower until $z=1$, after which\nthey remain almost constant, aside from a residual trend of becoming shallower\ntowards $z=0$. We also compare to a statistical sample of ETGs at different\nredshifts, selected based on their luminosity profiles and stellar masses. Due\nto different selection effects, the average slopes of the statistical samples\nfollow a modified evolutionary trend. They monotonically decrease since $z=3$,\nand after $z\\approx 1$, they remain nearly invariant with a mild increase\ntowards $z=0$. These evolutionary trends are mass-dependent for both samples,\nwith low-mass galaxies having in general steeper slopes than their more massive\ncounterparts. Galaxies that transitioned to ETGs more recently have steeper\nmean slopes as they tend to be smaller and more compact at any given redshift.\nBy analyzing the impact of mergers and AGN feedback on the progenitors'\nevolution, we conjecture a multi-phase path leading to isothermality in ETGs:\ndissipation associated with rapid wet mergers tends to steepen\n$\\gamma^{\\prime}$ from $z=4$ to $z=2$, whereas subsequent AGN feedback\n(especially in the kinetic mode) makes $\\gamma^{\\prime}$ shallower again from\n$z=2$ to $z=1$. Afterwards, passive evolution from $z=1$ to $z=0$, mainly\nthrough gas-poor mergers, mildly decreases $\\gamma^{\\prime}$ and maintains the\noverall mass distribution close to isothermal.", "positive": "$Spitzer$-selected $z > 1.3$ protocluster candidates in the LSST Deep\n Drilling Fields: We have identified 189 candidate $z > 1.3$ protoclusters and clusters in the\nLSST Deep Drilling Fields. This sample will enable the measurement of the metal\nenrichment and star formation history of clusters during their early assembly\nperiod through the direct measurement of the rate of supernovae identified\nthrough the LSST. The protocluster sample was selected from galaxy\noverdensities in a $Spitzer$/IRAC colour-selected sample using criteria that\nwere optimised for protocluster purity using a realistic lightcone. Our tests\nreveal that $60-80\\%$ of the identified candidates are likely to be genuine\nprotoclusters or clusters, which is corroborated by a $\\sim4\\sigma$ stacked\nX-ray signal from these structures. We provide photometric redshift estimates\nfor 47 candidates which exhibit strong peaks in the photo-$z$ distribution of\ntheir candidate members. However, the lack of a photo-$z$ peak does not mean a\ncandidate is not genuine, since we find a stacked X-ray signal of similar\nsignificance from both the candidates that exhibit photo-$z$ peaks and those\nthat do not. Tests on the lightcone reveal that our pursuit of a pure sample of\nprotoclusters results in that sample being highly incomplete ($\\sim4\\%$) and\nheavily biased towards larger, richer, more massive, and more centrally\nconcentrated protoclusters than the total protocluster population. Most\n($\\sim75\\%$) of the selected protoclusters are likely to have a maximum\ncollapsed halo mass of between $10^{13}-10^{14}$ M$_{\\odot}$, with only\n$\\sim25\\%$ likely to be collapsed clusters above $10^{14}$ M$_{\\odot}$.\nHowever, the aforementioned bias ensures our sample is $\\sim50\\%$ complete for\nstructures that have already collapsed into clusters more massive than\n$10^{14}$ M$_{\\odot}$." }, { "anchor": "A deep look at the nuclear region of UGC 5101 through high angular\n resolution mid-IR data with GTC/CanariCam: We present an analysis of the nuclear infrared (IR, 1.6 to 18 $\\mu$m)\nemission of the ultraluminous IR galaxy UGC 5101 to derive the properties of\nits active galactic nucleus (AGN) and its obscuring material. We use new mid-IR\nhigh angular resolution ($0.3-0.5$ arcsec) imaging using the Si-2 filter\n($\\lambda_{C}=8.7\\, \\mu$m) and $7.5-13$ $\\mu$m spectroscopy taken with\nCanariCam (CC) on the 10.4m Gran Telescopio CANARIAS. We also use archival\nHST/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate\nthe near- and mid-IR unresolved nuclear emission by modelling the imaging data\nwith GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law\ncomponent, which represents the emission due to dust heated by the AGN, and a\nstarburst component, both affected by foreground extinction. We model the\nresulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum\nwith the CLUMPY torus models of Nenkova et al. The derived geometrical\nproperties of the torus, including the large covering factor and the high\nforeground extinction needed to reproduce the deep $9.7\\, \\mu$m silicate\nfeature, are consistent with the lack of strong AGN signatures in the optical.\nWe derive an AGN bolometric luminosity $L_{bol}\\sim1.9\\times10^{45}\\,$erg\ns$^{-1}$ that is in good agreement with other estimates in the literature.", "positive": "The Arecibo Galaxy Environment Survey XII : Optically dark HI clouds in\n the Leo I Group: Using data from the Arecibo Galaxy Environment Survey, we report the\ndiscovery of five HI clouds in the Leo I group without detected optical\ncounterparts. Three of the clouds are found midway between M96 and M95, one is\nonly 10$^{\\prime}$ from the south-east side of the well-known Leo Ring, and the\nfifth is relatively isolated. HI masses range from 2.6$\\times$10$^{6}$ -\n9.0$\\times$10$^{6}$M$_{\\odot}$ and velocity widths (W50) from 16 - 42 km/s.\nAlthough a tidal origin is the most obvious explanation, this formation\nmechanism faces several challenges. For the most isolated cloud, the\ndifficulties are its distance from neighbouring galaxies and the lack of any\nsigns of disturbance in the HI discs of those systems. Some of the clouds also\nappear to follow the baryonic Tully-Fisher relation between mass and velocity\nwidth for normal, stable galaxies which is not expected if they are tidal in\norigin. Three clouds are found between M96 and M95 which have no optical\ncounterparts, but have otherwise similar properties and location to the\noptically detected galaxy LeG 13. While overall we favour a tidal debris\nscenario to explain the clouds, we cannot rule out a primordial origin. If the\nclouds were produced in the same event that gave rise to the Leo Ring, they may\nprovide important constraints on any model attempting to explain that structure" }, { "anchor": "Kinematics and dynamics of Gaia red clump stars: We analyse the kinematics and dynamics of a homogeneous sample of red clump\nstars selected from the second Gaia data release catalogue in the direction of\nthe Galactic poles. The level of completeness of the sample at heights between\n0.6 and 3.5 kpc is asserted by comparison with the 2 Micron All Sky Survey\ncatalogue. We show that both the density distribution and velocity dispersion\nare significantly more perturbed in the North than in the South, in all\nanalysed regions of our Galactic neighbourhoods. We provide a detailed\nassessment of these North-South asymmetries at large heights. We then proceed\nto evaluate how such asymmetries could affect determinations of the dynamical\nmatter density under equilibrium assumptions. We find that a Jeans analysis\ndelivers relatively similar vertical forces and integrated dynamical surface\ndensities at large heights above the plane in both hemispheres. At these\nheights, the densities of stars and gas are very low and the surface density is\nlargely dominated by dark matter, which allows to estimate, separately in the\nNorth and South, the local dark matter density derived under equilibrium\nassumptions. In the presence of vertical perturbations, such values should be\nconsidered as an upper limit. This Jeans analysis yields values of the local\ndark matter density above 2~kpc, $\\rho_{\\rm DM} \\sim 0.013 \\, {\\rm\nM}_\\odot/{\\rm pc}^3$ ($ \\sim 0.509 \\, {\\rm GeV/cm}^3$) in the perturbed\nNorthern hemisphere, and $\\rho_{\\rm DM} \\sim 0.010 \\, {\\rm M}_\\odot/{\\rm pc}^3$\n($ \\sim 0.374 \\, {\\rm GeV/cm}^3$) in the much less perturbed South. As a\ncomparison, we determine the local dark matter density by fitting a global\nphase-space distribution to the data. We end up with a value in the range of\n$\\rho_{\\rm DM} \\sim 0.011 - 0.014 \\, {\\rm M}_\\odot/{\\rm pc}^3$ in global\nagreement with Jeans analysis.", "positive": "Ionised gas kinematics and dynamical masses of $z\\gtrsim6$ galaxies from\n JADES/NIRSpec high-resolution spectroscopy: We explore the kinematic gas properties of six $5.51$ thus far. The cold gas masses implied by the\nobserved star formation rates are $\\sim 10\\times$ larger than the stellar\nmasses. We find that their ionised gas is spatially resolved by JWST, with\nevidence for broadened lines and spatial velocity gradients. Using a simple\nthin-disc model, we fit these data with a novel forward modelling software that\naccounts for the complex geometry, point spread function, and pixellation of\nthe NIRSpec instrument. We find the sample to include both rotation- and\ndispersion-dominated structures, as we detect velocity gradients of $v(r_{\\rm\ne})\\approx100-150\\,{\\rm km\\,s^{-1}}$, and find velocity dispersions of\n$\\sigma_0\\approx 30-70\\,{\\rm km\\,s^{-1}}$ that are comparable to those at\ncosmic noon. The dynamical masses implied by these models ($M_{\\rm\ndyn}\\sim10^{9-10}\\,{\\rm M_\\odot}$) are larger than the stellar masses by up to\na factor 40, and larger than the total baryonic mass (gas + stars) by a factor\nof $\\sim 3$. Qualitatively, this result is robust even if the observed velocity\ngradients reflect ongoing mergers rather than rotating discs. Unless the\nobserved emission line kinematics is dominated by outflows, this implies that\nthe centres of these galaxies are dark-matter dominated or that star formation\nis $3\\times$ less efficient, leading to higher inferred gas masses." }, { "anchor": "Velocity Gradients as a Tracer for Magnetic Fields: Strong Alfv\\'enic turbulence develops eddy-like motions perpendicular to the\nlocal direction of magnetic fields. This local alignment induces velocity\ngradients perpendicular to the local direction of the magnetic field. We use\nthis fact to propose a new technique of studying the direction of magnetic\nfields from observations, the Velocity Gradient Technique. We test our idea by\nemploying the synthetic observations obtained via 3D MHD numerical simulations\nfor different sonic and Alfv\\'en Mach numbers. We calculate the velocity\ngradient, $\\mathbf{\\Omega}$, using the velocity centroids. We find that\n$\\mathbf{\\Omega}$ traces the projected magnetic field best for the synthetic\nmaps obtained with sub-Alfv\\'enic simulations providing good point-wise\ncorrespondence between the magnetic field direction and that of\n$\\mathbf{\\Omega}$. The reported alignment is much better than the alignment\nbetween the density gradients and the magnetic field and we demonstrated that\nit can be used to find the magnetic field strength using the\nChandrasekhar-Fermi method. Our study opens a new way of studying magnetic\nfields using spectroscopic data.", "positive": "Relation between positional & strength asymmetries of double radio\n sources associated with active galaxies: We bring out the identity between two ways of defining a single parameter to\ncombine positional & strength asymmetries of extended extragalactic double\nradio sources associated with active galaxies. Thus, (r.s - 1)/[(1 + r).(1 +\ns)], combining arm ratio r (defined to be <= 1, i.e., shorter to longer arm) &\nstrength ratio s (in the sense closer to farther, so that it may be <, > or =\n1), is identical to -(1/2)[(1 - fr)/(1 + fr) - t], where fr is strength ratio\ndefined >= 1 (i.e., stronger to weaker), & t = +/- (Q - 1)/(Q + 1), +/- signs\napplying respectively to doubles with closer hotspot fainter & those with\ncloser hotspot brighter, while Q is arm ratio defined >= 1.\n Keywords: active galaxies - double radio sources - bilateral symmetry - arm\nratio - flux ratio" }, { "anchor": "High-Resolution Spectroscopy of Extremely Metal-Poor Stars in the Least\n Evolved Galaxies: Ursa Major II and Coma Berenices: We present Keck/HIRES observations of six metal-poor stars in two of the\nultra-faint dwarf galaxies orbiting the Milky Way, Ursa Major II and Coma\nBerenices. These observations include the first high-resolution spectroscopic\nobservations of extremely metal-poor stars ([Fe/H]<-3.0) stars not belonging to\nthe Milky Way (MW) halo field star population. We obtain abundance measurements\nand upper limits for 26 elements between carbon and europium. The entire sample\nof stars spans a range of -3.2<[Fe/H]<-2.3, and we confirm that each galaxy\ncontains a large intrinsic spread of Fe abundances. A comparison with MW halo\nstars of similar metallicities reveals substantial agreement between the\nabundance patterns of the ultra-faint dwarf galaxies and the MW halo for the\nlight, alpha and iron-peak elements (C to Zn). This agreement contrasts with\nthe results of earlier studies of more metal-rich stars (-2.5<[Fe/H]<-1.0) in\nmore luminous dwarf spheroidal galaxies (dSphs), which found significant\nabundance discrepancies with respect to the MW halo data. The abundances of\nneutron-capture elements (Sr to Eu) in the ultra-faint dwarf galaxies are\nextremely low, consistent with the most metal-poor halo stars, but not with the\ntypical halo abundance pattern at [Fe/H]>-3.0. Our results are broadly\nconsistent with a galaxy formation model that predicts that massive dwarf\ngalaxies are the source of the metal-rich component ([Fe/H]>-2.5) of the MW\nhalo, but we also suggest that the faintest known dwarfs may be the primary\ncontributors to the metal-poor end of the MW halo metallicity distribution.", "positive": "The spiral arms of galaxies: The most important theory of the spiral arms of galaxies is the density wave\ntheory based on the Lin-Shu dispersion relation. However, the density waves\nmove with the group velocity towards the inner Lindblad resonance and tend to\ndisappear. Various mechanisms to replenish the spiral waves have been proposed.\nNonlinear effects play an important role near the inner and outer Lindblad\nresonances and corotation. The orbits supporting the spiral arms are precessing\nellipses in normal galaxies that extend up to the 4/1 resonance. On the other\nhand, in barred galaxies the spiral arms extend along the manifolds of the\nunstable periodic orbits at the ends of the bar and they are composed of\nchaotic orbits. However these chaotic orbits can be found analytically." }, { "anchor": "The first supermassive black holes: We briefly review the historical development of the ideas regarding the first\nsupermassive black hole seeds, the physics of their formation and radiative\nfeedback, recent theoretical and observational progress, and our outlook for\nthe future.", "positive": "Accretion of pristine gas and dilution during the formation of\n multiple-population globular clusters: We study the interaction of the early spherical GC wind powered by Type II\nsupernovae (SNe II) with the surrounding ambient medium consisting of the\ngaseous disk of a star forming galaxy at redshift z ~> 2. The bubble formed by\nthe wind eventually breaks out of the disk, and most of the wind moves directly\nout of the galaxy and is definitively lost. The fraction of the wind moving\nnearly parallel to the galactic plane carves a hole in the disk which will\ncontract after the end of the SN activity. During the interval of time between\nthe end of the SN explosions and the \"closure\" of the hole, very O-poor stars\n(the Extreme population) can form out of the super-AGB (asymptotic giant\nbranch) ejecta collected in the GC center. Once the hole contracts, the AGB\nejecta mix with the pristine gas, allowing the formation of stars with an\noxygen abundance intermediate between that of the very O-poor stars and that of\nthe pristine gas. We show that this mechanism may explain why Extreme\npopulations are present only in massive clusters, and can also produce a\ncorrelation between the spread in helium and the cluster mass. Finally, we also\nexplore the possibility that our proposed mechanism can be extended to the case\nof multiple populations showing bimodality in the iron content, with the\npresence of two populations characterized by a small difference in [Fe/H]. Such\na result can be obtained taking into account the contribution of delayed SN II." }, { "anchor": "Physical properties and scaling relations of molecular clouds: the\n effect of stellar feedback: Using hydrodynamical simulations of entire galactic discs similar to the\nMilky Way, reaching 4.6pc resolution, we study the origins of observed physical\nproperties of giant molecular clouds (GMCs). We find that efficient stellar\nfeedback is a necessary ingredient in order to develop a realistic interstellar\nmedium (ISM), leading to molecular cloud masses, sizes, velocity dispersions\nand virial parameters in excellent agreement with Milky Way observations. GMC\nscaling relations observed in the Milky Way, such as the mass-size ($M$--$R$),\nvelocity dispersion-size ($\\sigma$--$R$), and the $\\sigma$--$R\\Sigma$\nrelations, are reproduced in a feedback driven ISM when observed in projection,\nwith $M\\propto R^{2.3}$ and $\\sigma\\propto R^{0.56}$. When analysed in 3D, GMC\nscaling relations steepen significantly, indicating potential limitations of\nour understanding of molecular cloud 3D structure from observations.\nFurthermore, we demonstrate how a GMC population's underlying distribution of\nvirial parameters can strongly influence the scatter in derived scaling\nrelations. Finally, we show that GMCs with nearly identical global properties\nexist in different evolutionary stages, where a majority of clouds being either\ngravitationally bound or expanding, but with a significant fraction being\ncompressed by external ISM pressure, at all times.", "positive": "The ESO UVES Advanced Data Products Quasar Sample-V. Identifying the\n Galaxy Counterpart to the sub-Damped Ly-alpha System towards Q2239-2949: Gas flows in and out of galaxies are one of the key unknowns in todays'\ngalaxy evolution studies. Because gas flows carry mass, energy and metals, they\nare believed to be closely connected to the star formation history of galaxies.\nMost of these processes take place in the circum-galactic medium (CGM) which\nremains challenging to observe in emission. A powerful tool to study the CGM\ngas is offered by combining observations of the gas traced by absorption lines\nin quasar spectra with detection of the stellar component of the same\nabsorbing-galaxy. To this end, we have targeted the zabs=1.825 sub-Damped\nLy-alpha absorber (sub-DLA) towards the zem=2.102 quasar 2dF J 223941.8-294955\n(hereafter Q2239-2949) with the ESO VLT/X-Shooter spectrograph. Our aim is to\ninvestigate the relation between its properties in emission and in absorption.\nThe derived metallicity of the sub-DLA with log N(HI) = 19.84+/-0.14 cm-2 is\n[M/H] >-0.75. Using the Voigt profile optical depth method, we measure\nDelta_v90(FeII)=64 kms-1. The sub-DLA galaxy counterpart is located at an\nimpact parameter of 2.\"4+/-0.\"2 (20.8+/-1.7 kpc at z = 1.825). We have detected\nLy-alpha and marginal [OII] emissions. The mean measured flux of the Ly-alpha\nline is F(Ly-alpha) ~ 5.7x10^-18 erg s-1 cm-2 A-1, corresponding to a dust\nuncorrected SFR of ~ 0.13 M(solar) yr-1." }, { "anchor": "On the size of the CO-depletion radius in the IRDC G351.77-0.51: An estimate of the degree of CO-depletion ($f_D$) provides information on the\nphysical conditions occurring in the innermost and densest regions of molecular\nclouds. A key parameter in these studies is the size of the depletion radius,\ni.e. the radius within which the C-bearing species, and in particular CO, are\nlargely frozen onto dust grains. A strong depletion state (i.e. $f_D>10$, as\nassumed in our models) is highly favoured in the innermost regions of dark\nclouds, where the temperature is $<20$ K and the number density of molecular\nhydrogen exceeds a few $\\times$10$^{4}$ cm$^{-3}$. In this work, we estimate\nthe size of the depleted region by studying the Infrared Dark Cloud (IRDC)\nG351.77-0.51. Continuum observations performed with the $Herschel$ $Space$\n$Observatory$ and the $LArge$ $APEX$ $BOlometer$ $CAmera$, together with APEX\nC$^{18}$O and C$^{17}$O J=2$\\rightarrow$1 line observations, allowed us to\nrecover the large-scale beam- and line-of-sight-averaged depletion map of the\ncloud. We built a simple model to investigate the depletion in the inner\nregions of the clumps in the filament and the filament itself. The model\nsuggests that the depletion radius ranges from 0.02 to 0.15 pc, comparable with\nthe typical filament width (i.e.$\\sim$0.1 pc). At these radii, the number\ndensity of H$_2$ reaches values between 0.2 and 5.5$\\times$10$^{5}$ cm$^{-3}$.\nThese results provide information on the approximate spatial scales on which\ndifferent chemical processes operate in high-mass star-forming regions and also\nsuggest caution when using CO for kinematical studies in IRDCs.", "positive": "The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs: We analyze radial velocity observations of the 12 extremely low-mass <0.25\nMsol white dwarfs (WDs) in the MMT Hypervelocity Star Survey. Eleven of the 12\nWDs are binaries with orbital periods shorter than 14 hours; the one\nnon-variable WD is possibly a pole-on system among our non-kinematically\nselected targets. Our sample is unique: it is complete in a well-defined range\nof apparent magnitude and color. The orbital mass functions imply that the\nunseen companions are most likely other WDs, although neutron star companions\ncannot be excluded. Six of the 11 systems with orbital solutions will merge\nwithin a Hubble time due to the loss of angular momentum through gravitational\nwave radiation. The quickest merger is J0923+3028, a g=15.7 ELM WD binary with\na 1.08 hr orbital period and a <130 Myr merger time. The chance of a supernova\nIa event among our ELM WDs is only 1%-7%, however. Three binary systems\n(J0755+4906, J1233+1602, and J2119-0018) have extreme mass ratios and will most\nlikely form stable mass-transfer AM CVn systems. Two of these objects, SDSS\nJ1233+1602 and J2119-0018, are the lowest surface gravity WDs ever found; both\nshow Ca II absorption likely from accretion of circumbinary material. We\npredict that at least one of our WDs is an eclipsing detached double WD system,\nimportant for constraining helium core WD models." }, { "anchor": "How fast do young star clusters expel their natal gas?: Estimating the\n upper limit of the gas expulsion time-scale: Formation of massive stars within embedded star clusters starts a complex\ninterplay between their feedback, inflowing gas and stellar dynamics, which\noften includes close stellar encounters. Hydrodynamical simulations usually\nresort to substantial simplifications to model embedded clusters. Here, we\naddress the simplification which approximates the whole star cluster by a\nsingle sink particle, which completely neglects the internal stellar dynamics.\nIn order to model the internal stellar dynamics, we implement a Hermite\npredictor-corrector integration scheme to the hydrodynamic code FLASH. As we\nillustrate by a suite of tests, this integrator significantly outperforms the\ncurrent leap-frog scheme, and it is able to follow the dynamics of small\ncompact stellar systems without the necessity to soften the gravitational\npotential. We find that resolving individual massive stars instead of\nrepresenting the whole cluster by a single energetic source has a profound\ninfluence on the gas component: for clusters of mass less than $\\lesssim 3\n\\times 10^3 M_{\\odot}$, it slows gas expulsion by a factor of $\\approx 5$ to\n$\\approx 1$ Myr, and it results in substantially more complex gas structures.\nWith increasing cluster mass (up to $\\approx 3\\times 10^3 M_{\\odot}$), the gas\nexpulsion time-scale slightly decreases. However, more massive clusters\n($\\gtrsim 5\\times 10^3 M_{\\odot}$) are unable to clear their natal gas with\nphotoionising radiation and stellar winds only if they form with a star\nformation efficiency (SFE) of $1/3$. This implies that the more massive\nclusters are either cleared with another feedback mechanism or they form with a\nSFE higher than $1/3$.", "positive": "The Fornax 3D project: Non-linear colour-metallicity relation of\n globular clusters: Globular cluster (GC) systems of massive galaxies often show a bimodal colour\ndistribution. This has been interpreted as a metallicity bimodality, created by\na two-stage galaxy formation where the red, metal-rich GCs were formed in the\nparent halo and the blue metal-poor GCs were accreted. This interpretation,\nhowever, crucially depends on the assumption that GCs are exclusively old\nstellar systems with a linear colour-metallicity relation (CZR). The shape of\nthe CZR and range of GC ages are currently under debate, because their study\nrequires high quality spectra to derive reliable stellar population properties.\nWe determined metallicities with full spectral fitting from a sample of 187 GCs\nwith high spectral signal-to-noise ratio in 23 galaxies of the Fornax cluster\nthat were observed as part of the Fornax 3D project. The derived CZR from this\nsample is non-linear and can be described by a piecewise linear function with a\nbreak point at ($g - z$) $\\sim$ 1.1 mag. The less massive galaxies in our\nsample ($M_\\ast < 10^{10} M_\\odot$) appear to have slightly younger GCs, but\nthe shape of the CZR is insensitive to the GC ages. Although the least massive\ngalaxies lack red, metal-rich GCs, a non-linear CZR is found irrespective of\nthe galaxy mass, even in the most massive galaxies ($M_\\ast \\geq 10^{11}\nM_\\odot$). Our CZR predicts narrow unimodal GC metallicity distributions for\nlow mass and broad unimodal distributions for very massive galaxies, dominated\nby a metal-poor and metal-rich peak, respectively, and bimodal distributions\nfor galaxies with intermediate masses (10$^{10}$ $\\leq$ $M_\\ast < 10^{11}\nM_\\odot$) as a consequence of the relative fraction of red and blue GCs. The\ndiverse metallicity distributions challenge the simple differentiation of GC\npopulations solely based on their colour." }, { "anchor": "Emission from the Ionized Gaseous Halos of Low Redshift Galaxies and\n Their Neighbors: Using a sample of nearly half a million galaxies, intersected by over 8\nmillion lines of sight from the Sloan Digital Sky Survey Data Release 12, we\nextend our previous study of the recombination radiation emitted by the gaseous\nhalos of nearby galaxies. We identify an inflection in the radial profile of\nthe H$\\alpha$+N[{\\small II}] radial emission profile at a projected radius of\n$\\sim 50$ kpc and suggest that beyond this radius the emission from ionized gas\nin spatially correlated halos dominates the profile. We confirm that this is a\nviable hypothesis using results from a highly simplified theoretical treatment\nin which the dark matter halo distribution from cosmological simulations is\nstraightforwardly populated with gas. Whether we fit the fraction of halo gas\nin a cooler (T $= 12,000$ K), smooth ($c = 1$) component (0.26 for galaxies\nwith M$_* = 10^{10.88}$ M$_\\odot$ and 0.34 for those with M$_* = 10^{10.18}$\nM$_\\odot$) or take independent values of this fraction from published\nhydrodynamical simulations (0.19 and 0.38, respectively), this model\nsuccessfully reproduces the radial location and amplitude of the observed\ninflection. We also observe that the physical nature of the gaseous halo\nconnects to primary galaxy morphology beyond any relationship to the galaxy's\nstellar mass and star formation rate. We explore whether the model reproduces\nbehavior related to the central galaxy's stellar mass, star formation rate, and\nmorphology. We find that it is unsuccessful in reproducing the observations at\nthis level of detail and discuss various shortcomings of our simple model that\nmay be responsible.", "positive": "Stellar populations, stellar masses and the formation of galaxy bulges\n and discs at $z < 3$ in CANDELS: We present a multi-component structural analysis of the internal structure of\n$1074$ high redshift massive galaxies at $13sigma when considering\nthe SFR occurring in both the tail and disk of galaxies. The enhancement is\nretrieved also on local scales: considering spatially resolved data, ram\npressure stripped galaxies overall have large {\\Sigma}SFR values, especially\nfor Sigma_*>10^7.5M_sun kpc~2. RPS seems to leave the same imprint on the\nSFR-M* and Sigma_SFR-Sigma_* relations both in the Local Universe and at\nz~0.35." }, { "anchor": "Blue Stragglers as tracers of the dynamical state of two clusters in the\n Small Magellanic Cloud: NGC 339 and NGC 419: The level of central segregation of Blue Straggler stars proved to be an\nexcellent tracer of the dynamical evolution of old star clusters (the so-called\n\"dynamical clock\"), both in the Milky Way and in the Large Magellanic Cloud.\nThe $A^{+}$ parameter, used to measure the Blue Stragglers degree of\nsegregation, has in fact been found to strongly correlate with the parent\ncluster central relaxation time. Here we studied the Blue-Straggler population\nof two young stellar systems in the Small Magellanic Cloud, namely NGC 339\n(which is 6 Gyr old) and NGC 419 (with an age of only 1.5 Gyr), in order to\nstudy their dynamical state. Thanks to multi-epoch, high angular resolution\nHubble Space Telescope observations available for both clusters, we took\nadvantage of the stellar proper motions measured in the regions of the two\nsystems and we selected a population of likely cluster members, removing the\nstrong contamination from Small Magellanic Cloud stars. This enabled us to\nstudy, with unprecedented accuracy, the radial distribution of Blue Stragglers\nin these two extragalactic clusters and to measure their dynamical age. As\nexpected for such young clusters, we found that both systems are poorly evolved\nfrom the dynamical point of view, also fully confirming that the $A^{+}$\nparameter is a sensitive \"clock hand\" even in the dynamically-young regime.", "positive": "Probing the High-Redshift Universe with SPICA: Toward the Epoch of\n Reionization and Beyond: With the recent discovery of a dozen dusty star-forming galaxies and around\n30 quasars at z>5 that are hyper-luminous in the infrared ($\\mu$$L_{\\rm\nIR}>10^{13}$ L$_{\\odot}$, where $\\mu$ is a lensing magnification factor), the\npossibility has opened up for SPICA, the proposed ESA M5 mid-/far-infrared\nmission, to extend its spectroscopic studies toward the epoch of reionization\nand beyond. In this paper, we examine the feasibility and scientific potential\nof such observations with SPICA's far-infrared spectrometer SAFARI, which will\nprobe a spectral range (35-230 $\\mu$m) that will be unexplored by ALMA and\nJWST. Our simulations show that SAFARI is capable of delivering good-quality\nspectra for hyper-luminous infrared galaxies (HyLIRGs) at z=5-10, allowing us\nto sample spectral features in the rest-frame mid-infrared and to investigate a\nhost of key scientific issues, such as the relative importance of star\nformation versus AGN, the hardness of the radiation field, the level of\nchemical enrichment, and the properties of the molecular gas. From a broader\nperspective, SAFARI offers the potential to open up a new frontier in the study\nof the early Universe, providing access to uniquely powerful spectral features\nfor probing first-generation objects, such as the key cooling lines of\nlow-metallicity or metal-free forming galaxies (fine-structure and H2 lines)\nand emission features of solid compounds freshly synthesized by Population III\nsupernovae. Ultimately, SAFARI's ability to explore the high-redshift Universe\nwill be determined by the availability of sufficiently bright targets (whether\nintrinsically luminous or gravitationally lensed). With its launch expected\naround 2030, SPICA is ideally positioned to take full advantage of upcoming\nwide-field surveys such as LSST, SKA, Euclid, and WFIRST, which are likely to\nprovide extraordinary targets for SAFARI." }, { "anchor": "A 5x10^9 Solar Mass Black Hole in NGC 1277 from Adaptive Optics\n Spectroscopy: The nearby lenticular galaxy NGC 1277 is thought to host one of the largest\nblack holes known, however the black hole mass measurement is based on low\nspatial resolution spectroscopy. In this paper, we present Gemini Near-infrared\nIntegral Field Spectrometer observations assisted by adaptive optics. We map\nout the galaxy's stellar kinematics within ~440 pc of the nucleus with an\nangular resolution that allows us to probe well within the region where the\npotential from the black hole dominates. We find that the stellar velocity\ndispersion rises dramatically, reaching ~550 km/s at the center. Through\norbit-based, stellar-dynamical models we obtain a black hole mass of (4.9 \\pm\n1.6) x 10^9 Msun (1-sigma uncertainties). Although the black hole mass\nmeasurement is smaller by a factor of ~3 compared to previous claims based on\nlarge-scale kinematics, NGC 1277 does indeed contain one of the most massive\nblack holes detected to date, and the black hole mass is an order of magnitude\nlarger than expectations from the empirical relation between black hole mass\nand galaxy luminosity. Given the galaxy's similarities to the higher redshift\n(z~2) massive quiescent galaxies, NGC 1277 could be a relic, passively evolving\nsince that period. A population of local analogs to the higher redshift\nquiescent galaxies that also contain over-massive black holes may suggest that\nblack hole growth precedes that of the host galaxy.", "positive": "Gibbs Point Process Model for Young Star Clusters in M33: We demonstrate the power of Gibbs point process models from the spatial\nstatistics literature when applied to studies of resolved galaxies. We conduct\na rigorous analysis of the spatial distributions of objects in the star\nformation complexes of M33, including giant molecular clouds (GMCs) and young\nstellar cluster candidates (YSCCs). We choose a hierarchical model structure\nfrom GMCs to YSCCs based on the natural formation hierarchy between them. This\napproach circumvents the limitations of the empirical two-point correlation\nfunction analysis by naturally accounting for the inhomogeneity present in the\ndistribution of YSCCs. We also investigate the effects of GMCs' properties on\ntheir spatial distributions. We confirm that the distribution of GMCs and YSCCs\nare highly correlated. We found that the spatial distributions of YSCCs reaches\na peak of clustering pattern at ~250 pc scale compared to a Poisson process.\nThis clustering mainly occurs in regions where the galactocentric distance\n>~4.5 kpc. Furthermore, the galactocentric distance of GMCs and their mass have\nstrong positive effects on the correlation strength between GMCs and YSCCs. We\noutline some possible implications of these findings for our understanding of\nthe cluster formation process." }, { "anchor": "Constraints on free-free emission from Anomalous Microwave Emission\n Sources in the Perseus Molecular Cloud: We present observations performed with the Green Bank Telescope at 1.4 and 5\nGHz of three strips coincident with the anomalous microwave emission features\npreviously identified in the Perseus molecular cloud at 33 GHz with the Very\nSmall Array. With these observations we determine the level of the low\nfrequency (~1 - 5 GHz) emission. We do not detect any significant extended\nemission in these regions and we compute conservative 3\\sigma upper limits on\nthe fraction of free-free emission at 33 GHz of 27%, 12%, and 18% for the three\nstrips, indicating that the level of the emission at 1.4 and 5 GHz cannot\naccount for the emission observed at 33 GHz. Additionally, we find that the low\nfrequency emission is not spatially correlated with the emission observed at 33\nGHz. These results indicate that the emission observed in the Perseus molecular\ncloud at 33 GHz, is indeed in excess over the low frequency emission, hence\nconfirming its anomalous nature.", "positive": "Gravitational eigenstates in weak gravity I: dipole decay rates of\n charged particles: The experimental demonstration that neutrons can reside in gravitational\nquantum stationary states formed in the gravitational field of the Earth\nindicates a need to examine in more detail the general theoretical properties\nof gravitational eigenstates. Despite the almost universal study of quantum\ntheory applied to atomic and molecular states very little work has been done to\ninvestigate the properties of the hypothetical stationary states that should\nexist in similar types of gravitational central potential wells, particularly\nthose with large quantum numbers. In this first of a series of papers, we\nattempt to address this shortfall by developing analytic, non-integral\nexpressions for the electromagnetic dipole state-to-state transition rates of\ncharged particles for any given initial and final gravitational quantum states.\nThe expressions are non-relativistic and hence valid provided the eigenstate\nwavefunctions do not extend significantly into regions of strong gravity. The\nformulae may be used to obtain tractable approximations to the transition rates\nthat can be used to give general trends associated with certain types of\ntransitions. Surprisingly, we find that some of the high angular momentum\neigenstates have extremely long lifetimes and a resulting stability that belies\nthe multitude of channels available for state decay." }, { "anchor": "Far-infrared line spectra of active galaxies from the Herschel/PACS\n Spectrometer: the complete database: We present a coherent database of spectroscopic observations of far-IR\nfine-structure lines from the Herschel/PACS archive for a sample of 170 local\nAGN, plus a comparison sample of 20 starburst galaxies and 43 dwarf galaxies.\nPublished Spitzer/IRS and Herschel/SPIRE line fluxes are included to extend our\ndatabase to the full 10-600 $\\mu m$ spectral range. The observations are\ncompared to a set of CLOUDY photoionisation models to estimate the above\nphysical quantities through different diagnostic diagrams. We confirm the\npresence of a stratification of gas density in the emission regions of the\ngalaxies, which increases with the ionisation potential of the emission lines.\nThe new [OIV]25.9$\\mu m$/[OIII]88$\\mu m$ vs [NeIII]15.6$\\mu m$/[NeII]12.8$\\mu\nm$ diagram is proposed as the best diagnostic to separate: $i)$ AGN activity\nfrom any kind of star formation; and $ii)$ low-metallicity dwarf galaxies from\nstarburst galaxies. Current stellar atmosphere models fail to reproduce the\nobserved [OIV]25.9$\\mu m$/[OIII]88$\\mu m$ ratios, which are much higher when\ncompared to the predicted values. Finally, the ([NeIII]15.6$\\mu m$ +\n[NeII]12.8$\\mu m$)/([SIV]10.5$\\mu m$ + [SIII]18.7$\\mu m$) ratio is proposed as\na promising metallicity tracer to be used in obscured objects, where optical\nlines fail to accurately measure the metallicity. The diagnostic power of mid-\nto far-infrared spectroscopy shown here for local galaxies will be of crucial\nimportance to study galaxy evolution during the dust-obscured phase at the peak\nof the star formation and black-hole accretion activity ($1 < z < 4$). This\nstudy will be addressed by future deep spectroscopic surveys with present and\nforthcoming facilities such as JWST, ALMA, and SPICA.", "positive": "How are Lyman $\u03b1$ absorbers in the cosmic web related to gas-rich\n galaxies?: We present the two-point cross-correlation function between Lyman $\\alpha$\nabsorbers and HI galaxies in the nearby Universe ($0.01 \\le z \\le 0.057$). We\nuse absorbers from 21 QSO sightlines from the Survey of the Low-Redshift\nIntergalactic Medium with HST/COS and the galaxy catalogs from the Arecibo\nLegacy Fast ALFA survey and the New York University Value-Added Galaxy Catalog.\nWe find that Lyman $\\alpha$ absorbers are strongly correlated to Lyman $\\alpha$\ngalaxies at a projected separation of $\\le$0.5 Mpc and velocity separation of\n$\\le 50~km~s^{-1}$. Lyman $\\alpha$ absorbers are 7.6 times more likely to be\nfound near HI galaxies compared to a random distribution. The correlation\ndecreases as the projected and/or velocity separation increase. We also find\nthe correlation between Lyman $\\alpha$ absorbers and HI galaxies to be stronger\nthan those observed between Lyman $\\alpha$ absorbers and optically selected\ngalaxies. There is an enhancement in the number of absorbers at velocity\nseparations of $\\le30~km~s^{-1}$ from HI galaxies at distances larger than\ntheir viral radius. Combined with the fact that most of our galaxies are not\ndriving strong outflows, we conclude that the absorbers at low-velocity\nseparations are tracing cooler intergalactic gas around galaxies. This\nconclusion is consistent with the predictions from cosmological simulations\nwhere faint gas from the intergalactic medium flows into the disks of galaxies\nleading to galaxy growth." }, { "anchor": "UCLCHEMCMC: A MCMC Inference tool for Physical Parameters of Molecular\n Clouds: We present the publicly available, open source code UCLCHEMCMC, designed to\nestimate physical parameters of an observed cloud of gas by combining Monte\nCarlo Markov Chain (MCMC) sampling with chemical and radiative transfer\nmodeling. When given the observed values of different emission lines,\nUCLCHEMCMC runs a Bayesian parameter inference, using a MCMC algorithm to\nsample the likelihood and produce an estimate of the posterior probability\ndistribution of the parameters. UCLCHEMCMC takes a full forward modeling\napproach, generating model observables from the physical parameters via\nchemical and radiative transfer modeling. While running UCLCHEMCMC, the created\nchemical models and radiative transfer code results are stored in an SQL\ndatabase, preventing redundant model calculations in future inferences. This\nmeans that the more UCLCHEMCMC is used, the more efficient it becomes. Using\nUCLCHEM and RADEX, the increase of efficiency is nearly two orders of\nmagnitude, going from 5185.33 \\pm 1041.96 s for ten walkers to take one\nthousand steps when the database is empty, to 68.89 \\pm 45.39 s when nearly all\nmodels requested are in the database. In order to demonstrate its usefulness we\nprovide an example inference of UCLCHEMCMC to estimate the physical parameters\nof mock data, and perform two inferences on the well studied prestellar core,\nL1544, one of which show that it is important to consider the substructures of\nan object when determining which emission lines to use.", "positive": "New metallicity calibration for Seyfert 2 galaxies based on the N2O2\n index: We derive a new relation between the metallicity of Seyfert 2 Active Galactic\nNuclei (AGNs) and the intensity of the narrow emission-lines ratio\n$N2O2$=log([N II]$\\lambda$6584/[O II]$\\lambda$3727). The calibration of this\nrelation was performed determining the metallicity ($Z$) of a sample of 58 AGNs\nthrough a diagram containing the observational data and the results of a grid\nof photoionization models obtained with the Cloudy code. We find the new\n$Z/Z_\\odot$-$N2O2$ relation using the obtained metallicity values and the\ncorresponding observational emission line intensities for each object of the\nsample. Estimations derived through the use of this new calibration indicate\nthat narrow line regions of Seyfert 2 galaxies exhibit a large range of\nmetallicities ($0.3 \\: < \\: Z/Z_{\\odot} \\: < \\:2.0$), with a median value $Z\n\\approx Z_{\\odot}$. Regarding the possible existence of correlations between\nthe luminosity $L(\\rm H\\beta$), the electron density, and the color excess\nE(B$-$V) with the metallicity in this kind of objects, we do not find\ncorrelations between them." }, { "anchor": "Galaxy And Mass Assembly (GAMA): The mechanisms for quiescent galaxy\n formation at $z<1$: One key problem in astrophysics is understanding how and why galaxies switch\noff their star formation, building the quiescent population that we observe in\nthe local Universe. From the GAMA and VIPERS surveys, we use spectroscopic\nindices to select quiescent and candidate transition galaxies. We identify\npotentially rapidly transitioning post-starburst galaxies, and slower\ntransitioning green-valley galaxies. Over the last 8 Gyrs the quiescent\npopulation has grown more slowly in number density at high masses\n(M$_*>10^{11}$M$_\\odot$) than at intermediate masses\n(M$_*>10^{10.6}$M$_\\odot$). There is evolution in both the post-starburst and\ngreen valley stellar mass functions, consistent with higher mass galaxies\nquenching at earlier cosmic times. At intermediate masses\n(M$_*>10^{10.6}$M$_\\odot$) we find a green valley transition timescale of 2.6\nGyr. Alternatively, at $z\\sim0.7$ the entire growth rate could be explained by\nfast-quenching post-starburst galaxies, with a visibility timescale of 0.5 Gyr.\nAt lower redshift, the number density of post-starbursts is so low that an\nunphysically short visibility window would be required for them to contribute\nsignificantly to the quiescent population growth. The importance of the\nfast-quenching route may rapidly diminish at $z<1$. However, at high masses\n(M$_*>10^{11}$M$_\\odot$), there is tension between the large number of\ncandidate transition galaxies compared to the slow growth of the quiescent\npopulation. This could be resolved if not all high mass post-starburst and\ngreen-valley galaxies are transitioning from star-forming to quiescent, for\nexample if they rejuvenate out of the quiescent population following the\naccretion of gas and triggering of star formation, or if they fail to\ncompletely quench their star formation.", "positive": "RadioAstron reveals a spine-sheath jet structure in 3C 273: We present Space-VLBI RadioAstron observations at 1.6 GHz and 4.8 GHz of the\nflat spectrum radio quasar 3C 273, with detections on baselines up to 4.5 and\n3.3 Earth Diameters, respectively. Achieving the best angular resolution at 1.6\nGHz to date, we have imaged limb-brightening in the jet, not previously\ndetected in this source. In contrast, at 4.8 GHz, we detected emission from a\ncentral stream of plasma, with a spatial distribution complementary to the\nlimb-brightened emission, indicating an origin in the spine of the jet. While a\nstratification across the jet width in the flow density, internal energy,\nmagnetic field, or bulk flow velocity are usually invoked to explain the\nlimb-brightening, the different jet structure detected at the two frequencies\nprobably requires a stratification in the emitting electron energy\ndistribution. Future dedicated numerical simulations will allow the\ndetermination of which combination of physical parameters are needed to\nreproduce the spine/sheath structure observed by Space-VLBI with RadioAstron in\n3C 273" }, { "anchor": "The Role of Radiolysis in the Modelling of C$_{2}$H$_{4}$O$_{2}$ Isomers\n and Dimethyl Ether in Cold Dark Clouds: Complex organic molecules (COMs) have been detected in a variety of\ninterstellar sources. The abundances of these COMs in warming sources can be\nexplained by syntheses linked to increasing temperatures and densities,\nallowing quasi-thermal chemical reactions to occur rapidly enough to produce\nobservable amounts of COMs, both in the gas phase, and upon dust grain ice\nmantles. The COMs produced on grains then become gaseous as the temperature\nincreases sufficiently to allow their thermal desorption. The recent\nobservation of gaseous COMs in cold sources has not been fully explained by\nthese gas-phase and dust grain production routes. Radiolysis chemistry is a\npossible non-thermal method of producing COMs in cold dark clouds. This new\nmethod greatly increases the modeled abundance of selected COMs upon the ice\nsurface and within the ice mantle due to excitation and ionization events from\ncosmic ray bombardment. We examine the effect of radiolysis on three\nC$_{2}$H$_{4}$O$_{2}$ isomers -- methyl formate (HCOOCH$_3$), glycolaldehyde\n(HCOCH$_2$OH), and acetic acid (CH$_3$COOH) -- and a chemically similar\nmolecule, dimethyl ether (CH$_3$OCH$_3$), in cold dark clouds. We then compare\nour modelled gaseous abundances with observed abundances in TMC-1, L1689B, and\nB1-b.", "positive": "Molecular gas in three z~7 quasar host galaxies: We present ALMA band 3 observations of the CO(6-5), CO(7-6), and [CI]\n369micron emission lines in three of the highest redshift quasar host galaxies\nat 6.62\", or >14kpc) CO emission in all\nthree quasar hosts. In two sources, we detect the continuum emission around\n400micron (rest-frame), and in one source we detect [CI] at low significance.\nWe derive molecular gas reservoirs of (1-3)x10^10 M_sun in the quasar hosts,\ni.e. approximately only 10 times the mass of their central supermassive black\nholes. The extrapolated [CII]-to-CO(1-0) luminosity ratio is 2500-4200,\nconsistent with measurements in galaxies at lower redshift. The detection of\nthe [CI] line in one quasar host galaxy and the limit on the [CI] emission in\nthe other two hosts enables a first characterization of the physical properties\nof the interstellar medium in z~7 quasar hosts. In the sources, the derived\nglobal CO/[CII]/[CI] line ratios are consistent with expectations from\nphotodissociation regions (PDR), but not X-ray dominated regions (XDR). This\nsuggest that quantities derived from the molecular gas and dust emission are\nrelated to ongoing star-formation activity in the quasar hosts, providing\nfurther evidence that the quasar hosts studied here harbor intense starbursts\nin addition to their active nucleus." }, { "anchor": "The Extreme Red Excess in Blazar Ultraviolet Broad Emission Lines: We present a study of quasars with very redward asymmetric (RA) ultraviolet\n(UV) broad emission lines (BELs). An excess of redshifted emission has been\npreviously shown to occur in the BELs of radio loud quasars and is most extreme\nin certain blazars. Paradoxically, blazars are objects that are characterized\nby a highly relativistic blue-shifted outflow towards Earth. We show that the\nred emitting gas resides in a very broad component (VBC) that is typical of\nPopulation B quasars that are defined by a wide H$\\beta$ BEL profile.\nEmpirically, we find that RA BEL blazars have both low Eddington rates\n($\\lesssim1\\%$) and an inordinately large (order unity) ratio of long term time\naveraged jet power to accretion luminosity. The latter circumstance has been\npreviously shown to be associated with a depressed extreme UV ionizing\ncontinuum. Both properties conspire to produce a low flux of ionizing photons,\ntwo orders of magnitude less than typical Population B quasars. We use CLOUDY\nmodels to demonstrate that a weak ionizing flux is required for gas near the\ncentral black hole to be optimally ionized to radiate BELs with high efficiency\n(most quasars over-ionize nearby gas, resulting in low radiative efficiency).\nThe large gravitational redshift and transverse Doppler shift results in a VBC\nthat is redshifted by $\\sim 2000 -5000$~km~s$^{-1}$ with a correspondingly\nlarge line width. The RA BELs result from an enhanced efficiency (relative to\ntypical Population B quasars) to produce a luminous, redshifted VBC near the\ncentral black hole.", "positive": "MOCCA Survey Database I. BHs in star clusters: We briefly describe and discuss the set-up of the project MOCCA Survey\nDatabase I. The database contains more than 2000 Monte Carlo models of\nevolution of real star cluster performed with the MOCCA code. Then, we very\nbriefly discuss results of analysis of the database regarding the following\nprojects: formation of intermediate mass black holes, abrupt cluster\ndissolution harboring black hole subsystems, retention fraction of black hole -\nblack hole mergers, and tidal disruption events with intermediate mass black\nholes." }, { "anchor": "Inferences on the Relations Between Central Black Hole Mass and Total\n Galaxy Stellar Mass in the high-redshift Universe: At the highest redshifts, z>6, several tens of luminous quasars have been\ndetected. The search for fainter AGN, in deep X-ray surveys, has proven less\nsuccessful, with few candidates to date. An extrapolation of the relationship\nbetween black hole (BH) and bulge mass would predict that the sample of z>6\ngalaxies host relatively massive BHs (>1e6 Msun), if one assumes that total\nstellar mass is a good proxy for bulge mass. At least a few of these BHs should\nbe luminous enough to be detectable in the 4Ms CDFS. The relation between BH\nand stellar mass defined by local moderate-luminosity AGN in low-mass galaxies,\nhowever, has a normalization that is lower by approximately an order of\nmagnitude compared to the BH-bulge mass relation. We explore how this scaling\nchanges the interpretation of AGN in the high-z Universe. Despite large\nuncertainties, driven by those in the stellar mass function, and in the\nextrapolation of local relations, one can explain the current non-detection of\nmoderate-luminosity AGN in Lyman Break Galaxies if galaxies below 1e11 Msun are\ncharacterized by the low-normalization scaling, and, even more so, if their\nEddington ratio is also typical of moderate-luminosity AGN rather than luminous\nquasars. AGN being missed by X-ray searches due to obscuration or instrinsic\nX-ray weakness also remain a possibility.", "positive": "PAGaN I: Multi-Frequency Polarimetry of AGN Jets with KVN: Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to\nstudy the structure of and physical conditions in relativistic outflows. For\nsuch studies, multi-frequency polarimetric very long baseline interferometric\n(VLBI) observations are important as they directly probe particle densities,\nmagnetic field geometries, and several other parameters. We present results\nfrom first-epoch data obtained by the Korean VLBI Network (KVN) within the\nframe of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We\nobserved seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129\nGHz in dual polarization mode. Our observations constrain apparent brightness\ntemperatures of jet components and radio cores in our sample to $>10^{8.01}$ K\nand $>10^{9.86}$ K, respectively. Degrees of linear polarization $m_{L}$ are\nrelatively low overall: less than 10%. This indicates suppression of\npolarization by strong turbulence in the jets. We found an exceptionally high\ndegree of polarization in a jet component of BL Lac at 43 GHz, with $m_{L}\n\\sim$ 40%. Assuming a transverse shock front propagating downstream along the\njet, the shock front being almost parallel to the line of sight can explain the\nhigh degree of polarization." }, { "anchor": "Numerical Simulation and Completeness Survey of Bubbles in the Taurus\n and Perseus Molecular Clouds: Previous studies have analyzed the energy injection into the interstellar\nmatter due to molecular bubbles. They found that the total kinetic energies of\nbubbles are comparable to, or even larger than, those of outflows but still\nless than the gravitational potential and turbulence energies of the hosting\nclouds. We examined the possibility that previous studies underestimated the\nenergy injection due to being unable to detect dim or incomplete bubbles. We\nsimulated typical molecular bubbles and inserted them into the $^{13}$CO Five\nCollege Radio Astronomical Observatory maps of the Taurus and Perseus Molecular\nClouds. We determined bubble identification completeness by applying the same\nprocedures to both simulated and real data sets. We proposed a detectability\nfunction for both the Taurus and Perseus molecular clouds based on a\nmultivariate approach. In Taurus, bubbles with kinetic energy less than ~$1\n\\times 10^{44}$ erg are likely to be missed. We found that the total missing\nkinetic energy in Taurus is less than a couple of $10^{44}$ erg, which only\naccounts for around 0.2% of the total kinetic energy of identified bubbles. In\nPerseus, bubbles with kinetic energy less than ~$2 \\times 10^{44}$ erg are\nlikely to be missed. We found that the total missing kinetic energy in Perseus\nis less than $10^{45}$ erg, which only accounts for around 1% of the total\nkinetic energy of identified bubbles. We thus conclude that previous manual\nbubble identification routines used in Taurus and Perseus can be considered to\nbe energetically complete. Therefore, we confirm that energy injection from\ndynamic structures, namely outflows and bubbles, produced by star formation\nfeedback are sufficient to sustain turbulence at a spatial scale from ~0.1 to\n~2.8 pc.", "positive": "The magnetic field of molecular clouds: The magnetic field of molecular clouds (MCs) plays an important role in the\nprocess of star formation: it determins the statistical properties of\nsupersonic turbulence that controls the fragmentation of MCs, controls the\nangular momentum transport during the protostellar collapse, and affects the\nstability of circumstellar disks. In this work, we focus on the problem of the\ndetermination of the magnetic field strength. We review the idea that the MC\nturbulence is super-Alfv\\'{e}nic, and we argue that MCs are bound to be born\nsuper-Alfv\\'{e}nic. We show that this scenario is supported by results from a\nrecent simulation of supernova-driven turbulence on a scale of 250 pc, where\nthe turbulent cascade is resolved on a wide range of scales, including the\ninterior of MCs." }, { "anchor": "The galaxy starburst/main-sequence bimodality over five decades in\n stellar mass at z ~ 3-6.5: We study the relation between stellar mass (M*) and star formation rate (SFR)\nfor star-forming galaxies over approximately five decades in stellar mass (5.5\n<~ log10(M*/Msun) <~ 10.5) at z ~ 3-6.5. This unprecedented coverage has been\npossible thanks to the joint analysis of blank non-lensed fields (COSMOS/SMUVS)\nand cluster lensing fields (Hubble Frontier Fields) which allow us to reach\nvery low stellar masses. Previous works have revealed the existence of a clear\nbimodality in the SFR-M* plane with a star-formation Main Sequence and a\nstarburst cloud at z ~ 4-5. Here we show that this bimodality extends to all\nstar-forming galaxies and is valid in the whole redshift range z ~ 3-6.5. We\nfind that starbursts constitute at least 20% of all star-forming galaxies with\nM* >~ 10^9 Msun at these redshifts and reach a peak of 40% at z=4-5. More\nimportantly, 60% to 90% of the total SFR budget at these redshifts is contained\nin starburst galaxies, indicating that the starburst mode of star-formation is\ndominant at high redshifts. Almost all the low stellar-mass starbursts with\nlog10(M*/Msun) <~ 8.5 have ages comparable to the typical timescales of a\nstarburst event, suggesting that these galaxies are being caught in the process\nof formation. Interestingly, galaxy formation models fail to predict the\nstarburst/main-sequence bimodality and starbursts overall, suggesting that the\nstarburst phenomenon may be driven by physical processes occurring at smaller\nscales than those probed by these models.", "positive": "An improved map of the Galactic Faraday sky: We aim to summarize the current state of knowledge regarding Galactic Faraday\nrotation in an all-sky map of the Galactic Faraday depth. For this we have\nassembled the most extensive catalog of Faraday rotation data of compact\nextragalactic polarized radio sources to date. In the map making procedure we\nuse a recently developed algorithm that reconstructs the map and the power\nspectrum of a statistically isotropic and homogeneous field while taking into\naccount uncertainties in the noise statistics. This procedure is able to\nidentify some rotation angles that are offset by an integer multiple of pi. The\nresulting map can be seen as an improved version of earlier such maps and is\nmade publicly available, along with a map of its uncertainty. For the angular\npower spectrum we find a power law behavior with a power law index of -2.14 for\na Faraday sky where an overall variance profile as a function of Galactic\nlatitude has been removed, in agreement with earlier work. We show that this is\nin accordance with a 3D Fourier power spectrum P(k) proportional to k^-2.14 of\nthe underlying field n_e times B_r under simplifying geometrical and\nstatistical assumptions." }, { "anchor": "Transformations between WISE, 2MASS, SDSS and BVRI photometric systems:\n I. Transformation equations for dwarfs: We present colour transformations for the conversion of the W1 and W2\nmagnitudes of WISE photometric system to the Johnson-Cousins' BVRI, SDSS (gri),\nand 2MASS (JHK_s) photometric systems, for dwarfs. The W3 and W4 magnitudes\nwere not considered due to their insufficient signal to noise ratio (S/N). The\ncoordinates of 825 dwarfs along with their BVRI, gri, and JHK_s data, taken\nfrom Bilir et al. (2008) were matched with the coordinates of stars in the\npreliminary data release of WISE (Wright et al., 2010) and a homogeneous dwarf\nsample with high S/N ratio have been obtained using the following constraints:\n1) the data were dereddened, 2) giants were identified and excluded from the\nsample, 3) sample stars were selected according to data quality, 4)\ntransformations were derived for sub samples of different metallicity range,\nand 5) transformations are two colour dependent. These colour transformations,\ncoupled with known absolute magnitudes at shorter wavelenghts, can be used in\nspace density evaluation for the Galactic (thin and thick) discs, at distances\nlarger than the ones evaluated with JHK_s photometry.", "positive": "Galactic Warps in Triaxial Halos: We study the behaviors of galactic disks in triaxial halos both numerically\nand analytically to see if warps can be excited and sustained in triaxial\npotentials. We consider the following two scenarios: 1) galactic disks that are\ninitially tilted relative to the equatorial plane of the halo (for a\npedagogical purpose), and 2) tilted infall of dark matter relative to the\nequatorial plane of the disk and the halo. With numerical simulations of\n100,000 disk particles in a fixed halo potential, we find that in triaxial\nhalos, warps can be excited and sustained just as in spherical or axisymmetric\nhalos but they show some oscillatory behaviors and even can be transformed to a\npolar-ring system if the halo has a prolate-like triaxiality. The\nnon-axisymmetric component of the halo causes the disk to nutate, and the\ndifferential nutation between the inner and outer parts of the disk generally\nmakes the magnitude of the warp slightly diminish and fluctuate. We also find\nthat warps are relatively weaker in oblate and oblate-like triaxial halos, and\nsince these halos are the halo configurations of disk galaxies inferred by\ncosmological simulations, our results are consistent with the fact that most of\nthe observed warps are quite weak. We derive approximate formulae for the\ntorques exerted on the disk by the triaxial halo and the dark matter torus, and\nwith these formulae we successfully describe the behaviors of the disks in our\nsimulations. The techniques used in deriving these formulae could be applied\nfor realistic halos with more complex structures." }, { "anchor": "Rotation of molecular clouds in M~51: The grand-design spiral galaxy M~51 was observed at 40pc resolution in\nCO(1--0) by the PAWS project. A large number of molecular clouds were\nidentified and we search for velocity gradients in two high signal-to-noise\nsubsamples, containing 682 and 376 clouds. The velocity gradients are found to\nbe systematically prograde oriented, as was previously found for the rather\nflocculent spiral M~33. This strongly supports the idea that the velocity\ngradients reflect cloud rotation, rather than more random dynamical forces,\nsuch as turbulence. Not only are the gradients prograde, but their\n$\\frac{\\partial v}{\\partial x}$ and $\\frac{\\partial v}{\\partial y}$\ncoefficients follow galactic shear in sign, although with a lower amplitude. No\nlink is found between the orientation of the gradient and the orientation of\nthe cloud. The values of the cloud angular momenta appear to be an extension of\nthe values noted for galactic clouds despite the orders of magnitude difference\nin cloud mass. Roughly 30\\% of the clouds show retrograde velocity gradients.\nFor a strictly rising rotation curve, as in M~51, gravitational contraction\nwould be expected to yield strictly prograde rotators within an axisymmetric\npotential. In M~51, the fraction of retrograde rotators is found to be higher\nin the spiral arms than in the disk as a whole. Along the leading edge of the\nspiral arms, a majority of the clouds are retrograde rotators. While this work\nshould be continued on other nearby galaxies, the M~33 and M~51 studies have\nshown that clouds rotate and that they rotate mostly prograde, although the\namplitudes are not such that rotational energy is a significant support\nmechanism against gravitation. In this work, we show that retrograde rotation\nis linked to the presence of a spiral gravitational potential.", "positive": "Inferring dark matter halo properties for HI-selected galaxies: We set constraints on the dark matter halo mass and concentration of ~22,000\nindividual galaxies visible both in HI (from the ALFALFA survey) and optical\nlight (from the SDSS). This is achieved by combining two Bayesian models, one\nfor the HI line width as a function of the stellar and neutral hydrogen mass\ndistributions in a galaxy using kinematic modelling, and the other for the\ngalaxy's total baryonic mass using the technique of inverse subhalo abundance\nmatching. We hence quantify the constraining power on halo properties of\nspectroscopic and photometric observations, and assess their consistency. We\nfind good agreement between the two sets of posteriors, although there is a\nsizeable population of low-line width galaxies that favour significantly\nsmaller dynamical masses than expected from abundance matching (especially for\ncuspy halo profiles). Abundance matching provides significantly more stringent\nbounds on halo properties than the HI line width, even with a\nmass--concentration prior included, although combining the two provides a mean\ngain of 40% for the sample when fitting an NFW profile. We also use our\nkinematic posteriors to construct a baryonic mass--halo mass relation, which we\nfind to be near power-law, and with a somewhat shallower slope than expected\nfrom abundance matching. Our method demonstrates the potential of combining\nphotometric and spectroscopic observations to precisely map out the dark matter\ndistribution at the galaxy scale using upcoming HI surveys such as the SKA." }, { "anchor": "KMOS^3D: Dynamical constraints on the mass budget in early star-forming\n disks: We exploit deep integral-field spectroscopic observations with KMOS/VLT of\n240 star-forming disks at 0.6 < z < 2.6 to dynamically constrain their mass\nbudget. Our sample consists of massive ($\\gtrsim 10^{9.8} M_\\odot$) galaxies\nwith sizes $R_e \\gtrsim 2$ kpc. By contrasting the observed velocity and\ndispersion profiles to dynamical models, we find that on average the stellar\ncontent contributes $32^{+8}_{-7}\\%$ of the total dynamical mass, with a\nsignificant spread among galaxies (68th percentile range f_star ~ 18 - 62%).\nIncluding molecular gas as inferred from CO- and dust-based scaling relations,\nthe estimated baryonic mass adds up to $56^{+17}_{-12}\\%$ of total for the\ntypical galaxy in our sample, reaching ~ 90% at z > 2. We conclude that baryons\nmake up most of the mass within the disk regions of high-redshift star-forming\ndisk galaxies, with typical disks at z > 2 being strongly baryon-dominated\nwithin $R_e$. Substantial object-to-object variations in both stellar and\nbaryonic mass fractions are observed among the galaxies in our sample, larger\nthan what can be accounted for by the formal uncertainties in their respective\nmeasurements. In both cases, the mass fractions correlate most strongly with\nmeasures of surface density. High $\\Sigma_{star}$ galaxies feature stellar mass\nfractions closer to unity, and systems with high inferred gas or baryonic\nsurface densities leave less room for additional mass components other than\nstars and molecular gas. Our findings can be interpreted as more extended disks\nprobing further (and more compact disks probing less far) into the dark matter\nhalos that host them.", "positive": "ALMA Observations of Circumnuclear Disks in Early Type Galaxies:\n 12CO(2-1) and Continuum Properties: We present results from an Atacama Large Millimeter/submillimeter Array\n(ALMA) Cycle 2 program to map CO(2-1) emission in nearby early-type galaxies\n(ETGs) that host circumnuclear gas disks. We obtained $\\sim0.3''-$resolution\nBand 6 observations of seven ETGs selected on the basis of dust disks in Hubble\nSpace Telescope images. We detect CO emission in five at high signal-to-noise\nratio with the remaining two only faintly detected. All CO emission is\ncoincident with the dust and is in dynamically cold rotation. Four ETGs show\nevidence of rapid central rotation; these are prime candidates for\nhigher-resolution ALMA observations to measure the black hole masses. In this\npaper we focus on the molecular gas and continuum properties. Total gas masses\nand H$_2$ column densities for our five CO-bright galaxies are on average\n$\\sim10^8$ $M_\\odot$ and $\\sim10^{22.5}$ cm$^{-2}$ over the $\\sim$kpc-scale\ndisks, and analysis suggests that these disks are stabilized against\ngravitational fragmentation. The continuum emission of all seven galaxies is\ndominated by a central, unresolved source, and in five we also detect a\nspatially extended component. The $\\sim$230 GHz nuclear continua are modeled as\npower laws ranging from $S_\\nu \\sim \\nu^{-0.4}$ to $\\nu^{1.6}$ within the\nobserved frequency band. The extended continuum profiles of the two\nradio-bright (and CO-faint) galaxies are roughly aligned with their radio jet\nand suggests resolved synchrotron jets. The extended continua of the CO-bright\ndisks are coincident with optically thick dust absorption and have spectral\nslopes that are consistent with thermal dust emission." }, { "anchor": "Laboratory Experiments, Numerical Simulations, and Astronomical\n Observations of Deflected Supersonic Jets: Application to HH 110: Collimated supersonic flows in laboratory experiments behave in a similar\nmanner to astrophysical jets provided that radiation, viscosity, and thermal\nconductivity are unimportant in the laboratory jets, and that the experimental\nand astrophysical jets share similar dimensionless parameters such as the Mach\nnumber and the ratio of the density between the jet and the ambient medium.\nLaboratory jets can be studied for a variety of initial conditions, arbitrary\nviewing angles, and different times, attributes especially helpful for\ninterpreting astronomical images where the viewing angle and initial conditions\nare fixed and the time domain is limited. Experiments are also a powerful way\nto test numerical fluid codes in a parameter range where the codes must perform\nwell. In this paper we combine images from a series of laboratory experiments\nof deflected supersonic jets with numerical simulations and new spectral\nobservations of an astrophysical example, the young stellar jet HH 110. The\nexperiments provide key insights into how deflected jets evolve in 3-D,\nparticularly within working surfaces where multiple subsonic shells and\nfilaments form, and along the interface where shocked jet material penetrates\ninto and destroys the obstacle along its path. The experiments also underscore\nthe importance of the viewing angle in determining what an observer will see.\nThe simulations match the experiments so well that we can use the simulated\nvelocity maps to compare the dynamics in the experiment with those implied by\nthe astronomical spectra. The experiments support a model where the observed\nshock structures in HH 110 form as a result of a pulsed driving source rather\nthan from weak shocks that may arise in the supersonic shear layer between the\nMach disk and bow shock of the jet's working surface.", "positive": "Merger-Induced Metallicity Dilution in Cosmological Galaxy Formation\n Simulations: Observational studies have revealed that galaxy pairs tend to have lower\ngas-phase metallicity than isolated galaxies. This metallicity deficiency can\nbe caused by inflows of low-metallicity gas due to the tidal forces and\ngravitational torques associated with galaxy mergers, diluting the metal\ncontent of the central region. In this work we demonstrate that such\nmetallicity dilution occurs in state-of-the-art cosmological simulations of\ngalaxy formation. We find that the dilution is typically 0.1 dex for major\nmergers, and is noticeable at projected separations smaller than $40$ kpc. For\nminor mergers the metallicity dilution is still present, even though the\namplitude is significantly smaller. Consistent with previous analysis of\nobserved galaxies we find that mergers are outliers from the \\emph{fundamental\nmetallicity relation}, with deviations being larger than expected for a\nGaussian distribution of residuals. Our large sample of mergers within full\ncosmological simulations also makes it possible to estimate how the star\nformation rate enhancement and gas consumption timescale behave as a function\nof the merger mass ratio. We confirm that strong starbursts are likely to occur\nin major mergers, but they can also arise in minor mergers if more than two\ngalaxies are participating in the interaction, a scenario that has largely been\nignored in previous work based on idealised isolated merger simulations." }, { "anchor": "Globular cluster candidates in the Galactic bulge: Gaia and VVV view of\n the latest discoveries: Thanks to the recent wide-area photometric surveys, the number of star\ncluster candidates have risen exponentially in the last few years. Most\ndetections, however, are based only on the presence of an overdensity of stars\nin a given region, or an overdensity of variable stars, regardless of their\ndistance. As candidates, their detection has not been dynamically confirmed.\nTherefore, it is currently unknown how many, and which ones, of the published\ncandidates, are true clusters, and which ones are chance alignments. We present\na method to detect and confirm star clusters based on the spatial distribution,\ncoherence in motion and appearance on the color-magnitude diagram. We explain\nand apply it to one new star cluster, and several candidate star clusters\npublished in the literature. The presented method is based on data from the\nSecond Data Release of Gaia complemented with data from the VISTA Variables in\nthe V\\'ia L\\'actea survey for the innermost bulge regions. It consists of a\nnearest neighbors algorithm applied simultaneously over spatial coordinates,\nstar color, and proper motions, in order to detect groups of stars that are\nclose in the sky, move coherently and define narrow sequences in the\ncolor-magnitude diagram, such as a young main sequence or a red giant branch.\nWhen tested in the bulge area ($-10<\\ell\\ {\\rm (deg)}<+10$; $-103\\times10^{47}$ erg/s) from the WISSH sample at\nz~2.4-4.7. We report a 100% emission line detection rate and a 80% detection\nrate in continuum emission, and we find CO emission to be consistent with the\nsteepest CO ladders observed so far. Sub-mm data reveal presence of (one or\nmore) bright companion galaxies around 80% of WISSH QSOs, at projected\ndistances of 6-130 kpc. We observe a variety of sizes for the molecular gas\nreservoirs (1.7-10 kpc), associated with rotating disks with disturbed\nkinematics. WISSH QSOs typically show lower CO luminosity and higher star\nformation efficiency than FIR matched, z~0-3 main-sequence galaxies, implying\nthat, given the observed SFR ~170-1100 $M_\\odot$/yr, molecular gas is converted\ninto stars on <50 Myr. Most targets show extreme dynamical to black-hole mass\nratios $M_{\\rm dyn}/M_{\\rm BH}\\sim3-10$, two orders of magnitude smaller than\nlocal relations. The molecular gas fraction in WISSH hosts is lower by a factor\nof ~10-100 than in star forming galaxies with similar $M_*$. WISSH QSOs undergo\nan intense growth phase of both the central SMBH and host-galaxy. They pinpoint\nhigh-density sites where giant galaxies assemble and mergers play a major role\nin the build-up of the final host-galaxy mass. The observed low molecular gas\nfraction and short depletion timescale are likely due to AGN feedback, as\ntraced by fast AGN-driven ionised outflows in all our targets.", "positive": "The HerMES sub-millimetre local and low-redshift luminosity functions: We used wide area surveys over 39 deg$^2$ by the HerMES collaboration,\nperformed with the Herschel Observatory SPIRE multi-wavelength camera, to\nestimate the low-redshift, $0.0210^{11.0}\\,\\mathrm{M}_{\\odot}$). Hence, the X-IFU will\nprobe covering fractions comparable to those detected with the Cosmic Origins\nSpectrograph for O VI." }, { "anchor": "In search of infall motion in molecular clumps III: HCO+ (1-0) and\n H13CO+ (1-0) mapping observations toward the confirmed infall sources: The study of infall motion helps us to understand the initial stages of star\nformation. In this paper, we use the IRAM 30-m telescope to make mapping\nobservations of 24 infall sources confirmed in previous work. The lines we use\nto track gas infall motions are HCO+ (1-0) and H13CO+ (1-0). All 24 sources\nshow HCO+ emissions, while 18 sources show H13CO+ emissions. The HCO+\nintegrated intensity maps of 17 sources show clear clumpy structures; for the\nH13CO+ line, 15 sources show clumpy structures. We estimated the column density\nof HCO+ and H13CO+ using the RADEX radiation transfer code, and the obtained\n[HCO+]/[H2] and [H13CO+]/[HCO+] of these sources are about 10^-11 ~ 10^-7 and\n10^-3~1, respectively. Based on the asymmetry of the line profile of the HCO+,\nwe distinguish these sources: 19 sources show blue asymmetric profiles, and the\nother sources show red profiles or symmetric peak profiles. For eight sources\nthat have double-peaked blue line profiles and signal-to-noise ratios greater\nthan 10, the RATRAN model is used to fit their HCO^+ (1-0) lines, and to\nestimate their infall parameters. The mean Vin of these sources are 0.3 ~ 1.3\nkm/s, and the Min are about 10^-3 ~ 10^-4 Msun/yr , which are consistent with\nthe results of intermediate or massive star formation in previous studies. The\nVin estimated from the Myers model are 0.1 ~ 1.6 km/s, and the Min are within\n10^-3 ~ 10^-5 Msun/yr. In addition, some identified infall sources show other\nstar-forming activities, such as outflows and maser emissions. Especially for\nthose sources with a double-peaked blue asymmetric profile, most of them have\nboth infall and outflow evidence.", "positive": "ARGOS III: Stellar Populations in the Galactic Bulge of the Milky Way: We present the metallicity results from the ARGOS spectroscopic survey of the\nGalactic bulge. Our aim is to understand the formation of the Galactic bulge:\ndid it form via mergers, as expected from Lambda CDM theory, or from disk\ninstabilities, as suggested by its boxy/peanut shape, or both? We have obtained\nspectra for 28,000 stars at a spectral resolution of R = 11,000. From these\nspectra, we have determined stellar parameters and distances to an accuracy of\n< 1.5 kpc. The stars in the inner Galaxy span a large range in [Fe/H], -2.8 <\n[Fe/H] < +0.6. From the spatial distribution of the red clump stars as a\nfunction of [Fe/H] (Ness et al. 2012a), we propose that the stars with [Fe/H] >\n-0.5 are part of the boxy/peanut bar/bulge. We associate the lower metallicity\nstars ([Fe/H] < -0.5) with the thick disk, which may be puffed up in the inner\nregion, and with the inner regions of the metal-weak thick disk and inner halo.\nFor the bulge stars with [Fe/H] > -0.5, we find two discrete populations; (i)\nstars with [Fe/H] ~ -0.25 which provide a roughly constant fraction of the\nstars in the latitude interval b = -5 deg to -10 deg, and (ii) a kinematically\ncolder, more metal-rich population with mean [Fe/H] ~ +0.15 which is more\nprominent closer to the plane. The changing ratio of these components with\nlatitude appears as a vertical abundance gradient of the bulge. We attribute\nboth of these bulge components to instability-driven bar/bulge formation from\nthe thin disk. We do not exclude a weak underlying classical merger-generated\nbulge component, but see no obvious kinematic association of any of our bulge\nstars with such a classical bulge component. [abridged]" }, { "anchor": "Quenching and ram pressure stripping of simulated Milky Way satellite\n galaxies: We present predictions for the quenching of star formation in satellite\ngalaxies of the Local Group from a suite of 30 cosmological zoom simulations of\nMilky Way-like host galaxies. The Auriga simulations resolve satellites down to\nthe luminosity of the classical dwarf spheroidal galaxies of the Milky Way. We\nfind strong mass-dependent and distance-dependent quenching signals, where\ndwarf systems beyond 600 kpc are only strongly quenched below a stellar mass of\n$10^7$ M$_\\odot$. Ram pressure stripping appears to be the dominant quenching\nmechanism and 50% of quenched systems cease star formation within 1 Gyr of\nfirst infall. We demonstrate that systems within a host galaxy's $R_{200}$\nradius are comprised of two populations: (i) a first infall population that has\nentered the host halo within the past few Gyrs and (ii) a population of\nreturning `backsplash' systems that have had a much more extended interaction\nwith the host. Backsplash galaxies that do not return to the host galaxy by\nredshift zero exhibit quenching properties similar to galaxies within $R_{200}$\nand are distinct from other external systems. The simulated quenching trend\nwith stellar mass has some tension with observations, but our simulations are\nable reproduce the range of quenching times measured from resolved stellar\npopulations of Local Group dwarf galaxies.", "positive": "What determines the HI gas content in galaxies?: morphological\n dependence of the HI gas fraction across M*-SFR plane: We perform a stacking analysis of the HI spectra from the Arecibo Legacy Fast\nALFA (ALFALFA) survey for optically-selected local galaxies from the Sloan\nDigital Sky Survey (SDSS) to study the average gas fraction of galaxies at\nfixed stellar mass ($M_*$) and star formation rate (SFR). We first confirm that\nthe average gas fraction strongly depends on the stellar mass and SFR of host\ngalaxies; massive galaxies tend to have a lower gas fraction, and actively\nstar-forming galaxies show higher gas fraction, which is consistent with many\nprevious studies. Then we investigate the morphological dependence of the HI\ngas mass fraction at fixed $M_*$ and SFR to minimize the effects of these\nparameters. We use three morphological classifications based on parametric\nindicator (S\\'{e}rsic index), non-parametric indicator (C-index), and visual\ninspection (smoothness from the Galaxy Zoo 2 project) on the optical image. We\nfind that there is no significant morphological dependence of the HI gas mass\nfraction at fixed $M_*$ and SFR when we use C-index. In comparison, there\nexists a hint of diminishment in the HI gas mass fraction for \"smooth\" galaxies\ncompared with \"non-smooth\" galaxies. We find that the visual smoothness is\nsensitive to the existence of small-scale structures in a galaxy. Our result\nsuggests that even at fixed $M_*$ and SFR, the presence of such small-scale\nstructures (seen in the optical image) is linked to their total HI gas content." }, { "anchor": "Direct $N$-body simulations of globular clusters - II. Palomar 4: We use direct $N$-body calculations to study the evolution of the unusually\nextended outer halo globular cluster Palomar 4 (Pal~4) over its entire lifetime\nin order to reproduce its observed mass, half-light radius, velocity dispersion\nand mass function slope at different radii.\n We find that models evolving on circular orbits, and starting from a non-mass\nsegregated, canonical initial mass function (IMF) can reproduce neither Pal 4's\noverall mass function slope nor the observed amount of mass segregation.\nIncluding either primordial mass segregation or initially flattened IMFs does\nnot reproduce the observed amount of mass segregation and mass function\nflattening simultaneously. Unresolved binaries cannot reconcile this\ndiscrepancy either. We find that only models with both a flattened IMF and\nprimordial segregation are able to fit the observations. The initial (i.e.\nafter gas expulsion) mass and half-mass radius of Pal~4 in this case are about\n57000 M${\\odot}$ and 10 pc, respectively. This configuration is more extended\nthan most globular clusters we observe, showing that the conditions under which\nPal~4 formed must have been significantly different from that of the majority\nof globular clusters. We discuss possible scenarios for such an unusual\nconfiguration of Pal~4 in its early years.", "positive": "Trimodal structure of Hercules stream explained by originating from bar\n resonances: Gaia Data Release 2 revealed detailed structures of nearby stars in phase\nspace. These include the Hercules stream, whose origin is still debated. Most\nof the previous numerical studies conjectured that the observed structures\noriginate from orbits in resonance with the bar, based on static potential\nmodels for the Milky Way. We, in contrast, approach the problem via a\nself-consistent, dynamic, and morphologically well-resolved model, namely a\nfull $N$-body simulation of the Milky Way. Our simulation comprises about 5.1\nbillion particles in the galactic stellar bulge, bar, disk, and dark-matter\nhalo and is evolved to 10 Gyr. Our model's disk component is composed of 200\nmillion particles, and its simulation snapshots are stored every 10 Myr,\nenabling us to resolve and classify resonant orbits of representative samples\nof stars. After choosing the Sun's position in the simulation, we compare the\ndistribution of stars in its neighborhood with Gaia's astrometric data, thereby\nestablishing the role of identified resonantly trapped stars in the formation\nof Hercules-like structures. From our orbital spectral-analysis we identify\nmultiple, especially higher order resonances. Our results suggest that the\nHercules stream is dominated by the 4:1 and 5:1 outer Lindblad and corotation\nresonances. In total, this yields a trimodal structure of the Hercules stream.\nFrom the relation between resonances and ridges in phase space, our model\nfavored a slow pattern speed of the Milky-Way bar (40--45 $\\mathrm{km \\; s^{-1}\n\\; kpc^{-1}}$)." }, { "anchor": "Stream Fanning and Bifurcations: Observable Signatures of Resonances in\n Stellar Stream Morphology: Recent observations have revealed a trove of unexpected morphological\nfeatures in many of the Milky Way's stellar streams. Explanations for such\nfeatures include time-dependent deformations of the Galactic gravitational\npotential, local disruptions induced by dark matter substructure, and special\nconfigurations of the streams' progenitors. In this paper, we study how these\nmorphologies can also arise in certain static, non-spherical gravitational\npotentials that host a subset of resonantly-trapped orbit families. The\ntransitions, or separatrices, between these orbit families mark abrupt\ndiscontinuities in the orbital structure of the potential. We develop a novel\nnumerical approach for measuring the libration frequencies of resonant and\nnear-resonant orbits, and apply it to study the evolution of stellar streams on\nthese orbits. We reveal two distinct morphological features that arise in\nstreams on near-resonant orbits: fans, that come about due to a large spread in\nthe libration frequencies near a separatrix; and bifurcations, that arise when\na separatrix splits the orbital distribution of the stellar stream between two\n(or more) distinct orbit families. We demonstrate that these effects can arise\nin some Milky Way streams for certain choices of the dark matter halo\npotential, and discuss how this might be used to probe and constrain the global\nshape of the Milky Way's gravitational potential.", "positive": "Multi-scale simulations of black hole accretion in barred galaxies:\n Self-gravitating disk models: Due to the non-axisymmetric potential of the central bar, barred spiral\ngalaxies form, in addition to their characteristic arms and bar, a variety of\nstructures within the thin gas disk, like nuclear rings, inner spirals and\ndust-lanes. These structures in the inner kiloparsec are most important to\nexplain and understand the rate of black hole feeding. The aim of this work is\nto investigate the influence of stellar bars in spiral galaxies on the thin\nself-gravitating gas disk. We focus on the accretion of gas onto the central\nsupermassive black hole and its time-dependent evolution. We conduct\nmulti-scale simulations simultaneously resolving the galactic disk and the\naccretion disk around the central black-hole. We vary in all simulations the\ninitial gas disk mass. As additional parameter we choose either the gas\ntemperature for isothermal simulations or the cooling timescale in case of\nnon-isothermal simulations. Accretion is either driven by a gravitationally\nunstable or clumpy accretion disk or by energy dissipation in strong shocks.\nMost simulations show a strong dependence of the accretion rate at the outer\nboundary of the central accretion disk ($r< 300~\\mathrm{pc}$) on the gas flow\nat kiloparsec scales. The final black hole masses reach up to $\\sim 10^9\nM_\\odot$ after $1.6~\\mathrm{Gyr}$. Our models show the expected influence of\nthe Eddington limit and a decline in growth rate at the corresponding\nsub-Eddington limit." }, { "anchor": "Testing assumptions and predictions of star-formation theories: (Abridged). We present numerical simulations of isothermal, MHD, supersonic\nturbulence, designed to test various hypotheses frequently assumed in star\nformation(SF) theories. We consider three simulations, each with a different\ncombination of physical size, rms sonic Mach number, and Jeans parameter, but\nchosen as to give the same value of the virial parameter and to conform with\nLarson's scaling relations. As in the non-magnetic case: we find no\nsimultaneously subsonic and super-Jeans structures in our MHD simulations. We\nfind that the fraction of small-scale super-Jeans structures increases when\nself gravity is turned on, and that the production of gravitationally unstable\ndense cores by turbulence alone is very low. This implies that self-gravity is\nin general necessary not only to induce the collapse of Jeans-unstable cores,\nbut also to form them. We find that denser regions tend to have more negative\nvalues of the velocity divergence, implying a net inwards flow towards the\nregions' centers. We compare the results from our simulations with the\npredictions from the recent SF theories by Krumholz & McKee, Padoan & Nordlund,\nand Hennebelle & Chabrier, using the expressions recently provided by Federrath\n& Klessen. We find that none of these theories reproduces the dependence of the\nSFEff with Ms observed in our simulations in the MHD case. The SFEff predicted\nby the theories ranges between half and one order of magnitude larger than what\nwe observe in the simulations in both the HD and the MHD cases. We conclude\nthat the type of flow used in simulations like the ones presented here and\nassumed in recent SF theories, may not correctly represent the flow within\nactual clouds, and that theories that assume it does may be missing a\nfundamental aspect of the flow. We suggest that a more realistic regime may be\nthat of hierarchical gravitational collapse.", "positive": "Gravitational interactions between globular and open clusters: an\n introduction: Historically, it has been assumed that globular and open clusters never\ninteract. However, recent evidence suggests that: globular clusters passing\nthrough the disk may be able to perturb giant molecular clouds (GMCs)\ntriggering formation of open clusters and some old open clusters may be linked\nto accreted globulars. Here, we further explore the existence of possible\ndynamical connections between globular and open clusters, and realize that the\nmost obvious link must be in the form of gravitational interactions. If open\nclusters are born out of GMCs, they have to move in similar orbits. If we\naccept that globulars can interact with GMCs, triggering star formation, it\nfollows that globular and open clusters must also interact. Consistently,\ntheoretical arguments as well as observational evidence, show that globular and\nopen clusters certainly are interacting populations and their interactions are\nfar more common than usually thought, especially for objects part of the\nbulge/disk. Monte Carlo calculations confirm that conclusion. Globular clusters\nseem capable of not only inducing formation of open clusters but, more often,\ntheir demise. Relatively frequent high speed cluster encounters or cluster\nharassment may also cause, on the long-term, slow erosion and tidal truncation\non the globulars involved. The disputed object FSR 1767 (2MASS-GC04) may be,\nstatistically speaking, the best example of an ongoing interaction." }, { "anchor": "Petroleum, coal and other organics in space: The petroleum and coal models of the unidentified infrared emissions (UIE),\nsometimes referred also as unidentified infrared bands (UIBs) has been reviewed\nmainly based on the work of the authors with the inclusion of unpublished\nresults. It is shown that the petroleum and coal model of the UIE converges and\nmerges quite well with the MAON (Mixed Aromatic Aliphatic Organic\nNanoparticles) model of the UIE. It is shown that the thermal treatment of\nvarious substrates like PAHs, alkylated PAHs but also mixed aliphatic/olefinic\nsubstrates leads invariable to carbonaceous materials matching the infrared\nspectrum of anthracite coal or certain petroleum fractions. Thus, the\nexperimental thermal processing (which under space conditions could be\nequivalent to the expected processing by shock waves or high energy radiation)\nof mixed aromatic/aliphatic organic matter can be used to match also the UIE\nevolution. Another way to simulate the thermal/radiation processing of organic\nmatter in space, can be achieved through the carbon arc. Simple substrates\nprocessed in this way produce carbon soot and a plethora of organic molecules.\nFullerenes are found in space both through mid-infrared and optical\nspectroscopy and it is very likely that other complex related species such as\nendohedral fullerenes (i.e. fullerenes with a metal, heteroatom or molecules\ninside the cage) may be formed in space. After all, their formation requires\nthe same conditions as those needed for fullerene formation provided that also\na metal vapour (e.g. interstellar/circumstellar gas) is available. The last\npart of this review is thus dedicated to the recent results on the study and\ncharacterization of an endohedral C60 derivative containing lithium inside the\ncage.", "positive": "Nuclear star cluster formation in energy-space: In a virialized stellar system, the mean-square velocity is a direct tracer\nof the energy per unit mass of the system. Here, we exploit this to estimate\nand compare root-mean-square velocities for a large sample of nuclear star\nclusters and their host (late- or early-type) galaxies. Traditional\nobservables, such as the radial surface brightness and second-order velocity\nmoment profiles, are subject to short-term variations due to individual\nepisodes of matter infall and/or star formation. The total mass, energy and\nangular momentum, on the other hand, are approximately conserved. Thus, the\ntotal energy and angular momentum more directly probe the formation of galaxies\nand their nuclear star clusters, by offering access to more fundamental\nproperties of the nuclear cluster-galaxy system than traditional observables.\nWe find that there is a strong correlation, in fact a near equality, between\nthe root-mean-square velocity of a nuclear star cluster and that of its host.\nThus, the energy per unit mass of a nuclear star cluster is always comparable\nto that of its host galaxy. We interpret this as evidence that nuclear star\nclusters do not form independently of their host galaxies, but rather that\ntheir formation and subsequent evolution are coupled. We discuss how our\nresults can potentially be used to offer a clear and observationally testable\nprediction to distinguish between the different nuclear star cluster formation\nscenarios, and/or quantify their relative contributions." }, { "anchor": "HCN emission from translucent gas and UV-illuminated cloud edges\n revealed by wide-field IRAM 30m maps of Orion B GMC: Revisiting its role as\n tracer of the dense gas reservoir for star formation: We present 5 deg^2 (~250 pc^2) HCN, HNC, HCO+, and CO J=1-0 maps of the Orion\nB GMC, complemented with existing wide-field [CI] 492 GHz maps, as well as new\npointed observations of rotationally excited HCN, HNC, H13CN, and HN13C lines.\nWe detect anomalous HCN J=1-0 hyperfine structure line emission almost\neverywhere in the cloud. About 70% of the total HCN J=1-0 luminosity arises\nfrom gas at A_V < 8 mag. The HCN/CO J=1-0 line intensity ratio shows a bimodal\nbehavior with an inflection point at A_V < 3 mag typical of translucent gas and\nUV-illuminated cloud edges. We find that most of the HCN J=1-0 emission arises\nfrom extended gas with n(H2) ~< 10^4 cm^-3, even lower density gas if the\nionization fraction is > 10^-5 and electron excitation dominates. This result\nexplains the low-A_V branch of the HCN/CO J=1-0 intensity ratio distribution.\nIndeed, the highest HCN/CO ratios (~0.1) at A_V < 3 mag correspond to regions\nof high [CI] 492 GHz/CO J=1-0 intensity ratios (>1) characteristic of\nlow-density PDRs. Enhanced FUV radiation favors the formation and excitation of\nHCN on large scales, not only in dense star-forming clumps. The low surface\nbrightness HCN and HCO+ J=1-0 emission scale with I_FIR (a proxy of the stellar\nFUV radiation field) in a similar way. Together with CO J=1-0, these lines\nrespond to increasing I_FIR up to G0~20. On the other hand, the bright HCN\nJ=1-0 emission from dense gas in star-forming clumps weakly responds to I_FIR\nonce the FUV radiation field becomes too intense (G0>1500). The different power\nlaw scalings (produced by different chemistries, densities, and line excitation\nregimes) in a single but spatially resolved GMC resemble the variety of\nKennicutt-Schmidt law indexes found in galaxy averages. As a corollary for\nextragalactic studies, we conclude that high HCN/CO J=1-0 line intensity ratios\ndo not always imply the presence of dense gas.", "positive": "Low Surface Brightness Galaxies selected from the 40% sky area of the\n ALFALFA HI survey.I.Sample and statistical properties: The population of Low Surface Brightness (LSB) galaxies is crucial for\nunderstanding the extremes of galaxy formation and evolution of the universe.\nAs LSB galaxies are mostly rich in gas (HI), the alpha.40-SDSS DR7 sample is\nabsolutely one of the best survey combinations to select a sample of them in\nthe local Universe. Since the sky backgrounds are systematically overestimated\nfor galaxy images by the SDSS photometric pipeline, particularly for luminous\ngalaxies or galaxies with extended low surface brightness outskirts, in this\npaper, we above all estimated the sky backgrounds of SDSS images in the\nalpha.40-SDSS DR7 sample, using a precise method of sky subtraction. Once\nsubtracting the sky background, we did surface photometry with the Kron\nelliptical aperture and fitted geometric parameters with an exponential profile\nmodel for each galaxy image. Basing on the photometric and geometric results,\nwe further calculated the B-band central surface brightness, mu_{0}(B), for\neach galaxy and ultimately defined a sample of LSB galaxies consisting of 1129\ngalaxies with mu_{0}(B) > 22.5 mag arcsec^{-2} and the minor-to-major axis\nratio b/a > 0.3. This HI-selected LSB galaxy sample from the alpha.40-SDSS DR7\nis a relatively unbiased sample of gas-rich and disk-dominated LSB galaxies,\nwhich is complete both in HI observation and the optical magnitude within the\nlimit of SDSS DR7 photometric survey. We made analysis on optical and radio\n21cm HI properties of this LSB galaxy sample. Additionally, we statistically\ninvestigated the environment of our LSB galaxies, and found that up to 92% of\nthe total LSB galaxies have less than 8 neighbouring galaxies, which strongly\nevidenced that LSB galaxies prefer to reside in the low-density environment." }, { "anchor": "JSPAM: A restricted three-body code for simulating interacting galaxies: Restricted three-body codes have a proven ability to recreate much of the\ndisturbed morphology of actual interacting galaxies. As more sophisticated\nn-body models were developed and computer speed increased, restricted\nthree-body codes fell out of favor. However, their supporting role for\nperforming wide searches of parameter space when fitting orbits to real systems\ndemonstrates a continuing need for their use. Here we present the model and\nalgorithm used in the JSPAM code. A precursor of this code was originally\ndescribed in 1990, and was called SPAM. We have recently updated the software\nwith an alternate potential and a treatment of dynamical friction to more\nclosely mimic the results from n-body tree codes. The code is released publicly\nfor use under the terms of the Academic Free License (AFL) v.3.0 and has been\nadded to the Astrophysics Source Code Library.", "positive": "Radiative and Momentum Based Mechanical AGN Feedback in a 3-Dimensional\n Galaxy Evolution Code: We study the growth of black holes (BHs) in galaxies using three-dimensional\nsmoothed particle hydrodynamic simulations with new implementations of the\nmomentum mechanical feedback, and restriction of accreted elements to those\nthat are gravitationally bound to the BH. We also include the feedback from the\nX-ray radiation emitted by the BH, which heats the surrounding gas in the host\ngalaxies, and adds radial momentum to the fluid. We perform simulations of\nisolated galaxies and merging galaxies and test various feedback models with\nthe new treatment of the Bondi radius criterion. We find that overall the BH\ngrowth is similar to what has been obtained by earlier workers using the\nSpringel, Di Matteo, & Hernquist algorithms. However, the outflowing wind\nvelocities and mechanical energy emitted by winds are considerably higher (v_w\n~ 1000-3000 km/s) compared to the standard thermal feedback model (v_w ~ 50-100\nkm/s). While the thermal feedback model emits only 0.1 % of BH released energy\nin winds, the momentum feedback model emits more than 30 % of the total energy\nreleased by the BH in winds. In the momentum feedback model, the degree of\nfluctuation in both radiant and wind output is considerably larger than in the\nstandard treatments. We check that the new model of the BH mass accretion\nagrees with analytic results for the standard Bondi problem." }, { "anchor": "MUSE sneaks a peek at extreme ram-pressure stripping events - IV.\n Hydrodynamic and gravitational interactions in the Blue Infalling Group: We report new wide-field (~ 4 x 4 square arcmin) MUSE observations of the\nBlue Infalling Group (BIG), a compact group of galaxies located at a projected\ndistance of ~ 150 kpc from the X-Ray centre of the A1367 cluster at z = 0.021.\nOur MUSE observations map in detail the extended ionized gas, primarily traced\nby H$\\alpha$ emission, in between the members of the group. The gas morphology\nand its kinematics appear consistent with a tidal origin due to galaxy\nencounters, as also supported by the disturbed kinematics visible in one of the\ngroup members and the presence of tidal dwarf systems. A diffuse tail extending\nin the direction opposite to the cluster centre is also detected, hinting at a\nglobal ram-pressure stripping of the intra-group material as BIG falls inside\nA1367. Based on the analysis of spatially-resolved emission line maps, we\nidentify multiple ionization mechanisms for the diffuse gas filaments,\nincluding in situ photoionization from embedded HII regions and shocks.\nCombining spatially resolved kinematics and line ratios, we rule out the\nassociation of the most massive galaxy, CGCG097-120, with the group as this\nsystem appears to be decoupled from the intragroup medium and subject to strong\nram pressure as it falls into A1367. Through our new analysis, we conclude that\nBIG is shaped by pre-processing produced by gravitational interactions in the\nlocal group environment combined with ram pressure stripping by the global\ncluster halo.", "positive": "Galaxy And Mass Assembly: The 1.4GHz SFR indicator, SFR-M* relation and\n predictions for ASKAP-GAMA: We present a robust calibration of the 1.4GHz radio continuum star formation\nrate (SFR) using a combination of the Galaxy And Mass Assembly (GAMA) survey\nand the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey. We identify\nindividually detected 1.4GHz GAMA-FIRST sources and use a late-type, non-AGN,\nvolume-limited sample from GAMA to produce stellar mass-selected samples. The\nlatter are then combined to produce FIRST-stacked images. This extends the\nrobust parametrisation of the 1.4GHz-SFR relation to faint luminosities. For\nboth the individually detected galaxies and our stacked samples, we compare\n1.4GHz luminosity to SFRs derived from GAMA to determine a new 1.4GHz\nluminosity-to-SFR relation with well constrained slope and normalisation. For\nthe first time, we produce the radio SFR-M* relation over 2 decades in stellar\nmass, and find that our new calibration is robust, and produces a SFR-M*\nrelation which is consistent with all other GAMA SFR methods. Finally, using\nour new 1.4GHz luminosity-to-SFR calibration we make predictions for the number\nof star-forming GAMA sources which are likely to be detected in the upcoming\nASKAP surveys, EMU and DINGO." }, { "anchor": "Optical emission-line Luminosity Function models for populations of\n Supernova Remnants: We present a basic model for the calculation of the luminosity distribution\nof supernova remnant populations. We construct theoretical Ha and joint [S II]\n- Ha luminosity functions for supernova remnants by combining prescriptions\nfrom a basic evolution model that provides the shock velocity and radius for\nSNRs of different age and pre-shock density, with shock excitation models that\ngive the gas emissivity for shocks of different physical parameters. We assume\na flat age distribution, and we explore the effect of different pre-shock\ndensity distributions or different magnetic parameters. We find very good\nagreement between the shape of the model Ha and the joint [S II] - Ha\nluminosity functions and those measured from SNR surveys in nearby galaxies.", "positive": "A High-Resolution View of Fast Radio Burst Host Environments: We present Hubble Space Telescope (HST/WFC3) ultraviolet and infrared\nobservations of eight fast radio burst (FRB) host galaxies with sub-arcsecond\nlocalizations, including the hosts of three known repeating FRBs. We quantify\ntheir spatial distributions and locations with respect to their host galaxy\nlight distributions, finding that they occur at moderate host\nnormalized-offsets of 1.4 $r_e$ ([0.6,2.1] $r_e$; 68% interval), occur on\nfainter regions of their hosts in terms of IR light, but overall trace the\nradial distribution of IR light in their galaxies. The FRBs in our tested\ndistribution do not clearly trace the distributions of any other transient\npopulation with known progenitors, and are statistically distinct from the\nlocations of LGRBs, H-poor SLSNe, SGRBs, and Ca-rich transients. We further\nfind that most FRBs are not in regions of elevated local star formation rate\nand stellar mass surface densities in comparison to the mean global values of\ntheir hosts. We also place upper limits to the IR flux at the FRB positions of\n$m_{\\rm IR}\\gtrsim\\!24.8-27.6$~AB~mag, constraining both satellite and\nbackground galaxies to luminosities well below the host luminosity of\nFRB121102. We find that 5/8 FRB hosts exhibit clear spiral arm features in IR\nlight, and that the positions of all well-localized FRBs located in such hosts\nare consistent with their spiral arms, although not on their brightest regions.\nOur results do not strongly support the primary progenitor channel of FRBs\nbeing connected either with the most massive (stripped-envelope) stars, or with\nevents which require kicks and long delay times (neutron star mergers)." }, { "anchor": "Dependence of the IRX-$\u03b2$ dust attenuation relation on metallicity\n and environment: We use a sample of star-forming field and protocluster galaxies at z=2.0-2.5\nwith Keck/MOSFIRE K-band spectra, a wealth of rest-frame UV photometry, and\nSpitzer/MIPS and Herschel/PACS observations, to dissect the relation between\nthe ratio of IR to UV luminosity (IRX) versus UV slope ($\\beta$) as a function\nof gas-phase metallicity (12+log(O/H)~8.2-8.7). We find no significant\ndependence of the IRX-$\\beta$ trend on environment. However, we find that at a\ngiven $\\beta$, IRX is highly correlated with metallicity, and less correlated\nwith mass, age, and sSFR. We conclude that, of the physical properties tested\nhere, metallicity is the primary physical cause of the IRX-$\\beta$ scatter, and\nthe IRX correlation with mass is presumably due to the mass dependence on\nmetallicity. Our results indicate that the UV attenuation curve steepens with\ndecreasing metallicity, and spans the full range of slope possibilities from a\nshallow Calzetti-type curve for galaxies with the highest metallicity in our\nsample (12+log(O/H)~8.6) to a steep SMC-like curve for those with\n12+log(O/H)~8.3. Using a Calzetti (SMC) curve for the low (high) metallicity\ngalaxies can lead to up to a factor of 3 overestimation (underestimation) of\nthe UV attenuation and obscured SFR. We speculate that this change is due to\ndifferent properties of dust grains present in the ISM of low- and\nhigh-metallicity galaxies.", "positive": "ATLASGAL --- Complete compact source catalogue: 280\\degr\\ $ <\\ell <$\n 60\\degr: The APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) is the largest\nand most sensitive systematic survey of the inner Galactic plane in the\nsubmillimetre wavelength regime. The observations were carried out with the\nLarge APEX Bolometer Camera (LABOCA), an array of 295 bolometers observing at\n870\\,$\\mu$m (345 GHz). Aim: In this research note we present the compact source\ncatalogue for the 280\\degr\\ $ <\\ell <$ 330\\degr\\ and 21\\degr\\ $ <\\ell <$\n60\\degr\\ regions of this survey. Method: The construction of this catalogue was\nmade with the source extraction routine \\sex\\ using the same input parameters\nand procedures used to analyse the inner Galaxy region presented in an earlier\npublication (i.e., 330\\degr\\ $ <\\ell <$ 21\\degr). Results: We have identified\n3523 compact sources and present a catalogue of their properties. When combined\nwith the regions already published this provides a comprehensive and unbiased\ndatabase of ~10163 massive, dense clumps located across the inner Galaxy." }, { "anchor": "The Fornax Deep Survey (FDS) with the VST XI. The search for signs of\n preprocessing between the Fornax main cluster and Fornax A group: We investigate the structural properties of cluster and group galaxies by\nstudying the Fornax main cluster and the infalling Fornax A group, exploring\nthe effects of galaxy preprocessing in this showcase example. Additionally, we\ncompare the structural complexity of Fornax galaxies to those in the Virgo\ncluster and in the field. Our sample consists of 582 galaxies from the Fornax\nmain cluster and Fornax A group. We quantified the light distributions of each\ngalaxy based on a combination of aperture photometry, S\\'ersic+PSF (point\nspread function) and multi-component decompositions, and non-parametric\nmeasures of morphology (Concentration $C$; Asymmetry $A$, Clumpiness $S$; Gini\n$G$; second order moment of light $M_{20}$), and structural complexity based on\nmulti-component decompositions. These quantities were then compared between the\nFornax main cluster and Fornax A group. The structural complexity of Fornax\ngalaxies were also compared to those in Virgo and in the field. Overall, we\nfind significant differences in the distributions of quantities derived from\nS\\'ersic profiles ($g'-r'$, $r'-i'$, $R_e$, and $\\bar{\\mu}_{e,r'}$), and\nnon-parametric indices ($A$ and $S$) between the Fornax main cluster and Fornax\nA group. Moreover, we find significant cluster-centric trends with $r'-i'$,\n$R_e$, and $\\bar{\\mu}_{e,r'}$, as well as $A$, $S$, $G$, and $M_{20}$ for\ngalaxies in the Fornax main cluster. We find the structural complexity of\ngalaxies increases as a function of the absolute $r'$-band magnitude (and\nstellar mass), with the largest change occurring between -14 mag $\\lesssim\nM_{r'}\\lesssim$ -19 mag. This same trend was observed for galaxies in the Virgo\ncluster and in the field, which suggests that the formation or maintenance of\nmorphological structures (e.g. bulges, bar) is largely dependent on the stellar\nmass of the galaxies, rather than their environment.", "positive": "Protostellar-disc fragmentation across all metallicities: Cosmic metallicity evolution possibly creates the diversity of star formation\nmodes at different epochs. Gravitational fragmentation of circumstellar discs\nprovides an important formation channel of multiple star systems, including\nclose binaries. We here study the nature of disc fragmentation, systematically\nperforming a suite of two-dimensional radiation-hydrodynamic simulations, in a\nbroad range of metallicities, from the primordial to the solar values. In\nparticular, we follow relatively long-term disc evolution over 15 kyr after the\ndisc formation, incorporating the effect of heating by the protostellar\nirradiation. Our results show that the disc fragmentation occurs at all\nmetallicities $1$--$0$ $Z_{\\odot}$, yielding self-gravitating clumps. Physical\nproperties of the clumps, such as their number and mass distributions, change\nwith the metallicity due to different gas thermal evolution. For instance, the\nnumber of clumps is the largest for the intermediate metallicity range of\n$10^{-2}$--$10^{-5}$ $Z_{\\odot}$, where the dust cooling is effective\nexclusively in a dense part of the disc and causes the fragmentation of spiral\narms. The disc fragmentation is more modest for $1$--$0.1$ $Z_{\\odot}$ thanks\nto the disc stabilization by the stellar irradiation. Such metallicity\ndependence agrees with the observed trend that the close binary fraction\nincreases with decreasing metallicity in the range of $1$--$10^{-3}$\n$Z_{\\odot}$." }, { "anchor": "Binary stars as probes of dark substructures in dwarf galaxies: We use analytical and N-body methods to examine the survival of wide stellar\nbinaries against repeated encounters with dark substructures orbiting in the\ndark matter haloes of dwarf spheroidal galaxies (dSphs). Our models adopt\ncosmologically-motivated conditions wherein dSphs are dark-matter dominated\nsystems that form hierarchically and orbit about a host galaxy. Our analytical\nestimates show that wide binaries are disrupted at a rate that is proportional\nto the local density of dark substructures averaged over the life-time of the\nbinary population. The fact that external tides can efficiently strip dark\nsubstructures from the outskirts of dSphs implies that the present number and\ndistribution of binaries is strongly coupled with the mass evolution of\nindividual galaxies. Yet we show that for the range of dynamical masses and\nGalactocentric distances spanned by Milky Way dSphs, a truncation in the\nseparation function at a_max <~ 0.1 pc is expected in all these galaxies. An\nexception may be the Sagittarius dSph, which has lost most of is dark matter\nenvelope to tides and is close to full disruption. Our simulations indicate\nthat at separations larger than a_max the perturbed binary distribution scales\nas dN/da \\propto a^{-2.1} independently of the mass and density of\nsubstructures. These results may be used to determine whether the binary\nseparation function found in dwarf galaxies is compatible with the scale-free\nhierarchical picture that envisions the existence of dark substructures in all\ngalactic haloes. We show that the ACS camera on board of the Hubble telescope\nmay be able to test this prediction in dSphs at heliocentric distances <100\nkpc, even if the binary fraction amounts only 10% of the stellar population.", "positive": "Eventful Evolution of Giant Molecular Clouds in Dynamically Evolving\n Spiral Arms: The formation and evolution of giant molecular clouds (GMCs) in spiral\ngalaxies have been investigated in the traditional framework of the combined\nquasi-stationary density wave and galactic shock model. However, our\nunderstanding of the dynamics of spiral arms is changing from the traditional\nspiral model to a dynamically evolving spiral model. In this study, we\ninvestigate the structure and evolution of GMCs in a dynamically evolving\nspiral arm using a three-dimensional N-body/hydrodynamic simulation of a barred\nspiral galaxy at parsec-scale resolution. This simulation incorporated\nself-gravity, molecular hydrogen formation, radiative cooling, heating due to\ninterstellar far-ultraviolet radiation, and stellar feedback by both HII\nregions and Type-II supernovae. In contrast to a simple expectation based on\nthe traditional spiral model, the GMCs exhibited no systematic evolutionary\nsequence across the spiral arm. Our simulation showed that the GMCs behaved as\nhighly dynamic objects with eventful lives involving collisional build-up,\ncollision-induced star formation, and destruction via stellar feedback. The GMC\nlifetimes were predicted to be short, only a few tens of millions years. We\nalso found that, at least at the resolutions and with the feedback models used\nin this study, most of the GMCs without HII regions were collapsing, but half\nof the GMCs with HII regions were expanding owing to the HII-region feedback\nfrom stars within them. Our results support the dynamic and feedback-regulated\nGMC evolution scenario. Although the simulated GMCs were converging rather than\nvirial equilibrium, they followed the observed scaling relationship well. We\nalso analysed the effects of galactic tides and external pressure on GMC\nevolution and suggested that GMCs cannot be regarded as isolated systems since\ntheir evolution in disc galaxies is complicated because of these environmental\neffects." }, { "anchor": "Acceleration of small astrophysical grains due to charge fluctuations: We discuss a novel mechanism of dust acceleration which may dominate for\nparticles smaller than $\\sim0.1~\\mu$m. The acceleration is caused by their\ndirect electrostatic interactions arising from fluctuations of grain charges.\nThe energy source for the acceleration are the irreversible plasma processes\noccurring on the grain surfaces. We show that this mechanism of\ncharge-fluctuation-induced acceleration likely affects the rate of grain\ncoagulation and shattering of the population of small grains.", "positive": "Exposing Sgr tidal debris behind the Galactic disk with M giants\n selected in WISE$\\cap$2MASS: We show that a combination of infrared photometry from WISE and 2MASS surveys\ncan yield highly pure samples of M giant stars. We take advantage of the new\nWISE$\\cap$2MASS M giant selection to trace the Sagittarius trailing tail behind\nthe Galactic disk in the direction of the anti-centre. The M giant candidates\nselected via broad-band photometry are confirmed spectroscopically using\nAAOmega on the AAT in 3 fields around the extremity of the Sgr trailing tail in\nthe Southern Galactic hemisphere. We demonstrate that at the Sgr longitude\n$\\tilde \\Lambda_{\\odot} = 204^{\\circ}$, the line-of-sight velocity of the\ntrailing tail starts to deviate from the track of the Law & Majewski (2010)\nmodel, confirming the prediction of Belokurov et al. (2014). This discovery\nserves to substantiate the measurement of low differential orbital precession\nof the Sgr stream which in turn may imply diminished dark matter content within\n100 kpc." }, { "anchor": "Turbulence sets the initial conditions for star formation in\n high-pressure environments: Despite the simplicity of theoretical models of supersonically turbulent,\nisothermal media, their predictions successfully match the observed gas\nstructure and star formation activity within low-pressure (P/k < 10^5 K cm^-3)\nmolecular clouds in the solar neighbourhood. However, it is unknown if these\ntheories extend to clouds in high-pressure (P/k > 10^7 K cm^-3) environments,\nlike those in the Galaxy's inner 200 pc Central Molecular Zone (CMZ) and in the\nearly Universe. Here we present ALMA 3mm dust continuum emission within a\ncloud, G0.253+0.016, which is immersed in the high-pressure environment of the\nCMZ. While the log-normal shape and dispersion of its column density PDF is\nstrikingly similar to those of solar neighbourhood clouds, there is one\nimportant quantitative difference: its mean column density is 1--2 orders of\nmagnitude higher. Both the similarity and difference in the PDF compared to\nthose derived from solar neighbourhood clouds match predictions of turbulent\ncloud models given the high-pressure environment of the CMZ. The PDF shows a\nsmall deviation from log-normal at high column densities confirming the youth\nof G0.253+0.016. Its lack of star formation is consistent with the\ntheoretically predicted, environmentally dependent volume density threshold for\nstar formation which is orders of magnitude higher than that derived for solar\nneighbourhood clouds. Our results provide the first empirical evidence that the\ncurrent theoretical understanding of molecular cloud structure derived from the\nsolar neighbourhood also holds in high-pressure environments. We therefore\nsuggest that these theories may be applicable to understand star formation in\nthe early Universe.", "positive": "The effect of gaseous accretion disk on dynamics of the stellar cluster\n in AGN: There is a supermassive black hole, a gaseous accretion disk and compact star\ncluster in the center of active galactic nuclei, as known today. So the\nactivity of AGN can be represented as the result of interaction of these three\nsubsystems. In this work we investigate the dynamical interaction of a central\nstar cluster surrounding a supermassive black hole and a central accretion\ndisk. The dissipative force acting on stars in the disk leads to an asymmetry\nin the phase space distribution of the central star cluster due to the rotating\naccretion disk. In our work we present some results of Stardisk model, where we\nsee some changes in density and phase space of central star cluster due to\ninfluence of rotating gaseous accretion disk." }, { "anchor": "Early growth of typical high redshift black holes seeded by direct\n collapse: Understanding the growth of high redshift massive black holes (MBHs) is a\nproblem of great astrophysical interest. The most luminous quasars at $z>6$ are\nfrequently observed but they represent only the tip of the iceberg as the\nmajority of the low luminosity AGN population remains undetected. In the\npresent study, we perform a radiation hydrodynamics cosmological simulation to\nstudy the growth of \"normal\" black holes in the high redshift universe. In our\nsimulation we model the formation of Pop III and Pop II stars along with their\nchemical, mechanical and radiative feedback. We consider both UV and X-ray\nemission from an accreting BH to simulate its radiative feedback. The selected\nhalo has a mass of $\\rm 3 \\times 10^{10}~M_{\\odot}$ at $z=7.5$ and we turn on\nradiative feedback from a MBH seed of $\\rm 10^5~M_{\\odot}$ along with in-situ\nstar formation at $z=12$ when the halo mass reaches well above the atomic\ncooling limit. We find that the MBH accretes only about 2200 $\\rm M_{\\odot}$\nduring 320 Myr and the average mass accretion onto the MBH is a few times $\\rm\n10^{-6}~M_{\\odot}/yr$. Our results suggest that the stunted growth of MBH is a\nconsequence of supernovae in tandem with MBH feedback which drive large\noutflows and evacuate the gas from MBH vicinity. This may explain why a\npopulation of low luminosity AGN has not been detected so-far at $z>6$; the\nlarge contrast between the star formation rate and the MBH accretion rate may\nmake then hard to detect even in upcoming deep surveys.", "positive": "Kiloparsec-scale Radio Structures in Narrow-line Seyfert 1 Galaxies: We report the finding of kiloparsec (kpc)-scale radio structures in three\nradio-loud narrow-line Seyfert 1 (NLS1) galaxies from the Faint Images of the\nRadio Sky at Twenty-centimeters (FIRST) of the Very Large Array (VLA), which\nincreases the number of known radio-loud NLS1s with kpc-scale structures to\nsix, including two gamma-ray emitting NLS1s (PMN J0948+0022 and 1H 0323+342)\ndetected by the Fermi Gamma-ray Space Telescope. The detection rate of extended\nradio emissions in NLS1s is lower than that in broad-line active galactic\nnuclei (AGNs) with a statistical significance. We found both core-dominated\n(blazar-like) and lobe-dominated (radio-galaxy-like) radio structures in these\nsix NLS1s, which can be understood in the framework of the unified scheme of\nradio-loud AGNs that considers radio galaxies as non-beamed parent populations\nof blazars. Five of the six NLS1s have (i) extended radio luminosities\nsuggesting jet kinetic powers of >~10^44 erg/s, which is sufficient to make\njets escape from hosts' dense environments, (ii) black holes of >~10^7 solar\nmass, which can generate the necessary jet powers from near-Eddington mass\naccretion, and (iii) two-sided radio structures at kpc scales, requiring\nexpansion rates of ~0.01c--0.3c and kinematic ages of >~10^7 years. On the\nother hand, most typical NLS1s would be driven by black holes of <~10^7 solar\nmass in a limited lifetime of ~10^7 years. Hence the kpc-scale radio structures\nmay originate in a small window of opportunity during the final stage of the\nNLS1 phase just before growing into broad-line AGNs." }, { "anchor": "The nebulae around LBVs: a multiwavelength approach: We present first results of our study of a sample of Galactic LBV, aimed to\ncontribute to a better understanding of the LBV phenomenon, by recovering the\nmass-loss history of the central object from the analysis of its associated\nnebula. Mass-loss properties have been derived by a synergistic use of\ndifferent techniques, at different wavelengths, to obtain high-resolution,\nmulti-wavelength maps, tracing the different emitting components coexisting in\nthe stellar ejecta: the ionized/neutral gas and the dust. Evidence for\nasymmetric mass-loss and observational evidence of possible mutual interaction\nbetween gas and dust components have been observed by the comparison of mid-IR\n(Spitzer/IRAC, VLT/VISIR) and radio (VLA) images of the nebulae, while\nimportant information on the gas and dust composition have been derived from\nSpitzer/IRS spectra.", "positive": "Star formation history of the post-collisional Cartwheel galaxy using\n Astrosat/UVIT FUV images: We present the results obtained by analysing new Astrosat/UVIT far\nultraviolet (FUV) image of the collisional-ring galaxy Cartwheel. The FUV\nemission is principally associated with the star-forming outer ring, with no UV\ndetection from the nucleus and inner ring. A few sources are detected in the\nregion between the inner and the outer rings, all of which lie along the\nspokes. The FUV fluxes from the detected sources are combined with\naperture-matched multi-band photometric data from archival images to explore\nthe post-collision star formation history of the Cartwheel. The data were\ncorrected for extinction using Av derived from the Balmer decrement ratios and\ncommonly used extinction curves. We find that the ring regions contain stellar\npopulations of wide range of ages, with the bulk of the FUV emission coming\nfrom non-ionizing stars, formed over the last 20 to 150 Myr, that are ~25 times\nmore massive than the ionizing populations. On the other hand, regions\nbelonging to the spokes have negligible current star formation, with the age of\nthe dominant older population systematically increasing as its distance from\nthe outer ring increases. The presence of populations of a wide range of ages\nin the ring suggests that the stars formed in the wave in the past were dragged\nalong it to the current position of the ring. We derive an average steady star\nformation rate, SFR=5 Msun/yr, over the past 150 Myr, with an increase to ~18\nMsun/yr in the recent 10 Myr." }, { "anchor": "Effects of the selection function on metallicity trends in spectroscopic\n surveys of the Milky Way: We investigate here the effect of the selection function on the metallicity\ndistribution function (MDF) and on the vertical metallicity gradient by\nstudying similar lines of sight using four different spectroscopic surveys\n(APOGEE, LAMOST, RAVE, and Gaia-ESO), which have different targeting strategies\nand therefore different selection functions. We use common fields between the\nspectroscopic surveys of APOGEE, LAMOST, RAVE (ALR) and APOGEE, RAVE, Gaia-ESO\n(AGR) and use two stellar population synthesis models, GALAXIA and TRILEGAL, to\ncreate mock fields for each survey. We apply the selection function in the form\nof colour and magnitude cuts of the respective survey to the mock fields to\nreplicate the observed source sample. We make a basic comparison between the\nmodels to check which best reproduces the observed sample distribution. We\ncarry out a quantitative comparison between the synthetic MDF from the mock\ncatalogues using both models to understand the effect of the selection function\non the MDF and on the vertical metallicity gradient. Using both models, we find\na negligible effect of the selection function on the MDF for APOGEE, LAMOST,\nand RAVE. We find a negligible selection function effect on the vertical\nmetallicity gradients as well, though GALAXIA and TRILEGAL have steeper and\nshallower slopes, respectively, than the observed gradient. After applying\ncorrection terms on the metallicities of RAVE and LAMOST with respect to our\nreference APOGEE sample, our observed vertical metallicity gradients between\nthe four surveys are consistent within 1-sigma. We also find consistent\ngradient for the combined sample of all surveys in ALR and AGR. We estimated a\nmean vertical metallicity gradient of -0.241+/-0.028 dex kpc-1. There is a\nsignificant scatter in the estimated gradients in the literature, but our\nestimates are within their ranges.", "positive": "The Arecibo L-band Feed Array Zone of Avoidance (ALFAZOA) Shallow Survey: The Arecibo L-band Feed Array Zone of Avoidance (ALFAZOA) Shallow Survey is a\nblind HI survey of the extragalactic sky behind the northern Milky Way\nconducted with the ALFA receiver on the 305m Arecibo Radio Telescope. ALFAZOA\nShallow covered 900 square degrees at full sensitivity from 30{\\deg} ${\\leq} l\n{\\leq} $75{\\deg} and |b|$ {\\leq}$ 10{\\deg} and an additional 460 square degrees\nat limited sensitivity at latitudes up to 20{\\deg}. It has an rms sensitivity\nof 5-7 mJy and a velocity resolution of 9 - 20.6 km s$^{-1}$, and detected 403\ngalaxies out to a recessional velocity of 12,000 km s$^{-1}$, with an angular\nresolution of 3.4' and a positional accuracy between 0.2' and 1.7'. The survey\nis complete above an integrated line flux $F_{HI}$ = 2.0 Jy km s$^{-1}$ for\nhalf the survey, and above $F_{HI}$ = 2.8 Jy km s$^{-1}$ for the other half.\n Forty-three percent of the ALFAZOA HI detections have at least one possible\noptical/NIR counterpart in the literature, and an additional 16% have\ncounterparts that only included previous HI measurements. There are fewer\ncounterparts in regions of high extinction and for galaxies with lower HI mass.\nComparing the results of the survey to the predictions of Erdogdu et al.\n(2006), and using their nomenclature, ALFAZOA confirms the position and extent\nin the ZOA of the C7, C${\\zeta}$, Pegasus, Corona Borealis and Delphinus\nstructures, but not of the Cygnus void. Two new structures are identified, both\nconnected to the C7 overdensity; one extends to 35{\\deg}, and the other crosses\nthe ZOA." }, { "anchor": "Gaia Data Release 2: The catalogue of radial velocity standard stars: Aims. The Radial Velocity Spectrometer (RVS) on board the ESA satellite\nmission Gaia has no calibration device. Therefore, the radial velocity zero\npoint needs to be calibrated with stars that are proved to be stable at a level\nof 300 m/s during the Gaia observations. Methods. We compiled a dataset of\n~71000 radial velocity measurements from five high-resolution spectrographs. A\ncatalogue of 4813 stars was built by combining these individual measurements.\nThe zero point was established using asteroids. Results. The resulting\ncatalogue has seven observations per star on average on a typical time baseline\nof six years, with a median standard deviation of 15 m/s. A subset of the most\nstable stars fulfilling the RVS requirements was used to establish the radial\nvelocity zero point provided in Gaia Data Release 2. The stars that were not\nused for calibration are used to validate the RVS data.", "positive": "Using Red Clump Stars to Decompose the Galactic Magnetic Field with\n Distance: A new method for measuring the large-scale structure of the Galactic magnetic\nfield is presented. The Galactic magnetic field has been probed through the\nGalactic disk with near-infrared starlight polarimetry, however the distance to\neach background star is unknown. Using red clump stars as near-infrared\nstandard candles, this work presents the first attempt to decompose the line of\nsight structure of the sky-projected Galactic magnetic field. Two example\nlines-of-sight are decomposed: toward a field with many red clump stars and\ntoward a field with few red clump stars. A continuous estimate of magnetic\nfield orientation over several kiloparsecs of distance is possible in the field\nwith many red clump stars, while only discrete estimates are possible in the\nsparse example. toward the Outer Galaxy, there is a continuous field\norientation with distance that shows evidence of perturbation by the Galactic\nwarp. toward the Inner Galaxy, evidence for a large-scale change in the\nmagnetic field geometry is consistent with models of magnetic field reversals,\nindependently derived from Faraday rotation studies. A photo-polarimetric\nmethod for identifying candidate intrinsically polarized stars is also\npresented. The future application of this method to large regions of the sky\nwill begin the process of mapping the Galactic magnetic field in a way never\nbefore possible." }, { "anchor": "Amplification of OAM Radiation by Astrophysical Masers: We extend the theory of astrophysical maser propagation through a medium with\na Zeeman-split molecular response to the case of a non-uniform magnetic field,\nand allow a component of the electric field of the radiation in the direction\nof propagation: a characteristic of radiation with orbital angular momentum. A\nclassical reduction of the governing equations leads to a set of nine\ndifferential equations for the evolution of intensity-like parameters for each\nFourier component of the radiation. Four of these parameters correspond to the\nstandard Stokes parameters, whilst the other five represent the $z$-component\nof the electric field, and its coupling to the conventional components in the\n$x-y$-plane. A restricted analytical solution of the governing equations\ndemonstrates a non-trivial coupling of the Stokes parameters to those\nrepresenting orbital angular momentum: the $z$-component of the electric field\ncan grow from a background in which only Stokes-$I$ is non-zero. A numerical\nsolution of the governing equations reveals radiation patterns with a radial\nand angular structure for the case of an ideal quadrupole magnetic field\nperpendicular to the propagation direction. In this ideal case generation of\nradiation orbital angular momentum, like polarization, can approach 100 per\ncent.", "positive": "The Green Bank Ammonia Survey: Dense Cores Under Pressure in Orion A: We use gas temperature and velocity dispersion data from the Green Bank\nAmmonia Survey and core masses and sizes from the James Clerk Maxwell Telescope\nGould Belt Survey to estimate the virial states of dense cores within the Orion\nA molecular cloud. Surprisingly, we find that almost none of the dense cores\nare sufficiently massive to be bound when considering only the balance between\nself-gravity and the thermal and non-thermal motions present in the dense gas.\nIncluding the additional pressure binding imposed by the weight of the ambient\nmolecular cloud material and additional smaller pressure terms, however,\nsuggests that most of the dense cores are pressure confined." }, { "anchor": "Initial Conditions for Star Formation: A Physical Description of the\n Filamentary ISM: The interstellar medium contains filamentary structure over a wide range of\nscales. Understanding the role of this structure, both as a conduit of gas\nacross the scales and a diagnostic tool of local physics, is a major focus of\nstar formation studies. We review recent progress in studying filamentary\nstructure in the ISM, interpreting its properties in terms of physical\nprocesses, and exploring formation and evolution scenarios. We include\nstructures from galactic-scale filaments to tenth-of-a-parsec scale filaments,\ncomprising both molecular and atomic structures, from both observational and\ntheoretical perspectives. In addition to the literature overview, we assemble a\nlarge amount of catalogue data from different surveys and provide the most\ncomprehensive census of filamentary structures to date. Our census consists of\n22 803 filamentary structures, facilitating a holistic perspective and new\ninsights. We use our census to conduct a meta-analysis, leading to a\ndescription of filament properties over four orders of magnitudes in length and\neight in mass. Our analysis emphasises the hierarchical and dynamical nature of\nfilamentary structures. Filaments do not live in isolation, nor they generally\nresemble static structures close to equilibrium. We propose that accretion\nduring filament formation and evolution sets some of the key scaling properties\nof filaments. This highlights the role of accretion during filament formation\nand evolution and also in setting the initial conditions for star formation.\nOverall, the study of filamentary structures during the past decade has been\nobservationally driven. While great progress has been made on measuring the\nbasic properties of filaments, our understanding of their formation and\nevolution is clearly lacking. In this context, we identify a number of\ndirections and questions we consider most pressing for the field.", "positive": "Fragmentation and disk formation during high-mass star formation: The\n IRAM NOEMA (Northern Extended Millimeter Array) large program CORE: Aims: We aim to understand the fragmentation as well as the disk formation,\noutflow generation and chemical processes during high-mass star formation on\nspatial scales of individual cores.\n Methods: Using the IRAM Northern Extended Millimeter Array (NOEMA) in\ncombination with the 30m telescope, we have observed in the IRAM large program\nCORE the 1.37mm continuum and spectral line emission at high angular resolution\n(~0.4'') for a sample of 20 well-known high-mass star-forming regions with\ndistances below 5.5kpc and luminosities larger than 10^4Lsun.\n Results: We present the overall survey scope, the selected sample, the\nobservational setup and the main goals of CORE. Scientifically, we concentrate\non the mm continuum emission on scales on the order of 1000AU. We detect strong\nmm continuum emission from all regions, mostly due to the emission from cold\ndust. The fragmentation properties of the sample are diverse. We see extremes\nwhere some regions are dominated by a single high-mass core whereas others\nfragment into as many as 20 cores. A minimum-spanning-tree analysis finds\nfragmentation at scales on the order of the thermal Jeans length or smaller\nsuggesting that turbulent fragmentation is less important than thermal\ngravitational fragmentation. The diversity of highly fragmented versus singular\nregions can be explained by varying initial density structures and/or different\ninitial magnetic field strengths.\n Conclusions: The smallest observed separations between cores are found around\nthe angular resolution limit which indicates that further fragmentation likely\ntakes place on even smaller spatial scales. The CORE project with its numerous\nspectral line detections will address a diverse set of important physical and\nchemical questions in the field of high-mass star formation." }, { "anchor": "The SAMI Galaxy Survey: Kinematics of stars and gas in brightest group\n galaxies; the role of group dynamics: We study the stellar and gas kinematics of the brightest group galaxies\n(BGGs) in dynamically relaxed and unrelaxed galaxy groups for a sample of 154\ngalaxies in the SAMI galaxy survey. We characterize the dynamical state of the\ngroups using the luminosity gap between the two most luminous galaxies and the\nBGG offset from the luminosity centroid of the group. We find that the\nmisalignment between the rotation axis of gas and stellar components is more\nfrequent in the BGGs in unrelaxed groups, although with quite low statistical\nsignificance. Meanwhile galaxies whose stellar dynamics would be classified as\n`regular rotators' based on their kinemetry are more common in relaxed groups.\nWe confirm that this dependency on group dynamical state remains valid at fixed\nstellar mass and Sersic index. The observed trend could potentially originate\nfrom a differing BGG accretion history in virialised and evolving groups.\nAmongst the halo relaxation probes, the group BGG offset appears to play a\nstronger role than the luminosity gap on the stellar kinematic differences of\nthe BGGs. However, both the group BGG offset and luminosity gap appear to\nroughly equally drive the misalignment between the gas and stellar component of\nthe BGGs in one direction. This study offers the first evidence that the\ndynamical state of galaxy groups may influence the BGG's stellar and gas\nkinematics and calls for further studies using a larger sample with higher\nsignal-to-noise.", "positive": "The Role of Stellar Feedback in the Chemical Evolution of a Low Mass\n Dwarf Galaxy: We investigate how each aspect of a multi-channel stellar feedback model\ndrives the chemodynamical evolution of a low-mass, isolated dwarf galaxy using\na suite of high-resolution simulations. Our model follows individual star\nparticles sampled randomly from an adopted initial mass function, considering\nindependently feedback from: supernovae; stellar radiation causing\nphotoelectric heating of dust grains, ionization and associated heating,\nLyman-Werner (LW) dissociation of H$_2$, and radiation pressure; and winds from\nmassive main sequence (neglecting their energy input) and asymptotic giant\nbranch (AGB) stars. Radiative transfer is done by ray tracing. We consider the\neffects each of these processes have on regulating the star formation rate,\nglobal properties, multi-phase interstellar medium (ISM), and driving of\ngalactic winds. We follow individual metal species from distinct\nnucleosynthetic enrichment channels (AGB winds, massive star stellar winds,\ncore collapse and Type Ia supernovae) and pay particular attention to how these\nfeedback processes regulate metal mixing in the ISM, the metal content of\noutflows, and the stellar abundance patterns in our galaxy. We find that---for\na low-metallicity, low-mass dwarf galaxy ---stellar radiation, particularly\nionizing radiation and LW radiation, are important sources of stellar feedback\nwhose effects dominate over photoelectric heating and HI radiation pressure.\nHowever, feedback is coupled non-linearly, and the inclusion or exclusion of\neach process produces non-negligible effects. We find strong variations with:\nthe star formation history; the ejection fractions of metals, mass, and energy;\nand the distribution of elements from different nucleosynthetic sources in both\nthe gas and stars." }, { "anchor": "Secular resonant dressed orbital diffusion II : application to an\n isolated self similar tepid galactic disc: The main orbital signatures of the secular evolution of an isolated\nself-gravitating stellar Mestel disc are recovered using a dressed\nFokker-Planck formalism in angle-action variables. The shot-noise-driven\nformation of narrow ridges of resonant orbits is recovered in the WKB limit of\ntightly wound transient spirals, for a tepid Toomre-stable tapered disc. The\nrelative effect of the bulge, the halo, the disc temperature and the spectral\nproperties of the shot noise are investigated in turn. For such galactic discs\nall elements seem to impact the locus and direction of the ridge. For instance,\nwhen the halo mass is decreased, we observe a transition between a regime of\nheating in the inner regions of the disc through the inner Lindblad resonance\nto a regime of radial migration of quasi-circular orbits via the corotation\nresonance in the outer part of the disc. The dressed secular formalism captures\nboth the nature of collisionless systems (via their natural frequencies and\nsusceptibility), and their nurture via the structure of the external perturbing\npower spectrum. Hence it provides the ideal framework in which to study their\nlong term evolution.", "positive": "Eppur si muove: Positional and kinematic correlations of satellite pairs\n in the low Z universe: We have recently shown (Ibata et al. 2014) that pairs of satellite galaxies\nlocated diametrically opposite each other around their host possess\npredominantly anti-correlated velocities. This is consistent with a scenario in\nwhich $\\sim 50$% of satellite galaxies belong to kinematically-coherent\nrotating planar structures, similar to those detected around the giant galaxies\nof the Local Group. Here we extend this analysis, examining the incidence of\nsatellites of giant galaxies drawn from an SDSS photometric redshift catalog.\nWe find that there is a $\\sim 17$% overabundance ($> 3 \\sigma$ significance) of\ncandidate satellites at positions diametrically opposite a spectroscopically\nconfirmed satellite. We show that cosmological simulations do not possess this\nproperty when the contamination is included, and that there are in fact, after\nsubtracting contamination, 2 to 3 times more satellites diametrically opposed\nto a spectroscopically confirmed satellite than at $90\\deg$ from it. We also\nexamine the correlation between the satellite pair positions and the\norientation of the host galaxy major axis. We find that those satellite pairs\nwith anti-correlated velocities have a strong preference ($\\sim 3:1$) to align\nwith the major axis of the host whereas those with correlated velocities\ndisplay the opposite behavior. This correlation of the satellite alignments\nappears to be stronger than the well-documented preference of satellites to be\nlocated close to the major axis of their host. We finally show that repeating a\nsimilar analysis to Ibata et al. (2014) with same-side satellites is generally\nhard to interpret, but is not inconsistent with our previous results when\nstrong quality-cuts are applied on the sample. All these unexpected\ncorrelations strongly suggest that a substantial fraction of satellite galaxies\nare causally-linked in their formation and evolution." }, { "anchor": "Observations of Diffuse Ultraviolet Emission from Draco: We have studied small scale (2 arcmin) spatial variation of the diffuse UV\nradiation using a set of 11 GALEX deep observations in the constellation of\nDraco. We find a good correlation between the observed UV background and the IR\n100 micron flux, indicating that the dominant contributor of the diffuse\nbackground in the field is the scattered starlight from the interstellar dust\ngrains. We also find strong evidence of additional emission in the FUV band\nwhich is absent in the NUV band. This is most likely due to Lyman band emission\nfrom molecular hydrogen in a ridge of dust running through the field and to\nline emissions from species such as C IV (1550 A) and Si II (1533 A) in the\nrest of the field. A strong correlation exists between the FUV/NUV ratio and\nthe FUV intensity in the excess emission regions in the FUV band irrespective\nof the optical depth of the region. The optical depth increases more rapidly in\nthe UV than the IR and we find that the UV/IR ratio drops off exponentially\nwith increasing IR due to saturation effects in the UV. Using the positional\ndetails of Spitzer extragalactic objects, we find that the contribution of\nextragalactic light in the diffuse NUV background is 49 +/- 13 photon units and\nis 30 +/- 10 photon units in the FUV band.", "positive": "Testing galaxy formation models with galaxy stellar mass functions: We compare predictions of a number of empirical models and numerical\nsimulations of galaxy formation to the conditional stellar mass functions\n(CSMF)of galaxies in groups of different masses obtained recently by Lan et al.\nto test how well different models accommodate the data. The observational data\nclearly prefer a model in which star formation in low-mass halos changes\nbehavior at a characteristic redshift $z_c\\sim 2$. There is also tentative\nevidence that this characteristic redshift depends on environment, becoming\n$z_c\\sim 4$ in regions that eventually evolve into rich clusters of galaxies.\nThe constrained model is used to understand how galaxies form and evolve in\ndark matter halos, and to make predictions for other statistical properties of\nthe galaxy population, such as the stellar mass functions of galaxies at high\n$z$, the star formation and stellar mass assembly histories in dark matter\nhalos. A comparison of our model predictions with those of other empirical\nmodels shows that different models can make vastly different predictions, even\nthough all of them are tuned to match the observed stellar mass functions of\ngalaxies." }, { "anchor": "Complex molecules toward low-mass protostars: the Serpens core: Gas-phase complex organic molecules are commonly detected toward high-mass\nprotostellar hot cores. Detections toward low-mass protostars and outflows are\ncomparatively rare, and a larger sample is key to investigate how the chemistry\nresponds to its environment. Guided by the prediction that complex organic\nmolecules form in CH3OH-rich ices and thermally or non-thermally evaporate with\nCH3OH, we have identified three sight-lines in the Serpens core - SMM1, SMM4\nand SMM4-W - which are likely to be rich in complex organics. Using the IRAM\n30m telescope, narrow lines (FWHM of 1-2 km s-1) of CH3CHO and CH3OCH3 are\ndetected toward all sources, HCOOCH3 toward SMM1 and SMM4-W, and C2H5OH not at\nall. Beam-averaged abundances of individual complex organics range between 0.6\nand 10% with respect to CH3OH when the CH3OH rotational temperature is applied.\nThe summed complex organic abundances also vary by an order of magnitude, with\nthe richest chemistry toward the most luminous protostar SMM1. The range of\nabundances compare well with other beam-averaged observations of low-mass\nsources. Complex organic abundances are of the same order of magnitude toward\nlow-mass protostars and high-mass hot cores, but HCOOCH3 is relatively more\nimportant toward low-mass protostars. This is consistent with a sequential ice\nphotochemistry, dominated by CHO-containing products at low temperatures and\nearly times.", "positive": "Reaching for the stars -- JWST/NIRSpec spectroscopy of a lensed star\n candidate at $z=4.76$: We present JWST/NIRSpec observations of a highly magnified star candidate at\na photometric redshift of $z_{\\mathrm{phot}}\\simeq4.8$, previously detected in\nJWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015\n($z=0.591$). The spectroscopic observation allows us to precisely measure the\nredshift of the host arc at $z_{\\mathrm{spec}}=4.758\\pm0.004$, and the star's\nspectrum displays clear Lyman- and Balmer-breaks commensurate with this\nredshift. A fit to the spectrum suggests a B-type super-giant star of surface\ntemperature $T_{\\mathrm{eff,B}}\\simeq15000$ K with either a redder F-type\ncompanion ($T_{\\mathrm{eff,F}}\\simeq6250$K) or significant dust attenuation\n($A_V\\simeq0.82$) along the line of sight. We also investigate the possibility\nthat this object is a magnified young globular cluster rather than a single\nstar. We show that the spectrum is in principle consistent with a star cluster,\nwhich could also accommodate the lack of flux variability between the two\nepochs. However, the lack of a counter image and the strong upper limit on the\nsize of the object from lensing symmetry, $r\\lesssim0.5$ pc, could indicate\nthat this scenario is somewhat less likely -- albeit not completely ruled out\nby the current data. The presented spectrum seen at a time when the Universe\nwas only $\\sim1.2$ Gyr old showcases the ability of JWST to study early stars\nthrough extreme lensing." }, { "anchor": "Galaxy And Mass Assembly (GAMA): mass-size relations of z$<$0.1 galaxies\n subdivided by S\u00e9rsic index, colour and morphology: We use data from the Galaxy And Mass Assembly (GAMA) survey in the redshift\nrange 0.01$<$z$<$0.1 (8399 galaxies in $g$ to $K_s$ bands) to derive the\nstellar mass $-$ half-light radius relations for various divisions of 'early'\nand 'late'-type samples. We find the choice of division between early and late\n(i.e., colour, shape, morphology) is not particularly critical, however, the\nadopted mass limits and sample selections (i.e., the careful rejection of\noutliers and use of robust fitting methods) are important. In particular we\nnote that for samples extending to low stellar mass limits\n($<10^{10}\\mathcal{M_{\\odot}}$) the S\\'ersic index bimodality, evident for high\nmass systems, becomes less distinct and no-longer acts as a reliable separator\nof early- and late-type systems. The final set of stellar mass $-$ half-light\nradius relations are reported for a variety of galaxy population subsets in 10\nbands ($ugrizZYJHK_s$) and are intended to provide a comprehensive low-z\nbenchmark for the many ongoing high-z studies. Exploring the variation of the\nstellar mass $-$ half-light radius relations with wavelength we confirm earlier\nfindings that galaxies appear more compact at longer wavelengths albeit at a\nsmaller level than previously noted: at $10^{10}\\mathcal{M_{\\odot}}$ both\nspiral systems and ellipticals show a decrease in size of 13% from $g$ to $K_s$\n(which is near linear in log wavelength). Finally we note that the sizes used\nin this work are derived from 2D S\\'ersic light profile fitting (using\nGALFIT3), i.e., elliptical semi-major half light radii, improving on earlier\nlow-z benchmarks based on circular apertures.", "positive": "Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a\n pilot study of molecular and atomic gas at z~0.2: An understanding of the mass build-up in galaxies over time necessitates\ntracing the evolution of cold gas (molecular and atomic) in galaxies. To that\nend, we have conducted a pilot study called CO Observations with the LMT of the\nBlind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23\ngalaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z\n= 0.206), where 12 are cluster members and 11 are slightly in the foreground or\nbackground, using about 28 total hours on the Redshift Search Receiver (RSR) on\nthe Large Millimeter Telescope (LMT) to measure the $^{12}$CO J = 1 --> 0\nemission line and obtain molecular gas masses. These new observations provide a\nunique opportunity to probe both the molecular and atomic components of\ngalaxies as a function of environment beyond the local Universe. For our sample\nof 23 galaxies, nine have reliable detections (S/N$\\geq$3.6) of the $^{12}$CO\nline, and another six have marginal detections (2.0 < S/N < 3.6). For the\nremaining eight targets we can place upper limits on molecular gas masses\nroughly between $10^9$ and $10^{10} M_\\odot$. Comparing our results to other\nstudies of molecular gas, we find that our sample is significantly more\nabundant in molecular gas overall, when compared to the stellar and the atomic\ngas component, and our median molecular gas fraction lies about $1\\sigma$ above\nthe upper limits of proposed redshift evolution in earlier studies. We discuss\npossible reasons for this discrepancy, with the most likely conclusion being\ntarget selection and Eddington bias." }, { "anchor": "Pa$\u03b2$, H$\u03b1$, and Attenuation in NGC 5194 and NGC 6946: We combine Hubble Space Telescope (HST) Paschen $\\beta$ (Pa$\\beta$) imaging\nwith ground-based, previously published H$\\alpha$ maps to estimate the\nattenuation affecting H$\\alpha$, A(H$\\alpha$), across the nearby, face-on\ngalaxies NGC 5194 and NGC 6946. We estimate A(H$\\alpha$) in ~ 2,000 independent\n2\" ~75 pc diameter apertures in each galaxy, spanning out to a galactocentric\nradius of almost 10 kpc. In both galaxies, A(H$\\alpha$) drops with radius, with\na bright, high attenuation inner region, though in detail the profiles differ\nbetween the two galaxies. Regions with the highest attenuation-corrected\nH$\\alpha$ luminosity show the highest attenuation, but the observed H$\\alpha$\nluminosity of a region is not a good predictor of attenuation in our data.\nConsistent with much previous work, the IR-to-H$\\alpha$ color does a good job\nof predicting A(H$\\alpha$). We calculate the best-fit empirical coefficients\nfor use combining H$\\alpha$ with 8, 12, 24, 70, or 100 $\\mu$m to correct for\nattenuation. These agree well with previous work but we also measure\nsignificant scatter around each of these linear relations. The local atomic\nplus molecular gas column density, N(H), also predicts A(H$\\alpha$) well. We\nshow that a screen with magnitude ~ 0.2 times the expected for a Milky Way\ngas-to-dust value does a reasonable job of explaining A(H$\\alpha$) as a\nfunction of N(H). This could be expected if only ~ 40% of gas and dust directly\noverlap regions of H$\\alpha$ emission.", "positive": "NGC 4102: High Resolution Infrared Observations of a Nuclear Starburst\n Ring: The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We\nmapped NGC 4102 in the 12.8 micron line of [NeII], using the echelon\nspectrometer TEXES on the NASA IRTF, to obtain a data cube with 1.5\" spatial\nand 25 km/s spectral, resolution. Combining near-infrared, radio, and the\n[NeII] data shows that the extinction to the starburst is substantial, more\nthan 2 magnitudes at K band, and that the neon abundance is less than half\nsolar. We find that the star formation in the nuclear region is confined to a\nrotating ring or disk of 4.3\" (~300 pc) diameter, inside the Inner Lindblad\nResonance. This region is an intense concentration of mass, with a dynamical\nmass of ~3 x 10^9 solar masses, and of star formation. The young stars in the\nring produce the [NeII] flux reported by Spitzer for the entire galaxy. The\nmysterious blue component of line emission detected in the near-infrared is\nalso seen in [NeII]; it is not a normal AGN outflow." }, { "anchor": "Local Group dSph radio survey with ATCA (I): Observations and background\n sources: Dwarf spheroidal (dSph) galaxies are key objects in near-field cosmology,\nespecially in connection to the study of galaxy formation and evolution at\nsmall scales. In addition, dSphs are optimal targets to investigate the nature\nof dark matter. However, while we begin to have deep optical photometric\nobservations of the stellar population in these objects, little is known so far\nabout their diffuse emission at any observing frequency, and hence on thermal\nand non-thermal plasma possibly residing within dSphs. In this paper, we\npresent deep radio observations of six local dSphs performed with the Australia\nTelescope Compact Array at 16 cm wavelength. We mosaiced a region of radius of\nabout one degree around three \"classical\" dSphs, Carina, Fornax, and Sculptor,\nand of about half of degree around three \"ultra-faint\" dSphs, BootesII, Segue2,\nand Hercules. The rms noise level is below 0.05 mJy for all the maps. The\nrestoring beams FWHM ranged from 4.2 x 2.5 arcseconds to 30.0 x 2.1 arcseconds\nin the most elongated case. A catalogue including the 1392 sources detected in\nthe six dSph fields is reported. The main properties of the background sources\nare discussed, with positions and fluxes of brightest objects compared with the\nFIRST, NVSS, and SUMSS observations of the same fields. The observed population\nof radio emitters in these fields is dominated by synchrotron sources. We\ncompute the associated source number counts at 2 GHz down to fluxes of 0.25\nmJy, which prove to be in agreement with AGN count models.", "positive": "Testing Newtonian Gravity with AAOmega: Mass-to-Light Profiles of Four\n Globular Clusters: Testing Newtonian gravity in the weak-acceleration regime is vital to our\nunderstanding of the nature of the gravitational interaction. It has recently\nbeen claimed that the velocity dispersion profiles of several globular clusters\nflatten out at large radii, reminiscent of galaxy rotation curves, even though\nglobular clusters are thought to contain little or no dark matter. We\ninvestigate this claim, using AAOmega observations of four globular clusters,\nnamely M22, M30, M53 and M68. M30, one such cluster that has had this claim\nmade for its velocity dispersion, was included for comparison with previous\nstudies. We find no statistically significant flattening of the velocity\ndispersion at large radii for any of our target clusters and therefore we infer\nthe observed dynamics do not require that globular clusters are dark matter\ndominated, or a modification of gravity. Furthermore, by applying a simple\ndynamical model we determine the radial mass-to-light profiles for each\ncluster. The isothermal rotations of each cluster are also measured, with M22\nexhibiting clear rotation, M68 possible rotation and M30 and M53 lacking any\nrotation, within the uncertainties." }, { "anchor": "ALMA spectroscopic survey in the Hubble Ultra Deep Field: CO luminosity\n functions and the evolution of the cosmic density of molecular gas: In this paper we use ASPECS, the ALMA Spectroscopic Survey in the {\\em\nHubble} Ultra Deep Field (UDF) in band 3 and band 6, to place blind constraints\non the CO luminosity function and the evolution of the cosmic molecular gas\ndensity as a function of redshift up to $z\\sim 4.5$. This study is based on\ngalaxies that have been solely selected through their CO emission and not\nthrough any other property. In all of the redshift bins the ASPECS measurements\nreach the predicted `knee' of the CO luminosity function (around\n$5\\times10^{9}$ K km/s pc$^2$). We find clear evidence of an evolution in the\nCO luminosity function with respect to $z\\sim 0$, with more CO luminous\ngalaxies present at $z\\sim 2$. The observed galaxies at $z\\sim 2$ also appear\nmore gas-rich than predicted by recent semi-analytical models. The comoving\ncosmic molecular gas density within galaxies as a function of redshift shows a\nfactor 3-10 drop from $z \\sim 2$ to $z \\sim 0$ (with significant error bars),\nand possibly a decline at $z>3$. This trend is similar to the observed\nevolution of the cosmic star formation rate density. The latter therefore\nappears to be at least partly driven by the increased availability of molecular\ngas reservoirs at the peak of cosmic star formation ($z\\sim2$).", "positive": "Comparisons of the Interstellar Magnetic Field Directions obtained from\n the IBEX Ribbon and Interstellar Polarizations: Variations in the spatial configuration of the interstellar magnetic field\n(ISMF) near the Sun can be constrained by comparing the ISMF direction at the\nheliosphere found from the Interstellar Boundary Explorer spacecraft (IBEX)\nobservations of a 'Ribbon' of energetic neutral atoms (ENAs), with the ISMF\ndirection derived from optical polarization data for stars within ~40 pc. Using\ninterstellar polarization observations towards ~30 nearby stars within 90 deg\nof the heliosphere nose, we find that the best fits to the polarization\nposition angles are obtained for a magnetic pole directed towards ecliptic\ncoordinates of lambda, beta 263 deg, 37 deg (or galactic coordinates of L,B 38\ndeg, 23deg), with uncertainties of +/- 35 deg, based on the broad minimum of\nthe best fits and the range of data quality. This magnetic pole is 33 deg from\nthe magnetic pole that is defined by the center of the arc of the ENA Ribbon.\nThe IBEX ENA ribbon is seen in sightlines that are perpendicular to the ISMF as\nit drapes over the heliosphere. The similarity of the polarization and Ribbon\ndirections for the local ISMF suggest that the local field is coherent over\nscale sizes of tens of parsecs. The ISMF vector direction is nearly\nperpendicular to the flow of local ISM through the local standard of rest,\nsupporting a possible local ISM origin related to an evolved expanding\nmagnetized shell. The local ISMF direction is found to have a curious geometry\nwith respect to the cosmic microwave background dipole moment." }, { "anchor": "Light element variations within the different age-metallicity\n populations in the nucleus of the Sagittarius dwarf: The cluster M54 lies at the centre of the Sagittarius dwarf spheroidal\ngalaxy, and therefore may be the closest example of a nuclear star cluster.\nEither in-situ star formation, inspiralling globular clusters, or a combination\nhave been invoked to explain the wide variety of stellar sub-populations in\nnuclear star clusters. Globular clusters are known to exhibit light element\nvariations, which can be identified using the photometric construct called a\nchromosome map. In this letter, we create chromosome maps for three distinct\nage-metallicity sub-populations in the vicinity of M54. We find that the old,\nmetal-poor population shows the signature of light element variations, while\nthe young and intermediate-age metal rich populations do not. We conclude that\nthe nucleus of Sagittarius formed through a combination of in-situ star\nformation and globular cluster accretion. This letter demonstrates that\nproperly constructed chromosome maps of iron-complex globular clusters can\nprovide insight into the formation locations of the different stellar\npopulations.", "positive": "SIRIUS project. I. Star formation models for star-by-star simulations of\n star clusters and galaxy formation: Most stars are formed as star clusters in galaxies, which then disperse into\ngalactic disks. Upcoming exascale supercomputational facilities will enable\nperforming simulations of galaxies and their formation by resolving individual\nstars (star-by-star simulations). This will substantially advance our\nunderstanding of star formation in galaxies, star cluster formation, and\nassembly histories of galaxies. In previous galaxy simulations, a simple\nstellar population approximation was used. It is, however, difficult to improve\nthe mass resolution with this approximation. Therefore, a model for forming\nindividual stars that can be used in simulations of galaxies must be\nestablished. In this first paper of a series of the SIRIUS (SImulations\nResolving IndividUal Stars) project, we demonstrate a stochastic star formation\nmodel for star-by-star simulations. An assumed stellar initial mass function\n(IMF) is randomly assigned to newly formed stars. We introduce a maximum search\nradius to assemble the mass from surrounding gas particles to form star\nparticles. In this study, we perform a series of N-body/smoothed particle\nhydrodynamics simulations of star cluster formations from turbulent molecular\nclouds and ultra-faint dwarf galaxies as test cases. The IMF can be correctly\nsampled if a maximum search radius that is larger than the value estimated from\nthe threshold density for star formation is adopted. In small clouds, the\nformation of massive stars is highly stochastic because of the small number of\nstars. We confirm that the star formation efficiency and threshold density do\nnot strongly affect the results. We find that our model can naturally reproduce\nthe relationship between the most massive stars and the total stellar mass of\nstar clusters. Herein, we demonstrate that our models can be applied to\nsimulations varying from star clusters to galaxies for a wide range of\nresolutions." }, { "anchor": "Metallicity Distribution Function of the Eridanus~II Ultra-Faint Dwarf\n Galaxy from Hubble Space Telescope Narrow-band Imaging: We use deep narrowband Ca H&K ($F395N$) imaging taken with the Hubble Space\nTelescope (HST) to construct the metallicity distribution function (MDF) of\nLocal Group (LG) ultra-faint dwarf (UFD) galaxy Eridanus II (Eri II). When\ncombined with archival $F475W$ and $F814W$ data, we measure metallicities for\n60 resolved red giant branch stars as faint as $m_{F475W}\\sim24$ mag, a factor\nof $\\sim4$x more stars than current spectroscopic MDF determinations. We find\nthat Eri II has a mean metallicity of [Fe/H]$=$-2.50$^{+0.07}_{-0.07}$ and a\ndispersion of $\\sigma_{\\mbox{[Fe/H]}}=0.42^{+0.06}_{-0.06}$, which are\nconsistent with spectroscopic MDFs, though more precisely constrained owing to\na larger sample. We identify a handful of extremely metal-poor star candidates\n(EMP; [Fe/H] $< -3$) that are marginally bright enough for spectroscopic follow\nup. Eri II's MDF appears well-described by a leaky box chemical evolution\nmodel. We also compute an updated orbital history for Eri II using Gaia eDR3\nproper motions, and find that it is likely on first infall into the Milky Way.\nOur findings suggest that Eri II underwent an evolutionary history similar to\nthat of an isolated galaxy. Compared to MDFs for select cosmological\nsimulations of similar mass galaxies, we find that Eri II has a lower fraction\nof stars with [Fe/H] $< -3$, though such comparisons should currently be\ntreated with caution due to a paucity of simulations, selection effects, and\nknown limitations of Ca H&K for EMPs. This study demonstrates the power of deep\nHST CaHK imaging for measuring the MDFs of UFDs.", "positive": "Candidate planetary nebulae in the IPHAS photometric catalogue: Context. We have carried out a semi-automated search for planetary nebulae\n(PNe) in the INT Photometric H-Alpha Survey (IPHAS) catalogue. We present the\nPN search and the list of selected candidates. We cross correlate the selected\ncandidates with a number of existing infrared galactic surveys in order to gain\nfurther insight into the nature of the candidates. Spectroscopy of a subset of\nobjects is used to estimate the number of PNe present in the entire candidate\nlist.\n Aims. The overall aim of the IPHAS PN project is to carry out a deep census\nof PNe in the northern Galactic plane, an area where PN detections are clearly\nlacking.\n Methods. The PN search is carried out on the IPHAS photometric catalogues.\nThe candidate selection is based on the IPHAS and 2MASS/UKIDSS colours of the\nobjects and the final candidate selection is made visually.\n Results. From the original list of ~600 million IPHAS detections we have\nselected a total of 1005 objects. Of these, 224 are known objects, leaving us\nwith 781 PN candidates. Based on the initial follow-up spectroscopy, we expect\nthe list to include very young and proto-PNe in addition to genuine, normal PNe\n(~16 %) and emission line objects other than PNe. We present additional\ncriteria to select the most probable PN candidates from our candidate list." }, { "anchor": "CO multi-line observations of HH 80-81: a two-component molecular\n outflow associated with the largest protostellar jet in our Galaxy: Stretching a length reaching 10 pc projected in the plane of sky, the radio\njet associated with Herbig-Haro objects 80 and 81 (HH 80-81) is known as the\nlargest and best collimated protostellar jet in our Galaxy. The nature of the\nmolecular outflow associated with this extraordinary jet remains an unsolved\nquestion which is of great interests to our understanding of the relationship\nbetween jets and outflows in high-mass star formation. Here we present Atacama\nPathfinder EXperiment CO(6-5) and (7-6), James Clerk Maxwell Telescope CO(3-2),\nCaltech Submillimeter Observatory CO(2-1), and Submillimeter Array CO and\n$^{13}$CO(2-1) mapping observations of the outflow. We report on the detection\nof a two-component outflow consisting of a collimated component along the jet\npath and a wide-angle component with an opening angle of about $30^{\\circ}$.\nThe gas velocity structure suggests that each of the two components traces part\nof a primary wind. From LVG calculations of the CO lines, the outflowing gas\nhas a temperature around 88 K, indicating that the gas is being heated by\nshocks. Based on the CO(6-5) data, the outflow mass is estimated to be a few\n$M_{\\odot}$, which is dominated by the wide-angle component. A comparison\nbetween the HH 80-81 outflow and other well shaped massive outflows suggests\nthat the opening angle of massive outflows continues to increase over time.\nTherefore, the mass loss process in the formation of early-B stars seems to be\nsimilar to that in low-mass star formation, except that a jet component would\ndisappear as the central source evolves to an ultracompact HII region.", "positive": "Fluorine Abundances in the Galactic Nuclear Star Cluster: Abundances of fluorine ($^{19}$F), as well as isotopic ratios of\n$^{16}$O/$^{17}$O, are derived in a sample of luminous young\n($\\sim$10$^{7}$--10$^{8}$ yrs) red giants in the Galactic center (with\ngalactocentric distances ranging from 0.6--30 pc), using high-resolution\ninfrared spectra and vibration-rotation lines of H$^{19}$F near\n$\\lambda$2.3$\\mu$m. Five of the six red giants are members of the Nuclear star\ncluster that orbits the central supermassive black hole. Previous\ninvestigations of the chemical evolution of $^{19}$F in Galactic thin and thick\ndisk stars have revealed that the nucleosynthetic origins of $^{19}$F may be\nrather complex, resulting from two, or more, astrophysical sites; fluorine\nabundances behave as a primary element with respect to Fe abundances for thick\ndisk stars and as a secondary element in thin disk stars. The Galactic center\nred giants analyzed fall within the thin disk relation of F with Fe, having\nnear-solar, to slightly larger, abundances of Fe ($<$[Fe/H]$>$=+0.08$\\pm$0.04),\nwith a slight enhancement of the F/Fe abundance ratio\n($<$[F/Fe]$>$=+0.28$\\pm$0.17). In terms of their F and Fe abundances, the\nGalactic center stars follow the thin disk population, which requires an\nefficient source of $^{19}$F that could be the winds from core-He burning Wolf\nRayet stars, or thermally-pulsing AGB stars, or a combination of both. The\nobserved increase of [F/Fe] with increasing [Fe/H] found in thin disk and\nGalactic center stars is not predicted by any published chemical evolution\nmodels that are discussed, thus a quantitative understanding of yields from the\nvarious possible sources of $^{19}$F remains unknown." }, { "anchor": "A revised view of the Canis Major stellar overdensity with DECam and\n Gaia: new evidence of a stellar warp of blue stars: We present DECam imaging combined with Gaia DR2 data to study the Canis Major\noverdensity. The presence of the so-called Blue Plume stars in a low-pollution\narea of the color-magnitude diagram allows us to derive the distance and proper\nmotions of this stellar feature along the line of sight of its hypothetical\ncore. The stellar overdensity extends on a large area of the sky at low\nGalactic latitudes, below the plane, and between 230$^\\circ < \\ell <\n255^\\circ$. According to the orbit derived for Canis Major, it presents an\non-plane rotation around the Milky Way. Moreover, additional overdensities of\nBlue Plume stars are found around the plane and across the Galaxy, proving that\nthese objects are not only associated with that structure. The spatial\ndistribution of these stars, derived using Gaia astrometric data, confirms that\nthe detection of the Canis Major overdensity results more from the warped\nstructure of the Milky Way disk than from the accretion of a dwarf galaxy.", "positive": "The signatures of the resonances of a large Galactic bar in local\n velocity space: The second data release of the Gaia mission has revealed a very rich\nstructure in local velocity space. In terms of in-plane motions, this rich\nstructure is also seen as multiple ridges in the actions of the axisymmetric\nbackground potential of the Galaxy. These ridges are probably related to a\ncombination of effects from ongoing phase-mixing and resonances from the spiral\narms and the bar. We have recently developed a method to capture the behaviour\nof the stellar phase-space distribution function at a resonance, by\nre-expressing it in terms of a new set of canonical actions and angles\nvariables valid in the resonant region. Here, by properly treating the\ndistribution function at resonances, and by using a realistic model for a\nslowly rotating large Galactic bar with pattern speed 39 km/s/kpc, we show that\nno less than six ridges in local action space can be related to resonances with\nthe bar. Two of these at low angular momentum correspond to the corotation\nresonance, and can be associated to the Hercules moving group in local velocity\nspace. Another one at high angular momentum corresponds to the outer Lindblad\nresonance, and can tentatively be associated to the velocity structure seen as\nan arch at high azimuthal velocities in Gaia data. The other ridges are\nassociated to the 3:1, 4:1 and 6:1 resonances. The latter can be associated to\nthe so-called 'horn' of the local velocity distribution. While it is clear that\neffects from spiral arms and incomplete phase-mixing related to external\nperturbations also play a role in shaping the complex kinematics revealed by\nGaia data, the present work demonstrates that, contrary to common\nmisconceptions, the bar alone can create multiple prominent ridges in velocity\nand action space." }, { "anchor": "Extragalactic Jets as Probes of Distant Clusters of Galaxies and the\n Clusters Occupied by Bent Radio AGN (COBRA) Survey: We are conducting a large survey of distant clusters of galaxies using radio\nsources with bent jets and lobes as tracers. These radio sources are driven by\nAGN and achieve their bent morphologies through interaction with the\nsurrounding gas found in clusters of galaxies. Based on low-redshift studies,\nthese types of sources can be used to identify clusters very efficiently. We\npresent initial results from our survey of 653 bent-double radio sources with\noptical hosts too faint to appear in the SDSS. The sample was observed in the\ninfrared with Spitzer, and it has revealed $\\sim$200 distant clusters or\nproto-clusters in the redshift range $z\\sim0.7 - 3.0$. The sample of\nbent-doubles contains both quasars and radio galaxies enabling us to study both\nradiative and kinetic mode feedback in cluster and group environments at a wide\nrange of redshifts.", "positive": "Census of young stellar population in the Galactic H II region Sh2-242: We present here identification and characterization of the young stellar\npopulation associated with an active star-forming site Sh2-242. We used our own\nnew optical imaging and spectroscopic observational data, as well as several\narchival catalogs, e.g., Pan-STARRS 1, $Gaia$ DR2, IPHAS, WIRCam, 2MASS, and\n$Spitzer$. Slit spectroscopic results confirm the classification of the main\nionizing source BD+26 980 as an early-type star of spectral type B0.5 V. The\nspectrophotometric distance of the star is estimated as 2.08 $\\pm$ 0.24 kpc,\nwhich confirms the source as a member of the cluster. An extinction map\ncovering a large area (diameter $\\sim$ 50') is generated with $H$ and $K$\nphotometry toward the region. From the map, three distinct locations of peak\nextinction complexes ($A_{V}$ $\\simeq$ 7$-$17 mag) are identified for the very\nfirst time. Using the infrared color excess, a total of 33 Class I and 137\nClass II young objects are classified within the region. The IPHAS photometry\nreveals classification of 36 H$\\alpha$ emitting sources, which might be class\nII objects. Among 36 H$\\alpha$ emitting sources, 5 are already identified using\ninfrared excess emission. In total, 201 young objects are classified toward\nS242 from this study. The membership status of the young sources is further\nwindowed with the inclusion of parallax from the $Gaia$ DR2 catalog. Using the\noptical and infrared color-magnitude diagrams, the young stellar objects are\ncharacterized with an average age of $\\sim$ 1 Myr and the masses in the range\n0.1$-$3.0 $M_\\odot$. The census of the stellar content within the region is\ndiscussed using combined photometric and spectroscopic data." }, { "anchor": "The physical properties and the evolution of the interacting system\n AM1204-292: We investigate the interaction effects in the stellar and gas kinematics,\nstellar population and ionized gas properties in the interacting galaxy pair\nAM1209-292, composed by NGC4105 and NGC4106. The data consist of long-slit\nspectra in the range of 3000-7050 {\\AA}. The massive E3 galaxy NGC4105 presents\na flat stellar velocity profile, while the ionized gas is in strong rotation,\nsuggesting external origin. Its companion, NGC4106, shows asymmetries in the\nradial velocity field, likely due to the interaction. The dynamics of the\ninteracting pair was modeled using P-Gadget3 TreePM/SPH code, from which we\nshow that the system has just passed the first perigalacticum, which triggered\nan outbreak of star formation, currently at full maximum. We characterized the\nstellar population properties using the stellar population synthesis code\nSTARLIGHT and, on average, both galaxies are predominantly composed of old\nstellar populations. NGC4105 has a slightly negative age gradient, comparable\nto that of the most massive elliptical galaxies, but a steeper metallicity\ngradient. The SB0 galaxy NGC4106 presents smaller radial variations in both age\nand metallicity in comparison with intermediate mass early-type galaxies. These\ngradients have not been disturbed by the interaction since the star formation\nhappened very recently and was not extensive in mass. Electron density\nestimates for the pair are systematically higher than those obtained in\nisolated galaxies. The central O/H abundances were obtained from\nphotoionization models in combination with emission line ratios, which resulted\nin 12+log(O/H)=9.03+/-0.02 and 12+log(O/H)=8.69+/-0.05 for NGC4105 and NGC4106,\nrespectively.", "positive": "On the dependence of galaxy morphologies on galaxy mergers: The distribution of galaxy morphological types is a key test for models of\ngalaxy formation and evolution, providing strong constraints on the relative\ncontribution of different physical processes responsible for the growth of the\nspheroidal components. In this paper, we make use of a suite of semi-analytic\nmodels to study the efficiency of galaxy mergers in disrupting galaxy discs and\nbuilding galaxy bulges. In particular, we compare standard prescriptions\nusually adopted in semi-analytic models, with new prescriptions proposed by\nKannan et al., based on results from high-resolution hydrodynamical\nsimulations, and we show that these new implementations reduce the efficiency\nof bulge formation through mergers. In addition, we compare our model results\nwith a variety of observational measurements of the fraction of\nspheroid-dominated galaxies as a function of stellar and halo mass, showing\nthat the present uncertainties in the data represent an important limitation to\nour understanding of spheroid formation. Our results indicate that the main\ntension between theoretical models and observations does not stem from the\nsurvival of purely disc structures (i.e. bulgeless galaxies), rather from the\ndistribution of galaxies of different morphological types, as a function of\ntheir stellar mass." }, { "anchor": "Star Formation and Relaxation in 379 Nearby Galaxy Clusters: We investigate the relationship between star formation (SF) and level of\nrelaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the\nSloan Digital Sky Survey to measure cluster membership and level of relaxation,\nand to select star-forming galaxies based on mid-infrared emission detected\nwith the Wide-Field Infrared Survey Explorer. For galaxies with absolute\nmagnitudes M_r < -19.5, we find an inverse correlation between SF fraction and\ncluster relaxation: as a cluster becomes less relaxed, its SF fraction\nincreases. Furthermore, in general, the subtracted SF fraction in all unrelaxed\nclusters (0.117 +/- 0.003) is higher than that in all relaxed clusters (0.097\n+/- 0.005). We verify the validity of our SF calculation methods and membership\ncriteria through analysis of previous work. Our results agree with previous\nfindings that a weak correlation exists between cluster SF and dynamical state,\npossibly because unrelaxed clusters are less evolved relative to relaxed\nclusters.", "positive": "Small-scale Intensity Mapping: Extended Ly$\u03b1$, H$\u03b1$ and\n Continuum emission as a Probe of Halo Star Formation in High-redshift\n Galaxies: Lyman alpha halos are observed ubiquitously around star-forming galaxies at\nhigh redshift, but their origin is still a matter of debate. We demonstrate\nthat the emission from faint unresolved satellite sources, $M_{\\rm UV} \\gtrsim\n-17$, clustered around the central galaxies may play a major role in generating\nspatially extended Ly$\\alpha$, continuum (${\\rm UV + VIS}$) and H$\\alpha$\nhalos. We apply the analytic formalism developed in Mas-Ribas & Dijkstra (2016)\nto model the halos around Lyman Alpha Emitters (LAEs) at $z=3.1$, for several\ndifferent satellite clustering prescriptions. In general, our UV and Ly$\\alpha$\nsurface brightness profiles match the observations well at $20\\lesssim r\n\\lesssim 40$ physical kpc from the centers of LAEs. We discuss how our profiles\ndepend on various model assumptions and how these can be tested and constrained\nwith future H$\\alpha$ observations by the James Webb Space Telescope (JWST).\nOur analysis shows how spatially extended halos constrain (i) the presence of\notherwise undetectable satellite sources, (ii) the integrated, volumetric\nproduction rates of Ly$\\alpha$ and LyC photons, and (iii) their\npopulation-averaged escape fractions. These quantities are all directly\nrelevant for understanding galaxy formation and evolution and, for high enough\nredshifts, cosmic reionization." }, { "anchor": "The Differential Size Growth of Field and Cluster Galaxies at z=2.1\n Using the ZFOURGE Survey: There is ongoing debate regarding the extent that environment affects galaxy\nsize growth beyond z>1. To investigate the differences in star-forming and\nquiescent galaxy properties as a function of environment at z=2.1, we create a\nmass-complete sample of 59 cluster galaxies Spitler et al. (2012) and 478 field\ngalaxies with log(M)>9 using photometric redshifts from the ZFOURGE survey. We\ncompare the mass-size relation of field and cluster galaxies using measured\ngalaxy semi-major axis half-light radii ($r_{1/2,maj}$) from CANDELS HST/F160W\nimaging. We find consistent mass normalized (log(M)=10.7) sizes for quiescent\nfield galaxies ($r_{1/2,maj}=1.81\\pm0.29$ kpc) and quiescent cluster galaxies\n($r_{1/2,maj}=2.17\\pm0.63$ kpc). The mass normalized size of star-forming\ncluster galaxies ($r_{1/2,maj}=4.00\\pm0.26$ kpc ) is 12% larger (KS test\n$2.1\\sigma$) than star-forming field galaxies ($r_{1/2,maj}=3.57\\pm0.10$ kpc).\nFrom the mass-color relation we find that quiescent field galaxies with\n9.710.4\nhave consistent colors. We find that star-forming cluster galaxies are on\naverage 20% redder than star-forming field galaxies at all masses. Furthermore,\nwe stack galaxy images to measure average radial color profiles as a function\nof mass. Negative color gradients are only present for massive star-forming\nfield and cluster galaxies with log(M)>10.4, the remaining galaxy masses and\ntypes have flat profiles. Our results suggest given the observed differences in\nsize and color of star-forming field and cluster galaxies, that the environment\nhas begun to influence/accelerate their evolution. However, the lack of\ndifferences between field and cluster quiescent galaxies indicates that the\nenvironment has not begun to significantly influence their evolution at z~2.", "positive": "DustPedia - the relationships between stars, gas and dust for galaxies\n residing in different environments: We use a sub-set of the DustPedia galaxy sample (461 galaxies) to investigate\nthe effect the environment has had on galaxies. We consider Virgo cluster and\nfield samples and also assign a density contrast parameter to each galaxy, as\ndefined by the local density of SDSS galaxies. We consider their chemical\nevolution (using M_{Dust}/M_{Baryon} and M_{Gas}/M_{Baryon}), their specific\nstar formation rate (SFR/M_{Stars}), star formation efficiency (SFR/M_{Gas}),\nstars-to-dust mass ratio (M_{Stars}/M_{Dust}), gas-to-dust mass ratio\n(M_{Gas}/M_{Dust}) and the relationship between star formation rate per unit\nmass of dust and dust temperature (SFR/M_{Dust} and T_{Dust}). Late type\ngalaxies (later than Sc) in all of the environments can be modelled using\nsimple closed box chemical evolution and a simple star formation history\n(SFR(t) \\propto t\\exp{-t/\\tau}). For earlier type galaxies the physical\nmechanisms that give rise to their properties are clearly much more varied and\nrequire a more complicated model (mergers, gas in or outflow). However, we find\nlittle or no difference in the properties of galaxies of the same morphological\ntype within the cluster, field or with different density contrasts. It appears\nthat it is morphology, how and whenever this is laid down, and consistent\ninternal physical processes that primarily determine the derived properties of\ngalaxies in the DustPedia sample and not processes related to differences in\nthe local environment." }, { "anchor": "An Imaging Spectroscopic Survey of the Planetary Nebula NGC 7009 with\n MUSE: The spatial structure of the emission lines and continuum over the 50\narcsecond extent of the nearby, O-rich, planetary nebula NGC 7009 (Saturn\nNebula) have been observed with the MUSE integral field spectrograph on the ESO\nVery Large Telescope. Science Verification data, in <0.6 arcsecond seeing, have\nbeen reduced and analysed as images over the wavelength range 4750-9350A.\nEmission line maps over the bright shells are presented, from neutral to the\nhighest ionization available (He II and [Mn V]). For collisionally excited\nlines (CELs), maps of electron temperature (T_e from [N II] and [S III]) and\nelectron density (N_e from [S II] and [Cl III]) are available and for optical\nrecombination lines (ORLs) temperature (from the Paschen jump and ratio of He I\nlines) and density (from high Paschen lines). These estimates are compared: for\nthe first time, maps of the differences in CEL and ORL T_e's have been derived,\nand correspondingly a map of t^2 between a CEL and ORL temperature, showing\nconsiderable detail. Total abundances of He and O were formed, the latter using\nthree ionization correction factors. However the map of He/H is not flat,\ndeparting by ~2% from a constant value, with remnants corresponding to\nionization structures. Ionization correction factor methods are compared for O\nabundance, but none delivers a flat map. An integrated spectrum over an area of\n2340 square arcseconds was also formed and compared to 1D photoionization\nmodels. The spatial variation of a range of nebular parameters illustrates the\ncomplexity of the ionized media in NGC 7009. These MUSE data are very rich with\ndetections of many lines over areas of hundreds of square arcseconds and\nfollow-on studies are indicated. (Abridged)", "positive": "Evidence for gravitational quadrupole moment variations in the companion\n of PSR J2051-0827: We have conducted radio timing observations of the eclipsing millisecond\nbinary pulsar J2051-0827 with the European Pulsar Timing Array network of\ntelescopes and the Parkes radio telescope, spanning over 13 years. The\nincreased data span allows significant measurements of the orbital\neccentricity, e = (6.2 {\\pm} 1.3) {\\times} 10^{-5} and composite proper motion,\n{\\mu}_t = 7.3 {\\pm} 0.4 mas/yr. Our timing observations have revealed secular\nvariations of the projected semi-major axis of the pulsar orbit which are much\nmore extreme than those previously published; and of the orbital period of the\nsystem. Investigation of the physical mechanisms producing such variations\nconfirm that the variations of the semi-major axis are most probably caused by\nclassical spin-orbit coupling in the binary system, while the variations in\norbital period are most likely caused by tidal dissipation leading to changes\nin the gravitational quadrupole moment of the companion." }, { "anchor": "The Long and the Short of It: The Benefits and Leverage of\n Ultraviolet-Radio Galaxy Fitting: Traditionally, the far ultraviolet (FUV) to far-infrared (FIR) and radio\nspectral energy distributions (SEDs) of galaxies have been considered\nseparately despite the common physical process shaping them. In this work, we\nexplore the utility of simultaneously fitting FUV-radio SEDs using an extended\nversion of the ProSpect SED fitting code considering contributions from both\nfree-free and synchrotron emission. We use a small sample of galaxies from the\nDeep Extragalactic VIsible Legacy Survey (DEVILS) and the Key Insights on\nNearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH) where\nhigh-quality and robust FUV-radio data are available to provide an ideal sample\nfor testing a radio extension of ProSpect. As the parameterisation of the radio\nextension links the radio continuum to the FIR emission, we explore the benefit\nof using radio continuum measurements as a constraint on the energy balance\nbetween dust attenuation and emission. We find that for situations where\nMIR-FIR photometry is unavailable, including a 1.4 GHz continuum measurement\nallows for improved accuracy in recovered star formation rates and dust\nluminosities of galaxies reducing the median uncertainty by 0.1 and 0.2 dex\nrespectively. We also demonstrate that incorporating 3 and 10 GHz measurements\nallows for further constraint on the energy balance and therefore the star\nformation rate and dust luminosity. This demonstrates the advantage of\nextending FUV-FIR SED fitting techniques to radio frequencies, especially as we\nmove into an era where FIR surveys will remain limited and radio data become\nabundant (i.e. with the SKA and precursors).", "positive": "CHILES VI: HI and H$\u03b1$ Observations for z < 0.1 Galaxies; Probing\n HI Spin Alignment with Filaments in the Cosmic Web: We present neutral hydrogen (HI) and ionized hydrogen (H${\\alpha}$)\nobservations of ten galaxies out to a redshift of 0.1. The HI observations are\nfrom the first epoch (178 hours) of the COSMOS HI Large Extragalactic Survey\n(CHILES). Our sample is HI biased and consists of ten late-type galaxies with\nHI masses that range from $1.8\\times10^{7}$ M$_{\\odot}$ to $1.1\\times10^{10}$\nM$_{\\odot}$. We find that although the majority of galaxies show irregularities\nin the morphology and kinematics, they generally follow the scaling relations\nfound in larger samples. We find that the HI and H${\\alpha}$ velocities reach\nthe flat part of the rotation curve. We identify the large-scale structure in\nthe nearby CHILES volume using DisPerSE with the spectroscopic catalog from\nSDSS. We explore the gaseous properties of the galaxies as a function of\nlocation in the cosmic web. We also compare the angular momentum vector (spin)\nof the galaxies to the orientation of the nearest cosmic web filament. Our\nresults show that galaxy spins tend to be aligned with cosmic web filaments and\nshow a hint of a transition mass associated with the spin angle alignment." }, { "anchor": "The age of the Milky Way inner stellar spheroid from RR Lyrae population\n synthesis: The central kiloparsecs of the Milky Way are known to host an old, spheroidal\nstellar population, whose spatial and kinematical properties set it apart from\nthe boxy/peanut structure that constitutes most of the central stellar mass.\nThe nature of this spheroidal population, whether a small classical bulge, the\ninnermost stellar halo or a population of disk stars with large initial\nvelocity dispersion, remains unclear. This structure is also a promising\ncandidate to host some of the oldest stars in the Galaxy. Here we address the\ntopic of the inner stellar spheroid age, using spectroscopic and photometric\nmetallicities for a sample of 935 RR Lyrae stars that are constituents of this\ncomponent. By means of stellar population synthesis, we derive an\nage-metallicity relation for RR Lyrae populations. We infer, for the RR Lyrae\nstars in the bulge spheroid, an extremely ancient age of $13.41 \\pm 0.54$ Gyr\nand conclude they were among the first stars to form in what is now the Milky\nWay galaxy. Our age estimate for the central spheroid shows remarkable\nagreement with the age profile that has been inferred for the Milky Way stellar\nhalo, suggesting a connection between the two structures. However, we find mild\nevidence for a transition in the halo properties at $r_{\\rm GC} \\sim 5$~kpc. We\nalso investigate formation scenarios for metal-rich RR Lyrae stars, such as\nbinarity and helium variations, and whether they can provide alternative\nexplanations for the properties of our sample. We conclude that, within our\nframework, the only viable alternative is to have younger, slightly\nhelium-rich, RR Lyrae stars, a hypothesis that would open intriguing questions\nfor the formation of the inner stellar spheroid.", "positive": "High resolution observations of HCN and HCO+ J=3-2 in the disk and\n outflow of Mrk231 -Detection of vibrationally excited HCN in the warped\n nucleus: We obtained high resolution (0.\"25 to 0.\"90) observations of HCN and HCO+\nJ=3-2 of the ultraluminous QSO galaxy Mrk231 with the IRAM Plateau de Bure\nInterferometer. We find luminous HCN and HCO+ 3-2 emission in the main disk and\nwe detect compact (r<90 pc) vibrationally excited HCN 3-2, v2=1f emission\ncentred on the nucleus. The velocity field of the vibrationally excited HCN is\nstrongly inclined (PA=155 deg.) compared to the east-west rotation of the main\ndisk. The nuclear molecular mass is estimated to 8e8 Msun with an average\nN(H2)of 1.2e24 cm-2. Prominent, spatially extended (>350 pc) line wings are\nfound for HCN 3-2 with velocities +-750 km/s. Line ratios indicate that the\nemission is emerging in dense gas n=1e4 - 5e5 cm-3 of elevated HCN abundance\nX(HCN)=1e-8 to 1e-6. High X(HCN) also allows for the emission to originate in\ngas of more moderate density. We tentatively detect nuclear emission from the\nreactive ion HOC+ with HCO+/HOC+=10-20. The HCN v2=1f line emission is\nconsistent with the notion of a hot, dusty, warped inner disk of Mrk231 where\nthe v2=1f line is excited by bright mid-IR 14 micron continuum. We estimate the\nvibrational temperature T_vib to 200-400 K. We propose that 50% of the main HCN\nemission may have its excitation affected by the radiation field through IR\npumping of the vibrational ground state. The HCN emission in the line wings,\nhowever, is more extended and thus likely not strongly affected by IR pumping.\nOur results reveal that dense clouds survive (and/or are formed) in the AGN\noutflow on scales of at least several hundred pc before evaporating or\ncollapsing. The elevated HCN abundance in the outflow is consistent with warm\nchemistry possibly related to shocks and/or X-ray irradiated gas. An upper\nlimit to the mass and momentum flux is 4e8 Msun and 12L_AGN/c, respectively,\nand we discuss possible driving mechanisms for the dense outflow." }, { "anchor": "Life beyond 30: probing the -208$ galaxy candidates based\non their dropout nature in the F115W and/or F150W filters, a high probability\nfor their photometric redshifts, estimated with three different codes, being at\n$z>8$, good fits based on $\\chi^2$ calculations, and predominant solutions\ncompared to $z<8$ alternatives. We find mild evolution in the luminosity\nfunction from $z\\sim13$ to $z\\sim8$, i.e., only a small increase in the average\nnumber density of $\\sim$0.2 dex, while the faint-end slope and absolute\nmagnitude of the knee remain approximately constant, with values\n$\\alpha=-2.2\\pm0.1$ and $M^*=-20.8\\pm0.2$ mag. Comparing our results with the\npredictions of state-of-the-art galaxy evolution models, we find two main\nresults: (1) a slower increase with time in the cosmic star formation rate\ndensity compared to a steeper rise predicted by models; (2) nearly a factor of\n10 higher star formation activity concentrated in scales around 2 kpc in\ngalaxies with stellar masses $\\sim10^8$ M$_\\odot$ during the first 350 Myr of\nthe Universe, $z\\sim12$, with models matching better the luminosity density\nobservational estimations $\\sim$150 Myr later, by $z\\sim9$.", "positive": "Spatially Resolved Properties of Galaxies with a Kinematically Distinct\n Core: Aims. Interacting galaxies show unique irregularities in their kinematic\nstructure. By investigating the spatially resolved kinematics and stellar\npopulation properties of galaxies that show irregularities, we can paint a\ndetailed picture of the formation and evolutionary processes that took place\nduring its lifetimes. Methods. In this work, we focus on galaxies with a\nspecific kinematic irregularity, a kinematically distinct stellar core (KDC),\nin particular, counter-rotating galaxies where the core and main body of the\ngalaxy are rotating in opposite directions. We visually identify eleven MaNGA\ngalaxies with a KDC from their stellar kinematics, and investigate their\nspatially resolved stellar and gaseous kinematic properties, namely the\ntwo-dimensional stellar and gaseous velocity and velocity dispersion ({\\sigma})\nmaps. Additionally, we examine the stellar population properties, as well as\nspatially resolved recent star formation histories using the Dn4000 and\nH{\\delta} gradients. Results. The galaxies display multiple off-centred,\nsymmetrical peaks in the stellar {\\sigma} maps. The gaseous velocity and\n{\\sigma} maps display regular properties. The stellar population properties and\ntheir respective gradients show differing properties depending on the results\nof the spatially resolved emission line diagnostics of the galaxies, with some\ngalaxies showing inside-out quenching but others not. The star formation\nhistories also largely differ based on the spatially resolved emission line\ndiagnostics, but most galaxies show indications of recent star formation either\nin their outskirts or core. Conclusions. We find a distinct difference in\nkinematic and stellar population properties in galaxies with a counter-rotating\nstellar core, depending on its classification using spatially resolved emission\nline diagnostics." }, { "anchor": "Discovery of a z=0.65 Post-Starburst BAL Quasar in the DES Supernova\n Fields: We present the discovery of a z=0.65 low-ionization broad absorption line\n(LoBAL) quasar in a post-starburst galaxy in data from the Dark Energy Survey\n(DES) and spectroscopy from the Australian Dark Energy Survey (OzDES). LoBAL\nquasars are a minority of all BALs, and rarer still is that this object also\nexhibits broad FeII (an FeLoBAL) and Balmer absorption. This is the first BAL\nquasar that has signatures of recently truncated star formation, which we\nestimate ended about 40 Myr ago. The characteristic signatures of an FeLoBAL\nrequire high column densities, which could be explained by the emergence of a\nyoung quasar from an early, dust-enshrouded phase, or by clouds compressed by a\nblast wave. The age of the starburst component is comparable to estimates of\nthe lifetime of quasars, so if we assume the quasar activity is related to the\ntruncation of the star formation, this object is better explained by the blast\nwave scenario.", "positive": "Chronology of our Galaxy from Gaia Colour-Magnitude Diagram-fitting\n (ChronoGal). I. The formation and evolution of the thin disk from the Gaia\n Catalogue of Nearby Stars: The current major challenge to reconstruct the chronology of the Milky Way\n(MW) is the difficulty to derive precise stellar ages. CMD-fitting offers an\nalternative to individual age determinations to derive the star formation\nhistory (SFH). We present CMDft.Gaia and use it to analyse the CMD of the Gaia\nCatalogue of Nearby Stars (GCNS), which contains a census of the stars within\n100 pc of the Sun. The result is an unprecedented detailed view of the\nevolution of the MW disk. The bulk of star formation started 11-10.5 Gyr ago at\n[Fe/H]~solar and continued with a slightly decreasing metallicity trend until 6\nGyr ago. Between 6-4 Gyr ago, a break in the age-metallicity distribution is\nobserved, with 3 stellar populations with distinct metallicities (sub-solar,\nsolar, and super-solar), possibly indicating some dramatic event in the Galaxy.\nStar formation resumed 4 Gyr ago with a bursty behaviour, metallicity near\nsolar and higher average SFR. The derived metallicity distribution closely\nmatches precise spectroscopic data, which also show stellar populations\ndeviating from solar metallicity. Interestingly, our results reveal the\npresence of intermediate-age populations with both a metallicity typical of the\nthick disk and supersolar metallicity. Our many tests indicate that, with high\nprecision Gaia photometric and distance data, CMDft.Gaia can achieve a\nprecision ~10% and an accuracy better than 6% in the dating of even old stellar\npopulations. The comparison with independent spectroscopic data shows that\nmetallicity distributions are determined with high precision, without imposing\na-priory metallicity information. This opens the door to obtaining detailed and\nrobust information on the evolution of the stellar populations of the MW over\ncosmic time. As an example we provide an unprecedented detailed view of the age\nand metallicity distributions of the stars within 100 pc of the Sun." }, { "anchor": "Quantitative Spectroscopy of Blue Supergiants in Metal-Poor Dwarf Galaxy\n NGC 3109: We present a quantitative analysis of the low-resolution (4.5 A) spectra of\n12 late-B and early-A blue supergiants (BSGs) in the metal-poor dwarf galaxy\nNGC 3109. A modified method of analysis is presented which does not require use\nof the Balmer jump as an independent temperature indicator, as used in previous\nstudies. We determine stellar effective temperatures, gravities, metallicities,\nreddening, and luminosities, and combine our sample with the early-B type BSGs\nanalyzed by Evans et al. (2007) to derive the distance to NGC 3109 using the\nFlux-weighted Gravity-Luminosity Relation (FGLR). Using primarily Fe-group\nelements, we find an average metallicity of [Z] = -0.67 +/- 0.13, and no\nevidence of a metallicity gradient in the galaxy. Our metallicities are higher\nthan those found by Evans et al. (2007) based on the oxygen abundances of\nearly-B supergiants ([Z] = -0.93 +/- 0.07), suggesting a low alpha/Fe ratio for\nthe galaxy. We adjust the position of NGC 3109 on the BSG-determined galaxy\nmass-metallicity relation accordingly and compare it to metallicity studies of\nHII regions in star-forming galaxies. We derive an FGLR distance modulus of\n25.55 +/- 0.09 (1.27 Mpc) that compares well with Cepheid and tip of the red\ngiant branch (TRGB) distances. The FGLR itself is consistent with those found\nin other galaxies, demonstrating the reliability of this method as a measure of\nextragalactic distances.", "positive": "The Excess Density of Field Galaxies near z=0.56 around the Gamma-Ray\n Burst GRB021004 Position: We test for reliability any signatures of field galaxies clustering in the\nGRB 021004 line of sight. The first signature is the GRB 021004 field\nphotometric redshifts distribution based on the 6-m telescope of the Special\nAstrophysical Observatory of the Russian Academy of Sciences observations with\na peak near z = 0.56 estimated from multicolor photometry in the GRB direction.\nThe second signature is the Mg II 2796, 2803AA absorption doublet at z = 0.56\nin VLT/UVES spectra obtained for the GRB 021004 afterglow. The third signature\nis the galaxy clustering in a larger (of about 3 sq.deg.) area around GRB\n021004 with an effective peak near z = 0.56 for both the spectral and\nphotometric redshifts from a few catalogs of clusters based on the Sloan\nDigital Sky Survey (SDSS) and Baryon Oscillation Spectroscopic Survey (BOSS) as\na part of SDSS-III. From catalog data the size of the whole inhomogeneity in\ndistribution of the galaxy cluster with the peak near z = 0.56 was also\nestimated as about 6--8 deg. or 140--190 Mpc. A possibility of inhomogeneity (a\ngalaxy cluster) near the GRB 021004 direction can be also confirmed by an\ninhomogeneity in cosmic microwave background related with the Sunyaev-Zeldovich\neffect." }, { "anchor": "The Origin of UV-optical Variability in AGN and Test of Disc Models:\n XMM-Newton and ground based observations of NGC4395: The origin of short timescale (weeks/months) variability of AGN, whether due\nto intrinsic disc variations or reprocessing of X-ray emission by a surrounding\naccretion disc, has been a puzzle for many years. However recently a number of\nobservational programmes, particularly of NGC5548 with Swift, have shown that\nthe UV/optical variations lag behind the X-ray variations in a manner strongly\nsupportive of X-ray reprocessing. Somewhat surprisingly the implied size of the\naccretion disc is ~3x greater than expected from a standard, smooth,\nShakura-Sunyaev thin disc model. Although the difference may be explained by a\nclumpy accretion disc, it is not clear whether the difference will occur in all\nAGN or whether it may change as, eg, a function of black hole mass, accretion\nrate or disc temperature. Measurements of interband lags for most AGN require\nlong timescale monitoring, which is hard to arrange. However for low mass (<1\nmillion solar mass) AGN, the combination of XMM-Newton EPIC (X-rays) with the\noptical monitor in fast readout mode allows an X-ray/UV-optical lag to be\nmeasured within a single long observation. Here we summarise previous related\nobservations and report on XMM-Newton observations of NGC4395 (mass ~100x lower\nand accretion rate ~20x lower than for NGC5548). We find that the UVW1 lags the\nX-rays by ~470s. Simultaneous observations at 6 different ground based\nobservatories also allowed the g-band lag (~800s) to be measured. These\nobservations are in agreement with X-ray reprocessing but initial analysis\nsuggests that, for NGC4395, they do not differ markedly from the predictions of\nthe standard thin disc model.", "positive": "Dusting off the diffuse interstellar bands: DIBs and dust in\n extragalactic SDSS spectra: Using over a million and a half extragalactic spectra we study the properties\nof the mysterious Diffuse Interstellar Bands (DIBs) in the Milky Way. These\ndata provide us with an unprecedented sampling of the skies at high\nGalactic-latitude and low dust-column-density. We present our method, study the\ncorrelation of the equivalent width of 8 DIBs with dust extinction and with a\nfew atomic species, and the distribution of four DIBs - 5780.6A, 5797.1A,\n6204.3A, and 6613.6A - over nearly 15000 squared degrees. As previously found,\nDIBs strengths correlate with extinction and therefore inevitably with each\nother. However, we show that DIBs can exist even in dust free areas.\nFurthermore, we find that the DIBs correlation with dust varies significantly\nover the sky. DIB under- or over-densities, relative to the expectation from\ndust, are often spread over hundreds of square degrees. These patches are\ndifferent for the four DIBs, showing that they are unlikely to originate from\nthe same carrier, as previously suggested." }, { "anchor": "Spectroscopic confirmation and velocity dispersions for twenty Planck\n galaxy clusters at 0.16300 M_{\\odot}$) Stars in Early Galaxies: We present element abundance ratios and ionizing radiation of local young\nlow-mass (~$10^{6}$ M_sun) extremely metal poor galaxies (EMPGs) with a 2%\nsolar oxygen abundance (O/H)_sun and a high specific star-formation rate\n(sSFR~300 Gyr$^{-1}$), and other (extremely) metal poor galaxies, which are\ncompiled from Extremely Metal-Poor Representatives Explored by the Subaru\nSurvey (EMPRESS) and the literature. Weak emission lines such as [FeIII]4658\nand HeII4686 are detected in very deep optical spectra of the EMPGs taken with\n8m-class telescopes including Keck and Subaru (Kojima et al. 2019, Izotov et\nal. 2018), enabling us to derive element abundance ratios with photoionization\nmodels. We find that neon- and argon-to-oxygen ratios are comparable to those\nof known local dwarf galaxies, and that the nitrogen-to-oxygen abundance ratios\n(N/O) are lower than 20% (N/O)_sun consistent with the low oxygen abundance.\nHowever, the iron-to-oxygen abundance ratios (Fe/O) of the EMPGs are generally\nhigh; the EMPGs with the 2%-solar oxygen abundance show high Fe/O ratios of\n~90-140% (Fe/O)_sun, which are unlikely explained by suggested scenarios of\nType Ia supernova iron productions, iron's dust depletion, and metal-poor gas\ninflow onto previously metal-riched galaxies with solar abundances. Moreover,\nthese EMPGs have very high HeII4686/H$\\beta$ ratios of ~1/40, which are not\nreproduced by existing models of high-mass X-ray binaries whose progenitor\nstellar masses are less than 120 M_sun. Comparing stellar-nucleosynthesis and\nphotoionization models with a comprehensive sample of EMPGs identified by this\nand previous EMPG studies, we propose that both the high Fe/O ratios and the\nhigh HeII4686/H$\\beta$ ratios are explained by the past existence of super\nmassive ($>$300 M_sun) stars, which may evolve into intermediate-mass black\nholes ($\\gtrsim$100 M_sun)." }, { "anchor": "Spatially resolved MaNGA observations of the host galaxy of\n superluminous supernova 2017egm: Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies,\nindicating that their progenitors have a low metallicity. However, the most\nnearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which\nhas a relatively high stellar mass and correspondingly high metallicity. In\nthis paper, we present detailed analysis of the nearby environment of SN\n2017egm using MaNGA IFU data, which provides spectral data on kiloparsec\nscales. From the velocity map we find no evidence that SN 2017egm occurred\nwithin some intervening satellite galaxy, and at the SN position most\nmetallicity diagnostics yield a solar and above solar metallicity (12 + log\n(O/H) = 8.8-9.1). Additionally we measure a small H-alpha equivalent width (EW)\nat the SN position of just 34 Angs, which is one of the lowest EWs measured at\nany SLSN or Gamma-Ray Burst position, and indicative of the progenitor star\nbeing comparatively old. We also compare the observed properties of NGC 3191\nwith other SLSN host galaxies. The solar-metallicity environment at the\nposition of SN 2017egm presents a challenge to our theoretical understanding,\nand our spatially resolved spectral analysis provides further constraints on\nthe progenitors of SLSNe.", "positive": "Dissecting stellar chemical abundance space with t-SNE: In the era of industrial Galactic astronomy and multi-object spectroscopic\nstellar surveys, the sample sizes and the number of available stellar chemical\nabundances have reached dimensions in which it has become difficult to process\nall the available information in an effective manner. In this paper we\ndemonstrate the use of a dimensionality-reduction technique (t-distributed\nstochastic neighbour embedding; t-SNE) for analysing the stellar\nabundance-space distribution. While the non-parametric non-linear behaviour of\nthis technique makes it difficult to estimate the significance of found\nabundance-space substructure, we show that our results depend little on\nparameter choices and are robust to abundance errors. By reanalysing the\nhigh-resolution high-signal-to-noise solar-neighbourhood HARPS-GTO sample with\nt-SNE, we find clearer chemical separations of the high- and low-[$\\alpha$/Fe]\ndisc sequences, hints for multiple populations in the high-[$\\alpha$/Fe]\npopulation, and indications that the chemical evolution of the\nhigh-[$\\alpha$/Fe] metal-rich stars is connected with the super-metal-rich\nstars. We also identify a number of chemically peculiar stars, among them a\nhigh-confidence s-process-enhanced abundance-ratio pair (HD91345/HD126681) with\nvery similar ages and $v_X$ and $v_Y$ velocities, which we suggest to have a\ncommon birth origin, possibly a dwarf galaxy. Our results demonstrate the\npotential of abundance-space t-SNE and similar methods for chemical-tagging\nstudies with large spectroscopic surveys." }, { "anchor": "Feedback from central black holes in elliptical galaxies. I: models with\n either radiative or mechanical feedback but not both: The importance of the radiative feedback from SMBHs at the centers of\nelliptical galaxies is not in doubt, given the well established relations among\nelectromagnetic output, black hole mass and galaxy optical luminosity. In\naddition, feedback due to mechanical and thermal deposition of energy from jets\nand winds emitted by the accretion disk around the central SMBH is also\nexpected to occur. In this paper we improve and extend the accretion and\nfeedback physics explored in our previous papers to include also a physically\nmotivated mechanical feedback. We study the evolution of an isolated elliptical\ngalaxy with the aid of a high-resolution 1-D hydrodynamical code, where the\ncooling and heating functions include photoionization and Compton effects, and\nrestricting to models which include only radiative or only mechanical feedback.\nWe confirm that for Eddington ratios above 0.01 both the accretion and\nradiative output are forced by feedback effects to be in burst mode, so that\nstrong intermittencies are expected at early times, while at low redshift the\nexplored models are characterized by smooth, very sub-Eddington mass accretion\nrates punctuated by rare outbursts. However, the explored models always fail\nsome observational tests. If we assume the high mechanical efficiency of\n10^{-2.3}, we find that most of the gas is ejected from the galaxy, the\nresulting X-ray luminosity is far less than is typically observed and little\nSMBH growth occurs. But models with low enough mechanical efficiency to\naccomodate satisfactory SMBH growth tend to allow too strong cooling flows and\nleave galaxies at z=0 with E+A spectra more frequently than is observed. We\nconclude that both types of feedback are required. Models with combined\nfeedback are explored in a forthcoming paper [abridged]", "positive": "Dynamical stellar mass-to-light ratio gradients: Evidence for very\n centrally concentrated IMF variations in ETGs?: Evidence from different probes of the stellar initial mass function (IMF) of\nmassive early-type galaxies (ETGs) has repeatedly converged on IMFs more\nbottom-heavy than in the Milky Way (MW). This consensus has come under scrutiny\ndue to often contradictory results from different methods on the level of\nindividual galaxies. In particular, a number of strong lensing probes are\nostensibly incompatible with a non-MW IMF. Radial gradients of the IMF --\nrelated to gradients of the stellar mass-to-light ratio $\\Upsilon$ -- can\npotentially resolve this issue. We construct Schwarzschild models allowing for\n$\\Upsilon$-gradients in seven massive ETGs with MUSE and SINFONI observations.\nWe find dynamical evidence that $\\Upsilon$ increases towards the center for all\nETGs. The gradients are confined to sub-kpc scales. Our results suggest that\nconstant-$\\Upsilon$ models may overestimate the stellar mass of galaxies by up\nto a factor 1.5. For all except one galaxy, we find a radius where the total\ndynamical mass has a minimum. This minimum places the strongest constraints on\nthe IMF outside the center and appears at roughly 1 kpc. We consider the IMF at\nthis radius characteristic for the main body of each ETG. In terms of the IMF\nmass-normalization $\\alpha$ relative to a Kroupa IMF, we find on average a\nMW-like IMF $<\\alpha_{main}> = 1.03 \\pm 0.19$. In the centers, we find\nconcentrated regions with increased mass normalizations that are less extreme\nthan previous studies suggested, but still point to a Salpeter-like IMF,\n$<\\alpha_{cen}> = 1.54 \\pm 0.15$" }, { "anchor": "Critical take on \"Mass models of disk galaxies from the DiskMass Survey\n in MOND\": Angus et al. (2015) have recently faulted MOND as follows: Studying thirty\ndisc galaxies from the DiskMass survey, they derive the profiles of velocity\ndispersion perpendicular to the discs as predicted by MOND, $\\sigma_M(r)$, and\ncompare them with $\\sigma(r)$, measured as part of the DiskMass project. This\nis a new test of MOND, different from rotation-curve analysis. A nontrivial\naccomplishment of MOND -- not discussed by Angus et al. -- is that the shapes\nof $\\sigma_M$ and $\\sigma$ agree very well, i.e,\n$\\eta(r)\\equiv\\sigma_M(r)/\\sigma(r)$ is well consistent with being\n$r$-independent (while $\\sigma$ and $\\sigma_M$ are strongly $r$ dependent). The\nfault found with MOND was that $\\eta$ is systematically above 1 (with an\naverage of about 1.3). I have suggested to Angus et al. that the fault may lie\nwith the DiskMass dispersions, which may well be too low for the purpose at\nhand: Being based on population-integrated line profiles, they may be\noverweighed by younger populations, known to have much smaller dispersions, and\nscale heights, than the older populations, which weigh more heavily on the\nlight distributions. I discuss independent evidence that supports this view,\nand show, besides, that if the DiskMas dispersions are underestimates by only\n25 %, on average, the MOND predictions are in full agreement with the data, in\nshape and magnitude. Now, Aniyan et al. (2015) have questioned the DiskMass\n$\\sigma$ on the same basis. They show for the solar column in the Milky Way\nthat: \" Combining the (single) measured velocity dispersion of the total young\n+ old disc population... with the scale height estimated for the older\npopulation would underestimate the disc surface density by a factor of $\\sim\n2.$\" If this mismatch found for the Milky Way is typical, correcting for it\nwould bring the measured DiskMass $\\sigma(r)$ to a remarkable agreement with\nthe predicted MOND $\\sigma_M(r)$.", "positive": "Dust variations in the diffuse interstellar medium: constraints on Milky\n Way dust from Planck-HFI observations: The Planck-HFI all-sky survey from 353 to 857GHz combined with the 100\nmicrons IRAS show that the dust properties vary in the diffuse ISM at high\nGalactic latitude (1e19+0.7\nstars (with [Fe/H]<-2.8) have been enriched by Pop III supernovae at a $>20\\%$\nlevel, and all [C/Fe]>+2 stars at a $>95\\%$ level. All very metal-poor stars\nwith $\\rm [C/Fe]<0$ are predicted to be predominantly enriched by Pop III\nhypernovae and/or pair instabillity supernovae. To better constrain the\nprimordial EDF, it is absolutely crucial to have a complete and accurate\ndetermination of the metallicity distribution function, and the properties of\nC-enhanced metal-poor stars (frequency and [C/Fe]) in the Galactic halo.", "positive": "Uncloaking globular clusters in the inner Galaxy: Extensive photometric studies of the globular clusters located towards the\ncenter of the Milky Way have been historically neglected. The presence of\npatchy differential reddening in front of these clusters has proven to be a\nsignificant obstacle to their detailed study. We present here a well-defined\nand reasonably homogeneous photometric database for 25 of the brightest\nGalactic globular clusters located in the direction of the inner Galaxy. These\ndata were obtained in the B, V, and I bands using the Magellan 6.5m telescope\nand the Hubble Space Telescope. A new technique is extensively used in this\npaper to map the differential reddening in the individual cluster fields, and\nto produce cleaner, dereddened color-magnitude diagrams for all the clusters in\nthe database. Subsequent papers will detail the astrophysical analysis of the\ncluster populations, and the properties of the obscuring material along the\nclusters' lines of sight." }, { "anchor": "A search for ionized jets towards massive young stellar objects: Radio continuum observations using the Australia telescope compact array at\n5.5, 9.0, 17.0 and 22.8 GHz have detected free-free emission associated with 45\nof 49 massive young stellar objects and HII regions. Of these, 26 sources are\nclassified as ionized jets (12 of which are candidates), 2 as ambiguous jets or\ndisc winds, 1 as a disc-wind, 14 as HII regions and 2 were unable to be\ncategorised. Classification as ionized jets is based upon morphology, radio\nflux and spectral index, in conjunction with previous observational results at\nother wavelengths. Radio-luminosity and momentum are found to scale with\nbolometric luminosity in the same way as low-mass jets, indicating a common\nmechanism for jet production across all masses. In 13 of the jets, we see\nassociated non-thermal/optically-thin lobes resulting from shocks either\ninternal to the jet and/or at working surfaces. Ten jets display non-thermal\n(synchrotron emission) spectra in their lobes, with an average spectral index\nof -0.55 consistent with Fermi acceleration in shocks. This shows that magnetic\nfields are present, in agreement with models of jet formation incorporating\nmagnetic fields. Since the production of collimated radio jets is associated\nwith accretion processes, the results presented in this paper support the\npicture of disc-mediated accretion for the formation of massive stars with an\nupper-limit on the jet phase lasting approximately $6.5 \\times 10^4 yr$.\nTypical mass loss rates in the jet are found to be $1.4 \\times 10^{-5} M_\\odot\nyr^{-1}$ with associated momentum rates of the order $(1-2) \\times 10^{-2}\nM_\\odot km s^{-1} yr^{-1}$.", "positive": "Tracing interstellar magnetic field using velocity gradient technique:\n Application to Atomic Hydrogen data: The advancement of our understanding of MHD turbulence opens ways to develop\nnew techniques to probe magnetic fields. In MHD turbulence, the velocity\ngradients are expected to be perpendicular to magnetic fields and this fact was\nused by Gonsalvez-Casanova & Lazarian to introduce a new technique to trace\nmagnetic fields using velocity centroid gradients. The latter can be obtained\nfrom spectroscopic observations. We apply the technique to GALFA HI survey data\nand compare the directions of magnetic fields obtained with our technique with\nthe direction of magnetic fields obtained using PLANCK polarization. We find\nexcellent correspondence between the two ways of magnetic field tracing, which\nis obvious via visual comparison and through measuring of the statistics of\nmagnetic field fluctuations obtained with the polarization data and our\ntechnique. This suggests that the velocity centroid gradients can provide a\nreliable way of measuring of the foreground magnetic field fluctuations and\nthus provide a new way of separating foreground and CMB polarization signals." }, { "anchor": "The JCMT BISTRO Survey: The Distribution of Magnetic Field Strengths\n towards the OMC-1 Region: Measurement of magnetic field strengths in a molecular cloud is essential for\ndetermining the criticality of magnetic support against gravitational collapse.\nIn this paper, as part of the JCMT BISTRO survey, we suggest a new application\nof the Davis-Chandrasekhar-Fermi (DCF) method to estimate the distribution of\nmagnetic field strengths in the OMC-1 region. We use observations of dust\npolarization emission at 450 $\\mu$m and 850 $\\mu$m, and C$^{18}$O (3-2)\nspectral line data obtained with the JCMT. We estimate the volume density, the\nvelocity dispersion and the polarization angle dispersion in a box, 40$''$\n$\\times$ 40$''$ (5$\\times$5 pixels), which moves over the OMC-1 region. By\nsubstituting three quantities in each box to the DCF method, we get magnetic\nfield strengths over the OMC-1 region. We note that there are very large\nuncertainties in inferred field strengths, as discussed in detail in this\npaper. The field strengths vary from 0.8 to 26.4 mG and their mean value is\nabout 6 mG. Additionally, we obtain maps of the mass-to-flux ratio in units of\na critical value and the Alfv$\\acute{e}$n mach number. The central parts of the\nBN-KL and South (S) clumps in the OMC-1 region are magnetically supercritical,\nso the magnetic field cannot support the clumps against gravitational collapse.\nHowever, the outer parts of the region are magnetically subcritical. The mean\nAlfv$\\acute{e}$n mach number is about 0.4 over the region, which implies that\nthe magnetic pressure exceeds the turbulent pressure in the OMC 1 region.", "positive": "On the Origin of the Globular Cluster FSR 1758: Globular clusters in the Milky Way are thought to have either an {\\it in\nsitu} origin, or to have been deposited in the Galaxy by past accretion events,\nlike the spectacular Sagittarius dwarf galaxy merger. We aim to probe the\norigin of the recently discovered globular cluster FSR 1758, often associated\nwith some past merger event, and which happens to be projected toward the\nGalactic bulge, by a detailed study of its Galactic orbit, and to assign it to\nthe most suitable Galactic component. We employ three different analytical\ntime-independent potential models to calculate the orbit of the cluster by\nusing the Gauss Radau spacings integration method. In addition, a\ntime-dependent bar potential model is added to account for the influence of the\nGalactic bar. We run a large suite of simulations to account for the\nuncertainties in the initial conditions, in a Montecarlo fashion. We confirm\nprevious indications that the globular cluster FSR 1758 possesses a retrograde\norbits with high eccentricity. The comparative analysis of the orbital\nparameters of star clusters in the Milky Way, in tandem with recent metallicity\nestimates, allows us to conclude that FSR1758 is indeed a Galactic bulge\nintruder. The cluster can therefore be considered an old metal poor halo\nglobular cluster formed {\\it in situ} and which is passing right now in the\nbulge region. Its properties, however, can be roughly accounted for also\nassuming that the cluster is part of some stream of extra-Galactic origin. We\nconclude that assessing the origin, either Galactic or extra-galactic, of\nglobular clusters is surely a tantalising task. In any case, by using an {\\it\nOccam's razor} argument, we tend to prefer an {\\it in situ} origin for FSR\n1758." }, { "anchor": "Revisiting Stellar Orbits and the Sgr A$^*$ Quadrupole Moment: The \"no-hair\" theorem can, in principle, be tested at the center of the Milky\nWay by measuring the spin and the quadrupole moment of Sgr A$^*$ with the\norbital precession of S-stars, measured over their full periods. Contrary to\nthe original method, we show why it is possible to test the no-hair theorem\nusing observations from only a single star, by measuring precession angles over\na half-orbit. There are observational and theoretical reasons to expect S-stars\nto spin rapidly, and we have quantified the effect of stellar spin, via\nspin-curvature coupling (the leading-order manifestation of the\nMathisson-Papapetrou-Dixon equations), on future quadrupole measurements. We\nfind that they will typically suffer from errors of order a few percentage\npoints, but for some orbital parameters, the error can be much higher. We\nre-examine the more general problem of astrophysical noise sources that may\nimpede future quadrupole measurements, and find that a judicious choice of\nmeasurable precession angles can often eliminate individual noise sources. We\nhave derived optimal combinations of observables to eliminate the large noise\nsource of mass precession, the novel noise of spin-curvature coupling due to\nstellar spin, and the more complicated noise source arising from transient\nquadrupole moments in the stellar potential.", "positive": "Class I methanol masers in low-mass star formation regions: Four Class I maser sources were detected at 44, 84, and 95 GHz toward\nchemically rich outflows in the regions of low-mass star formation NGC 1333I4A,\nNGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a\nsimilar outflow, NGC 2023. Flux densities of the newly detected masers are no\nmore than 18 Jy, being much lower than those of strong masers in regions of\nhigh-mass star formation. The brightness temperatures of the strongest peaks in\nNGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of\nthe peak in NGC 1333I2A is only 176 K. However, rotational diagram analysis\nshowed that the latter source is also a maser. The main properties of the newly\ndetected masers are similar to those of Class I methanol masers in regions of\nmassive star formation. The former masers are likely to be an extension of the\nlatter maser population toward low luminosities of both the masers and the\ncorresponding YSOs." }, { "anchor": "Timing Argument take on the Milky Way and Andromeda past-encounter: The two-body problem of $M31$ and the Milky Way (MW) galaxies with a\nCosmological Constant background is studied, with emphasis on the possibility\nthat they experienced Past Encounter (PE). PE are possible only for non-zero\ntransverse velocity and their viability is subject to observations of the\nimprints of such near collisions. By implementing the Timing Argument (TA) for\ntwo isolated point bodies, it is shown that if $M{31}$ and the MW have had PE,\nthen the predicted mass of the Local Group (LG) should be twice larger. Since\nthe predicted mass is too large, the MW and $M31$ galaxies should have collided\nat $\\sim 8 Gys$. Therefore, the TA analysis show that PE is not possible for\nthe Local Group (LG) system.", "positive": "The Highest Resolution Chandra View of Photoionization and Jet-Cloud\n Interaction in the Nuclear Region of NGC 4151: We report high resolution imaging of the nucleus of the Seyfert 1 galaxy NGC\n4151 obtained with a 50 ks Chandra HRC observation. The HRC image resolves the\nemission on spatial scales of 0.5\", ~30 pc, showing an extended X-ray\nmorphology overall consistent with the narrow line region (NLR) seen in optical\nline emission. Removal of the bright point-like nuclear source and image\ndeconvolution techniques both reveal X-ray enhancements that closely match the\nsubstructures seen in the Hubble Space Telescope [OIII] image and prominent\nknots in the radio jet. We find that most of the NLR clouds in NGC 4151 have\n[OIII] to soft X-ray ratio ~10, despite the distance of the clouds from the\nnucleus. This ratio is consistent with the values observed in NLRs of some\nSeyfert 2 galaxies, which indicates a uniform ionization parameter even at\nlarge radii and a density decreasing as $r^{-2}$ as expected for a nuclear wind\nscenario. The [OIII]/X-ray ratios at the location of radio knots show an excess\nof X-ray emission, suggesting shock heating in addition to photoionization. We\nexamine various mechanisms for the X-ray emission and find that, in contrast to\njet-related X-ray emission in more powerful AGN, the observed jet parameters in\nNGC 4151 are inconsistent with synchrotron emission, synchrotron self-Compton,\ninverse Compton of CMB photons or galaxy optical light. Instead, our results\nfavor thermal emission from the interaction between radio outflow and NLR gas\nclouds as the origin for the X-ray emission associated with the jet. This\nsupports previous claims that frequent jet-ISM interaction may explain why jets\nin Seyfert galaxies appear small, slow, and thermally dominated, distinct from\nthose kpc scale jets in the radio galaxies." }, { "anchor": "The central cusps in dark matter halos: fact or fiction?: We investigate the reliability of standard N-body simulations by modelling of\nthe well-known Hernquist halo with the help of \\texttt{GADGET-2} code (which\nuses the tree algorithm to calculate the gravitational force) and \\texttt{ph4}\ncode (which uses the direct summation). Comparing the results, we find that the\ncore formation in the halo center (which is conventionally considered as the\nfirst sign of numerical effects, to be specific, of the collisional relaxation)\nhas nothing to do with the collisional relaxation, being defined by the\nproperties of the tree algorithm. This result casts doubts on the universally\nadopted criteria of the simulation reliability in the halo center. Though we\nuse a halo model, which is theoretically proved to be stationary and stable, a\nsort of numerical 'violent relaxation' occurs. Its properties suggest that this\neffect is highly likely responsible for the central cusp formation in\ncosmological modelling of the large-scale structure, and then the 'core-cusp\nproblem' is no more than a technical problem of N-body simulations.", "positive": "Raining in MKW 3s: a Chandra-MUSE analysis of X-ray cold filaments\n around 3CR 318.1: We present the analysis of X-ray and optical observations of gas filaments\nobserved in the radio source 3CR 318.1, associated with NGC 5920, the Brightest\nCluster Galaxy (BCG) of MKW 3s, a nearby cool core galaxy cluster. This work is\none of the first X-ray and optical analyses of filaments in cool core clusters\ncarried out using MUSE observations. We aim at identifying the main excitation\nprocesses responsible for the emission arising from these filaments. We\ncomplemented the optical VLT/MUSE observations, tracing the colder gas phase,\nwith X-ray $\\textit{Chandra}$ observations of the hotter highly ionized gas\nphase. Using the MUSE observations, we studied the emission line intensity\nratios along the filaments to constrain the physical processes driving the\nexcitation, and, using the $\\textit{Chandra}$ observations, we carried out a\nspectral analysis of the gas along these filaments. We found a spatial\nassociation between the X-ray and optical morphology of these filaments, which\nare colder and have lower metal abundance than the surrounding intra-cluster\nmedium (ICM), as already seen in other BCGs. Comparing with previous results\nfrom the literature for other BCGs, we propose that the excitation process that\nis most likely responsible for these filaments emission is a combination of\nstar formation and shocks, with a likely contribution from self-ionizing,\ncooling ICM. Additionally, we conclude that the filaments most likely\noriginated from AGN-driven outflows in the direction of the radio jet." }, { "anchor": "Spatially resolved X-ray spectroscopy and modeling of the nonthermal\n emission of the PWN in G0.9+0.1: We performed a spatially resolved spectral X-ray study of the pulsar wind\nnebula (PWN) in the supernova remnant G0.9+0.1. Furthermore we modeled its\nnonthermal emission in the X-ray and very high energy (VHE, E > 100 GeV)\ngamma-ray regime. Using Chandra ACIS-S3 data, we investigated the east-west\ndependence of the spectral properties of G0.9+0.1 by calculating hardness\nratios. We analyzed the EPIC-MOS and EPIC-pn data of two on-axis observations\nof the XMM-Newton telescope and extracted spectra of four annulus-shaped\nregions, centered on the region of brightest emission of the source. A radially\nsymmetric leptonic model was applied in order to reproduce the observed X-ray\nemission of the inner part of the PWN. Using the optimized model parameter\nvalues obtained from the X-ray analysis, we then compared the modeled inverse\nCompton (IC) radiation with the published H.E.S.S. gamma-ray data. The spectral\nindex within the four annuli increases with growing distance to the pulsar,\nwhereas the surface brightness drops. With the adopted model we are able to\nreproduce the characteristics of the X-ray spectra. The model results for the\nVHE gamma radiation, however, strongly deviate from the H.E.S.S. data.", "positive": "Metallicity and kinematical clues to the formation of the Local Group: The kinematics and elemental abundances of resolved stars in the nearby\nUniverse can be used to infer conditions at high redshift, trace how galaxies\nevolve and constrain the nature of dark matter. This approach is complementary\nto direct study of systems at high redshift, but I will show that analysis of\nindividual stars allows one to break degeneracies, such as between star\nformation rate and stellar Initial Mass Function, that complicate the analysis\nof unresolved, distant galaxies." }, { "anchor": "Star density profiles of six old star clusters in the Large Magellanic\n Cloud: We used resolved star counts from Hubble Space Telescope images to determine\nthe center of gravity and the projected density profiles of 6 old globular\nclusters in the Large Magellanic Cloud (LMC), namely NGC 1466, NGC 1841, NGC\n1898, NGC 2210, NGC 2257 and Hodge 11. For each system, the LMC field\ncontribution was properly taken into account by making use, when needed, of\nparallel HST observations. The derived values of the center of gravity may\ndiffer by several arcseconds (corresponding to more than 1 pc at the distance\nof the LMC) from previous determinations. The cluster density profiles are all\nwell fit by King models, with structural parameters that may differ from the\nliterature ones by even factors of two. Similarly to what observed for Galactic\nglobular clusters, the ratio between the effective and the core radii has been\nfound to anti-correlate with the cluster dynamical age.", "positive": "Mass distributions of star clusters for different star formation\n histories in a galaxy cluster environment: Clusters of galaxies usually contain rich populations of globular clusters\n(GCs). We investigate how different star formation histories (SFHs) shape the\nfinal mass distribution of star clusters. We assume that every star cluster\npopulation forms during a formation epoch of length dt at a constant\nstar-formation rate (SFR). The mass distribution of such a population is\ndescribed by the embedded cluster mass function (ECMF), which is a pure power\nlaw extending to an upper limit M_max. Since the SFR determines M_max, the ECMF\nimplicitly depends on the SFR. Starting with different SFHs, each SFH is\ndivided into formation epochs of length dt at different SFRs. The requested\nmass function arises from the superposition of the star clusters of all\nformation epochs. An improved optimal sampling technique is introduced that\nallows generating number and mass distributions, both of which accurately agree\nwith the ECMF. Moreover, for each SFH the distribution function of all involved\nSFRs, F(SFR), is computed. For monotonically decreasing SFHs, F(SFR) always\nfollows a power law. With F(SFR), we develope the theory of the integrated\ngalactic embedded cluster mass function (IGECMF). It describes the distribution\nfunction of birth stellar masses of star clusters that accumulated over a\nformation episode much longer than dt. The IGECMF indeed reproduces the mass\ndistribution of star clusters created according to the superposition principle.\nInterestingly, all considered SFHs lead to a turn-down with increasing star\ncluster mass in their respective IGECMFs. In the past, a turn-down at the\nhigh-mass end has been observed for GC systems in different galaxy clusters and\nin the cluster initial mass function. This behavior can be explained naturally\nif the observed star cluster ensembles are superpositions of several individual\nstar cluster populations that formed at different times at different SFRs." }, { "anchor": "[Mg/Fe] ratios in the solar neighbourhood: stellar yields and chemical\n evolution scenarios: Context. The [Mg/Fe] abundance ratios are a fundamental fossil signature to\ntrace the chemical evolution of the disc. Despite of the huge observational and\ntheoretical effort, discrepancies between models and data are still present and\nseveral explanations have been put forward to explain the [$\\alpha$/Fe]\nbimodality. Aims. In this work, we take advantage of a new AMBRE:HARPS dataset,\nwhich provides new and more precise [Mg/Fe] estimations, as well as reliable\nstellar ages for a subsample of stars, to study the evolution of the solar\nneighbourhood. Methods. The above data are compared with detailed chemical\nevolution models for the Milky Way, exploring the most used prescriptions for\nstellar yields and different formation scenarios for the Galactic disc, i.e.\nthe delayed two-infall and the parallel model, also including prescriptions for\nstellar radial migration. Results. We see that most of the stellar yields\nstruggle to reproduce the observed trend of the data and that semi-empirical\nyields are still the best to describe the [Mg/Fe] evolution in the thick and\nthin discs. In particular, most of the yields still predict a steeper decrease\nof the [Mg/Fe] ratio at high metallicity than what is shown by the data. The\nbulk of the data are well reproduced by the parallel and two-infall scenarios,\nbut both scenarios have problems in explaining the most metal-rich and\nmetal-poor tails of the low-$\\alpha$ data. These tails can be explained in\nlight of radial migration from inner and outer disc regions, respectively.\nConclusions. Despite of the evidence of stellar migration, it is difficult to\nestimate the actual contribution of stars from other parts of the disc to the\nsolar vicinity. However, the comparison between data and models suggests that\npeculiar histories of star formation, such as that of the two-infall model, are\nstill needed to reproduce the observed distribution of stars.", "positive": "3-D Radiative Transfer Calculations of Radiation Feedback from Massive\n Black Holes: Outflow of Mass from the Dusty \"Torus\": Observational and theoretical arguments suggest that the momentum carried in\nmass outflows from AGN can reach several times L / c, corresponding to outflow\nrates of hundreds of solar masses per year. Radiation pressure on lines alone\nmay not be sufficient to provide this momentum deposition, and the transfer of\nreprocessed IR radiation in dusty nuclear gas has been postulated to provide\nthe extra enhancement. The efficacy of this mechanism, however, will be\nsensitive to multi-dimensional effects such as the tendency for the reprocessed\nradiation to preferentially escape along sight-lines of lower column density.\nWe use Monte Carlo radiative transfer calculations to determine the radiation\nforce on dusty gas residing within approximately 10 parsecs from an accreting\nsuper-massive black hole. We calculate the net rate of momentum deposition in\nthe surrounding gas and estimate the mass-loss rate in the resulting outflow as\na function of solid angle for different black hole luminosities,\nsightline-averaged column densities, clumping parameters, and opening angles of\nthe dusty gas. We find that these dust-driven winds carry momentum fluxes of\n1-5 times L / c and correspond to mass-loss rates of 10-100 solar masses per\nyear for a 10^8 solar mass black hole radiating at or near its Eddington limit.\nThese results help to explain the origin of high velocity molecular and atomic\noutflows in local ULIRGs, and can inform numerical simulations of galaxy\nevolution including AGN feedback." }, { "anchor": "Deep Learning Assessment of galaxy morphology in S-PLUS DataRelease 1: The morphological diversity of galaxies is a relevant probe of galaxy\nevolution and cosmological structure formation, but the classification of\ngalaxies in large sky surveys is becoming a significant challenge. We use data\nfrom the Stripe-82 area observed by the Southern Photometric Local Universe\nSurvey (S-PLUS) in twelve optical bands, and present a catalogue of the\nmorphologies of galaxies brighter than $r=17$ mag determined both using a novel\nmulti-band morphometric fitting technique and Convolutional Neural Networks\n(CNNs) for computer vision. Using the CNNs we find that, compared to our\nbaseline results with 3 bands, the performance increases when using 5 broad and\n3 narrow bands, but is poorer when using the full $12$ band S-PLUS image set.\nHowever, the best result is still achieved with just 3 optical bands when using\npre-trained network weights from an ImageNet data set. These results\ndemonstrate the importance of using prior knowledge about neural network\nweights based on training in unrelated, extensive data sets, when available.\nOur catalogue contains 3274 galaxies in Stripe-82 that are not present in\nGalaxy Zoo 1 (GZ1), and we also provide our classifications for 4686 galaxies\nthat were considered ambiguous in GZ1. Finally, we present a prospect of a\nnovel way to take advantage of $12$ band information for morphological\nclassification using morphometric features, and we release a model that has\nbeen pre-trained on several bands that could be adapted for classifications\nusing data from other surveys. The morphological catalogues are publicly\navailable.", "positive": "HOLISMOKES -- II. Identifying galaxy-scale strong gravitational lenses\n in Pan-STARRS using convolutional neural networks: We present a systematic search for wide-separation (Einstein radius >1.5\"),\ngalaxy-scale strong lenses in the 30 000 sq.deg of the Pan-STARRS 3pi survey on\nthe Northern sky. With long time delays of a few days to weeks, such systems\nare particularly well suited for catching strongly lensed supernovae with\nspatially-resolved multiple images and open new perspectives on early-phase\nsupernova spectroscopy and cosmography. We produce a set of realistic\nsimulations by painting lensed COSMOS sources on Pan-STARRS image cutouts of\nlens luminous red galaxies with known redshift and velocity dispersion from\nSDSS. First of all, we compute the photometry of mock lenses in gri bands and\napply a simple catalog-level neural network to identify a sample of 1050207\ngalaxies with similar colors and magnitudes as the mocks. Secondly, we train a\nconvolutional neural network (CNN) on Pan-STARRS gri image cutouts to classify\nthis sample and obtain sets of 105760 and 12382 lens candidates with scores\npCNN>0.5 and >0.9, respectively. Extensive tests show that CNN performances\nrely heavily on the design of lens simulations and choice of negative examples\nfor training, but little on the network architecture. Finally, we visually\ninspect all galaxies with pCNN>0.9 to assemble a final set of 330 high-quality\nnewly-discovered lens candidates while recovering 23 published systems. For a\nsubset, SDSS spectroscopy on the lens central regions proves our method\ncorrectly identifies lens LRGs at z~0.1-0.7. Five spectra also show robust\nsignatures of high-redshift background sources and Pan-STARRS imaging confirms\none of them as a quadruply-imaged red source at z_s = 1.185 strongly lensed by\na foreground LRG at z_d = 0.3155. In the future, we expect that the efficient\nand automated two-step classification method presented in this paper will be\napplicable to the deeper gri stacks from the LSST with minor adjustments." }, { "anchor": "Exploring the Morphology and Origins of the 4C 38.41 Jet: We study the properties of the innermost jet of the flat spectrum radio\nquasar 1633+382 (4C~38.41) based on VLBI data from the radio monitoring\nobservations of the Boston University VLBI program at 43~GHz. Analysis of the\ncomponents suggests a semi-parabolic jet geometry with jet radius $R$ following\nthe relation $R\\propto r^{0.7}$ with distance $r$, with indications of a jet\ngeometry break towards a conical geometry. Brightness temperature falls with\ndistance following $T_B\\propto r^{-2.1}$. Combining this information, magnetic\nfield and electron densities are found to fall along the jet as $B\\propto\nr^{-1.5}$ and $n\\propto r^{-1.1}$ respectively, suggesting that the magnetic\nconfiguration in the jet may be dominated by the poloidal component. Our\nanalysis of the jet structure suggests that the innermost jet regions do not\nfollow a ballistic trajectory and, instead, match a sinusoidal morphology which\ncould be due to jet precession from a helical pattern or Kelvin-Helmholtz\ninstabilities.", "positive": "Wide-field CO isotopologue emission and the CO-to-H$_2$ factor across\n the nearby spiral galaxy M101: Carbon monoxide (CO) emission is the most widely used tracer of the bulk\nmolecular gas in the interstellar medium (ISM) in extragalactic studies. The\nCO-to-H$_2$ conversion factor, $\\alpha_{\\rm CO}$, links the observed CO\nemission to the total molecular gas mass. However, no single prescription\nperfectly describes the variation of $\\alpha_{\\rm CO}$ across all environments\nacross galaxies as a function of metallicity, molecular gas opacity, line\nexcitation, and other factors. Using resolved spectral line observations of CO\nand its isotopologues, we can constrain the molecular gas conditions and link\nthem to a variation in the conversion factor. We present new IRAM 30-m 1mm and\n3mm line observations of $^{12}$CO, $^{13}$CO, and C$^{18}$O} across the nearby\ngalaxy M101. Based on the CO isotopologue line ratios, we find that selective\nnucleosynthesis and opacity changes are the main drivers of the variation in\nthe line emission across the galaxy. Furthermore, we estimated $\\alpha_{\\rm\nCO(1-0)}$ using different approaches, including (i) the dust mass surface\ndensity derived from far-IR emission as an independent tracer of the total gas\nsurface density and (ii) LTE-based measurements using the optically thin\n$^{13}$CO(1-0) intensity. We find an average value of $\\alpha_{\\rm\nCO}=4.4{\\pm}0.9\\rm\\,M_\\odot\\,pc^{-2}(K\\,km\\,s^{-1})^{-1}$ across the galaxy,\nwith a decrease by a factor of 10 toward the 2 kpc central region. In contrast,\nwe find LTE-based values are lower by a factor of 2-3 across the disk relative\nto the dust-based result. Accounting for $\\alpha_{\\rm CO}$ variations, we found\nsignificantly reduced molecular gas depletion time by a factor 10 in the\ngalaxy's center. In conclusion, our result suggests implications for commonly\nderived scaling relations, such as an underestimation of the slope of the\nKennicutt Schmidt law, if $\\alpha_{\\rm CO}$ variations are not accounted for." }, { "anchor": "Anchors for the Cosmic Distance Scale: the Cepheids U Sgr, CF Cas and\n CEab Cas: New and existing X-ray, UBVJHKsW(1-4), and spectroscopic observations were\nanalyzed to constrain fundamental parameters for M25, NGC 7790, and dust along\ntheir sight-lines. The star clusters are of particular importance given they\nhost the classical Cepheids U Sgr, CF Cas, and the visual binary Cepheids CEa\nand CEb Cas. Precise results from the multiband analysis, in tandem with a\ncomprehensive determination of the Cepheids' period evolution (dP/dt) from ~140\nyears of observations, helped resolve concerns raised regarding the clusters\nand their key Cepheid constituents. Specifically, distances derived for members\nof M25 and NGC 7790 are 630+-25 pc and 3.40+-0.15 kpc, respectively.", "positive": "The VLA-COSMOS 3~GHz Large Project: AGN and host-galaxy properties out\n to z$\\lesssim$6: We explore the multiwavelength properties of AGN host galaxies for different\nclasses of radio-selected AGN out to z$\\lesssim$6 via a multiwavelength\nanalysis of about 7700 radio sources in the COSMOS field. The sources were\nselected with the Very Large Array (VLA) at 3 GHz (10 cm) within the VLA-COSMOS\n3 GHz Large Project, and cross-matched with multiwavelength ancillary data.\nThis is the largest sample of high-redshift (z$\\lesssim$6) radio sources with\nexquisite photometric coverage and redshift measurements available. We\nconstructed a sample of moderate-to-high radiative luminosity AGN (HLAGN) via\nspectral energy distribution (SED) decomposition combined with standard X-ray\nand mid-infrared diagnostics. Within the remainder of the sample we further\nidentified low-to-moderate radiative luminosity AGN (MLAGN) via excess in radio\nemission relative to the star formation rates in their host galaxies. We show\nthat AGN power in HLAGN occurs predominantly in radiative form, while MLAGN\ndisplay a substantial mechanical AGN luminosity component. We found significant\ndifferences in the host properties of the two AGN classes, as a function of\nredshift. At z$<$1.5, MLAGN appear to reside in significantly more massive and\nless star-forming galaxies compared to HLAGN. At z$>$1.5, we observed a\nreversal in the behaviour of the stellar mass distributions with the HLAGN\npopulating the higher stellar mass tail. We interpret this finding as a\npossible hint of the downsizing of galaxies hosting HLAGN, with the most\nmassive galaxies triggering AGN activity earlier than less massive galaxies,\nand then fading to MLAGN at lower redshifts. Our conclusion is that HLAGN and\nMLAGN samples trace two distinct galaxy and AGN populations in a wide range of\nredshifts, possibly resembling the radio AGN types often referred to as\nradiative- and jet-mode (or high- and low-excitation), respectively." }, { "anchor": "The LABOCA Survey of the Extended Chandra Deep Field South: Clustering\n of submillimetre galaxies: We present a measurement of the spatial clustering of submillimetre galaxies\n(SMGs) at z = 1-3. Using data from the 870 micron LESS survey, we employ a\nnovel technique to measure the cross-correlation between SMGs and galaxies,\naccounting for the full probability distributions for photometric redshifts of\nthe galaxies. From the observed projected two-point cross-correlation function\nwe derive the linear bias and characteristic dark matter (DM) halo masses for\nthe SMGs. We detect clustering in the cross-correlation between SMGs and\ngalaxies at the > 4 sigma level. For the SMG autocorrelation we obtain r_0 =\n7.7 (+1.8,-2.3) h^-1 Mpc, and derive a corresponding DM halo mass of log(M_halo\n[h^-1 M_sun]) = 12.8 (+0.3,-0.5). Based on the evolution of DM haloes derived\nfrom simulations, we show that that the z = 0 descendants of SMGs are typically\nmassive (~2-3 L*) elliptical galaxies residing in moderate- to high-mass groups\n(log(M_halo [h^-1 M_sun]) = 13.3 (+0.3,-0.5). From the observed clustering we\nestimate an SMG lifetime of ~100 Myr, consistent with lifetimes derived from\ngas consumption times and star-formation timescales, although with considerable\nuncertainties. The clustering of SMGs at z ~ 2 is consistent with measurements\nfor optically-selected quasi-stellar objects (QSOs), supporting evolutionary\nscenarios linking starbursts and QSOs. Given that SMGs reside in haloes of\ncharacteristic mass ~ 6 x 10^12 h^-1 M_sun, we demonstrate that the redshift\ndistribution of SMGs can be described remarkably well by the combination of two\neffects: the cosmological growth of structure and the evolution of the\nmolecular gas fraction in galaxies. We conclude that the powerful starbursts in\nSMGs likely represent a short-lived but universal phase in massive galaxy\nevolution, associated with the transition between cold gas-rich, star-forming\ngalaxies and passively evolving systems. [Abridged]", "positive": "A computational analysis of the reaction of atomic oxygen O(3P) with\n acrylonitrile: The work is focused on the characterization of a long-range interacting\ncomplex in the reaction between atomic oxygen, in its ground state O(3P) and\nacrylonitrile CH2CHCN, also known as vinyl cyanide or cyano ethylene, through\nelectronic structure calculations. Different ab initio methods have been used\nin order to understand which functional provides a better description of the\nlong-range interaction. The results of the work suggest that B2PLYPD3 gives the\nbest description of the long-range interaction, while CAM-B3LYP represents the\nbest compromise between chemical accuracy and computational cost." }, { "anchor": "Potential Black Hole Seeding of the Spiral Galaxy NGC 4424 via an\n Infalling Star Cluster: Galaxies can grow through their mutual gravitational attraction and\nsubsequent union. While orbiting a regular high-surface-brightness galaxy, the\nbody of a low-mass galaxy can be stripped away. However, the stellar heart of\nthe infalling galaxy, if represented by a tightly-bound nuclear star cluster,\nis more resilient. From archival Hubble Space Telescope images, we have\ndiscovered a red, tidally-stretched star cluster positioned ~5 arcseconds (~400\npc in projection) from, and pointing toward the center of, the post-merger\nspiral galaxy NGC 4424. The star cluster, which we refer to as `Nikhuli', has a\nnear-infrared luminosity of (6.88+/-1.85)x10^6 L_{solar,F160W} and likely\nrepresents the nucleus of a captured/wedded galaxy. Moreover, from our Chandra\nX-ray Observatory image, Nikhuli is seen to contain a high-energy X-ray point\nsource, with L_{0.5-8 keV} = 6.31^{+7.50}_{-3.77}x10^{38} erg/s (90%\nconfidence). We argue that this is more likely to be an active massive black\nhole than an X-ray binary. Lacking an outward-pointing comet-like appearance,\nthe stellar structure of Nikhuli favors infall rather than the ejection from a\ngravitational-wave recoil event. A minor merger with a low-mass early-type\ngalaxy may have sown a massive black hole, aided an X-shaped pseudobulge, and\nbe sewing a small bulge. The stellar mass and the velocity dispersion of NGC\n4424 predict a central black hole of (0.6-1.0)x10^5 M_solar, similar to the\nexpected intermediate-mass black hole in Nikhuli, and suggestive of a black\nhole supply mechanism for bulgeless late-type galaxies. We may potentially be\nwitnessing black hole seeding by capture and sinking, with a nuclear star\ncluster the delivery vehicle.", "positive": "The Impact of Type Ia Supernovae in Quiescent Galaxies: I. Formation of\n the Multiphase Interstellar medium: A cool phase of the interstellar medium has been observed in many giant\nelliptical galaxies, but its origin remains unclear. We propose that uneven\nheating from Type Ia supernovae (SNe Ia), together with radiative cooling, can\nlead to the formation of the cool phase. The basic idea is that since SNe Ia\nexplode randomly, gas parcels which are not directly heated by SN shocks will\ncool, forming multiphase gas. We run a series of idealized high-resolution\nnumerical simulations, and find that cool gas develops even when the overall\nSNe heating rate $H$ exceeds the cooling rate $C$ by a factor as large as 1.4.\nWe also find that the time for multiphase gas development depends on the gas\ntemperature. When the medium has a temperature $T = 3\\times 10^6$ K, the cool\nphase forms within one cooling time \\tc; however, the cool phase formation is\ndelayed to a few times \\tc\\ for higher temperatures. The main reason for the\ndelay is turbulent mixing. Cool gas formed this way would naturally have a\nmetallicity lower than that of the hot medium. For constant $H/C$, there is\nmore turbulent mixing for higher temperature gas. We note that this mechanism\nof producing cool gas cannot be captured in cosmological simulations, which\nusually fail to resolve individual SN remnants." }, { "anchor": "Ab initio Study of Ground-State CS Photodissociation Via Highly Excited\n Electronic States: Photodissociation by ultraviolet radiation is the key destruction pathway for\nCS in photon-dominated regions, such as diffuse clouds. However, the large\nuncertainties of photodissociation cross sections and rates of CS, resulting\nfrom a lack of both laboratory experiments and theoretical calculations, limit\nthe accuracy of calculated abundances of S-bearing molecules by modern\nastrochemical models. Here we show a detailed \\textit{ab initio} study of CS\nphotodissociation. Accurate potential energy curves of CS electronic states\nwere obtained by choosing an active space CAS(8,10) in MRCI+Q/aug-cc-pV(5+d)Z\ncalculation with additional diffuse functions, with a focus on the \\(B\\) and\n\\(C\\,^1\\Sigma^+\\) states. Cross sections for both direct photodissociation and\npredissociation from the vibronic ground state were calculated by applying the\ncoupled-channel method. We found that the \\(C-X\\) \\((0-0)\\) transition has\nextremely strong absorption due to a large transition dipole moment in the\nFranck-Condon region and the upper state is resonant with several triplet\nstates via spin-orbit couplings, resulting in predissociation to the main\natomic products C \\((^3P)\\) and S \\((^1D)\\). Our new calculations show the\nphotodissociation rate under the standard interstellar radiation field is\n\\(2.9\\ee{-9}\\)\\,s\\(^{-1}\\), with a 57\\% contribution from \\(C-X\\) \\((0-0)\\)\ntransition. This value is larger than that adopted by the Leiden\nphotodissociation and photoionization database by a factor of 3.0. Our accurate\n\\textit{ab initio} calculations will allow more secure determination of\nS-bearing molecules in astrochemical models.", "positive": "The Hierarchical Distribution of the Young Stellar Clusters in Six Local\n Star Forming Galaxies: We present a study of the hierarchical clustering of the young stellar\nclusters in six local (3--15 Mpc) star-forming galaxies using Hubble Space\nTelescope broad band WFC3/UVIS UV and optical images from the Treasury Program\nLEGUS (Legacy ExtraGalactic UV Survey). We have identified 3685 likely clusters\nand associations, each visually classified by their morphology, and we use the\nangular two-point correlation function to study the clustering of these stellar\nsystems. We find that the spatial distribution of the young clusters and\nassociations are clustered with respect to each other, forming large, unbound\nhierarchical star-forming complexes that are in general very young. The\nstrength of the clustering decreases with increasing age of the star clusters\nand stellar associations, becoming more homogeneously distributed after ~40--60\nMyr and on scales larger than a few hundred parsecs. In all galaxies, the\nassociations exhibit a global behavior that is distinct and more strongly\ncorrelated from compact clusters. Thus, populations of clusters are more\nevolved than associations in terms of their spatial distribution, traveling\nsignificantly from their birth site within a few tens of Myr whereas\nassociations show evidence of disruption occurring very quickly after their\nformation. The clustering of the stellar systems resembles that of a turbulent\ninterstellar medium that drives the star formation process, correlating the\ncomponents in unbound star-forming complexes in a hierarchical manner,\ndispersing shortly after formation, suggestive of a single, continuous mode of\nstar formation across all galaxies." }, { "anchor": "The Fundamental Manifold of spiral galaxies: ordered versus random\n motions and the morphology dependence of the Tully-Fisher relation: (Abridged) We investigate the morphology dependence of the Tully-Fisher\nrelation, and the expansion of the relation into a three-dimensional manifold\ndefined by luminosity, total circular velocity and a third dynamical parameter,\nto fully characterise spiral galaxies across all morphological types. We use a\nsemi-analytic hierarchical model of galaxy evolution to build the theoretical\nTF relation. With this tool, we analyse a unique dataset of galaxies for which\nwe cross-match luminosity with total circular velocity and central velocity\ndispersion. We provide a theoretical framework to calculate such measurable\nquantities from semi-analytic models. We establish the morphology dependence of\nthe TF relation in both model and data. We analyse the dynamical properties of\nthe model galaxies and determine that the parameter 'sigma/Vc', i.e. the ratio\nbetween random and total motions defined by velocity dispersion and circular\nvelocity, accurately characterises the varying slope of the TF relation for\ndifferent model galaxy types. We apply these dynamical cuts to the observed\ngalaxies and find that such selection produces a differential slope of the TF\nrelation. The TF slope in different ranges of 'sigma/Vc' is consistent with\nthat for the photometric classification in Sa, Sb, Sc. We conclude that\n'sigma/Vc' is a good parameter to classify galaxy type, and we argue that such\nclassification based on dynamics more closely mirrors the physical properties\nof the observed galaxies, compared to visual classification. We also argue that\ndynamical classification is useful for samples where eye inspection is not\nreliable or impractical. We conclude that 'sigma/Vc' is a suitable parameter to\ncharacterise the hierarchical assembly history that determines the\ndisk-to-bulge ratio, and to expand the TF relation into a three-dimensional\nmanifold, defined by luminosity, circular velocity and 'sigma/Vc'.", "positive": "The Mass-Concentration Relation and the Stellar-to-Halo Mass Ratio in\n the CFHT Stripe 82 Survey: We present a new measurement of the mass-concentration relation and the\nstellar-to-halo mass ratio over the halo mass range $5\\times 10^{12}$ to\n$2\\times 10^{14}M_{\\odot}$. To achieve this, we use weak lensing measurements\nfrom the CFHT Stripe 82 Survey (CS82), combined with the central galaxies from\nthe redMaPPer cluster catalogue and the LOWZ/CMASS galaxy sample of the Sloan\nDigital Sky Survey-III Baryon Oscillation Spectroscopic Survey Tenth Data\nRelease. The stacked lensing signals around these samples are modelled as a sum\nof contributions from the central galaxy, its dark matter halo, and the\nneighboring halos, as well as a term for possible centering errors. We measure\nthe mass-concentration relation: $c_{200c}(M)=A(\\frac{M_{200c}}{M_0})^{B}$ with\n$A=5.24\\pm1.24, B=-0.13\\pm0.10$ for $0.25%), hidden AGN, top-heavy initial mass function\n(possibly with Pop-III), and large scatter/variance. Having these successful\nand unsuccessful spectroscopy results, we suggest observational strategies for\nefficiently removing low redshift interlopers for future JWST programs." }, { "anchor": "Probing the physics of star formation (ProPStar): I. First resolved maps\n of the electron fraction and cosmic-ray ionization rate in NGC 1333: Electron fraction and cosmic-ray ionization rates (CRIR) in star-forming\nregions are important quantities in astrochemical modeling and are critical to\nthe degree of coupling between neutrals, ions, and electrons, which regulates\nthe dynamics of the magnetic field. However, these are difficult quantities to\nestimate. We aim to derive the electron fraction and CRIR maps of an active\nstar-forming region. We combined observations of the nearby NGC 1333\nstar-forming region carried out with the NOEMA interferometer and IRAM 30-m\nsingle dish to generate high spatial dynamic range maps of different molecular\ntransitions. We used the DCO$^+$ and H$^{13}$CO$^+$ ratio (in addition to\ncomplementary data) to estimate the electron fraction and produce cosmic-ray\nionization rate maps. We derived the first large-area electron fraction and\nCRIR resolved maps in a star-forming region, with typical values of $10^{-6.5}$\nand $10^{-16.5}$ s$^{-1}$, respectively. The maps present clear evidence of\nenhanced values around embedded young stellar objects (YSOs). This provides\nstrong evidence for locally accelerated cosmic rays. We also found a strong\nenhancement toward the northwest region in the map that might be related either\nto an interaction with a bubble or to locally generated cosmic rays by YSOs. We\nused the typical electron fraction and derived a MHD turbulence dissipation\nscale of 0.054 pc, which could be tested with future observations. We found a\nhigher cosmic-ray ionization rate compared to the canonical value for $N({\\rm\nH_2})=10^{21}-10^{23}$ cm$^{-2}$ of $10^{-17}$ s$^{-1}$ in the region, and it\nis likely generated by the accreting YSOs. The high value of the electron\nfraction suggests that new disks will form from gas in the ideal-MHD limit.\nThis indicates that local enhancements of $\\zeta({\\rm H_2})$, due to YSOs,\nshould be taken into account in the analysis of clustered star formation.", "positive": "A panchromatic spatially resolved study of the inner 500 pc of NGC 1052\n - I: Stellar population: We map optical and near-infrared (NIR) stellar population properties of the\ninner 320$\\times$535pc$^2$ of the elliptical galaxy NGC1052. The optical and\nNIR spectra were obtained using the Gemini Integral Field Units of the GMOS\ninstrument and NIFS, respectively. By performing stellar population synthesis\nin the optical alone, we find that this region of the galaxy is dominated by\nold (t$>$10Gyr) stellar populations. Using the NIR, we find the nucleus to be\ndominated by old stellar populations, and a circumnuclear ring with younger\n($\\sim$2.5Gyr) stars. We also combined the optical and NIR datacubes and\nperformed a panchromatic spatially resolved stellar population synthesis, which\nresulted in a dominance of older stellar populations, in agreement with optical\nresults. We argue that the technique of combining optical and NIR data might be\nuseful to isolate the contribution of stellar population ages with strong NIR\nabsorption bands. We also derive the stellar kinematics and find that the\nstellar motions are dominated by a high ($\\sim$240km$\\cdot$s$^{-1}$) velocity\ndispersion in the nucleus, with stars also rotating around the center. Lastly,\nwe measure the absorption bands, both in the optical and in the NIR, and find a\nnuclear drop in their equivalent widths. The favored explanation for this drop\nis a featureless continuum emission from the low luminosity active galactic\nnucleus." }, { "anchor": "Nebular C IV 1550 Imaging of the Metal-Poor Starburst Mrk 71: Direct\n Evidence of Catastrophic Cooling: We use the Hubble Space Telescope ACS camera to obtain the first spatially\nresolved, nebular imaging in the light of C IV 1548,1551 by using the F150LP\nand F165LP filters. These observations of the local starburst Mrk 71 in NGC\n2366 show emission apparently originating within the interior cavity around the\ndominant super star cluster (SSC), Knot A. Together with imaging in He II 4686\nand supporting STIS FUV spectroscopy, the morphology and intensity of the C IV\nnebular surface brightness and the C IV / He II ratio map provide direct\nevidence that the mechanical feedback is likely dominated by catastrophic\nradiative cooling, which strongly disrupts adiabatic superbubble evolution. The\nimplied extreme mass loading and low kinetic efficiency of the cluster wind are\nreasonably consistent with the wind energy budget, which is probably enhanced\nby radiation pressure. In contrast, the Knot B SSC lies within a well-defined\nsuperbubble with associated soft X-rays and He II 1640 emission, which are\nsignatures of adiabatic, energy-driven feedback from a supernova-driven\noutflow. This system lacks clear evidence of C IV from the limb-brightened\nshell, as expected for this model, but the observations may not be deep enough\nto confirm its presence. We also detect a small C IV-emitting object that is\nlikely an embedded compact H II region. Its C IV emission may indicate the\npresence of very massive stars (> 100 M_sun) or strongly pressure-confined\nstellar feedback.", "positive": "High-resolution near-infrared spectroscopy of globular cluster and field\n stars toward the Galactic bulge: Globular clusters (GCs) play an important role in the formation and evolution\nof the Milky Way. New candidates are continuously found, particularly in the\nhigh-extinction low-latitude regions of the bulge, although their existence and\nproperties have yet to be verified. In order to investigate the new GC\ncandidates, we performed high-resolution NIR spectroscopy of stars toward the\nbulge using the IGRINS instrument at the Gemini-South telescope. We selected 15\nand 10 stars near Camargo 1103 and 1106, respectively, which have recently been\nreported as metal-poor GC candidates in the bulge. In contrast to the classical\napproaches used in optical spectroscopy, we determined stellar parameters from\na combination of line-depth ratios and the equivalent width of a CO line. The\nstellar parameters of the stars follow the common trends of nearby APOGEE stars\nin a similar magnitude range. We also determined the abundances of Fe, Na, Mg,\nAl, Si, S, K, Ca, Ti, Cr, Ni, and Ce through spectrum synthesis. There is no\nclear evidence of a grouping in RV-[Fe/H] space that would indicate the\ncharacterization of either object as metal-poor GCs. This result emphasizes the\nnecessity of follow-up spectroscopy for new GC candidates toward the bulge,\nalthough we cannot completely rule out a low probability that we only observed\nnonmember stars. We also note discrepancies between the abundances of Al, Ca,\nand Ti when derived from the H- vs. the K-band spectra. Although the cause of\nthis discrepancy is not clear, the effects of atmosphere parameters or NLTE are\ndiscussed. Our approach and results demonstrate that IGRINS spectroscopy is a\nuseful tool for studying the chemical properties of stars toward the Galactic\nbulge with a statistical uncertainty in [Fe/H] of 0.03 dex, while the\nsystematic error through uncertainties of atmospheric parameter is slightly\nlarger than in measurements from optical spectroscopy." }, { "anchor": "NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows: We address the origin of Ultra-Diffuse Galaxies (UDGs), which have stellar\nmasses typical of dwarf galaxies but effective radii of Milky Way-sized\nobjects. Their formation mechanism, and whether they are failed $\\rm L_{\\star}$\ngalaxies or diffuse dwarfs, are challenging issues. Using zoom-in cosmological\nsimulations from the NIHAO project, we show that UDG analogues form naturally\nin medium-mass haloes due to episodes of gas outflows associated with star\nformation. The simulated UDGs live in isolated haloes of masses $10^{10-11}\\rm\nM_{\\odot}$, have stellar masses of $10^{7-8.5}\\rm M_{\\odot}$, effective radii\nlarger than 1 kpc and dark matter cores. They show a broad range of colors, an\naverage S\\'ersic index of 0.83, a typical distribution of halo spin and\nconcentration, and a non-negligible HI gas mass of $10^{7-9}\\rm M_{\\odot}$,\nwhich correlates with the extent of the galaxy. Gas availability is crucial to\nthe internal processes that form UDGs: feedback driven gas outflows, and\nsubsequent dark matter and stellar expansion, are the key to reproduce faint,\nyet unusually extended, galaxies. This scenario implies that UDGs represent a\ndwarf population of low surface brightness galaxies and should exist in the\nfield. The largest isolated UDGs should contain more HI gas than less extended\ndwarfs of similar $\\rm M_{\\star}$.", "positive": "The H$\u03b1$ kinematics of interacting galaxies in 12 compact groups: We present new Fabry-Perot observations for a sample of 42 galaxies located\nin twelve compact groups of galaxies: HCG 1, HCG 14, HCG 25, HCG 44, HCG 53,\nHCG 57, HCG 61, HCG 69, HCG 93, VV 304, LGG 455 and Arp 314. From the 42\nobserved galaxies, a total of 26 objects are spiral galaxies, which range from\nSa to Im morphological types. The remaining 16 objects are E, S0 and S0a\ngalaxies. Using these observations, we have derived velocity maps,\nmonochromatic and velocity dispersion maps for 24 galaxies, where 18 are\nspiral, three are S0a, two are S0 and one is an Im galaxy. From the 24 velocity\nfields obtained, we could derive rotation curves for 15 galaxies; only two of\nthem exhibit rotation curves without any clear signature of interactions. Based\non kinematic information, we have evaluated the evolutionary stage of the\ndifferent groups of the current sample. We identify groups that range from\nhaving no H$\\alpha$ emission to displaying an extremely complex kinematics,\nwhere their members display strongly perturbed velocity fields and rotation\ncurves. In the case of galaxies with no H$\\alpha$ emission, we suggest that\npast galaxy interactions removed their gaseous components, thereby quenching\ntheir star formation. However, we can not discard that the lack of H$\\alpha$\nemission is linked with the detection limit for some of our observations." }, { "anchor": "The distribution of open clusters in the Galaxy: In this work we explore the new catalog of galactic open clusters that became\navailable recently, containing 1750 clusters that have been re-analysed using\nthe Gaia DR2 catalog to determine the stellar memberships. We used the young\nopen clusters as tracers of spiral arms and determined the spiral pattern\nrotation speed of the Galaxy and the corotation radius, the strongest Galactic\nresonance. The sample of open clusters used here increases the last one from\nDias et al. (2019) used in the previous determination of the pattern speed by\ndozens objects. In addition, the distances and ages values are better\ndetermined, using improvements to isochrone fitting and including an updated\nextinction polynomial for the Gaia DR2 photometric band-passes, and the\nGalactic abundance gradient as a prior for metallicity. In addition to the\nbetter age determinations, the catalog contains better positions in the\nGalactic plane and better proper motions. This allow us to discuss not only the\npresent space distribution of the clusters, but also the space distribution of\nthe clusters's birthplaces, obtained by integration of the orbits for a time\nequal to their age. The value of the rotation velocity of the arms ($28.5 \\pm\n1.0$ km s$^{-1}$ kpc$^{-1}$) implies that the corotation radius ($R_c$) is\nclose to the solar Galactic orbit ($R_c/R_0 = 1.01\\pm0.08$), which is supported\nby other observational evidence discussed in this text. A simulation is\npresented, illustrating the motion of the clusters in the reference frame of\ncorotation. We also present general statistics of the catalog of clusters, like\nspatial distribution, distribution relative to height from the Galactic plane,\nand distribution of ages and metallicity. An important feature of the space\ndistribution, the corotation gap in the gas distribution and its consequences\nfor the young clusters, is discussed.", "positive": "Red Supergiants in M31: The Humphreys-Davidson limit at high metallicity: The empirical upper limit to Red Supergiant (RSG) luminosity, known as the\nHumphreys-Davidson (HD) limit, has been commonly explained as being caused by\nthe stripping of stellar envelopes by metallicity-dependent, line-driven winds.\nAs such, the theoretical expectation is that the HD limit should be higher at\nlower metallicity, where weaker mass-loss rates mean that higher initial masses\nare required for an envelope to be stripped. In this paper, we test this\nprediction by measuring the luminosity function of RSGs in M31 and comparing to\nthose in the LMC and SMC. We find that $\\log (L_{\\rm max}/L_{\\odot}) = 5.53 \\pm\n0.03$ in M31 (Z $\\gtrsim$ Z$_{\\odot}$), consistent with the limit found for\nboth the LMC (Z $\\sim$ 0.5 Z$_{\\odot}$) and SMC (Z $\\sim$ 0.25 Z$_{\\odot}$),\nwhile the RSG luminosity distributions in these 3 galaxies are consistent to\nwithin 1$\\sigma$. We therefore find no evidence for a metallicity dependence on\nboth the HD limit and the RSG luminosity function, and conclude that\nline-driven winds on the main sequence are not the cause of the HD limit." }, { "anchor": "High-precision Photometric Redshifts from Spitzer/IRAC: Extreme\n [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9: One of the most challenging aspects of studying galaxies in the z>~7 universe\nis the infrequent confirmation of their redshifts through spectroscopy, a\nphenomenon thought to occur from the increasing opacity of the intergalactic\nmedium to Lya photons at z>6.5. The resulting redshift uncertainties inhibit\nthe efficient search for [C II] in z~7 galaxies with sub-mm instruments such as\nALMA, given their limited scan speed for faint lines. One means by which to\nimprove the precision of the inferred redshifts is to exploit the potential\nimpact of strong nebular emission lines on the colors of z~4-8 galaxies as\nobserved by Spitzer/IRAC. At z~6.8, galaxies exhibit IRAC colors as blue as\n[3.6]-[4.5] ~-1, likely due to the contribution of [O III]+Hb to the 3.6 mum\nflux combined with the absence of line contamination in the 4.5 mum band. In\nthis paper we explore the use of extremely blue [3.6]-[4.5] colors to identify\ngalaxies in the narrow redshift window z~6.6-6.9. When combined with an\nI-dropout criterion, we demonstrate that we can plausibly select a relatively\nclean sample of z~6.8 galaxies. Through a systematic application of this\nselection technique to our catalogs from all five CANDELS fields, we identify\n20 probable z~6.6-6.9 galaxies. We estimate that our criteria select the ~50%\nstrongest line emitters at z~6.8 and from the IRAC colors we estimate a typical\n[O III]+Hb rest-frame equivalent width of 1085A for this sample. The small\nredshift uncertainties on our sample make it particularly well suited for\nfollow-up studies with facilities such as ALMA.", "positive": "Nearly all the sky is covered by Lyman-alpha emission around high\n redshift galaxies: Galaxies are surrounded by large reservoirs of gas, mostly hydrogen, fed by\ninflows from the intergalactic medium and by outflows due to galactic winds.\nAbsorption-line measurements along the sightlines to bright and rare background\nquasars indicate that this circumgalactic medium pervades far beyond the extent\nof starlight in galaxies, but very little is known about the spatial\ndistribution of this gas. A new window into circumgalactic environments was\nrecently opened with the discovery of ubiquitous extended Lyman-alpha emission\nfrom hydrogen around high-redshift galaxies, facilitated by the extraordinary\nsensitivity of the MUSE instrument at the ESO Very Large Telescope. Due to the\nfaintness of this emission, such measurements were previously limited to\nespecially favourable systems or to massive statistical averaging. Here we\ndemonstrate that low surface brightness Lyman-alpha emission surrounding faint\ngalaxies at redshifts between 3 and 6 adds up to a projected sky coverage of\nnearly 100%. The corresponding rate of incidence (the mean number of\nLyman-alpha emitters penetrated by any arbitrary line of sight) is well above\nunity and similar to the incidence rate of high column density absorbers\nfrequently detected in the spectra of distant quasars. This similarity suggests\nthat most circumgalactic atomic hydrogen at these redshifts has now been\ndetected also in emission." }, { "anchor": "Wavelength-dependent UV photodesorption of pure N2 and O2 ices: Ultraviolet photodesorption of molecules from icy interstellar grains can\nexplain observations of cold gas in regions where thermal desorption is\nnegligible. This non-thermal desorption mechanism should be especially\nimportant where UV fluxes are high. N2 and O2 are expected to play key roles in\nastrochemical reaction networks, both in the solid state and in the gas phase.\nMeasurements of the wavelength-dependent photodesorption rates of these two\ninfrared-inactive molecules provide astronomical and physical-chemical insights\ninto the conditions required for their photodesorption. Tunable radiation from\nthe DESIRS beamline at the SOLEIL synchrotron in the astrophysically relevant 7\nto 13.6 eV range is used to irradiate pure N2 and O2 thin ice films.\nPhotodesorption of molecules is monitored through quadrupole mass spectrometry.\nAbsolute rates are calculated by using the well-calibrated CO photodesorption\nrates. Strategic N2 and O2 isotopolog mixtures are used to investigate the\nimportance of dissociation upon irradiation. N2 photodesorption mainly occurs\nthrough excitation of the b^1Pi_u state and subsequent desorption of surface\nmolecules. The observed vibronic structure in the N2 photodesorption spectrum,\ntogether with the absence of N3 formation, supports that the photodesorption\nmechanism of N2 is similar to CO, i.e., an indirect DIET (Desorption Induced by\nElectronic Transition) process without dissociation of the desorbing molecule.\nIn contrast, O2 photodesorption in the 7 - 13.6 eV range occurs through\ndissociation and presents no vibrational structure. Photodesorption rates of N2\nand O2 integrated over the far-UV field from various star-forming environments\nare lower than for CO. Rates vary between 10E-3 and 10E-2 photodesorbed\nmolecules per incoming photon.", "positive": "Accurate OH maser positions II. the Galactic Center region: We present high spatial resolution observations of ground-state OH masers,\nachieved using the Australia Telescope Compact Array (ATCA). These observations\nwere conducted towards 171 pointing centres, where OH maser candidates were\nidentified previously in the Southern Parkes Large-Area Survey in Hydroxyl\n(SPLASH) towards the Galactic Center region, between Galactic longitudes of\n$355^{\\circ}$ and $5^{\\circ}$ and Galactic latitudes of $-2^{\\circ}$ and\n$+2^{\\circ}$. We detect maser emission towards 162 target fields and suggest\nthat 6 out of 9 non-detections are due to intrinsic variability. Due to the\nsuperior spatial resolution of the follow-up ATCA observations, we have\nidentified 356 OH maser sites in the 162 of the target fields with maser\ndetections. Almost half (161 of 356) of these maser sites have been detected\nfor the first time in these observations. After comparing the positions of\nthese 356 maser sites to the literature, we find that 269 (76\\%) sites are\nassociated with evolved stars (two of which are planetary nebulae), 31 (9\\%)\nare associated with star formation, four are associated with supernova remnants\nand we were unable to determine the origin of the remaining 52 (15\\%) sites.\nUnlike the pilot region (\\citealt{Qie2016a}), the infrared colors of evolved\nstar sites with symmetric maser profiles in the 1612 MHz transition do not show\nobvious differences compared with those of evolved star sites with asymmetric\nmaser profiles." }, { "anchor": "The metallicity and star formation activity of long gamma-ray burst\n hosts for z$<$3: insights from the Illustris simulation: We study the properties of long gamma-ray bursts (LGRBs) using a large scale\nhydrodynamical cosmological simulation, the Illustris simulation. We determine\nthe LGRB host populations under different thresholds for the LGRB progenitor\nmetallicities, according to the collapsar model. We compare the simulated\nsample of LGRBs hosts with recent, largely unbiased, host samples: BAT6 and\nSHOALS. We find that at $z<1$ simulated hosts follow the mass-metallicity\nrelation and the fundamental metallicity relation simultaneously, but with a\npaucity of high-metallicity hosts, in accordance with observations. We also\nfind a clear increment in the mean stellar mass of LGRB hosts and their SFR\nwith redshift up to $z<3$ on account of the metallicity dependence of\nprogenitors. We explore the possible origin of LGRBs in metal rich galaxies,\nand find that the intrinsic metallicity dispersion in galaxies could explain\ntheir presence. LGRB hosts present a tighter correlation between galaxy\nmetallicity and internal metallicity dispersion compared to normal star forming\ngalaxies. We find that the Illustris simulations favours the existence of a\nmetallicity threshold for LGRB progenitors in the range 0.3 - 0.6 Z$_\\odot$", "positive": "The POlarised GLEAM Survey (POGS) I: First Results from a Low-Frequency\n Radio Linear Polarisation Survey of the Southern Sky: The low-frequency polarisation properties of radio sources are poorly\nstudied, particularly in statistical samples. However, the new generation of\nlow-frequency telescopes, such as the Murchison Widefield Array (MWA; the\nprecursor for the low-frequency component of the Square Kilometre Array) offers\nan opportunity to probe the physics of radio sources at very low radio\nfrequencies. In this paper, we present a catalogue of linearly-polarised\nsources detected at 216 MHz, using data from the Galactic and Extragalactic\nAll-sky MWA (GLEAM) survey. Our catalogue covers the Declination range\n$-17^{\\circ}$ to $-37^{\\circ}$ and 24 hours in Right Ascension, at a resolution\nof around 3 arcminutes. We detect 81 sources (including both a known pulsar and\nnew pulsar candidate) with linearly-polarised flux densities in excess of 18\nmJy across a survey area of approximately 6400 square degrees, corresponding to\na surface density of 1 source per 79 square degrees. The level of Faraday\nrotation measured for our sources is broadly consistent with those recovered at\nhigher frequencies, with typically more than an order of magnitude improvement\nin the uncertainty compared to higher-frequency measurements. However, our\ncatalogue is likely incomplete at low Faraday rotation measures, due to our\npractice of excluding sources in the region where instrumental leakage appears.\nThe majority of sources exhibit significant depolarisation compared to higher\nfrequencies; however, a small sub-sample repolarise at 216 MHz. We also discuss\nthe polarisation properties of four nearby, large-angular-scale radio galaxies,\nwith a particular focus on the giant radio galaxy ESO 422$-$G028, in order to\nexplain the striking differences in polarised morphology between 216 MHz and\n1.4 GHz." }, { "anchor": "Dark matter capture by the Sun: revisiting velocity distribution\n uncertainties: Among the different strategies aiming to detect WIMP dark matter (DM), a\nneutrino signal coming from the Sun would be a smoking gun. This possibility\nrelies on the DM capture by the Sun driven by the local DM distribution\nassumptions: the local mass density and the velocity distribution. In this\ncontext, we revisit those astrophysical hypotheses (also relevant for direct\ndetection). We focus especially on the DM velocity distribution considering\ndifferent possibilities beyond the popular Maxwellian distribution. Namely,\nsome alternatives can be considered through analytical approaches and by\nlooking into cosmological simulations of spiral galaxies. Most of the fitting\nformulas used to constrain the local velocity distribution function fail to\ndescribe the peak and the high velocity tail of the velocity distribution\nobserved in simulations, the latter being improved when adding the local escape\nvelocity of DM into the benchmark fitting models. In addition we test the\npredictions by the Eddington inversion method and also illustrate the\nimportance of the galactic dynamical history. We estimate the resulting\nuncertainties on the DM capture rate by the Sun and conclude that different\nvelocity distributions will affect the capture rate of DM by the Sun up to a\n$15-20\\%$. On top of that, the calculation of the intrinsic variance of the\ncapture rate leads to poorly controlled uncertainties especially for high WIMP\nmasses ($>$30 GeV) raising concerns about the capture scenario.", "positive": "NGC 6302: high-ionization permitted lines. Applying X-SSN synthesis to\n VLT-UVES spectra: A preliminary VLT-UVES spectrum of NGC 6302 (Casassus et al. 2002, MN), which\nhosts one of the hottest PN nuclei known (Teff ~ 220000 K; Wright et al. 2011,\nMN), has been recently analysed by means of X-SSN, a spectrum synthesis code\nfor nebulae (Morisset and P\\'equignot). Permitted recombination lines from\nhighly-ionized species are detected/identified for the first time in a PN, and\nsome of them probably for the first time in (Astro)Physics. The need for a\nhomogeneous, high signal-to-noise UVES spectrum for NGC 6302 is advocated." }, { "anchor": "The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). VII.: BCG UV upturn\n and the FUV-NUV color up to redshift 0.35: CONTEXT:At low redshift, early-type galaxies often exhibit a rising flux with\ndecreasing wavelength in the 1000-2500 \\AA{} range, called \"UV upturn\". The\norigin of this phenomenon is debated, and its evolution with redshift is poorly\nconstrained. The observed GALEX FUV-NUV color can be used to probe the UV\nupturn approximately to redshift 0.5. AIMS: We provide constraints on the\nexistence of the UV upturn up to redshift $\\sim$ 0.4 in the brightest cluster\ngalaxies (BCG) located behind the Virgo cluster, using data from the GUViCS\nsurvey. METHODS:We estimate the GALEX far-UV (FUV) and near-UV (NUV) observed\nmagnitudes for BCGs from the maxBCG catalog in the GUViCS fields. We increase\nthe number of nonlocal galaxies identified as BCGs with GALEX photometry from a\nfew tens of galaxies to 166 (64 when restricting this sample to relatively\nsmall error bars). We also estimate a central color within a 20 arcsec\naperture. By using the $r$-band luminosity from the maxBCG catalog, we can\nseparate blue FUV-NUV due to recent star formation and candidate upturn cases.\nWe use Lick indices to verify their similarity to redshift 0 upturn cases.\nRESULTS: We clearly detect a population of blue FUV-NUV BCGs in the redshift\nrange 0.10-0.35, vastly improving the existing constraints at these epochs by\nincreasing the number of galaxies studied, and by exploring a redshift range\nwith no previous data (beyond 0.2), spanning one more Gyr in the past. These\ngalaxies bring new constraints that can help distinguish between assumptions\nconcerning the stellar populations causing the UV upturn phenomenon. The\nexistence of a large number of UV upturns around redshift 0.25 favors the\nexistence of a binary channel among the sources proposed in the literature.", "positive": "Resonant friction on discs in galactic nuclei: We argue that resonant friction has a dramatic effect on a disc whose\nrotation direction is misaligned with that of its host nuclear star cluster.\nThe disc's gravity causes gravitational perturbation of the cluster that in\nturn exerts a strong torque back onto the disc. We argue that this torque may\nbe responsible for the observed disruption of the clockwise disc of young stars\nin the Galactic Center, and show in numerical experiments that it produces the\nobserved features in the distribution of the stars' angular momenta. More\ngenerally, we speculate that the rotation of nuclear star clusters has a\nstabilizing effect on the orientation of transient massive accretion discs\naround the supermassive black holes residing in their centers, and thus on the\ndirections and magnitudes of the black-hole spins." }, { "anchor": "On the mass of the neutron star in Cyg X-2: We present new high resolution spectroscopy of the low mass X-ray binary Cyg\nX-2 which enables us to refine the orbital solution and rotational broadening\nof the donor star. In contrast with Elebert et al (2009) we find a good\nagreement with results reported in Casares et al. (1998). We measure\n$P=9.84450\\pm0.00019$ day, $K_2=86.5\\pm1.2$ km s$^{-1}$ and $V \\sin\ni=33.7\\pm0.9$ km s$^{-1}$. These values imply $q=M_{2}/M_{1}=0.34 \\pm 0.02$ and\n$M_{1}=1.71\\pm 0.21$ M$_{\\odot}$ (for $i=62.5 \\pm 4^{\\circ}$). Therefore, the\nneutron star in Cyg X-2 can be more massive than canonical. We also find no\nevidence for irradiation effects in our radial velocity curve which could\nexplain the discrepancy between Elebert et al's and our $K_2$ values.", "positive": "The Shortest Known Period Star Orbiting our Galaxy's Supermassive Black\n Hole: Stars with short orbital periods at the center of our galaxy offer a powerful\nand unique probe of a supermassive black hole. Over the past 17 years, the W.\nM. Keck Observatory has been used to image the Galactic center at the highest\nangular resolution possible today. By adding to this data set and advancing\nmethodologies, we have detected S0-102, a star orbiting our galaxy's\nsupermassive black hole with a period of just 11.5 years. S0-102 doubles the\nnumber of stars with full phase coverage and periods less than 20 years. It\nthereby provides the opportunity with future measurements to resolve\ndegeneracies in the parameters describing the central gravitational potential\nand to test Einstein's theory of General Relativity in an unexplored regime." }, { "anchor": "Identifying High Metallicity M Giants at Intragroup Distances with SDSS: Tidal stripping and three-body interactions with the central supermassive\nblack hole may eject stars from the Milky Way. These stars would comprise a set\nof `intragroup' stars that trace the past history of interactions in our\ngalactic neighborhood. Using the Sloan Digital Sky Survey DR7, we identify\ncandidate solar metallicity red giant intragroup stars using color cuts that\nare designed to exclude nearby M and L dwarfs. We present 677 intragroup\ncandidates that are selected between 300 kpc and 2 Mpc, and are either the\nreddest intragroup candidates (M7-M10) or are L dwarfs at larger distances than\npreviously detected.", "positive": "Shock-triggered formation of magnetically-dominated clouds. II. Weak\n shock-cloud interaction in three dimensions: To understand the formation of a magnetically dominated molecular cloud from\nan atomic cloud, we study the interaction of a weak, radiative shock with a\nmagnetised cloud. The thermally stable warm atomic cloud is initially in static\nequilibrium with the surrounding hot ionised gas. A shock propagating through\nthe hot medium then interacts with the cloud. We follow the dynamical evolution\nof the shocked cloud with a time-dependent ideal magnetohydrodynamic code. By\nperforming the simulations in 3D, we investigate the effect of different\nmagnetic field orientations including parallel, perpendicular and oblique to\nthe shock normal. We find that the angle between the shock normal and the\nmagnetic field must be small to produce clouds with properties similar to\nobserved molecular clouds." }, { "anchor": "The Ubiquity of Micrometer-Sized Dust Grains in the Dense Interstellar\n Medium: Cold molecular clouds are the birthplaces of stars and planets, where dense\ncores of gas collapse to form protostars. The dust mixed in these clouds is\nthought to be made of grains of an average size of 0.1 micrometer. We report\nthe widespread detection of the coreshine effect as a direct sign of the\nexistence of grown, micrometer-sized dust grains. This effect is seen in half\nof the cores we have analyzed in our survey, spanning all Galactic longitudes,\nand is dominated by changes in the internal properties and local environment of\nthe cores, implying that the coreshine effect can be used to constrain\nfundamental core properties such as the three-dimensional density structure and\nages and also the grain characteristics themselves.", "positive": "Multi-wavelength modelling of the circumstellar environment of the\n massive proto-star AFGL 2591 VLA 3: We have studied the dust density, temperature and velocity distributions of\nthe archetypal massive young stellar object (MYSO) AFGL 2591. Given its high\nluminosity ($L=2 \\times 10^5$ L$_\\odot$) and distance ($d=3.3$ kpc), AFGL 2591\nhas one of the highest $\\sqrt{L}/d$ ratio, giving better resolved dust emission\nthan any other MYSO. As such, this paper provides a template on how to use\nresolved multi-wavelength data and radiative transfer to obtain a\nwell-constrained 2-D axi-symmetric analytic rotating infall model. We show for\nthe first time that the resolved dust continuum emission from Herschel 70\n$\\mu$m observations is extended along the outflow direction, whose origin is\nexplained in part from warm dust in the outflow cavity walls. However, the\nmodel can only explain the kinematic features from CH$_3$CN observations with\nunrealistically low stellar masses ($<15$ M$_\\odot$), indicating that\nadditional physical processes may be playing a role in slowing down the\nenvelope rotation. As part of our 3-step continuum and line fitting, we have\nidentified model parameters that can be further constrained by specific\nobservations. High-resolution mm visibilities were fitted to obtain the disc\nmass (6 M$_\\odot$) and radius (2200 au). A combination of SED and near-IR\nobservations were used to estimate the luminosity and envelope mass together\nwith the outflow cavity inclination and opening angles." }, { "anchor": "EMPRESS. III. Morphology, Stellar Population, and Dynamics of Extremely\n Metal Poor Galaxies (EMPGs): Are EMPGs Local Analogs of High-$z$ Young\n Galaxies?: We present the morphology and stellar population of 27 extremely metal poor\ngalaxies (EMPGs) at $z\\sim0$ with metallicities of 0.01--0.1 Z$_{\\odot}$. We\nconduct multi-component surface brightness (SB) profile fitting for the deep\nSubaru/HSC $i$-band images of the EMPGs with the {\\sc Galfit} software,\ncarefully removing the SB contributions of tails. We find that the EMPGs with a\nmedian stellar mass of $\\log(M_{*}/{\\rm M}_{\\odot})=6.0$ have a median\nS{\\'e}rsic index of $n=1.1$ and a median effective radius of $r_{\\rm e}=200$\npc, suggesting that typical EMPGs have very compact disk. We compare the EMPGs\nwith $z\\sim6$ galaxies and local galaxies on the size-mass ($r_{\\rm e}$-$M_*$)\ndiagram, and identify that the majority of the EMPGs have a $r_{\\rm e}$-$M_*$\nrelation similar to $z\\sim0$ star-forming galaxies rather than $z\\sim6$\ngalaxies. Not every EMPG is a local analog of high-$z$ young galaxies in the\n$r_{\\rm e}$-$M_*$ relation. A spectrum of one pair of EMPG and tail, so far\navailable, indicates that the tail is dynamically related to the EMPG with a\nmedian velocity difference of $\\Delta V=101\\pm32$ km s$^{-1}$. This\nmoderately-large $\\Delta V$ cannot be explained by the dynamics of the tail,\nbut likely by the infall on the tail. For the first time, we may identify the\nmetal-poor star-forming system just now infalling into the tail.", "positive": "A spectroscopic binary in the Hercules dwarf spheroidal galaxy: We present the radial velocity curve of a single-lined spectroscopic binary\nin the faint Hercules dwarf spheroidal (dSph) galaxy, based on 34 individual\nspectra covering more than two years of observations. This is the first time\nthat orbital elements could be derived for a binary in a dSph. The system\nconsists of a metal-poor red giant and a low-mass companion, possibly a white\ndwarf, with a 135-days period in a moderately eccentric ($e=0.18$) orbit. Its\nperiod and eccentricity are fully consistent with metal-poor binaries in the\nGalactic halo, while the projected semimajor axis is small, at $a_p$ sin$i$ =\n38 R$_{sun}$. In fact, a very close orbit could inhibit the production of\nheavier elements through $s$-process nucleosynthesis, leading to the very low\nabundances of neutron-capture elements that are found in this star. We discuss\nthe further implications for the chemical enrichment history of the Hercules\ndSph, but find no compelling binary scenario that could reasonably explain the\nfull, peculiar abundance pattern of the Hercules dSph galaxy." }, { "anchor": "Gravitational contraction versus Supernova driving and the origin of the\n velocity dispersion-size relation in molecular clouds: Molecular cloud observations show that clouds have non-thermal velocity\ndispersions that scale with the cloud size as $\\sigma\\propto R^{1/2}$ at\nconstant surface density, and for varying surface density scale with both the\ncloud`s size and surface density, $\\sigma^2 \\propto R \\Sigma$. The energy\nsource driving these chaotic motions remains poorly understood. We describe the\nvelocity dispersions observed in a cloud population formed in a\nkiloparsec-scale numerical simulation of a magnetized, supernova-driven,\nself-gravitating, interstellar medium, including diffuse heating and radiative\ncooling. We compare the relationships between velocity dispersion, size, and\nsurface density measured in the simulated cloud population to those found in\nobservations of Galactic molecular clouds. We find that external supernova\nexplosions can not drive turbulent motions of the observed magnitudes within\ndense clouds. On the other hand, self-gravity also induces non-thermal motions\nas gravitationally bound clouds begin to collapse in our model, and by doing so\ntheir internal velocity dispersions recover the observed relations. Energy\nconservation suggests that the observed behavior is consistent with the kinetic\nenergy being proportional to the gravitational energy. However, the clouds in\nour model show no sign of reaching a stable equilibrium state at any time, even\nfor strongly magnetized clouds. We conclude that gravitationally bound\nmolecular clouds are always in a state of gravitational collapse and their\nproperties are a natural result of this chaotic collapse. In order to agree\nwith observed star formation efficiencies, this process must be terminated by\nthe early destruction of the clouds, presumably from internal stellar feedback.", "positive": "First results from a study of DIBs with thousands of high-quality\n massive-star spectra: We are using five different surveys to compile the largest sample of diffuse\ninterstellar band (DIB) measurements ever collected. GOSSS is obtaining\nintermediate-resolution blue-violet spectroscopy of ~2500 OB stars, of which\n60% have already been observed and processed. The other four surveys have\nalready collected multi-epoch high-resolution optical spectroscopy of 700 OB\nstars with different telescopes, including the 9 m Hobby-Eberly Telescope in\nMcDonald Observatory. Some of our stars are highly-extinguished targets for\nwhich no good-quality optical spectra have ever been published. For all of the\ntargets in our sample we have obtained accurate spectral types, measured\nnon-DIB ISM lines, and compiled information from the literature to calculate\nthe extinction. Here we present the first results of the project, the\nproperties of twenty DIBs in the 4100-5500 {\\AA} range. We clearly detect a\ncouple of previously elusive DIBs at 4170 {\\AA} and 4591 {\\AA}; the latter\ncould have coronene and ovalene cations as carriers." }, { "anchor": "Optical properties of two complementary samples of intermediate Seyfert\n galaxies: We present preliminary results of the analysis of optical spectra of two\ncomplementary samples of Seyfert galaxies. The first sample was extracted from\na selection of the 4th Fermi Gamma-ray Large Area Telescope (4FGL) catalog, and\nconsists of 9 $\\gamma$-ray emitting jetted Seyfert galaxies. The second one was\nextracted from the Swift-BAT AGN Spectroscopic Survey (BASS), and is composed\nof 38 hard-X ray selected Active Galactic Nuclei (AGN). These two samples are\ncomplementary, with the former expected to have smaller viewing angles, while\nthe latter may include objects with larger viewing angles. We measured emission\nline ratios to investigate whether the behavior of these Seyferts can be\nexplained in terms of obscuration, as suggested by the well-known Unified Model\n(UM) of AGN, or if there are intrinsic differences due to the presence of jets,\noutflows, or the evolution. We found no indications of intrinsic differences.\nThe UM remains the most plausible interpretation for these classes of objects\neven if some results can be challenging for this model.", "positive": "A Dynamically Distinct Stellar Population in the Leading Arm of the\n Sagittarius Stream: We present a chemical and dynamical analysis of the leading arm (LA) and\ntrailing arm (TA) of the Sagittarius (Sgr) stream, as well as for the Sgr dwarf\ngalaxy core (SC), using red giant branch, main sequence, and RR Lyrae stars\nfrom large spectroscopic survey data. The different chemical properties among\nthe LA, TA, and SC generally agree with recent studies, and can be understood\nby radial metallicity gradient established in the progenitor of the Sgr dwarf,\nfollowed by preferential stellar stripping from the outer part of the Sgr\nprogenitor. One striking finding is a relatively larger fraction of\nlow-eccentricity stars (e < 0.4) in the LA than in the TA and SC. The TA and SC\nexhibit very similar distributions. Considering that a tidal tail stripped off\nfrom a dwarf galaxy maintains the orbital properties of its progenitor, we\nexpect that the e-distribution of the LA should be similar to that of the TA\nand SC. Thus, the disparate behavior of the e-distribution of the LA is of\nparticular interest. Following the analysis of Vasiliev et al., we attempt to\nexplain the different e-distribution by introducing a time-dependent\nperturbation of the Milky Way by the Large Magellanic Cloud (LMC)'s\ngravitational pull, resulting in substantial evolution of the angular momentum\nof the LA stars to produce the low-e stars. In addition, we confirm from RR\nLyrae stars with high eccentricity (e > 0.6) that the TA stars farther away\nfrom the SC are also affected by disturbances from the LMC." }, { "anchor": "Star Clusters in the Galactic tidal field, from birth to dissolution: We study the evolution of star clusters in the Galactic tidal field starting\nfrom their birth in molecular clumps. Our model clusters form according to the\nlocal-density-driven cluster formation model in which the stellar density\nprofile is steeper than that of gas. As a result, clusters resist the gas\nexpulsion better than predicted by earlier models.\n We vary the impact of the Galactic tidal field {\\lambda}, considering\ndifferent Galactocentric distances (3-18 kpc), as well as different cluster\nsizes. Our model clusters survive the gas expulsion independent of {\\lambda}.\n We investigated the relation between the cluster mass at the onset of secular\nevolution and their dissolution time. The model clusters formed with a high\nstar-formation efficiency (SFE) follow a tight mass-dependent dissolution\nrelation, in agreement with previous theoretical studies. However, the low-SFE\nmodels present a shallower mass-dependent relation than high-SFE clusters, and\nmost dissolve before reaching 1 Gyr (cluster teenage mortality).", "positive": "The stellar initial mass function at 0.9$10$^{11}$Msun) we find an average age of\n1.7$\\pm$0.3 Gyr and a bottom-heavy IMF ($\\Gamma_b$=3.2$\\pm$0.2). Lighter MQGs\n(2$\\times$10$^{10}$$<$M$<$10$^{11}$ Msun) at the same redshift are younger on\naverage (1.0$\\pm$0.2 Gyr) and present a shallower IMF slope\n($\\Gamma_b=2.7^{+0.3}_{-0.4}$). Our results are in good agreement with the\nfindings about the IMF slope in early-type galaxies of similar mass in the\npresent-day Universe. This suggests that the IMF, a key characteristic of the\nstellar populations in galaxies, is bottom-heavier for more massive galaxies\nand has remained unchanged in the last $\\sim$8 Gyr." }, { "anchor": "First M87 Event Horizon Telescope Results. IV. Imaging the Central\n Supermassive Black Hole: We present the first Event Horizon Telescope (EHT) images of M87, using\nobservations from April 2017 at 1.3 mm wavelength. These images show a\nprominent ring with a diameter of ~40 micro-as, consistent with the size and\nshape of the lensed photon orbit encircling the \"shadow\" of a supermassive\nblack hole. The ring is persistent across four observing nights and shows\nenhanced brightness in the south. To assess the reliability of these results,\nwe implemented a two-stage imaging procedure. In the first stage, four teams,\neach blind to the others' work, produced images of M87 using both an\nestablished method (CLEAN) and a newer technique (regularized maximum\nlikelihood). This stage allowed us to avoid shared human bias and to assess\ncommon features among independent reconstructions. In the second stage, we\nreconstructed synthetic data from a large survey of imaging parameters and then\ncompared the results with the corresponding ground truth images. This stage\nallowed us to select parameters objectively to use when reconstructing images\nof M87. Across all tests in both stages, the ring diameter and asymmetry\nremained stable, insensitive to the choice of imaging technique. We describe\nthe EHT imaging procedures, the primary image features in M87, and the\ndependence of these features on imaging assumptions.", "positive": "On the size distribution of supernova remnants in the Magellanic Clouds: The physical sizes of supernova remnants (SNRs) in a number of nearby\ngalaxies follow an approximately linear cumulative distribution, contrary to\nwhat is expected for decelerating shock fronts. This has been attributed to\nselection effects, or to a majority of SNRs propagating in \"free expansion\", at\nconstant velocity, into a tenuous ambient medium. We compile a list of 77 known\nSNRs in the Magellanic Clouds (MCs), and argue that they are a fairly complete\nrecord of the SNe that have exploded over the last ~20kyr, with most now in the\nadiabatic, Sedov phase of their expansions. The roughly linear cumulative size\ndistribution (uniform in a differential distribution) can result from the\ncombination of a deceleration during this phase, a transition to a\nradiation-loss-dominated phase at a radius that depends on the local gas\ndensity, and a distribution of ambient densities varying roughly as rho^{-1}.\nThis explanation is supported by the observed -1 power-law distributions of\nthree independent tracers of density: HI column density, Halpha surface\nbrightness, and star formation rate from resolved stellar populations. In this\npicture, the observed cutoff at r~30 pc in the SNR size distribution is due to\na minimum in the mean ambient gas density in the regions where supernovae (SNe)\nexplode. We show that M33 has a SNR size distribution similar to that of the\nMCs, suggesting these features, and their explanation, may be universal. In a\ncompanion paper (Maoz & Badenes 2010), we use our sample of SNRs as an\neffective \"SN survey\" to calculate the SN rate and delay time distribution in\nthe MCs. The hypothesis that most SNRs are in free expansion, rather than in\nthe Sedov phase of their evolution, would result in SN rates that are in strong\nconflict with independent measurements, and with basic stellar evolution\ntheory." }, { "anchor": "Stellar Dynamical Modeling - Accuracy of 3D Density Estimation for\n Edge-on Axisymmetric Galaxies: From Rybicki's analysis using the Fourier slice theorem, mathematically it is\npossible to reproduce uniquely an edge-on axisymmetric galaxy's 3D light\ndistribution from its 2D surface brightness. Utilizing galaxies from a\ncosmological simulation, we examine the ability of Syer and Tremaine's\nmade-to-measure method and Schwarzschild's method for stellar dynamical\nmodeling to do so for edge-on oblate axisymmetric galaxies. Overall, we find\nthat the methods do not accurately recover the 3D distributions, with the\nmade-to-measure method producing more accurate estimates than Schwarzschild's\nmethod. Our results have implications broader than just luminosity density, and\naffect other luminosity-weighted distributions within galaxies, for example,\nage and metallicity.", "positive": "The Effects of Radial Migration on the Vertical Structure of Galactic\n Discs: We present evidence that isolated growing discs, subject to internal spiral\nperturbations, thicken due to both heating \\emph{and} radial migration. We show\nthis by demonstrating that the thickness and vertical velocity dispersions of\ncoeval stars depend on their age as well as the change in their radii. While\nthe disc thickens due to internal processes, we find that this induces only a\nminor amount of flaring. We further demonstrate the consequences of such\nthickening on the structural properties of stellar populations and find that\nthey qualitatively agree with recent studies of the Milky Way disc." }, { "anchor": "Short GRB Host Galaxies I: Photometric and Spectroscopic Catalogs, Host\n Associations, and Galactocentric Offsets: We present a comprehensive optical and near-infrared census of the fields of\n90 short gamma-ray bursts (GRBs) discovered in 2005-2021, constituting all\nshort GRBs for which host galaxy associations are feasible ($\\approx$ 60% of\nthe total Swift short GRB population). We contribute 245 new multi-band imaging\nobservations across 49 distinct GRBs and 25 spectra of their host galaxies.\nSupplemented by literature and archival survey data, the catalog contains 335\nphotometric and 40 spectroscopic data sets. The photometric catalog reaches\n$3\\sigma$ depths of $\\gtrsim 24-27$ mag and $\\gtrsim 23-26$ mag for the optical\nand near-infrared bands, respectively. We identify host galaxies for 84 bursts,\nin which the most robust associations make up 54% (49/90) of events, while only\na small fraction, 6.7%, have inconclusive host associations. Based on new\nspectroscopy, we determine 17 host spectroscopic redshifts with a range of\n$z\\approx 0.15-1.6$ and find that $\\approx$ 25-44% of Swift short GRBs\noriginate from $z>1$. We also present the galactocentric offset catalog for 83\nshort GRBs. Taking into account the large range of individual measurement\nuncertainties, we find a median of projected offset of $\\approx 7.9$ kpc, for\nwhich the bursts with the most robust associations have a smaller median of\n$\\approx 4.9$ kpc. Our catalog captures more high-redshift and low-luminosity\nhosts, and more highly-offset bursts than previously found, thereby\ndiversifying the population of known short GRB hosts and properties. In terms\nof locations and host luminosities, the populations of short GRBs with and\nwithout detectable extended emission are statistically indistinguishable. This\nsuggests that they arise from the same progenitors, or from multiple\nprogenitors which form and evolve in similar environments. All of the data\nproducts are available on the BRIGHT website.", "positive": "LinKS: Discovering galaxy-scale strong lenses in the Kilo-Degree Survey\n using Convolutional Neural Networks: We present a new sample of galaxy-scale strong gravitational-lens candidates,\nselected from 904 square degrees of Data Release 4 of the Kilo-Degree Survey\n(KiDS), i.e., the \"Lenses in the Kilo-Degree Survey\" (LinKS) sample. We apply\ntwo Convolutional Neural Networks (ConvNets) to $\\sim88\\,000$ colour-magnitude\nselected luminous red galaxies yielding a list of 3500 strong-lens candidates.\nThis list is further down-selected via human inspection. The resulting LinKS\nsample is composed of 1983 rank-ordered targets classified as \"potential lens\ncandidates\" by at least one inspector. Of these, a high-grade subsample of 89\ntargets is identified with potential strong lenses by all inspectors.\nAdditionally, we present a collection of another 200 strong lens candidates\ndiscovered serendipitously from various previous ConvNet runs. A\nstraightforward application of our procedure to future Euclid or LSST data can\nselect a sample of $\\sim3000$ lens candidates with less than 10 per cent\nexpected false positives and requiring minimal human intervention." }, { "anchor": "The Anisotropic Circumgalactic Medium of Massive Early-Type Galaxies: Using measurements of the [O III], H$\\alpha$ and [N II] emission line fluxes\noriginating in the cool (T $\\sim10^4$ K) gas that populates the halos of\nmassive early-type galaxies with stellar mass greater than $10^{10.4}$\nM$_\\odot$, we explore the recent conjecture that active galactic nucleus (AGN)\nactivity preferentially removes the circumgalactic medium (CGM) along the polar\n(minor-axis) direction. We find deficits in the mean emission line flux of [O\nIII] and H$\\alpha$ (65 and 43%, respectively) along the polar vs. planar\ndirections, although due to the large uncertainties in these difficult\nmeasurements the results are of marginal statistical significance\n(1.5$\\sigma$). More robustly (97 to 99.9% confidence depending on the\nstatistical test), diagnostic line ratios show stronger AGN ionization\nsignatures along the polar direction at small radii than at other angles or\nradii. Our results are consistent with the conjecture of an anisotropic CGM in\nmassive, early type galaxies, suggested on independent grounds, that is tied to\nAGN activity and begin to show the potential of CGM mapping using emission\nlines.", "positive": "The Stormy Life of Galaxy Clusters: astro version: Galaxy clusters form from the infall of dark and baryonic matter at the\nintersection of cosmic filaments. Most of the baryons are in the form of a hot,\nmagnetized, intracluster plasma detected through its X-ray thermal\nbremsstrahlung emission. This plasma is tightly coupled to a second, cosmic ray\nplasma, detected through its synchrotron radio emission. Together, the\nproperties of these plasmas encode the history of the cluster's formation and\nprovide a snapshot of the ongoing cluster evolution. This article provides an\noverview for the more general astrophysical and space plasma community of the\ndynamical processes revealed by the diffuse plasma emissions." }, { "anchor": "Understanding the early stages of galaxy formation using very metal-poor\n stars from the Hamburg/ESO survey: We explore the chemo-dynamical properties of a sample of very metal-poor\n(VMP) stars selected from the Hamburg/ESO survey, matched with Gaia EDR3, in\nthe phase-space identified by the three integrals of motion ($L_z$, $E$,\n$I_3$). Disk and halo orbits are separated by using the criteria defined in\nCarollo et al. (2021). We found 26 stars with $[Fe/H] \\leq -2.5$ possessing\ndisk kinematics, of which 14 are extremely metal-poor. At these metallicities,\nthe number of stars with disk kinematics is three times its retrograde\ncounterpart. In the same range of metallicity we also identified 37 halo stars\nmost tightly bound to the gravitational potential of the progenitor halo. The\norigin of these stars are investigated by comparing the observational results\nwith simulated galaxies from the Aquarius Project and the IllustrisTNG\nsimulations. We found two mechanisms of formation of VMP stars with disk\nkinematics: accretion from early satellites (which is dominant), and {\\it\nin-situ} formation. These stars are very old, with ages > 12.5 Gyr ($z$ > 5),\nand they are $\\alpha$-enriched. Accretion and {\\it in-situ} formation are also\nfound for the retrograde counterparts with being accretion also the dominant\nmode. Contributing accreted satellites have stellar masses in the range\n$[10^{6}-10^9]$ M_sun, and are very gas-rich. The most bound halo stars are the\noldest detected with a median age of ~ 13.3 Gyr ($z$ ~ 11), and\n$\\alpha$-enriched. Our finding clearly show that very old, very metal-poor\nstars store important information on the first stages of assembly of our Galaxy\nand its halo.", "positive": "Andromeda's Parachute: A Bright Quadruply Lensed Quasar at z=2.377: We present Keck Cosmic Web Imager spectroscopy of the four putative images of\nthe lensed quasar candidate J014709+463037 recently discovered by Berghea et\nal. (2017). The data verify the source as a quadruply lensed, broad\nabsorption-line quasar having z_S = 2.377 +/- 0.007. We detect intervening\nabsorption in the FeII 2586, 2600, MgII 2796, 2803, and/or CIV 1548, 1550\ntransitions in eight foreground systems, three of which have redshifts\nconsistent with the photometric-redshift estimate reported for the lensing\ngalaxy (z_L ~ 0.57). By virtue of their positions on the sky, the source images\nprobe these absorbers over transverse physical scales of ~0.3-21 kpc,\npermitting assessment of the variation in metal-line equivalent width W_r as a\nfunction of sight-line separation. We measure differences in W_r,2796 of <40%\nacross all sight-line pairs subtending 7-21 kpc, suggestive of a high degree of\nspatial coherence for MgII-absorbing material. W_r,2600 is observed to vary by\n>50% over the same scales across the majority of sight-line pairs, while CIV\nabsorption exhibits a wide range in W_r,1548 differences of ~5-80% within\ntransverse distances less than ~3 kpc. J014709+463037 is one of only a handful\nof z > 2 quadruply lensed systems for which all four source images are very\nbright (r = 15.4-17.7 mag) and are easily separated in ground-based seeing\nconditions. As such, it is an ideal candidate for higher-resolution\nspectroscopy probing the spatial variation in the kinematic structure and\nphysical state of intervening absorbers." }, { "anchor": "Sensitive Observations of Radio Recombination Lines in Orion and W51:\n The Data and Detection of Systematic Recombination Line Blueshifts\n Proportional to Impact Broadening: Sensitive spectral observations made in two frequency bands near 6.0 and 17.6\nGHz are described for Orion and W51. Using frequency switching we were able to\nachieve a dynamic range in excess of 10,000 without fitting sinusoidal or\npolynomial baselines. This enabled us to detect lines as weak as T$_{A} ~1mK in\nthese strong continuum sources. Hydrogen recombination lines with $\\Delta n$ as\nhigh as 25 have been detected in Orion. In the Orion data, where the lines are\nstronger, we have also detected a systematic shift in the line center\nfrequencies proportional to linewidth that cannot be explained by normal\noptical depth effects.", "positive": "The Spatially-Resolved Star Formation History of the M31 Outer Disc: We present deep Hubble Space Telescope Advanced Camera for Surveys\nobservations of the stellar populations in two fields lying at 20 and 23 kpc\nfrom the centre of M31 along the south-west semi-major axis. These data enable\nthe construction of colour-magnitude diagrams reaching the oldest main-sequence\nturn-offs (~13 Gyr) which, when combined with another field at 25 kpc from our\nprevious work, we use to derive the first precision constraints on the\nspatially-resolved star formation history of the M31 disc. The star formation\nrates exhibit temporal as well as field-to-field variations, but are generally\nalways within a factor of two of their time average. There is no evidence of\ninside-out growth over the radial range probed. We find a median age of ~7.5\nGyr, indicating that roughly half of the stellar mass in the M31 outer disc was\nformed before z ~ 1. We also find that the age-metallicity relations (AMRs) are\nsmoothly increasing from [Fe/H]~-0.4 to solar metallicity between 10 and 3 Gyr\nago, contrary to the flat AMR of the Milky Way disc at a similar number of\nscale lengths. Our findings provide insight on the roles of stellar feedback\nand radial migration in the formation and evolution of large disc galaxies." }, { "anchor": "The binarity of Milky Way F,G,K stars as a function of effective\n temperature and metallicity: We estimate the fraction of F,G,K stars with close binary companions by\nanalysing multi-epoch stellar spectra from SDSS and LAMOST for radial velocity\n(RV) variations. We employ a Bayesian method to infer the maximum likelihood of\nthe fraction of binary stars with orbital periods of 1000 days or shorter,\nassuming a simple model distribution for a binary population with circular\norbits. The overall inferred fraction of stars with such a close binary\ncompanion is 43.0% \\pm 2.0% for a sample of F, G, K stars from SDSS SEGUE, and\n30% \\pm 8.0% in a similar sample from LAMOST. The apparent close binary\nfraction decreases with the stellar effective temperature. We divide the SEGUE\nand LEGUE data into three subsamples with different metallicity ([Fe/H] < -1.1;\n-1.1 < [Fe/H] < -0.6; -0.6 < [Fe/H]), for which the inferred close binary\nfractions are 56% \\pm 5.0%, 56.0% \\pm 3%, and 30% \\pm 5.7%. The metal-rich\nstars from our sample are therefore substantially less likely to possess a\nclose binary companion than otherwise similar stars drawn from metal-poor\npopulations. The different ages and formation environments of the Milky Way's\nthin disk, thick disk and halo may contribute to explaining these observations.\nAlternatively metallicity may have a significant effect on the formation and/or\nevolution of binary stars.", "positive": "Dust Properties of 870 Micron Selected Galaxies in the GOODS-S: We analyze the dust properties of 57 870 $\\mu$m selected dusty star-forming\ngalaxies in the GOODS-S using new deep ALMA 1.2 mm, 2 mm, and 3 mm continuum\nimaging together with other far-infrared through millimeter data. We fit the\nspectral energy distributions (SEDs) with optically thin modified blackbodies\nto constrain the emissivity indices and effective dust temperatures, finding a\nmedian emissivity index of $\\beta = 1.78^{+0.43}_{-0.25}$ and a median\ntemperature of $T_d = 33.6^{+12.1}_{-5.4}$ K. We observe a negative correlation\nbetween $\\beta$ and $T_d$. By testing several SED models, we determine that the\nderived emissivity indices can be influenced by opacity assumptions. Our\ntemperature measurements are consistent with no evolution in dust temperature\nwith redshift." }, { "anchor": "Are Compton-Thick AGN the Missing Link Between Mergers and Black Hole\n Growth?: We examine the host morphologies of heavily obscured active galactic nuclei\n(AGN) at $z\\sim1$ to test whether obscured supermassive black hole growth at\nthis epoch is preferentially linked to galaxy mergers. Our sample consists of\n154 obscured AGN with $N_{\\rm H}>10^{23.5}$ cm$^{-2}$ and $z<1.5$. Using visual\nclassifications, we compare the morphologies of these AGN to control samples of\nmoderately obscured ($10^{22}$ cm$^{-2}$ $54.4$eV versus lower energies. This\nsuggests that the impact of high energy photons from binary stars is reduced\nwhen accounting for an energy dependent escape fraction.", "positive": "Observational determination of the galaxy bias from cosmic variance with\n a random pointing survey: Clustering of z~2 galaxies from Hubble's BoRG\n survey: Gravitational clustering broadens the count-in-cells distribution of galaxies\nfor surveys along uncorrelated (well-separated) lines of sight beyond Poisson\nnoise. A number of methods have proposed to measure this excess \"cosmic\"\nvariance to constrain the galaxy bias (i.e. the strength of clustering)\nindependently of the two-point correlation function. Here we present an\nobservational application of these methods using data from 141 uncorrelated\nfields (~700 arcmin$^2$ total) from Hubble's Brightest of Reionizing Galaxies\n(BoRG) survey. We use BoRG's broad-band imaging in optical and near infrared to\nidentify N~1000 photometric candidates at z~2 through a combination of colour\nselection and photometric redshift determination, building a magnitude-limited\nsample with $m_{AB}\\leq24.5$ in F160W. We detect a clear excess in the variance\nof the galaxy number counts distribution compared to Poisson expectations, from\nwhich we estimate a galaxy bias $b \\approx 3.63 \\pm 0.57$. When divided by\nSED-fit classification into ~400 early-type and ~600 late-type candidates, we\nestimate biases of $b_{early} \\approx 4.06 \\pm 0.67$ and $b_{late} \\approx 2.98\n\\pm 0.98$ respectively. These estimates are consistent with previous\nmeasurements of the bias from the two-point correlation function, and\ndemonstrate that with $N\\gtrsim100$ sight-lines, each containing $N\\gtrsim5$\nobjects, the counts-in-cell analysis provides a robust measurement of the bias.\nThis implies that the method can be applied effectively to determine clustering\nproperties (and characteristic dark-matter halo masses) of z~6-9 galaxies from\na pure-parallel James Webb Space Telescope survey similar in design to Hubble's\nBoRG survey." }, { "anchor": "The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System\n and Implications for Magellanic Irregulars: We present a novel pair of numerical models of the interaction history\nbetween the Large and Small Magellanic Clouds (LMC and SMC, respectively) and\nour Milky Way (MW) in light of recent high precision proper motions\n(Kallivayalil et al. 2006a,b). Given the new velocities, cosmological\nsimulations of structure formation favor a scenario where the Magellanic Clouds\n(MCs) are currently on their first infall towards our Galaxy (Boylan-Kolchin et\nal. 2011, Busha et al. 2011). We illustrate here that the observed irregular\nmorphology and internal kinematics of the MCs (in gas and stars) are naturally\nexplained by interactions between the LMC and SMC, rather than gravitational\ninteractions with the MW. This picture further supports a first infall scenario\n(Besla et a. 2007). In particular, we demonstrate that the Magellanic Stream, a\nband of HI gas trailing behind the MCs 150 degrees across the sky, can be\naccounted for by the action of LMC tides on the SMC before the system was\naccreted by the MW. We further demonstrate that the off-center, warped stellar\nbar of the LMC and its one-armed spiral, can be naturally explained by a recent\ndirect collision with the SMC. Such structures are key morphological\ncharacteristics of a class of galaxies referred to as Magellanic Irregulars (de\nVaucouleurs & Freeman 1972), the majority of which are not associated with\nmassive spiral galaxies. We infer that dwarf-dwarf galaxy interactions are\nimportant drivers for the morphological evolution of Magellanic Irregulars and\ncan dramatically affect the efficiency of baryon removal from dwarf galaxies\nvia the formation of extended tidal bridges and tails. Such interactions are\nimportant not only for the evolution of dwarf galaxies but also have direct\nconsequences for the buildup of baryons in our own MW, as LMC-mass systems are\nbelieved to be the dominant building blocks of MW-type halos.", "positive": "The SAMI Galaxy Survey: Spatially Resolving the Main Sequence of Star\n Formation: We present the ~800 star formation rate maps for the SAMI Galaxy Survey based\non H{\\alpha} emission maps, corrected for dust attenuation via the Balmer\ndecrement, that are included in the SAMI Public Data Release 1. We mask out\nspaxels contaminated by non-stellar emission using the [O III]/H{\\beta}, [N\nII]/H{\\alpha}, [S II]/H{\\alpha}, and [O I]/H{\\alpha} line ratios. Using these\nmaps, we examine the global and resolved star-forming main sequences of SAMI\ngalaxies as a function of morphology, environmental density, and stellar mass.\nGalaxies further below the star-forming main sequence are more likely to have\nflatter star formation profiles. Early-type galaxies split into two populations\nwith similar stellar masses and central stellar mass surface densities. The\nmain sequence population has centrally-concentrated star formation similar to\nlate-type galaxies, while galaxies >3{\\sigma} below the main sequence show\nsignificantly reduced star formation most strikingly in the nuclear regions.\nThe split populations support a two-step quenching mechanism, wherein halo mass\nfirst cuts off the gas supply and remaining gas continues to form stars until\nthe local stellar mass surface density can stabilize the reduced remaining fuel\nagainst further star formation. Across all morphologies, galaxies in denser\nenvironments show a decreased specific star formation rate from the outside in,\nsupporting an environmental cause for quenching, such as ram-pressure stripping\nor galaxy interactions." }, { "anchor": "The evolution of Lithium: implications of a universal Spite plateau: The cosmological {7Li problem consists in explaining why the primordial Li\nabundance, as predicted by the standard Big Bang nucleosynthesis theory with\nconstraints from WMAP and Planck, is a factor of 3 larger than the Li abundance\nmeasured in the stars of the Spite plateau defined by old, warm dwarf stars of\nthe Milky Way halo. Several explanations have been proposed to explain this\ndifference, including various Li depletion processes as well as non standard\nBig Bang nucleosynthesis, but the main question remains unanswered. In this\npaper, we present detailed chemical evolution models for dwarf spheroidal and\nultra faint galaxies, compute the galactic evolution of 7Li abundance in these\nobjects and compare it with observations of similar objects. In our models, Li\nis mainly produced by novae and cosmic rays and to a minor extent by low and\nintermediate mass stars. We adopt the yield combination which best fits the Li\nabundances in the Milky Way stars. It is evident that the observations of dwarf\nobjects define a Spite plateau, identical to that observed in the Milky Way,\nthus suggesting that the Spite plateau could be a universal feature and its\nmeaning should be discussed. The predictions of our models for dwarf galaxies,\nare obtained by assuming as Li primordial abundance either the one detected in\nthe atmospheres of the oldest halo stars (Spite plateau; A(Li)=2.2 dex), or the\none from cosmological observations (WMAP; A(Li)=2.66 dex). Finally, we discuss\nthe implications of the universality of the Spite plateau results.", "positive": "The question of selective absorption of light in space viewed from the\n viewpoint of the dynamics of the universe: The selective light absorption in space has been raised in astronomical\nliterature. The substance producing the absorption must have some mass; thus\nthe question is how large it is. We develop a dynamical model of the Milky Way\nsystem, assuming that it can be represented by a flattened ellipsoid of\nrotation. We use the spatial distribution of $\\delta$-Cephei and Algol type\nvariable stars, and mean velocities of stars according to Campbell to calculate\nthe dynamical density of the Milky Way near the Sun, $0.100\\,M_\\odot/pc^3$. We\nfind that the dynamical density is equal to the mean density of stars in the\nvicinity of the Sun. Our conclusion is that the intrinsic gravity of stars\nfully explains their motion, and the existence of any other matter in any\nsignificant quantity seems unlikely. Therefore, the existence of noticeable\nselective absorption seems to be absolutely improbable, unless one admits the\nexistence in the space of particles much smaller than atoms of elements known\nto us. Normal absorption may exist if the particle diameter is of the order of\na millimetre or less, and their mass is comparatively small. This absorption\nhas not yet been reliably detected; the fact that the number of stars increases\nwith stellar magnitude more slowly than theory requires in case of uniform\ndistribution of stars in space, can be equally explained by both light\nabsorption and decrease in number of stars with distance." }, { "anchor": "An ALMA study of the massive molecular clump N159W-North in the Large\n Magellanic Cloud: A possible gas flow penetrating one of the most massive\n protocluster systems in the Local Group: Massive dense clumps in the Large Magellanic Cloud can be an important\nlaboratory to explore the formation of populous clusters. We report multiscale\nALMA observations of the N159W-North clump, which is the most CO-intense region\nin the galaxy. High-resolution CO isotope and 1.3 mm continuum observations\nwith an angular resolution of $\\sim$0.\"25($\\sim$0.07 pc) revealed more than\nfive protostellar sources with CO outflows within the main ridge clump. One of\nthe thermal continuum sources, MMS-2, shows especially massive/dense nature\nwhose total H$_2$ mass and peak column density are $\\sim$10$^{4}$ $M_{\\odot}$\nand $\\sim$10$^{24}$ cm$^{-2}$, respectively, and harbors massive ($\\sim$100\n$M_{\\odot}$) starless core candidates identified as its internal substructures.\nThe main ridge containing this source can be categorized as one of the most\nmassive protocluster systems in the Local Group. The CO high-resolution\nobservations found several distinct filamentary clouds extending southward from\nthe star-forming spots. The CO (1-0) data set with a larger field of view\nreveals a conical-shaped, $\\sim$30 pc long complex extending toward the\nnorthern direction. These features indicate that a large-scale gas compression\nevent may have produced the massive star-forming complex. Based on the striking\nsimilarity between the N159W-North complex and the previously reported other\ntwo high-mass star-forming clouds in the nearby regions, we propose a\n$\"$teardrops inflow model$\"$ that explains the synchronized, extreme star\nformation across $>$50 pc, including one of the most massive protocluster\nclumps in the Local Group.", "positive": "Fluctuating feedback-regulated escape fraction of ionizing radiation in\n low-mass, high-redshift galaxies: Low mass galaxies are thought to provide the bulk of the ionizing radiation\nnecessary to reionize the Universe. The amount of photons escaping the galaxies\nis poorly constrained theoretically, and difficult to measure observationally.\nYet it is an essential parameter of reionization models. We study in detail how\nionizing radiation can leak from high redshift galaxies. For this purpose, we\nuse a series of high resolution radiation hydrodynamics simulations, zooming on\nthree dwarf galaxies in a cosmological context. We find that the energy and\nmomentum input from the supernova explosions has a pivotal role in regulating\nthe escape fraction, by disrupting dense star forming clumps, and clearing\nsight lines in the halo. In the absence of supernovae, photons are absorbed\nvery locally, within the birth clouds of massive stars. We follow the time\nevolution of the escape fraction, and find that it can vary by more than six\norders of magnitude. This explains the large scatter in the value of the escape\nfraction found by previous studies. This fast variability also impacts the\nobservability of the sources of reionization: a survey even as deep as $M_{\\rm\nUV} = -14$ would miss about half of the underlying population of\nLyman-continuum emitters." }, { "anchor": "COSMOS2020: The cosmic evolution of the stellar-to-halo mass relation\n for central and satellite galaxies up to z~5: We use the COSMOS2020 catalogue to measure the stellar-to-halo mass relation\n(SHMR) divided by central and satellite galaxies from $z=0.2$ to $z = 5.5$.\nStarting from accurate photometric redshifts we measure the near-infrared\nselected two-point angular correlation and stellar mass functions in ten\nredshift bins and fit them with an HOD-based model. At each redshift, we\nmeasure the ratio of stellar mass to halo mass, $M_*/M_h$, which shows the\ncharacteristic strong dependence of halo mass with a peak at $M_h^{\\rm peak}\n\\sim 10^{12}\\, M_{\\odot}$. Our results are in accordance with the scenario in\nwhich the peak of star-formation efficiency moves towards more massive halos at\nhigher redshifts. We also measure the fraction of satellites as a function of\nstellar mass and redshift. For all stellar mass thresholds the satellite\nfraction decreases at higher redshifts. At a given redshift there is a higher\nfraction of low-mass satellites. The satellite contribution to the total\nstellar mass budget in halos becomes more important than centrals at halo\nmasses of about $M_h > 10^{13} \\, M_{\\odot}$ and always stays below by peak,\nindicating that quenching mechanisms are present in massive halos that keep the\nstar-formation efficiency low. Finally, we compare our results with three\nhydrodynamical simulations Horizon-AGN, Illustris-TNG-100 and EAGLE. We find\nthat the most significant discrepancy is at the high mass end, where the\nsimulations generally show that satellites have a higher contribution to the\ntotal stellar mass budget than the observations. This, together with the\nfinding that the fraction of satellites is higher in the simulations, indicates\nthat the feedback mechanisms acting in group-and cluster-scale halos appear to\nbe less efficient in quenching the mass assembly of satellites, and/or that\nquenching occurs much later in the simulations.", "positive": "Observing AGN feedback with CO intensity mapping: Current models of galaxy formation require star formation in high-mass\ngalaxies to be limited by poorly understood mechanisms of quasar feedback.\nFeedback processes can be studied by examining the molecular gas content of AGN\nhosts through the CO rotational ladder, but the complexity of these\nobservations means that current data are limited to only extremely CO-bright\nobjects. Upcoming CO intensity mapping experiments offer an opportunity for a\nless biased probe of quasar feedback. By correlating intensity maps with\nspectroscopic AGN surveys, we can obtain a measurement of the mean CO\nluminosity of a large population of quasars simultaneously. We show that\nexperiments like COMAP, CCAT-prime, and CONCERTO have enough sensitivity to\ndetect this cross-correlation if existing AGN observations are representative\nof the whole population, and to place interesting upper limits if they are not.\nFuture surveys will be able to increase the precision of these measurements by\norders of magnitude, allowing detailed studies of quasar properties across a\nwide range of cosmic history." }, { "anchor": "Optical Linear Polarization toward the Open Star Cluster Casado Alessi 1: We present B-, V-, R-, and I-bands linear polarimetric observations of 73\nstars in the direction of open star cluster Casado Alessi 1 (hereafter Alessi\n1). We aim to use polarimetry as a tool to investigate the properties and\ndistribution of dust grains toward the direction of the cluster. The\npolarimetric observations were carried out using the ARIES IMaging POLarimeter\nmounted at the 104 cm telescope of ARIES, Nainital (India). Using the Gaia\nphotometric data the age and distance of the cluster are estimated to be\n$0.8\\pm0.1$ Gyr and $673\\pm98$ pc, respectively. A total of 66 stars with a 26\narcmin radius from the cluster are identified as members of the cluster using\nthe astrometric approach. Out of these 66 members, 15 stars were observed\npolarimetrically and found to have the same value of polarization. The majority\nof the stars in the region follow the general law of the polarization for the\ninterstellar medium, indicating that polarization toward the cluster Alessi 1\nis dominated by foreground dust grains. The average values of the maximum\npolarization ($P_{max}$) and the wavelength corresponding to the maximum\npolarization ($\\lambda_{max}$) toward the cluster are found to be\n$0.83\\pm0.03$% and $0.59\\pm0.04$ $\\mu$m, respectively. Also, dust grains toward\nthe cluster appear to be aligned, possibly due to the galactic magnetic field.", "positive": "A large-scale kinematic study of molecular gas in high-z cluster\n galaxies: Evidence for high levels of kinematic asymmetry: We investigate the resolved kinematics of the molecular gas, as traced by\nALMA in CO (2-1), of 25 cluster member galaxies across three different clusters\nat a redshift of $z\\sim1.6$. This is the first large-scale analysis of the\nmolecular gas kinematics of cluster galaxies at this redshift. By separately\nestimating the rotation curve of the approaching and receding side of each\ngalaxy via kinematic modeling, we quantify the difference in total circular\nvelocity to characterize the overall kinematic asymmetry of each galaxy. 3/14\nof the galaxies in our sample that we are able to model have similar degrees of\nasymmetry as that observed in galaxies in the field at similar redshift.\nHowever, this leaved 11/14 galaxies in our sample with significantly higher\nasymmetry, and some of these galaxies have degrees of asymmetry of up to\n$\\sim$50 times higher than field galaxies observed at similar redshift. Some of\nthese extreme cases also have one-sided tail-like morphology seen in the\nmolecular gas, supporting a scenario of tidal and/or ram pressure interaction.\nSuch stark differences in the kinematic asymmetry in clusters versus the field\nsuggest the evolutionary influence of dense environments, established as being\na major driver of galaxy evolution at low-redshift, is also active in the\nhigh-redshift universe." }, { "anchor": "Herschel observations of EXtraordinary Sources: Analysis of the full\n Herschel/HIFI molecular line survey of Sagittarius B2(N): A sensitive broadband molecular line survey of the Sagittarius B2(N)\nstar-forming region has been obtained with the HIFI instrument on the Herschel\nSpace Observatory, offering the first high-spectral resolution look at this\nwell-studied source in a wavelength region largely inaccessible from the ground\n(625-157 um). From the roughly 8,000 spectral features in the survey, a total\nof 72 isotopologues arising from 44 different molecules have been identified,\nranging from light hydrides to complex organics, and arising from a variety of\nenvironments from cold and diffuse to hot and dense gas. We present an LTE\nmodel to the spectral signatures of each molecule, constraining the source\nsizes for hot core species with complementary SMA interferometric observations,\nand assuming that molecules with related functional group composition are\ncospatial. For each molecule, a single model is given to fit all of the\nemission and absorption features of that species across the entire 480-1910 GHz\nspectral range, accounting for multiple temperature and velocity components\nwhen needed to describe the spectrum. As with other HIFI surveys toward massive\nstar forming regions, methanol is found to contribute more integrated line\nintensity to the spectrum than any other species. We discuss the molecular\nabundances derived for the hot core, where the local thermodynamic equilibrium\napproximation is generally found to describe the spectrum well, in comparison\nto abundances derived for the same molecules in the Orion KL region from a\nsimilar HIFI survey.", "positive": "Cosmic ray-driven galactic winds: streaming or diffusion?: Cosmic rays (CRs) have recently re-emerged as attractive candidates for\nmediating feedback in galaxies because of their long cooling timescales. They\ncan have energy densities comparable to the thermal gas, but do not suffer\ncatastrophic cooling losses. Recent simulations have shown that the momentum\nand energy deposited by CRs moving with respect to the ambient medium can drive\ngalactic winds. However, simulations are hampered by our ignorance of the\ndetails of CR transport. Two key limits previously considered model CR\ntransport as a purely diffusive process (with a constant diffusion coefficient)\nand as an advective streaming process. With a series of GADGET simulations, we\ncompare and contrast the results of these different assumptions. In idealised\nthree-dimensional galaxy formation models, we show that these two cases result\nin significant differences for the galactic wind mass loss rates and star\nformation suppression in dwarf galaxies with halo masses\n$M\\approx10^{10}\\,\\textrm{M}_\\odot$: diffusive CR transport results in more\nthan ten times larger mass loss rates compared to CR streaming models. We\ndemonstrate that this is largely due to the excitation of Alfv\\'en waves during\nthe CR streaming process that drains energy from the CR population to the\nthermal gas, which is subsequently radiated away. By contrast, CR diffusion\nconserves the CR energy in the absence of adiabatic changes and if CRs are\nefficiently scattered by Alfv\\'en waves that are propagating up the CR\ngradient. Moreover, because pressure gradients are preserved by CR streaming,\nbut not diffusion, the two can have a significantly different dynamical\nevolution regardless of this energy exchange. In particular, the constant\ndiffusion coefficients usually assumed can lead to unphysically high CR fluxes." }, { "anchor": "New candidate hypervelocity red clump stars in the inner Galactic bulge: We search for high-velocity stars in the inner region of the Galactic bulge\nusing a selected sample of red clump stars. Some of those stars might be\nconsidered hypervelocity stars (HVSs). Even though the HVSs ejection relies on\nan interaction with the supermassive black hole (SMBH) at the centre of the\nGalaxy, there are no confirmed detections of HVSs in the inner region of our\nGalaxy. With the detection of HVSs, ejection mechanism models can be\nconstrained by exploring the stellar dynamics in the Galactic centre through a\nrecent stellar interaction with the SMBH. Based on a previously developed\nmethodology by our group, we searched with a sample of preliminary data from\nversion 2 of the Vista Variables in the Via Lactea (VVV) Infrared Astrometric\nCatalogue (VIRAC2) and Gaia DR3 data, including accurate optical and NIR proper\nmotions. This search resulted in a sample of 46 stars with transverse\nvelocities larger than the local escape velocity within the Galactic bulge, of\nwhich 4 are prime candidate HVSs with high-proper motions consistent with being\nejections from the Galactic centre. Adding to that, we studied a sample of\nreddened stars without a Gaia DR3 counterpart and found 481 stars with\ntransverse velocities larger than the local escape velocity, from which 65\nstars have proper motions pointing out of the Galactic centre and are candidate\nHVSs. In total, we found 69 candidate HVSs pointing away from the Galactic\ncentre with transverse velocities larger than the local escape velocity.", "positive": "How can young massive clusters reach their present-day sizes?: The classic question that how young massive star clusters attain their shapes\nand sizes, as we find them today, remains to be a challenge. Both observational\nand computational studies of star-forming massive molecular gas clouds infer\nthat massive cluster formation is primarily triggered along the small-scale\n($\\lesssim0.3$ pc) filamentary substructures within the clouds. The present\nstudy is intended to investigate the possible ways in which a\nfilament-like-compact, massive star cluster (effective radius 0.1-0.3 pc) can\nexpand $\\gtrsim10$ times, still remaining massive enough ($\\gtrsim10^4\nM_\\odot$), to become a young massive star cluster, as we observe today. To that\nend, model massive clusters (of initially $10^4 M_\\odot-10^5 M_\\odot$) are\nevolved using Sverre Aarseth's state-of-the-art N-body code NBODY7. All the\ncomputed clusters expand with time, whose sizes (effective radii) are compared\nwith those observed for young massive clusters, of age $\\lesssim100$ Myr, in\nthe Milky Way and other nearby galaxies. It is found that beginning from the\nabove compact sizes, a star cluster cannot expand by its own, i.e., due to\ntwo-body relaxation, stellar-evolutionary mass loss, dynamical heating by\nprimordial binaries and stellar-mass black holes, up to the observed sizes of\nyoung massive clusters; they always remain much more compact compared to the\nobserved ones. This calls for additional mechanisms that can boost the\nexpansion of a massive cluster after its assembly. Using further N-body\ncalculations, it is shown that a substantial residual gas expulsion, with\n$\\approx30$% star formation efficiency, can indeed swell the newborn embedded\ncluster adequately. The limitations of the present calculations and their\nconsequences are discussed." }, { "anchor": "Evidence for a Young Stellar Population in Nearby Type 1 Active Galaxies: To understand the physical origin of the close connection between\nsupermassive black holes and their host galaxies, it is vital to investigate\nstar formation properties in active galaxies. Using a large dataset of nearby\ntype 1 active galactic nuclei (AGNs) with detailed structural decomposition\nbased on high-resolution optical images obtained with the Hubble Space\nTelescope, we study the correlation between black hole mass and bulge\nluminosity and the (Kormendy) relation between bulge effective radius and\nsurface brightness. In both relations, the bulges of type 1 AGNs tend to be\nmore luminous than those of inactive galaxies with the same black hole mass or\nthe same bulge size. This suggests that the central regions of AGN host\ngalaxies have characteristically lower mass-to-light ratios than inactive\ngalaxies, most likely due to the presence of a younger stellar population in\nactive systems. In addition, the degree of luminosity excess appears to be\nproportional to the accretion rate of the AGN, revealing a physical connection\nbetween stellar growth and black hole growth. Adopting a simple toy model for\nthe increase of stellar mass and black hole mass, we show that the fraction of\nyoung stellar population flattens out toward high accretion rates, possibly\nreflecting the influence of AGN-driven feedback.", "positive": "Peculiarities in Velocity Dispersion and Surface Density Profiles of\n Star Clusters: Based on our recent work on tidal tails of star clusters (Kuepper et al.\n2009) we investigate star clusters of a few 10^4 Msun by means of velocity\ndispersion profiles and surface density profiles. We use a comprehensive set of\n$N$-body computations of star clusters on various orbits within a realistic\ntidal field to study the evolution of these profiles with time, and ongoing\ncluster dissolution From the velocity dispersion profiles we find that the\npopulation of potential escapers, i.e. energetically unbound stars inside the\nJacobi radius, dominates clusters at radii above about 50% of the Jacobi\nradius. Beyond 70% of the Jacobi radius nearly all stars are energetically\nunbound. The velocity dispersion therefore significantly deviates from the\npredictions of simple equilibrium models in this regime. We furthermore argue\nthat for this reason this part of a cluster cannot be used to detect a dark\nmatter halo or deviations from Newtonian gravity. By fitting templates to the\nabout 10^4 computed surface density profiles we estimate the accuracy which can\nbe achieved in reconstructing the Jacobi radius of a cluster in this way. We\nfind that the template of King (1962) works well for extended clusters on\nnearly circular orbits, but shows significant flaws in the case of eccentric\ncluster orbits. This we fix by extending this template with 3 more free\nparameters. Our template can reconstruct the tidal radius over all fitted\nranges with an accuracy of about 10%, and is especially useful in the case of\ncluster data with a wide radial coverage and for clusters showing significant\nextra-tidal stellar populations. No other template that we have tried can yield\ncomparable results over this range of cluster conditions. All templates fail to\nreconstruct tidal parameters of concentrated clusters, however. (abridged)" }, { "anchor": "IMF-induced intrinsic uncertainties on measuring galaxy distances based\n on the number of giant stars: the case of the ultra-diffuse galaxy NGC\n 1052-DF2: The surface brightness fluctuation (SBF) technique is one of the distance\nmeasurement methods that has been applied on the low surface brightness galaxy\nNGC 1052-DF2 yielding a distance of about 20 Mpc implying it to be a dark\nmatter deficient galaxy. We assume the number of giant stars above a given\nluminosity threshold to represent the SBF magnitude. The SBF magnitude depends\non the distance, but this is degenerate with the star formation history (SFH).\nUsing a stellar population synthesis model we calculate the number of giant\nstars for stellar populations with different galaxy-wide stellar initial mass\nfunctions (gwIMFs), ages, metallicities and SFHs. If the gwIMF is the invariant\ncanonical IMF, the 1$\\sigma$ (3$\\sigma$) uncertainty in colour allows a\ndistance as low as 12 Mpc (8 Mpc). If instead the true underlying gwIMF is the\nintegrated galaxy-wide IMF (IGIMF) then overestimating distances for low-mass\ngalaxies would be a natural result, allowing NGC 1052-DF2 to have a distance of\n11 Mpc within the 1$\\sigma$ colour uncertainty. Finally, we show that our main\nconclusion on the existence of a bias in the SBF distance estimation is not\nmuch affected by changing the luminosity lower limit for counting giant stars.", "positive": "X-QUEST: A Comprehensive X-ray Study of Local ULIRGs and QSOs: We present results from the X-ray portion of a multi-wavelength study of\nlocal ULIRGs and QSOs called QUEST (Quasar-ULIRG Evolution STudy). The data\nconsist of new and archival X-ray data on 40 ULIRGs and 26 PG QSOs taken with\nChandra and XMM-Newton. A combination of traditional and hardness ratio\nspectral fitting methods is used to characterize the X-ray properties of these\nobjects. The absorption-corrected 2-10 keV to bolometric luminosity ratios of\nthe ULIRGs and PG QSOs suggest that the likelihood for dominant nuclear\nactivity increases along the merger sequence from \"cool\" ULIRGs, \"warm\" ULIRGs,\ninfrared-bright QSOs, and infrared-faint QSOs. The starburst dominates the\ntotal power in ULIRGs prior to the merger, and this is followed by rapid black\nhole growth during and after coalescence. These results are in general\nagreement with those obtained in the mid-infrared with Spitzer and recent\nnumerical simulations." }, { "anchor": "Galactic nuclei evolution with spinning black holes: method and\n implementation: Supermassive black holes at the centre of galactic nuclei mostly grow in mass\nthrough gas accretion over cosmic time. This process also modifies the angular\nmomentum (or spin) of black holes, both in magnitude and in orientation.\nDespite being often neglected in galaxy formation simulations, spin plays a\ncrucial role in modulating accretion power, driving jet feedback, and\ndetermining recoil velocity of coalescing black hole binaries. We present a new\naccretion model for the moving-mesh code {\\sc arepo} that incorporates (i) mass\naccretion through a thin $\\alpha$-disc, and (ii) spin evolution through the\nBardeen-Petterson effect. We use a diverse suite of idealised simulations to\nexplore the physical connection between spin evolution and larger scale\nenvironment. We find that black holes with mass $\\lesssim 10^{7}$ M$_{\\odot}$\nexperience quick alignment with the accretion disc. This favours prolonged\nphases of spin-up, and the spin direction evolves according to the gas inflow\non timescales as short as $\\lesssim 100$ Myr, which might explain the observed\njet direction distribution in Seyfert galaxies. Heavier black holes ($\\gtrsim\n10^{8}$ M$_{\\odot}$) are instead more sensitive to the local gas kinematic.\nHere we find a wider distribution in spin magnitudes: spin-ups are favoured if\ngas inflow maintains a preferential direction, and spin-downs occur for nearly\nisotropic infall, while the spin direction does not change much over short\ntimescales $\\sim 100$ Myr. We therefore conclude that supermassive black holes\nwith masses $\\gtrsim 5 \\times 10^{8}$ M$_{\\odot}$ may be the ideal testbed to\ndetermine the main mode of black hole fuelling over cosmic time.", "positive": "VEGAS: a VST Early-type GAlaxy Survey. IV. NGC 1533, IC 2038 and IC\n 2039: an interacting triplet in the Dorado group: This paper focuses on NGC 1533 and the pair IC 2038 and IC 2039 in Dorado a\nnearby, clumpy, still un-virialized group. We obtained their surface photometry\nfrom deep OmegaCAM@ESO-VST images in g and r bands. For NGC 1533, we map the\nsurface brightness down to $\\mu_g \\simeq 30.11$ mag/arcsec$^{2}$ and $\\mu_r\n\\simeq 28.87$ mag/arcsec$^{2}$ and out to about $4R_e$. At such faint levels\nthe structure of NGC 1533 appear amazingly disturbed with clear structural\nasymmetry between inner and outer isophotes in the North-East direction. We\ndetect new spiral arm-like tails in the outskirts, which might likely be the\nsignature of a past interaction/merging event. Similarly, IC 2038 and IC 2039\nshow tails and distortions indicative of their ongoing interaction. Taking\nadvantages of deep images, we are able to detect the optical counterpart to the\nHI gas. The analysis of the new deep data suggests that NGC 1533 had a complex\nhistory made of several interactions with low-mass satellites that generated\nthe star-forming spiral-like structure in the inner regions and are shaping the\nstellar envelope. In addition, the VST observations show that also the two less\nluminous galaxies, IC 2038 and IC 2039, are probably interacting each-other\nand, in the past, IC 2038 could have also interacted with NGC 1533, which\nstripped away gas and stars from its outskirts. The new picture emerging from\nthis study is of an interacting triplet, where the brightest galaxy NGC 1533\nhas ongoing mass assembly in the outskirts." }, { "anchor": "The anticentre old open clusters Berkeley 27, Berkeley 34, and Berkeley\n 36: new additions to the BOCCE project: In this paper we present the investigation of the evolutionary status of\nthree open clusters: Berkeley 27, Berkeley 34, and Berkeley 36, all located in\nthe Galactic anti-centre direction. All of them were observed with SUSI2@NTT\nusing the Bessel B, V, and I filters. The cluster parameters have been obtained\nusing the synthetic colour-magnitude diagram (CMD) method i.e. the direct\ncomparison of the observational CMDs with a library of synthetic CMDs generated\nwith different evolutionary sets (Padova, FRANEC, and FST). This analysis shows\nthat Berkeley 27 has an age between 1.5 and 1.7 Gyr, a reddening E(B-V) in the\nrange 0.40 and 0.50, and a distance modulus (m-M)_0 between 13.1 and 13.3;\nBerkeley 34 is older with an age in the range 2.1 and 2.5 Gyr, E(B-V) between\n0.57 and 0.64, and (m-M)_0 between 14.1 and 14.3; Berkeley 36, with an age\nbetween 7.0 and 7.5 Gyr, has a reddening E(B-V)~0.50 and a distance modulus\n(m-M)_0 between 13.1 and 13.2. For all the clusters our analysis suggests a\nsub-solar metallicity in accord with their position in the outer Galactic disc.", "positive": "The Density Variance Mach Number Relation in the Taurus Molecular Cloud: Supersonic turbulence in molecular clouds is a key agent in generating\ndensity enhancements that may subsequently go on to form stars. The stronger\nthe turbulence - the higher the Mach number - the more extreme the density\nfluctuations are expected to be. Numerical models predict an increase in\ndensity variance with rms Mach number of the form: sigma^{2}_{rho/rho_{0}} =\nb^{2}M^{2}, where b is a numerically-estimated parameter, and this prediction\nforms the basis of a large number of analytic models of star formation. We\nprovide an estimate of the parameter b from 13CO J=1-0 spectral line imaging\nobservations and extinction mapping of the Taurus molecular cloud, using a\nrecently developed technique that needs information contained solely in the\nprojected column density field to calculate sigma^{2}_{rho/rho_{0}}. We find b\n~ 0.48, which is consistent with typical numerical estimates, and is\ncharacteristic of turbulent driving that includes a mixture of solenoidal and\ncompressive modes. More conservatively, we constrain b to lie in the range\n0.3-0.8, depending on the influence of sub-resolution structure and the role of\ndiffuse atomic material in the column density budget. We also report a break in\nthe Taurus column density power spectrum at a scale of ~1pc, and find that the\nbreak is associated with anisotropy in the power spectrum. The break is\nobserved in both 13CO and dust extinction power spectra, which, remarkably, are\neffectively identical despite detailed spatial differences between the 13CO and\ndust extinction maps. [ abridged ]" }, { "anchor": "The shape of dark matter haloes: results from weak lensing in the\n Ultraviolet Near-Infrared Optical Northern Survey (UNIONS): Cold dark matter haloes are expected to be triaxial, and so appear elliptical\nin projection. We use weak gravitational lensing from the Canada-France Imaging\nSurvey (CFIS) component of the Ultraviolet-Near Infrared Optical Northern\nSurvey (UNIONS) to measure the ellipticity of the dark matter haloes around\nLuminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey Data Release 7\n(DR7) and from the CMASS and LOWZ samples of the Baryon Oscillation\nSpectroscopic Survey (BOSS), assuming their major axes are aligned with the\nstellar light. We find that DR7 LRGs with masses $M \\sim 2.7\\times10^{13}\n\\mathrm{M}_{\\odot}/h$ have halo ellipticities $e=0.46\\pm0.10$. Expressed as a\nfraction of the galaxy ellipticity, we find $f_h = 2.2\\pm0.6$. For BOSS LRGs,\nthe detection is of marginal significance: $e = 0.20\\pm0.10$ and\n$f_h=0.7\\pm0.7$. These results are in agreement with other measurements of halo\nellipticity from weak lensing and, taken together with previous results,\nsuggest an increase of halo ellipticity of $0.10\\pm0.06$ per decade in halo\nmass. This trend agrees with the predictions from hydrodynamical simulations,\nwhich find that at higher halo masses, not only do dark matter haloes become\nmore elliptical, but that the misalignment between major axis of the stellar\nlight in the central galaxy and that of the dark matter decreases.", "positive": "The Parallax of W43: a Massive Star Forming Complex near the Galactic\n Bar: We report trigonometric parallax measurements of masers in the massive star\nforming complex W43 from VLBA observations as part of the BeSSeL Survey. Based\non measurements of three 12 GHz methanol maser sources (G029.86-00.04,\nG029.95-00.01 and G031.28+00.06) and one 22 GHz water maser source\n(G031.58+00.07) toward W43, we derived a distance of $5.49^{+0.39}_{-0.34}$ kpc\nto W43. By associating the masers with CO molecular clouds, and associating the\nclouds kinematically with CO longitude-velocity spiral features, we assign W43\nto the Scutum spiral arm, close to the near end of the Galactic bar. The\npeculiar motion of W43 is about 20 km/s toward the Galactic Center and is very\nlikely induced by the gravitational attraction of the bar." }, { "anchor": "Copious Amounts of Dust and Gas in a z=7.5 Quasar Host Galaxy: We present IRAM/NOEMA and JVLA observations of the quasar J1342+0928 at\nz=7.54 and report detections of copious amounts of dust and [CII] emission in\nthe interstellar medium (ISM) of its host galaxy. At this redshift, the age of\nthe universe is 690 Myr, about 10% younger than the redshift of the previous\nquasar record holder. Yet, the ISM of this new quasar host galaxy is\nsignificantly enriched by metals, as evidenced by the detection of the [CII]\n158micron cooling line and the underlying far-infrared (FIR) dust continuum\nemission. To the first order, the FIR properties of this quasar host are\nsimilar to those found at a slightly lower redshift (z~6), making this source\nby far the FIR-brightest galaxy known at z>7.5. The [CII] emission is spatially\nunresolved, with an upper limit on the diameter of 7 kpc. Together with the\nmeasured FWHM of the [CII] line, this yields a dynamical mass of the host of\n<1.5x10^11 M_sun. Using standard assumptions about the dust temperature and\nemissivity, the NOEMA measurements give a dust mass of (0.6-4.3)x10^8 M_sun.\nThe brightness of the [CII] luminosity, together with the high dust mass, imply\nactive ongoing star formation in the quasar host. Using [CII]-SFR scaling\nrelations, we derive star formation rates of 85-545 M_sun/yr in the host,\nconsistent with the values derived from the dust continuum. Indeed, an episode\nof such past high star formation is needed to explain the presence of ~10^8\nM_sun of dust implied by the observations.", "positive": "SDSS-IV MaNGA: Evidence for enriched accretion onto satellite galaxies\n in dense environments: We investigate the environmental dependence of the local gas-phase\nmetallicity in a sample of star-forming galaxies from the MaNGA survey.\nSatellite galaxies with stellar masses in the range\n$9<\\log(M_{*}/M_{\\odot})<10$ are found to be $\\sim 0.05 \\, \\mathrm{dex}$ higher\nin metallicity than centrals of similar stellar mass. Within the low-mass\nsatellite population, we find that the interstellar medium (ISM) metallicity\ndepends most strongly on the stellar mass of the galaxy that is central to the\nhalo, though there is no obvious difference in the metallicity gradients. At\nfixed total stellar mass, the satellites of high mass ($M_{*}>10^{10.5} \\,\n\\mathrm{M_{\\odot}}$) centrals are $\\sim 0.1 \\, \\mathrm{dex}$ more metal rich\nthan satellites of low-mass ($M_{*} < 10^{10} \\, \\mathrm{M_{\\odot}}$) centrals,\ncontrolling for local stellar mass surface density and gas fraction. Fitting a\ngas-regulator model to the spaxel data, we are able to account for variations\nin the local gas fraction, stellar mass surface density and local escape\nvelocity-dependent outflows. We find that the best explanation for the\nmetallicity differences is the variation in the average metallicity of accreted\ngas between different environments that depends on the stellar mass of the\ndominant galaxies in each halo. This is interpreted as evidence for the\nexchange of enriched gas between galaxies in dense environments that is\npredicted by recent simulations." }, { "anchor": "An Interference Removal Technique for Radio Pulsar Searches: Searches for radio pulsars are becoming increasingly difficult because of a\nrise in impulsive man-made terrestrial radio-frequency interference. Here we\npresent a new technique, zero-DM filtering, which can significantly reduce the\neffects of such signals in pulsar search data. The technique has already been\napplied to a small portion of the data from the Parkes multi-beam pulsar\nsurvey, resulting in the discovery of four new pulsars, so illustrating its\nefficacy.", "positive": "A Herschel/HIFI Legacy Survey of HF and H2O in the Galaxy: Probing\n Diffuse Molecular Cloud Chemistry: We combine Herschel observations of a total of 12 sources to construct the\nmost uniform survey of HF and H2O in our Galactic disk. Both molecules are\ndetected in absorption along all sight lines. The high spectral resolution of\nthe Heterodyne Instrument for the Far-Infrared (HIFI) allows us to compare the\nHF and H2O distributions in 47 diffuse cloud components sampling the disk. We\nfind that the HF and H2O velocity distributions follow each other almost\nperfectly and establish that HF and H2O probe the same gas-phase volume. Our\nobservations corroborate theoretical predictions that HF is a sensitive tracer\nof H2 in diffuse clouds, down to molecular fractions of only a few percent.\nUsing HF to trace H2 in our sample, we find that the N(H2O)-to-N(HF) ratio\nshows a narrow distribution with a median value of 1.51. Our results further\nsuggest that H2O might be used as a tracer of H2 -within a factor 2.5- in the\ndiffuse interstellar medium. We show that the measured factor of ~2.5 variation\naround the median is driven by true local variations in the H2O abundance\nrelative to H2 throughout the disk. The latter variability allows us to test\nour theoretical understanding of the chemistry of oxygen-bearing molecules in\nthe diffuse gas. We show that both gas-phase and grain-surface chemistry are\nrequired to reproduce our H2O observations. This survey thus confirms that\ngrain surface reactions can play a significant role in the chemistry occurring\nin the diffuse interstellar medium n_H < 1000 cm^-3." }, { "anchor": "Gravitational eigenstates in weak gravity II: further approximate\n methods for decay rates: This paper develops further approximate methods for obtaining the dipole\nmatrix elements and corresponding transition and decay rates of the high-n,\nhigh-l gravitational eigenstates. These methods include (1) investigation of\nthe polar spreads of the angular components of the high-n, high-l eigenstates\nand the effects these have on the limiting values of the angular components of\nthe dipole matrix elements in the case of large l and m and (2) investigation\nof the rapid cut off and limited width of the low-p, high-n radial\neigenfunctions, and the development of an equation to determine the width,\nposition and oscillatory behaviour of those eigenfunctions in cases of\narbitrarily large values of n, l and p. The methods have wider applicability\nthan dipole transition rate estimates and may be also used to determine limits\non the rates for more general interactions. Combining the methods enables the\nestablishment of upper limits to the total dipole decay rates of many high-n,\nlow-p states on the state diagram to be determined, even those that have many\nchannels available for decay. The results continue to support the hypothetical\nexistence of a specialized set of high-n, low-p gravitational eigenfunctions\nthat are invisible and stable, both with respect to electromagnetic decay and\ngravitational collapse, making them excellent dark matter candidates.", "positive": "Multiple channels for nitrogen pollution by metal enriched supermassive\n stars and implications for GN-z11: GN-z11 is an unusually luminous high redshift galaxy which was recently\nobserved to have strong nitrogen lines while at the same time lacking\ntraditional signatures of AGN activity. These observations have been\ninterpreted as a super-solar nitrogen abundance which is challenging to explain\nwith standard stellar evolution and supernovae enrichment. We present\nsimulations of four models of metal enriched supermassive stars after the zero\nage main sequence which produce super-solar nitrogen consistent with the\nobservations of GN-z11. We then show that the most massive model ends its life\nin a violent explosion which results in even greater nitrogen pollution." }, { "anchor": "When the Jeans don't fit: How stellar feedback drives stellar kinematics\n and complicates dynamical modeling in low-mass galaxies: In low-mass galaxies, stellar feedback can drive gas outflows that generate\nnon-equilibrium fluctuations in the gravitational potential. Using cosmological\nzoom-in baryonic simulations from the Feedback in Realistic Environments (FIRE)\nproject, we investigate how these fluctuations affect stellar kinematics and\nthe reliability of Jeans dynamical modeling in low-mass galaxies. We find that\nstellar velocity dispersion and anisotropy profiles fluctuate significantly\nover the course of galaxies' starburst cycles. We therefore predict an\nobservable correlation between star formation rate and stellar kinematics:\ndwarf galaxies with higher recent star formation rates should have systemically\nhigher stellar velocity dispersions. This prediction provides an observational\ntest of the role of stellar feedback in regulating both stellar and dark-matter\ndensities in dwarf galaxies. We find that Jeans modeling, which treats galaxies\nas virialized systems in dynamical equilibrium, overestimates a galaxy's\ndynamical mass during periods of post-starburst gas outflow and underestimates\nit during periods of net inflow. Short-timescale potential fluctuations lead to\ntypical errors of $\\sim 20\\%$ in dynamical mass estimates, even if full\n3-dimensional stellar kinematics -- including the orbital anisotropy -- are\nknown exactly. When orbital anisotropy is $\\textit{not}$ known a priori,\ntypical mass errors arising from non-equilibrium fluctuations in the potential\nare larger than those arising from the mass-anisotropy degeneracy. However,\nJeans modeling alone $\\textit{cannot}$ reliably constrain the orbital\nanisotropy, and problematically, it often favors anisotropy models that do not\nreflect the true profile. If galaxies completely lose their gas and cease\nforming stars, fluctuations in the potential subside, and Jeans modeling\nbecomes much more reliable.", "positive": "A recent update of gas-phase chemical reactions and molecular lines in\n CLOUDY: its effects on millimeter and sub-millimeter molecular line\n predictions: Here we present our current updates of the gas-phase chemical reaction rates\nand molecular lines in the spectral synthesis code CLOUDY, and its implications\nin spectroscopic modelling of various astrophysical environments. We include\nenergy levels, radiative and collisional rates for HF, CF$^+$, HC$_3$N,\nArH$^+$, HCl, HCN, CN, CH, and CH$_2$. Simultaneously, we expand our molecular\nnetwork involving these molecules. For this purpose, we have added 561 new\nreactions and have updated the existing 165 molecular reaction rates involving\nthese molecules. As a result, CLOUDY now predicts all the lines arising from\nthese nine molecules. In addition, we also update H$_2$--H$_2$ collisional data\nup to rotational levels $J$=31 for $v$=0. We demonstrate spectroscopic\nsimulations of these molecules for a few astrophysical environments. Our\nexisting model for globules in the Crab nebula successfully predicts the\nobserved column density of ArH$^+$. Our model predicts a detectable amount of\nHeH$^+$, OH$^+$, and CH$^+$ for the Crab nebula. We also model the ISM towards\nHD185418, W31C, NGC 253, and our predictions match with most of the observed\ncolumn densities within the observed error bars. Very often molecular lines\ntrace various physical conditions. Hence, this update will be very supportive\nfor spectroscopic modelling of various astrophysical environments, particularly\ninvolving sub-millimeter and mid-infrared observations using ALMA and JWST,\nrespectively." }, { "anchor": "A high resolution VLT/FLAMES study of individual stars in the centre of\n the Fornax dwarf spheroidal galaxy: For the first time we show the detailed late-stage chemical evolution history\nof small nearby dwarf spheroidal galaxy in the Local Group. We present the\nresults of a high resolution (R$\\sim$20000) FLAMES/GIRAFFE abundance study at\nESO/VLT of 81 photometrically selected red giant branch stars in the central\n25$'$ of the Fornax dwarf spheroidal galaxy. We present abundances of \\alfe\\\n(Mg, Si, Ca and Ti), iron-peak elements (Fe, Ni and Cr) and heavy elements (Y,\nBa, La, Nd and Eu). Our sample was randomly selected, and is clearly dominated\nby the younger and more metal rich component of Fornax which represents the\nmajor fraction of stars in the central region. This means that the majority of\nour stars are 1$-$4 Gyr old, and thus represent the end phase of chemical\nevolution in this system. Our sample of stars has unusually low [$\\alpha$/Fe],\n[Ni/Fe] and [Na/Fe] compared to the Milky Way stellar populations at the same\n[Fe/H]. The particularly important role of stellar winds from low metallicity\nAGB stars in the creation of s-process elements is clearly seen from the high\n[Ba/Y]. Furthermore, we present evidence for an s-process contribution to Eu.", "positive": "First constraints on the AGN X-ray luminosity function at $z \\sim 6$\n from an eROSITA-detected quasar: We searched for high-z quasars within the X-ray source population detected in\nthe contiguous $\\sim 140^2$ eFEDS field observed by eROSITA during the\nperformance verification phase. We collected the available spectroscopic\ninformation in the field, including the sample of all currently known optically\nselected z>5.5 quasars and cross-matched secure Legacy DR8 counterparts of\neROSITA-detected X-ray point-like sources with this spectroscopic sample. We\nreport the X-ray detection of an eROSITA source securely matched to the\nwell-known quasar SDSS J083643.85+005453.3 (z=5.81). The soft X-ray flux of the\nsource derived from eROSITA is consistent with previous Chandra observations.\nIn addition, we report the detection of the quasar with LOFAR at 145 MHz and\nASKAP at 888 MHz. The reported flux densities confirm a spectral flattening at\nlower frequencies in the emission of the radio core, indicating that the quasar\ncould be a (sub-) gigahertz peaked spectrum source. The inferred spectral shape\nand the parsec-scale radio morphology of SDSS J083643.85+005453.3 suggest that\nit is in an early stage of its evolution into a large-scale radio source or\nconfined in a dense environment. We find no indications for a strong jet\ncontribution to the X-ray emission of the quasar, which is therefore likely to\nbe linked to accretion processes. The detection of this source allows us to\nplace the first constraints on the XLF at z>5.5 based on a secure spectroscopic\nredshift. Compared to extrapolations from lower-redshift observations, this\nfavours a relatively flat slope for the XLF at $z\\sim 6$ beyond $L_*$. The\npopulation of X-ray luminous AGNs at high redshift may be larger than\npreviously thought. From our XLF constraints, we make the conservative\nprediction that eROSITA will detect $\\sim 90$ X-ray luminous AGNs at redshifts\n5.72 using\n VLT and Subaru near-infrared spectroscopy of zCOSMOS galaxies: In the local universe, there is good evidence that, at a given stellar mass\nM, the gas-phase metallicity Z is anti-correlated with the star formation rate\n(SFR) of the galaxies. It has also been claimed that the resulting Z(M,SFR)\nrelation is invariant with redshift - the so-called Fundamental Metallicity\nRelation (FMR). Given a number of difficulties in determining metallicities,\nespecially at higher redshifts, the form of the Z(M,SFR) relation and whether\nit is really independent of redshift is still very controversial. To explore\nthis issue at z>2, we used VLT-SINFONI and Subaru-MOIRCS near-infrared\nspectroscopy of 20 zCOSMOS-deep galaxies at 2.12 galaxies of a given mass\nhave much higher SFRs than the local SDSS galaxies. We find that the zCOSMOS\ngalaxies are consistent with a non-evolving FMR if we use the\nphysically-motivated formulation of the Z(M,SFR) relation from Lilly et al.\n(2003), but not if we use the empirical formulation of Mannucci et al. (2010)." }, { "anchor": "Turbulent dynamo with advective magnetic helicity flux: Many astrophysical bodies harbor magnetic fields that are thought to be\nsustained by a dynamo process. However, it has been argued that the production\nof large-scale magnetic fields by mean-field dynamo action is strongly\nsuppressed at large magnetic Reynolds numbers owing to the conservation of\nmagnetic helicity. This phenomenon is known as {\\it catastrophic quenching}.\nAdvection of magnetic fields by stellar and galactic winds toward the outer\nboundaries and away from the dynamo is expected to alleviate such quenching.\nHere we explore the relative roles played by advective and turbulent--diffusive\nfluxes of magnetic helicity in the dynamo. In particular, we study how the\ndynamo is affected by advection. We do this by performing direct numerical\nsimulations of a turbulent dynamo of $\\alpha^2$ type driven by forced\nturbulence in a Cartesian domain in the presence of a flow away from the\nequator where helicity changes sign. Our results indicate that in the presence\nof advection, the dynamo, otherwise stationary, becomes oscillatory. We confirm\nan earlier result for turbulent--diffusive magnetic helicity fluxes that for\nsmall magnetic Reynolds numbers ($\\Rm\\lesssim 100...200$, based on the\nwavenumber of the energy-carrying eddies) the magnetic helicity flux scales\nless strongly with magnetic Reynolds number ($\\Rm^{-1/2}$) than the term\ndescribing magnetic helicity destruction by resistivity ($\\Rm^{-1}$). Our new\nresults now suggest that for larger $\\Rm$ the former becomes approximately\nindependent of $\\Rm$, while the latter falls off more slowly. We show for the\nfirst time that both for weak and stronger winds, the magnetic helicity flux\nterm becomes comparable to the resistive term for $\\Rm\\gtrsim 1000$, which is\nnecessary for alleviating catastrophic quenching.", "positive": "Exploring the Very Extended Low Surface Brightness Stellar Populations\n of the Large Magellanic Cloud with SMASH: We present the detection of very extended stellar populations around the\nLarge Magellanic Cloud (LMC) out to R~21 degrees, or ~18.5 kpc at the LMC\ndistance of 50 kpc, as detected in the Survey of the MAgellanic Stellar History\n(SMASH) performed with the Dark Energy Camera on the NOAO Blanco 4m Telescope.\nThe deep (g~24) SMASH color magnitude diagrams (CMDs) clearly reveal old (~9\nGyr), metal-poor ([Fe/H]=-0.8 dex) main-sequence stars at a distance of 50 kpc.\nThe surface brightness of these detections is extremely low with our most\ndistant detection having 34 mag per arcsec squared in g-band. The SMASH radial\ndensity profile breaks from the inner LMC exponential decline at ~13-15 degrees\nand a second component at larger radii has a shallower slope with power-law\nindex of -2.2 that contributes ~0.4% of the LMC's total stellar mass. In\naddition, the SMASH densities exhibit large scatter around our best-fit model\nof ~70% indicating that the envelope of stellar material in the LMC periphery\nis highly disturbed. We also use data from the NOAO Source catalog to map the\nLMC main-sequence populations at intermediate radii and detect a steep dropoff\nin density on the eastern side of the LMC (at R~8 deg) as well as an extended\nstructure to the far northeast. These combined results confirm the existence of\na very extended, low-density envelope of stellar material with disturbed shape\naround the LMC. The exact origin of this structure remains unclear but the\nleading options include a classical accreted halo or tidally stripped outer\ndisk material." }, { "anchor": "Genesis of morpho-kinematic lopsidedness in minor merger of galaxies: An $m=1$ lopsided asymmetry is common in disc galaxies. Here, we investigate\nthe excitation of an $m=1$ lopsidedness in host galaxies during minor mergers\nwhile choosing a set of 1:10 merger models (with varying orbital\nconfigurations, morphology of the host galaxy) from the GalMer galaxy merger\nlibrary. We show that a minor merger triggers a prominent $m=1$ lopsidedness in\nstars of the host galaxy. The strength of the $m=1$ lopsidedness undergoes a\ntransient amplification phase after each pericenter passage of the satellite,\nin concordance with past findings of exciting an $m=1$ lopsidedness by tidal\nencounters. However, once the merger happens, and the post-merger remnant\nreadjusts itself, the lopsidedness disappears in short time-scale ($\\sim$\n500-850 Myr). Furthermore, a delayed merger can drive a prolonged ($\\sim$2 Gyr)\nlopsidedness in the host galaxy. We demonstrate that the $m=1$ lopsidedness\nrotates with a well-defined pattern speed which is much slower than the $m=2$\nbar pattern speed, and is retrograde with respect to the bar. This gives rise\nto a dynamical scenario where the Inner Lindblad resonance of the $m=1$\nlopsidedness falls in between the corotation and the Outer Lindblad resonance\nof the $m=2$ bar mode. A kinematic lopsidedness also arises in the host galaxy;\nthe resulting temporal variation closely follows that of the density\nlopsidedness. The minor merger also triggers a transient off-centred stellar\ndisc-dark matter halo configuration due to the tidal encounter with the\nsatellite.", "positive": "A Search for H-Dropout Lyman Break Galaxies at z~12-16: We present two bright galaxy candidates at z~12-13 identified in our\nH-dropout Lyman break selection with 2.3 deg2 near-infrared deep imaging data.\nThese galaxy candidates, selected after careful screening of foreground\ninterlopers, have spectral energy distributions showing a sharp discontinuity\naround 1.7 um, a flat continuum at 2-5 um, and non-detections at <1.2 um in the\navailable photometric datasets, all of which are consistent with z>12 galaxy.\nAn ALMA program targeting one of the candidates shows a tentative 4sigma\n[OIII]88um line at z=13.27, in agreement with its photometric redshift\nestimate. The number density of the z~12-13 candidates is comparable to that of\nbright z~10 galaxies, and is consistent with a recently proposed double\npower-law luminosity function rather than the Schechter function, indicating\nlittle evolution in the abundance of bright galaxies from z~4 to 13.\nComparisons with theoretical models show that the models cannot reproduce the\nbright end of rest-frame ultraviolet luminosity functions at z~10-13. Combined\nwith recent studies reporting similarly bright galaxies at z~9-11 and mature\nstellar populations at z~6-9, our results indicate the existence of a number of\nstar-forming galaxies at z>10, which will be detected with upcoming space\nmissions such as James Webb Space Telescope, Nancy Grace Roman Space Telescope,\nand GREX-PLUS." }, { "anchor": "The JCMT SCUBA-2 Survey of the James Webb Space Telescope North Ecliptic\n Pole Time-Domain Field: The James Webb Space Telescope Time-Domain Field (JWST-TDF) is an $\\sim$14$'$\ndiameter field near the North Ecliptic Pole that will be targeted by one of the\nJWST Guaranteed Time Observations programs. Here, we describe our James Clerk\nMaxwell Telescope SCUBA-2 850 $\\mu$m imaging of the JWST-TDF and present the\nsubmillimeter source catalog and properties. We also present a catalog of radio\nsources from Karl J. Jansky Very Large Array 3 GHz observations of the field.\nThese observations were obtained to aid JWST's study of the dust-obscured\ngalaxies that contribute significantly to the cosmic star formation at high\nredshifts. Our deep 850 $\\mu$m map covers the JWST TDF at a noise level of\n$\\sigma_{850}$ = 1.0 mJy beam$^{-1}$, detecting 83/31 sources in the\nmain/supplementary signal-to-noise ratio (S/N $>$ 4 / S/N = 3.5 - 4) sample\nrespectively. The 3 GHz observations cover a 24$'$ diameter field with a 1\n$\\sigma$ noise of 1$\\mu$Jy beam$^{-1}$ at a 0$.\\!\\!^{\\prime\\prime}$7 FWHM. We\nidentified eighty-five 3 GHz counterparts to sixty-six 850 $\\mu$m sources and\nthen matched these with multiwavelength data from the optical to the\nmid-infrared wave bands. We performed spectral energy distribution fitting for\n61 submillimeter galaxies (SMGs) matched with optical/near-infrared data, and\nfound that SMGs at S/N $>$ 4 have a median value of $z_{phot} = $2.22 $\\pm$\n0.12, star formation rates of 300 $\\pm$ 40 M$_{\\odot}\\,{\\rm yr^{-1}}$ (Chabrier\ninitial mass function), and typical cold dust masses of 5.9 $\\pm$ 0.7 $ \\times$\n10$^{8} $M$_{\\odot}$, in line with bright SMGs from other surveys. The large\ncold dust masses indicate correspondingly large cool gas masses, which we\nsuggest are a key factor necessary to drive the high star formation rates seen\nin this population", "positive": "Microlensing of strongly lensed quasars: Strong gravitational lensing of quasars has the potential to unlock the\npoorly understood physics of these fascinating objects, as well as serve as a\nprobe of the lensing mass distribution and of cosmological parameters. In\nparticular, gravitational microlensing by compact bodies in the lensing galaxy\ncan enable mapping of quasar structure to $\\lt 10^{-6}$ arcsec scales. Some of\nthis potential has been realized over the past few decades, however the\nupcoming era of large sky surveys promises to bring this to full fruition. Here\nwe review the theoretical framework of this field, describe the prominent\ncurrent methods for parameter inference from quasar microlensing data across\ndifferent observing modalities, and discuss the constraints so far derived on\nthe geometry and physics of quasar inner structure. We also review the\napplication of strong lensing and microlensing to constraining the granularity\nof the lens potential, i.e. the contribution of the baryonic and dark matter\ncomponents, and the local mass distribution in the lens, i.e. the stellar mass\nfunction. Finally, we discuss the future of the field, including the new\npossibilities that will be opened by the next generation of large surveys and\nby new analysis methods now being developed." }, { "anchor": "A universal correlation between warm and hot gas in the stripped tails\n of cluster galaxies: The impact of ram pressure stripping on galaxy evolution is well known.\nRecent multi-wavelength data have revealed many examples of galaxies undergoing\nstripping, often accompanied with multi-phase tails. As energy transfer in the\nmulti-phase medium is an outstanding question in astrophysics, galaxies in\nstripping are great objects to study. Despite the recent burst of observational\nevidence, the relationship between gas in different phases in the tails is\npoorly known. Here we report a strong linear correlation between the X-ray\nsurface brightness and the H$\\alpha$ surface brightness of the diffuse gas in\nthe stripped tails at $\\sim$ 10 - 40 kpc scales, with a slope of $\\sim$ 3.5.\nThis discovery provides evidence for the mixing of the stripped interstellar\nmedium with the hot intracluster medium as the origin of the multi-phase tails.\nThe established relation in stripped tails, also in comparison with the likely\nrelated correlations in similar environments like galactic winds and X-ray cool\ncores, provides an important test for models of energy transfer in the\nmulti-phase gas. It also indicates the importance of the H$\\alpha$ data to\nstudy clumping and turbulence in the intracluster medium.", "positive": "Stellar Orbital Studies in Normal Spiral Galaxies II: Restrictions to\n Structural and Dynamical parameters on Spiral Arms: Making use of a set of detailed potential models for normal spiral galaxies,\nwe analyze the disk stellar orbital dynamics as the structural and dynamical\nparameters of the spiral arms (mass, pattern speed and pitch angle) are\ngradually modified. With this comprehensive study of ordered and chaotic\nbehavior, we constructed an assemblage of orbitally supported galactic models\nand plausible parameters for orbitally self-consistent spiral arms models. We\nfind that, to maintain orbital support for the spiral arms, the spiral arm\nmass, M$_{sp}$, must decrease with the increase of the pitch angle, $i$; if $i$\nis smaller than $\\sim10\\deg$, M$_{sp}$ can be as large as $\\sim7\\%$, $\\sim6\\%$,\n$\\sim5\\%$ of the disk mass, for Sa, Sb, and Sc galaxies, respectively. If $i$\nincreases up to $\\sim25\\deg$, the maximum M$_{sp}$ is $\\sim1\\%$ of the disk\nmass independently in this case of morphological type. For values larger than\nthese limits, spiral arms would likely act as transient features. Regarding the\nlimits posed by extreme chaotic behavior, we find a strong restriction on the\nmaximum plausible values of spiral arms parameters on disk galaxies beyond\nwhich, chaotic behavior becomes pervasive. We find that for $i$ smaller than\n$\\sim20\\deg$, $\\sim25\\deg$, $\\sim30\\deg$, for Sa, Sb, and Sc galaxies,\nrespectively, M$_{sp}$ can go up to $\\sim10\\%$, of the mass of the disk. If the\ncorresponding $i$ is around $\\sim40\\deg$, $\\sim45\\deg$, $\\sim50\\deg$, M$_{sp}$\nis $\\sim1\\%$, $\\sim2\\%$, $\\sim3\\%$ of the mass of the disk. Beyond these\nvalues, chaos dominates phase space, destroying the main periodic and the\nneighboring quasi-periodic orbits." }, { "anchor": "The catalog of nearby black hole candidates: Context. In order to study the association of the origin of ultra high energy\ncosmic rays (UHECR) with active galactic nuclei (AGN) at all levels of their\nactivity we require an unbiased sample of black holes. Aims. Here we describe\nsuch a sample, of about 6 000 black holes, within the local Universe, inside\nthe GZK (Greisen Zatsepin Kuzmin) limit, around 100 Mpc. Methods. The starting\npoint is the 2 micron all sky survey, with the next steps as: test its com-\npleteness down to low flux densities, confine it to redshifts z < 0.025, limit\nit to early Hubble type galaxies, test with B-V colors and with the FIR/Radio\nratio the possible separation in classes of sources for the ultra high energy\ncosmic rays, use the spheroidal stellar component - black hole mass\nrelationship to derive black hole masses, and test them with known black hole\nmasses. Results. The statistics are consistent with the mass function of black\nhole masses, with a rel- atively flat distribution to about 10^8 Msol, and\nthereafter a very steep spectrum. Our sample cuts off just below 10^7 Msol,\nindicating a gap for lower masses, below somewhere near 10^6 Msol. We construct\nthe sky distribution for all black holes above 10^7 Msol, 10^8 Msol, and 3 x\n10^8 Msol, and also show the sky distribution for the five redshift ranges 0.0\n- 0.005, 0.005 - 0.0010, 0.010 - 0.015, 0.015 - 0.020, and 0.020 to 0.025.", "positive": "Constraints on the assembly history of the Milky Way's smooth, diffuse\n stellar halo from the metallicity-dependent, radially-dominated velocity\n anisotropy profiles probed with K giants and BHB stars using LAMOST,\n SDSS/SEGUE, and Gaia: We analyze the anisotropy profile of the Milky Way's smooth, diffuse stellar\nhalo using SDSS/SEGUE blue horizontal branch stars and SDSS/SEGUE and LAMOST K\ngiants. These intrinsically luminous stars allow us to probe the halo to\napproximately 100 kpc from the Galactic center. Line-of-sight velocities,\ndistances, metallicities, and proper motions are available for all stars via\nSDSS/SEGUE, LAMOST, and Gaia, and we use these data to construct a full 7D set\nconsisting of positions, space motions, and metallicity. We remove substructure\nfrom our samples using integrals of motion based on the method of Xue et al. We\nfind radially dominated kinematic profiles with nearly constant anisotropy\nwithin 20 kpc, beyond which the anisotropy profile gently declines although\nremains radially dominated to the furthest extents of our sample. Independent\nof star type or substructure removal, the anisotropy depends on metallicity,\nsuch that the orbits of the stars become less radial with decreasing\nmetallicity. For $-1.7<$ [Fe/H] $<-1$, the smooth, diffuse halo anisotropy\nprofile begins to decline at Galactocentric distances $\\sim20$ kpc, from\n$\\beta\\sim0.9$ to 0.7 for K giants and from $\\beta\\sim0.8$ to 0.1 for blue\nhorizontal branch stars. For [Fe/H] $<-1.7$, the smooth, diffuse halo\nanisotropy remains constant along all distances with $0.2<\\beta<0.7$ depending\non the metallicity range probed, although independent on star type. These\nsamples are ideal for estimating the total Galactic mass as they represent the\nvirialized stellar halo system." }, { "anchor": "Photometric candidate selection and spectroscopic confirmation of new\n PNe and SySts in the Galactic plane: About 3,500 planetary nebulae (PNe) are currently known in the Milky Way,\nwhich shows a great discrepancy with the expected number for these objects,\nregardless of the reference used, $33-59 \\times 10^{3}$. The same holds for\nsymbiotic stars (SySts) as well, since the expected number in the Galaxy\n($3-400 \\times 10^{3}$) differs considerably from the amount of known ones\n(approximately 300). Studies on PNe and SySts are of great importance because\nthey provide vital clues to the understanding of the late-stage of stellar\nevolution for low-to-intermediate mass stars. In addition, these classes of\nobjects play a large role in the chemical evolution of the Galaxy through the\nejection of their material to the interstellar medium (ISM), enriching it with\nthe various chemical elements produced throughout their evolution. This project\naims to contribute to the detection of new PNe and SySts in the Galaxy, thus\ndecreasing the discrepancy between the observed and theoretical populations.\nUsing simultaneously the third data release from the optical survey VPHAS+ (The\nVST Photometric H$\\alpha$ Survey of the Southern Galactic Plane and Bulge),\nwhich maps the southern hemisphere of the Galaxy's plane with the $r$, $i$, and\nH{$\\alpha$} filters, and the IR colors of the catalog AllWISE (Wide-field\nInfrared Survey Explorer + The Two Micron All Sky Survey), we end up with a\nnumber of PN and SySt candidates. Subsequently, we confirm the nature of these\nobjects through spectroscopic observations at the SOAR telescope (Southern\nAstrophysical Research Telescope). So far, we have selected PN candidates and\nperformed the spectroscopic follow-up of 8 of them. In this presentation we\nshow the project's preliminary results, which consist of the discovery of at\nleast one new planetary nebula, and other emission-line sources still to be\nconfirmed either as PN or SySt.", "positive": "Metal and dust evolution in ALMA REBELS galaxies: insights for future\n JWST observations: ALMA observations revealed the presence of significant amounts of dust in the\nfirst Gyr of Cosmic time. However, the metal and dust buildup picture remains\nvery uncertain due to the lack of constraints on metallicity. JWST has started\nto reveal the metal content of high-redshift targets, which may lead to firmer\nconstraints on high-redshift dusty galaxies evolution. In this work, we use\ndetailed chemical and dust evolution models to explore the evolution of\ngalaxies within the ALMA REBELS survey, testing different metallicity scenarios\nthat could be inferred from JWST observations. In the models, we track the\nbuildup of stellar mass by using non-parametric SFHs for REBELS galaxies.\nDifferent scenarios for metal and dust evolution are simulated by allowing\ndifferent prescriptions for gas flows and dust processes. The model outputs are\ncompared with measured dust scaling relations, by employing\nmetallicity-dependent calibrations for the gas mass based on the [CII]158micron\nline. Independently of the galaxies metal content, we found no need for extreme\ndust prescriptions to explain the dust masses revealed by ALMA. However,\ndifferent levels of metal enrichment will lead to different dominant dust\nproduction mechanisms, with stardust production dominant over other ISM dust\nprocesses only in the metal-poor case. This points out how metallicity\nmeasurements from JWST will significantly improve our understanding of the dust\nbuildup in high-redshift galaxies. We also show that models struggle to\nreproduce observables such as dust-to-gas and dust-to-stellar ratios\nsimultaneously, possibly indicating an overestimation of the gas mass through\ncurrent calibrations, especially at high metallicities." }, { "anchor": "Identifying the first generation of radio powerful AGN in the Universe\n with the SKA: One of the most challenging and exciting subjects in modern astrophysics is\nthat of galaxy formation at the epoch of reionisation. The SKA, with its\nrevolutionary capabilities in terms of frequency range, resolution and\nsensitivity, will allow to explore the first Gyr of structure formation in the\nUniverse, in particular, with the detection and study of the earliest\nmanifestations of the AGN phenomenon. The tens of QSOs that are currently known\nout to the highest redshifts (z~7), many of them exhibiting powerful radio\nemission, imply that super-massive black holes can be grown on a very short\ntimescale and support the existence of very high redshift (z > 7) radio loud\nsources - sources that have so far escaped detection. Not only would such\ndetections be paramount to the understanding of the earliest stages of galaxy\nevolution, they are necessary for the direct study of neutral hydrogen in the\nEpoch of Reionisation, through observations of the HI 21cm forest against such\nbackground sources. In order to understand how SKA and SKA1 observations can be\noptimised to reveal these earliest AGN, we have examined the effect of a hot\nCMB on the emission of powerful and young radio galaxies. By looking at the\nSKA1 capabilities, in particular in terms of wavelength coverage and\nresolution, we determine how the effects of \"CMB-muting\" of a radio loud source\ncan be observationally minimised and how to identify the best highest-redshift\nradio candidates. Considering different predictions for the space density of\nradio loud AGN at such redshifts, we identify the survey characteristics\nnecessary to optimize the detection and identification of the very first\ngeneration of radio loud AGN in the Universe.", "positive": "DAWIS, a Detection Algorithm with Wavelets for Intracluster light\n Studies: Large amounts of deep optical images will be available in the near future,\nallowing statistically significant studies of low surface brightness structures\nsuch as intracluster light (ICL) in galaxy clusters. The detection of these\nstructures requires efficient algorithms dedicated to this task, where\ntraditional methods suffer difficulties. We present our new Detection Algorithm\nwith Wavelets for Intracluster light Studies (DAWIS), developed and optimised\nfor the detection of low surface brightness sources in images, in particular\n(but not limited to) ICL. DAWIS follows a multiresolution vision based on\nwavelet representation to detect sources, embedded in an iterative procedure\ncalled synthesis-by-analysis approach to restore the complete unmasked light\ndistribution of these sources with very good quality. The algorithm is built so\nsources can be classified based on criteria depending on the analysis goal; we\ndisplay in this work the case of ICL detection and the measurement of ICL\nfractions. We test the efficiency of DAWIS on 270 mock images of galaxy\nclusters with various ICL profiles and compare its efficiency to more\ntraditional ICL detection methods such as the surface brightness threshold\nmethod. We also run DAWIS on a real galaxy cluster image, and compare the\noutput to results obtained with previous multiscale analysis algorithms. We\nfind in simulations that in average DAWIS is able to disentangle galaxy light\nfrom ICL more efficiently, and to detect a greater quantity of ICL flux due to\nthe way it handles sky background noise. We also show that the ICL fraction, a\nmetric used on a regular basis to characterise ICL, is subject to several\nmeasurement biases both on galaxies and ICL fluxes. In the real galaxy cluster\nimage, DAWIS detects a faint and extended source with an absolute magnitude two\norders brighter than previous multiscale methods." }, { "anchor": "The Carriers of the \"Unidentified\" Infrared Emission Features: Clues\n from Polycyclic Aromatic Hydrocarbons with Aliphatic Sidegroups: The \"unidentified\" infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6,\nand 11.3 $\\mu$m are ubiquitously seen in various astrophysical regions. The UIE\nfeatures are characteristic of the stretching and bending vibrations of\naromatic hydrocarbons. The 3.3 $\\mu$m feature resulting from aromatic C--H\nstretches is often accompanied by a weaker feature at 3.4 $\\mu$m often\nattributed to aliphatic C--H stretches. The ratio of the observed intensity of\nthe 3.3 $\\mu$m aromatic C--H feature ($I_{3.3}$) to that of the 3.4 $\\mu$m\naliphatic C--H feature ($I_{3.4}$) allows one to estimate the aliphatic\nfraction (i.e. $N_{\\rm C,aliph}/N_{\\rm C,arom}$, the number of C atoms in\naliphatic units to that in aromatic rings) of the UIE carriers, provided the\nintrinsic oscillator strengths of the 3.3 $\\mu$m aromatic C--H stretch\n($A_{3.3}$) and the 3.4 $\\mu$m aliphatic C--H stretch ($A_{3.4}$) are known.\n In this article we summarize the computational results on $A_{3.3}$ and\n$A_{3.4}$ and their implications for the aromaticity and aliphaticity of the\nUIE carriers. We use density functional theory and second-order perturbation\ntheory to derive $A_{3.3}$ and $A_{3.4}$ from the infrared vibrational spectra\nof seven PAHs with various aliphatic substituents (e.g., methyl-, dimethyl-,\nethyl-, propyl-, butyl-PAHs, and PAHs with unsaturated alkyl-chains). The mean\nband strengths of the aromatic ($A_{3.3}$) and aliphatic ($A_{3.4}$) C--H\nstretches are derived and then employed to estimate the aliphatic fraction of\nthe UIE carriers by comparing $A_{3.4}$/$A_{3.3}$ with $I_{3.4}$/$I_{3.3}$. We\nconclude that the UIE emitters are predominantly aromatic, as revealed by the\nobservationally-derived ratio <$I_{3.4}$/$I_{3.3}$> ~ 0.12 and the\ncomputationally-derived ratio <$A_{3.4}$/$A_{3.3}$> ~ 1.76 which suggest an\nupper limit of $N_{\\rm C,aliph}/N_{\\rm C,arom}$ ~ 0.02 for the aliphatic\nfraction of the UIE carriers.", "positive": "Planes of satellite galaxies: when exceptions are the rule: The detection of planar structures within the satellite systems of both the\nMilky Way (MW) and Andromeda (M31) has been reported as being in stark\ncontradiction to the predictions of the standard cosmological model\n($\\Lambda$CDM). Given the ambiguity in defining a planar configuration, it is\nunclear how to interpret the low incidence of the MW and M31 planes in\n$\\Lambda$CDM. We investigate the prevalence of satellite planes around galactic\nmass haloes identified in high resolution cosmological simulations. We find\nthat planar structures are very common, and that ~10% of $\\Lambda$CDM haloes\nhave even more prominent planes than those present in the Local Group. While\nubiquitous, the planes of satellite galaxies show a large diversity in their\nproperties. This precludes using one or two systems as small scale probes of\ncosmology, since a large sample of satellite systems is needed to obtain a good\nmeasure of the object-to-object variation. This very diversity has been\nmisinterpreted as a discrepancy between the satellite planes observed in the\nLocal Group and $\\Lambda$CDM predictions. In fact, ~10% of $\\Lambda$CDM\ngalactic haloes have planes of satellites that are as infrequent as the MW and\nM31 planes. The look-elsewhere effect plays an important role in assessing the\ndetection significance of satellite planes and accounting for it leads to\noverestimating the significance level by a factor of 30 and 100 for the MW and\nM31 systems, respectively." }, { "anchor": "Radio AGN in spiral galaxies: Radio AGN in the nearby Universe are more likely to be found in galaxies with\nearly-type morphology, the detection rate in spiral or late-type galaxies\n(LTGs) being around an order of magnitude lower. We combine the mJy Imaging\nVLBA Exploration at 20cm (mJIVE-20) survey with the Sloan Digital Sky Survey\n(SDSS), to study the relatively rare population of AGN in LTGs that have\nnuclear radio luminosities similar to that in their early-type counterparts.\nThe LTG AGN population is preferentially hosted by galaxies that have high\nstellar masses (M* > 10^10.8 MSun), red colours and low star-formation rates,\nwith little dependence on the detailed morphology or local environment of the\nhost LTG. The merger fraction in the LTG AGN is around 4 times higher than that\nin the general LTG population, indicating that merging is an important trigger\nfor radio AGN in these systems. The red colours of our systems extend recent\nwork which indicates that merger-triggered AGN in the nearby Universe appear\nafter the peak of the associated starburst, implying that they do not strongly\nregulate star formation. Finally, we find that in systems where parsec-scale\njets are clearly observed in our VLBI images, the jets are perpendicular to the\nmajor axis of the galaxy, indicating alignment between the accretion disc and\nthe host galaxy stellar disc.", "positive": "Spectral nuclear properties of NLS1 galaxies: It is not yet well known whether narrow line Seyfert 1 (NLS1) galaxies follow\nthe $M_{BH} - \\sigma_{\\star}$ relation found for normal galaxies. Emission\nlines, such as [SII] or [OIII]$\\lambda$5007, have been used as a surrogate of\nthe stellar velocity dispersion and various results have been obtained. On the\nother hand, some active galactic nuclei (AGNs) have shown Balmer emission with\nan additional intermediate component (IC) besides the well-known narrow and\nbroad lines. In order to re-examine the location of NLS1 in the $M_{BH} -\n\\sigma_{\\star}$ relation, we test some emission lines, such as the narrow\ncomponent (NC) of H$\\alpha$ and the forbidden [NII]$\\lambda \\lambda$6548,6584\nand [SII]$\\lambda \\lambda$6716,6731 lines, as replacements for\n$\\sigma_{\\star}$. On the other hand, we study the properties of the IC of\nH$\\alpha$ found in 14 galaxies of the sample to find a link between this\ncomponent, the central engine, and the remaining lines. We also compare the\nemission among the broad component (BC) of H$\\alpha$ and those emitted at the\nnarrow line region (NLR). We have obtained and studied medium-resolution\nspectra (170 km s$^{-1}$ FWHM at H$\\alpha$) of 36 NLS1 galaxies in the optical\nrange $\\sim$5800 - 6800\\AA. We found that, in general, most of the galaxies lie\nbelow the $M_{BH} - \\sigma_{\\star}$ relation when the NC of H$\\alpha$, [SII],\nand [NII] lines are used as a surrogate of $\\sigma_{\\star}$. Besides this, we\nfound that 13 galaxies show an IC, most of which are in the velocity range\n$\\sim$ 700 $-$ 1500 km s$^{- 1}$. This is same range as in AGN types and is\nwell correlated with the FWHM of BC and, therefore, with the BH mass. On the\nother hand, we found that there is a correlation between the luminosity of the\nBC of H$\\alpha$ and NC, IC, [NII]$\\lambda$6584, and [SII] lines." }, { "anchor": "The Redshift and Metallicity of the Host Galaxy of Dark GRB 080325 at\n z=1.78: We present near-infrared spectroscopy of the host galaxy of dark GRB 080325\nusing Subaru/MOIRCS. The obtained spectrum provides a clear detection of\nH$\\alpha$ emission and marginal [NII]$\\lambda$6584. The host is a massive\n(M$_{*}\\sim10^{11}$M$_{\\odot}$), dusty ($A_{V}\\sim 1.2$) star-forming galaxy at\nz=1.78. The star formation rate calculated from the H$\\alpha$ luminosity\n(35.6-47.0 M$_{\\odot}$ yr$^{-1}$) is typical among GRB host galaxies (and\nstar-forming galaxies generally) at z $>$1; however, the specific star\nformation rate is lower than normal star-forming galaxies at redshift $\\sim$\n1.6, in contrast to the high specific star formation rates measured for many of\nother GRB hosts. The metallicity of the host is estimated to be\n12+log(O/H)$_{\\rm KK04}$$=$8.88. We emphasize that this is one of the most\nmassive distant host galaxies for which metallcity is measured with\nemission-line diagnostics. The metallicity is fairly high among GRB hosts.\nHowever, this is still lower than the metallicity of normal star-forming\ngalaxies of the same mass at z$\\sim$1.6. The metallicity offset from normal\nstar-forming galaxies is close to a typical value of other GRB hosts and\nindicates that GRB host galaxies are uniformly biased toward low metalicity\nover a wide range of redshift and stellar mass. The low-metallicity nature of\nthe GRB 080325 host is likely not attributable to the fundamental metallicity\nrelation of star-forming galaxies beacuse it is a metal-poor outlier from the\nrelation and has a low sSFR. Thus we conclude that metallicity is important to\nthe mechanism that produced this GRB.", "positive": "Average Inhomogeneities in Milky Way SNII and The PAMELA Anomaly: A model is presented to estimate the fraction of Supernova Type-II events\n(SNII) occurring inside vs. outside a spiral arm for a given star formation\nepisode. The probability distribution function (PDF) for this fraction is given\nfor use in models similar to those of Shaviv et al. [13][11]. The calculated\nPDF for the SNII fraction, SNII_{in/total}, defined as the number of SNII\ninside a spiral arm divided by the total number of SNII from a star formation\nevent, provides a constraint on the magnitude of supernova remnant (SNR)\nconcentrations used in cosmic ray propagation models attempting to explain the\nPAMELA anomaly. Despite the concentration of star formation within spiral arms,\nthis model predicts the majority of SNII events actually occur in inter-arm\nregions and calls into question the SNR concentration assumption of Shaviv et\nal." }, { "anchor": "Impact of star formation history on the measurement of star formation\n rates: Context. Measuring star formation across the Universe is key to constrain\nmodels of galaxy formation and evolution. Yet, determining the SFR (star\nformation rate) of galaxies remains a challenge. Aims. In this paper we\ninvestigate in isolation the impact of a variable star formation history on the\nmeasurement of the SFR. Methods. We combine 23 state-of-the-art hydrodynamical\nsimulations of 150$ kms$^{-1}$ for several galaxies\nif the separation between the galaxies $<$ 100 kpc. This, we suggest, indicates\na change in the orbital angular momentum of the torqued galaxies. A major\ndifference between the torque origin suggested here and the existing model of\ngas accretion/galaxy collision, generally used to explain the above two\nphenomena, is that the torque acts on the matter of the same galaxy whereas in\nthe latter case gas, with different properties, is brought in from outside. An\nimportant implication of our study is that mutual gravity torques acting on the\ngalaxy can explain the formation of warps, polar ring galaxies and lenticular\ngalaxies. We conclude that mutual gravity torques play an important role in the\ndynamical evolution of galaxies and that they naturally explain several galaxy\nobservables." }, { "anchor": "Globular Cluster Formation from Colliding Substructure: We investigate a scenario where the formation of Globular Clusters (GCs) is\ntriggered by high-speed collisions between infalling atomic-cooling subhalos\nduring the assembly of the main galaxy host, a special dynamical mode of star\nformation that operates at high gas pressures and is intimately tied to LCDM\nhierarchical galaxy assembly. The proposed mechanism would give origin to\n\"naked\" globulars, as colliding dark matter subhalos and their stars will\nsimply pass through one another while the warm gas within them clashes at\nhighly supersonic speed and decouples from the collisionless component, in a\nprocess reminiscent of the Bullet galaxy cluster. We find that the resulting\nshock-compressed layer cools on a timescale that is typically shorter than the\ncrossing time, first by atomic line emission and then via fine-structure\nmetal-line emission, and is subject to gravitational instability and\nfragmentation. Through a combination of kinetic theory approximation and\nhigh-resolution $N$-body simulations, we show that this model may produce: (a)\na GC number-halo mass relation that is linear down to dwarf galaxy scales and\nagrees with the trend observed over five orders of magnitude in galaxy mass;\n(b) a population of old globulars with a median age of 12 Gyr and an age spread\nsimilar to that observed; (c) a spatial distribution that is biased relative to\nthe overall mass profile of the host; and (d) a bimodal metallicity\ndistribution with a spread similar to that observed in massive galaxies.", "positive": "High CO depletion in southern infrared-dark clouds: Infrared-dark high-mass clumps are among the most promising objects to study\nthe initial conditions of the formation process of high-mass stars and rich\nstellar clusters. In this work, we have observed the (3-2) rotational\ntransition of C18O with the APEX telescope, and the (1,1) and (2,2) inversion\ntransitions of NH3 with the Australia Telescope Compact Array in 21\ninfrared-dark clouds already mapped in the 1.2 mm continuum, with the aim of\nmeasuring basic chemical and physical parameters such as the CO depletion\nfactor (fD), the gas kinetic temperature and the gas mass. In particular, the\nC18O (3-2) line allows us to derive fD in gas at densities higher than that\ntraced by the (1-0) and (2-1) lines, typically used in previous works. We have\ndetected NH3 and C18O in all targets. The clumps possess mass, H2 column and\nsurface densities consistent with being potentially the birthplace of high-mass\nstars. We have measured fD in between 5 and 78, with a mean value of 32 and a\nmedian of 29. These values are, to our knowledge, larger than the typical CO\ndepletion factors measured towards infrared-dark clouds and high-mass dense\ncores, and are comparable to or larger than the values measured in low-mass\npre-stellar cores close to the onset of the gravitational collapse. This result\nsuggests that the earliest phases of the high-mass star and stellar cluster\nformation process are characterised by fD larger than in low-mass pre-stellar\ncores. Thirteen out of 21 clumps are undetected in the 24 {\\mu}m Spitzer\nimages, and have slightly lower kinetic temperatures, masses and H2 column\ndensities with respect to the eight Spitzer-bright sources. This could indicate\nthat the Spitzer-dark clumps are either less evolved or are going to form less\nmassive objects." }, { "anchor": "Spectroscopy of BL Lac objects of extraordinary luminosity: Aims. We aim to determine the redshift (or stringent lower limits) of a\nnumber of bright BL Lacs objects. Methods. We secured medium resolution optical\nand near-infrared spectra of 4 bright BL Lac objects of unknown redshift using\nthe spectrograph X-Shooter at the ESO-VLT. Results. In spite of the high\nquality of the spectra and the extended spectral range of the observations we\nhave not detected intrisic spectral features for these sources. However we are\nable to provide strigent lower limits to their redshift. In particular, for the\ntwo TeV sources PG 1553+113 and H 1722+119 we infer z > 0.30 and z > 0.35\nrespectively. We also detect an intervening Ca II absorption doublet in the\nspectrum of MH 2136-428 that is ascribed to the the halo of a nearby giant\nelliptical galaxy at \\sim 100 kpc of projected distance. Conclusions. Under the\nhypothesis that all BL Lacs are hosted by luminous bulge dominated galaxies,\nthe present state of art spectroscopic observations of bright BL Lacs indicate\nthat these objects are likely sources with extremely beamed nuclear emission .\nWe present simulations to show under which circustances it will be possible to\nprobe this hypothesis from the detection of very weak absorptions using the\nnext generation of extremely large optical telescopes.", "positive": "Gravitational anti-screening and binary galaxies: Previously, in Penner (2016a, 2016b), a theory of gravitational\nanti-screening was shown to lead naturally to the Baryonic Tully-Fisher\nRelationship. In addition, it was shown to agree with the observed rotational\ncurve of the Galaxy, the observed features in the rotational curves of other\nspiral galaxies, with observations of the Coma cluster, and with a\ngeometrically flat universe. In this paper the theory will now be applied to\nbinary galaxies. It is shown that there is a relationship between the\nline-of-sight velocity difference of the pair and the individual rotational\nvelocities of the galaxies. The resulting probability function for beta,\ndefined as the ratio of the line-of-sight velocity difference to the rotational\nvelocity of the larger galaxy of the pair, is in excellent agreement with the\nobservations taken by multiple researchers for the case of the binaries being\non radial orbits." }, { "anchor": "The Supershell-Molecular Cloud Connection: Large-Scale Stellar Feedback\n and the Formation of the Molecular ISM: The accumulation, compression and cooling of the ambient interstellar medium\n(ISM) in large-scale flows powered by OB cluster feedback can drive the\nproduction of dense molecular clouds. We review the current state of the field,\nwith a strong focus on the explicit modelling and observation of the neutral\ninterstellar medium. Magneto-hydrodynamic simulations of colliding ISM flows\nprovide a strong theoretical framework in which to view feedback-driven cloud\nformation, as do models of the gravitational fragmentation of expanding shells.\nRapid theoretical developments are accompanied by growing body of observational\nwork that provides good evidence for the formation of molecular gas via stellar\nfeedback - both in the Milky Way and the Large Magellanic Cloud. The importance\nof stellar feedback compared to other major astrophysical drivers of dense gas\nformation remains to be investigated further, and will be an important target\nfor future work.", "positive": "The ortho-to-para ratio of H$_2$Cl$^+$: Quasi-classical trajectory\n calculations and new simulations in light of new observations: Multi-hydrogenated species with proper symmetry properties can present\ndifferent spin configurations, and thus exist under different spin symmetry\nforms, labeled as para and ortho for two-hydrogen molecules. We investigated\nhere the ortho-to-para ratio (OPR) of H$_2$Cl$^+$ in the light of new\nobservations performed in the z=0.89 absorber toward the lensed quasar PKS\n1830-211 with the Atacama Large Millimeter/submillimeter Array (ALMA). Two\nindependent lines of sight were observed, to the southwest (SW) and northeast\n(NE) images of the quasar, with OPR values found to be $3.15 \\pm 0.13$ and $3.1\n\\pm 0.5$ in each region, respectively, in agreement with a spin statistical\nweight of 3:1. An OPR of 3:1 for a molecule containing two identical hydrogen\nnuclei can refer to either a statistical result or a high-temperature limit\ndepending on the reaction mechanism leading to its formation. It is thus\ncrucial to identify rigorously how OPRs are produced in order to constrain the\ninformation that these probes can provide. To understand the production of the\nH$_2$Cl$^+$ OPR, we undertook a careful theoretical study of the reaction\nmechanisms involved with the aid of quasi-classical trajectory calculations on\na new global potential energy surface fit to a large number of high-level ab\ninitio data. Our study shows that the major formation reaction for H$_2$Cl$^+$\nproduces this ion via a hydrogen abstraction rather than a scrambling\nmechanism. Such a mechanism leads to a 3:1 OPR, which is not changed by\ndestruction and possible thermalization reactions for H$_2$Cl$^+$ and is thus\nlikely to be the cause of observed 3:1 OPR ratios, contrary to the normal\nassumption of scrambling." }, { "anchor": "The contribution of N-rich stars to the Galactic stellar halo using\n APOGEE red giants: The contribution of dissolved globular clusters (GCs) to the stellar content\nof the Galactic halo is a key constraint on models for GC formation and\ndestruction, and the mass assembly history of the Milky Way. Earlier results\nfrom APOGEE pointed to a large contribution of destroyed GCs to the stellar\ncontent of the inner halo, by as much as 25$\\%$, which is an order of magnitude\nlarger than previous estimates for more distant regions of the halo. We set out\nto measure the ratio between N-rich and normal halo field stars, as a function\nof distance, by performing density modelling of halo field populations in\nAPOGEE DR16. Our results show that at 1.5 kpc from the Galactic Centre, N-rich\nstars contribute a much higher 16.8$^{+10.0}_{-7.0}$$\\%$ fraction to the total\nstellar halo mass budget than the 2.7$^{+1.0}_{-0.8}$$\\%$ ratio contributed at\n10 kpc. Under the assumption that N-rich stars are former GC members that now\nreside in the stellar halo field, and assuming the ratio between first-and\nsecond-population GC stars being 1:2, we estimate a total contribution from\ndisrupted GC stars of the order of 27.5$^{+15.4}_{-11.5}$$\\%$ at r = 1.5 kpc\nand 4.2$^{+1.5}_{-1.3}$$\\%$ at r = 10 kpc. Furthermore, since our methodology\nrequires fitting a density model to the stellar halo, we integrate such density\nwithin a spherical shell from 1.5-15 kpc in radius, and find a total stellar\nmass arising from dissolved and/or evaporated GCs of $M_{\\mathrm{GC,total}}$ =\n9.6$^{+4.0}_{-2.6}$ $\\times$ 10$^{7}$ M$\\odot$.", "positive": "NGC 362: another globular cluster with a split red giant branch: We obtained FLAMES GIRAFFE+UVES spectra for both first and second-generation\nred giant branch (RGB) stars in the globular cluster (GC) NGC 362 and used them\nto derive abundances of 21 atomic species for a sample of 92 stars. The\nsurveyed elements include proton-capture (O, Na, Mg, Al, Si), alpha-capture\n(Ca, Ti), Fe-peak (Sc, V, Mn, Co, Ni, Cu), and neutron-capture elements (Y, Zr,\nBa, La, Ce, Nd, Eu, Dy). The analysis is fully consistent with that presented\nfor twenty GCs in previous papers of this series. Stars in NGC 362 seem to be\nclustered into two discrete groups along the Na-O anti-correlation, with a gap\nat [O/Na] 0 dex. Na-rich, second generation stars show a trend to be more\ncentrally concentrated, although the level of confidence is not very high. When\ncompared to the classical second-parameter twin NGC 288, with similar\nmetallicity, but different horizontal branch type and much lower total mass,\nthe proton-capture processing in stars of NGC 362 seems to be more extreme,\nconfirming previous analysis. We discovered the presence of a secondary RGB\nsequence, redder than the bulk of the RGB: a preliminary estimate shows that\nthis sequence comprises about 6% of RGB stars. Our spectroscopic data and\nliterature photometry indicate that this sequence is populated almost\nexclusively by giants rich in Ba, and probably rich in all s-process elements,\nas found in other clusters. In this regards, NGC 362 joins previously studied\nGCs like NGC 1851, NGC 6656 (M 22), and NGC 7089 (M 2)." }, { "anchor": "EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of\n Extremely-Metal Poor Galaxies: We present demography of the dynamics and gas-mass fraction of 33 extremely\nmetal-poor galaxies (EMPGs) with metallicities of $0.015-0.195~Z_\\odot$ and low\nstellar masses of $10^4-10^8~M_\\odot$ in the local universe. We conduct deep\noptical integral-field spectroscopy (IFS) for the low-mass EMPGs with the\nmedium high resolution ($R=7500$) grism of the 8m-Subaru FOCAS IFU instrument\nby the EMPRESS 3D survey, and investigate H$\\alpha$ emission of the EMPGs.\nExploiting the resolution high enough for the low-mass galaxies, we derive gas\ndynamics with the H$\\alpha$ lines by the fitting of 3-dimensional disk models.\nWe obtain an average maximum rotation velocity ($v_\\mathrm{rot}$) of\n$15\\pm3~\\mathrm{km~s^{-1}}$ and an average intrinsic velocity dispersion\n($\\sigma_0$) of $27\\pm10~\\mathrm{km~s^{-1}}$ for 15 spatially resolved EMPGs\nout of the 33 EMPGs, and find that all of the 15 EMPGs have\n$v_\\mathrm{rot}/\\sigma_0<1$ suggesting dispersion dominated systems. There is a\nclear decreasing trend of $v_\\mathrm{rot}/\\sigma_0$ with the decreasing stellar\nmass and metallicity. We derive the gas mass fraction ($f_\\mathrm{gas}$) for\nall of the 33 EMPGs, and find no clear dependence on stellar mass and\nmetallicity. These $v_\\mathrm{rot}/\\sigma_0$ and $f_\\mathrm{gas}$ trends should\nbe compared with young high-$z$ galaxies observed by the forthcoming JWST IFS\nprograms to understand the physical origins of the EMPGs in the local universe.", "positive": "Compact Radio Sources within 30\" of Sgr A*: Proper Motions, Stellar\n Winds and the Accretion Rate onto Sgr A*: Recent broad-band 34 and 44 GHz radio continuum observations of the Galactic\ncenter have revealed 41 massive stars identified with near-IR counterparts, as\nwell as 44 proplyd candidates within 30\" of Sgr A*. Radio observations obtained\nin 2011 and 2014 have been used to derive proper motions of eight young stars\nnear Sgr A*. The accuracy of proper motion estimates based on near-IR\nobservations by Lu et al. and Paumard et al. have been investigated by using\ntheir proper motions to predict the 2014 epoch positions of near-IR stars and\ncomparing the predicted positions with those of radio counterparts in the 2014\nradio observations. Predicted positions from Lu et al. show an rms scatter of 6\nmas relative to the radio positions, while those from Paumard et al. show rms\nresiduals of 20 mas, which is mainly due to uncertainties in the IR-based\nproper motions. Under the assumption of homogeneous ionized winds, we also\ndetermine the mass-loss rates of 11 radio stars, finding rates that are on\naverage $\\sim$2 times smaller than those determined from model atmosphere\ncalculations and near-IR data. Clumpiness of ionized winds would reduce the\nmass loss rate of WR and O stars by additional factors of 3 and 10,\nrespectively. One important implication of this is a reduction in the expected\nmass accretion rate onto Sgr A* from stellar winds by nearly an order of\nmagnitude to a value of few$\\times10^{-7}$ \\msol\\ yr$^{-1}$. Finally, we\npresent the positions of 318 compact 34.5 GHz radio sources within 30\\arcs\\ of\nSgr A*. At least 45 of these have stellar counterparts in the near-IR $K_s$\n(2.18 $\\mu$m) and $L'$ (3.8$\\mu$m) bands." }, { "anchor": "What produces the far-infrared/submm emission in the most luminous QSOs?: The AGN. I examine the average spectral energy distributions (SEDs) of two\nsamples of the most powerful, unobscured QSOs at 20$ in NSCs,\nincluding those with very large initial separations (up to 1~pc). The merger\nrate density (MRD) peaks at $z\\sim 5-7$ with $\\sim 0.4-10\\ \\rm yr^{-1}\\ \\rm\nGpc^{-3}$, leading to a promising detection rate $\\sim 170-2700\\ \\rm yr^{-1}$\nfor 3rd-generation GW detectors that can reach $z\\sim 10$. Low-mass ($\\lesssim\n10^{6}\\ \\rm M_{\\odot}$) NSCs formed at high redshifts ($z\\gtrsim 4.5$) host\nmost ($\\gtrsim 90\\%$) of our mergers, which mainly consist of black holes (BHs)\nwith masses $\\sim 40-85\\ \\rm M_{\\odot}$, similar to the most massive BHs found\nin LIGO events. Particularly, our model can produce events like GW190521\ninvolving BHs in the standard mass gap for pulsational pair-instability\nsupernovae with a MRD $\\sim 0.01-0.09\\ \\rm yr^{-1}\\ Gpc^{-3}$ at $z\\sim 1$,\nconsistent with that inferred by LIGO." }, { "anchor": "A southern-sky total intensity source catalogue at 2.3 GHz from S-band\n Polarisation All-Sky Survey data: The S-band Polarisation All-Sky Survey (S-PASS) has observed the entire\nsouthern sky using the 64-metre Parkes radio telescope at 2.3GHz with an\neffective bandwidth of 184MHz. The surveyed sky area covers all declinations\n$\\delta\\leq 0^\\circ$. To analyse compact sources the survey data have been\nre-processed to produce a set of 107 Stokes $I$ maps with 10.75arcmin\nresolution and the large scale emission contribution filtered out. In this\npaper we use these Stokes $I$ images to create a total intensity southern-sky\nextragalactic source catalogue at 2.3GHz. The source catalogue contains 23,389\nsources and covers a sky area of 16,600deg$^2$, excluding the Galactic plane\nfor latitudes $|b|<10^\\circ$. Approximately 8% of catalogued sources are\nresolved. S-PASS source positions are typically accurate to within 35arcsec. At\na flux density of 225mJy the S-PASS source catalogue is more than 95% complete,\nand $\\sim$94% of S-PASS sources brighter than 500mJy beam$^{-1}$ have a\ncounterpart at lower frequencies.", "positive": "Titans of the Early Universe: The Prato Statement on the Origin of the\n First Supermassive Black Holes: In recent years, the discovery of massive quasars at z~7 has provided a\nstriking challenge to our understanding of the origin and growth of\nsupermassive black holes in the early Universe. Mounting observational and\ntheoretical evidence indicates the viability of massive seeds, formed by the\ncollapse of supermassive stars, as a progenitor model for such early, massive\naccreting black holes. Although considerable progress has been made in our\ntheoretical understanding, many questions remain regarding how (and how often)\nsuch objects may form, how they live and die, and how next generation\nobservatories may yield new insight into the origin of these primordial titans.\nThis review focusses on our present understanding of this remarkable formation\nscenario, based on discussions held at the Monash Prato Centre from November\n20--24, 2017, during the workshop \"Titans of the Early Universe: The Origin of\nthe First Supermassive Black Holes.\"" }, { "anchor": "Doubly imaged quasar SDSS J1515+1511: time delay and lensing galaxies: We analyse new optical observations of the gravitational lens system SDSS\nJ1515+1511. These include a 2.6-year photometric monitoring with the Liverpool\nTelescope (LT) in the $r$ band, as well as a spectroscopic follow-up with the\nLT and the Gran Telescopio Canarias (GTC). Our $r$-band LT light curves cover a\nquiescent microlensing period of the doubly imaged quasar at $z_{\\rm s}$ =\n2.049, which permits us to robustly estimate the time delay between the two\nimages A and B: 211 $\\pm$ 5 days (1$\\sigma$ confidence interval; A is leading).\nUnfortunately, the main lensing galaxy (G1) is so faint and close to the bright\nquasar that it is not feasible to accurately extract its spectrum through the\nGTC data. However, assuming the putative redshift $z_{\\rm G1}$ = 0.742, the GTC\nand LT spectra of the distant quasar are used to discuss the macrolens\nmagnification, and the extinction and microlensing effects in G1. The new\nconstraints on the time delay and macrolens magnification ratio essentially do\nnot change previous findings on the mass scale of G1 and external shear, while\nthe redshift of the lensing mass is found to be consistent with the assumed\nvalue of $z_{\\rm G1}$. This is a clear evidence that G1 is indeed located at\n$z_{\\rm G1}$ = 0.742. From the GTC data we also obtain the redshift of two\nadditional objects (the secondary galaxy G2 and a new absorption system) and\ndiscuss their possible role in the lens scenario.", "positive": "Characterization of dense Planck clumps observed with Herschel and\n SCUBA-2: We aim to characterize a diverse selection of dense, potentially star-forming\ncores, clumps, and clouds within the Milky Way in terms of their dust emission\nand SF activity. We studied 53 fields that have been observed in the JCMT\nSCUBA-2 continuum survey SCOPE and have been mapped with Herschel. We estimated\ndust properties by fitting Herschel observations with modified blackbody\nfunctions, studied the relationship between dust temperature and dust opacity\nspectral index $\\beta$, and estimated column densities. We extracted clumps\nfrom the SCUBA-2 850 $\\mu$m maps with the FellWalker algorithm and examined\ntheir masses and sizes. Clumps are associated with young stellar objects found\nin several catalogs. We estimated the gravitational stability of the clumps\nwith virial analysis. The clumps are categorized as unbound starless,\nprestellar, or protostellar. We find 529 dense clumps, typically with high\ncolumn densities from (0.3-4.8)$\\times 10^{22}$ cm$^{-2}$, with a mean of\n(1.5$\\pm$0.04)$\\times10^{22}$ cm$^{-2}$, low temperatures ($T\\sim $10-20 K),\nand estimated submillimeter $\\beta$ =1.7$\\pm$0.1. We detect a slight increase\nin opacity spectral index toward millimeter wavelengths. Masses of the sources\nrange from 0.04 $M_\\odot$ to 4259 $M_\\odot$. Mass, linear size, and temperature\nare correlated with distance. Furthermore, the estimated gravitational\nstability is dependent on distance, and more distant clumps appear more\nvirially bound. Finally, we present a catalog of properties of the clumps.Our\nsources present a large array of SF regions, from high-latitude, nearby diffuse\nclouds to large SF complexes near the Galactic center. Analysis of these\nregions will continue with the addition of molecular line data, which will\nallow us to study the densest regions of the clumps in more detail." }, { "anchor": "The stellar halo of isolated central galaxies in the Hyper Suprime-Cam\n imaging survey: We study the faint stellar halo of isolated central galaxies, by stacking\ngalaxy images in the HSC survey and accounting for the residual sky background\nsampled with random points. The surface brightness profiles in HSC $r$-band are\nmeasured for a wide range of galaxy stellar masses\n($9.2<\\log_{10}M_\\ast/M_\\odot<11.4$) and out to 120 kpc. Failing to account for\nthe stellar halo below the noise level of individual images will lead to\nunderestimates of the total luminosity by $\\leq 15\\%$. Splitting galaxies\naccording to the concentration parameter of their light distributions, we find\nthat the surface brightness profiles of low concentration galaxies drop faster\nbetween 20 and 100 kpc than those of high concentration galaxies. Albeit the\nlarge galaxy-to-galaxy scatter, we find a strong self-similarity of the stellar\nhalo profiles. They show unified forms once the projected distance is scaled by\nthe halo virial radius. The colour of galaxies is redder in the centre and\nbluer outside, with high concentration galaxies having redder and more\nflattened colour profiles. There are indications of a colour minimum, beyond\nwhich the colour of the outer stellar halo turns red again. This colour\nminimum, however, is very sensitive to the completeness in masking satellite\ngalaxies. We also examine the effect of the extended PSF in the measurement of\nthe stellar halo, which is particularly important for low mass or low\nconcentration galaxies. The PSF-corrected surface brightness profile can be\nmeasured down to $\\sim$31 $\\mathrm{mag}/\\mathrm{arcsec}^2$ at 3-$\\sigma$\nsignificance. PSF also slightly flattens the measured colour profiles.", "positive": "Application of Convolutional Neural Networks to Predict Magnetic Fields\n Directions in Turbulent Clouds: We adopt the deep learning method CASI-3D (Convolutional Approach to\nStructure Identification-3D) to infer the orientation of magnetic fields in\nsub-/trans- Alfvenic turbulent clouds from molecular line emission. We carry\nout magnetohydrodynamic simulations with different magnetic field strengths and\nuse these to generate synthetic observations. We apply the 3D radiation\ntransfer code RADMC-3d to model 12CO and 13CO (J = 1-0) line emission from the\nsimulated clouds and then train a CASI-3D model on these line emission data\ncubes to predict magnetic field morphology at the pixel level. The trained\nCASI-3D model is able to infer magnetic field directions with low error (<\n10deg for sub-Alfvenic samples and <30deg for trans-Alfvenic samples). We\nfurthermore test the performance of CASI-3D on a real sub-/trans- Alfvenic\nregion in Taurus. The CASI-3D prediction is consistent with the magnetic field\ndirection inferred from Planck dust polarization measurements. We use our\ndeveloped methods to produce a new magnetic field map of Taurus that has a\nthree-times higher angular resolution than the Planck map." }, { "anchor": "A fast-rotator post-starburst galaxy quenched by supermassive black-hole\n feedback at z=3: There is compelling evidence that the most massive galaxies in the Universe\nstopped forming stars due to the time-integrated feedback from their central\nsuper-massive black holes (SMBHs). However, the exact quenching mechanism is\nnot yet understood, because local massive galaxies were quenched billions of\nyears ago. We present JWST/NIRSpec integral-field spectroscopy observations of\nGS-10578, a massive, quiescent galaxy at redshift z=3.064. From the spectrum we\ninfer that the galaxy has a stellar mass of $M_*=1.6\\pm0.2 \\times 10^{11}$ MSun\nand a dynamical mass $M_{\\rm dyn}=2.0\\pm0.5 \\times 10^{11}$ MSun. Half of its\nstellar mass formed at z=3.7-4.6, and the system is now quiescent, with the\ncurrent star-formation rate SFR<9 MSun/yr. We detect ionised- and neutral-gas\noutflows traced by [OIII] emission and NaI absorption. Outflow velocities reach\n$v_{\\rm out}\\approx$1,000 km/s, comparable to the galaxy escape velocity and\ntoo high to be explained by star formation alone. GS-10578 hosts an Active\nGalactic Nucleus (AGN), evidence that these outflows are due to SMBH feedback.\nThe outflow rates are 0.14-2.9 and 30-300 MSun/yr for the ionised and neutral\nphases, respectively. The neutral outflow rate is ten times higher than the\nSFR, hence this is direct evidence for ejective SMBH feedback, with\nmass-loading capable of interrupting star formation by rapidly removing its\nfuel. Stellar kinematics show ordered rotation, with spin parameter\n$\\lambda_{Re}=0.62\\pm0.07$, meaning GS-10578 is rotation supported. This study\nshows direct evidence for ejective AGN feedback in a massive, recently quenched\ngalaxy, thus clarifying how SMBHs quench their hosts. Quenching can occur\nwithout destroying the stellar disc.", "positive": "Detection of Gravitational Redshift in Open Cluster non-degenerate stars: A key observational prediction of Einstein's Equivalence Principle is that\nlight undergoes redshift when it escapes from a gravitational field. Although\nastrophysics provides a wide variety of physical conditions in which this\nredshift should be significant, till very recently the observational evidence\nfor this gravitational effect was limited to the light emitted by the Sun and\nwhite dwarfs. \\textit{Gaia}-DR2 astrometric and kinematic data, in combination\nwith other spectroscopic observations, provides a test bench to validate such\npredictions in statistical terms. The aim of this paper is to analyze several\nthousand main-sequence and giant stars in open clusters (OCs) to measure the\ngravitational redshift effect. Observationally, a spectral shift will depend on\nthe stellar mass-to-radius ratio as expected from the theoretical estimation of\nrelativity. After the analysis, the obtained correlation coefficient between\ntheoretical predictions and observations for 28 (51) OCs is $a= 0.977 \\pm\n0.218$ ($0.899 \\pm 0.137$). The result has proven to be statistically robust\nand with little dependence on the details of the methodology or sample\nselection criteria. This study represents one of the more extensive validations\nof a fundamental prediction of gravity theories." }, { "anchor": "Collapse and Fragmentation of Molecular Cloud Cores. X. Magnetic Braking\n of Prolate and Oblate Cores: The collapse and fragmentation of initially prolate and oblate, magnetic\nmolecular clouds is calculated in three dimensions with a gravitational,\nradiative hydrodynamics code. The code includes magnetic field effects in an\napproximate manner: magnetic pressure, tension, braking, and ambipolar\ndiffusion are all modelled. The parameters varied for both the initially\nprolate and oblate clouds are the initial degree of central concentration of\nthe radial density profile, the initial angular velocity, and the efficiency of\nmagnetic braking (represented by a factor $f_{mb} = 10^{-4}$ or $10^{-3}$). The\noblate cores all collapse to form rings that might be susceptible to\nfragmentation into multiple systems. The outcome of the collapse of the prolate\ncores depends strongly on the initial density profile. Prolate cores with\ncentral densities 20 times higher than their boundary densities collapse and\nfragment into binary or quadruple systems, whereas cores with central densities\n100 times higher collapse to form single protostars embedded in bars. The\ninclusion of magnetic braking is able to stifle protostellar fragmentation in\nthe latter set of models, as when identical models were calculated without\nmagnetic braking (Boss 2002), those cores fragmented into binary protostars.\nThese models demonstrate the importance of including magnetic fields in studies\nof protostellar collapse and fragmentation, and suggest that even when magnetic\nfields are included, fragmentation into binary and multiple systems remains as\na possible outcome of protostellar collapse.", "positive": "Resolving shocks and filaments in galaxy formation simulations: effects\n on gas properties and star formation in the circumgalactic medium: There is an emerging consensus that large amounts of gas do not shock heat in\nthe circumgalactic medium (CGM) of massive galaxies, but instead pierce deep\ninto haloes from the cosmic web via filaments. To better resolve this process\nnumerically, we have developed a novel `shock refinement' scheme within the\nmoving mesh code AREPO that adaptively improves resolution around shocks\non-the-fly in galaxy formation simulations. We apply this to a massive\n$\\sim10^{12}$ M$_\\odot$ halo at $z=6$ using the successful FABLE model,\nincreasing the mass resolution by a factor of 512. With better refinement there\nare significantly more dense, metal-poor and fast-moving filaments and clumps\nflowing into the halo, leading to a more multiphase CGM. We find a $\\sim50$ per\ncent boost in cool-dense gas mass and a 25 per cent increase in inflowing mass\nflux. Better resolved accretion shocks cause turbulence to increase\ndramatically, leading to a doubling in the halo's non-thermal pressure support.\nDespite much higher thermalisation at shocks with higher resolution, increased\ncooling rates suppress the thermal energy of the halo. In contrast, the faster\nand denser filaments cause a significant jump in the bulk kinetic energy of\ncool-dense gas, while in the hot phase turbulent energy increases by up to\n$\\sim150$ per cent. Moreover, HI covering fractions within the CGM increase by\nup to 60 per cent. Consequently star formation is spread more widely and we\npredict a population of metal-poor stars forming within primordial filaments\nthat deep JWST observations may be able to probe." }, { "anchor": "PAH destruction and survival in the disks of T Tauri stars: In Spitzer observations of Tauri stars and their disks, PAH features are\ndetected in less than 10% of the objects, although the stellar photosphere is\nsufficiently hot to excite PAHs. To explain the deficiency, we discuss PAH\ndestruction by photons assuming that the star has beside its photospheric\nemission also a FUV, an EUV and an X-ray component with fractional luminosity\nof 1%, 0.1% and 0.025%, respectively. As PAH destruction process we consider\nunimolecular dissociation and present a simplified scheme to estimate the\nlocation from the star where the molecules become photo-stable. We find that\nsoft photons with energies below ~20eV dissociate PAHs only up to short\ndistances from the star (r < 1AU); whereas dissociation by hard photons (EUV\nand X-ray) is so efficient that it would destroy all PAHs (from regions in the\ndisk where they could be excited). As a possible path for PAH survival we\nsuggest turbulent motions in the disk. They can replenish PAHs or remove them\nfrom the reach of hard photons. For standard disk models, where the surface\ndensity changes like 1/r and the mid plane temperature like 1/r^{0.5}, the\ncritical vertical velocity for PAH survival is proportional to r^{-3/4} and\nequals ~5m/s at 10AU which is in the range of expected velocities in the\nsurface layer. The uncertainty in the parameters is large enough to explain\nboth detection and non-detection of PAHs. Our approximate treatment also takes\ninto account the presence of gas which, at the top of the disk, is ionized and\nat lower levels neutral.", "positive": "Dust attenuation up to z~2 in the AKARI North Ecliptic Pole Deep Field: (Abridged) We aim to study the evolution of dust attenuation in galaxies\nselected in the IR in the redshift range in which they are known to dominate\nthe star formation activity in the universe. The comparison with other\nmeasurements of dust attenuation in samples selected using different criteria\nwill give us a global picture of the attenuation at work in star-forming\ngalaxies and its evolution with redshift. Using multiple filters of IRC\ninstrument, we selected more than 4000 galaxies from their rest-frame emission\nat 8 microns, from z~0.2 to 2$. We built SEDs from the rest-frame UV to the\nfar-IR by adding data in the optical-NIR and from GALEX and Herschel surveys.\nWe fit SEDs with the physically-motivated code CIGALE. We test different\ntemplates for AGNs and recipes for dust attenuation and estimate stellar\nmasses, SFRs, amount of dust attenuation, and AGN contribution to the total IR\nluminosity. The AGN contribution to the total IR luminosity is found to be on\naverage approximately 10% with a slight increase with redshift. Dust\nattenuation in galaxies dominating the IR luminosity function is found to\nincrease from z=0 to z=1 and to remain almost constant from z=1 to z=1.5.\nConversely, when galaxies are selected at a fixed IR luminosity, their dust\nattenuation slightly decreases as redshift increases but with a large\ndispersion. The attenuation in our mid-IR selected sample is found ~ 2 mag\nhigher than that found globally in the universe or in UV and Halpha line\nselections in the same redshift range. This difference is well explained by an\nincrease of dust attenuation with the stellar mass, in global agreement with\nother recent studies. Starbursting galaxies do not systematically exhibit a\nhigh attenuation" }, { "anchor": "The Cloud Factory II: Gravoturbulent Kinematics of Resolved Molecular\n Clouds in a Galactic Potential: We present a statistical analysis of the gravoturbulent velocity fluctuations\nin molecular cloud complexes extracted from our \"Cloud Factory\" galactic-scale\nISM simulation suite. For this purpose, we produce non-LTE $^{12}$CO J=1-0\nsynthetic observations and apply the Principal Component Analysis (PCA)\nreduction technique on a representative sample of cloud complexes. The velocity\nfluctuations are self-consistently generated by different physical mechanisms\nat play in our simulations, which include galactic-scale forces, gas\nself-gravity, and supernova feedback. The statistical analysis suggests that,\neven though purely gravitational effects are necessary to reproduce standard\nobservational laws, they are not sufficient in most cases. We show that the\nextra injection of energy from supernova explosions plays a key role in\nestablishing the global turbulent field and the local dynamics and morphology\nof molecular clouds. Additionally, we characterise structure function scaling\nparameters as a result of cloud environmental conditions: some of the complexes\nare immersed in diffuse (inter-arm) or dense (spiral-arm) environments, and\nothers are influenced by embedded or external supernovae. In quiescent regions,\nwe obtain time-evolving trajectories of scaling parameters driven by\ngravitational collapse and supersonic turbulent flows. Our findings suggests\nthat a PCA-based statistical study is a robust method to diagnose the physical\nmechanisms that drive the gravoturbulent properties of molecular clouds. Also,\nwe present a new open source module, the PCAFACTORY, which smartly performs PCA\nto extract velocity structure functions from simulated or real data of the ISM\nin a user-friendly way. Software DOI: 10.5281/zenodo.3822718", "positive": "The kinematics of globular cluster populations in the E-MOSAICS\n simulations and their implications for the assembly history of the Milky Way: We present a detailed comparison of the Milky Way (MW) globular cluster (GC)\nkinematics with the 25 Milky Way-mass cosmological simulations from the\nE-MOSAICS project. While the MW falls within the kinematic distribution of GCs\nspanned by the simulations, the relative kinematics of its metal-rich\n($[\\rm{Fe/H}]>-1.2$) versus metal-poor ($[\\rm{Fe/H}]<-1.2$), and inner\n($r<8\\rm{kpc}$) versus outer ($r>8\\rm{kpc}$) populations are atypical for its\nmass. To understand the origins of these features, we perform a comprehensive\nstatistical analysis of the simulations, and find 18 correlations describing\nthe assembly of $L^*$ galaxies and their dark matter haloes based on their GC\npopulation kinematics. The correlations arise because the orbital distributions\nof accreted and in-situ GCs depend on the masses and accretion redshifts of\naccreted satellites, driven by the combined effects of dynamical fraction,\ntidal stripping, and dynamical heating. Because the kinematics of\nin-situ/accreted GCs are broadly traced by the metal-rich/metal-poor and\ninner/outer populations, the observed GC kinematics are a sensitive probe of\ngalaxy assembly. We predict that relative to the population of $L^*$ galaxies,\nthe MW assembled its dark matter and stellar mass rapidly through a combination\nof in-situ star formation, more than a dozen low-mass mergers, and $1.4\\pm1.2$\nearly ($z=3.1\\pm1.3$) major merger. The rapid assembly period ended early,\nlimiting the fraction of accreted stars. We conclude by providing detailed\nquantitative predictions for the assembly history of the MW." }, { "anchor": "Post-processing of galaxies due to major cluster mergers I. hints from\n galaxy colours and morphologies: Galaxy clusters, which underwent a recent ($\\leq3$ Gyr) major merger, offer a\nharsher environment due to the global hydrodynamical disturbance and the\nmerger-shock heated ICM. However, the aftermath of such extreme cluster\ninteractions on the member galaxy properties is not very well constrained. We\nexplore the integrated star formation properties of galaxies through galaxy\ncolours, as well as morphology buildup in three nearby ($0.040$). The anti-breathing of C IV can be well\nunderstood by the presence of a non-varying core component in addition to a\nreverberating broad-base component, consistent with earlier findings. The\ndeviation from canonical breathing introduces extra scatter (a\nluminosity-dependent bias) in single-epoch virial BH mass estimates due to\nintrinsic quasar variability, which underlies the long argued caveats of C IV\nsingle-epoch masses. Using the line dispersion instead of FWHM leads to less,\nalbeit still substantial, deviations from canonical breathing in most cases.\nOur results strengthen the need for reverberation mapping to provide reliable\nquasar BH masses, and quantify the level of variability-induced bias in\nsingle-epoch BH masses based on various lines.", "positive": "Deep optical images of Malin 1 reveal new features: We present Megacam deep optical images (g and r) of Malin 1 obtained with the\n6.5m Magellan/Clay telescope, detecting structures down to ~ 28 B mag arcsec-2.\nIn order to enhance galaxy features buried in the noise, we use a noise\nreduction filter based on the total generalized variation regularizator. This\nmethod allows us to detect and resolve very faint morphological features,\nincluding spiral arms, with a high visual contrast. For the first time, we can\nappreciate an optical image of Malin 1 and its morphology in full view. The\nimages provide unprecedented detail, compared to those obtained in the past\nwith photographic plates and CCD, including HST imaging. We detect two peculiar\nfeatures in the disk/spiral arms. The analysis suggests that the first one is\npossibly a background galaxy, and the second is an apparent stream without a\nclear nature, but could be related to the claimed past interaction between\nMalin 1 and the galaxy SDSSJ123708.91 + 142253.2. Malin 1 exhibits features\nsuggesting the presence of stellar associations, and clumps of molecular gas,\nnot seen before with such a clarity. Using these images, we obtain a diameter\nfor Malin 1 of 160 kpc, ~ 50 kpc larger than previous estimates. A simple\nanalysis shows that the observed spiral arms reach very low luminosity and mass\nsurface densities, to levels much lower than the corresponding values for the\nMilky Way." }, { "anchor": "Satellite Alignment: III. Satellite Galaxies Spatial Distribution and\n their Dependence on Redshift with A Novel Galaxy Finder: After extensively explored, broad agreement between observations and theories\nhas been reached that satellites are preferentially aligned with major axes of\ntheir host centrals. There are still some issues unsolved on this topic. In\nthis paper, we present studies on satellite spatial distribution. To fairly\ncompare with observations, we develop a novel galaxy finder and reconstruction\nalgorithm in hydrodynamical simulation, which is based on the projected mock\nimage, taking into account the full consideration of the point spread function,\npixel size, surface brightness limit, resolution and redshift dimming effects.\nWith galaxy samples constructed using such an algorithm, the satellite\nalignment is examined by comparing with observational results. It is found that\nthe observational alignment can be reproduced for red galaxies, which dominate\nthe sample in this study, but not for blue galaxies. Satellites' radial\ndistribution is also investigated. It exhibits that outer satellites within\nhost halos show stronger alignment signal than satellites in the inner regions,\nespecially for red satellites, which is in contrast with previous studies. The\ndisagreement is mainly due to extra galaxies identified by our new galaxy\nfinder, which are mainly located in the inner region of host halos. Our study\nillustrates that at lower redshift, the alignment strength becomes stronger,\nwhile radial distribution curve becomes flatter. This suggests differences in\nthe evolution of the angular distribution between satellites residing in the\ninner and outer halos, and implies that the post-infall evolution reduces the\noriginal alignment signal, that the impact decreases for satellites with later\ninfall times.", "positive": "From sub-solar to super-solar chemical abundances along the quasar main\n sequence: The 4D Eigenvector 1 sequence has proven to be a highly effective tool for\norganizing observational and physical properties of type 1 active galactic\nnuclei (AGN). In this paper, we present multiple measurements of metallicity\nfor the broad line region gas, from new or previously published data. We\ndemonstrate a consistent trend along the optical plane of the E1 (also known as\nthe quasar main sequence), defined by the line width of H$\\beta$ and by a\nparameter measuring the prominence of singly-ionized iron emission. The trend\ninvolves an increase from sub-solar metallicity in correspondence with extreme\nPopulation B (weak FeII emission, large H$\\beta$ FWHM) to metallicity several\ntens the solar value in correspondence with extreme Population A (very strong\nFeII optical emission, narrower H$\\beta$ profiles). The data establish the\nmetallicity as a correlate of the 4D E1/main sequence. If the very high\nmetallicity gas ($Z \\gtrsim 10 Z_\\odot$) is expelled from the sphere of\ninfluence of the central black hole, as indicated by the widespread evidence of\nnuclear outflows and disk wind in the case of sources radiating at high\nEddington ratio, then it is possible that the outflows from quasars played a\nrole in chemically enriching the host galaxy." }, { "anchor": "Equivalent widths of Lyman $\u03b1$ emitters in MUSE-Wide and MUSE-Deep: The aim of this study is to better understand the connection between the\nLyman $\\alpha$ rest-frame equivalent width (EW$_0$) and spectral properties as\nwell as ultraviolet (UV) continuum morphology by obtaining reliable EW$_0$\nhistograms for a statistical sample of galaxies and by assessing the fraction\nof objects with large equivalent widths. We used integral field spectroscopy\nfrom MUSE combined with broad-band data from the Hubble Space Telescope (HST)\nto measure EW$_0$. We analysed the emission lines of $1920$ Lyman $\\alpha$\nemitters (LAEs) detected in the full MUSE-Wide (one hour exposure time) and\nMUSE-Deep (ten hour exposure time) surveys and found UV continuum counterparts\nin archival HST data. We fitted the UV continuum photometric images using the\nGalfit software to gain morphological information on the rest-UV emission and\nfitted the spectra obtained from MUSE to determine the double peak fraction,\nasymmetry, full-width at half maximum, and flux of the Lyman $\\alpha$ line. The\ntwo surveys show different histograms of Lyman $\\alpha$ EW$_0$. In MUSE-Wide,\n$20\\%$ of objects have EW$_0 > 240$ \\r{A}, while this fraction is only $11\\%$\nin MUSE-Deep and $\\approx 16\\%$ for the full sample. This includes objects\nwithout HST continuum counterparts (one-third of our sample), for which we give\nlower limits for EW$_0$. The object with the highest securely measured EW$_0$\nhas EW$_0=589 \\pm 193$ \\r{A} (the highest lower limit being EW$_0=4464$ \\r{A}).\nWe investigate the connection between EW$_0$ and Lyman $\\alpha$ spectral or UV\ncontinuum morphological properties. The survey depth has to be taken into\naccount when studying EW$_0$ distributions. We find that in general, high\nEW$_0$ objects can have a wide range of spectral and UV morphological\nproperties, which might reflect that the underlying causes for high EW$_0$\nvalues are equally varied. (abridged)", "positive": "The Interstellar Dust Emission Spectrum, Going beyond the single\n temperature greybody: Context. Most of the modelling of interstellar dust infrared emission\nspectrum is done by assuming some variations around a single temperature\ngreybody approximation. For example, the foreground modelling of Planck mission\nmaps involves a unique dust temperature T along a given line-of-sight with a\nunique emissivity index \\b{eta}. The two parameters are then fitted and\ntherefore variable from one line-of-sight to the other. Aims. Our aim is to go\nbeyond that modelling in an economical way. Methods. We model the dust spectrum\nwith a temperature distribution around the mean value and show that only the\nsecond temperature moment matters. We advocate the use of the temperature\nlogarithm as the proper variable. Results. If the interstellar medium is not\ntoo heterogeneous, there is a universal analytical spectrum, which is derived\nhere, that goes beyond the greybody assumption. We show how the Cosmic\nMicrowave Background radiatively interacts with the dust spectrum (a\nnon-negligible corrective term at millimetre wavelengths). Finally, we\nconstruct a universal ladder of discrete temperatures which gives a minimal and\nfast description of dust emission spectra as measured by photometric mapping\ninstruments that lends itself to an almost linear fitting. This data modelling\ncan include contributions from the Cosmic Infrared Background fluctuations" }, { "anchor": "Mass loss from massive globular clusters in tidal fields: Massive globular clusters lose stars via internal and external processes.\nInternal processes include mainly two-body relaxation, while external processes\ninclude interactions with the Galactic tidal field. We perform a suite of\nN-body simulations of such massive clusters using three different\ndirect-summation N-body codes, exploring different Galactic orbits and particle\nnumbers. By inspecting the rate at which a star's energy changes as it becomes\nenergetically unbound from the cluster, we can neatly identify two populations\nwe call kicks and sweeps, that escape through two-body encounters internal to\nthe cluster and the external tidal field, respectively. We find that for a\ntypical halo globular cluster on a moderately eccentric orbit, sweeps are far\nmore common than kicks but the total mass loss rate is so low that these\nclusters can survive for tens of Hubble times. The different N-body codes give\nlargely consistent results, but we find that numerical artifacts may arise in\nrelation to the time step parameter of the Hermite integration scheme, namely\nthat the value required for convergent results is sensitive to the number of\nparticles.", "positive": "Universal conditional distribution function of [OII] luminosity of\n galaxies, and prediction for the [OII] luminosity function at redshift $z<3$: The star-forming emission line galaxies (ELGs) with strong [OII] doublet are\none of the main spectroscopic targets for the ongoing and upcoming fourth\ngeneration galaxy redshift surveys. In this work, we measure the [OII]\nluminosity $L_{\\mathrm{[OII]}}$ and the near-ultraviolet band absolute\nmagnitude $M_{\\mathrm{NUV}}$ for a large sample of galaxies in the redshift\nrange of $0.6\\leq z <1.45$ from the Public Data Release 2 (PDR-2) of the VIMOS\nPublic Extragalactic Redshift Survey (VIPERS). We aim to construct the\nintrinsic relationship between the $L_{\\mathrm{[OII]}}$ and $M_{\\mathrm{NUV}}$\nthrough Bayesian analysis. In particular, we develop two different methods to\nproperly correct for the incompleteness effect and observational errors in the\n[OII] emission line measurement. Our results indicate that the conditional\ndistribution of $L_{\\mathrm{[OII]}}$ at a given $M_{\\mathrm{NUV}}$ can be well\ndescribed by a universal probability distribution function (PDF), which is\nindependent of $M_{\\mathrm{NUV}}$ or redshift. Convolving the\n$L_{\\mathrm{[OII]}}$ conditional PDF with the NUV Luminosity function (LF)\navailable in the literature, we make a prediction for [OII] LFs at $z<3$. The\npredicted [OII] LFs are in good agreement with the observational results from\nthe literature. Finally, we utilize the predicted [OII] LFs to estimate the\nnumber counts of [OII] emitters for the Subaru Prime Focus Spectrograph (PFS)\nsurvey. This universal conditional PDF of $L_{\\mathrm{[OII]}}$ provides a novel\nway to optimize the source targeting strategy for [OII] emitters in future\ngalaxy redshift surveys, and to model [OII] emitters in theories of galaxy\nformation." }, { "anchor": "Galactic HI supershells: Kinetic energies and possible origin: The Milky Way, when viewed in the neutral hydrogen line emission, presents\nlarge structures called Galactic supershells (GSs). The origin of these\nstructures is still a subject of debate. The most common scenario invoked is\nthe combined action of strong winds from massive stars and their subsequent\nexplosion as supernova. The aim of this work is to determine the origin of 490\nGSs that belong to the Catalog of HI supershell candidates in the outer part of\nthe Galaxy. To know the physical processes that took place to create these\nexpanding structures, it is necessary to determine their kinetic energies. To\nobtain all the GS masses, we developed and used an automatic algorithm, which\nwas tested on 95 GSs whose masses were also estimated by hand. The estimated\nkinetic energies of the GSs vary from $1\\times10^{47}$ to $3.4\\times10^{51}$\nerg. Considering an efficiency of 20% for the conversion of mechanical stellar\nwind energy into the kinetic energy of the GSs, the estimated values of the GS\nenergies could be reached by stellar OB associations. For the GSs located at\nhigh Galactic latitudes, the possible mechanism for their creation could be\nattributed to collision with high velocity clouds (HVC). We have also analysed\nthe distribution of GSs in the Galaxy, showing that at low Galactic latitudes,\n$|b|<2^\\circ$, most of the structures in the third Galactic quadrant seem to be\nprojected onto the Perseus Arm. The detection of GSs at very high distances\nfrom the Galactic centre may be attributed to diffuse gas associated with the\ncircumgalactic medium of M31 and to intra-group gas in the Local Group\nfilament.", "positive": "A High Resolution Study of Carbon Radio Recombination Lines towards\n Cassiopeia A: Carbon Radio Recombination Lines trace the interface between molecular and\natomic gas. We present GMRT observations of Carbon Radio Recombination Lines\n(CRRL), C$\\alpha$244-C$\\alpha$250 towards Cassiopeia A. We use a novel\ntechnique of stacking the emission lines in the visibility domain to obtain,\nfor the first time, sub-pc resolution optical depth maps of these CRRLs. The\nemission shows a wide range of spatial and velocity structures, some of which\nare unresolved within our synthesis beam of 0.29 pc and velocity channel of\n0.55 km/s. These variations in the emission optical depth and line width are\nindicative of inhomogeneity and fragmentation in the intervening Perseus Arm\ngas. We compare the distribution of the CRRL emission with that of diffuse and\ndense molecular gas using existing CO and H$_2$CO studies. We find that the CO\nemission in the -47 km/s Perseus Arm component is primarily concentrated along\nan elongated structure detected in our CRRL maps, to the south of which lies\nthe high-density molecular clumps traced by H$_2$CO. This spatial distribution\nof CRRL and molecular tracers is similar to what one would observe for a Photo\nDissociation Region (PDR). In the other Perseus Arm component centered at -37\nkm/s, there is evidence for high column density (N$_{H_2}$ ~\n$10^{22}$cm$^{-2}$) molecular clumps embedded in diffuse CO as well as CRRL\nemission towards the center of Cassiopeia A. We propose that the CRRL emissions\ncoincident with molecular tracers originates from the line of sight integrated\ncomponent of the C$^{+}$ envelope of the molecular gas." }, { "anchor": "UV slope of z$\\sim$3 bright ($L>L^{*}$) Lyman-break galaxies in the\n COSMOS field: We analyse a unique sample of 517 bright ($L>L^{*}$) LBGs at redshift\nz$\\sim$3 in order to characterise the distribution of their UV slopes $\\beta$\nand infer their dust extinction under standard assumptions. We exploited\nmulti-band observations over 750 arcmin$^2$ of the COSMOS field that were\nacquired with three different ground-based facilities: the Large Binocular\nCamera (LBC) on the Large Binocular Telescope (LBT), the Suprime-Cam on the\nSUBARU telescope, and the VIRCAM on the VISTA telescope (ULTRAVISTA DR2). Our\nmulti-band photometric catalogue is based on a new method that is designed to\nmaximise the signal-to-noise ratio in the estimate of accurate galaxy colours\nfrom images with different point spread functions (PSF). We adopted an improved\nselection criterion based on deep Y-band data to isolate a sample of galaxies\nat $z\\sim 3 $ to minimise selection biases. We measured the UV slopes ($\\beta$)\nof the objects in our sample and then recovered the intrinsic probability\ndensity function of $\\beta$ values (PDF($\\beta$)), taking into account the\neffect of observational uncertainties through detailed simulations. The\ngalaxies in our sample are characterised by mildly red UV slopes with\n$<\\beta>\\simeq -1.70$ throughout the enitre luminosity range that is probed by\nour data ($-24\\lesssim M_{1600}\\lesssim -21$). The resulting dust-corrected\nstar formation rate density (SFRD) is $log(SFRD)\\simeq-1.6\nM_{\\odot}/yr/Mpc^{3}$, corresponding to a contribution of about 25% to the\ntotal SFRD at z$\\sim$3 under standard assumptions. Ultra-bright LBGs at $z \\sim\n3$ match the known trends, with UV slopes being redder at decreasing redshifts,\nand brighter galaxies being more highly dust extinct and more frequently\nstar-forming than fainter galaxies. [abridged]", "positive": "Finite temperature effects in Bose-Einstein Condensed dark matter halos: Once the critical temperature of a cosmological boson gas is less than the\ncritical temperature, a Bose-Einstein Condensation process can always take\nplace during the cosmic history of the universe. Zero temperature condensed\ndark matter can be described as a non-relativistic, Newtonian gravitational\ncondensate, whose density and pressure are related by a barotropic equation of\nstate, with barotropic index equal to one. In the present paper we analyze the\neffects of the finite dark matter temperature on the properties of the\nBose-Einstein Condensed dark matter halos. We formulate the basic equations\ndescribing the finite temperature condensate, representing a generalized\nGross-Pitaevskii equation that takes into account the presence of the thermal\ncloud. The static condensate and thermal cloud in thermodynamic equilibrium is\nanalyzed in detail, by using the Hartree-Fock-Bogoliubov and Thomas-Fermi\napproximations. The condensed dark matter and thermal cloud density and mass\nprofiles at finite temperatures are explicitly obtained. Our results show that\nwhen the temperature of the condensate and of the thermal cloud are much\nsmaller than the critical Bose-Einstein transition temperature, the zero\ntemperature density and mass profiles give an excellent description of the dark\nmatter halos. However, finite temperature effects may play an important role in\nthe early stages of the cosmological evolution of the dark matter condensates." }, { "anchor": "The role of mass and environment in the build up of the quenched galaxy\n population since cosmic noon: We conduct the first study of how the relative quenching probability of\ngalaxies depends on environment over the redshift range $0.5 < z < 3$, using\ndata from the UKIDSS Ultra-Deep Survey. By constructing the stellar mass\nfunctions for quiescent and post-starburst (PSB) galaxies in high, medium and\nlow density environments to $z = 3$, we find an excess of quenched galaxies in\ndense environments out to at least $z \\sim 2$. Using the growth rate in the\nnumber of quenched galaxies, combined with the star-forming galaxy mass\nfunction, we calculate the probability that a given star-forming galaxy is\nquenched per unit time. We find a significantly higher quenching rate in dense\nenvironments (at a given stellar mass) at all redshifts. Massive galaxies (M$_*\n> 10^{10.7}$ M$_{\\odot}$) are on average 1.7 $\\pm$ 0.2 times more likely to\nquench per Gyr in the densest third of environments compared to the sparsest\nthird. Finally, we compare the quiescent galaxy growth rate to the rate at\nwhich galaxies pass through a PSB phase. Assuming a visibility timescale of 500\nMyr, we find that the PSB route can explain $\\sim$ 50\\% of the growth in the\nquiescent population at high stellar mass (M$_* > 10^{10.7}$ M$_{\\odot}$) in\nthe redshift range $0.5 < z < 3$, and potentially all of the growth at lower\nstellar masses.", "positive": "Constraining the radio jet proper motion of the high-redshift quasar\n J2134-0419 at z=4.3: To date, PMN J2134-0419 (at a redshift z=4.33) is the second most distant\nquasar known with a milliarcsecond-scale morphology permitting direct estimates\nof the jet proper motion. Based on two-epoch observations, we constrained its\nradio jet proper motion using the very long baseline interferometry (VLBI)\ntechnique. The observations were conducted with the European VLBI Network (EVN)\nat 5 GHz on 1999 November 26 and 2015 October 6. We imaged the central 10-pc\nscale radio jet emission and modeled its brightness distribution. By\nidentifying a jet component at both epochs separated by 15.86 yr, a proper\nmotion of mu=0.035 +- 0.023 mas/yr is found. It corresponds to an apparent\nsuperluminal speed of beta_a=4.1 +- 2.7 c . Relativistic beaming at both epochs\nsuggests that the jet viewing angle with respect to the line of sight is\nsmaller than 20 deg, with a minimum bulk Lorentz factor Gamma=4.3. The small\nvalue of the proper motion is in good agreement with the expectations from the\ncosmological interpretation of the redshift and the current cosmological model.\nAdditionally we analyzed archival Very Large Array observations of J2143-0419\nand found indication of a bent jet extending to ~30 kpc." }, { "anchor": "Observations of Anomalous Microwave Emission from HII regions: In this brief review, I give a summary of the observations of Anomalous\nMicrowave Emission (AME) from HII regions. AME has been detected in, or in the\nvicinity of, HII regions. Given the difficulties in measuring accurate SEDs\nover a wide range of frequencies and in complex environments, many of these\ndetections require more data to confirm them as emitting significant AME. The\ncontribution from optically thick free-free emission from UCHII regions may be\nalso be significant in some cases. The AME emissivity, defined as the ratio of\nthe AME brightness to the 100 micron brightness, is comparable to the value\nobserved in high-latitude diffuse cirrus in some regions, but is significantly\nlower in others. However, this value is dependent on the dust temperature. More\ndata, both at high frequencies (>5 GHz) and high resolution (~1 arcmin or\nbetter) is required to disentangle the emission processes in such complex\nregions.", "positive": "Increasing the Scientific Return of Stellar Orbits at the Galactic\n Center: We report a factor of $\\sim$3 improvement in Keck Laser Guide Star Adaptive\nOptics (LGSAO) astrometric measurements of stars near the Galaxy's supermassive\nblack hole (SMBH). By carrying out a systematic study of M92, we have produced\na more accurate model for the camera's optical distortion. Updating our\nmeasurements with this model, and accounting for differential atmospheric\nrefraction, we obtain estimates of the SMBH properties that are a factor of\n$\\sim$2 more precise, and most notably, increase the likelihood that the black\nhole is at rest with respect to the nuclear star cluster. These improvements\nhave also allowed us to extend the radius to which stellar orbital parameter\nestimates are possible by a factor of 2." }, { "anchor": "A 85 kpc Halpha tail behind 2MASX J11443212+2006238 in A1367: We report the detection of an Halpha trail of 85 kpc projected length behind\ngalaxy 2MASX J11443212+2006238 in the nearby cluster of galaxies Abell 1367.\nThis galaxy was discovered to possess an extended component in earlier, deeper\nH$\\alpha$ observations carried out with the Subaru telescope. However, lying at\nthe border of the Subaru field, the extended Halpha tail was cut out,\npreventing the determination of its full extent. We fully map this extent here,\nalbeit the shallower exposure.", "positive": "Dust emissivity in resolved spiral galaxies: Context: The far-infrared (FIR) and sub-millimeter (submm) emissivity of the\nMilky Way (MW) cirrus is an important benchmark for dust grain models. Dust\nmasses in other galaxies are generally derived from the FIR/submm using the\nemission properties of these MW-calibrated models. Aims: We seek to derive the\nFIR/submm emissivity in nine nearby spiral galaxies to check its compatibility\nwith MW cirrus measurements. Methods: We obtained values of the emissivity at\n70 to 500 um, using maps of dust emission from the Herschel satellite and of\ngas surface density from the THINGS and HERACLES surveys on a scale generally\ncorresponding to 440 pc. We studied the variation of the emissivity with the\nsurface brightness ratio I(250um)/I(500um), a proxy for the intensity of the\ninterstellar radiation field heating the dust. Results: We find that the\naverage value of the emissivity agrees with MW estimates for pixels sharing the\nsame color as the cirrus, namely, for I(250um)/I(500um) = 4.5. For\nI(250um)/I(500um) > 5, the measured emissivity is instead up to a factor ~2\nlower than predicted from MW dust models heated by stronger radiation fields.\nRegions with higher I(250um)/I(500um) are preferentially closer to the galactic\ncenter and have a higher overall (stellar+gas) surface density and molecular\nfraction. The results do not depend strongly on the adopted CO-to-molecular\nconversion factor and do not appear to be affected by the mixing of heating\nconditions. Conclusions: Our results confirm the validity of MW dust models at\nlow density, but are at odds with predictions for grain evolution in higher\ndensity environments. If the lower-than-expected emissivity at high\nI(250um)/I(500um) is the result of intrinsic variations in the dust properties,\nit would imply an underestimation of the dust mass surface density of up to a\nfactor ~2 when using current dust models." }, { "anchor": "Si iv Column Densities Predicted from Non-Equilibrium Ionization\n Simulations of Turbulent Mixing Layers and High-Velocity Clouds: We present predictions of the Si iv ions in turbulent mixing layers (TMLs)\nbetween hot and cool gas and in cool high-velocity clouds (HVCs) that travel\nthrough a hot halo, complementing the C iv, N v, and O vi predictions in Kwak &\nShelton, Kwak et al., and Henley et al. We find that the Si iv ions are most\nabundant in regions where the hot and cool gases first begin to mix or where\nthe mixed gas has cooled significantly. The predicted column densities of high\nvelocity Si iv and the predicted ratios of Si iv to C iv and O vi found on\nindividual sightlines in our HVC simulations are in good agreement with\nobservations of high velocity gas. Low velocity Si iv is also seen in the\nsimulations, as a result of decelerated gas in the case of the HVC simulations\nand when looking along directions that pass perpendicular to the direction of\nmotion in the TML simulations. The ratios of low velocity Si iv to C iv and O\nvi in the TML simulations are in good agreement with those recorded for Milky\nWay halo gas, while the ratio of Si iv to O vi from the decelerated gas in the\nHVC simulations is lower than that observed at normal velocity in the Milky Way\nhalo. We attribute the shortfall of normal velocity Si iv to not having modeled\nthe effects of photoionization and, following Henley et al., consider a\ncomposite model that includes decelerated HVC gas, supernova remnants, galactic\nfountain gas, and the effect of photoionization.", "positive": "The physical properties and evolution of Lyalpha emitting galaxies: A significant fraction of high redshift starburst galaxies presents strong Ly\nalpha emission. Understanding the nature of these galaxies is important to\nassess the role they played in the early Universe and to shed light on the\nrelation between the narrow band selected Lyalpha emitters and the Lyman break\ngalaxies: are the Lyalpha emitters a subset of the general LBG population? or\ndo they represent the youngest galaxies in their early phases of formation? We\nstudied a sample of UV continuum selected galaxies from z~2.5 to z~6 (U, B, V\nand i-dropouts) from the GOODS-South survey, that have been observed\nspectroscopically. Using the GOODS-MUSIC catalog we investigated their physical\nproperties, such as total masses, ages, SFRs, extinction etc as determined from\na spectrophotometric fit to the multi-wavelength (U band to mid-IR) SEDs, and\ntheir dependence on the emission line characteristics. In particular we\ndetermined the nature of the LBGs with Lyalpha in emission and compared them to\nthe properties of narrow band selected Lyalpha emitters. For U and B-dropouts\nwe also compared the properties of LBGs with and without the Lyalpha emission\nline." }, { "anchor": "The Close AGN Reference Survey (CARS): SOFIA detects spatially-resolved\n [CII] emission in the luminous AGN HE0433-1028: We report spatially-resolved [CII]$\\lambda 158$ $\\mu$m observations of HE\n0433-1028, which is the first detection of a nearby luminous AGN (redshift\n0.0355) with FIFI-LS onboard the airborne observatory SOFIA. We compare the\nspatially-resolved star formation tracers [CII], as provided by our SOFIA\nobservations, and H$\\alpha$ from MUSE optical integral-field spectroscopy. We\nfind that the [CII] emission is mainly matching the extended star formation as\ntraced by the extinction-corrected H$\\alpha$ line emission but some additional\nflux is present. While a larger sample is needed to statistically confirm our\nfindings and investigate possible dependencies on AGN luminosity and star\nformation rate, our study underlines the necessity of collecting a\nspatially-resolved optical-FIR dataset for nearby AGNs, and shows that it is\ntechnically feasible to collect such datasets with FIFI-LS onboard SOFIA.", "positive": "Strong C IV emission from star-forming galaxies: a case for high Lyman\n continuum photon escape: Finding reliable indicators of Lyman continuum (LyC) photon leakage from\ngalaxies is essential in order to infer their escape fraction in the epoch of\nreionisation, where direct measurements of LyC flux are impossible. To this\nend, here we investigate whether strong C IV $\\lambda \\lambda 1548,1550$\nemission in the rest-frame UV spectra of galaxies traces conditions ripe for\nample production and escape of LyC photons. We compile a sample of 19\nstar-forming galaxies in the redshift range $z=3.1-4.6$ from the VANDELS survey\nthat exhibit strong C IV emission, producing a stacked spectrum where all major\nrest-UV emission lines are clearly detected. Best-fitting spectral energy\ndistribution models containing both stellar and nebular emission suggest the\nneed for low stellar metallicities ($Z=0.1-0.2\\,Z_\\odot$), young stellar ages\n($\\log(\\rm{age/yr}) = 6.1-6.5$), a high ionisation parameter ($\\log U = -2$)\nand little to no dust attenuation ($E(B-V)=0.00-0.01$). However, these models\nare unable to fully reproduce the observed C IV and He II line strengths. We\nfind that the Ly$\\alpha$ line in the stacked spectrum is strong and peaks close\nto the systemic velocity, features that are indicative of significant LyC\nphoton leakage along the line-of-sight. The covering fractions of\nlow-ionisation interstellar absorption lines are also low implying LyC escape\nfraction in the range $\\approx 0.05-0.30$, with signatures of outflowing gas.\nFinally, C IV/C III] ratios of >0.75 for a subset of individual galaxies with\nreliable detections of both lines are also consistent with physical conditions\nthat enable significant LyC leakage. Overall, we report that multiple\nspectroscopic indicators of LyC leakage are present in the stacked spectrum of\nstrong C IV emitting galaxies, potentially making C IV an important tracer of\nLyC photon escape at $z>6$." }, { "anchor": "Planet Formation in AB Aurigae: Imaging of the inner gaseous Spirals\n observed inside the Dust Cavity: We report the results of ALMA observations of a protoplanetary disk\nsurrounding the Herbig Ae star AB Aurigae. We obtained high-resolution (0.1\";\n14 au) images in $^{12}$CO (J=2-1) emission and in dust continuum at the\nwavelength of 1.3 mm. The continuum emission is detected at the center and at\nthe ring with a radius of $\\sim$ 120 au. The CO emission is dominated by two\nprominent spirals within the dust ring. These spirals are trailing and appear\nto be about 4 times brighter than their surrounding medium. Their kinematics is\nconsistent with Keplerian rotation at an inclination of 23 degree. The apparent\ntwo-arm-spiral pattern is best explained by tidal disturbances created by an\nunseen companion located at 60--80 au, with dust confined in the pressure bumps\ncreated outside this companion orbit. An additional companion at r of 30 au,\ncoinciding with the peak CO brightness and a large pitch angle of the spiral,\nwould help to explain the overall emptiness of the cavity. Alternative\nmechanisms to excite the spirals are discussed. The origin of the large pitch\nangle detected here remain puzzling.", "positive": "SPADES: a Stellar PArameters DEtermination Software: With the large amounts of spectroscopic data available today and the very\nlarge surveys to come (e.g. Gaia), the need for automatic data analysis\nsoftware is unquestionable. We thus developed an automatic spectra analysis\nprogram for the determination of stellar parameters: radial velocity, effective\ntemperature, surface gravity, micro-turbulence, metallicity and the elemental\nabundances of the elements present in the spectral range. Target stars for this\nsoftware should include all types of stars. The analysis method relies on a\nline by line comparison of the spectrum of a target star to a library of\nsynthetic spectra. The idea is built on the experience acquired in developing\nthe TGMET (Katz et al. 1998 and Soubiran et al. 2003) ETOILE (Katz 2001) and\nAbbo (Bonifacio & Caffau 2003) softwares. The method is presented and the\nperformances are illustrated with GIRAFFE-like simulated spectra with high\nresolution (R = 25000), with high and low signal to noise ratios (down to SNR=\n30). These spectra should be close to what could be targeted by the Gaia-ESO\nSurvey (GCDS)." }, { "anchor": "The impact of reionization on the formation of supermassive black hole\n seeds: Direct collapse black holes (DCBHs) formed from the collapse of\natomically-cooled primordial gas in the early Universe are strong candidates\nfor the seeds of supermassive BHs. DCBHs are thought to form in atomic cooling\nhaloes in the presence of a strong molecule-dissociating, Lyman-Werner (LW)\nradiation field. Given that star forming galaxies are likely to be the source\nof the LW radiation in this scenario, ionizing radiation from these galaxies\nmay accompany the LW radiation. We present cosmological simulations resolving\nthe collapse of primordial gas into an atomic cooling halo, including the\neffects of both LW and ionizing radiation. We find that in cases where the gas\nis not self-shielded from the ionizing radiation, the collapse can be delayed\nby ~ 25 Myr. When the ionized gas does collapse, the free electrons that are\npresent catalyze H2 formation. In turn, H2 cooling becomes efficient in the\ncenter of the halo, and DCBH formation is prevented. We emphasize, however,\nthat in many cases the gas collapsing into atomic cooling haloes at high\nredshift is self-shielding to ionizing radiation. Therefore, it is only in a\nfraction of such haloes in which DCBH formation is prevented due to\nreionization.", "positive": "Cosmic dust VIII: This is an editorial to the special issue on Cosmic Dust VIII." }, { "anchor": "The soft X-ray background with Suzaku: I. Milky Way halo: We present measurements of the soft X-ray background emission for 130 Suzaku\nobservations at $75^\\circ15^\\circ$ obtained from 2005\nto 2015, covering nearly one solar cycle. In addition to the standard soft\nX-ray background model consisting of the local hot bubble and the Milky Way\nHalo (MWH), we include a hot collisional-ionization-equilibrium component with\na temperature of $\\sim 0.8$ keV to reproduce spectra of a significant fraction\nof the lines of sight. Then, the scatter in the relation between the emission\nmeasure vs. temperature of the MWH component is reduced. Here, we exclude time\nranges with high count rates to minimize the effect of the solar wind charge\nexchange (SWCX). However, the spectra of almost the same lines of sight are\ninconsistent. The heliospheric SWCX emissions likely contaminate and gives a\nbias in measurements of temperature and the emission measure of the MWH.\nExcluding the data around the solar maximum and using the data taken before the\nend of 2009, at $|b|>35^\\circ$ and $105^\\circ -1.4$) SLFSs, $\\sim$15\\% versus $\\sim$60%, respectively. The OVI frequency\nfor the HM and LM pLLSs is, however, similar $\\sim$60%. The SLFSs and pLLSs\nwith no OVI are consistent with gas being in a single-phase, while those with\nOVI trace multiphase gas. We find that the OVI velocity widths and column\ndensities have different distributions in LM and HM gas. We observe a strong\ncorrelation between OVI column density and metallicity. The strongest\n(logN(OVI) $\\gtrsim 14$) and broadest OVI absorbers are nearly systematically\nfound to be associated with HM gas, while weaker OVI absorbers are found in\nboth LM and HM HI-bearing gas. From comparisons with galaxy and OVI surveys, we\nconclude absorbers with logN(OVI) $\\gtrsim 14$ most likely arise in the\ncircumgalactic medium (CGM) of star-forming galaxies, with the broadest and\nstrongest possibly tracing galaxy outflows. Absorbers with weak OVI most likely\ntrace the extended CGM or intergalactic medium (IGM), while those without OVI\nin all likelihood originate in the IGM.", "positive": "Star formation quenching stages of active and non-active galaxies: The mechanisms that bring galaxies to strongly reduce their star formation\nactivity (star-formation quenching) is still poorly understood. To better study\ngalaxy evolution, we propose a classification based on the maps of the ionised\nhydrogen distribution, traced by kpc-resolved, equivalent width of H$\\alpha$\nmaps, and the nuclear activity of the galaxies using information from the BPT\ndiagnostic diagrams. Using these tools, we group a sample of 238 galaxies from\nthe CALIFA survey in six quenching stages (QS): objects dominated by recent\nstar formation; systems that present a quiescent-nuclear-ring structure in\ntheir centre; galaxies that are centrally-quiescent; galaxies with no clear\npattern in their ionisation gas distribution - mixed; systems that posses only\na few star-forming regions - nearly-retired, or galaxies that are completely\nquiescent - fully-retired. Regarding their nuclear activity, we further divide\nthe galaxies into two groups - active systems that host a weak or strong AGN in\ntheir centre, and non-active objects. Galaxies grouped into quenching stage\nclasses occupy specific locations on the star-formation-rate versus stellar\nmass diagram. The \"Blue cloud\" is populated by the star-forming and the\nquiescent-nuclear-ring galaxies, the \"Green valley\" is populated by\ncentrally-quiescent and mixed systems, \"Red sequence\" by the nearly- and\nfully-retired objects. Generally, galaxies that host a weak or strong AGN show\nproperties, comparable to the non-active counterparts at the same quenching\nstages, except for the AGN-hosting star-forming systems. The degree of the\nstar-formation quenching increases along the present emission-line pattern\nsequence from star-forming to fully-retired. The proposed emission-line classes\nreinforce the \"inside-out\" quenching scenario, which foresees that the\nsuppression of the star-formation begins from the central regions of the\ngalaxies." }, { "anchor": "Detecting and Characterizing Young Quasars I: Systemic Redshifts and\n Proximity Zones Measurements: In a multi-wavelength survey of $13$ quasars at $5.8\\lesssim z\\lesssim6.5$,\nthat were pre-selected to be potentially young, we find five objects with\nextremely small proximity zone sizes that may imply UV-luminous quasar\nlifetimes of $\\lesssim 100,000$ years. Proximity zones are regions of enhanced\ntransmitted flux in the vicinity of the quasars that are sensitive to the\nquasars' lifetimes because the intergalactic gas has a finite response time to\ntheir radiation. We combine sub-mm observations from the Atacama Large\nMillimetre Array (ALMA) and the NOrthern Extended Millimeter Array (NOEMA), as\nwell as deep optical and near-infrared spectra from medium-resolution\nspectrograph on the Very Large Telescope (VLT) and on the Keck telescopes, in\norder to identify and characterize these new young quasars, which provide\nvaluable clues about the accretion behavior of supermassive black holes (SMBHs)\nin the early universe, and pose challenges on current black hole formation\nmodels to explain the rapid formation of billion solar mass black holes. We\nmeasure the quasars' systemic redshifts, black hole masses, Eddington ratios,\nemission line luminosities, and star formation rates of their host galaxies.\nCombined with previous results we estimate the fraction of young objects within\nthe high-redshift quasar population at large to be $5\\%\\lesssim f_{\\rm\nyoung}\\lesssim 10\\%$. One of the young objects, PSO J158-14, shows a very\nbright dust continuum flux ($F_{\\rm cont}=3.46\\pm 0.02\\,\\rm mJy$), indicating a\nhighly star-bursting host galaxy with a star formation rate of approximately\n$1420\\,M_{\\odot}\\,\\rm yr^{-1}$.", "positive": "Dissipative dark matter halos: The steady state solution: Dissipative dark matter, where dark matter particle properties closely\nresemble familiar baryonic matter, is considered. Mirror dark matter, which\narises from an isomorphic hidden sector, is a specific and theoretically\nconstrained scenario. Other possibilities include models with more generic\nhidden sectors that contain massless dark photons (unbroken $U(1)$ gauge\ninteractions). Such dark matter not only features dissipative cooling\nprocesses, but is also assumed to have nontrivial heating sourced by ordinary\nsupernovae (facilitated by the kinetic mixing interaction). The dynamics of\ndissipative dark matter halos around rotationally supported galaxies,\ninfluenced by heating as well as cooling processes, can be modelled by fluid\nequations. For a sufficiently isolated galaxy with stable star formation rate,\nthe dissipative dark matter halos are expected to evolve to a steady state\nconfiguration which is in hydrostatic equilibrium and where heating and cooling\nrates locally balance. Here, we take into account the major cooling and heating\nprocesses, and numerically solve for the steady state solution under the\nassumptions of spherical symmetry, negligible dark magnetic fields, and that\nsupernova sourced energy is transported to the halo via dark radiation. For the\nparameters considered, and assumptions made, we were unable to find a\nphysically realistic solution for the constrained case of mirror dark matter\nhalos. Halo cooling generally exceeds heating at realistic halo mass densities.\nThis problem can be rectified in more generic dissipative dark matter models,\nand we discuss a specific example in some detail." }, { "anchor": "Witnessing the transformation of a quasar host galaxy at z=1.6: A significant minority of high redshift radio galaxy (HzRG) candidates show\nextremely red broad band colours and remain undetected in emission lines after\noptical `discovery' spectroscopy. In this paper we present deep GTC optical\nimaging and spectroscopy of one such radio galaxy, 5C 7.245, with the aim of\nbetter understanding the nature of these enigmatic objects. Our g-band image\nshows no significant emission coincident with the stellar emission of the host\ngalaxy, but does reveal faint emission offset by ~3\" (26 kpc) therefrom along a\nsimilar position angle to that of the radio jets, reminiscent of the `alignment\neffect' often seen in the optically luminous HzRGs. This offset g-band source\nis also detected in several UV emission lines, giving it a redshift of 1.609,\nwith emission line flux ratios inconsistent with photoionization by young stars\nor an AGN, but consistent with ionization by fast shocks. Based on its unusual\ngas geometry, we argue that in 5C 7.245 we are witnessing a rare (or rarely\nobserved) phase in the evolution of quasar hosts when stellar mass assembly,\naccretion onto the back hole, and powerful feedback activity has eradicated its\ncold gas from the central ~20 kpc, but is still in the process of cleansing\ncold gas from its extended halo.", "positive": "JWST's PEARLS: a new lens model for ACT-CL J0102$-$4915, \"EL Gordo'',\n and the first red supergiant star at cosmological distances discovered by\n JWST: The first JWST data on the massive colliding cluster El Gordo confirm 23\nknown families of multiply lensed images and identify 8 new members of these\nfamilies. Based on these families, which have been confirmed spectroscopically\nby MUSE, we derived an initial lens model. This model guided the identification\nof 37 additional families of multiply lensed galaxies, among which 28 are\nentirely new systems, and 9 were previously known. The initial lens model\ndetermined geometric redshifts for the 37 new systems. The geometric redshifts\nagree reasonably well with spectroscopic or photometric redshifts when those\nare available. The geometric redshifts enable two additional models that\ninclude all 60 families of multiply lensed galaxies spanning a redshift range\n$20.8$ and has an estimated virial mass close the maximum\nmass allowed by standard cosmological models. The JWST images also reveal the\npresence of small-mass perturbers that produce small lensing distortions. The\nsmallest of these is consistent with being a dwarf galaxy at $z=0.87$ and has\nan estimated mass of $3.8\\times10^9$~\\Msol, making it the smallest substructure\nfound at $z>0.5$. The JWST images also show several candidate caustic-crossing\nevents. One of them is detected at high significance at the expected position\nof the critical curve and is likely a red supergiant star at $z=2.1878$. This\nwould be the first red supergiant found at cosmological distances. The cluster\nlensing should magnify background objects at $z>6$, making more of them visible\nthan in blank fields of similar size, but there appears to be a deficiency of\nsuch objects." }, { "anchor": "Host galaxy properties and environment of obscured and unobscured X-ray\n selected Active Galactic Nuclei in the COSMOS survey: We analyse different photometric and spectroscopic properties of active\ngalactic nuclei (AGNs) and quasars (QSOs) selected by their mid-IR power-law\nand X-ray emission from the COSMOS survey. We use a set of star-forming\ngalaxies as a control sample to compare with the results. We have considered\nsamples of obscured (HR > -0.2) and unobscured (HR < -0.2) sources including\nAGNs with $L_X$ < $10^{44}$ erg s$^{-1}$, as well as QSOs ($L_X$ > $10^{44}$\nerg s$^{-1}$) with 1.4 < z < 2.5. We also study the typical environment of\nthese samples, by assessing neighbouring galaxy number density and neighbour\nproperties such as colour, stellar mass and star formation rate. We find that\nthe UV/optical and mid-infrared colour distribution of the different AGN types\ndiffer significantly. Also, we obtain most of AGNs and QSOs to be more compact\nwhen compared to the sample of SF galaxies. In general we find that the stellar\nmass distribution of the different AGN sample are similar, obtaining only a\ndifference of $\\Delta\\overline{\\mathrm{log}M}=0.3$ dex ($M_{\\odot}$) between\nunobscured and obscured QSOs. Obscured and unobscured AGNs and QSOs reside in\ndifferent local environment at small ($r_p$ < 100 kpc) scales. Our results\nsupport previous findings where AGN type correlates with environment. These\ndifferences and those found in AGN host properties cast out the simplest\nunified model in which obscuration is purely an orientation effect.", "positive": "Rapid Filamentary Accretion as the Origin of Extended Thin Discs: Galactic outflows driven by stellar feedback are crucial for explaining the\ninefficiency of star formation in galaxies. Although strong feedback can\npromote the formation of galactic discs by limiting star formation at early\ntimes and removing low angular momentum gas, it is not understood how the same\nfeedback can result in diverse objects such as elliptical galaxies or razor\nthin spiral galaxies. We investigate this problem using cosmological zoom-in\nsimulations of two galaxies forming within $10^{12}~\\mathrm{M_\\odot}$ halos\nwith almost identical mass accretion histories and halo spin parameters.\nHowever, the two resulting galaxies end up with very different bulge-to-disc\nratios at $z = 0$. At $z>1.5$, the two galaxies feature a surface density of\nstar formation $\\Sigma_{\\rm SFR}\\simeq 10~\\mathrm{M_\\odot}~{\\rm yr}^{-1}~{\\rm\nkpc}^{-2}$, leading to strong outflows. After the last starburst episode, both\ngalaxies feature a dramatic gaseous disc growth from 1~kpc to 5~kpc during\n1~Gyr, a decisive event we dub \"the Grand Twirl\". After this event, the\nevolutionary tracks diverge strongly, with one galaxy ending up as a\nbulge-dominated galaxy, whereas the other ends up as a disc-dominated galaxy.\nThe origins of this dichotomy are the angular momentum of the accreted gas, and\nwhether it adds constructively to the initial disc angular momentum. The\nbuild-up of this extended disc leads to a rapid lowering of $\\Sigma_{\\rm SFR}$\nby over two orders of magnitude with $\\Sigma_{\\rm SFR} \\lesssim\n0.1~\\mathrm{M_\\odot}~{\\rm yr}^{-1}~{\\rm kpc}^{-2}$, in remarkable agreement\nwith what is derived from Milky Way stellar populations. As a consequence,\nsupernovae explosions are spread out and cannot launch galactic outflows\nanymore, allowing for the persistence of a thin, gently star forming, extended\ndisc." }, { "anchor": "Exploring the Role of Globular Cluster Specific Frequency on the Nova\n Rates in Three Virgo Elliptical Galaxies: It has been proposed that a galaxy's nova rate might be enhanced by the\nproduction of nova progenitor binaries in the dense cores of its globular\nclusters (GCs). To explore this idea, relative nova rates in three Virgo\nelliptical galaxies, M87, M49 and M84, which have significantly different GC\nspecific frequencies ($S_{N}$) of 14, 3.6, and 1.6, respectively, were measured\nover the course of 4 epochs spanning a period of 14 months. To simplify the\nanalysis, observations of the nearly equidistant galaxies were made on the same\nnights, with the same integration times, and through the same filter\n(H$\\alpha$), so that the relative numbers of novae discovered would reflect the\nrelative nova rates. At the conclusion of our survey we found a total of 27\nnovae associated with M87, 37 with M49, and 19 with M84. After correcting for\nsurvey completeness, we found annual nova rates of $154^{+23}_{-19}$,\n$189^{+26}_{-22}$, and $95^{+15}_{-14}$, for M87, M49, and M84, respectively,\ncorresponding to $K$-band luminosity-specific nova rates of $3.8\\pm1.0$,\n$3.4\\pm0.6$, and $3.0\\pm0.6$ novae per year per $10^{10}~L_{K,\\odot}$. The\noverall results of our study suggest that a galaxy's nova rate simply scales\nwith its luminosity, and is insensitive to its GC specific frequency. Two\nnovae, one in M87 and one in M84, were found to be spatially coincident with\nknown GCs. After correcting for the mass fraction in GCs, we estimate that\nnovae are likely enhanced relative to the field by at least an order of\nmagnitude in the GC systems of luminous Virgo ellipticals.", "positive": "Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby\n Star-Forming Galaxies: We use new ALMA observations to investigate the connection between dense gas\nfraction, star formation rate, and local environment across the inner region of\nfour local galaxies showing a wide range of molecular gas depletion times. We\nmap HCN (1-0), HCO$^+$ (1-0), CS (2-1), $^{13}$CO (1-0), and C$^{18}$O (1-0)\nacross the inner few kpc of each target. We combine these data with short\nspacing information from the IRAM large program EMPIRE, archival CO maps,\ntracers of stellar structure and recent star formation, and recent HCN surveys\nby Bigiel et al. and Usero et al. We test the degree to which changes in the\ndense gas fraction drive changes in the SFR. $I_{HCN}/I_{CO}$ (tracing the\ndense gas fraction) correlates strongly with $I_{CO}$ (tracing molecular gas\nsurface density), stellar surface density, and dynamical equilibrium pressure,\n$P_{DE}$. Therefore, $I_{HCN}/I_{CO}$ becomes very low and HCN becomes very\nfaint at large galactocentric radii, where ratios as low as $I_{HCN}/I_{CO}\n\\sim 0.01$ become common. The apparent ability of dense gas to form stars,\n$\\Sigma_{SFR}/\\Sigma_{dense}$ (where $\\Sigma_{dense}$ is traced by the HCN\nintensity and the star formation rate is traced by a combination of H$\\alpha$\nand 24$\\mu$m emission), also depends on environment.\n$\\Sigma_{SFR}/\\Sigma_{dense}$ decreases in regions of high gas surface density,\nhigh stellar surface density, and high $P_{DE}$. Statistically, these\ncorrelations between environment and both $\\Sigma_{SFR}/\\Sigma_{dense}$ and\n$I_{HCN}/I_{CO}$ are stronger than that between apparent dense gas fraction\n($I_{HCN}/I_{CO}$) and the apparent molecular gas star formation efficiency\n$\\Sigma_{SFR}/\\Sigma_{mol}$. We show that these results are not specific to\nHCN." }, { "anchor": "The dynamics of spiral arms in pure stellar disks: It has been believed that spirals in pure stellar disks, especially the ones\nspontaneously formed, decay in several galactic rotations due to the increase\nof stellar velocity dispersions. Therefore, some cooling mechanism, for example\ndissipational effects of the interstellar medium, was assumed to be necessary\nto keep the spiral arms. Here we show that stellar disks can maintain spiral\nfeatures for several tens of rotations without the help of cooling, using a\nseries of high-resolution three-dimensional $N$-body simulations of pure\nstellar disks. We found that if the number of particles is sufficiently large,\ne.g., $3\\times 10^6$, multi-arm spirals developed in an isolated disk can\nsurvive for more than 10 Gyrs. We confirmed that there is a self-regulating\nmechanism that maintains the amplitude of the spiral arms. Spiral arms increase\nToomre's $Q$ of the disk, and the heating rate correlates with the squared\namplitude of the spirals. Since the amplitude itself is limited by the value of\n$Q$, this makes the dynamical heating less effective in the later phase of\nevolution. A simple analytical argument suggests that the heating is caused by\ngravitational scattering of stars by spiral arms, and that the self-regulating\nmechanism in pure-stellar disks can effectively maintain spiral arms on a\ncosmological timescale. In the case of a smaller number of particles, e.g.,\n$3\\times 10^5$, spiral arms grow faster in the beginning of the simulation\n(while $Q$ is small) and they cause a rapid increase of $Q$. As a result, the\nspiral arms become faint in several Gyrs.", "positive": "Starburst-Driven Galactic Winds: Filament Formation and Emission\n Processes: We have performed a series of three-dimensional simulations of the\ninteraction of a supersonic wind with a non-spherical radiative cloud. These\nsimulations are motivated by our recent three-dimensional model of a\nstarburst-driven galactic wind interacting with an inhomogeneous disk, which\nshow that an optically emitting filament can be formed by the break-up and\nacceleration of a cloud into a supersonic wind. In this study we consider the\nevolution of a cloud with two different geometries (fractal and spherical) and\ninvestigate the importance of radiative cooling on the cloud's survival. We\nhave also undertaken a comprehensive resolution study in order to ascertain the\neffect of the assumed numerical resolution on the results. We find that the\nability of the cloud to radiate heat is crucial for its survival. While an\nadiabatic cloud is destroyed over a short period of time, a radiative cloud is\nbroken up via the Kelvin-Helmholtz instability into numerous small, dense\ncloudlets, which are drawn into the flow to form a filamentary structure. The\ndegree of fragmentation is highly dependent on the resolution of the\nsimulation, with the number of cloudlets formed increasing as the\nKelvin-Helmholtz instability is better resolved. Nevertheless, there is a clear\nqualitative trend, with the filamentary structure still persistent at high\nresolution. We confirm the mechanism behind the formation of the H-alpha\nemitting filaments found in our global simulations of a starburst-driven wind.\nBased on our resolution study, we conclude that bow shocks around accelerated\ngas clouds, and their interaction, are the main source of the soft X-ray\nemission observed in these galactic-scale winds. [ABRIDGED]" }, { "anchor": "The Shards of $\u03c9$ Centauri: We use the SDSS-Gaia catalogue to search for substructure in the stellar\nhalo. The sample comprises 62\\,133 halo stars with full phase space coordinates\nand extends out to heliocentric distances of $\\sim 10$ kpc. As actions are\nconserved under slow changes of the potential, they permit identification of\ngroups of stars with a common accretion history. We devise a method to identify\nhalo substructures based on their clustering in action space, using metallicity\nas a secondary check. This is validated against smooth models and numerical\nconstructed stellar halos from the Aquarius simulations. We identify 21\nsubstructures in the SDSS-Gaia catalogue, including 7 high significance, high\nenergy and retrograde ones.\n We investigate whether the retrograde substructures may be material stripped\noff the atypical globular cluster $\\omega$~Centauri. Using a simple model of\nthe accretion of the progenitor of the $\\omega$~Centauri, we tentatively argue\nfor the possible association of up to 5 of our new substructures (labelled Rg1,\nRg3, Rg4, Rg6 and Rg7) with this event. This sets a minimum mass of $5 \\times\n10^8 M_\\odot$ for the progenitor, so as to bring $\\omega$~Centauri to its\ncurrent location in action -- energy space. Our proposal can be tested by high\nresolution spectroscopy of the candidates to look for the unusual abundance\npatterns possessed by $\\omega$~Centauri stars.", "positive": "The HIPASS survey of the Galactic plane in Radio Recombination Lines: We present a Radio Recombination Line (RRL) survey of the Galactic Plane from\nthe HI Parkes All-sky Survey and associated Zone of Avoidance survey, which\nmapped the region l=196degr -- 0degr --52degr and |b| < 5degr at 1.4 GHz and\n14.4 arcmin resolution. We combine three RRLs, H168$\\alpha$, H167$\\alpha$, and\nH166$\\alpha$ to derive fully sampled maps of the diffuse ionized emission along\nthe inner Galactic plane. The velocity information, at a resolution of 20 km/s,\nallows us to study the spatial distribution of the ionized gas and compare it\nwith that of the molecular gas, as traced by CO. The longitude-velocity diagram\nshows that the RRL emission is mostly associated with CO gas from the molecular\nring and is concentrated within the inner 30degr of longitude. A map of the\nfree-free emission in this region of the Galaxy is derived from the\nline-integrated RRL emission, assuming an electron temperature gradient with\nGalactocentric radius of $496\\pm100$ K/kpc. Based on the thermal continuum map\nwe extracted a catalogue of 317 compact (<15 arcmin) sources, with flux\ndensities, sizes and velocities. We report the first RRL observations of the\nsouthern ionized lobe in the Galactic centre. The line profiles and velocities\nsuggest that this degree-scale structure is in rotation. We also present new\nevidence of diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are\ndetected in this survey. The He line is mostly observed towards HII regions,\nwhereas the C line is also detected further away from the source of ionization.\nThese data represent the first observations of diffuse C RRLs in the Galactic\nplane at a frequency of 1.4 GHz." }, { "anchor": "Keck OSIRIS AO LIRG Analysis: Feedback in the Nuclei of Luminous\n Infrared Galaxies: The role of feedback in triggering or quenching star formation and hence\ndriving galaxy evolution can be directly studied with high resolution integral\nfield observations. The manifestation of feedback in shocks is particularly\nimportant to examine in galaxy mergers, where violent interactions of gas takes\nplace in the interstellar medium during the course of the galactic collision.\nAs part of our effort to systematically study the local population of luminous\ninfrared galaxies within the Great Observatories All-Sky LIRG Survey, we\nundertook the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas\ndynamics in the inner kiloparsec regions of these systems at spatial scales of\na few 10s of parsecs. With high-resolution near-infrared adaptive\noptics-assisted integral-field observations taken with OSIRIS on the Keck\nTelescopes, we employ near-infrared diagnostics such as Brg and the\nro-vibrationally excited H2 lines to quantify the nuclear star formation rate\nand identify feedback associated with shocked molecular gas seen in 21 nearby\nluminous infrared galaxies. Shocked molecular gas is preferentially found in\nthe ultraluminous infrared systems, but may also be triggered at a lower\nluminosity, earlier merging stage. On circumnuclear scales, AGN have a strong\neffect on heating the surrounding molecular gas, though their coupling is not\nsimply driven by AGN strength but rather is complicated by orientation, dust\nshielding, density, and other factors. We find that the nuclear star formation\ncorrelates with merger class and diminishing projected nuclear separations.\nThese trends are largely consistent with the picture of merger-induced\nstarbursts within the center of galaxy mergers.", "positive": "Planetary Nebula Surveys: Past, Present and Future: In this review we cover the detection, identification and astrophysical\nimportance of planetary nebulae (PN). The legacy of the historic Perek &\nKohoutek and Acker et al. catalogues is briefly covered before highlighting the\nmore recent but significant progress in PN discoveries in our Galaxy and the\nMagellanic Clouds. We place particular emphasis on the major MASH and the IPHAS\ncatalogues, which, over the last decade alone, have essentially doubled\nGalactic and LMC PN numbers. We then discuss the increasing role and importance\nthat multi-wavelength data is playing in both the detection of candidate PN and\nthe elimination of PN mimics that have seriously biased previous PN\ncompilations. The prospects for future surveys and current efforts and\nprospects for PN detections in external galaxies are briefly discussed due to\ntheir value both as cosmic distance indicators and as kinematical probes of\ngalaxies and dark matter properties." }, { "anchor": "A striking relationship between dust extinction and radio detection in\n DESI QSOs: evidence for a dusty blow-out phase in red QSOs: We present the first eight months of data from our secondary target program\nwithin the ongoing Dark Energy Spectroscopic Instrument (DESI) survey. Our\nprogram uses a mid-infrared and optical colour selection to preferentially\ntarget dust-reddened QSOs that would have otherwise been missed by the nominal\nDESI QSO selection. So far we have obtained optical spectra for 3038\ncandidates, of which ~70% of the high-quality objects (those with robust\nredshifts) are visually confirmed to be Type 1 QSOs, consistent with the\nexpected fraction from the main DESI QSO survey. By fitting a dust-reddened\nblue QSO composite to the QSO spectra, we find they are well-fitted by a normal\nQSO with up to Av~4 mag of line-of-sight dust extinction. Utilizing radio data\nfrom the LOFAR Two-metre Sky Survey (LoTSS) DR2, we identify a striking\npositive relationship between the amount of line-of-sight dust extinction\ntowards a QSO and the radio detection fraction, that is not driven by\nradio-loud systems, redshift and/or luminosity effects. This demonstrates an\nintrinsic connection between dust reddening and the production of radio\nemission in QSOs, whereby the radio emission is most likely due to low-powered\njets or winds/outflows causing shocks in a dusty environment. On the basis of\nthis evidence we suggest that red QSOs may represent a transitional \"blow-out\"\nphase in the evolution of QSOs, where winds and outflows evacuate the dust and\ngas to reveal an unobscured blue QSO.", "positive": "Discovery of intergalactic bridges connecting two faint $z\\sim3$ quasars: We use MUSE/VLT to conduct a survey of $z\\sim3$ physical quasar pairs at\nclose separation with a fast observation strategy. Our aim is twofold: (i)\nexplore the Ly$\\alpha$ glow around the faint-end of the quasar population; (ii)\ntake advantage of the combined illumination of a quasar pair to unveil\nlarge-scale intergalactic structures extending between the two quasars. Here,\nwe report the results for a quasar pair ($z=3.020,3.008$; $i=21.84,22.15$),\nseparated by 11.6 arcsec (or 89 projected kpc). MUSE reveals filamentary\nLy$\\alpha$ structures extending between the two quasars with an average surface\nbrightness of SB$_{\\rm Ly\\alpha}=1.8\\times10^{-18}$ erg s$^{-1}$ cm$^{-2}$\narcsec$^{-2}$. Photoionization models of the constraints in the Ly$\\alpha$,\nHeII, and CIV line emissions show that the emitting structures are\nintergalactic bridges with an extent between $\\sim89$ and up to $\\sim600$ kpc.\nOur models rule out the possibility that the structure extends for $\\sim 2.9$\nMpc, i.e., the separation inferred from the uncertain systemic redshift\ndifference of the quasars if the difference was only due to the Hubble flow. At\nthe current spatial resolution and surface brightness limit, the average\nprojected width of an individual bridge is about 35 kpc. We also detect a\nstrong absorption in HI, NV, and CIV along the background sight-line at higher\n$z$, which we interpret as due to at least two components of cool, metal\nenriched, and relatively ionized CGM or IGM surrounding the quasar pair. Two\nadditional HI absorbers are detected along both quasar sight-lines at $\\sim\n-900$ and $-2800$ km s$^{-1}$ from the system, with the latter having\nassociated CIV absorption only along the foreground quasar sight-line. The\nabsence of galaxies in the MUSE field of view at the redshifts of these two\nabsorbers suggests that they trace large-scale structures or expanding shells\nin front of the quasar pair." }, { "anchor": "Detection of Interstellar H$_2$CCCHC$_3$N: The chemical pathways linking the small organic molecules commonly observed\nin molecular clouds to the large, complex, polycyclic species long-suspected to\nbe carriers of the ubiquitous unidentified infrared emission bands remain\nunclear. To investigate whether the formation of mono- and poly-cyclic\nmolecules observed in cold cores could form via the bottom-up reaction of\nubiquitous carbon-chain species with, e.g. atomic hydrogen, a search is made\nfor possible intermediates in data taken as part of the GOTHAM (GBT\nObservations of TMC-1 Hunting for Aromatic Molecules) project. Markov-Chain\nMonte Carlo (MCMC) Source Models were run to obtain column densities and\nexcitation temperatures. Astrochemical models were run to examine possible\nformation routes, including a novel grain-surface pathway involving the\nhydrogenation of C$_6$N and HC$_6$N, as well as purely gas-phase reactions\nbetween C$_3$N and both propyne (CH$_3$CCH) and allene (CH$_2$CCH$_2$), as well\nas via the reaction CN + H$_2$CCCHCCH. We report the first detection of\ncyanoacetyleneallene (H$_2$CCCHC$_3$N) in space toward the TMC-1 cold cloud\nusing the Robert C. Byrd 100 m Green Bank Telescope (GBT). Cyanoacetyleneallene\nmay represent an intermediate between less-saturated carbon-chains, such as the\ncyanopolyynes, that are characteristic of cold cores and the more\nrecently-discovered cyclic species like cyanocyclopentadiene. Results from our\nmodels show that the gas-phase allene-based formation route in particular\nproduces abundances of H$_2$CCCHC$_3$N that match the column density of\n$2\\times10^{11}$ cm$^{-2}$ obtained from the MCMC Source Model, and that the\ngrain-surface route yields large abundances on ices that could potentially be\nimportant as precursors for cyclic molecules.", "positive": "ALMA 400pc Imaging of a z=6.5 Massive Warped Disk Galaxy: We present 0.075 (~400 pc) resolution ALMA observations of the [CII] and dust\ncontinuum emission from the host galaxy of the z=6.5406 quasar, P036+03. We\nfind that the emission arises from a thin, rotating disk with an effective\nradius of 0.21\" (1.1 kpc). The velocity dispersion of the disk is consistent\nwith a constant value of 66.4+-1.0 km/s, yielding a scale height of 80+-30 pc.\nThe [CII] velocity field reveals a distortion that we attribute to a warp in\nthe disk. Modeling this warped disk yields an inclination estimate of 40.4+-1.3\ndegrees and a rotational velocity of 116+-3 km/s. The resulting dynamical mass\nestimate of (1.96+-0.10) x 10^10 Msun is lower than previous estimates, which\nstrengthens the conclusion that the host galaxy is less massive than expected\nbased on local scaling relations between the black hole mass and the host\ngalaxy mass. Using archival MUSE Ly-alpha observations, we argue that\ncounter-rotating halo gas could provide the torque needed to warp the disk. We\nfurther detect a region with excess (15-sigma) dust continuum emission, which\nis located 1.3 kpc northwest of the galaxy's center and is gravitationally\nunstable (Toomre-Q < 0.04). We posit this is a star-forming region whose\nformation was triggered by the warp, because the region is located within a\npart of the warped disk where gas can efficiently lose angular momentum. The\ncombined ALMA and MUSE imaging provides a unique view of how gas interactions\nwithin the disk-halo interface can influence the growth of massive galaxies\nwithin the first billion years of the universe." }, { "anchor": "Local starburst conditions and formation of GRB 980425 / SN 1998bw\n within a collisional ring: We present the first spatially resolved study of molecular gas in the\nvicinity of a Gamma Ray Burst, using CO(2-1) emission line observations with\nthe Atacama Large Millimetre Array (ALMA) at ~50 pc scales. The host galaxy of\nGRB 980425 contains a ring of high column density HI gas which is likely to\nhave formed due to a collision between the GRB host and its companion galaxy,\nwithin which the GRB is located. We detect eleven molecular gas clumps in the\ngalaxy, seven of which are within the gas ring. The clump closest to the GRB\nposition is at a projected separation of ~280 pc. Although it is plausible that\nthe GRB progenitor was ejected from clusters formed in this clump, we argue\nthat the in situ formation of the GRB progenitor is the most likely scenario.\nWe measure the molecular gas masses of the clumps and find them to be\nsufficient for forming massive star clusters. The molecular gas depletion times\nof the clumps show a variation of ~2 dex, comparable with the large variation\nin depletion times found in starburst galaxies in the nearby Universe. This\ndemonstrates the presence of starburst modes of star formation on local scales\nin the galaxy, even while the galaxy as a whole cannot be categorised as a\nstarburst based on its global properties. Our findings suggest that the\nprogenitor of GRB 9802425 was originated in a young massive star cluster formed\nin the starburst mode of star formation.", "positive": "Hidden Gems on a Ring: Infant Massive Clusters and Their Formation\n Timeline Unveiled by ALMA, HST, and JWST in NGC 3351: We study young massive clusters (YMCs) in their embedded \"infant\" phase with\n$\\sim$0.1\" ALMA, HST, and JWST observations targeting the central starburst\nring in NGC 3351, a nearby Milky Way analog galaxy. Our new ALMA data reveal 18\nbright and compact (sub-)millimeter continuum sources, of which 11 have\napparent counterparts in JWST images and only 6 have counterparts in HST\nimages. Based on the ALMA continuum and molecular line data, as well as\nancillary measurements for the HST and JWST counterparts, we identify 14\nsources as infant star clusters with high stellar and/or gas masses\n(${\\sim}10^5\\;\\mathrm{M_\\odot}$), small radii (${\\lesssim}\\,5\\;\\mathrm{pc}$),\nlarge escape velocities ($6{-}10\\;\\mathrm{km/s}$), and short free-fall times\n($0.5{-}1\\;\\mathrm{Myr}$). Their multiwavelength properties motivate us to\ndivide them into four categories, likely corresponding to four evolutionary\nstages from starless clumps to exposed HII region-cluster complexes. Leveraging\nage estimates for HST-identified clusters in the same region, we infer an\nevolutionary timeline going from $1{-}2\\;\\mathrm{Myr}$ before cluster formation\nas starless clumps, to $4{-}6\\;\\mathrm{Myr}$ after as exposed HII\nregion-cluster complexes. Finally, we show that the YMCs make up a substantial\nfraction of recent star formation across the ring, exhibit an non-uniform\nazimuthal distribution without a very coherent evolutionary trend along the\nring, and are capable of driving large-scale gas outflows." }, { "anchor": "Variations in the initial mass function in early-type galaxies: A\n critical comparison between dynamical and spectroscopic results: I present a comparison between published dynamical (ATLAS3D) and\nspectroscopic (Conroy & van Dokkum) constraints on the stellar initial mass\nfunction (IMF) in early-type galaxies, using the 34 galaxies in common between\nthe two works. Both studies infer an average IMF mass factor $\\alpha$ (the\nstellar mass relative to a Kroupa-IMF population of similar age and\nmetallicity) greater than unity, i.e. both methods favour an IMF which is\nheavier than that of the Milky Way, on average over the sample. However, on a\ngalaxy-by-galaxy basis, there is no correlation between $\\alpha$ inferred from\nthe two approaches. I investigate how the two estimates of $\\alpha$ are\ncorrelated systematically with the galaxy velocity dispersion, $\\sigma$, and\nwith the Mg/Fe abundance ratio. The spectroscopic method, based on the\nstrengths of metal absorption lines, yields a correlation only with metal\nabundance ratios: at fixed Mg/Fe, there is no residual correlation with\n$\\sigma$. The dynamical method, applied to exactly the same galaxy sample,\nyields the opposite result: the IMF variation correlates only with dynamics,\nwith no residual correlation with Mg/Fe after controlling for $\\sigma$. Hence\nalthough both methods indicate a heavy IMF on average in ellipticals, they lead\nto incompatible results for the systematic trends, when applied to the same set\nof galaxies. The sense of the disagreement could suggest that one (or both) of\nthe methods has not accounted fully for the main confounding factors, i.e.\nelement abundance ratios or dark matter contributions. Alternatively, the poor\nagreement might indicate additional variation in the detailed shape of the IMF,\nbeyond what can currently be inferred from the spectroscopic features.", "positive": "The faint outer regions of the Pegasus Dwarf Irregular galaxy: a much\n larger and undisturbed galaxy: We investigate the spatial extent and structure of the Pegasus dwarf\nirregular galaxy using deep, wide-field, multicolour CCD photometry from the\nSloan Digital Sky Survey (SDSS) and new deep HI observations. We study an area\nof ~0.6 square degrees centred on the Pegasus dwarf that was imaged by SDSS.\nUsing effective filtering in colour-magnitude space we reduce the contamination\nby foreground Galactic field stars and increase significantly the contrast in\nthe outer regions of the Pegasus dwarf. Our extended surface photometry,\nreaches down to a surface brightness magnitude mu_r~32 mag/sq.arcsec. It\nreveals a stellar body with a diameter of ~8 kpc that follows a Sersic surface\nbrightness distribution law, which is composed of a significantly older stellar\npopulation than that observed in the ~2 kpc main body. The galaxy is at least\nfive times more extended than listed in NED. The faint extensions of the galaxy\nare not equally distributed around its circumference; the north-west end is\nmore jagged than the south-east end. We also identified a number of stellar\nconcentrations, possibly stellar associations, arranged in a ring around the\nmain luminous body. New HI observations were collected at the Arecibo\nObservatory as part of the ALFALFA survey. They reveal an HI distribution\nsomewhat elongated in RA and about 0.3 deg. wide, with the region of highest\ncolumn density coincident with the luminous galaxy. The HI rotation curve shows\na solid-body rotation behaviour, with opposite ends differing by 15 km/s. There\nis a stream to lower velocities about 5 arcmin from the centre of the galaxy.\nWe were able to measure ugriz colours in a number of apertures using the SDSS\ndata and compared these with predictions of evolutionary synthesis models.\n(abridged)" }, { "anchor": "The Einasto model for dark matter haloes: Context: The Einasto model has become one of the most popular models for\ndescribing the density profile of dark matter haloes. There have been\nrelatively few comprehensive studies on the dynamical structure of the Einasto\nmodel, mainly because only a limited number of properties can be calculated\nanalytically. Aims: We want to systematically investigate the photometric and\ndynamical structure of the family of Einasto models over the entire model\nparameter space. Methods: We used the SpheCow code to explore the properties of\nthe Einasto model. We systematically investigated how the most important\nproperties change as a function of the Einasto index $n$. We considered both\nisotropic models and radially anisotropic models with an Osipkov-Merritt\norbital structure. Results: We find that all Einasto models with $n<\\tfrac12$\nhave a formal isotropic or Osipkov-Merritt distribution function that is\nnegative in parts of phase space, and hence cannot be supported by such orbital\nstructures. On the other hand, all models with larger values of $n$ can be\nsupported by an isotropic orbital structure, or by an Osipkov-Merritt\nanisotropy, as long as the anisotropy radius is larger than a critical value.\nThis critical anisotropy radius is a decreasing function of $n$, indicating\nthat less centrally concentrated models allow for a larger degree of radial\nanisotropy. Conclusions: Studies of the structure and dynamics of models for\ngalaxies and dark matter haloes should not be restricted to completely\nanalytical models. Numerical codes such as SpheCow can help open up the range\nof models that are systematically investigated. This applies to the Einasto\nmodel discussed here, but also to other proposed models for dark matter haloes,\nincluding different extensions to the Einasto model.", "positive": "Sub-kpc star-formation law in the local luminous infrared galaxy IC 4687\n as seen by ALMA: We analyze the spatially resolved (250 pc scales) and integrated\nstar-formation (SF) law in the local luminous infrared galaxy (LIRG) IC4687.\nThis is one of the first studies of the SF law on a starburst LIRG at these\nsmall spatial scales. We combined new interferometric ALMA CO(2-1) data with\nexisting HST/NICMOS Pa$\\alpha$ narrow-band imaging and VLT/SINFONI near-IR\nintegral field spectroscopy to obtain accurate extinction corrected SF rate\n(SFR) and cold molecular gas surface densities ($\\Sigma_{gas}$ and\n$\\Sigma_{SFR}$). We find that IC4687 forms stars very efficiently with an\naverage depletion time ($t_{dep}$) of 160 Myr for the individual 250 pc\nregions. This is approximately one order of magnitude shorter than the\n$t_{dep}$ of local normal spirals and also shorter than that of main-sequence\nhigh-z objects, even when we use a Galactic $\\alpha_{CO}$ conversion factor.\nThis result suggests a bimodal SF law in the $\\Sigma_{SFR} \\propto\n\\Sigma_{gas}^{N}$ representation. A universal SF law is recovered if we\nnormalize the $\\Sigma_{gas}$ by the global dynamical time. However, at the\nspatial scales studied here, we find that the SF efficiency (or $t_{dep}$) does\nnot depend on the local dynamical time for this object. Therefore, an\nalternative normalization (e.g., free-fall time) should be found if a universal\nSF law exists at these scales." }, { "anchor": "Physical properties and the variability mechanism of the He I outflow in\n NGC 4151: We report on variable helium absorption lines in NGC 4151 observed across six\nepochs of quasi-simultaneous near-infrared and optical data. These observations\ncover the transitions from the metastable 2^3S state at 3889 A and 10830 A, and\nfrom the 2^1S state at 20587 A. This is the first AGN absorption line\nvariability study to include measurements of the 20587 A line. The physical\nproperties of the absorber recorded at the fifth observational epoch are\nrelatively well constrained by the presence of absorption in both the optical\nand near-infrared components, with the 10830 A line likely saturated. The\nobservations suggest variations in this absorber's strength are best explained\nby ionization changes in response to a variable incident continuum.\nPhotoionization simulations constrain the total hydrogen number density of the\nepoch 5 absorber to 7.16000$K show a net asymmetric motion of $\\sim3 km\\,s^{-1}$ in\n$\\langle W\\rangle$ compared to the stars with ${T}_{\\rm eff}<6000$K. And their\nazimuthal velocity increases when $|z|$ increases. This peculiar motion in the\nwarmer stars is likely because they are young and not completely relaxed,\nalthough other reasons, such as the resonance induced by the central rotating\nbar or the spiral structures, and the perturbation of the merging dwarf\ngalaxies, can not be ruled out. The derived velocity dispersions and cross\nterms for the data are approximately consistent with previous studies. We also\nfind that the vertical gradients of $\\sigma_{U}$ and $\\sigma_V$ are larger than\nthat of $\\sigma_W$ . And the vertical gradient of $\\sigma_U$ shows clear\ncorrelation with ${T}_{\\rm eff}$, while the other two do not. Finally, our\nsample shows vertex deviation of about 11$^\\circ$, at $300 < |z| < 500$pc, but\nroughly zero at $100 < |z| < 300$pc.", "positive": "Ultra-deep Ks-band Imaging of the Hubble Frontier Fields: We present an overview of the \"KIFF\" project, which provides ultra-deep\nKs-band imaging of all six of the Hubble Frontier Fields clusters Abell 2744,\nMACS-0416, Abell S1063, Abell 370, MACS-0717 and MACS-1149. All of these fields\nhave recently been observed with large allocations of Directors' Discretionary\nTime with the HST and Spitzer telescopes covering 0.4 < lambda < 1.6 microns\nand 3.6--4.5 microns, respectively. VLT/HAWK-I integrations of the first four\nfields reach 5-sigma limiting depths of Ks~26.0 (AB, point sources) and have\nexcellent image quality (FWHM ~ 0.\"4). Shorter Keck/MOSFIRE integrations of the\nMACS-0717 (MACS-1149) field better observable in the north reach limiting\ndepths Ks=25.5 (25.1) with seeing FWHM ~0.\"4 (0.\"5). In all cases the Ks-band\nmosaics cover the primary cluster and parallel HST/ACS+WFC3 fields. The total\narea of the Ks-band coverage is 490 arcmin^2. The Ks-band at 2.2 microns\ncrucially fills the gap between the reddest HST filter (1.6 micron ~ H-band)\nand the IRAC 3.6 micron passband. While reaching the full depths of the\nspace-based imaging is not currently feasible from the ground, the deep Ks-band\nimages provide important constraints on both the redshifts and the stellar\npopulation properties of galaxies extending well below the characteristic\nstellar mass across most of the age of the universe, down to, and including,\nthe redshifts of the targeted galaxy clusters (z < 0.5)." }, { "anchor": "Improving the open cluster census. II. An all-sky cluster catalogue with\n Gaia DR3: Data from the Gaia satellite are revolutionising our understanding of the\nMilky Way. With every new data release, there is a need to update the census of\nopen clusters. We aim to conduct a blind, all-sky search for open clusters\nusing 729 million sources from Gaia DR3 down to magnitude $G\\sim20$, creating a\nhomogeneous catalogue of clusters including many new objects. We used the\nHierarchical Density-Based Spatial Clustering of Applications with Noise\n(HDBSCAN) algorithm to recover clusters. We validated our clusters using a\nstatistical density test and a Bayesian convolutional neural network for\ncolour-magnitude diagram classification. We inferred basic astrometric\nparameters, ages, extinctions, and distances for the clusters in the catalogue.\nWe recovered 7167 clusters, 2387 of which are candidate new objects and 4782 of\nwhich crossmatch to objects in the literature, including 134 globular clusters.\nA more stringent cut of our catalogue contains 4105 highly reliable clusters,\n739 of which are new. Owing to the scope of our methodology, we are able to\ntentatively suggest that many of the clusters we are unable to detect may not\nbe real, including 1152 clusters from the Milky Way Star Cluster (MWSC)\ncatalogue that should have been detectable in Gaia data. Our cluster membership\nlists include many new members and often include tidal tails. Our catalogue's\ndistribution traces the galactic warp, the spiral arm structure, and the dust\ndistribution of the Milky Way. While much of the content of our catalogue\ncontains bound open and globular clusters, as many as a few thousand of our\nclusters are more compatible with unbound moving groups, which we will classify\nin an upcoming work. We have conducted the largest search for open clusters to\ndate, producing a single homogeneous star cluster catalogue which we make\navailable with this paper.", "positive": "Prediction of galaxy halo masses in SDSS DR7 via a machine learning\n approach: We present a machine learning (ML) approach for the prediction of galaxies'\ndark matter halo masses that achieves an improved performance over conventional\nmethods. We train three ML algorithms (\\texttt{XGBoost}, Random Forests, and\nneural network) to predict halo masses using a set of synthetic galaxy\ncatalogues that are built by populating dark matter haloes in N-body\nsimulations with galaxies, and that match both the clustering and the\njoint-distributions of properties of galaxies in the Sloan Digital Sky Survey\n(SDSS). We explore the correlation of different galaxy- and group-related\nproperties with halo mass, and extract the set of nine features that contribute\nthe most to the prediction of halo mass. We find that mass predictions from the\nML algorithms are more accurate than those from halo abundance matching\n(\\texttt{HAM}) or dynamical mass (\\texttt{DYN}) estimates. Since the danger of\nthis approach is that our training data might not accurately represent the real\nUniverse, we explore the effect of testing the model on synthetic catalogues\nbuilt with different assumptions than the ones used in the training phase. We\ntest a variety of models with different ways of populating dark matter haloes,\nsuch as adding velocity bias for satellite galaxies. We determine that, though\ntraining and testing on different data can lead to systematic errors in\npredicted masses, the ML approach still yields substantially better masses than\neither \\texttt{HAM}or \\texttt{DYN}. Finally, we apply the trained model to a\ngalaxy and group catalogue from the SDSS DR7 and present the resulting halo\nmasses." }, { "anchor": "A physical model for the UV/optical power spectra of AGN: The UV/optical variability of AGN has long been thought to be driven by the\nX-ray illumination of the accretion disk. However, recent multi-wavelength\ncampaigns of nearby Seyfert galaxies seem to challenge this paradigm, with an\napparent discrepancy between observations and the underlying theory. In order\nto further probe the connection between the UV/optical and X-ray variability in\nAGN we developed a physical model to reproduce the UV/optical power spectra\n(PSDs) of AGN assuming the thermal reprocessing of the X-rays in the disk. This\nmodel offers a novel way to probe the innermost regions of AGN. We use our\nmodel to study the variability of NGC 5548 and we infer that the X-ray and\nUV/optical PSDs as well as the interband UV/optical time lags are all well\nreproduced. We also derive constraints on the source physical parameters, such\nas the X-ray corona height and the accretion rate. Our results suggest that\nX-ray disk reprocessing accounts for the full variability properties of this\nAGN, within the considered time scales. Using earlier data of NGC 5548, we also\nshow that our model can reproduce its PSD in different epochs, establishing the\nfeasibility of using PSD modelling to investigate the time evolution of a\nsource.", "positive": "Searching for converging flows of atomic gas onto a molecular cloud: We present new observations of [CII] fine structure line emission from an\nisolated molecular cloud using the upGREAT instrument onboard SOFIA. These data\nare analyzed together with archival CO=1-0 and HI 21 cm emission spectra to\ninvestigate the role of converging atomic gas flows in the formation of\nmolecular clouds. Bright [CII] emission is detected throughout the mapped area\nthat likely originates from photodissociation regions excited by UV radiation\nfields produced by newborn stars within the cloud. Upon spatial averaging of\nthe [CII] spectra, we identify weak [CII] emission within velocity intervals\nwhere the HI 21 cm line is brightest; these are blue-shifted relative to\nvelocities of the CO and bright [CII] emission by 4 km/s. The brightness\ntemperatures, velocity dispersions, and alignment with HI 21 cm velocities\nconnect this [CII] emission component to the cold, neutral atomic gas of the\ninterstellar medium (CNM). We propose that this CNM feature is an accretion\nflow onto the far--side of the existing molecular cloud. The mass infall rate\nis 3.2x10**{-4} Msun/yr. There is no direct evidence of a comparable\nred--shifted component in the [CII] or HI 21 cm spectral lines that would\nindicate the presence of a converging flow." }, { "anchor": "J-NEP: 60-band photometry and photometric redshifts for the James Webb\n Space Telescope North Ecliptic Pole Time-Domain Field: The J-PAS survey will observe ~1/3 of the northern sky with a set of 56\nnarrow-band filters using the dedicated 2.55 m JST telescope at the Javalambre\nAstrophysical Observatory. Prior to the installation of the main camera, in\norder to demonstrate the scientific potential of J-PAS, two small surveys were\nperformed with the single-CCD Pathfinder camera: miniJPAS (~1 deg2 along the\nExtended Groth Strip), and J-NEP (~0.3 deg2 around the JWST North Ecliptic Pole\nTime Domain Field), including all 56 J-PAS filters as well as u, g, r, and i.\nJ-NEP is ~0.5-1.0 magnitudes deeper than miniJPAS, providing photometry for\n24,618 r-band detected sources and photometric redshifts (photo-z) for the\n6,662 sources with r<23.\n In this paper we describe the photometry and photo-z of J-NEP and demonstrate\na new method for the removal of systematic offsets in the photometry based on\nthe median colours of galaxies, dubbed \"galaxy locus recalibration\". This\nmethod does not require spectroscopic observations except in a few reference\npointings and, unlike previous methods, is applicable to the whole J-PAS\nsurvey.\n We use a spectroscopic sample of 787 galaxies to test the photo-z performance\nfor J-NEP and in comparison to miniJPAS. We find that the deeper J-NEP\nobservations result in a factor ~1.5-2 decrease in sigma_NMAD (a robust\nestimate of the standard deviation of the photo-z error) and the outlier rate\nrelative to miniJPAS for r>21.5 sources, but no improvement in brighter ones.\nWe find the same relation between sigma_NMAD and odds in J-NEP and miniJPAS,\nsuggesting sigma_NMAD can be predicted for any set of J-PAS sources from their\nodds distribution alone, with no need for additional spectroscopy to calibrate\nthe relation. We explore the causes for photo-z outliers and find that\ncolour-space degeneracy at low S/N, photometry artifacts, source blending, and\nexotic spectra are the most important factors.", "positive": "New Insights on Ly-alpha and Lyman Continuum Radiative Transfer in the\n Greenest Peas: As some of the only Lyman continuum (LyC) emitters at z~0, Green Pea (GP)\ngalaxies are possible analogs of the sources that reionized the universe. We\npresent HST COS spectra of 13 of the most highly ionized GPs, with [O III]/[O\nII]=6-35, and investigate correlations between Ly-alpha, galaxy properties, and\nlow-ionization UV lines. Galaxies with high [O III]/[O II] have higher H-alpha\nequivalent widths (EWs), and high intrinsic Ly-alpha production may explain the\nprevalence of high Ly-alpha EWs among GPs. While Ly-alpha escape fraction is\nclosely linked to low gas covering fractions, implying a clumpy gas geometry,\nnarrow Ly-alpha velocity peak separation (delta_v,LyA) correlates with the\nionization state, suggesting a density-bounded geometry. We therefore suggest\nthat delta_v,LyA may trace the residual transparency of low-column-density\npathways. Metallicity is associated with both [O III]/[O II] and delta_v,LyA.\nThis trend may result from catastrophic cooling around low-metallicity star\nclusters, which generates a compact geometry of dense clouds within a\nlow-density inter-clump medium. We find that the relative strength of\nlow-ionization UV emission to absorption correlates with Ly-alpha emission\nstrength and is related to Ly-alpha profile shape. However, as expected for\noptically thin objects, the GPs with the lowest delta_v,LyA show both weak\nlow-ionization emission and weak absorption. The strengths of the\nlow-ionization absorption and emission lines in a stacked spectrum do not\ncorrespond to any individual spectrum. Galaxies with high [O III]/[O II]\ncontain a high fraction of LyC emitter candidates, but [O III]/[O II] alone is\nan insufficient diagnostic of LyC escape." }, { "anchor": "Reconstructing the Arches I: Constraining the Initial Conditions: We have performed a series of N-body simulations to model the Arches cluster.\nOur aim is to find the best fitting model for the Arches cluster by comparing\nour simulations with observational data and to constrain the parameters for the\ninitial conditions of the cluster. By neglecting the Galactic potential and\nstellar evolution, we are able to efficiently search through a large parameter\nspace to determine e.g. the IMF, size, and mass of the cluster. We find, that\nthe cluster's observed present-day mass function can be well explained with an\ninitial Salpeter IMF. The lower mass-limit of the IMF cannot be well\nconstrained from our models. In our best models, the total mass and the virial\nradius of the cluster are initially (5.1 +/- 0.8) 10^4 Msun and 0.76 +/- 0.12\npc, respectively. The concentration parameter of the initial King model is w0 =\n3-5.", "positive": "NuSTAR observations of heavily obscured Swift/BAT AGN: constraints on\n the Compton-thick AGN fraction: The all-sky hard X-ray survey performed by Swift/BAT allowed the detection of\nmany heavily obscured Compton-thick AGN. In our previous work, we have\nidentified more than 50 candidate Compton-thick AGN in the local Universe,\ncorresponding to an observed fraction of about 7% of the total AGN population.\nThis number can be converted to the intrinsic Compton-thick AGN number density,\nonly if we know the form of the Compton-thick AGN spectrum, that is the energy\nof their absorption turnover, photon-index and its cut-off energy at high\nenergies, as well as the strength of the reflection component on the matter\nsurrounding the nucleus. In order to constrain their number density, we analyse\nthe spectra of 19 Compton-thick AGN which have been detected with Swift/BAT and\nhave been subsequently observed with NuSTAR in the 3-80 keV band. We analyse\ntheir X-ray spectra using the MYTORUS models of Murphy and Yaqoob which\nproperly take into account the Compton scattering effects. These are combined\nwith physically motivated Comptonisation models which accurately describe the\nprimary coronal X-ray emission. We derive absorbing column densities which are\nconsistent with those derived by the previous Swift/BAT analyses. We estimate\nthe coronal temperatures to be roughly between 25 and 80 keV corresponding to\nhigh energy cut-offs roughly between 75 and 250 keV. We find that the majority\nof our AGN lacks a strong reflection component in the 20-40 keV band placing\ntighter constraints on the intrinsic Compton-thick AGN fraction. Combining\nthese results with our X-ray background synthesis models, we estimate a\nCompton-thick AGN fraction in the local Universe of ~20 +/-3 % relative to the\ntype-II AGN population." }, { "anchor": "Debris discs around nearby Solar analogues: An unbiased search for debris discs around nearby Sun-like stars is reported.\nThirteen G-dwarfs at 12-15 parsecs distance were searched at 850 $\\umu$m\nwavelength, and a disc is confirmed around HD 30495. The estimated dust mass is\n0.008 M$_{\\oplus}$ with a net limit $\\la 0.0025$ M$_{\\oplus}$ for the average\ndisc of the other stars. The results suggest there is not a large missed\npopulation of substantial cold discs around Sun-like stars -- HD 30495 is a\nbright rather than unusually cool disc, and may belong to a few hundred Myr-old\npopulation of greater dust luminosity. The far-infared and millimetre survey\ndata for Sun-like stars are well fitted by either steady state or stirred\nmodels, provided that typical comet belts are comparable in size to that in the\nSolar System.", "positive": "Dissecting the molecular structure of the Orion B cloud: Insight from\n Principal Component Analysis: Context. The combination of wideband receivers and spectrometers currently\navailable in (sub-)millimeter observatories deliver wide- field hyperspectral\nimaging of the interstellar medium. Tens of spectral lines can be observed over\ndegree wide fields in about fifty hours. This wealth of data calls for\nrestating the physical questions about the interstellar medium in statistical\nterms. Aims. We aim at gaining information on the physical structure of the\ninterstellar medium from a statistical analysis of many lines from different\nspecies over a large field of view, without requiring detailed radiative\ntransfer or astrochemical modeling. Methods. We coupled a nonlinear rescaling\nof the data with one of the simplest multivariate analysis methods, namely the\nPrincipal Component Analysis, to decompose the observed signal into components\nthat we interpret first qualitatively and then quantitatively based on our deep\nknowledge of the observed region and of the astrochemistry at play. Results. We\nidentify 3 principal components, linear compositions of line brightness\ntemperatures, that are correlated at various levels with the column density,\nthe volume density and the UV radiation field. Conclusions. When sampling a\nsufficiently diverse mixture of physical parameters, it is possible to\ndecompose the molecular emission in order to gain physical insight on the\nobserved interstellar medium. This opens a new avenue for future studies of the\ninterstellar medium." }, { "anchor": "Spatial Variations in Galactic H I Structure on AU-Scales Toward 3C 147\n Observed with the Very Long Baseline Array: This paper reports dual-epoch, Very Long Baseline Array observations of H I\nabsorption toward 3C 147. One of these epochs (2005) represents new\nobservations while one (1998) represents the reprocessing of previous\nobservations to obtain higher signal-to-noise results. Significant H I opacity\nand column density variations, both spatially and temporally, are observed with\ntypical variations at the level of \\Delta\\tau ~ 0.20 and in some cases as large\nas \\Delta\\tau ~ 0.70, corresponding to column density fluctuations of order 5 x\n10^{19} cm^{-2} for an assumed 50 K spin temperature. The typical angular scale\nis 15 mas; while the distance to the absorbing gas is highly uncertain, the\nequivalent linear scale is likely to be about 10 AU. Approximately 10% of the\nface of the source is covered by these opacity variations, probably implying a\nvolume filling factor for the small-scale absorbing gas of no more than about\n1%. Comparing our results with earlier results toward 3C 138 (Brogan et al.),\nwe find numerous similarities, and we conclude that small-scale absorbing gas\nis a ubiquitous phenomenon, albeit with a low probability of intercept on any\ngiven line of sight. Further, we compare the volumes sampled by the line of\nsight through the Galaxy between our two epochs and conclude that, on the basis\nof the motion of the Sun alone, these two volumes are likely to be\nsubstantially different. In order to place more significant constraints on the\nvarious models for the origin of these small-scale structures, more frequent\nsampling is required in any future observations.", "positive": "Spectroscopic confirmation of a gravitationally lensed Lyman break\n galaxy at z$_{[CII]}$ = 6.827 using NOEMA: We present the spectroscopic confirmation of the brightest known\ngravitationally lensed Lyman break galaxy in the Epoch of Reionisation,\nA1703-zD1, through the detection of [C II] at a redshift of z = 6.8269 +/-\n0.0004. This source was selected behind the strong lensing cluster Abell 1703,\nwith an intrinsic L$_{UV}$ ~ L$^*$$_{z=7}$ luminosity and a very blue\nSpitzer/IRAC [3.6]-[4.5] colour, implying high equivalent width line emission\nof [O III]+H$\\beta$. [C II] is reliably detected at 6.1$\\sigma$ co-spatial with\nthe rest-frame UV counterpart, showing similar spatial extent. Correcting for\nthe lensing magnification, the [C II] luminosity in A1703-zD1 is broadly\nconsistent with the local L$_{[CII]}$ - SFR relation. We find a clear velocity\ngradient of 103 +/- 22 km/s across the source which possibly indicates rotation\nor an ongoing merger. We furthermore present spectral scans with no detected [C\nII] above 4.6$\\sigma$ in two unlensed Lyman break galaxies in the EGS-CANDELS\nfield at z ~ 6.6 - 6.9. This is the first time that NOEMA has been successfully\nused to observe [C II] in a 'normal' star-forming galaxy at z > 6, and our\nresults demonstrate its capability to complement ALMA in confirming galaxies in\nthe Epoch of Reionisation." }, { "anchor": "A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE):\n A First Look at the Rest-frame Optical Spectra of $z > 6.5$ Quasars Using\n JWST: Studies of rest-frame optical emission in quasars at $z>6$ have historically\nbeen limited by the wavelengths accessible by ground-based telescopes. The\nJames Webb Space Telescope (JWST) now offers the opportunity to probe this\nemission deep into the reionization epoch. We report the observations of eight\nquasars at $z>6.5$ using the JWST/NIRCam Wide Field Slitless Spectroscopy, as a\npart of the ''A SPectroscopic survey of biased halos In the Reionization Era\n(ASPIRE)\" program. Our JWST spectra cover the quasars' emission between rest\nframe $\\sim$ 4100 and 5100 \\r{A}. The profiles of these quasars' broad H$\\beta$\nemission lines span a FWHM from 3000 to 6000 $\\rm{km~s^{-1}}$. The\nH$\\beta$-based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion\nsolar masses, are generally consistent with their MgII-based BH masses. The new\nmeasurements based on the more reliable H$\\beta$ tracer thus confirm the\nexistence of billion solar-mass BHs in the reionization epoch. In the observed\n[OIII] $\\lambda\\lambda$4960,5008 doublets of these luminous quasars, broad\ncomponents are more common than narrow core components\n($\\le~1200~\\rm{km~s^{-1}}$), and only one quasar shows stronger narrow\ncomponents than broad. Two quasars exhibit significantly broad and blueshifted\n[OIII] emission, thought to trace galactic-scale outflows, with median\nvelocities of $-610~\\rm{km~s^{-1}}$ and $-1430~\\rm{km~s^{-1}}$ relative to the\n[CII] $158\\,\\mu$m line. All eight quasars show strong optical FeII emission,\nand follow the Eigenvector 1 relations defined by low-redshift quasars. The\nentire ASPIRE program will eventually cover 25 quasars and provide a\nstatistical sample for the studies of the BHs and quasar spectral properties.", "positive": "The breakBRD Breakdown: Using IllustrisTNG to Track the Quenching of an\n Observationally-Motivated Sample of Centrally Star-Forming Galaxies: The observed breakBRD (\"break bulges in red disks\") galaxies are a nearby\nsample of face-on disk galaxies with particularly centrally concentrated star\nformation: they have red disks but recent star formation in their centers as\nmeasured by the D$_n$4000 spectral index (Tuttle & Tonnesen 2020). In this\npaper, we search for breakBRD analogues in the IllustrisTNG simulation and\ndescribe their history and future. We find that a small fraction (${\\sim}4\\%$\nat $z=0$; ${\\sim}1\\%$ at $z=0.5$) of galaxies fulfill the breakBRD criteria, in\nagreement with observations. In comparison with the mass-weighted parent\nIllustrisTNG sample, these galaxies tend to consist of a higher fraction of\nsatellite and splashback galaxies. However, the central, non-splashback\nbreakBRD galaxies show similar environments, black hole masses, and merger\nrates, indicating that there is not a single formation trigger for inner star\nformation and outer quenching. We determine that breakBRD analogue galaxies as\na whole are in the process of quenching. The breakBRD state - with its highly\ncentrally concentrated star formation - is uncommon in the history of either\ncurrently quiescent or star-forming galaxies; however, approximately 10% of\n$10^{10} < M_\\ast/M_{\\odot} < 10^{11}$ quiescent galaxies at $z=0$ have\nexperienced SFR concentrations comparable to those of the breakBRDs in their\npast. Additionally, the breakBRD state is short-lived, lasting a few hundred\nMyr up to ${\\sim}2$ Gyr. The observed breakBRD galaxies may therefore be a\nunique sample of outside-in quenching galaxies." }, { "anchor": "Strong excess Faraday rotation on the Inside of the Sagittarius spiral\n arm: We present first results for Faraday rotation of compact polarized sources (1\nto 2 GHz continuum) in The HI/OH/Recombination line (THOR) survey of the inner\nGalaxy. In the Galactic longitude range 39 degr < l < 52 degr, we find rotation\nmeasures in the range -310 rad/m2 < RM < +4219 rad/m2, with the highest values\nconcentrated within a degree of l = 48 degrees at the Sagittarius arm tangent.\nMost of the high RMs arise in diffuse plasma, along lines of sight that do not\nintersect HII regions. For l > 49 degr, RM drops off rapidly, while at l < 47\ndegr, the mean RM is higher with a larger standard deviation than at l > 49\ndegr. We attribute the RM structure to the compressed diffuse Warm Ionized\nMedium in the spiral arm, upstream of the major star formation regions. The\nSagittarius arm acts as a significant Faraday screen inside the Galaxy. This\nhas implications for models of the Galactic magnetic field and the expected\namount of Faraday rotation of Fast Radio Bursts from their host galaxies. We\nemphasize the importance of sensitivity to high Faraday depth in future\npolarization surveys.", "positive": "A NuSTAR Survey of Nearby Ultraluminous Infrared Galaxies: We present a NuSTAR, Chandra, and XMM--Newton survey of nine of the nearest\nultraluminous infrared galaxies (ULIRGs). The unprecedented sensitivity of\nNuSTAR at energies above 10 keV enables spectral modeling with far better\nprecision than was previously possible. Six of the nine sources observed were\ndetected sufficiently well by NuSTAR to model in detail their broadband X-ray\nspectra, and recover the levels of obscuration and intrinsic X-ray\nluminosities. Only one source (IRAS 13120--5453) has a spectrum consistent with\na Compton--thick AGN, but we cannot rule out that a second source (Arp 220)\nharbors an extremely highly obscured AGN as well. Variability in column density\n(reduction by a factor of a few compared to older observations) is seen in IRAS\n05189--2524 and Mrk 273, altering the classification of these border-line\nsources from Compton-thick to Compton-thin. The ULIRGs in our sample have\nsurprisingly low observed fluxes in high energy (>10 keV) X-rays, especially\ncompared to their bolometric luminosities. They have lower ratios of unabsorbed\n2--10 keV to bolometric luminosity, and unabsorbed 2--10 keV to mid-IR [O IV]\nline luminosity than do Seyfert 1 galaxies. We identify IRAS 08572+3915 as\nanother candidate intrinsically X-ray weak source, similar to Mrk 231. We\nspeculate that the X-ray weakness of IRAS 08572+3915 is related to its powerful\noutflow observed at other wavelengths." }, { "anchor": "Lupus I Observations from the 2010 Flight of the Balloon-borne Large\n Aperture Submillimeter Telescope for Polarimetry: The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry\n(BLASTPol) was created by adding polarimetric capability to the BLAST\nexperiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's\n1.8 m primary and its Herschel/SPIRE heritage focal plane that allows\nsimultaneous observation at 250, 350, and 500 {\\mu}m. We flew BLASTPol in 2010\nand again in 2012. Both were long duration Antarctic flights. Here we present\npolarimetry of the nearby filamentary dark cloud Lupus I obtained during the\n2010 flight. Despite limitations imposed by the effects of a damaged optical\ncomponent, we were able to clearly detect submillimeter polarization on degree\nscales. We compare the resulting BLASTPol magnetic field map with a similar map\nmade via optical polarimetry (The optical data were published in 1998 by J.\nRizzo and collaborators.). The two maps partially overlap and are reasonably\nconsistent with one another. We compare these magnetic field maps to the\norientations of filaments in Lupus I, and we find that the dominant filament in\nthe cloud is approximately perpendicular to the large-scale field, while\nsecondary filaments appear to run parallel to the magnetic fields in their\nvicinities. This is similar to what is observed in Serpens South via near-IR\npolarimetry, and consistent with what is seen in MHD simulations by F. Nakamura\nand Z. Li.", "positive": "The dust mass function from z~0 to z~2: We derive for the first time the dust mass function (DMF) in a wide redshift\nrange, from z~0.2 up to z~2.5. In order to trace the dust emission, we start\nfrom a far-IR (160-um) Herschel selected catalogue in the COSMOS field. We\nestimate the dust masses by fitting the far-IR data (lam_rest>50um) with a\nmodified black body function and we present a detailed analysis to take into\naccount the incompleteness in dust masses from a far-IR perspective. By\nparametrizing the observed DMF with a Schechter function in the redshift range\n0.10.6$)\nbeing mostly satellites. The fraction of red LMC-mass dwarfs is 15% for\ncentrals, and for satellites this fraction increases rapidly with host mass:\nfrom 10% for satellites of Milky Way (MW)-mass haloes to nearly 90% for\nsatellites of groups and clusters. The quenching timescale, defined as the time\nafter infall when half of the satellites have acquired red colours, decreases\nwith host mass from ${>}5$ Gyrs for MW-mass hosts to $2.5$ Gyrs for cluster\nmass hosts. The satellites of MW-mass haloes have higher star formation rates\nand bluer colours than field galaxies. This is due to enhanced star formation\ntriggered by gas compression shortly after accretion. Both the LMC and M33 have\nenhanced recent star formation that could be a manifestation of this process.\nAfter infall into their MW-mass hosts, the $g-r$ colours of LMC-mass dwarfs\nbecome bluer for the first 2 Gyrs, after which they rapidly redden. LMC-mass\ndwarfs fell into their MW-mass hosts only relatively recently, with more than\nhalf having an infall time of less than 3.5 Gyrs.", "positive": "Post-Starburst Properties of Post-Merger Galaxies: Post-starburst galaxies (PSBs) are transition galaxies showing evidence of\nrecent rapid star formation quenching. To understand the role of galaxy mergers\nin triggering quenching, we investigate the incidence of PSBs and resolved PSB\nproperties in post-merger galaxies using both SDSS single-fiber spectra and\nMaNGA resolved IFU spectra. We find post-mergers have a PSB excess of 10 - 20\ntimes that relative to their control galaxies using single-fiber PSB\ndiagnostics. A similar excess of ~ 19 times is also found in the fraction of\ncentral (C)PSBs and ring-like (R)PSBs in post-mergers using the resolved PSB\ndiagnostic. However, 60% of the CPSBs + RPSBs in both post-mergers and control\ngalaxies are missed by the single-fiber data. By visually inspecting the\nresolved PSB distribution, we find that the fraction of outside-in quenching is\n7 times higher than inside-out quenching in PSBs in post-mergers while PSBs in\ncontrol galaxies do not show large differences in these quenching directions.\nIn addition, we find a marginal deficit of HI gas in PSBs relative to non-PSBs\nin post-mergers using the MaNGA-HI data. The excesses of PSBs in post-mergers\nsuggest that mergers play an important role in triggering quenching. Resolved\nIFU spectra are important to recover the PSBs missed by single-fiber spectra.\nThe excess of outside-in quenching relative to inside-out quenching in\npost-mergers suggests that AGN are not the dominant quenching mechanism in\nthese galaxies, but that processes from the disk (gas inflows/consumption and\nstellar feedback) play a more important role." }, { "anchor": "Unravelling the structure of magnetised molecular clouds with\n SILCC-Zoom: sheets, filaments and fragmentation: To what extent magnetic fields affect how molecular clouds (MCs) fragment and\ncreate dense structures is an open question. We present a numerical study of\ncloud fragmentation using the SILCC-Zoom simulations. These simulations follow\nthe self-consistent formation of MCs in a few hundred parsec sized region of a\nstratified galactic disc; and include magnetic fields, self-gravity,\nsupernova-driven turbulence, as well as a non-equilibrium chemical network. To\ndiscern the role of magnetic fields in the evolution of MCs, we study seven\nsimulated clouds, five with magnetic fields, and two without, with a maximum\nresolution of 0.1 parsec. Using a dendrogram we identify hierarchical\nstructures which form within the clouds. Overall, the magnetised clouds have\nmore mass in a diffuse envelope with a number density between 1-100 cm$^{-3}$.\nWe find that six out of seven clouds are sheet-like on the largest scales, as\nalso found in recent observations, and with filamentary structures embedded\nwithin, consistent with the bubble-driven MC formation mechanism. Hydrodynamic\nsimulations tend to produce more sheet-like structures also on smaller scales,\nwhile the presence of magnetic fields promotes filament formation. Analysing\ncloud energetics, we find that magnetic fields are dynamically important for\nless dense, mostly but not exclusively atomic structures (typically up to $\\sim\n100 - 1000$~cm$^{-3}$), while the denser, potentially star-forming structures\nare energetically dominated by self-gravity and turbulence. In addition, we\ncompute the magnetic surface term and demonstrate that it is generally\nconfining, and some atomic structures are even magnetically held together. In\ngeneral, magnetic fields delay the cloud evolution and fragmentation by $\\sim$\n1 Myr.", "positive": "Structural Parameters of Star Clusters: Stochastic Effects: Stochasticity of bright stars introduces uncertainty and bias into derived\nstructural parameters of star clusters. We have simulated a grid of cluster\n$V$-band images, observed with Subaru Suprime-Cam with age, mass, and size\nrepresenting a cluster population in the M31 galaxy and derived their\nstructural parameters by fitting King model to the surface brightness\ndistribution. We have found that clusters less massive than $10^4 M_\\odot$ show\nsignificant uncertainty in their core and tidal radii for all ages, while\nclusters younger than 10 Myr have their sizes systematically underestimated for\nall masses. This emphasizes the importance of stochastic simulations to asses\nthe true uncertainty of structural parameters in studies of semi-resolved and\nunresolved clusters." }, { "anchor": "A New Method for the Assessment of Age and Age-Spread of Pre-Main\n Sequence Stars in Young Stellar Associations of the Magellanic Clouds: We present a new method for the evaluation of the age and age-spread among\npre-main-sequence (PMS) stars in star-forming regions in the Magellanic Clouds,\naccounting simultaneously for photometric errors, unresolved binarity,\ndifferential extinction, stellar variability, accretion and crowding. The\napplication of the method is performed with the statistical construction of\nsynthetic color-magnitude diagrams using PMS evolutionary models. We convert\neach isochrone into 2D probability distributions of artificial PMS stars in the\nCMD by applying the aforementioned biases that dislocate these stars from their\noriginal CMD positions. A maximum-likelihood technique is then applied to\nderive the probability for each observed star to have a certain age, as well as\nthe best age for the entire cluster. We apply our method to the photometric\ncatalog of ~2000 PMS stars in the young association LH 95 in the LMC, based on\nthe deepest HST/ACS imaging ever performed toward this galaxy, with a detection\nlimit of V~28, corresponding to M~0.2 Msun. Our treatment shows that the age\ndetermination is very sensitive to the considered grid of evolutionary models\nand the assumed binary fraction. The age of LH 95 is found to vary from 2.8 Myr\nto 4.4 Myr, depending on these factors. Our analysis allows us to disentangle a\nreal age-spread from the apparent CMD-broadening caused by the physical and\nobservational biases. We find that LH 95 hosts an age-spread well represented\nby a gaussian distribution with a FWHM of the order of 2.8 Myr to 4.2 Myr\ndepending on the model and binary fraction. We detect a dependence of the\naverage age of the system with stellar mass. This dependence does not appear to\nhave any physical meaning, being rather due to imperfections of the PMS\nevolutionary models, which tend to predict lower ages for the intermediate\nmasses, and higher ages for low-mass stars.", "positive": "The EDGE-CALIFA Survey: Using Optical Extinction to Probe the\n Spatially-Resolved Distribution of Gas in Nearby Galaxies: We present an empirical relation between the cold gas surface density\n($\\Sigma_{\\rm gas}$) and the optical extinction (${\\rm A_V}$) in a sample of\n103 galaxies from the Extragalactic Database for Galaxy Evolution (EDGE)\nsurvey. This survey provides CARMA interferometric CO observations for 126\ngalaxies included in the Calar Alto Legacy Integral Field Area (CALIFA) survey.\nThe matched, spatially resolved nature of these data sets allows us to derive\nthe $\\Sigma_{\\rm gas}$-${\\rm A_V}$ relation on global, radial, and kpc (spaxel)\nscales. We determine ${\\rm A_V}$ from the Balmer decrement\n(H$\\alpha$/H$\\beta$). We find that the best fit for this relation is\n$\\Sigma_{\\rm gas} ({\\rm M_\\odot pc^{-2}})\\sim~26~\\times~ {\\rm A_V}({\\rm mag})$,\nand that it does not depend on the spatial scale used for the fit. However, the\nscatter in the fits increases as we probe smaller spatial scales, reflecting\nthe complex relative spatial distributions of stars, gas, and dust. We\ninvestigate the $\\Sigma_{\\rm gas}$/ ${\\rm A_V}$ ratio on radial and spaxel\nscales as a function of ${\\rm EW(H\\alpha)}$. We find that at larger values of\n${\\rm EW(H\\alpha)}$ (i.e., actively star-forming regions) this ratio tend to\nconverge to the value expected for dust-star mixed geometries ($\\sim$ 30\n$\\mathrm{M_{\\odot} \\,pc^{-2}\\,mag^{-1}}$). On radial scales, we do not find a\nsignificant relation between the $\\Sigma_{\\rm gas}$/${\\rm A_V}$ ratio and the\nionized gas metallicity. We contrast our estimates of $\\Sigma_{\\rm gas}$ using\n${\\rm A_V}$ with compilations in the literature of the gas fraction on global\nand radial scales as well as with well known scaling relations such as the\nradial star-formation law and the $\\Sigma_{\\rm gas}$-$\\Sigma_*$ relation. These\ntests show that optical extinction is a reliable proxy for estimating\n$\\Sigma_{\\rm gas}$ in the absence of direct sub/millimeter observations of the\ncold gas." }, { "anchor": "Paradigms and Scenarios for the Dark Matter Phenomenon: Well known scaling laws among the structural properties of the dark and the\nluminous matter in disc systems are too complex to be arisen by two inert\ncomponents that just share the same gravitational field. This brings us to\ncritically focus on the 30 year old paradigm, that, resting on a priori\nknowledge of the nature of dark matter (DM), has led us to a restricted number\nof scenarios, especially favouring the collisionless $\\Lambda$Cold Dark Matter\none. Motivated by such observational evidence, we propose to resolve the dark\nmatter mystery by following a new paradigm: the nature of DM must be\nguessed/derived by deeply analyzing the properties of the dark and luminous\nmass distribution at galactic scales. The immediate application of this\nparadigm leads us to the existence of a direct interaction between dark and\nStandard Model particles which has finely shaped the inner regions of galaxies.", "positive": "Gravitational instability of filamentary molecular clouds, including\n ambipolar diffusion: The gravitational instability of a filamentary molecular cloud in non-ideal\nmagnetohydrodynamics is investigated. The filament is assumed to be in\nhydrostatic equilibrium. We add the effect of ambipolar diffusion to the\nfilament which is threaded by an initial uniform axial magnetic field along its\naxis. We write down the fluid equations in cylindrical coordinates and perform\nlinear perturbation analysis. We integrate the resultant differential equations\nand then derive the numerical dispersion relation. We find that, a more\nefficient ambipolar diffusion leads to an enhancement of the growth of the most\nunstable mode, and to increase of the fragmentation scale of the filament." }, { "anchor": "Exploring the nature and synchronicity of early cluster formation in the\n Large Magellanic Cloud: III. Horizontal Branch Morphology: We leverage new high-quality data from Hubble Space Telescope program\nGO-14164 to explore the variation in horizontal branch morphology among\nglobular clusters in the Large Magellanic Cloud (LMC). Our new observations\nlead to photometry with a precision commensurate with that available for the\nGalactic globular cluster population. Our analysis indicates that, once\nmetallicity is accounted for, clusters in the LMC largely share similar\nhorizontal branch morphologies regardless of their location within the system.\nFurthermore, the LMC clusters possess, on average, slightly redder morphologies\nthan most of the inner halo Galactic population; we find, instead, that their\ncharacteristics tend to be more similar to those exhibited by clusters in the\nouter Galactic halo. Our results are consistent with previous studies showing a\ncorrelation between horizontal branch morphology and age.", "positive": "Missing Stellar Mass in SED Fitting: Spatially Unresolved Photometry can\n Underestimate Galaxy Masses: We fit model spectral energy distributions to each pixel in 67 nearby\n(=0.0057) galaxies using broadband photometry from the Sloan Digital Sky\nSurvey and GALEX. For each galaxy, we compare the stellar mass derived by\nsumming the mass of each pixel to that found from fitting the entire galaxy\ntreated as an unresolved point source. We find that, while the pixel-by-pixel\nand unresolved masses of galaxies with low specific star formation rates (such\nas ellipticals and lenticulars) are in rough agreement, the unresolved mass\nestimate for star-forming galaxies is systematically lower then the measurement\nfrom spatially-resolved photometry. The discrepancy is strongly correlated with\nsSFR, with the highest sSFRs in our sample having masses underestimated by 25%\n(0.12 dex) when treated as point sources. We found a simple relation to\nstatistically correct mass estimates derived from unresolved broad-band SED\nfitting to the resolved mass estimates: m_{resolved} =\nm_{unresolved}/(-0.057log(sSFR) + 0.34) where sSFR is in units of yr^{-1}. We\nstudy the effect of varying spatial resolution by degrading the image\nresolution of the largest images and find a sharp decrease in the\npixel-by-pixel mass estimate at a physical scale of approximately 3 kpc, which\nis comparable to spiral arm widths. The effects we observe are consistent with\nthe \"outshining\" idea which posits that the youngest stellar populations mask\nmore massive, older -- and thus fainter -- stellar populations. Although the\npresence of strong dust lanes can also lead to a drastic difference between\nresolved and unresolved mass estimates (up to 45% or 0.3 dex) for any\nindividual galaxy, we found that resolving dust does not affect mass estimates\non average. The strong correlation between mass discrepancy and sSFR is thus\nmost likely due to the outshining systematic bias." }, { "anchor": "A Markov model for non-lognormal density distributions in compressive\n isothermal turbulence: Compressive isothermal turbulence is known to have a near lognormal density\nprobability distribution function (PDF) with a width that scales with the sonic\nMach number and nature of the turbulent driving (solenoidal vs compressive).\nHowever, the physical processes that mold the extreme high and low density\nstructures in a turbulent medium can be different, with the densest structures\nbeing composed of strong shocks that evolve on shorter timescales than the low\ndensity fluid. The density PDF in a turbulent medium exhibits deviations from\nlognormal due to shocks, that increases with the sonic Mach number, which is\noften ignored in analytic models for turbulence and star formation. We develop\na simple model for turbulence by treating it as a continuous Markov process,\nwhich explains both the density PDF and the transient timescales of structures\nas a function of density, using a framework developed in n Scannapieco &\nSafarzadeh (2018). Our analytic model depends on only a single parameter, the\neffective compressive sonic Mach number, and successfully describes the\nnon-lognormal behavior seen in both 1D and 3D simulations of supersonic and\nsubsonic compressive isothermal turbulence. The model quantifies the\nnon-lognormal distribution of density structures in turbulent environments, and\nhas application to star forming molecular clouds and star formation\nefficiencies.", "positive": "The Role of Host Galaxy for the Environmental Dependence of Active\n Nuclei in Local Galaxies: We discuss the environment of local hard X-ray selected active galaxies, with\nreference to two independent group catalogues. We find that the fraction of\nthese AGN in S0 host galaxies decreases strongly as a function of galaxy group\nsize (halo mass) - which contrasts with the increasing fraction of galaxies of\nS0 type in denser environments. However, there is no evidence for an\nenvironmental dependence of AGN in spiral galaxies. Because most AGN are found\nin spiral galaxies, this dilutes the signature of environmental dependence for\nthe population as a whole. We argue that the differing results for AGN in\ndisk-dominated and bulge-dominated galaxies is related to the source of the gas\nfuelling the AGN, and so may also impact the luminosity function, duty cycle,\nand obscuration. We find that there is a significant difference in the\nluminosity function for AGN in spiral and S0 galaxies, and tentative evidence\nfor some difference in the fraction of obscured AGN." }, { "anchor": "Hydrodynamical Simulations of Nuclear Rings in Barred Galaxies: Dust lanes, nuclear rings, and nuclear spirals are typical gas structures in\nthe inner region of barred galaxies. Their shapes and properties are linked to\nthe physical parameters of the host galaxy. We use high-resolution\nhydrodynamical simulations to study 2D gas flows in simple barred galaxy\nmodels. The nuclear rings formed in our simulations can be divided into two\ngroups: one group is nearly round and the other is highly elongated. We find\nthat roundish rings may not form when the bar pattern speed is too high or the\nbulge central density is too low. We also study the periodic orbits in our\ngalaxy models, and find that the concept of inner Lindblad resonance (ILR) may\nbe generalized by the extent of $x_2$ orbits. All roundish nuclear rings in our\nsimulations settle in the range of $x_2$ orbits (or ILRs). However, knowing the\nresonances is insufficient to pin down the exact location of these nuclear\nrings. We suggest that the backbone of round nuclear rings is the $x_2$ orbital\nfamily, i.e. round nuclear rings are allowed only in the radial range of $x_2$\norbits. A round nuclear ring forms exactly at the radius where the residual\nangular momentum of infalling gas balances the centrifugal force, which can be\ndescribed by a parameter $f_{\\rm ring}$ measured from the rotation curve. The\ngravitational torque on gas in high pattern speed models is larger, leading to\na smaller ring size than in the low pattern speed models. Our result may have\nimportant implications for using nuclear rings to measure the parameters of\nreal barred galaxies with 2D gas kinematics.", "positive": "Lyman-alpha Absorbers and the Coma Cluster: The spatial and kinematic distribution of warm gas in and around the Coma\nCluster is presented through observations of Lyman-alpha absorbers using\nbackground QSOs. Updates to the Lyman-alpha absorber distribution found in Yoon\net al. (2012) for the Virgo Cluster are also presented. At 0.2-2.0 R_vir of\nComa we identify 14 Lyman-alpha absorbers (N_HI = 10^{12.8-15.9} cm^-2) towards\n5 sightlines and no Lyman-alpha absorbers along 3 sightlines within\n3\\sigmav_coma. For both Coma and Virgo, most Lyman-alpha absorbers are found\noutside the virial radius or beyond 1\\sigmav consistent with them largely\nrepresenting the infalling intergalactic medium. The few exceptions in the\ncentral regions can be associated with galaxies. The Lyman-alpha absorbers\navoid the hot ICM, consistent with the infalling gas being shock-heated within\nthe cluster. The massive dark matter halos of clusters do not show the\nincreasing column density with decreasing impact parameter relationship found\nfor the smaller mass galaxy halos. In addition, while the covering fraction\nwithin R_vir is lower for clusters than galaxies, beyond R_vir the covering\nfraction is somewhat higher for clusters. The velocity dispersion of the\nabsorbers compared to the galaxies is higher for Coma, consistent with the\nabsorbers tracing additional turbulent gas motions in the cluster outskirts.\nThe results are overall consistent with cosmological simulations, with the\ncovering fraction being high in the observations standing out as the primary\ndiscrepancy." }, { "anchor": "A search for extended radio emission from selected compact galaxy groups: Context. Studies on compact galaxy groups have led to the conclusion that a\nplenitude of phenomena take place in between galaxies that form them. However,\nradio data on these objects are extremely scarce and not much is known\nconcerning the existence and role of the magnetic field in intergalactic space.\nAims. We aim to study a small sample of galaxy groups that look promising as\npossible sources of intergalactic magnetic fields; for example data from radio\nsurveys suggest that most of the radio emission is due to extended, diffuse\nstructures in and out of the galaxies. Methods. We used the Effelsberg 100 m\nradio telescope at 4.85 GHz and NRAO VLA Sky Survey (NVSS) data at 1.40 GHz.\nAfter subtraction of compact sources we analysed the maps searching for\ndiffuse, intergalactic radio emission. Spectral index and magnetic field\nproperties were derived. Results. Intergalactic magnetic fields exist in groups\nHCG 15 and HCG 60, whereas there are no signs of them in HCG 68. There are also\nhints of an intergalactic bridge in HCG 44 at 4.85 GHz. Conclusions.\nIntergalactic magnetic fields exist in galaxy groups and their energy density\nmay be comparable to the thermal (X-ray) density, suggesting an important role\nof the magnetic field in the intra-group medium, wherever it is detected.", "positive": "Detection of Interstellar C_2 and C_3 in the Small Magellanic Cloud: We report the detection of absorption from interstellar C_2 and C_3 toward\nthe moderately reddened star Sk 143, located in the near 'wing' region of the\nSMC, in optical spectra obtained with the ESO VLT/UVES. These detections of C_2\n(rotational levels J=0-8) and C_3 (J=0-12) absorption in the SMC are the first\nbeyond our Galaxy. The total abundances of C_2 and C_3 (relative to H_2) are\nsimilar to those found in diffuse Galactic molecular clouds -- as previously\nfound for CH and CN -- despite the significantly lower average metallicity of\nthe SMC. Analysis of the rotational excitation of C_2 yields an estimated\nkinetic temperature T_k ~ 25 K and a moderately high total hydrogen density n_H\n~ 870 cm^-3 -- compared to the T_01 ~ 45 K and n_H ~ 85-300 cm^-3 obtained from\nH_2. The populations of the lower rotational levels of C_3 are consistent with\nan excitation temperature of about 34 K." }, { "anchor": "This is not the feedback you have been looking for: nearby optical AGN\n rarely drive kpc-scale cold-gas outflows: We study the interstellar Na I $\\lambda \\lambda 5890, 5895$ (Na D)\nabsorption-line doublet in a nearly-complete sample of $\\sim$9900 nearby\nSeyfert 2 galaxies, in order to quantify the significance of optical AGN\nactivity in driving kpc-scale outflows that can quench star formation.\nComparison to a carefully matched sample of $\\sim$44,000 control objects\nindicates that the Seyfert and control population have similar Na D detection\nrates ($\\sim 5-6%$). Only 53 Seyferts (or 0.5% of the population) are found to\npotentially display galactic-scale winds, compared to 0.8% of the control\ngalaxies. While nearly a third of the Na D outflows observed in our Seyfert 2\ngalaxies occur around the brightest AGN, both radio and infrared data indicate\nthat star formation could play the dominant role in driving cold-gas outflows\nin an even higher fraction of the Na D-outflowing Seyfert 2s. Our results\nindicate that galactic-scale outflows at low redshift are no more frequent in\nSeyferts than they are in their non-active counterparts, that optical AGN are\nnot significant contributors to the quenching of star formation in the nearby\nUniverse, and that star-formation may actually be the principal driver of\noutflows even in systems that do host an AGN.", "positive": "Exploring the chemistry induced by energetic processing of the\n H2-bearing, CO-rich apolar ice layer: Interstellar ice mantles on the surfaces of dust grains are thought to have a\nbi-layered structure, with a H2O-rich polar layer, covered by a CO-rich apolar\nlayer that probably harbors H2 and other volatiles such as N2. In this work, we\nexplore the chemistry induced by 2 keV electrons and Ly-alpha photons in\nH2:CO:15N2 ice analogs of the CO-rich layer when exposed to similar fluences to\nthose expected from the cosmic-ray-induced secondary electrons and UV photons\nduring the typical lifetime of dense clouds. Six products were identified upon\n2 keV electron irradiation: CO2, C2O (and other carbon chainoxides), CH4, H2CO,\nH2C2O, and H15NCO. The total product abundances corresponded to 5-10% of the\ninitial CO molecules exposed to the electron irradiation. Ly-alpha photon\nirradiation delivered 1-2 orders of magnitude lower yields with a similar\nproduct branching ratio, which may be due to the low UV-photon absorption\ncross-section of the ice sample at this wavelength. Formation of additional\nN-bearing species, namely C215N2 and 15NH3, was only observed in the absence of\nH2 and CO molecules, respectively, suggesting that reactants derived from H2\nand CO molecules preferentially react with each other instead of with 15N2 and\nits dissociation products. In summary, ice chemistry induced by energetic\nprocessing of the CO-rich apolar ice layer provides alternative formation\npathways for several species detected in the interstellar medium, including\nsome related to the complex organic molecule chemistry. Further quantification\nof these pathways will help astrochemical models to constrain their relative\ncontribution to the interstellar budget of, especially, the organic species\nH2CO and HNCO." }, { "anchor": "Spectroscopy of Luminous Compact Blue Galaxies in Distant Clusters II.\n Physical Properties of dE Progenitor Candidates: Luminous Compact Blue Galaxies (LCBGs) are an extreme star-bursting\npopulation of galaxies that were far more common at earlier epochs than today.\nBased on spectroscopic and photometric measurements of LCBGs in massive (M\n>10^15 M_sun), intermediate redshift (0.5 < z < 0.9) galaxy clusters, we\npresent their rest-frame properties including star-formation rate, dynamical\nmass, size, luminosity, and metallicity. The appearance of these small, compact\ngalaxies in clusters at intermediate redshift helps explain the observed\nredshift evolution in the size-luminosity relationship among cluster galaxies.\nIn addition, we find the rest-frame properties of LCBGs appearing in galaxy\nclusters are indistinguishable from field LCBGs at the same redshift. Up to 35%\nof the LCBGs show significant discrepancies between optical and infrared\nindicators of star formation, suggesting that star formation occurs in obscured\nregions. Nonetheless, the star formation for LCBGs shows a decrease toward the\ncenter of the galaxy clusters. Based on their position and velocity, we\nestimate that up to 10% of cluster LCBGs are likely to merge with another\ncluster galaxy. Finally, the observed properties and distributions of the LCBGs\nin these clusters lead us to conclude that we are witnessing the quenching of\nthe progenitors of dwarf elliptical galaxies that dominate the number density\nof present-epoch galaxy clusters.", "positive": "The molecular gas kinematics in the host galaxy of non-repeating FRB\n 180924B: Fast radio bursts (FRBs) are millisecond-duration transients with large\ndispersion measures. The origin of FRBs is still mysterious. One of the methods\nto comprehend FRB origin is to probe the physical environments of FRB host\ngalaxies. Mapping molecular-gas kinematics in FRB host galaxies is critical\nbecause it results in star formation that is likely connected to the birth of\nFRB progenitors. However, most previous works of FRB host galaxies have focused\non its stellar component. Therefore, we, for the first time, report the\nmolecular gas kinematics in the host galaxy of the non-repeating FRB 180924B at\n$z= 0.3216$. Two velocity components of the CO (3-2) emission line are detected\nin its host galaxy with the Atacama Large Millimeter/submillimeter Array\n(ALMA): the peak of one component ($-155.40$ km s$^{-1}$) is near the centre of\nthe host galaxy, and another ($-7.76$ km s$^{-1}$) is near the FRB position.\nThe CO (3-2) spectrum shows asymmetric profiles with A$_{\\rm peak}$ $=2.03\\pm\n0.39$, where A$_{\\rm peak}$ is the peak flux density ratio between the two\nvelocity components. The CO (3-2) velocity map also indicates an asymmetric\nvelocity gradient from $-180$ km s$^{-1}$ to 8 km s$^{-1}$. These results\nindicate a disturbed kinetic structure of molecular gas in the host galaxy.\nSuch disturbed kinetic structures are reported for repeating FRB host galaxies\nusing HI emission lines in previous works. Our finding indicates that\nnon-repeating and repeating FRBs could commonly appear in disturbed kinetic\nenvironments, suggesting a possible link between the gas kinematics and FRB\nprogenitors." }, { "anchor": "Revealing the Dark Threads of the Cosmic Web: Modern cosmology predicts that matter in our Universe has assembled today\ninto a vast network of filamentary structures colloquially termed the Cosmic\nWeb. Because this matter is either electromagnetically invisible (i.e., dark)\nor too diffuse to image in emission, tests of this cosmic web paradigm are\nlimited. Wide-field surveys do reveal web-like structures in the galaxy\ndistribution, but these luminous galaxies represent less than 10% of baryonic\nmatter. Statistics of absorption by the intergalactic medium (IGM) via\nspectroscopy of distant quasars support the model yet have not conclusively\ntied the diffuse IGM to the web. Here, we report on a new method inspired by\nthe Physarum polycephalum slime mold that is able to infer the density field of\nthe Cosmic Web from galaxy surveys. Applying our technique to galaxy and\nabsorption-line surveys of the local Universe, we demonstrate that the bulk of\nthe IGM indeed resides in the Cosmic Web. From the outskirts of Cosmic Web\nfilaments, at approximately the cosmic mean matter density (rho_m) and approx.\n5 virial radii from nearby galaxies, we detect an increasing H I absorption\nsignature towards higher densities and the circumgalactic medium, to approx.\n200 rho_m. However, the absorption is suppressed within the densest\nenvironments, suggesting shock-heating and ionization deep within filaments\nand/or feedback processes within galaxies.", "positive": "The imprint of cosmic ray driven outflow on Lyman-alpha spectra: Recent magneto-hydrodynamic simulations of the star-forming interstellar\nmedium (ISM) with parsec scale resolution indicate that relativistic cosmic\nrays support the launching of galactic outflows on scales of a few kpc. If\nthese fundamental constituents of the ISM are injected at the sites of\nsupernova (SN) explosions, the outflows are smoother, colder, and denser than\nthe highly structured, hot-phase driven outflows forming, e.g., by thermal SN\nenergy injection alone. In this Letter we present computations of resonant\nLyman-$\\alpha$ (Ly$\\alpha$) radiation transfer through snapshots of a suite of\nstratified disk simulations from the SILCC project. For a range of thermal,\nradiative, and kinetic feedback models only simulations including non-thermal\ncosmic rays produce Ly$\\alpha$ spectra with enhanced red peaks and strong\nabsorption at line center -- similar to observed systems. The absence of cosmic\nray feedback leads to spectra incompatible with observations. We attribute this\nto the smoother neutral gas distribution of cosmic ray supported outflows\nwithin a few kpc from the disk midplane." }, { "anchor": "Star formation in dense clusters: A model of core-clump accretion with equally likely stopping describes star\nformation in the dense parts of clusters, where models of isolated collapsing\ncores may not apply. Each core accretes at a constant rate onto its protostar,\nwhile the surrounding clump gas accretes as a power of protostar mass. Short\naccretion flows resemble Shu accretion, and make low-mass stars. Long flows\nresemble reduced Bondi accretion and make massive stars. Accretion stops due to\nenvironmental processes of dynamical ejection, gravitational competition, and\ngas dispersal by stellar feedback, independent of initial core structure. The\nmodel matches the field star IMF from 0.01 to more than 10 solar masses. The\ncore accretion rate and the mean accretion duration set the peak of the IMF,\nindependent of the local Jeans mass. Massive protostars require the longest\naccretion durations, up to 0.5 Myr. The maximum protostar luminosity in a\ncluster indicates the mass and age of its oldest protostar. The distribution of\nprotostar luminosities matches those in active star-forming regions if\nprotostars have a constant birthrate but not if their births are coeval. For\nconstant birthrate, the ratio of YSOs to protostars indicates the star-forming\nage of a cluster, typically ~1 Myr. The protostar accretion luminosity is\ntypically less than its steady spherical value by a factor of ~2, consistent\nwith models of episodic disk accretion.", "positive": "Seen and unseen: bursty star formation and its implications for\n observations of high-redshift galaxies with JWST: Both observations and simulations have shown strong evidence for highly\ntime-variable star formation in low-mass and/or high-redshift galaxies, which\nhas important observational implications because high-redshift galaxy samples\nare rest-UV selected and therefore particularly sensitive to the recent star\nformation. Using a suite of cosmological \"zoom-in\" simulations at $z>5$ from\nthe Feedback in Realistic Environments (FIRE) project, we examine the\nimplications of bursty star formation histories for observations of\nhigh-redshift galaxies with JWST. We characterize how the galaxy observability\ndepends on the star formation history. We also investigate selection effects\ndue to bursty star formation on the physical properties measured, such as the\ngas fraction, specific star formation rate, and metallicity. We find the\nobservability to be highly time-dependent for galaxies near the survey's\nlimiting flux due to the SFR variability: as the star formation rate\nfluctuates, the same galaxy oscillates in and out of the observable sample. The\nobservable fraction $f_\\mathrm{obs} = 50\\%$ at $z \\sim 7$ and $M_{\\star} \\sim\n10^{8.5}$ to $10^{9}\\,M_{\\odot}$ for a JWST/NIRCam survey reaching a limiting\nmagnitude of $m^\\mathrm{lim}_\\mathrm{AB} \\sim 29$-$30$, representative of\nsurveys such as JADES and CEERS. JWST-detectable galaxies near the survey limit\ntend to have properties characteristic of galaxies in the bursty phase: on\naverage, they show approximately 2.5 times higher cold, dense gas fractions and\n20 times higher specific star formation rates at a given stellar mass than\ngalaxies below the rest-UV detection threshold. Our study represents a first\nstep in quantifying selection effects and the associated biases due to bursty\nstar formation in studying high-redshift galaxy properties." }, { "anchor": "RUBIES: JWST/NIRSpec Confirmation of an Infrared-luminous, Broad-line\n Little Red Dot with an Ionized Outflow: The JWST discovery of ``little red dots'' (LRDs) is reshaping our picture of\nthe early Universe, yet the physical mechanisms driving their compact size and\nUV-optical colors remain elusive. Here we report an unusually bright LRD\n($z=3.1$) observed as part of the RUBIES program. This LRD exhibits broad\nemission lines (FWHM $\\sim4000$km/s), a blue UV continuum, a clear Balmer break\nand a red continuum sampled out to rest 4 $\\mu$m with MIRI. We develop a new\njoint galaxy and AGN model within the Prospector Bayesian inference framework\nand perform spectrophotometric modeling using NIRCam, MIRI, and NIRSpec/Prism\nobservations. Our fiducial model reveals a $M_*\\sim 10^9M_\\odot$ galaxy\nalongside a dust-reddened AGN driving the optical emission. Explaining the\nrest-frame optical color as a reddened AGN requires $A_{\\rm v}\\gtrsim4$,\nsuggesting that a great majority of the accretion disk energy is re-radiated as\ndust emission. Yet despite clear AGN signatures, we find a surprising lack of\nhot torus emission, which implies that either the dust emission in this object\nmust be cold, or the red continuum must instead be driven by a massive, evolved\nstellar population of the host galaxy -- seemingly inconsistent with the high\nEW broad lines (H$\\alpha$ EW $\\sim800$\\AA). The widths and luminosities of\nPa$\\beta$, Pa$\\delta$, Pa$\\gamma$, and H$\\alpha$ imply a modest black hole mass\nof $M_{\\rm BH}\\sim10^8M_\\odot$. Additionally, we identify a narrow blue-shifted\nHeI absorption in G395M spectra, signaling an ionized outflow with kinetic\nenergy up to $\\sim1$\\% the luminosity of the AGN. The low redshift of\nRUBIES-BLAGN-1 combined with the depth and richness of the JWST imaging and\nspectroscopic observations provide a unique opportunity to build a physical\nmodel for these so-far mysterious LRDs, which may prove to be a crucial phase\nin the early formation of massive galaxies and their supermassive black holes.", "positive": "Optical Properties of C$-$rich ($^{12}$C, SiC and FeC) Dust Layered\n Structure of Massive Stars: The composition and structure of interstellar dust are important and complex\nfor the study of the evolution of stars and the \\textbf{interstellar medium}\n(ISM). However, there is a lack of corresponding experimental data and model\ntheories. By theoretical calculations based on ab-initio method, we have\npredicted and geometry optimized the structures of Carbon-rich (C-rich) dusts,\ncarbon ($^{12}$C), iron carbide (FeC), silicon carbide (SiC), even silicon\n($^{28}$Si), iron ($^{56}$Fe), and investigated the optical absorption\ncoefficients and emission coefficients of these materials in 0D\n(zero$-$dimensional), 1D, and 2D nanostructures. Comparing the \\textbf{nebular\nspectra} of the supernovae (SN) with the coefficient of dust, we find that the\noptical absorption coefficient of the 2D $^{12}$C, $^{28}$Si, $^{56}$Fe, SiC\nand FeC structure corresponds to the absorption peak displayed in the infrared\nband (5$-$8) $\\mu$$m$ of the spectrum at 7554 days after the SN1987A explosion.\nAnd it also corresponds to the spectrum of 535 days after the explosion of\nSN2018bsz, when the wavelength in the range of (0.2$-$0.8) and (3$-$10)\n$\\mu$$m$. Nevertheless, 2D SiC and FeC corresponds to the spectrum of 844 days\nafter the explosion of SN2010jl, when the wavelength is within (0.08$-$10)\n$\\mu$$m$. Therefore, FeC and SiC may be the second type of dust in SN1987A\ncorresponding to infrared band (5$-$8) $\\mu$$m$ of dust and may be in the\nejecta of SN2010jl and SN2018bsz." }, { "anchor": "Contamination of stellar-kinematic samples and uncertainty about dark\n matter annihilation profiles in ultrafaint dwarf galaxies: the example of\n Segue I: The expected gamma-ray flux coming from dark matter annihilation in dwarf\nspheroidal (dSph) galaxies depends on the so-called `J-factor', the integral of\nthe squared dark matter density along the line-of-sight. We examine the degree\nto which estimates of J are sensitive to contamination (by foreground Milky Way\nstars and stellar streams) of the stellar-kinematic samples that are used to\ninfer dark matter densities in `ultrafaint' dSphs. Applying standard kinematic\nanalyses to hundreds of mock data sets that include varying levels of\ncontamination, we find that mis-classified contaminants can cause J-factors to\nbe overestimated by orders of magnitude. Stellar-kinematic data sets for which\nwe obtain such biased estimates tend 1) to include relatively large fractions\nof stars with ambiguous membership status, and 2) to give estimates for J that\nare sensitive to specific choices about how to weight and/or to exclude stars\nwith ambiguous status. Comparing publicly-available stellar-kinematic samples\nfor the nearby dSphs Reticulum~II and Segue~I, we find that only the latter\ndisplays both of these characteristics. Estimates of Segue~I's J-factor should\ntherefore be regarded with a larger degree of caution when planning and\ninterpreting gamma-ray observations. Moreover, robust interpretations regarding\ndark matter annihilation in dSph galaxies in general will require explicit\nexamination of how interlopers might affect the inferred dark matter density\nprofile.", "positive": "Kepler observations of the eclipsing cataclysmic variable KIS\n J192748.53+444724.5: We present results from long cadence Kepler observations covering 97.6 days\nof the newly discovered eclipsing cataclysmic variable KIS\nJ192748.53+444724.5/KIC 8625249. We detect deep eclipses of the accretion disk\nby the donor star every 3.97 hours. Additionally, the Kepler observations also\ncover a full outburst for this cataclysmic variable, making KIS\nJ192748.53+444724.5 the second known eclipsing cataclysmic variable system in\nthe Kepler field of view. We show how in quiescence a significant component\nassociated to the hot-spot is visible preceding the eclipse, and that this\ncomponent is swamped by the brightness increase during the outburst,\npotentially associated with the accretion disk. Furthermore we present evidence\nfor accretion disk radius changes during the outburst by analysing the\nout-of-eclipse light levels and eclipse depth through each orbital cycle. We\nshow how these parameters are linearly correlated in quiescence, and discuss\nhow their evolution during the outburst is suggesting disk radius changes\nand/or radial temperature gradient variations in the disk." }, { "anchor": "Diagnosing the interstellar medium of galaxies with far-infrared\n emission lines I. The [C II] 158 microns line at z~0: Atomic fine structure lines have been detected in the local Universe and at\nhigh redshifts over the past decades. The [C II] emission line at 158 $\\mu$m is\nan important observable as it provides constraints on the interstellar medium\n(ISM) cooling processes. We develop a physically motivated framework to\nsimulate the production of far-infrared line emission from galaxies in a\ncosmological context. This first paper sets out our methodology and describes\nits first application, simulating the [C II] 158 $\\mu$m line emission in the\nlocal Universe. We combine the output from EAGLE cosmological hydrodynamical\nsimulations with a multi-phase model of the ISM. Gas particles are divided into\nthree phases: dense molecular gas, neutral atomic gas and diffuse ionised gas\n(DIG). We estimate the [C II] line emission from the three phases using a set\nof Cloudy cooling tables. Our results agree with previous findings regarding\nthe contribution of these three ISM phases to the [C II] emission. Our model\nshows good agreement with the observed ${\\rm L_{[C II]}}$-star formation rate\n(SFR) relation in the local Universe within 0.4 dex scatter. The fractional\ncontribution to the [C II] line from different ISM phases depends on the total\nSFR and metallicity. The neutral gas phase dominates the [C II] emission in\ngalaxies with $\\rm{SFR}\\sim0.01$-$1\\,\\rm{M_{\\odot}}\\,\\rm{yr^{-1}}$, but the\nionised phase dominates at lower SFRs. Galaxies above solar metallicity exhibit\nlower ${\\rm L_{[C II]}}$/SFR ratios for the neutral phase. In comparison, the\n${\\rm L_{[C II]}}$/SFR ratio in the DIG is stable when metallicity varies. We\nsuggest that the reduced size of the neutral clouds, caused by increased SFRs,\nis the likely cause for the ${\\rm L_{[C II]}}$ deficit at high infrared\nluminosities, although EAGLE simulations do not reach these luminosities at\n$z=0$.", "positive": "The role of neutral hydrogen in setting the abundances of molecular\n species in the Milky Way's diffuse interstellar medium. I. Observational\n constraints from ALMA and NOEMA: We have complemented existing observations of HI absorption with new\nobservations of HCO$^+$, C$_2$H, HCN, and HNC absorption from the Atacama Large\nMillimeter/submillimeter Array (ALMA) and the Northern Extended Millimeter\nArray (NOEMA) in the direction of 20 background radio continuum sources with\n$4^\\circ \\leq |b| \\leq 81^\\circ$ to constrain the atomic gas conditions that\nare suitable for the formation of diffuse molecular gas. We find that these\nmolecular species form along sightlines where $A_V \\gtrsim 0.25$, consistent\nwith the threshold for the HI-to-H$_2$ transition at solar metallicity.\nMoreover, we find that molecular gas is associated only with structures that\nhave an HI optical depth $> 0.1$, a spin temperature $< 80$ K, and a turbulent\nMach number $\\gtrsim 2$. We also identify a broad, faint component to the\nHCO$^+$ absorption in a majority of sightlines. Compared to the velocities\nwhere strong, narrow HCO$^+$ absorption is observed, the HI at these velocities\nhas a lower cold neutral medium (CNM) fraction and negligible CO emission. The\nrelative column densities and linewidths of the different molecular species\nobserved here are similar to those observed in previous experiments over a\nrange of Galactic latitudes, suggesting that gas in the solar neighborhood and\ngas in the Galactic plane are chemically similar. For a select sample of\npreviously-observed sightlines, we show that the absorption line profiles of\nHCO$^+$, HCN, HNC, and C$_2$H are stable over periods of $\\sim 3$ years and\n$\\sim 25$ years, likely indicating that molecular gas structures in these\ndirections are at least $\\gtrsim 100$ AU in size" }, { "anchor": "The VANDELS ESO public spectroscopic survey: observations and first data\n release: This paper describes the observations and the first data release (DR1) of the\nESO public spectroscopic survey \"VANDELS, a deep VIMOS survey of the CANDELS\nCDFS and UDS fields\". VANDELS' main targets are star-forming galaxies at\n2.4 5.6: We present the low-frequency radio spectra of 9 high-redshift quasars at $5.6\n\\leq z \\leq 6.6$ using the Giant Metre Radio Telescope band-3, -4, and -5\nobservations ($\\sim$300-1200 MHz), archival Low Frequency Array (LOFAR; 144\nMHz), and Very Large Array (VLA; 1.4 and 3 GHz) data. Five of the quasars in\nour sample have been discovered recently, representing some of the highest\nredshift radio bright quasars known at low-frequencies. We model their radio\nspectra to study their radio emission mechanism and age of the radio jets by\nconstraining the spectral turnover caused by synchrotron self-absorption (SSA)\nor free-free absorption (FFA). Besides J0309+2717, a blazar at $z=6.1$, our\nquasars show no sign of a spectral flattening between 144 MHz and a few GHz,\nindicating there is no strong SSA or FFA absorption in the observed frequency\nrange. However, we find a wide range of spectral indices between $-1.6$ and\n$0.05$, including the discovery of 3 potential ultra-steep spectrum quasars.\nUsing further archival VLBA data, we confirm that the radio SED of the blazar\nJ0309+2717 likely turns over at a rest-frame frequency of 0.6-2.3 GHz (90-330\nMHz observed frame), with a high-frequency break indicative of radiative ageing\nof the electron population in the radio lobes. Ultra-low frequency data below\n50 MHz are necessary to constrain the absorption mechanism for J0309+2717 and\nthe turnover frequencies for the other high-$z$ quasars in our sample. A\nrelation between linear radio jet size and turnover frequency has been\nestablished at low redshifts. If this relation were to hold at high redshifts,\nthe limits on the turnover frequency of our sample suggest the radio jet sizes\nmust be more extended than the typical sizes observed in other radio-bright\nquasars at similar redshift. To confirm this deep radio follow-up observations\nwith high spatial resolution are required." }, { "anchor": "A new distant Milky Way globular cluster in the Pan-STARRS1 3\u03c0\n survey: We present a new satellite in the outer halo of the Galaxy, the first Milky\nWay satellite found in the stacked photometric catalog of the Panoramic Survey\nTelescope and Rapid Response System 1 (Pan-STARRS1) Survey. From follow-up\nphotometry obtained with WFI on the MPG/ESO 2.2m telescope, we argue that the\nobject, located at a heliocentric distance of 145+/-17 kpc, is the most distant\nMilky Way globular cluster yet known. With a total magnitude of M_V=-4.3+/-0.2\nand a half-light radius of 20+/-2 pc, it shares the properties of extended\nglobular clusters found in the outer halo of our Galaxy and the Andromeda\ngalaxy. The discovery of this distant cluster shows that the full spatial\nextent of the Milky Way globular cluster system has not yet been fully\nexplored.", "positive": "Dark Matter Strikes Back: Mc Gaugh et al. (2016) have found, by investigating a large sample of\nSpirals, a tight non linear relationship between the total radial acceleration,\nconnected with the Dark Matter phenomenon, and its component which comes from\nthe distribution of baryonic matter, as the stellar and HI disks. The strong\nlink between these two quantities is considered by them and by other\nresearchers, as challenging the scenario featuring the presence of DM halos in\ngalaxies. Or, at least, to indicate the peculiar nature of the underlying dark\nmatter particles. We have explored this issue by investigating a larger number\nof galaxies by means of several techniques of analysis. Our results support and\neven increase, both qualitatively and quantitatively, the validity of McGaugh\net al. (2016) 's relationship. However, we prove that such relationship exists\nalso in the scenario featuring dark matter halos + ordinary baryonic matter and\nthat it arises by the fact the DM is less concentrated than the luminous matter\nand it is progressively more abundant in lower luminosity objects. These\nproperties are due to well known astrophysical effects: the implications of\nthis relationship for the properties of dark matter halos are nothing of new or\nof unexpected. The relationship, definitively, is not a portal to go beyond the\nstandard picture of $\\Lambda$CDM galaxy formation." }, { "anchor": "Are Type Ia Supernovae in Restframe $H$ Brighter in More Massive\n Galaxies?: We analyze 143 Type Ia supernovae (SNeIa) observed in $H$ band (1.6-1.8\n$\\mu$m) and find SNeIa are intrinsically brighter in $H$-band with increasing\nhost galaxy stellar mass. We find SNeIa in galaxies more massive than\n$10^{10.43} M_{\\odot}$ are $0.13 \\pm 0.04$ mag brighter in $H$ than SNeIa in\nless massive galaxies. The same set of SNeIa observed at optical wavelengths,\nafter width-color-luminosity corrections, exhibit a $0.10 \\pm 0.03$ mag offset\nin the Hubble residuals. We observe an outlier population ($|\\Delta H_{\\rm\nmax}| > 0.5$ mag) in the $H$ band and show that removing the outlier population\nmoves the mass threshold to $10^{10.65} M_{\\odot}$ and reduces the step in $H$\nband to $0.08 \\pm 0.04$ mag, but the equivalent optical mass step is increased\nto $0.13 \\pm 0.04$ mag. We conclude the outliers do not drive the\nbrightness--host-mass correlation. Less massive galaxies preferentially host\nmore higher-stretch SNeIa, which are intrinsically brighter and bluer. It is\nonly after correction for width-luminosity and color-luminosity relationships\nthat SNeIa have brighter optical Hubble residuals in more massive galaxies.\nThus finding SNeIa are intrinsically brighter in $H$ in more massive galaxies\nis an opposite correlation to the intrinsic (pre-width-luminosity correction)\noptical brightness. If dust and the treatment of intrinsic color variation were\nthe main driver of the host galaxy mass correlation, we would not expect a\ncorrelation of brighter $H$-band SNeIa in more massive galaxies.", "positive": "The Galactic Faraday rotation sky 2020: This work gives an update to existing reconstructions of the Galactic Faraday\nrotation sky by processing almost all Faraday rotation data sets available at\nthe end of the year 2020. Observations of extra-Galactic sources in recent\nyears have, among other regions, further illuminated the previously\nunder-constrained southern celestial sky, as well as parts of the inner disc of\nthe Milky Way. This has culminated in an all-sky data set of 55,190 data\npoints, which is a significant expansion on the 41,330 used in previous works,\nhence making an updated separation of the Galactic component a promising\nventure. The increased source density allows us to present our results in a\nresolution of about $1.3\\cdot 10^{-2}\\, \\mathrm{deg}^2$\n($46.8\\,\\mathrm{arcmin}^2$), which is a twofold increase compared to previous\nworks. As for previous Faraday rotation sky reconstructions, this work is based\non information field theory, a Bayesian inference scheme for field-like\nquantities which handles noisy and incomplete data. In contrast to previous\nreconstructions, we find a significantly thinner and pronounced Galactic disc\nwith small-scale structures exceeding values of several thousand\n$\\mathrm{rad}\\,\\mathrm{m}^{-2}$. The improvements can mainly be attributed to\nthe new catalog of Faraday data, but are also supported by advances in\ncorrelation structure modeling within numerical information field theory. We\nfurthermore give a detailed discussion on statistical properties of the Faraday\nrotation sky and investigate correlations to other data sets." }, { "anchor": "The role of HI in regulating size growth of local galaxies: We study the role of atomic hydrogen (HI) in regulating size growth of local\ngalaxies. The size of a galaxy, $D_{\\rm r,~25}$, is characterized by the\ndiameter at which the $r-$band surface brightness reaches $\\mu_{\\rm r}=25.0~\\rm\nmag~arcsec^{-2}$. We find that the positions of galaxies in the size ($D_{\\rm\nr,~25}$)$-$stellar mass ($M_{\\ast}$) plane strongly depend on their\nHI-to-stellar mass ratio ($M_{\\rm HI}/M_{\\ast}$). In the HI-rich regime,\ngalaxies that are more rich in HI tend to have larger sizes. Such a trend is\nnot seen in the HI-poor regime, suggesting that size growth is barely affected\nby the HI content when it has declined to a sufficiently low level. An\ninvestigation of the relations between size, $M_{\\rm HI}/M_{\\ast}$ and star\nformation rate (SFR) suggests that size is more intrinsically linked with\n$M_{\\rm HI}/M_{\\ast}$, rather than SFR. We further examine the HI-to-stellar\ndisk size ratio ($D_{\\rm HI}/D_{\\rm r,~25}$) of galaxies and find that at\nlog($M_{\\rm HI}/M_{\\ast})>-0.7$, $D_{\\rm HI}/D_{\\rm r,~25}$ is weakly\ncorrelated with $M_{\\ast}$. These findings support a picture in which the\nHI-rich galaxies live in an inside-out disk growing phase regulated by gas\naccretion and star formation. The angular momentum of the accreted materials is\nprobably the key parameter in shaping the size of an HI-rich galaxy.", "positive": "3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since\n $z=3$: Spectroscopic + photometric redshifts, stellar mass estimates, and rest-frame\ncolors from the 3D-HST survey are combined with structural parameter\nmeasurements from CANDELS imaging to determine the galaxy size-mass\ndistribution over the redshift range 03x10^9 M_sol, and steep, R_eff M_star^0.75, for\nearly-type galaxies with stellar mass >2x10^10 M_sol. The intrinsic scatter is\n<~0.2 dex for all galaxy types and redshifts. For late-type galaxies, the\nlogarithmic size distribution is not symmetric, but skewed toward small sizes:\nat all redshifts and masses a tail of small late-type galaxies exists that\noverlaps in size with the early-type galaxy population. The number density of\nmassive (~10^11 M_sol), compact (R_eff < 2 kpc) early-type galaxies increases\nfrom z=3 to z=1.5-2 and then strongly decreases at later cosmic times." }, { "anchor": "MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. II - Star\n Formation Histories and Galaxy Quenching: We investigate the stellar populations for a sample of 24 quiescent galaxies\nat 1.5 < z < 2.5 using deep rest-frame optical spectra obtained with Keck\nMOSFIRE. By fitting templates simultaneously to the spectroscopic and\nphotometric data, and exploring a variety of star formation histories, we\nobtain robust measurements of median stellar ages and residual levels of star\nformation. After subtracting the stellar templates, the stacked spectrum\nreveals the Halpha and [NII] emission lines, providing an upper limit on the\nongoing star formation rate of 0.9 +/- 0.1 Msun/yr. By combining the MOSFIRE\ndata to our sample of Keck LRIS spectra at lower redshift, we analyze in a\nconsistent manner the quiescent population at 1 < z < 2.5. We find a tight\nrelation (with a scatter of 0.13 dex) between the stellar age and the\nrest-frame U-V and V-J colors, which can be used to estimate the age of\nquiescent galaxies given their colors. Applying this age--color relation to\nlarge, photometric samples, we are able to model the number density evolution\nfor quiescent galaxies of various ages. We find evidence for two distinct\nquenching paths: a fast quenching that produces compact post-starburst systems,\nand a slow quenching of larger galaxies. Fast quenching accounts for about a\nfifth of the growth of the red sequence at z~1.4, and half at z~2.2. We\nconclude that fast quenching is triggered by dramatic events such as gas-rich\nmergers, while slow quenching is likely caused by a different physical\nmechanism.", "positive": "Towards ultra metal-poor DLAs: linking the chemistry of the most\n metal-poor DLA to the first stars: We present new Keck/HIRES data of the most metal-poor damped Lyman-alpha\n(DLA) system currently known. By targeting the strongest accessible Fe II\nfeatures, we have improved the upper limit of the [Fe/H] abundance\ndetermination by ~1 dex, finding [Fe/H]<-3.66 (2 sigma). We also provide the\nfirst upper limit on the relative abundance of an odd-atomic number element for\nthis system [Al/H]<-3.82 (2 sigma). Our analysis thus confirms that this\nz_abs=3.07 DLA is not only the most metal-poor DLA but also the most iron-poor\nDLA currently known. We use the chemistry of this DLA, combined with a\nstochastic chemical enrichment model, to probe its enrichment history. We find\nthat this DLA is best modelled by the yields of an individual Population III\nprogenitor rather than multiple Population III stars. We then draw comparisons\nwith other relic environments and, particularly, the stars within nearby\nultra-faint dwarf galaxies. We identify a star within Bootes I, with a similar\nchemistry to that of the DLA presented here, suggesting that it may have been\nborn in a gas cloud that had similar properties. The extremely metal-poor DLA\nat redshift z_abs=3.07 (i.e. ~2 Gyrs after the Big Bang) may reside in one of\nthe least polluted environments in the early Universe." }, { "anchor": "Dynamical effects of the scale invariance of the empty space: The fall\n of dark matter ?: The hypothesis of the scale invariance of the macroscopic empty space, which\nintervenes through the cosmological constant, has led to new cosmological\nmodels. They show an accelerated cosmic expansion and satisfy several major\ncosmological tests. No unknown particles are needed. Developing the weak field\napproximation, we find that the here derived equation of motion corresponding\nto Newton's equation also contains a small outwards acceleration term. The new\nterm is particularly significant for very low density systems.\n A modified virial theorem is derived and applied to clusters of galaxies. For\nthe Coma and Abell 2029 clusters, the dynamical masses are about a factor of 5\nto 10 smaller than in the standard case. This tends to let no room for dark\nmatter in these clusters. Then, the two-body problem is studied and an equation\ncorresponding to the Binet equation is obtained. The results are applied to the\nrotation curve of the outer layers of the Milky Way. Starting backwards from\nthe present rotation curve, we calculate the past evolution of the galactic\nrotation and find that, in the early stages, it was steep and Keplerian. Thus,\nthe flat rotation curves of galaxies appears as an age effect, a result\nconsistent with recent observations of distant galaxies by Genzel et al. (2017)\nand Lang et al. (2017). Finally, in an Appendix we also study the long-standing\nproblem of the increase with age of the vertical velocity dispersion in the\nGalaxy. The observed increase appears to result from the new small acceleration\nterm in the equation of the harmonic oscillator describing stellar motions\naround the galactic plane. Thus, we tend to conclude that neither the dark\nenergy, nor the dark matter seem to be needed in the proposed theoretical\ncontext.", "positive": "The influence of globular cluster evolution on the specific frequency in\n dwarf galaxies: Dwarf galaxies are known to exhibit an unusual richness in numbers of\nglobular clusters (GCs), property quantified by the specific frequency ($S_N$),\nwhich is high for dwarf and giant elliptical galaxies, but with a minimum for\nintermediate-mass galaxies. In this work we study the role that GC evolution\nhas in setting this trend, for which we use ${\\it N}$-body simulations to\nevolve GCs in dwarf galaxies and quantify their disruption efficiency. We\nselected five individual dwarf galaxies from a high-resolution cosmological\nsimulation, which includes GC formation and follow-up of their paths inside the\nhost galaxy. Then, the tidal history of each GC is coupled to NBODY6++GPU to\nproduce ${\\it N}$-body models that account for both, the interaction of GCs\nwith their galactic environment and their internal dynamics. This results in a\nGC mass loss parameterization to estimate dissolution times and mass loss rates\nafter a Hubble time. GC evolution is sensitive to the particular orbital\nhistories within each galaxy, but the overall result is that the amount of mass\nthat GC systems lose scales with the mass (and density) of the host galaxy,\ni.e., the GC mass loss efficiency is lowest in low-mass dwarfs. After a 12 Gyr\nevolution all simulated GC systems retain an important fraction of their\ninitial mass (up to 25%), in agreement with the high GC to field star ratios\nobserved in some dwarfs, and supports the scenario in which GC disruption\nmechanisms play an important role in shaping the GC specific frequency in dwarf\ngalaxies." }, { "anchor": "Towards a census of high-redshift dusty galaxies with\n $\\mathit{Herschel}$: A selection of \"500 $\u03bc$m-risers\": $\\mathit{Herschel}$ extragalactic surveys offer a unique opportunity to\nefficiently select a significant number of rare and massive dusty objects, and\nthus gain insight into the prodigious star-forming activity that takes place in\nthe very distant Universe. To search for $z\\geq4$ dusty star-forming galaxies,\nin this work we consider red SPIRE objects with fluxes rising from 250 $\\mu$m\nto $500\\:\\mu$m (so-called \"500 $\\mu$m-risers\"). We aim to implement a novel\nmethod to obtain a statistical sample of \"500 $\\mu$m-risers\" and fully evaluate\nour selection inspecting different models of galaxy evolution. We consider one\nof the largest and deepest ${\\it Herschel}$ surveys, the Herschel Virgo Cluster\nSurvey. We develop a novel selection algorithm which links the source\nextraction and spectral energy distribution fitting. We select 133 \"500\n$\\mu$m-risers\" over 55 deg$^{2}$, imposing the criteria:\n$S_{500}>S_{350}>S_{250}$, $S_{250}>13.2$ mJy and $S_{500}>$30 mJy.\nDifferential number counts are in a fairly good agreement with models,\ndisplaying better match than other existing samples. In order to interpret the\nstatistical properties of selected sources, which has been proven as a very\nchallenging task due the complexity of observed artefacts, we make end-to-end\nsimulations including physical clustering and lensing. The estimated fraction\nof strongly lensed sources is $24^{+6}_{-5}\\%$ based on models. We present the\nfaintest known statistical sample of \"500 $\\mu$m-risers\" and show that noise\nand strong lensing have crucial impact on measured counts and redshift\ndistribution of selected sources. We estimate the flux-corrected star formation\nrate density at $44$ sources.", "positive": "The driving of turbulence in simulations of molecular cloud formation\n and evolution: Molecular clouds are to a great extent influenced by turbulent motions in the\ngas. Numerical and observational studies indicate that the star formation rate\nand efficiency crucially depend on the mixture of solenoidal and compressive\nmodes in the turbulent acceleration field, which can be quantified by the\nturbulent driving parameter b. For purely solenoidal (divergence-free) driving\nprevious studies showed that b=1/3 and for entirely compressive (curl-free)\ndriving b=1. In this study, we determine the evolution of the turbulent driving\nparameter b in magnetohydrodynamical simulations of molecular cloud formation\nand evolution. The clouds form due to the convergence of two flows of warm\nneutral gas. We explore different scenarios by varying the magnitude of the\ninitial turbulent perturbations in the flows. We show that the driving mode of\nthe turbulence within the cloud strongly fluctuates with time and exhibits no\nclear correlation with typical cloud properties, such as the cloud mass and the\n(Alfven) Mach number. We specifically find that $b$ strongly varies from b=0.3\nto b=0.8 on timescales t<5 Myr, where the timescale and range of variation can\nchange from cloud to cloud. This rapid change of b from solenoidal to\ncompressive driving is primarily associated with global contraction of the\ncloud and subsequent onset of star formation. We conclude that the effective\nturbulence driving parameter should be treated as a free parameter that can\nvary from solenoidal to compressive in both time and space." }, { "anchor": "High angular resolution polarimetric imaging of the nucleus of NGC 1068:\n Disentangling the polarising mechanisms: Polarisation is a decisive method to study the inner region of active\ngalactic nuclei (AGNs) since it is not affected by contrast issues similarly to\nhow classical imaging is. When coupled to high angular resolution (HAR),\npolarisation can help to disentangle the location of the various polarising\nmechanisms and then give an insight on the physics taking place on the core of\nAGNs. We obtained a new data set of HAR polarimetric images of the archetypal\nSeyfert 2 nucleus of NGC 1068 observed with SPHERE/VLT and we aim in this paper\nat presenting the polarisation maps and at spatially separating the location of\nthe polarising mechanisms, thus deriving constraints on the organisation of the\ndust material in the inner region of this AGN. We then compared these\nmeasurements to radiative transfer simulations of scattering and dichroic\nabsorption processes, using the Monte-Carlo code MontAGN. We establish a\ndetailed table of the relative importance of the polarising mechanism as a\nfunction of the aperture and of the wavelength. We are able to separate the\ndominant polarising mechanisms in the three regions of the ionisation cone, the\nextended envelop of the torus and the very central bright source of the AGN.\nThus, we estimate the contribution of the different polarisation mechanisms to\nthe observed polarisation flux in these regions. Dichroic absorption is\nestimated to be responsible for about 99 % of the polarised flux coming from\nthe photo-centre. However, this contribution would be restricted to this\nlocation only, double scattering process being the most important contributor\nto polarisation in the equatorial plane of the AGN and single scattering being\ndominant in the polar outflow bi-cone.", "positive": "To test $R_{NLRs}~-~L_{O3}$ relation for narrow emission line regions of\n AGN through low redshift Type-2 AGN in SDSS: Sizes of narrow emission line regions (NLRs) of AGN could be estimated by\n[O~{\\sc iii}] line luminosity $L_{O3}$ through the known $R_{NLRs}-L_{O3}$\nempirical relations. Unfortunately, it is not convenient to test the\n$R_{NLRs}-L_{O3}$ empirical relations through structure properties of spatially\nresolved NLRs of large samples of AGN. In this manuscript, a method is proposed\nto test the $R_{NLRs}-L_{O3}^{\\sim0.25}$ empirical relations for AGN NLRs\nthrough SDSS Type-2 AGN having few orientation effects on NLRs sizes expected\nby AGN unified model, after considering sizes $R_{fib}$ of SDSS fiber covered\nregions. Comparing $R_{fib}$ and $R_{NLRs}$ estimated by $L_{O3}$, Type-2 AGN\nwith $R_{fib}>R_{NLRs}$ (Sample-II) and with $R_{fib}300K) and high gas densities (>10^4 cm^-3).\n\"The Eye\" is found at an interface between a large-scale minor axis inflow and\nthe Medusa central region. The extreme conditions inside \"the Eye\" may be the\nresult of the radiative and mechanical feedback from a deeply embedded, young,\nmassive super star cluster, formed due to the gas pile-up at the intersection.\nAlternatively, shocks from the inflowing gas may be strong enough to shock and\nfragment the gas. For both scenarios, however, it appears that the HCN and HCO+\ndense gas tracers are not probing star formation, but instead a post-starburst\nand/or shocked ISM that is too hot and fragmented to form new stars. Thus,\ncaution is advised in linking the detection of emission from dense gas tracers\nto evidence of ongoing or imminent star formation.", "positive": "Ice and Dust in the Quiescent Medium of Isolated Dense Cores: The relation between ices in the envelopes and disks surrounding YSOs and\nthose in the quiescent interstellar medium is investigated. For a sample of 31\nstars behind isolated dense cores, ground-based and Spitzer spectra and\nphotometry in the 1-25 um wavelength range are combined. The baseline for the\nbroad and overlapping ice features is modeled, using calculated spectra of\ngiants, H2O ice and silicates. The adopted extinction curve is derived\nempirically. Its high resolution allows for the separation of continuum and\nfeature extinction. The extinction between 13-25 um is ~50% relative to that at\n2.2 um. The strengths of the 6.0 and 6.85 um absorption bands are in line with\nthose of YSOs. Thus, their carriers, which, besides H2O and CH3OH, may include\nNH4+, HCOOH, H2CO and NH3, are readily formed in the dense core phase, before\nstars form. The 3.53 um C-H stretching mode of solid CH3OH was discovered. The\nCH3OH/H2O abundance ratios of 5-12% are larger than upper limits in the Taurus\nmolecular cloud. The initial ice composition, before star formation occurs,\ntherefore depends on the environment. Signs of thermal and energetic processing\nthat were found toward some YSOs are absent in the ices toward background\nstars. Finally, the peak optical depth of the 9.7 um band of silicates relative\nto the continuum extinction at 2.2 um is significantly shallower than in the\ndiffuse interstellar medium. This extends the results of Chiar et al. (2007) to\na larger sample and higher extinctions." }, { "anchor": "The HII region G35.673-00.847: another case of triggered star formation?: As part of a systematic study that we are performing with the aim to increase\nthe observational evidence of triggered star formation in the surroundings of\nHII regions, we analyze the ISM around the HII region G35.673-00.847, a poorly\nstudied source. Using data from large-scale surveys: Two Micron All Sky Survey,\nGalactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), MIPSGAL,\nGalactic Ring Survey (GRS), VLA Galactic Plane Survey (VGPS), and NRAO VLA Sky\nSurvey (NVSS) we performed a multiwavelength study of G35.673-00.847 and its\nsurroundings. The mid IR emission, shows that G35.673-00.847 has an almost\nsemi-ring like shape with a cut towards the galactic west. The radius of this\nsemi-ring is about 1.5' (~1.6 pc, at the distance of ~3.7 kpc). The distance\nwas estimated from an HI absorption study and from the analysis of the\nmolecular gas. Indeed, we find a molecular shell composed by several clumps\ndistributed around the HII region, suggesting that its expansion is collecting\nthe surrounding material. We find several YSO candidates over the molecular\nshell. Finally, comparing the HII region dynamical age and the fragmentation\ntime of the molecular shell, we discard the collect and collapse as the\nmechanism responsible for the YSOs formation, suggesting other processes such\nas radiative driven implosion and/or small-scale Jeans gravitational\ninstabilities.", "positive": "Evaporation Ages: a New Dating Method for Young Star Clusters: The ages of young star clusters are fundamental clocks to constrain the\nformation and evolution of pre-main-sequence stars and their protoplanetary\ndisks and exoplanets. However, dating methods for very young clusters often\ndisagree, casting doubts on the accuracy of the derived ages. We propose a new\nmethod to derive the kinematic age of star clusters based on the evaporation\nages of their stars. The method is validated and calibrated using hundreds of\nclusters identified in a supernova-driven simulation of the interstellar medium\nforming stars for approximately 40 Myr within a 250 pc region. We demonstrate\nthat the clusters' evaporation-age uncertainty can be as small as about 10% for\nclusters with a large enough number of evaporated stars and small but realistic\nobservational errors. We have obtained evaporation ages for a pilot sample of\n10 clusters, finding a good agreement with their published isochronal ages. The\nevaporation ages will provide important constraints for modeling the\npre-main-sequence evolution of low-mass stars, as well as to investigate the\nstar-formation and gas-evaporation history of young clusters. These ages can be\nmore accurate than isochronal ages for very young clusters, for which\nobservations and models are more uncertain." }, { "anchor": "Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active\n Nuclei in Massive Mergers: We present the results from a Chandra pilot study of 12 massive galaxy\nmergers selected from Galaxy Zoo. The sample includes major mergers down to a\nhost galaxy mass of 10$^{11}$ $M_\\odot$ that already have optical AGN\nsignatures in at least one of the progenitors. We find that the coincidences of\noptically selected active nuclei with mildly obscured ($N_H \\lesssim 1.1 \\times\n10^{22}$ cm$^{-2}$) X-ray nuclei are relatively common (8/12), but the\ndetections are too faint ($< 40$ counts per nucleus; $f_{2-10 keV} \\lesssim 1.2\n\\times 10^{-13}$ erg s$^{-1}$ cm$^{-2}$) to reliably separate starburst and\nnuclear activity as the origin of the X-ray emission. Only one merger is found\nto have confirmed binary X-ray nuclei, though the X-ray emission from its\nsouthern nucleus could be due solely to star formation. Thus, the occurrences\nof binary AGN in these mergers are rare (0-8%), unless most merger-induced\nactive nuclei are very heavily obscured or Compton thick.", "positive": "Kinematic groups across the MW disc: insights from models and from the\n RAVE catalogue: With the advent of the Gaia data, the unprecedented kinematic census of great\npart of the Milky Way disc will allow us to characterise the local kinematic\ngroups and new groups in different disc neighbourhoods. First, we show here\nthat the models predict a stellar kinematic response to the spiral arms and bar\nstrongly dependent on disc position. For example, we find that the kinematic\ngroups induced by the spiral arm models change significantly if one moves only\n~ 0.6 kpc in galactocentric radius, but ~ 2 kpc in azimuth. There are more and\nstronger groups as one approaches the spiral arms. Depending on the spiral\npattern speed, the kinematic imprints are more intense in nearby vicinities or\nfar from the Sun. Secondly, we present a preliminary study of the kinematic\ngroups observed by RAVE. This sample will allow us, for the first time, to\nstudy the dependence on Galactic position of the (thin and thick) disc moving\ngroups. In the solar neighbourhood, we find the same kinematics groups as\ndetected in previous surveys, but now with better statistics and over a larger\nspatial volume around the Sun. This indicates that these structures are indeed\nlarge scale kinematic features." }, { "anchor": "Brightest stars of irregular and low-massive spiral galaxies: A search for a correlation between the luminosities of the brightest stars\nand luminosities of their host galaxies was carried out on archived Hubble\nSpace Telescope (HST) F606W or F555W (V) and F814W (I) images of about 150\nnearby galaxies. The sample contains only galaxies with on-going star formation\n(SF) and with known distances we derived with the TRGB-method. We correlated\nthe average absolute luminosities of the three brightest blue and the three\nbrightest red stars with the luminosity of a host. We found a linear relation\nfor both the blue and the red stars in irregular and low-mass spiral galaxies.\nTheir scatters are sufficiently small (0.m4) to make this relations useful for\ndistance determination for low-mass galaxies. We found that all 31 dwarf\ngalaxies (M_B>-13m) in our sample lack bright stars (M_V(BS)< -7.m0), probably\ndue to the physical conditions that prevent their birth. For galaxies with\nhigher luminosity in the range -18m 10^10.5Msun)\ngalaxies, the density of the protocluster field increases to ~55 times the\ncontrol field density.", "positive": "Variability and parsec-scale radio structure of candidate compact\n symmetric objects: We report results on multi-epoch Very Large Array (VLA) and pc-scale Very\nLong Baseline Array (VLBA) observations of candidate compact symmetric objects\n(CSOs) from the faint sample of high frequency peakers. New VLBA observations\ncould resolve the radio structure in about 42 per cent of the observed sources,\nshowing double components that may be either mini-lobes or core-jet structures.\nAlmost all the sources monitored by the VLA show some variability on time scale\nof a decade, and only 1 source does not show any significant variation. In 17\nsources the flux density changes randomly as it is expected in blazars, and in\n4 sources the spectrum becomes flat in the last observing epoch, confirming\nthat samples selected in the GHz regime are highly contaminated by beamed\nobjects. In 16 objects, the pc-scale and variability properties are consistent\nwith a young radio source in adiabatic expansion, with a steady decrease of the\nflux density in the optically-thin part of the spectrum, and a flux density\nincrease in the optically-thick part. For these sources we estimate dynamical\nages between a few tens to a few hundreds years. The corresponding expansion\nvelocity is generally between 0.1c and 0.7c, similar to values found in CSOs\nwith different approaches. The fast evolution that we observe in some CSO\ncandidates suggests that not all the objects would become classical\nFanaroff-Riley radio sources." }, { "anchor": "Radiative transfer calculations of the diffuse ionised gas in disc\n galaxies with cosmic ray feedback: The large vertical scale heights of the diffuse ionised gas (DIG) in disc\ngalaxies are challenging to model, as hydrodynamical models including only\nthermal feedback seem to be unable to support gas at these heights. In this\npaper, we use a three dimensional Monte Carlo radiation transfer code to\npost-process disc simulations of the Simulating the Life-Cycle of Molecular\nClouds (SILCC) project that include feedback by cosmic rays. We show that the\nmore extended discs in simulations including cosmic ray feedback naturally lead\nto larger scale heights for the DIG which are more in line with observed scale\nheights. We also show that including a fiducial cosmic ray heating term in our\nmodel can help to increase the temperature as a function of disc scale height,\nbut fails to reproduce observed DIG nitrogen and sulphur forbidden line\nintensities. We show that, to reproduce these line emissions, we require a\nheating mechanism that affects gas over a larger density range than is achieved\nby cosmic ray heating, which can be achieved by fine tuning the total\nluminosity of ionising sources to get an appropriate ionising spectrum as a\nfunction of scale height. This result sheds a new light on the relation between\nforbidden line emissions and temperature profiles for realistic DIG gas\ndistributions.", "positive": "The velocity field of the Lyra complex: The formation of cosmic structure culminates with the assembly of galaxy\nclusters, a process quite different from cluster to cluster. We present the\nstudy of the structure and dynamics of the Lyra complex formed of the two\nclusters RXC J1825.3+3026 and CIZA J1824.1+3029, very recently studied using\nboth X-ray and radio data. This is the first analysis based on kinematics of\nmember galaxies. New spectroscopic data for 285 galaxies were acquired at the\nItalian Telescopio Nazionale Galileo and used in combination with PanSTARRS\nphotometry. The result of our member selection is a sample of 198 galaxies. For\nRXCJ1825 and CIZAJ1824 we report the redshifts, z=0.0645 and z=0.0708, the\nfirst estimates of velocity dispersion, sigmav=995 and 700 km/s, and dynamical\nmass, M200=1.1E15 and 4E14 Msun. The past assembly of RXCJ1825 is traced by the\ntwo dominant galaxies, both aligned with the major axis of the galaxy\ndistribution along the East-West direction, and by a minor North-East\nsubstructure. We also detect a quite peculiar high velocity field in the\nSouth-West region of the Lyra complex. This feature is likely related to a high\nvelocity, very luminous galaxy, suggested to be the central galaxy of a group\nin interaction with RXCJ1825 by very recent studies based on X-ray and radio\ndata. The redshift of the whole Lyra complex is z=0.067. Assuming that the\nredshift difference between RXCJ1825 and CIZAJ1824 is due to the relative\nkinematics, the projected distance between the cluster centers is 1.3 Mpc and\nthe los velocity difference is 1750 km/s. A dynamical analysis of the system\nshows that the two clusters are likely to be gravitationally bound, in a\npre-merger phase, with CIZAJ1824 in front of RXCJ1825 and going toward it. Our\nresults corroborate a picture where the Lyra region is the place of a very\ncomplex scenario of cluster assembly." }, { "anchor": "OB stars in the Leading Arm of the Magellanic Stream: We present our spectroscopic program aimed to study some new interesting\nfeatures recently discovered in the Magellanic Cloud System. These were\nrevealed by the spatial distribution of OB-type candidate stars, selected based\non UV, optical and IR photometry and proper motions from existing large-area\ncatalogs. As a pilot study of our project, we are studying OB-star candidates\nin the Leading Arm (LA) of the Magellanic Stream, a gaseous tidal structure\nwith no stellar counterpart known so far. Our targets group in three clumps\nnear regions of high HI density in the LA. If confirmed, these young stars\nwould evidence recent star formation in the LA, and they would help better\nunderstand and constrain the formation of the LA and its interactions with the\nMilky Way.", "positive": "No evidence for a dark matter disk within 4 kpc from the Galactic plane: We estimated the dynamical surface mass density (Sigma) at the solar\nGalactocentric distance between 2 and 4 kpc from the Galactic plane, as\ninferred from the observed kinematics of the thick disk. We find Sigma(z=2\nkpc)=57.6+-5.8 Mo pc^-2, and it shows only a tiny increase in the z-range\nconsidered by our investigation. We compared our results with the expectations\nfor the visible mass, adopting the most recent estimates in the literature for\ncontributions of the Galactic stellar disk and interstellar medium, and\nproposed models of the dark matter distribution. Our results match the\nexpectation for the visible mass alone, never differing from it by more than\n0.8 $Mo pc^-2 at any z, and thus we find little evidence for any dark\ncomponent. We assume that the dark halo could be undetectable with our method,\nbut the dark disk, recently proposed as a natural expectation of the LambdaCDM\nmodels, should be detected. Given the good agreement with the visible mass\nalone, models including a dark disk are less likely, but within errors its\nexistence cannot be excluded. In any case, these results put constraints on its\nproperties: thinner models (scale height lower than 4 kpc) reconcile better\nwith our results and, for any scale height, the lower-density models are\npreferred. We believe that successfully predicting the stellar thick disk\nproperties and a dark disk in agreement with our observations could be a\nchallenging theoretical task." }, { "anchor": "Improving Photometric Redshift Estimation using GPz: size information,\n post processing and improved photometry: The next generation of large scale imaging surveys (such as those conducted\nwith the Large Synoptic Survey Telescope and Euclid) will require accurate\nphotometric redshifts in order to optimally extract cosmological information.\nGaussian Processes for photometric redshift estimation (GPz) is a promising new\nmethod that has been proven to provide efficient, accurate photometric redshift\nestimations with reliable variance predictions. In this paper, we investigate a\nnumber of methods for improving the photometric redshift estimations obtained\nusing GPz (but which are also applicable to others). We use spectroscopy from\nthe Galaxy and Mass Assembly Data Release 2 with a limiting magnitude of r<19.4\nalong with corresponding Sloan Digital Sky Survey visible (ugriz) photometry\nand the UKIRT Infrared Deep Sky Survey Large Area Survey near-IR (YJHK)\nphotometry. We evaluate the effects of adding near-IR magnitudes and angular\nsize as features for the training, validation and testing of GPz and find that\nthese improve the accuracy of the results by ~15-20 per cent. In addition, we\nexplore a post-processing method of shifting the probability distributions of\nthe estimated redshifts based on their Quantile-Quantile plots and find that it\nimproves the bias by ~40 per cent. Finally, we investigate the effects of using\nmore precise photometry obtained from the Hyper Suprime-Cam Subaru Strategic\nProgram Data Release 1 and find that it produces significant improvements in\naccuracy, similar to the effect of including additional features.", "positive": "SDSS-IV MaStar: Theoretical Atmospheric Parameters for the MaNGA Stellar\n Library: We calculate the fundamental stellar parameters effective temperature,\nsurface gravity and iron abundance - T$_{\\rm eff}$, log g, [Fe/H] - for the\nfinal release of the Mapping Nearby Galaxies at APO (MaNGA) Stellar Library\n(MaStar), containing 59,266 per-visit-spectra for 24,290 unique stars at\nintermediate resolution ($R\\sim1800$) and high S/N (median = 96). We fit\ntheoretical spectra from model atmospheres by both MARCS and BOSZ-ATLAS9 to the\nobserved MaStar spectra, using the full spectral fitting code pPXF. We further\nemploy a Bayesian approach, using a Markov Chain Monte Carlo (MCMC) technique\nto map the parameter space and obtain uncertainties. Originally in this paper,\nwe cross match MaStar observations with Gaia photometry, which enable us to set\nreliable priors and identify outliers according to stellar evolution. In\nparallel to the parameter determination, we calculate corresponding stellar\npopulation models to test the reliability of the parameters for each stellar\nevolutionary phase. We further assess our procedure by determining parameters\nfor standard stars such as the Sun and Vega and by comparing our parameters\nwith those determined in the literature from high-resolution spectroscopy\n(APOGEE and SEGUE) and from lower-resolution matching template (LAMOST). The\ncomparisons, considering the different methodologies and S/N of the literature\nsurveys, are favourable in all cases. Our final parameter catalogue for MaStar\ncover the following ranges: $2592 \\leq $ T$_{\\rm eff} \\leq 32983\\;$K; $-0.7\n\\leq $ log g $ \\leq 5.4\\;$dex; $-2.9 \\leq $ [Fe/H] $\\leq 1.0\\;$dex and will be\navailable with the last SDSS-IV Data Release, in December 2021." }, { "anchor": "On the genesis of spiral galaxies -- Classical and pseudo bulges as\n extremities of a continuous sequence: A tantalizing enigma in extragalactic astronomy concerns the chronology and\ndriving mechanisms of the build-up of late-type galaxies (LTGs). The standard\nscenario envisages two formation routes, with classical bulges (CBs) assembling\nfirst in a quick quasi-monolithic episode followed by gradual disk assembly,\nand pseudo-bulges (PBs) forming over the Gyr-long secular evolution of LTGs.\nThe expectation is, therefore, the segregation of present-day LTG bulges into\ntwo distinct groups. Here we analyse the star formation histories (SFHs) of\nbulges and disks for 135 LTGs from the CALIFA survey covering the relevant\nrange in LTG mass. In addition, their physical properties were contrasted with\npredictions from evolutionary synthesis models, adopting exponentially\ndeclining SFHs, with an e-folding time 0.1 < $\\tau$ < 20 Gyr. Analysis of the\nSFHs of ~ half-million spaxels consistently reveals that the main properties of\nbulges and disks show a continuous distribution across total stellar mass.\nMoreover, the $\\tau$ in high-mass LTGs radially increases, suggesting that\nthese grow in an inside-out fashion, while lower-mass LTGs display roughly the\nsame $\\tau$ throughout their entire radial extent. Evolutionary synthesis\npredictions are consistent with observations. Finally, bulges and disks of\nhigher mass LTGs exhibit shorter formation timescales as compared to their\nlower mass counterparts. Collectively, the obtained results evince a coherent\nand unified picture for the formation and evolution of LTGs, in which PBs and\nCBs denote extremities of a continuous sequence. This analysis is consistent\nwith the framework where bulges are assembled with their parent disks by\ngradual inside-out growth, at a pace that is regulated by the depth of the\ngalactic potential. In accordance is the utter absence of bimodal correlations,\nas expected if CBs and PBs were to emerge from two distinct formation routes.", "positive": "Magnetically regulated collapse in the B335 protostar ? I. ALMA\n observations of the polarized dust emission: The role of the magnetic field during protostellar collapse is poorly\nconstrained from an observational point of view, although it could be\nsignificant if we believe state-of-the-art models of protostellar formation. We\npresent polarimetric observations of the 233 GHz thermal dust continuum\nemission obtained with ALMA in the B335 Class 0 protostar. Linearly polarized\ndust emission arising from the circumstellar material in the envelope of B335\nis detected at all scales probed by our observations, from radii of 50 to 1000\nau. The magnetic field structure producing the dust polarization has a very\nordered topology in the inner envelope, with a transition from a large-scale\npoloidal magnetic field, in the outflow direction, to strongly pinched in the\nequatorial direction. This is probably due to magnetic field lines being\ndragged along the dominating infall direction since B335 does not exhibit\nprominent rotation. Our data and their qualitative comparison to a family of\nmagnetized protostellar collapse models show that, during the magnetized\ncollapse in B335, the magnetic field is maintaining a high level of\norganization from scales 1000 au to 50 au: this suggests the field is\ndynamically relevant and capable of influencing the typical outcome of\nprotostellar collapse, such as regulating the disk size in B335." }, { "anchor": "The star formation rate cookbook at 1 < z < 3: Extinction-corrected\n relations for UV & [OII]\u03bb3727 luminosities: We use a spectroscopic sample of 286 star-forming galaxies (SFGs) at 1 4.5$ kpc) faint stars. Various tests show\nthat our method is capable of delivering atmospheric parameters with a\nprecision of $\\sim$80 K for $T_{\\rm eff}$, $\\sim$0.18 dex for [Fe/H] and\n$\\sim$0.35 dex for log $g$, but with a significant systematic error at log $g\n\\sim$ 2.3. For distances delivered from $(g-i)_0$ and photometric [Fe/H], our\ntest with the member stars of globular clusters show a median uncertainty of 16\nper cent with a negligible zero-point offset. Using this method, atmospheric\nparameters and distances of nearly one million red giant stars are derived from\nSMSS DR1.1. Proper motion measurements from Gaia DR2 are available for almost\nall of the red giant stars, and radial velocity measurements from several large\nspectroscopic surveys are available for 44 per cent of these. This sample will\nbe accessible online at https://yanghuang0.wixsite.com/yangh/research .", "positive": "Analytical theory for the initial mass function: II. Properties of the\n flow: Recently, Hennebelle and Chabrier (2008) derived an analytical theory for the\nmass spectrum of non self-gravitating clumps associated with overdensities in\nmolecular clouds and for the initial mass function of gravitationally bound\nprestellar cores, as produced by the turbulent collapse of the cloud. In this\ncompanion paper, we examine the effects of the non-isothermality of the flow,\nof the turbulence forcing and of local fluctuation of the velocity dispersion,\non the mass function. In particular, we investigate the influence of a\npolytropic equation of state and of the effective adiabatic exponent $\\gamma$\nand find that it has a drastic influence on the low mass part of the IMF. We\nalso consider a barotropic equation of state (i.e. a piecewise polytropic eos)\nthat mimics the thermal behaviour of the molecular gas and compare the\nprediction of our theory with the results of numerical simulations and with the\nobservationally-derived IMF, for cloud parameters which satisfy Larson's type\nrelations. We find that for clouds whose density is, at all scales, almost an\norder of magnitude larger than the density inferred for the CO clumps in the\nGalaxy, a good agreement is obtained between the theory and the observed IMF,\nsuggesting that star formation preferentially occurs in high density\nenvironments. We derive an analytical expression for the IMF which generalizes\nthe expression previously obtained for the isothermal case. This\neasy-to-implement analytical IMF should serve as a template to compare\nobservational or numerical results with the theory." }, { "anchor": "Modified Gravity and the Phantom of Dark Matter: Astrophysical data analysis of the weak-field predictions support the claim\nthat modified gravity (MOG) theories provide a self-consistent,\nscale-invariant, universal description of galaxy rotation curves, without the\nneed of non-baryonic dark matter. Comparison to the predictions of Milgrom's\nmodified dynamics (MOND) provide a best-fit and experimentally determined\nuniversal value of the MOND acceleration parameter. The predictions of the\nmodified gravity theories are compared to the predictions of cold non-baryonic\ndark matter (CDM), including a constant density core-modified fitting formula,\nwhich produces excellent fits to galaxy rotation curves including the low\nsurface brightness and dwarf galaxies.\n Upon analysing the mass profiles of clusters of galaxies inferred from X-ray\nluminosity measurements, from the smallest nearby clusters to the largest of\nthe clusters of galaxies, it is shown that while MOG provides consistent fits,\nMOND does not fit the observed shape of cluster mass profiles for any value of\nthe MOND acceleration parameter. Comparison to the predictions of CDM confirm\nthat whereas the Navarro-Frenk-White (NFW) fitting formula does not fit the\nobserved shape of galaxy cluster mass profiles, the core-modified dark matter\nfitting formula provides excellent best-fits, supporting the hypothesis that\nbaryons are dynamically important in the distribution of dark matter halos.", "positive": "Shattering of Cosmic Sheets due to Thermal Instabilities: a Formation\n Channel for Metal-Free Lyman Limit Systems: We present a new cosmological zoom-in simulation, where the zoom region\nconsists of two halos with virial mass M_v~5x10^{12}M_{sun} and a ~Mpc long\ncosmic filament connecting them at z~2. Using this simulation, we study the\nevolution of the intergalactic medium in between these two halos at\nunprecedented resolution. At 5>z>3, the two halos are found to lie in a large\nintergalactic sheet, or \"pancake\", consisting of multiple co-planar dense\nfilaments along which nearly all halos with M_v>10^9M_{sun} are located. This\nsheet collapses at z~5 from the merger of two smaller sheets. The strong shock\ngenerated by this merger leads to thermal instabilities in the post-shock\nregion, and to a shattering of the sheet resulting in <~kpc scale clouds with\ntemperatures of T>~2x10^4K and densities of n>~10^{-3}cm^{-3}, which are\npressure confined in a hot medium with T~10^6K and n>~10^{-5}cm^{-3}. When the\nsheet is viewed face on, these cold clouds have neutral hydrogen column\ndensities of N_{HI}>10^{17.2}cm^{-2}, making them detectable as Lyman limit\nsystems, though they lie well outside the virial radius of any halo and even\nwell outside the dense filaments. Their chemical composition is pristine,\nhaving zero metalicity, similar to several recently observed systems. Since\nthese systems form far from any galaxies, these results are robust to galaxy\nformation physics, resulting purely from the collapse of large scale structure\nand radiative cooling, provided sufficient spatial resolution is available." }, { "anchor": "Galaxy Mergers and the Mass-Metallicity Relation: Evidence for Nuclear\n Metal Dilution and Flattened Gradients from Numerical Simulations: Recent results comparing interacting galaxies to the mass-metallicity\nrelation show that their nuclear oxygen abundances are unexpectedly low. We\npresent analysis of N-body/SPH numerical simulations of equal-mass mergers that\nconfirm the hypothesis that these underabundances are accounted for by radial\ninflow of low-metallicity gas from the outskirts of the two merging galaxies.\nThe underabundances arise between first and second pericenter, and the\nsimulated abundance dilution is in good agreement with observations. The\nsimulations further predict that the radial metallicity gradients of the disk\ngalaxies flatten shortly after first passage, due to radial mixing of gas.\nThese predictions will be tested by future observations of the radial\nmetallicity distributions in interacting galaxies.", "positive": "Galaxies Probing Galaxies in PRIMUS - I. Sample, Spectroscopy, and\n Characteristics of the z~0.5 MgII-Absorbing Circumgalactic Medium: Spectroscopy of background QSO sightlines passing close to foreground\ngalaxies is a potent technique for studying the circumgalactic medium (CGM).\nQSOs are effectively point sources, however, limiting their potential to\nconstrain the size of circumgalactic gaseous structures. Here we present the\nfirst large Keck/LRIS and VLT/FORS2 spectroscopic survey of bright (B_AB <\n22.3) background galaxies whose lines of sight probe MgII 2796, 2803 absorption\nfrom the CGM around close projected foreground galaxies at transverse distances\n10 kpc < R_perp < 150 kpc. Our sample of 72 projected pairs, drawn from the\nPRIsm MUlti-object Survey (PRIMUS), includes 48 background galaxies which do\nnot host bright AGN, and both star-forming and quiescent foreground galaxies\nwith stellar masses 9.0 < log M_*/M_sun < 11.2 at redshifts 0.35 < z_f/g < 0.8.\nWe detect MgII absorption associated with these foreground galaxies with\nequivalent widths 0.25 Ang < W_2796 < 2.6 Ang at >2sigma significance in 20\nindividual background sightlines passing within R_perp < 50 kpc, and place\n2sigma upper limits on W_2796 of <0.5 Ang in an additional 11 close sightlines.\nWithin R_perp < 50 kpc, W_2796 is anticorrelated with R_perp, consistent with\nanalyses of MgII absorption detected along background QSO sightlines.\nSubsamples of these foreground hosts divided at log M_*/M_sun = 9.9 exhibit\nstatistically inconsistent W_2796 distributions at 30 kpc < R_perp < 50 kpc,\nwith the higher-M_* galaxies yielding a larger median W_2796 by 0.9 Ang.\nFinally, we demonstrate that foreground galaxies with similar stellar masses\nexhibit the same median W_2796 at a given R_perp to within <0.2 Ang toward both\nbackground galaxies and toward QSO sightlines drawn from the literature.\nAnalysis of these datasets constraining the spatial coherence scale of\ncircumgalactic MgII absorption is presented in a companion paper." }, { "anchor": "Systematic research of low redshift optically selected SDSS Type-2 AGN\n but with apparent long-term optical variabilities from Catalina Sky Survey,\n I: data sample and basic results: The main objective of the paper, the first paper in a dedicated series, is to\nreport basic results on systematic research of low-redshift optically selected\nSDSS Type-2 AGN but with apparent optical variabilities. For all the pipeline\nclassified Type-2 AGN in SDSS DR16 with $z<0.3$ and $SN>10$, long-term optical\nV-band light curves are collected from Catalina Sky Survey. Through all light\ncurves described by Damped Random Walk process with process parameters of\n$\\sigma/(mag/days^{0.5})$ and $\\tau/days$, 156 Type-2 AGN have apparent\nvariabilities with process parameters at least three times larger than\ncorresponding uncertainties and with $\\ln(\\sigma/(mag/days^{0.5}))>-4$,\nindicating central AGN activity regions directly in line-of-sight, leading the\n156 Type-2 AGN as mis-classified Type-2 AGN. Furthermore, based on\nspectroscopic emission features around H$\\alpha$, 31 out of the 156 AGN have\nbroad H$\\alpha$, indicating the 31 Type-2 AGN are actually Type-1.8/1.9 AGN.\nMeanwhile, 14 out of the 156 AGN have multi-epoch SDSS spectra. After checking\nmulti-epoch spectra of the 14 objects, no clues for appearance/disappearance of\nbroad lines indicate true Type-2 AGN rather than changing-look AGN are\npreferred in the collected Type-2 AGN with long-term variabilities. Moreover, a\nsmall sample of Type-2 AGN have long-term variabilities with features roughly\ndescribed by theoretical TDEs expected $t^{-5/3}$, indicating probable central\nTDEs as further and strong evidence to support true Type-2 AGN.", "positive": "Candidate high-z proto-clusters among the Planck compact sources, as\n revealed by Herschel-SPIRE: By determining the nature of all the Planck compact sources within 808.4\ndeg^2 of large Herschel surveys, we have identified 27 candidate proto-clusters\nof dusty star forming galaxies (DSFGs) that are at least 3{\\sigma} overdense in\neither 250, 350 or 500 $\\mu$mm sources. We find roughly half of all the Planck\ncompact sources are resolved by Herschel into multiple discrete objects, with\nthe other half remaining unresolved by Herschel. We find a significant\ndifference between versions of the Planck catalogues, with earlier releases\nhosting a larger fraction of candidate proto-clusters and Galactic Cirrus than\nlater releases, which we ascribe to a difference in the filters used in the\ncreation of the three catalogues. We find a surface density of DSFG candidate\nproto-clusters of (3.3 $\\pm$ 0.7) x 10^(-2) sources deg^(-2), in good agreement\nwith previous similar studies. We find that a Planck colour selection of\nS_{857}/S_{545} < 2 works well to select candidate proto-clusters, but can miss\nproto-clusters at z < 2. The Herschel colours of individual candidate\nproto-cluster members indicate our candidate proto-clusters all likely all lie\nat z > 1. Our candidate proto-clusters are a factor of 5 times brighter at 353\nGHz than expected from simulations, even in the most conservative estimates.\nFurther observations are needed to confirm whether these candidate\nproto-clusters are physical clusters, multiple proto-clusters along the line of\nsight, or chance alignments of unassociated sources." }, { "anchor": "Tracing accretion variability of high-mass YSOs via light echoes: There is growing evidence for disk-mediated accretion being the dominant mode\nof star formation across nearly the whole stellar mass spectrum. The stochastic\nnature of this process has been realized which implies an inherent source\nvariability. It can be traced more easily for low-mass YSOs (LMYSOs) since\nhigh-mass YSOs (HMYSOs) are still embedded even when reaching the ZAMS. While\nvariable reflection nebulae around LMYSOs were among the earliest signs of star\nformation, little is known on the variability of scattered light from embedded\nclusters, the birthplaces of HMYSOs. Since the few most massive stars dominate\nthis emission, their variability is literally reflected in scattered light.\nMoreover, because of their high luminosity, for a given ambient dust density\nand source distance, the associated nebulosities are much larger than those of\nLMYSOs. In this case, the light travel time becomes substantial. So the\napparent brightness distribution constitutes a light echo, shaped by both the\nHMYSO variability history and the spatial distribution of the scattering\nmedium. We report on early results of a NIR variability study of HMYSOs\nassociated with Class II methanol masers which aims at revealing a possible\ncorrelation between maser flux density and infrared brightness. Additionally,\nrelevant findings for the eruptive HMYSO S255IR-NIRS3 are presented.", "positive": "Spatially Resolved Magnetic Field Structure in the Disk of a T Tauri\n Star: Magnetic fields in accretion disks play a dominant role during the star\nformation process but have hitherto been observationally poorly constrained.\nField strengths have been inferred on T Tauri stars themselves and possibly in\nthe innermost part of the accretion disk, but the strength and morphology of\nthe field in the bulk of the disk have not been observed. Unresolved\nmeasurements of polarized emission (arising from elongated dust grains aligned\nperpendicular to the field) imply average fields aligned with the disks.\nTheoretically, the fields are expected to be largely toroidal, poloidal, or a\nmixture of the two, which imply different mechanisms for transporting angular\nmomentum in the disks of actively accreting young stars such as HL Tau. Here we\nreport resolved measurements of the polarized 1.25 mm continuum emission from\nHL Tau's disk. The magnetic field on a scale of 80 AU is coincident with the\nmajor axis (~210 AU diameter) of the disk. From this we conclude that the\nmagnetic field inside the disk at this scale cannot be dominated by a vertical\ncomponent, though a purely toroidal field does not fit the data well either.\nThe unexpected morphology suggests that the magnetic field's role for the\naccretion of a T Tauri star is more complex than the current theoretical\nunderstanding." }, { "anchor": "Red Clump Stars in the Sagittarius Tidal Streams: We have probed a section (l ~ 150, b ~ -60) of the trailing tidal arm of the\nSagittarius dwarf spheroidal galaxy by identifying a sample of Red Clump stream\nstars. Red Clump stars are not generally found in the halo field, but are found\nin significant numbers in both the Sagittarius galaxy and its tidal streams,\nmaking them excellent probes of stream characteristics. Our target sample was\nselected using photometric data from the Sloan Digital Sky Survey, Data Release\n6, which was constrained in color to match the Sagittarius Red Clump stars.\nSpectroscopic observations of the target stars were conducted at Kitt Peak\nNational Observatory using the WIYN telescope. The resulting spectroscopic\nsample is magnitude limited and contains both main sequence disk stars and\nevolved Red Clump stars. We have developed a method to systematically separate\nthese two stellar classes using kinematic information and a Bayesian approach\nfor surface gravity determination. The resulting Red Clump sample allows us to\ndetermine an absolute stellar density of {\\rho} = 2.7 +/- 0.5 RC stars kpc-3 at\nthis location in the stream. Future measurements of stellar densities for a\nvariety of populations and at various locations along the streams will lead to\na much improved understanding of the original nature of the Sagittarius galaxy\nand the physical processes controlling its disruption and subsequent stream\ngeneration.", "positive": "Multiple Populations in Integrated Light Spectroscopy of Intermediate\n Age Clusters: The presence of star-to-star light-element abundance variations (a.k.a.\nmultiple populations, MPs) appears to be ubiquitous within old and massive\nclusters in the Milky Way and all studied nearby galaxies. Most previous\nstudies have focussed on resolved images or spectroscopy of individual stars,\nalthough there has been significant effort in the past few years to look for\nmultiple population signatures in integrated light spectroscopy. If proven\nfeasible, integrated light studies offer a potential way to vastly open\nparameter space, as clusters out to tens of Mpc can be studied. We use the NaD\nlines in the integrated spectra of two clusters with similar ages ($2-3$ Gyr)\nbut very different masses, NGC 1978 ($\\sim3\\times10^5$ Msun) in the LMC and\nG114 ($1.7\\times10^7$ Msun) in NGC 1316. For NGC 1978, our findings agree with\nresolved studies of individual stars which did not find evidence for Na\nspreads. However, for G114, we find clear evidence for the presence of multiple\npopulations. The fact that the same anomalous abundance patterns are found in\nboth the intermediate age and ancient GCs lends further support to the notion\nthat young massive clusters are effectively the same as the ancient globular\nclusters, only separated in age." }, { "anchor": "On the chemical ladder of esters. Detection and formation of ethyl\n formate in the W51 e2 hot molecular core: The detection of organic molecules with increasing complexity and potential\nbiological relevance is opening the possibility to understand the formation of\nthe building blocks of life in the interstellar medium. One of the families of\nmolecules with astrobiological interest are the esters, whose simplest member,\nmethyl formate, is rather abundant in star-forming regions. The next step in\nthe chemical complexity of esters is ethyl formate, C$_2$H$_5$OCHO. Only two\ndetections of this species have been reported so far, which strongly limits our\nunderstanding of how complex molecules are formed in the interstellar medium.\nWe have searched for ethyl formate towards the W51 e2 hot molecular core, one\nof the most chemically rich sources in the Galaxy and one of the most promising\nregions to study prebiotic chemistry, especially after the recent discovery of\nthe P$-$O bond, key in the formation of DNA. We have analyzed a spectral line\nsurvey towards the W51 e2 hot molecular core, which covers 44 GHz in the 1, 2\nand 3 mm bands, carried out with the IRAM 30m telescope. We report the\ndetection of the trans and gauche conformers of ethyl formate. A Local\nThermodynamic Equilibrium analysis indicates that the excitation temperature is\n78$\\pm$10 K and that the two conformers have similar source-averaged column\ndensities of (2.0$\\pm$0.3)$\\times$10$^{16}$ cm$^{-2}$ and an abundance of\n$\\sim$10$^{-8}$. We compare the observed molecular abundances of ethyl formate\nwith different competing chemical models based on grain surface and gas-phase\nchemistry. We propose that grain-surface chemistry may have a dominant role in\nthe formation of ethyl formate (and other complex organic molecules) in hot\nmolecular cores, rather than reactions in the gas phase.", "positive": "Kinematical Fluctuations Vary with Galaxy Surface Mass Density: The Galaxy inner parts are generally considered to be optically symmetric, as\nwell as kinematically symmetric for most massive early-type galaxies. At the\nlower-mass end, many galaxies contain lots of small patches in their velocity\nmaps, causing their kinematics to be nonsmooth in small scales and far from\nsymmetry. These small patches can easily be mistaken for measurement\nuncertainties and have not been well discussed. We used the comparison of\nobservations and numerical simulations to demonstrate the small patches\nexistence beyond uncertainties. For the first time we have found that the\nfluctuation degrees have an approximate inverse loglinear relation with the\ngalaxy stellar surface mass densities. This tight relation among galaxies that\ndo not show obvious optical asymmetry that traces environmental perturbations\nindicates that stellar motion in galaxies has inherent asymmetry besides\nexternal environment influences. The degree of the kinetic asymmetry is closely\nrelated to and constrained by the intrinsic properties of the host galaxy." }, { "anchor": "Searching for Radio Outflows from M31* with VLBI Observations: As one of the nearest and most dormant supermassive black holes (SMBHs), M31*\nprovides a rare but promising opportunity for studying the physics of black\nhole accretion and feedback at the quiescent state. Previous Karl G. Jansky\nVery Large Array (VLA) observations with an arcsec resolution have detected\nM31* as a compact radio source over centimeter wavelengths, but the steep radio\nspectrum suggests optically-thin synchrotron radiation from an outflow driven\nby a hot accretion flow onto the SMBH. Aiming to probe the putative radio\noutflow, we have conducted milli-arcsec-resolution very long baseline\ninterferometric (VLBI) observations of M31* in 2016, primarily at 5 GHz and\ncombining the Very Long Baseline Array, Tianma-65m and Shanghai-25m Radio\nTelescopes. Despite the unprecedented simultaneous resolution and sensitivity\nachieved, no significant ($\\gtrsim 3\\sigma$) signal is detected at the putative\nposition of M31* given an RMS level of $\\rm 5.9~\\mu Jy\\ beam^{-1}$, thus ruling\nout a point-like source with a peak flux density comparable to that\n($\\sim30~\\mu Jy\\ beam^{-1}$) measured by the VLA observations taken in 2012. We\ndisfavor the possibility that M31* has substantially faded since 2012, in view\nthat a 2017 VLA observation successfully detected M31* at a historically-high\npeak flux density ($\\sim75~\\mu Jy\\ beam^{-1}$ at 6 GHz). Instead, the\nnon-detection of the VLBI observations is best interpreted as the arcsec-scale\ncore being resolved out at the milli-arcsec-scale, suggesting an intrinsic size\nof M31* at 5 GHz larger than $\\sim300$ times the Schwarzschild radius. Such\nextended radio emission may originate from a hot wind driven by the weakly\naccreting SMBH.", "positive": "Star formation in IC1396: Kinematics and subcluster structure revealed\n by Gaia: We investigate the star formation history of the IC1396 region by studying\nits kinematics and completing the population census. We use multiwavelength\ndata, combining optical spectroscopy (to identify and classify new members),\nnear-infrared photometry (to trace shocks, jets, and outflows and the\ninteractions between the cluster members and the cloud), along with Gaia EDR3\nto identify new potential members in the multidimensional proper\nmotion/parallax space. The revised Gaia EDR3 distance is 925$\\pm$73 pc,\nslightly closer than previously obtained with DR2. The Gaia data reveal four\ndistinct subclusters in the region. These subclusters are consistent in\ndistance but display differences in proper motion. This, with their age\ndifferences, hints towards a complex and varied star formation history. Gaia\ndata also unveil the intermediate-mass objects that tend to evade spectroscopic\nand disk surveys. Our analysis allows us to identify 334 new members. We\nestimate an average age of $\\sim$4 Myr, confirming previous age estimates. With\nthe new members added to our study, we estimate a disk fraction of 28\\%, lower\nthan previous values, due to our method detecting mainly new, diskless\nintermediate-mass stars. We find age differences between the subclusters, which\nevidences a complex star formation history with different episodes of star\nformation." }, { "anchor": "Search for cyclotron absorptions from magnetars in the quiescence with\n XMM-Newton: In this work, we perform the detailed analysis of absorption features in\nspectra of magnetar candidates observed by XMM-Newton satellite. No significant\nline-like feature has been found. This negative result may indicate the\npossible presence of smoothing out the absorption features mechanisms.", "positive": "Modeling of Galactic Foreground Polarization with Velocity Gradients: The detection of primordial B-mode polarization is still challenging due to\nthe relatively low amplitude compared to the galactic foregrounds. To remove\nthe contribution from the foreground, a comprehensive picture of the galactic\nmagnetic field is indispensable. The Velocity Gradient Technique (VGT) is\npromising in tracing magnetic fields based on the modern understanding of the\nmagneto-hydrodynamic turbulence. In this work, we apply VGT to a HI region\ncontaining an intermediate velocity cloud and a local velocity cloud, which are\ndistinguishable in position-position-velocity space. We show that VGT gives an\nexcellent agreement with the Planck polarization and stellar polarization. We\nconfirm the advantages of VGT in constructing the 3D galactic magnetic field." }, { "anchor": "Resilience of Sloshing Cold Fronts against Subsequent Minor Mergers: Minor mergers are common in galaxy clusters. They have the potential to\ncreate sloshing cold fronts (SCFs) in the intracluster medium (ICM) of the\ncluster. However, the resilience of SCFs to subsequent minor mergers is\nunknown. Here we investigate the extent to which SCFs established by an\noff-axis minor merger are disrupted by a subsequent minor merger. We perform a\nsuite of 13 hydrodynamic + N-body simulations of idealised triple cluster\nmergers in which we vary the approach direction and impact parameter of the\ntertiary cluster. Except for ~1 Gyr after the first core passage of the\ntertiary cluster, clear SCFs are present in all merger configurations.\nSubsequent head-on minor mergers reduce the number of SCFs significantly, while\nsubsequent off-axis minor mergers only moderately reduce the number of SCFs. In\nparticular, outer (>~500 kpc) SCFs are resilient. The results of this work\nindicate that SCFs are easily formed in the course of a minor merger and are\nlong-lived even if a further minor merger takes place. SCFs thus should be\nubiquitous, but deriving the merger history of a given cluster based on its\nobserved SCFs might be more complex than previously thought.", "positive": "Galaxy properties from J-PAS narrow-band photometry: We study the consistency of the physical properties of galaxies retrieved\nfrom SED-fitting as a function of spectral resolution and signal-to-noise ratio\n(SNR). Using a selection of physically motivated star formation histories, we\nset up a control sample of mock galaxy spectra representing observations of the\nlocal universe in high-resolution spectroscopy, and in 56 narrow-band and 5\nbroad-band photometry. We fit the SEDs at these spectral resolutions and\ncompute their corresponding the stellar mass, the mass- and luminosity-weighted\nage and metallicity, and the dust extinction. We study the biases,\ncorrelations, and degeneracies affecting the retrieved parameters and explore\nthe r\\^ole of the spectral resolution and the SNR in regulating these\ndegeneracies. We find that narrow-band photometry and spectroscopy yield\nsimilar trends in the physical properties derived, the former being\nconsiderably more precise. Using a galaxy sample from the SDSS, we compare more\nrealistically the results obtained from high-resolution and narrow-band SEDs\n(synthesized from the same SDSS spectra) following the same spectral fitting\nprocedures. We use results from the literature as a benchmark to our\nspectroscopic estimates and show that the prior PDFs, commonly adopted in\nparametric methods, may introduce biases not accounted for in a Bayesian\nframework. We conclude that narrow-band photometry yields the same trend in the\nage-metallicity relation in the literature, provided it is affected by the same\nbiases as spectroscopy; albeit the precision achieved with the latter is\ngenerally twice as large as with the narrow-band, at SNR values typical of the\ndifferent kinds of data." }, { "anchor": "Exploring the link between C IV outflow kinematics and\n sublimation-temperature dust in quasars: Using data from SDSS, UKIDSS and WISE, we investigate the properties of the\nhigh-frequency cutoff to the infrared emission in $\\simeq$5000 carefully\nselected luminous ($L_{bol} \\simeq 10^{47}$) type 1 quasars. The strength of\n$\\simeq$2 $\\mu$m emission, corresponding to emission from the hottest (T>1200K)\ndust in the sublimation zone surrounding the central continuum source, is\nobserved to correlate with the blueshift of the C IV $\\lambda$1550 emission\nline. We therefore find that objects with stronger signatures of nuclear\noutflows tend to have a larger covering fraction of sublimation-temperature\ndust. When controlling for the observed outflow strength, the hot dust covering\nfraction does not vary significantly across our sample as a function of\nluminosity, black hole mass or Eddington fraction. The correlation between the\nhot dust and the C IV line blueshifts, together with the lack of correlation\nbetween the hot dust and other parameters, therefore provides evidence of a\nlink between the properties of the broad emission line region and the\ninfrared-emitting dusty regions in quasars.", "positive": "The effect of spiral arms on the S\u00e9rsic photometry of galaxies: Context. The S\\'ersic profile is a widely-used model to describe the surface\nbrightness distribution of galaxies. Spiral galaxies, however, are\nqualitatively different from a S\\'ersic model.\n Aims. The goal of this study is to assess how accurately the total flux and\nhalf-light radius of a galaxy with spiral arms can be recovered when fitted\nwith a S\\'ersic profile.\n Methods. I selected a sample of bulge-dominated galaxies with spiral arms.\nUsing photometric data from the Hyper Suprime-Cam survey, I estimated the\ncontribution of the spiral arms to their total flux. Then I generated simulated\nimages of galaxies with similar characteristics, fitted them with a S\\'ersic\nmodel, and quantified the error on the determination of the total flux and\nhalf-light radius.\n Results. Spiral arms can introduce biases on the photometry of galaxies in a\nway that depends on the underlying smooth surface brightness profile, the\nlocation of the arms, and the depth of the photometric data. A set of spiral\narms accounting for 10% of the flux of a bulge-dominated galaxy typically\ncauses the total flux and the half-light radius to be overestimated by 15% and\n30%, respectively. This bias, however, is much smaller if the galaxy is\ndisk-dominated.\n Conclusions. Galaxies with a prominent bulge and a non-zero contribution from\nspiral arms are the most susceptible to biases in the total flux and half-light\nradius, when fitted with a S\\'ersic profile. If photometric measurements with\nhigh accuracy are required, then measurements over finite apertures are to be\npreferred over global estimates of the flux." }, { "anchor": "The integrated properties of the CALIFA galaxies: Model-derived galaxy\n parameters and quenching of star formation: We present a study of the integrated properties of the 835 galaxies in the\nCALIFA survey. To derive the main physical parameters of the galaxies we have\nfitted their UV-to-IR spectral energy distributions (SED) with sets of\ntheoretical models using CIGALE. We perform a comparison of the integrated\ngalaxy parameters derived from multi-band SED fitting with those obtained from\nmodelling the Integral Field Unit (IFU) spectra and show the clear advantage of\nusing the SED-derived star formation rates (SFR). A detailed analysis of\ngalaxies in the SFR/Mstar plane as a function of their properties reveals that\nquenching of star formation is caused by a combination of gas deficiency and\nthe inefficiency of the existing gas to form new stars. Exploring the plausible\nmechanisms that could produce this effect, we find a strong correlation with\ngalaxy morphology and the build-up of central bulge. On the other hand, the\npresence of AGN and/or a stellar bar, as well as the local environment have\nonly temporal effects on the current star formation, a result also consistent\nwith their model-derived star formation histories.", "positive": "Magnetic field strength from turbulence theory (I): Using differential\n measure approach (DMA): The mean plane-of-sky magnetic field strength is traditionally obtained from\nthe combination of polarization and spectroscopic data using the\nDavis-Chandrasekhar-Fermi (DCF) technique. However, we identify the major\nproblem of the DCF to be its disregard of the anisotropic character of MHD\nturbulence. On the basis of the modern MHD turbulence theory we introduce a new\nway of obtaining magnetic field strength from observations. Unlike the DCF, the\nnew technique uses not the dispersion of the polarization angle and line of\nsight velocities, but increments of these quantities given by the structure\nfunctions. To address the variety of the astrophysical conditions for which our\ntechnique can be applied, we consider the turbulence in both media with\nmagnetic pressure larger than the gas pressure corresponding e.g. to molecular\nand the gas pressure larger than the magnetic pressure corresponding to the\nwarm neutral medium. We provide general expressions for arbitrary admixture of\nAlfv\\'en, slow and fast modes in these media and consider in detail the\nparticular cases relevant to diffuse media and molecular clouds. We\nsuccessfully test our results using synthetic observations obtained from MHD\nturbulence simulations. We demonstrate that our Differential Measure Approach\n(DMA), unlike the DCF, can be used to measure the distribution of magnetic\nfield strengths, can provide magnetic field measurements with limited data and\nis much more stable in the presence of large scale variations induces of\nnon-turbulent nature. In parallel, our study uncover the deficiencies of the\nearlier DCF research." }, { "anchor": "The VLT LBG Redshift Survey - VI. Mapping HI in the proximity of\n $z\\sim3$ LBGs with X-Shooter: We present an analysis of the spatial distribution of gas and galaxies using\nnew X-Shooter observations of $z\\sim3-4$ quasars. Adding the X-Shooter data to\nan existing dataset of high resolution quasar spectroscopy, we use a total\nsample of 29 quasars alongside $\\sim1700$ Lyman Break Galaxies in the redshift\nrange $2 500 km/s, this bring the total number of massive LSB\ngalaxies to 41. There are no obvious trends between the various measured global\ngalaxy properties, particularly between mean surface brightness and galaxy\nmass.", "positive": "Australia Telescope Compact Array Radio Continuum 1384 and 2368 Mhz\n Observations of Sagittarius B: We present images of the Sagittarius (Sgr) B giant molecular cloud at 2368\nand 1384 MHz obtained using new, multi-configuration Australia Telescope\nCompact Array (ATCA) observations. We have combined these observations with\narchival single-dish observations yielding images at resolutions of 47\" by 14\"\nand 27\" by 8\" at 1384 and 2368 MHz respectively. These observations were\nmotivated by our theoretical work (Protheroe et al. 2008) indicating the\npossibility that synchrotron emission from secondary electrons and positrons\ncreated in hadronic cosmic ray (CR) collisions with the ambient matter of the\nSgr B2 cloud could provide a detectable (and possibly linearly polarized)\nnon-thermal radio signal. We find that the only detectable non-thermal emission\nfrom the Sgr B region is from a strong source to the south of Sgr B2, which we\nlabel Sgr B2 Southern Complex (SC). We find Sgr B2(SC) integrated flux\ndensities of 1.2+/-0.2 Jy at 1384 MHz and 0.7+/-0.1 Jy at 2368 MHz for a source\nof FWHM size at 1384 MHz of ~54\". Despite its non-thermal nature, the\nsynchrotron emission from this source is unlikely to be dominantly due to\nsecondary electrons and positrons. We use polarization data to place 5-sigma\nupper limits on the level of polarized intensity from the Sgr B2 cloud of 3.5\nand 3 mJy/beam at 1384 and 2368 MHz respectively. We also use the angular\ndistribution of the total intensity of archival 330 MHz VLA and the total\nintensity and polarized emission of our new 1384 MHz and 2368 MHz data to\nconstrain the diffusion coefficient for transport of the parent hadronic CRs\ninto the dense core of Sgr B2 to be no larger than about 1% of that in the\nGalactic disk. Finally, we have also used the data to perform a spectral and\nmorphological study of the features of the Sgr B cloud and compare and contrast\nthese to previous studies." }, { "anchor": "Dust-Enshrouded AGN can Dominate Host-Galaxy-Scale Cold-Dust Emission: It is widely assumed that long-wavelength infrared (IR) emission from cold\ndust (T~20-40K) is a reliable tracer of star formation even in the presence of\na bright active galactic nucleus (AGN). Based on radiative transfer (RT) models\nof clumpy AGN tori, hot dust emission from the torus contributes negligibly to\nthe galaxy spectral energy distribution (SED) at $\\lambda\\ga100$ \\micron.\nHowever, these models do not include AGN heating of host-galaxy-scale diffuse\ndust, which may have far-IR (FIR) colors comparable to cold diffuse dust heated\nby stars. To quantify the contribution of AGN heating to host-galaxy-scale cold\ndust emission at $\\lambda\\ga100$ \\micron, we perform dust RT calculations on a\nsimulated galaxy merger both including and excluding the bright AGN that it\nhosts. By differencing the SEDs yielded by RT calculations with and without AGN\nthat are otherwise identical, we quantify the FIR cold dust emission arising\nsolely from re-processed AGN photons. In extreme cases, AGN-heated\nhost-galaxy-scale dust can increase galaxy-integrated FIR flux densities by\nfactors of 2-4; star formation rates calculated from the FIR luminosity\nassuming no AGN contribution can overestimate the true value by comparable\nfactors. Because the FIR colors of such systems are similar to those of purely\nstar-forming galaxies and redder than torus models, broadband SED decomposition\nmay be insufficient for disentangling the contributions of stars and heavily\ndust-enshrouded AGN in the most IR-luminous galaxies. We demonstrate how\nkpc-scale resolved observations can be used to identify deeply dust-enshrouded\nAGN with cool FIR colors when spectroscopic and/or X-ray detection methods are\nunavailable.", "positive": "Micro-arcsecond structure of Sagittarius A* revealed by high-sensitivity\n 86 GHz VLBI observations: The compact radio source Sagittarius~A$^*$ (Sgr~A$^*$)in the Galactic Center\nis the primary supermassive black hole candidate. General relativistic\nmagnetohydrodynamical (GRMHD) simulations of the accretion flow around\nSgr\\,A$^*$ predict the presence of sub-structure at observing wavelengths of\n$\\sim 3$\\,mm and below (frequencies of 86\\,GHz and above). For very long\nbaseline interferometry (VLBI) observations of Sgr\\,A$^*$ at this frequency the\nblurring effect of interstellar scattering becomes subdominant, and arrays such\nas the High Sensitivity Array (HSA) and the global mm-VLBI Array (GMVA) are now\ncapable of resolving potential sub-structure in the source. Such investigations\nimprove our understanding of the emission geometry of the mm-wave emission of\nSgr\\,A$^*$, which is crucial for constraining theoretical models and for\nproviding a background to interpret 1\\,mm VLBI data from the Event Horizon\nTelescope (EHT). We performed high-sensitivity very long baseline\ninterferometry (VLBI) observations of Sgr\\,A$^*$ at 3\\,mm using the Very Long\nBaseline Array (VLBA) and the Large Millimeter Telescope (LMT) in Mexico on two\nconsecutive days in May 2015, with the second epoch including the Green Bank\nTelescope (GBT). We find an overall source geometry that matches previous\nfindings very closely, showing a deviation in fitted model parameters less than\n3\\% over a time scale of weeks and suggesting a highly stable global source\ngeometry over time. The reported sub-structure in the 3\\,mm emission of\nSgr\\,A$^*$ is consistent with theoretical expectations of refractive noise on\nlong baselines. However, comparing our findings with recent results from 1\\,mm\nand 7\\,mm VLBI observations, which also show evidence for east-west asymmetry,\nan intrinsic origin cannot be excluded. Confirmation of persistent intrinsic\nsubstructure will require further VLBI observations spread out over multiple\nepochs." }, { "anchor": "The missing radial velocities of Gaia: a catalogue of Bayesian estimates\n for DR3: In an earlier work, we demonstrated the effectiveness of Bayesian neural\nnetworks in estimating the missing line-of-sight velocities of Gaia stars, and\npublished an accompanying catalogue of blind predictions for the line-of-sight\nvelocities of stars in Gaia DR3. These were not merely point predictions, but\nprobability distributions reflecting our state of knowledge about each star.\nHere, we verify that these predictions were highly accurate: the DR3\nmeasurements were statistically consistent with our prediction distributions,\nwith an approximate error rate of 1.5%. We use this same technique to produce a\npublicly available catalogue of predictive probability distributions for the\n185 million stars up to a G-band magnitude of 17.5 still missing line-of-sight\nvelocities in Gaia DR3. Validation tests demonstrate that the predictions are\nreliable for stars within approximately 7 kpc from the Sun and with distance\nprecisions better than around 20%. For such stars, the typical prediction\nuncertainty is 25-30 km/s. We invite the community to use these radial\nvelocities in analyses of stellar kinematics and dynamics, and give an example\nof such an application.", "positive": "The MUSE view of He 2-10: no AGN ionization but a sparkling starburst: We study the physical and dynamical properties of the ionized gas in the\nprototypical HII galaxy Henize 2-10 using MUSE integral field spectroscopy. The\nlarge scale dynamics is dominated by extended outflowing bubbles, probably the\nresults of massive gas ejection from the central star forming regions. We\nderive a mass outflow rate dMout/dt~0.30 Msun/yr, corresponding to mass loading\nfactor eta~0.4, in range with similar measurements in local LIRGs. Such a\nmassive outflow has a total kinetic energy that is sustainable by the stellar\nwinds and Supernova Remnants expected in the galaxy. We use classical emission\nline diagnostic to study the dust extinction, electron density and ionization\nconditions all across the galaxy, confirming the extreme nature of the highly\nstar forming knots in the core of the galaxy, which show high density and high\nionization parameter. We measure the gas phase metallicity in the galaxy taking\ninto account the strong variation of the ionization parameter, finding that the\nexternal parts of the galaxy have abundances as low as 12 + log(O/H)~8.3, while\nthe central star forming knots are highly enriched with super solar\nmetallicity. We find no sign of AGN ionization in the galaxy, despite the\nrecent claim of the presence of a super massive active Black Hole in the core\nof He~2-10. We therefore reanalyze the X-ray data that were used to propose the\npresence of the AGN, but we conclude that the observed X-ray emission can be\nbetter explained with sources of a different nature, such as a Supernova\nRemnant." }, { "anchor": "Neutral hydrogen in galaxy halos at the peak of the cosmic star\n formation history: We use high-resolution cosmological zoom-in simulations from the FIRE project\nto make predictions for the covering fractions of neutral hydrogen around\ngalaxies at z=2-4. These simulations resolve the interstellar medium of\ngalaxies and explicitly implement a comprehensive set of stellar feedback\nmechanisms. Our simulation sample consists of 16 main halos covering the mass\nrange M_h~10^9-6x10^12 Msun at z=2, including 12 halos in the mass range\nM_h~10^11-10^12 Msun corresponding to Lyman break galaxies (LBGs). We process\nour simulations with a ray tracing method to compute the ionization state of\nthe gas. Galactic winds increase the HI covering fractions in galaxy halos by\ndirect ejection of cool gas from galaxies and through interactions with gas\ninflowing from the intergalactic medium. Our simulations predict HI covering\nfractions for Lyman limit systems (LLSs) consistent with measurements around\nz~2-2.5 LBGs; these covering fractions are a factor ~2 higher than our previous\ncalculations without galactic winds. The fractions of HI absorbers arising in\ninflows and in outflows are on average ~50% but exhibit significant time\nvariability, ranging from ~10% to ~90%. For our most massive halos, we find a\nfactor ~3 deficit in the LLS covering fraction relative to what is measured\naround quasars at z~2, suggesting that the presence of a quasar may affect the\nproperties of halo gas on ~100 kpc scales. The predicted covering fractions,\nwhich decrease with time, peak at M_h~10^11-10^12 Msun, near the peak of the\nstar formation efficiency in dark matter halos. In our simulations, star\nformation and galactic outflows are highly time dependent; HI covering\nfractions are also time variable but less so because they represent averages\nover large areas.", "positive": "Dependence of the Star Formation Efficiency on the Parameters of\n Molecular Cloud Formation Simulations: We investigate the response of the star formation efficiency (SFE) to the\nmain parameters of simulations of molecular cloud formation by the collision of\nwarm diffuse medium (WNM) cylindrical streams, neglecting stellar feedback and\nmagnetic fields. The parameters we vary are the Mach number of the inflow\nvelocity of the streams, Msinf, the rms Mach number of the initial background\nturbulence in the WNM, and the total mass contained in the colliding gas\nstreams, Minf. Because the SFE is a function of time, we define two estimators\nfor it, the \"absolute\" SFE, measured at t = 25 Myr into the simulation's\nevolution (sfeabs), and the \"relative\" SFE, measured 5 Myr after the onset of\nstar formation in each simulation (sferel). The latter is close to the \"star\nformation rate per free-fall time\" for gas at n = 100 cm^-3. We find that both\nestimators decrease with increasing Minf, although by no more than a factor of\n2 as Msinf increases from 1.25 to 3.5. Increasing levels of background\nturbulence similarly reduce the SFE, because the turbulence disrupts the\ncoherence of the colliding streams, fragmenting the cloud, and producing\nsmall-scale clumps scattered through the numerical box, which have low SFEs.\nFinally, the SFE is very sensitive to the mass of the inflows, with sferel\ndecreasing from ~0.4 to ~0.04 as the the virial parameter in the colliding\nstreams increases from ~0.15 to ~1.5. This trend is in partial agreement with\nthe prediction by Krumholz & McKee (2005), since the latter lies within the\nsame range as the observed efficiencies, but with a significantly shallower\nslope. We conclude that the observed variability of the SFE is a highly\nsensitive function of the parameters of the cloud formation process, and may be\nthe cause of significant scatter in observational determinations." }, { "anchor": "A SITELLE view of M31's central region - I: Calibrations and radial\n velocity catalogue of nearly 800 emission-line point-like sources: We present a detailed description of the wavelength, astrometric and\nphotometric calibration plan for SITELLE, the imaging Fourier transform\nspectrometer attached to the Canada-France-Hawaii telescope, based on\nobservations of a red (647 - 685 nm) data cube of the central region (11$'\n\\times 11'$) of the Andromeda galaxy. The first application, presented in this\npaper, is a radial-velocity catalogue (with uncertainties of $\\sim 2 - 6$ km/s)\nof nearly 800 emission-line point-like sources, including $\\sim$ 450 new\ndiscoveries. Most of the sources are likely planetary nebulae, although we also\ndetect five novae (having erupted in the first 8 months of 2016) and one new\nsupernova remnant candidate.", "positive": "An Empirical Relation Between The Large-Scale Magnetic Field And The\n Dynamical Mass In Galaxies: The origin and evolution of cosmic magnetic fields as well as the influence\nof the magnetic fields on the evolution of galaxies are unknown. Though not\nwithout challenges, the dynamo theory can explain the large-scale coherent\nmagnetic fields which govern galaxies, but observational evidence for the\ntheory is so far very scarce. Putting together the available data of\nnon-interacting, non-cluster galaxies with known large-scale magnetic fields,\nwe find a tight correlation between the integrated polarized flux density,\nS(PI), and the rotation speed, v(rot), of galaxies. This leads to an almost\nlinear correlation between the large-scale magnetic field B and v(rot),\nassuming that the number of cosmic ray electrons is proportional to the star\nformation rate, and a super-linear correlation assuming equipartition between\nmagnetic fields and cosmic rays. This correlation cannot be attributed to an\nactive linear alpha-Omega dynamo, as no correlation holds with global shear or\nangular speed. It indicates instead a coupling between the large-scale magnetic\nfield and the dynamical mass of the galaxies, B ~ M^(0.25-0.4). Hence, faster\nrotating and/or more massive galaxies have stronger large-scale magnetic\nfields. The observed B-v(rot) correlation shows that the anisotropic turbulent\nmagnetic field dominates B in fast rotating galaxies as the turbulent magnetic\nfield, coupled with gas, is enhanced and ordered due to the strong gas\ncompression and/or local shear in these systems. This study supports an\nstationary condition for the large-scale magnetic field as long as the\ndynamical mass of galaxies is constant." }, { "anchor": "Galaxies at the extremes: Ultra-diffuse galaxies in the Virgo Cluster: We report the discovery of three large (R29 >~ 1 arcminute) extremely low\nsurface brightness (mu_(V,0) ~ 27.0) galaxies identified using our deep,\nwide-field imaging of the Virgo Cluster from the Burrell Schmidt telescope.\nComplementary data from the Next Generation Virgo Cluster Survey do not resolve\nred giant branch stars in these objects down to i=24, yielding a lower distance\nlimit of 2.5 Mpc. At the Virgo distance, these objects have half-light radii\n3-10 kpc and luminosities L_V=2-9x10^7 Lsun. These galaxies are comparable in\nsize but lower in surface brightness than the large ultradiffuse LSB galaxies\nrecently identified in the Coma cluster, and are located well within Virgo's\nvirial radius; two are projected directly on the cluster core. One object\nappears to be a nucleated LSB in the process of being tidally stripped to form\na new Virgo ultracompact dwarf galaxy. The others show no sign of tidal\ndisruption, despite the fact that such objects should be most vulnerable to\ntidal destruction in the cluster environment. The relative proximity of Virgo\nmakes these objects amenable to detailed studies of their structural properties\nand stellar populations. They thus provide an important new window onto the\nconnection between cluster environment and galaxy evolution at the extremes.", "positive": "Neutron star natal kicks and the long-term survival of star clusters: We investigate the dynamical evolution of a star cluster in an external tidal\nfield by using N-body simulations, with focus on the effects of the presence or\nabsence of neutron star natal velocity kicks.We show that, even if neutron\nstars typically represent less than 2% of the total bound mass of a star\ncluster, their primordial kinematic properties may affect the lifetime of the\nsystem by up to almost a factor of four. We interpret this result in the light\nof two known modes of star cluster dissolution, dominated by either early\nstellar evolution mass loss or two-body relaxation. The competition between\nthese effects shapes the mass loss profile of star clusters, which may either\ndissolve abruptly (\"jumping\"), in the pre-core-collapse phase, or gradually\n(\"skiing\"), after having reached core collapse." }, { "anchor": "Constraining the origin and models of chemical enrichment in galaxy\n clusters using the Athena X-IFU: The chemical enrichment of the Universe at all scales is related to stellar\nwinds and explosive supernovae phenomena. Metals produced by stars and later\nspread at the mega-parsec scale through the intra-cluster medium (ICM) become a\nfossil record of the chemical enrichment of the Universe and of the dynamical\nand feedback mechanisms determining their circulation. As demonstrated by the\nresults of the soft X-ray spectrometer onboard Hitomi, high resolution X-ray\nspectroscopy is the path to to differentiate among the models that consider\ndifferent metal production mechanisms, predict the outcoming yields, and are\nfunction of the nature, mass, and/or initial metallicity of their stellar\nprogenitor. Transformational results shall be achieved through improvements in\nthe energy resolution and effective area of X-ray observatories to detect rare\nmetals (e.g. Na, Al) and constrain yet uncertain abundances (e.g. C, Ne, Ca,\nNi). The X-ray Integral Field Unit (X-IFU) instrument onboard the\nnext-generation European X-ray observatory Athena is expected to deliver such\nbreakthroughs. Starting from 100 ks of synthetic observations of 12 abundance\nratios in the ICM of four simulated clusters, we demonstrate that the X-IFU\nwill be capable of recovering the input chemical enrichment models at both low\n($z = 0.1$) and high ($z = 1$) redshifts, while statistically excluding more\nthan 99.5% of all the other tested combinations of models. By fixing the\nenrichment models which provide the best fit to the simulated data, we also\nshow that the X-IFU will constrain the slope of the stellar initial mass\nfunction within $\\sim$12%. These constraints will be key ingredients in our\nunderstanding of the chemical enrichment of the Universe and its evolution.", "positive": "IFUs surveys, a panoramic view of galaxy evolution: We present here a brief summary of the currenly on-going IFU surveys of\ngalaxies in the Local Universe, describing their main characteristics,\nincluding their sample selections, instrumental setups, wavelength ranges, and\narea of the galaxies covered. Finally, we make an emphasis on the main\ncharacteristics of the CALIFA survey and the more recent results that has been\nrecently published" }, { "anchor": "Dynamics of Stellar Disk Tilting from Satellite Mergers: The Milky Way's stellar disk can tilt in response to torques that result from\ninfalling satellite galaxies and their associated tidal debris. In this work,\nwe explore the dynamics of disk tilting by running N-body simulations of\nmergers in an isolated, isotropic Milky Way-like host galaxy, varying over\nsatellite virial mass, initial position, and orbit. We develop and validate a\nfirst-principles understanding of the dynamics that govern how the host\ngalaxy's stellar disk responds to the satellite's dark matter debris. We find\nthat the degree of disk tilting can be large for cosmologically-motivated\nmerger histories. In particular, our results suggest that the Galactic disk may\nstill be tilting in response to Gaia-Sausage-Enceladus, one of the most\nsignificant recent mergers in the Milky Way's history. These findings have\nimplications for terrestrial direct detection experiments as disk tilting\nchanges the relative location of the Sun with respect to dark matter\nsubstructure left behind by a merging galaxy.", "positive": "Systematically Asymmetric: A comparison of \\hi\\ profile asymmetries in\n real and simulated galaxies: We examine different measures of asymmetry for galaxy HI velocity profiles.\nWe introduce the channel-by-channel asymmetry and the velocity-of-equality\nstatistics to quantify profile asymmetries. Using a sample of simulated\ngalaxies, we examine how these and the standard lopsidedness morphometric\nstatistic depend on a variety of observational effects including the viewing\nangle and inclination. We find that our newly introduced channel-by-channel\nasymmetry is less sensitive to the effects of viewing angle and inclination\nthan other morphometrics. Applying our statistics to the WHISP HI galaxy\nsample, we also find that the channel-by-channel asymmetry, is a better\nindicator of visually-classified asymmetric profiles. In addition, we find that\nthe lopsidedness-velocity of equality space can be used to identify profiles\nwith deep central dips without visual inspection." }, { "anchor": "Observational Evidence Linking Interstellar UV Absorption to PAH\n Molecules: The 2175 \\AA\\ UV extinction feature was discovered in the mid-1960s, yet its\nphysical origin remains poorly understood. One suggestion is absorption by\nPolycyclic Aromatic Hydrocarbons (PAH) molecules, which is supported by\ntheoretical molecular structure computations and by laboratory experiments.\nPAHs are positively detected by their 3.3, 6.2, 7.7 8.6, 11.3 & 12.7 $\\mu$m IR\nemission bands, which are specified by their modes of vibration. A definitive\nempirical link between the 2175 \\AA\\ UV extinction, and the PAH IR emission\nbands, however, is still missing. We present a new sample of hot stars that\nhave both 2175 \\AA\\ absorption and PAH IR emission. We find significant shifts\nof the central wavelength of the UV absorption feature, up to 2350 \\AA, but\npredominantly in stars that also have IR PAH emission. These UV shifts depend\non stellar temperature in a fashion that is similar to the shifts of the 6.2\nand 7.7$\\mu$m PAH IR bands, namely the features are increasingly more\nred-shifted as the stellar temperature decreases, but only below $\\sim 15$ kK.\nAbove 15 kK both UV and IR features retain their nominal values. Moreover, we\nfind a suggestive correlation between the UV and IR shifts. We hypothesize that\nthese similar dependences of both the UV and IR features on stellar temperature\nhint to a common origin of the two in PAH molecules and may establish the\nmissing link between the UV and IR observations. We further suggest that the\nshifts depend on molecular size, and that the critical temperature of $\\sim 15$\nkK above which no shifts are observed is related to the onset of UV driven\nhot-star winds and their associated shocks.", "positive": "Texas Spectroscopic Search for Ly$\u03b1$ Emission at the End of\n Reionization I. Constraining the Ly$\u03b1$ Equivalent Width Distribution at\n 6.0 < $z$ < 7.0: The distribution of Ly$\\alpha$ emission is an presently accessible method for\nstudying the state of the intergalactic medium (IGM) into the reionization era.\nWe carried out deep spectroscopic observations in order to search for\nLy$\\alpha$ emission from galaxies with photometric redshifts $z$ = 5.5 - 8.3\nselected from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy\nSurvey (CANDELS). Utilizing data from the Keck/DEIMOS spectrograph, we explore\na wavelength coverage of Ly$\\alpha$ emission at $z$ ~ 5 - 7 with four nights of\nspectroscopic observations for 118 galaxies, detecting five emission lines with\n~ 5$\\sigma$ significance: three in the GOODS-N and two in the GOODS-S field. We\nconstrain the equivalent width (EW) distribution of Ly$\\alpha$ emission by\ncomparing the number of detected objects with the expected number constructed\nfrom detailed simulations of mock emission lines that account for the\nobservational conditions (e.g., exposure time, wavelength coverage, and sky\nemission) and galaxy photometric redshift probability distribution functions.\nThe Ly$\\alpha$ EW distribution is well described by an exponential form,\n$\\text{dN/dEW}\\propto \\text{exp(-EW/}W_0)$, characterized by the $e$-folding\nscale ($W_0$) of ~ 60 - 100$\\AA$ at 0.3 < $z$ < 6. By contrast, our measure of\nthe Ly$\\alpha$ EW distribution at 6.0 < $z$ < 7.0 rejects a Ly$\\alpha$ EW\ndistribution with $W_0$ > 36.4$\\AA$ (125.3$\\AA$) at 1$\\sigma$ (2$\\sigma$)\nsignificance. This provides additional evidence that the EW distribution of\nLy$\\alpha$ declines at $z$ > 6, suggesting an increasing fraction of neutral\nhydrogen in the IGM at that epoch." }, { "anchor": "Molecular Gas Outflow in the Starburst Galaxy NGC 1482: Galactic winds are essential to regulation of star formation in galaxies. To\nstudy the distribution and dynamics of molecular gas in a wind, we imaged the\nnearby starburst galaxy NGC 1482 in CO ($J=1\\rightarrow0$) at a resolution of\n1'' ($\\approx100$ pc) using the Atacama Large Millimeter/submillimeter Array.\nMolecular gas is detected in a nearly edge-on disk with a radius of 3 kpc and a\nbiconical outflow emerging from the central 1 kpc starburst and extending to at\nleast 1.5 kpc perpendicular to the disk. In the outflow, CO gas is distributed\napproximately as a cylindrically symmetrical envelope surrounding the warm and\nhot ionized gas traced by H$\\alpha$ and soft X-rays. The velocity, mass outflow\nrate, and kinetic energy of the molecular outflow are\n$v_\\mathrm{w}\\sim100~\\mathrm{km~s^{-1}}$,\n$\\dot{M}_\\mathrm{w}\\sim7~M_\\odot~\\mathrm{yr}^{-1}$, and\n$E_\\mathrm{w}\\sim7\\times10^{54}~\\mathrm{erg}$, respectively.\n$\\dot{M}_\\mathrm{w}$ is comparable to the star formation rate\n($\\dot{M}_\\mathrm{w}/\\mathrm{SFR}\\sim2$) and $E_\\mathrm{w}$ is $\\sim1\\%$ of the\ntotal energy released by stellar feedback in the past\n$1\\times10^7~\\mathrm{yr}$, which is the dynamical timescale of the outflow. The\nresults indicate that the wind is starburst driven.", "positive": "Transformations between WISE and 2MASS, SDSS, BVI photometric systems:\n II. Transformation equations for red clump stars: We present colour transformations for the conversion of the Wide-Field Survey\nExplorer (WISE) W1, W2, and W3 magnitudes to the Johnson-Cousins (BVIc), Sloan\nDigital Sky Survey (gri), and Two Micron All Sky Survey JHKs photometric\nsystems, for red clump (RC) stars. RC stars were selected from the Third Radial\nVelocity Experiment (RAVE) Data Release (DR3). The apparent magnitudes were\ncollected by matching the coordinates of this sample with different photometric\ncatalogues. The final sample (355 RC stars) used to obtain metallicity\ndependent-and free of metallicity- transformations between WISE and\nJohnson-Cousins, SDSS, 2MASS photometric systems. These transformations\ncombined with known absolute magnitudes at shorter wavelengths can be used in\nspace density determinations for the Galactic (thin and thick) discs at\ndistances larger than the ones evaluated with JHKs photometry alone, hence\nproviding a powerful tool in the analysis of Galactic structure." }, { "anchor": "COSMOS2015 photometric redshifts probe the impact of filaments on galaxy\n properties: The variations of galaxy stellar masses and colour-types with the distance to\nprojected cosmic filaments are quantified using the precise photometric\nredshifts of the COSMOS2015 catalogue extracted from COSMOS field (2\ndeg$^{2}$). Realistic mock catalogues are also extracted from the lightcone of\nthe cosmological hydrodynamical simulation Horizon-AGN. They show that the\nphotometric redshift accuracy of the observed catalogue ($\\sigma_z<0.015$ at\n$M_*>10^{10}{\\rm M}_{\\odot}$ and $z<0.9$) is sufficient to provide 2D filaments\nthat closely match their projected 3D counterparts. Transverse stellar mass\ngradients are measured in projected slices of thickness 75 Mpc between $0.5< z\n<0.9$, showing that the most massive galaxies are statistically closer to their\nneighbouring filament. At fixed stellar mass, passive galaxies are also found\ncloser to their filament while active star-forming galaxies statistically lie\nfurther away. The contributions of nodes and local density are removed from\nthese gradients to highlight the specific role played by the geometry of the\nfilaments. We find that the measured signal does persist after this removal,\nclearly demonstrating that proximity to a filament is not equivalent to\nproximity to an over-density. These findings are in agreement with gradients\nmeasured both in 2D or 3D in the Horizon-AGN simulation and those observed in\nthe spectroscopic VIPERS survey (which rely on the identification of 3D\nfilaments). They are consistent with a picture in which the influence of the\ngeometry of the large-scale environment drives anisotropic tides which impact\nthe assembly history of galaxies, and hence their observed properties.", "positive": "Spatially resolved stellar population parameters in the BCGs of two\n fossil groups: We report the results of Gemini/GMOS long-slit spectroscopic observations\nalong the major and minor axes of the central galaxies in two fossil groups,\nSDSS J073422.21+265133.9 and SDSS J075828.11+374711.8 (the NGC 2484 group).\nSpatially resolved kinematics and stellar population parameters (ages,\nmetallicities and $\\alpha$-element abundance ratios) derived using ~20 Lick\nindices are presented. Despite remarkable similarities in their morphologies,\nphotometric properties (luminosity and colour) and kinematics, the two galaxies\nexhibit significantly different stellar population parameters.\n SDSS J073422.21+265133.9 exhibits a strong metallicity gradient\n(Delta[Z/H]/Delta R ~ -0.4) all the way into the centre of the galaxy. It also\nexhibits an age profile that suggest a relatively recent, centrally\nconcentrated burst of star formation superimposed on an older, more spatially\nextended population. NGC 2484, a well known X-ray AGN, exhibits a flat\ncore-like structure in its metallicity gradient, but no detectable age\ngradient. The alpha-element abundance ratio ([E/Fe]) profiles of the two\ngalaxies are also significantly different. SDSS J073422.21+265133.9 exhibits a\nslightly positive gradient (Delta [E/H]/Delta R ~ 0.1), perhaps again\nsuggesting a more recent central burst of star formation, while NGC 2484 shows\na negative gradient (Delta [E/H]/Delta R ~-0.1), indicating that star formation\nmay have happened \"inside out\".\n Our analysis of these two galaxies of similar mass, morphology and kinematics\ntherefore suggests two different mechanisms to have been in action during their\nformation. Consequently, we conclude that the central galaxies of fossil groups\ncan not be considered a homogeneous group with regard to their formation\nprocesses or star formation histories." }, { "anchor": "C II radiative cooling of the Galactic diffuse interstellar medium:\n Insight about the star formation in Damped Lyman-alpha systems: The far-infrared [C II] 158 micrometer fine structure transition is\nconsidered to be a dominant coolant in the interstellar medium. For this\nreason, under the assumption of a thermal steady state, it may be used to infer\nthe heating rate and, in turn, the star formation rate in local, as well as in\nhigh redshift systems. In this work, radio and ultraviolet observations of the\nGalactic interstellar medium are used to understand whether C II is indeed a\ngood tracer of the star formation rate. For a sample of high Galactic latitude\nsightlines, direct measurements of the temperature indicate the presence of C\nII in both the cold and the warm phases of the diffuse interstellar gas. The\ncold gas fraction (~ 10 - 50% of the total neutral gas column density) is not\nnegligible even at high Galactic latitude. It is shown that, to correctly\nestimate the star formation rate, C II cooling in both the phases should hence\nbe considered. The simple assumption, that the [C II] line originates only from\neither the cold or the warm phase, significantly underpredicts or overpredicts\nthe star formation rate, respectively. These results are particularly important\nin the context of the Damped Lyman-alpha systems for which a similar method is\noften used to estimate the star formation rate. The derived star formation\nrates in such cases may not be reliable if the temperature of the gas under\nconsideration is not constrained independently.", "positive": "Effects of Primordial Mass Segregation on the Dynamical Evolution of\n Star Clusters: In this paper we use N-body simulations to study the effects of primordial\nmass segregation on the early and long-term evolution of star clusters. Our\nsimulations show that in segregated clusters early mass loss due to stellar\nevolution triggers a stronger expansion than for unsegregated clusters. Tidally\nlimited, strongly segregated clusters may dissolve rapidly as a consequence of\nthis early expansion, while segregated clusters initially underfilling their\nRoche lobe can survive the early expansion and have a lifetime similar to that\nof unsegregated clusters. Long-lived initially segregated clusters tend to have\nlooser structure and reach core collapse later in their evolution than\ninitially unsegregated clusters. We have also compared the effects of dynamical\nevolution on the global stellar mass function (MF) of low-mass main sequence\nstars. In all cases the MF flattens as the cluster loses stars. The amount of\nMF flattening induced by a given amount of mass loss in a rapidly dissolving\ninitially segregated cluster is less than for an unsegregated cluster. The\nevolution of the MF of a long-lived segregated cluster, on the other hand, is\nvery similar to that of an initially unsegregated cluster." }, { "anchor": "Magnetic Ribbons: A Minimum Hypothesis Model for Filaments: We develop a magnetic ribbon model for molecular cloud filaments. These\nresult from turbulent compression in a molecular cloud in which the background\nmagnetic field sets a preferred direction. We use our model to calculate a\nsynthetic observed relation between apparent width in projection versus\nobserved column density. The relationship is relatively flat, in rough\nagreement with the observations, and unlike the simple expectation based on a\nJeans length argument.", "positive": "Interstellar dust modelling: Interfacing laboratory, theoretical and\n observational studies (The THEMIS model): The construction of viable and physically-realistic interstellar dust models\nis only possible if the constraints imposed by laboratory data on interstellar\ndust analogue materials are respected and used within a meaningful theoretical\nframework. These physical dust models can then be directly compared to\nobservations without the need for any tuning to fit the observations. Such\nmodels will generally fail to achieve the excellent fits to observations that\nempirical models are able to achieve. However, the physically-realistic\napproach will necessarily lead to a deeper insight and a fuller understanding\nof the nature and evolution of interstellar dust. The THEMIS modelling\napproach, based on (hydrogenated) amorphous carbons and amorphous silicates\nwith metallic Fe and/or FeS nano-inclusions appears to be a promising move in\nthis direction." }, { "anchor": "Initial Mass Function Variations Cannot Explain the Ionizing Spectrum of\n Low Metallicity Starbursts: Observations of both galaxies in the distant Universe and local starbursts\nare showing increasing evidence for very hard ionizing spectra that stellar\npopulation synthesis models struggle to reproduce. Here we explore the effects\nof the assumed stellar initial mass function (IMF) on the ionizing photon\noutput of young populations at wavelengths below key ionization energy\nthresholds. We use a custom set of binary population and spectral synthesis\n(BPASS) models to explore the effects of IMF assumptions as a function of\nmetallicity, IMF slope, upper mass limit, IMF power law break mass and\nsampling. We find that while the flux capable of ionizing hydrogen is only\nweakly dependent on IMF parameters, the photon flux responsible for the He II\nand O VI lines is far more sensitive to assumptions. In our current models this\nflux arises primarily from helium and Wolf-Rayet stars which have partially or\nfully lost their hydrogen envelopes. The timescales for formation and evolution\nof both Wolf Rayet stars and helium dwarfs, and hence inferred population age,\nare affected by choice of model IMF. Even the most extreme IMFs cannot\nreproduce the He II ionizing flux observed in some high redshift galaxies,\nsuggesting a source other than stellar photospheres. We caution that detailed\ninterpretation of features in an individual galaxy spectrum is inevitably going\nto be subject to uncertainties in the IMF of its contributing starbursts. We\nremind the community that the initial mass function is fundamentally a\nstatistical construct, and that stellar population synthesis models are most\neffective when considering entire galaxy populations rather than individual\nobjects.", "positive": "Measuring the gas reservoirs in $10^{8}<$ M$_\\star<10^{11}$ M$_\\odot$\n galaxies at $1\\leq z\\leq3$: Understanding the gas content in galaxies, its consumption and replenishment,\nremains pivotal in our comprehension of the evolution of the Universe. Numerous\nstudies have addressed this, utilizing various observational tools and\nanalytical methods. These include examining low-transition $^{12}$CO millimeter\nrotational lines and exploring the far-infrared and the (sub-)millimeter\nemission of galaxies. With the capabilities of present-day facilities, much of\nthis research has been centered on relatively bright galaxies. We aim at\nexploring the gas reservoirs of a more general type of galaxy population at\n$1.0\\leq z\\leq 3.0$. We stack ALMA 1.1 mm data to measure the gas content of a\nmass-complete sample down to $\\sim10^{8.6}$ M$_\\odot$ at $z=1$ ($\\sim10^{9.2}$\nM$_\\odot$ at $z=3$), extracted from the HST/CANDELS sample in GOODS-S. The\nsample is composed of 5,530 on average blue ($\\sim0.12$ mag,\n$\\sim0.81$ mag), star-forming main sequence objects\n($\\Delta$MS$\\sim-0.03$). We report measurements at $10^{10-11}$ M$_\\odot$ and\nupper limits for the gas fractions at $10^{8-10}$ M$_\\odot$. At $10^{10-11}$\nM$_\\odot$, our f$_{\\mathrm{gas}}$, ranging from 0.32 to 0.48, agree well with\nother studies based on mass-complete samples down to $10^{10}$ M$_\\odot$, and\nare lower than expected according to other works more biased to individual\ndetections. At $10^{9-10}$ M$_\\odot$, we obtain 3$\\sigma$ upper limits for\nf$_{\\mathrm{gas}}$ ranging from 0.69 to 0.77. These upper limits are on the\nlevel of the extrapolations of scaling relations based on mass-complete samples\ndown to $10^{10}$ M$_\\odot$. As such, it suggests that the gas content of\nlow-mass galaxies is at most what is extrapolated from literature scaling\nrelations. The comparison of our results with previous works reflects how the\ninclusion of bluer, less obscured, and more MS-like objects progressively\npushes the gas level to lower values." }, { "anchor": "xCOLDGASS and xGASS: Radial metallicity gradients and global properties\n on the star-forming main sequence: Context. The xGASS and xCOLD GASS surveys have measured the atomic (HI) and\nmolecular gas (H2) content of a large and representative sample of nearby\ngalaxies (redshift range of 0.01 $\\lt$ z $\\lt$ 0.05). Aims. We present optical\nlongslit spectra for a subset of the xGASS and xCOLD GASS galaxies to\ninvestigate the correlation between radial metallicity profiles and cold gas\ncontent. In addition to data from Moran et al. (2012), this paper presents new\noptical spectra for 27 galaxies in the stellar mass range of 9.0 $\\leq$ log\nMstar/Msun $\\leq$ 10.0. Methods. The longslit spectra were taken along the\nmajor axis of the galaxies, allowing us to obtain radial profiles of the\ngas-phase oxygen abundance (12 + log(O/H)). The slope of a linear fit to these\nradial profiles is defined as the metallicity gradient. We investigated\ncorrelations between these gradients and global galaxy properties, such as star\nformation activity and gas content. In addition, we examined the correlation of\nlocal metallicity measurements and the global HI mass fraction. Results. We\nobtained two main results: (i) the local metallicity is correlated with the\nglobal HI mass fraction, which is in good agreement with previous results. A\nsimple toy model suggests that this correlation points towards a 'local gas\nregulator model'; (ii) the primary driver of metallicity gradients appears to\nbe stellar mass surface density (as a proxy for morphology). Conclusions. This\nwork comprises one of the few systematic observational studies of the influence\nof the cold gas on the chemical evolution of star-forming galaxies, as\nconsidered via metallicity gradients and local measurements of the gas-phase\noxygen abundance. Our results suggest that local density and local HI mass\nfraction are drivers of chemical evolution and the gas-phase metallicity.", "positive": "Dusty Stellar Birth and Death in the Metal-Poor Galaxy NGC 6822: The nearby ($\\sim$500 kpc) metal-poor ([Fe/H] $\\approx$ -1.2; $Z$ $\\approx$\n30% $Z_{\\odot}$) star-forming galaxy NGC 6822 has a metallicity similar to\nsystems at the epoch of peak star formation. Through identification and study\nof dusty and dust-producing stars, it is therefore a useful laboratory to shed\nlight on the dust life cycle in the early Universe. We present a catalog of\nsources combining near- and mid-IR photometry from the United Kingdom Infrared\nTelescope (UKIRT; $J$, $H$, and $K$) and the $Spitzer$ $Space$ $Telescope$\n(IRAC 3.6, 4.5, 5.8, and 8.0 $\\mu$m and MIPS 24 $\\mu$m). This catalog is\nemployed to identify dusty and evolved stars in NGC 6822 utilizing three\ncolor-magnitude diagrams (CMDs). With diagnostic CMDs covering a wavelength\nrange spanning the near- and mid-IR, we develop color cuts using kernel density\nestimate (KDE) techniques to identify dust-producing evolved stars, including\nred supergiant (RSG) and thermally-pulsing asymptotic giant branch (TP-AGB)\nstar candidates. In total, we report 1,292 RSG candidates, 1,050 oxygen-rich\nAGB star candidates, and 560 carbon-rich AGB star candidates with high\nconfidence in NGC 6822. Our analysis of the AGB stars suggests a robust\npopulation inhabiting the central stellar bar of the galaxy, with a measured\nglobal stellar metallicity of [Fe/H] = -1.286 $\\pm$ 0.095, consistent with\nprevious studies. In addition, we identify 277 young stellar object (YSO)\ncandidates. The detection of a large number of YSO candidates within a\ncentrally-located, compact cluster reveals the existence of an embedded,\nhigh-mass star-formation region that has eluded previous detailed study.\nSpitzer I appears to be younger and more active than the other prominent\nstar-forming regions in the galaxy." }, { "anchor": "Large-scale magnetic field in the Monoceros OB-1 East molecular cloud: We study the large-scale magnetic field structure and its interplay with the\ngas dynamics in the Monoceros OB1 East molecular cloud. We combine observations\nof dust polarised emission from the Planck telescope and CO molecular line\nemission observations from the Taeduk Radio Astronomy Observatory 14-metre\ntelescope. We calculate the strength of the plane-of-the-sky magnetic field\nusing a modified Chandrasekhar-Fermi method and estimate mass over flux ratios\nin different regions of the cloud. We use the comparison of the velocity and\nintensity gradients of the molecular line observations with the polarimetric\nobservations to trace dynamically active regions. The molecular complex shows\nan ordered large-scale plane-of-the-sky magnetic field structure. In the\nNorthern part, it is mostly orientated along the filamentary structures while\nthe Southern part shows at least two regions with distinct magnetic field\norientations. We find that in the Northern filaments the magnetic field is\nunlikely to provide support against fragmentation at large scales. Our analysis\nreveals a shock region in the Northern part of the complex right in-between two\nfilamentary clouds which were previously suggested to be in collision.\nMoreover, the shock seems to extend farther towards the Western part of the\ncomplex. In the Southern part, we find that either the magnetic field guides\nthe accretion of interstellar matter towards the cloud or it was dragged by the\nmatter towards the densest regions. The large-scale magnetic field in Monoceros\nOB-1 East molecular clouds is tightly connected to the global structure of the\ncomplex and, in the Northern part, it seems to be dominated by gravity and\nturbulence, while in the Southern part it influences the structuring of matter.", "positive": "Feedback-regulated Super Massive Black Hole Seed Formation: The nature of the seeds of high-redshift supermassive black holes (SMBHs) is\na key question in cosmology. Direct collapse black holes (DCBH) that form in\npristine, atomic-line cooling halos, illuminated by a Lyman-Werner (LW) UV flux\nexceeding a critical threshold J_crit, represent an attractive possibility. We\ninvestigate when and where these conditions are met during cosmic evolution.\nFor the LW intensity, J_LW, we account for departures from the background value\nin close proximity to star forming galaxies. For the pristine halo fraction, we\naccount for both (i) supernova driven outflows, and (ii) the inherent pollution\nfrom progenitor halos. We estimate the abundance of DCBH formation sites,\nn_DCBH(z), and find that it increases with cosmic time from n_DCBH(z=20) ~\n1e-12 -1e-7 cMpc^-3 to n_DCBH(z=10) ~ 1e-10 - 1e-5 cMpc^-3. Our analysis shows\nthe possible importance of galactic winds, which can suppress the predicted\nn_DCBH by several orders of magnitude, and cause DCBH formation to\npreferentially occur around the UV-brightest (M_UV ~ -22 to -20) star forming\ngalaxies. Our analysis further highlights the dependence of these predictions\non (i) the escape fraction of LW photons, (ii) J_crit, and (iii) the galactic\noutflow prescription." }, { "anchor": "The systematic search for $z\\gtrsim5$ active galactic nuclei in the\n $Chandra$ Deep Field South: We investigate early black hole (BH) growth through the methodical search for\n$z\\gtrsim5$ AGN in the $Chandra$ Deep Field South. We base our search on the\n$Chandra$ 4-Ms data with flux limits of $9.1\\times\\ 10^{-18}$ (soft, 0.5 - 2\nkeV) and $5.5\\times\\ 10^{-17}\\ \\mathrm{erg}\\ \\mathrm{s}^{-1}\\ \\mathrm{cm}^{-2}$\n(hard, 2 - 8 keV). At $z\\sim5$ this corresponds to luminosities as low as\n$\\sim10^{42}$ ($\\sim10^{43}$) $\\mathrm{erg}\\ \\mathrm{s}^{-1}$ in the soft\n(hard) band and should allow us to detect Compton-thin AGN with\n$M_\\mathrm{BH}>10^7 M_{\\odot}$ and Eddington ratios > 0.1. Our field\n($0.03~\\mathrm{deg}^2$) contains over 600 $z\\sim5$ Lyman Break Galaxies. Based\non lower redshift relations we would expect $\\sim20$ of them to host AGN. After\ncombining the $Chandra$ data with GOODS/ACS, CANDELS/WFC3 and $Spitzer$/IRAC\ndata, the sample consists of 58 high-redshift candidates. We run a photometric\nredshift code, stack the GOODS/ACS data, apply colour criteria and the Lyman\nBreak Technique and use the X-ray Hardness Ratio. We combine our tests and\nusing additional data find that all sources are most likely at low redshift. We\nalso find five X-ray sources without a counterpart in the optical or infrared\nwhich might be spurious detections. We conclude that our field does not contain\nany convincing $z\\gtrsim5$ AGN. Explanations for this result include a low BH\noccupation fraction, a low AGN fraction, short, super-Eddington growth modes,\nBH growth through BH-BH mergers or in optically faint galaxies. By searching\nfor $z\\gtrsim5$ AGN we are setting the foundation for constraining early BH\ngrowth and seed formation scenarios.", "positive": "The halo mass function of late-type galaxies from HI kinematics: We present an empirical method to measure the halo mass function (HMF) of\ngalaxies. We determine the relation between the \\hi\\ line-width from\nsingle-dish observations and the dark matter halo mass ($M_{200}$) inferred\nfrom rotation curve fits in the SPARC database, then we apply this relation to\ngalaxies from the \\hi\\ Parkes All Sky Survey (HIPASS) to derive the HMF. This\nempirical HMF is well fit by a Schecther function, and matches that expected in\n$\\Lambda$CDM over the range $10^{10.5} < M_{200} <\n10^{12}\\;\\mathrm{M}_{\\odot}$. More massive halos must be poor in neutral gas to\nmaintain consistency with the power law predicted by $\\Lambda$CDM. We detect no\ndiscrepancy at low masses. The lowest halo mass probed by HIPASS, however, is\njust greater than the mass scale where the Local Group missing satellite\nproblem sets in. The integrated mass density associated with the dark matter\nhalos of \\hi-detected galaxies sums to $\\Omega_{\\rm m,gal} \\approx 0.03$ over\nthe probed mass range." }, { "anchor": "Mapping Dark Matter with Extragalactic Stellar Streams: the Case of\n Centaurus A: In the coming decade, thousands of stellar streams will be observed in the\nhalos of external galaxies. What fundamental discoveries will we make about\ndark matter from these streams? As a first attempt to look at these questions,\nwe model Magellan/Megacam imaging of the Centaurus A's (Cen A) disrupting dwarf\ncompanion Dwarf 3 (Dw3) and its associated stellar stream, to find out what can\nbe learned about the Cen A dark-matter halo. We develop a novel external galaxy\nstream-fitting technique and generate model stellar streams that reproduce the\nstream morphology visible in the imaging. We find that there are many viable\nstream models that fit the data well, with reasonable parameters, provided that\nCen A has a halo mass larger than M$_{200}$ $>4.70\\times 10^{12}$ M$_{\\odot}$.\nThere is a second stream in Cen A's halo that is also reproduced within the\ncontext of this same dynamical model. However, stream morphology in the imaging\nalone does not uniquely determine the mass or mass distribution for the Cen A\nhalo. In particular, the stream models with high likelihood show covariances\nbetween the inferred Cen A mass distribution, the inferred Dw3 progenitor mass,\nthe Dw3 velocity, and the Dw3 line-of-sight position. We show that these\ndegeneracies can be broken with radial-velocity measurements along the stream,\nand that a single radial velocity measurement puts a substantial lower limit on\nthe halo mass. These results suggest that targeted radial-velocity measurements\nwill be critical if we want to learn about dark matter from extragalactic\nstellar streams.", "positive": "The Nuclear Infrared Emission of Low-Luminosity AGN: We have obtained high-resolution mid-infrared (MIR) imaging, nuclear spectral\nenergy distributions (SEDs) and archival Spitzer spectra for 22 low-luminosity\nactive galactic nuclei (LLAGN; L_bol < 5 x 10^42 erg/s). Infrared (IR)\nobservations may advance our understanding of the accretion flows in LLAGN, the\nfate of the obscuring torus at low accretion rates, and, perhaps, the star\nformation histories of these objects. However, while comprehensively studied in\nhigher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGN have\nnot yet been well-determined. In these proceedings we summarise the results for\nthe LLAGN at the relatively high-luminosity, high-Eddington ratio end of the\nsample. Strong, compact nuclear sources are visible in the MIR images of these\nobjects, with luminosities consistent with or slightly in execss of that\npredicted by the standard MIR/X-ray relation. Their broadband nuclear SEDs are\ndiverse; some resemble typical Seyfert nuclei, while others possess less of a\nwell-defined MIR ``dust bump''. Strong silicate emission is present in many of\nthese objects. We speculate that this, together with high ratios of silicate\nstrength to hydrogen column density, could suggest optically thin dust and low\ndust-to-gas ratios, in accordance with model predictions that LLAGN do not host\na Seyfert-like obscuring torus." }, { "anchor": "Detection of highly ionized CIV gas within the Local Cavity: We present high resolution (R = 114,000) ultraviolet measurements of the\ninterstellar absorption line profiles of the CIV (1550 A) high ionization\ndoublet recorded towards the nearby B2Ve star HD 158427 (d~74pc). These data,\nwhich were recorded with the recently re-furbished STIS instrument on the HST,\nrepresent the most convincing detection yet of highly ionized CIV absorption\nthat can be associated with interstellar gas located within the boundary of the\nLocal Cavity. Two highly ionized gas clouds at V1 = -24.3 km/s and V2 = -41.3\nkm/s are revealed in both CIV absorption lines, with the V1 component almost\ncertainly being due to absorption by the Local Interstellar Cloud (d<5pc).\nAlthough the observed column densities for both cloud components can be\nexplained by the predictions of current theoretical models of the local\ninterstellar medium, the narrow doppler width of the V2 line-profile (b = 6.8\nkm/s) indicates an unusually low gas temperature of less than 34,000K for this\nhighly ionized component. It is conjectured that the V2 cloud may be due to an\noutflow of highly ionized and hot gas from the nearby Loop I superbubble. These\nnew data also indicate that absorption due to highly ionized gas in the Local\nCavity can be best described as being 'patchy' in nature.", "positive": "Orbital Torus Imaging: Using Element Abundances to Map Orbits and Mass\n in the Milky Way: Many approaches to galaxy dynamics assume that the gravitational potential is\nsimple and the distribution function is time-invariant. Under these assumptions\nthere are traditional tools for inferring potential parameters given\nobservations of stellar kinematics (e.g., Jeans models). However, spectroscopic\nsurveys measure many stellar properties beyond kinematics. Here we present a\nnew approach for dynamical inference, Orbital Torus Imaging, which makes use of\nkinematic measurements and element abundances (or other invariant labels). We\nexploit the fact that, in steady state, stellar labels vary systematically with\norbit characteristics (actions), yet must be invariant with respect to orbital\nphases (conjugate angles). The orbital foliation of phase space must therefore\ncoincide with surfaces along which all moments of all stellar label\ndistributions are constant. Both classical-statistics and Bayesian methods can\nbe built on this; these methods will be more robust and require fewer\nassumptions than traditional tools because they require no knowledge of the\n(spatial) survey selection function and they do not involve second moments of\nvelocity distributions. We perform a classical-statistics demonstration with\nred giant branch stars from the APOGEE surveys: We model the vertical orbit\nstructure in the Milky Way disk to constrain the local disk mass, scale height,\nand the disk--halo mass ratio (at fixed local circular velocity). We find that\nthe disk mass can be constrained (na\\\"ively) at the few-percent level with\nOrbital Torus Imaging using only eight element-abundance ratios, demonstrating\nthe promise of combining stellar labels with dynamical invariants." }, { "anchor": "H\u03b1 Dots: Direct-Method Metal Abundances of Low-Luminosity\n Star-Forming Systems: Utilizing low-luminosity star-forming systems discovered in the H$\\alpha$\nDots survey, we present spectroscopic observations undertaken using the KPNO 4m\ntelescope for twenty-six sources. With determinations of robust,\n\"direct\"-method metal abundances, we examine the properties of these dwarf\nsystems, exploring their utility in characterizing starburst galaxies at low\nluminosities and stellar masses. We find that the H$\\alpha$ Dots survey\nprovides an effective new avenue for identifying star-forming galaxies in these\nregimes. In addition, we examine abundance characteristics and metallicity\nscaling relations with these sources, highlighting a flattening of both the\nluminosity-metallicity ($L$-$Z$) and stellar mass-metallicity ($M_{*}$-$Z$)\nrelation slopes in these regimes as compared with those utilizing samples\ncovering wider respective dynamic ranges. These local, accessible analogues to\nthe kinds of star-forming dwarfs common at high redshift will help shed light\non the building blocks which assembled into the massive galaxies common today.", "positive": "Interstellar absorption and dust scattering: The study of the interstellar medium (ISM) in the X-rays has entered a golden\nage with the advent of the X-ray observatories XMM-Newton and Chandra.\nHigh-energy resolution allowed to study dust spectroscopic features with\nunprecedented detail. At the same time, the X-ray imaging capabilities offered\na new perspective of dust scattering halos. Both spectroscopy and imaging rely\non a simple geometry, where a distant X-ray source, usually a bright X-ray\nbinary system, lies behind a multi-layered ISM. X-ray binaries can be found in\ndifferent regions in the Galaxy, providing the unique chance to study the ISM\nin distinct environments. In the following we will describe how X-rays can be\nused as a tool to study gas and dust along the line of sight, revealing\nelemental abundances and depletion. The study of interstellar dust\nspectroscopic and imaging features can be used to extract the chemical and\nphysical properties of the intervening dust, as well as its distribution along\nthe line of sight." }, { "anchor": "Using KCWI to Explore the Chemical Inhomogeneities and Evolution of\n J1044+0353: J1044+0353 is considered a local analog of the young galaxies that ionized\nthe intergalactic medium at high-redshift due to its low mass, low metallicity,\nhigh specific star formation rate, and strong high-ionization emission lines.\nWe use integral field spectroscopy to trace the propagation of the starburst\nacross this small galaxy using Balmer emission- and absorption-line equivalent\nwidths and find a post-starburst population (~ 15 - 20 Myr) roughly one kpc\neast of the much younger, compact starburst (~ 3 - 4 Myr). Using the direct\nelectron temperature method to map the O/H abundance ratio, we find similar\nmetallicity (1 to 3 sigma) between the starburst and post-starburst regions but\nwith a significant dispersion of about 0.3 dex within the latter. We also map\nthe Doppler shift and width of the strong emission lines. Over scales several\ntimes the size of the galaxy, we discover a velocity gradient parallel to the\ngalaxy's minor axis. The steepest gradients (~ 30 $\\mathrm{km \\ s^{-1} \\\nkpc^{-1}}$) appear to emanate from the oldest stellar association. We identify\nthe velocity gradient as an outflow viewed edge-on based on the increased line\nwidth and skew in a biconical region. We discuss how this outflow and the gas\ninflow necessary to trigger the starburst affect the chemical evolution of\nJ1044+0353. We conclude that the stellar associations driving the galactic\noutflow are spatially offset from the youngest association, and a chemical\nevolution model with a metal-enriched wind requires a more realistic inflow\nrate than a homogeneous chemical evolution model.", "positive": "The Contribution Of Outer HI Disks To The Merging Binary Black Hole\n Population: We investigate the contribution of outer HI disks to the observable\npopulation of merging black hole binaries. Like dwarf galaxies, the outer HI\ndisks of spirals have low star formation rates and lower metallicities than the\ninner disks of spirals. Since low-metallicity star formation can produce more\ndetectable compact binaries than typical star formation, the environments in\nthe outskirts of spiral galaxies may be conducive to producing a rich\npopulation of massive binary black holes. We consider here both detailed\ncontrolled simulations of spirals and cosmological simulations, as well as the\ncurrent range of observed values for metallicity and star formation in outer\ndisks. We find that outer HI disks contribute at least as much as dwarf\ngalaxies do to the observed LIGO/Virgo detection rates. Identifying the host\ngalaxies of merging massive black holes should provide constraints on\ncosmological parameters and insights into the formation channels of binary\nmergers." }, { "anchor": "A Global Semi-Analytic Model of the First Stars and Galaxies Including\n Dark Matter Halo Merger Histories: We present a new self-consistent semi-analytic model of the first stars and\ngalaxies to explore the high-redshift ($z{>}15$) Population III (PopIII) and\nmetal-enriched star formation histories. Our model includes the detailed merger\nhistory of dark matter halos generated with Monte Carlo merger trees. We\ncalibrate the minimum halo mass for PopIII star formation from recent\nhydrodynamical cosmological simulations that simultaneously include the\nbaryon-dark matter streaming velocity, Lyman-Werner (LW) feedback, and\nmolecular hydrogen self-shielding. We find an overall increase in the resulting\nstar formation rate density (SFRD) compared to calibrations based on previous\nsimulations (e.g., the PopIII SFRD is over an order of magnitude higher at\n$z=35-15$). We evaluate the effect of the halo-to-halo scatter in this critical\nmass and find that it increases the PopIII stellar mass density by a factor of\n${\\sim}1.5$ at $z{>}15$. Additionally, we assess the impact of various\nsemi-analytic/analytic prescriptions for halo assembly and star formation\npreviously adopted in the literature. For example, we find that models assuming\nsmooth halo growth computed via abundance matching predict SFRDs similar to the\nmerger tree model for our fiducial model parameters, but that they may\nunderestimate the PopIII SFRD in cases of strong LW feedback. Finally, we\nsimulate sub-volumes of the Universe with our model both to quantify the\nreduction in total star formation in numerical simulations due to a lack of\ndensity fluctuations on spatial scales larger than the simulation box, and to\ndetermine spatial fluctuations in SFRD due to the diversity in halo abundances\nand merger histories.", "positive": "Formation of dense structures induced by filament collisions.\n Correlation of density, kinematics and magnetic field in the Pipe nebula: Context. The Pipe nebula is a molecular cloud that lacks star formation\nfeedback and has a relatively simple morphology and velocity structure. This\nmakes it an ideal target to test cloud evolution through collisions. Aims. We\naim at drawing a comprehensive picture of this relatively simple cloud to\nbetter understand the formation and evolution of molecular clouds on large\nscales. Methods. We use archival data to compare the optical polarization\nproperties, the visual extinction, and the 13CO velocities and linewidths of\nthe entire cloud in order to identify trends among the observables. Results.\nThe Pipe nebula can be roughly divided in two filaments with different\norientations and gas velocity ranges: E-W at 2-4 km s-1 and N-S at 6-7 km s-1.\nThe two filaments overlap at the bowl, where the gas shows a velocity gradient\nspanning from 2 to 7 km s-1. Compared to the rest of the Pipe nebula, the bowl\ngas appears to be denser and exhibits larger linewidths. In addition, the\npolarization data at the bowl shows lower angular dispersion and higher\npolarization degree. Cores in the bowl tend to cluster in space and tend to\nfollow the 13CO velocity gradient. In the stem, cores tend to cluster in\nregions with properties similar to those of the bowl. Conclusions. The velocity\npattern points to a collision between the filaments in the bowl region. The\nmagnetic field seems to be compressed and strengthened in the shocked region.\nThe proportional increase of density and magnetic field strength by a factor\nsimilar to the Alfv\\'enic Mach number suggests a continuous shock at low\nAlfv\\'enic Mach number under flux-freezing. Shocked regions seem to enhance the\nformation and clustering of dense cores." }, { "anchor": "The CGM and IGM at z$\\sim$5: metal budget and physical connection: We present further results of a survey for absorption line systems in the\nspectra of four high redshift quasars (5.79 $\\le$ z$_{\\textrm{em}}$ $\\le$ 6.13)\nobtained with the ESO Very Large Telescope X-Shooter. We identify 36\n$\\textrm{CIV}$ and 7 $\\textrm{SiIV}$ systems with a $\\ge$ 5$\\sigma$\nsignificance. The highest redshift $\\textrm{CIV}$ and $\\textrm{SiIV}$ absorbers\nidentified in this work are at z = 5.80738 $\\pm$ 0.00017 and z = 5.77495 $\\pm$\n0.00038, respectively. We compute the comoving mass density of $\\textrm{SiIV}$\n($\\Omega_{\\textrm{SiIV}}$) and find that it evolves from\n$\\Omega_{\\textrm{SiIV}}$ = 4.3$^{+2.1}_{-2.1}$ $\\times$10$^{-9}$ at = 5.05\nto $\\Omega_{\\textrm{SiIV}}$ = 1.4$^{+0.6}_{-0.4}$ $\\times$10$^{-9}$ at =\n5.66. We also measure $\\Omega_{\\textrm{CIV}}$ = 1.6$^{+0.4}_{-0.1}$\n$\\times$10$^{-8}$ at = 4.77 and $\\Omega_{\\textrm{CIV}}$ =\n3.4$^{+1.6}_{-1.1}$ $\\times$10$^{-9}$ at = 5.66. We classify our\n$\\textrm{CIV}$ absorber population by the presence of associated $\\textit{low}$\nand/or $\\textit{high ionisation}$ systems and compute their velocity width\n($\\Delta$v$_{90}$). We find that all $\\textrm{CIV}$ systems with\n$\\Delta$v$_{90}$ > 200 kms$^{-1}$ have associated $\\textit{low ionisation}$\nsystems. We investigate two such systems, separated by 550 physical kpc along a\nline of sight, and find it likely that they are both tracing a multi-phase\nmedium where hot and cold gas is mixing at the interface between the CGM and\nIGM. We further discuss the \\textrm{MgII} systems presented in a previous work\nand we identify 5 $\\textrm{SiII}$, 10 $\\textrm{AlII}$, 12 $\\textrm{FeII}$, 1\n$\\textrm{CII}$, 7 $\\textrm{MgI}$ and 1 $\\textrm{CaII}$ associated transitions.\nWe compute the respective comoving mass densities in the redshift range 2 to 6,\nas allowed by the wavelength coverage.", "positive": "Star-disc interaction in galactic nuclei: formation of a central stellar\n disc: We perform high resolution direct $N$-body simulations to study the effect of\nan accretion disc on stellar dynamics in an active galactic nucleus (AGN). We\nshow that the interaction of the nuclear stellar cluster (NSC) with the gaseous\ndisc (AD) leads to formation of a stellar disc in the central part of the NSC.\nThe accretion of stars from the stellar disc onto the super-massive black hole\nis balanced by the capture of stars from the NSC into the stellar disc,\nyielding a stationary density profile. We derive the migration time through the\nAD to be 3\\% of the half-mass relaxation time of the NSC. The mass and size of\nthe stellar disc are 0.7\\% of the mass and 5\\% of the influence radius of the\nsuper-massive black hole. An AD lifetime shorter than the migration time would\nresult in a less massive nuclear stellar disc. The detection of such a stellar\ndisc could point to past activity of the hosting galactic nucleus." }, { "anchor": "Self-Consistent Analysis of OH-Zeeman Observations: Too Much Noise about\n Noise: We had recently re-analyzed in a self-consistent way OH-Zeeman observations\nin four molecular-cloud envelopes and we had shown that, contrary to claims by\nCrutcher et al., there is no evidence that the mass-to-flux ratio decreases\nfrom the envelopes to the cores of these clouds. The key difference between our\ndata analysis and the earlier one by Crutcher et al. is the relaxation of the\noverly restrictive assumption made by Crutcher et al, that the magnetic field\nstrength is independent of position in each of the four envelopes. In a more\nrecent paper, Crutcher et al. (1) claim that our analysis is not\nself-consistent, in that it misses a cosine factor, and (2) present new\narguments to support their contention that the magnetic-field strength is\nindeed independent of position in each of the four envelopes. We show that the\nclaim of the missing cosine factor is false, that the new arguments contain\neven more serious problems than the Crutcher et al. original data analysis, and\nwe present new observational evidence, independent of the OH-Zeeman data, that\nsuggests significant variations in the magnetic-field strength in the four\ncloud envelopes.", "positive": "High-resolution Observations of Low-luminosity Gigahertz-Peaked Spectrum\n and Compact Steep Spectrum Sources: We present Very Long Baseline Interferometry observations of a faint and\nlow-luminosity ($L_{\\rm 1.4 GHz} < 10^{27}~\\mbox{W Hz}^{-1}$) Gigahertz-Peaked\nSpectrum (GPS) and Compact Steep Spectrum (CSS) sample. We select eight sources\nfrom deep radio observations that have radio spectra characteristic of a GPS or\nCSS source and an angular size of $\\theta \\lesssim 2$ arcsec, and detect six of\nthem with the Australian Long Baseline Array. We determine their linear sizes,\nand model their radio spectra using Synchrotron Self Absorption (SSA) and Free\nFree Absorption (FFA) models. We derive statistical model ages, based on a\nfitted scaling relation, and spectral ages, based on the radio spectrum, which\nare generally consistent with the hypothesis that GPS and CSS sources are young\nand evolving. We resolve the morphology of one CSS source with a radio\nluminosity of $10^{25}~\\mbox{W Hz}^{-1}$, and find what appear to be two\nhotspots spanning 1.7 kpc. We find that our sources follow the turnover-linear\nsize relation, and that both homogenous SSA and an inhomogeneous FFA model can\naccount for the spectra with observable turnovers. All but one of the FFA\nmodels do not require a spectral break to account for the radio spectrum, while\nall but one of the alternative SSA and power law models do require a spectral\nbreak to account for the radio spectrum. We conclude that our low-luminosity\nsample is similar to brighter samples in terms of their spectral shape,\nturnover frequencies, linear sizes, and ages, but cannot test for a difference\nin morphology." }, { "anchor": "Constraining the Milky Way Mass with Its Hot Gaseous Halo: We propose a novel method to constrain the Milky Way (MW) mass $M_{\\rm vir}$\nwith its corona temperature observations. For a given corona density profile,\none can derive its temperature distribution assuming a generalized equilibrium\nmodel with non-thermal pressure support. While the derived temperature profile\ndecreases substantially with radius, the X-ray-emission-weighted average\ntemperature, which depends most sensitively on $M_{\\rm vir}$, is quite uniform\ntoward different sight lines, consistent with X-ray observations. For an\nNavarro-Frenk-White (NFW) total matter distribution, the corona density profile\nshould be cored, and we constrain $M_{\\rm vir}=(1.19$ - $2.95) \\times 10^{12}\nM_{\\rm sun}$. For a total matter distribution contributed by an NFW dark matter\nprofile and central baryons, the corona density profile should be cuspy and\n$M_{\\rm vir,dm}=(1.34$ - $5.44) \\times 10^{12} M_{\\rm sun}$. Non-thermal\npressure support leads to even higher values of $M_{\\rm vir}$, while a lower MW\nmass may be possible if the corona is accelerating outward. This method is\nindependent of the total corona mass, its metallicity, and temperature at very\nlarge radii.", "positive": "Resolved spectral variations of the centimetre-wavelength continuum from\n the rho Oph W photo-dissociation-region: Cm-wavelength radio continuum emission in excess of free-free, synchrotron\nand Rayleigh-Jeans dust emission (excess microwave emission, EME), and often\ncalled `anomalous microwave emission', is bright in molecular cloud regions\nexposed to UV radiation, i.e. in photo-dissociation regions (PDRs). The EME\ncorrelates with IR dust emission on degree angular scales. Resolved\nobservations of well-studied PDRs are needed to compare the spectral variations\nof the cm-continuum with tracers of physical conditions and of the dust grain\npopulation. The EME is particularly bright in the regions of the rho Ophiuchi\nmolecular cloud (rho Oph) that surround the earliest type star in the complex,\nHD 147889, where the peak signal stems from the filament known as the rho Oph-W\nPDR. Here we report on ATCA observations of rho Oph-W that resolve the width of\nthe filament. We recover extended emission using a variant of non-parametric\nimage synthesis performed in the sky plane. The multi-frequency 17 GHz to 39\nGHz mosaics reveal spectral variations in the cm-wavelength continuum. At ~30\narcsec resolutions, the 17-20 GHz intensities follow tightly the mid-IR, Icm\npropto I(8 um), despite the breakdown of this correlation on larger scales.\nHowever, while the 33-39 GHz filament is parallel to IRAC 8 mum, it is offset\nby 15-20 arcsec towards the UV source. Such morphological differences in\nfrequency reflect spectral variations, which we quantify spectroscopically as a\nsharp and steepening high-frequency cutoff, interpreted in terms of the\nspinning dust emission mechanism as a minimum grain size a_cutoff ~ 6 +- 1A\nthat increases deeper into the PDR." }, { "anchor": "ALMA observations of dust polarization and molecular line emission from\n the Class 0 protostellar source Serpens SMM1: We present high angular resolution dust polarization and molecular line\nobservations carried out with the Atacama Large Millimeter/submillimeter Array\n(ALMA) toward the Class 0 protostar Serpens SMM1. By complementing these\nobservations with new polarization observations from the Submillimeter Array\n(SMA) and archival data from the Combined Array for Research in Millimeter-wave\nAstronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare\nthe magnetic field orientations at different spatial scales. We find major\nchanges in the magnetic field orientation between large (~0.1 pc) scales --\nwhere the magnetic field is oriented E-W, perpendicular to the major axis of\nthe dusty filament where SMM1 is embedded -- and the intermediate and small\nscales probed by CARMA (~1000 AU resolution), the SMA (~350 AU resolution), and\nALMA (~140 AU resolution). The ALMA maps reveal that the redshifted lobe of the\nbipolar outflow is shaping the magnetic field in SMM1 on the southeast side of\nthe source; however, on the northwestern side and elsewhere in the source, low\nvelocity shocks may be causing the observed chaotic magnetic field pattern.\nHigh-spatial-resolution continuum and spectral-line observations also reveal a\ntight (~130 AU) protobinary system in SMM1-b, the eastern component of which is\nlaunching an extremely high-velocity, one-sided jet visible in both CO(2-1) and\nSiO(5-4); however, that jet does not appear to be shaping the magnetic field.\nThese observations show that with the sensitivity and resolution of ALMA, we\ncan now begin to understand the role that feedback (e.g., from protostellar\noutflows) plays in shaping the magnetic field in very young, star-forming\nsources like SMM1.", "positive": "Deep ALMA redshift search of a z~12 GLASS-JWST galaxy candidate: The James Webb Space Telescope (JWST) has discovered a surprising abundance\nof bright galaxy candidates in the very early Universe ($< 500$ Myrs after the\nBig Bang), calling into question current galaxy formation models. Spectroscopy\nis needed to confirm the primeval nature of these candidates, as well as to\nunderstand how the first galaxies form stars and grow. Here we present deep\nspectroscopic and continuum ALMA observations towards GHZ2/GLASS-z12, one of\nthe brightest and most robust candidates at $z > 10$ identified in the\nGLASS-JWST Early Release Science Program. We detect a $5.8 \\sigma$ line, offset\n0.5\" from the JWST position of GHZ2/GLASS-z12 that, associating it with the\n[OIII] 88 micron transition, implies a spectroscopic redshift of $z = 12.117\n\\pm 0.001$. We verify the detection using extensive statistical tests. The\noxygen line luminosity places GHZ2/GLASS-z12 above the [OIII]-SFR relation for\nmetal-poor galaxies, implying an enhancement of [OIII] emission in this system\nwhile the JWST-observed emission is likely a lower-metallicity region. The lack\nof dust emission seen by these observations is consistent with the blue UV\nslope observed by JWST, which suggest little dust attenuation in galaxies at\nthis early epoch. Further observations will unambiguously confirm the redshift\nand shed light on the origins of the wide and offset line and physical\nproperties of this early galaxy. This work illustrates the synergy between JWST\nand ALMA and paves the way for future spectroscopic surveys of $z > 10$ galaxy\ncandidates." }, { "anchor": "Interferometry of class I methanol masers, statistics and the distance\n scale: The Australia Telescope Compact Array (ATCA) participated in a number of\nsurvey programs to search for and image common class I methanol masers (at 36\nand 44 GHz) with high angular resolution. In this paper, we discuss spatial and\nvelocity distributions revealed by these surveys. In particular, the number of\nmaser regions is found to fall off exponentially with the linear distance from\nthe associated young stellar object traced by the 6.7-GHz maser, and the scale\nof this distribution is 263+/-15 milliparsecs. Although this relationship still\nneeds to be understood in the context of the broader field, it can be utilised\nto estimate the distance using methanol masers only. This new technique has\nbeen analysed to understand its limitations and future potential. It turned\nout, it can be very successful to resolve the ambiguity in kinematic distances,\nbut, in the current form, is much less accurate (than the kinematic method) if\nused on its own.", "positive": "AGN and starburst in bright Seyfert galaxies: from IR photometry to IR\n spectroscopy: Infrared photometry and later infrared spectroscopy provided powerful\ndiagnostics to distinguish between the main emission mechanisms in galaxies:\nAGN and Starburst. After the pioneering work on infrared photometry with IRAS\nin the far-IR and the S.Pedro Martir and ESO ground-based work in the near-IR,\nISO photometry extended up to 200um the coverage of the galaxies energy\ndistributions. Then Spitzer collected accurate mid-infrared spectroscopy on\ndifferent samples of galaxies. We will review the work done on the 12um galaxy\nsample since the times of IRAS photometry to the new Spitzer spectroscopy. The\nmain results on the multifrequency data of 12um selected Seyfert galaxies are\npresented and discussed in the light of unification and evolution models. The\nspectroscopic work of Spitzer will soon be complemented at longer wavelengths\nby the Herschel spectrometers and in the future by SPICA at higher redshift." }, { "anchor": "The presence of interstellar scintillation in the 15 GHz interday\n variability of 1158 OVRO-monitored blazars: We have conducted the first systematic search for interday variability in a\nlarge sample of extragalactic radio sources at 15 GHz. From the sample of 1158\nradio-selected blazars monitored over a $\\sim$10 year span by the Owens Valley\nRadio Observatory 40-m telescope, we identified 20 sources exhibiting\nsignificant flux density variations on 4-day timescales. The sky distribution\nof the variable sources is strongly dependent on the line-of-sight Galactic\nH$\\alpha$ intensities from the Wisconsin H$\\alpha$ Mapper Survey, demonstrating\nthe contribution of interstellar scintillation (ISS) to their interday\nvariability. 21% of sources observed through sight-lines with H$\\alpha$\nintensities larger than 10 rayleighs exhibit significant ISS persistent over\nthe $\\sim$10 year period. The fraction of scintillators is potentially larger\nwhen considering less significant variables missed by our selection criteria,\ndue to ISS intermittency. This study demonstrates that ISS is still important\nat 15 GHz, particularly through strongly scattered sight-lines of the Galaxy.\nOf the 20 most significant variables, 11 are observed through the\nOrion-Eridanus superbubble, photoionized by hot stars of the Orion OB1\nassociation. The high-energy neutrino source TXS0506$+$056 is observed through\nthis region, so ISS must be considered in any interpretation of its short-term\nradio variability. J0616$-$1041 appears to exhibit large $\\sim$20% interday\nflux density variations, comparable in magnitude to that of the very rare class\nof extreme, intrahour scintillators that includes PKS0405$-$385, J1819$+$3845\nand PKS1257$-$326; this needs to be confirmed by higher cadence follow-up\nobservations.", "positive": "The role of massive halos in the Star Formation History of the Universe: The most striking feature of the Cosmic Star Formation History (CSFH) of the\nUniverse is a dramatic drop of the star formation (SF) activity, since z~1. In\nthis work we investigate if the very same process of assembly and growth of\nstructures is one of the major drivers of the observed decline. We study the\ncontribution to the CSFH of galaxies in halos of different masses. This is done\nby studying the total SFR-halo mass-redshift plane from redshift 0 to redshift\nz~1.6 in a sample of 57 groups and clusters by using the deepest available mid-\nand far-infrared surveys conducted with Spitzer MIPS and Herschel PACS and\nSPIRE. Our results show that low mass groups provide a 60-80% contribution to\nthe CSFH at z~1. Such contribution declines faster than the CSFH in the last 8\nbillion years to less than 10% at z<0.3, where the overall SF activity is\nsustained by lower mass halos. More massive systems provide only a marginal\ncontribution (<10%) at any epoch. A simplified abundance matching method shows\nthat the large contribution of low mass groups at z~1 is due to a large\nfraction (>50%) of very massive, highly star forming Main Sequence galaxies.\nBelow z~1 a quenching process must take place in massive halos to cause the\nobserved faster suppression of their SF activity. Such process must be a slow\none though, as most of the models implementing a rapid quenching of the SF\nactivity in accreting satellites significantly underpredicts the observed SF\nlevel in massive halos at any redshift. Starvation or the transition from cold\nto hot accretion would provide a quenching timescale of 1 Gyrs more consistent\nwith the observations. Our results suggest a scenario in which, due to the\nstructure formation process, more and more galaxies experience the group\nenvironment and, thus, the associated quenching process. This leads to the\nprogressive suppression of their SF activity shaping the CSFH below z~1." }, { "anchor": "Broad emission lines in optical spectra of hot dust-obscured galaxies\n can contribute significantly to JWST/NIRCam photometry: Selecting the first galaxies at z>7-10 from JWST surveys is complicated by\nz<6 contaminants with degenerate photometry. For example, strong optical\nnebular emission lines at z<6 may mimic JWST/NIRCam photometry of z>7-10 Lyman\nBreak Galaxies (LBGs). Dust-obscured 3-1.5$ and z>4. While there are some\nredshifts (z~3.75) where our stack is more degenerate with the photometry of\nz>10 LBGs between $\\lambda_{rest}\\sim0.3-0.8\\,\\mu$m, redder filter coverage\nbeyond $\\lambda_{obs}>3.5\\,\\mu$m and far-IR/sub-mm follow-up may be useful for\nbreaking the degeneracy and making a crucial separation between two fairly\nunconstrained populations, dust-obscured galaxies at z~3-6 and LBGs at z>10.", "positive": "Properties of an accretion disc with a power-law stress-pressure\n relationship: Recent numerical simulations of magnetized accretion discs show that the\nradial-azimuthal component of the stress tensor due to the magnetorotational\ninstability (MRI) is well represented by a power-law function of the gas\npressure rather than a linear relation which has been used in most of the\naccretion disc studies. The exponent of this power-law function which depends\non the net flux of the imposed magnetic field is reported in the range between\nzero and unity. However, the physical consequences of this power-law\nstress-pressure relation within the framework of the standard disc model have\nnot been explored so far. In this study, the structure of an accretion disc\nwith a power-law stress-pressure relation is studied using analytical solutions\nin the steady-state and time-dependent cases. The derived solutions are\napplicable to different accreting systems, and as an illustrative example, we\nexplore structure of protoplanetary discs using these solutions. We show that\nthe slopes of the radial surface density and temperature distributions become\nsteeper with decreasing the stress exponent. However, if the disc opacity is\ndominated by icy grains and value of the stress exponent is less than about\n$0.5$, the surface density and temperature profiles become so steep that make\nthem unreliable. We also obtain analytical solutions for the protoplanetary\ndiscs which are irradiated by the host star. Using these solutions, we find\nthat the effect of the irradiation becomes more significant with decreasing the\nstress exponent." }, { "anchor": "First detection of CS masers around a high-mass young stellar object,\n W51 e2e: We report the discovery of maser emission in the two lowest rotational\ntransitions of CS toward the high-mass protostar W51 e2e with ALMA and the\nJVLA. The masers from CS J=1-0 and J=2-1 are neither spatially nor spectrally\ncoincident (they are separated by ~150 AU and ~30 km/s), but both appear to\ncome from the base of the blueshifted outflow from this source. These CS masers\njoin a growing list of rarely-detected maser transitions that may trace a\nunique phase in the formation of high-mass protostars.", "positive": "Possible evolution of the circum-galactic medium around QSOs with QSO\n age and cosmic time revealed by Ly$\u03b1$ halos: We first present new Subaru narrow-band observations of the Ly$\\alpha$ halo\naround the quasi-stellar object (QSO) CFHQ J232908$-$030158 at $z=6.42$, which\nappears the most luminous and extended halo at $z>5$\n($L_{Ly\\alpha}=9.8\\times10^{43}$ erg s$^{-1}$ within $37$ pkpc diameter). Then,\ncombining these measurements with available data in the literature, we find two\ndifferent evolutions of QSOs' Ly$\\alpha$ halos. First is a possible short-term\nevolution with QSO age seen in four $z>6$ QSOs. We find the anti-correlation\nbetween the Ly$\\alpha$ halo scales with QSOs' IR luminosity, with J2329-0301's\nhalo being the brightest and largest. It indicates that ionizing photons escape\nmore easily out to circum-galactic regions when host galaxies are less dusty.\nWe also find a positive correlation between IR luminosity and black hole mass\n($M_\\text{BH}$). Given $M_\\text{BH}$ as an indicator of QSO age, we propose a\nhypothesis that a large Ly$\\alpha$ halo mainly exists around QSOs in the young\nphase of their activity due to a small amount of dust. The second is an\nevolution with cosmic time seen over $z\\sim2-5$. We find the increase of\nsurface brightness toward lower-redshift with a similar growth rate to that of\ndark matter halos (DHs) which evolve to $M_\\text{DH}=10^{12}-10^{13}$ M$_\\odot$\nat $z=2$. The extent of Ly$\\alpha$ halos is also found to increase at a rate\nscaling with the virial radius of growing DHs, $r_\\text{vir} \\propto\nM_\\text{DH}^{1/3}$($1+z$)$^{-1}$. These increases are consistent with a\nscenario that the CGM around QSOs evolves in mass and size keeping pace with\nhosting DHs." }, { "anchor": "Hyper-massive Black Holes have Faint Broad and Narrow Emission Lines: The EUV provides most of the ionization that creates the high equivalent\nwidth (EW) broad and narrow emission lines (BELs, NELs) of quasars. Spectra of\nHypermassive Schwarzschild black holes (HMBHs, $M_{BH} \\geq 10^{10} M_{\\odot}$)\nwith $\\alpha$-discs, decline rapidly in the EUV suggesting much lower EWs.\nModel spectra for black holes of mass $10^{6}-10^{12} M_{\\odot}$ and accretion\nrates $0.03 \\leq L_{bol}/L_{edd} \\leq 1.0$ were input to the CLOUDY\nphotoionization code. BELs become $\\sim$100 times weaker in EW from $M_{BH}\n\\sim 10^8 M_{\\odot}$ to $M_{BH} \\sim 10^{10} M_{\\odot}$. The high ionization\nBELs (O VI 1034 $\\overset{\\circ}{\\mathrm {A}}$, C IV 1549\n$\\overset{\\circ}{\\mathrm {A}}$, He II 1640 $\\overset{\\circ}{\\mathrm {A}}$)\ndecline in EW from ($M_{BH} \\geq 10^6 M_{\\odot}$, reproducing the Baldwin\neffect, but regain EW for $M_{BH} \\geq 10^{10} M_{\\odot}$). The low ionization\nlines (MgII 2798 $\\overset{\\circ}{\\mathrm {A}}$, H$\\beta$ 4861\n$\\overset{\\circ}{\\mathrm {A}}$ and H$\\alpha$ 6563 $\\overset{\\circ}{\\mathrm\n{A}}$) remain weak. Lines for maximally spinning HMBHs behave similarly. Line\nratio diagrams for the BELs show that high OVI/H$\\beta$ and low CIV/H$\\alpha$\nmay pick out HMBH, although OVI is often hard to observe. In NEL BPT diagrams\nHMBHs lie among star-forming regions, except for highly spinning, high\naccretion rate HMBHs. In summary, the BELs expected from HMBHs would be hard to\ndetect using the current optical facilities. From 100 to $10^{12} M_{\\odot}$,\nthe emission lines used to detect AGN only have high EW in the $10^6 - 10^9\nM_{\\odot}$ window, where most AGN are found. This selection effect may be\ndistorting reported distributions of $M_{BH}$.", "positive": "Investigating the structure of star-forming regions using INDICATE: The ability to make meaningful comparisons between theoretical and\nobservational data of star-forming regions is key to understanding the star\nformation process. In this paper we test the performance of INDICATE, a new\nmethod to quantify the clustering tendencies of individual stars in a region,\non synthetic star-forming regions with sub-structured, and smooth, centrally\nconcentrated distributions. INDICATE quantifies the amount of stellar\naffiliation of each individual star, and also determines whether this\naffiliation is above random expectation for the star-forming region in\nquestion. We show that INDICATE cannot be used to quantify the overall\nstructure of a region due to a degeneracy when applied to regions with\ndifferent geometries. We test the ability of INDICATE to detect differences in\nthe local stellar surface density and its ability to detect and quantify mass\nsegregation. We then compare it to other methods such as the mass segregation\nratio $\\Lambda_{\\rm{MSR}}$, the local stellar surface density ratio\n$\\Sigma_{\\rm{LDR}}$ and the cumulative distribution of stellar positions.\nINDICATE detects significant differences in the clustering tendencies of the\nmost massive stars when they are at the centre of a smooth, centrally\nconcentrated distribution, corresponding to areas of greater stellar surface\ndensity. When applied to a subset of the 50 most massive stars we show INDICATE\ncan detect signals of mass segregation. We apply INDICATE to the following\nnearby star-forming regions: Taurus, ONC, NGC 1333, IC 348 and $\\rho$ Ophiuchi\nand find a diverse range of clustering tendencies in these regions." }, { "anchor": "Ancient Very Metal-Poor Stars Associated With the Galactic Disk in the\n H3 Survey: Ancient, very metal-poor stars offer a window into the earliest epochs of\ngalaxy formation and assembly. We combine data from the H3 Spectroscopic Survey\nand Gaia to measure metallicities, abundances of $\\alpha$ elements, stellar\nages, and orbital properties of a sample of 482 very metal-poor (VMP;\n[Fe/H]$<-2$) stars in order to constrain their origins. This sample is confined\nto $1\\lesssim |Z| \\lesssim3$ kpc from the Galactic plane. We find that >70% of\nVMP stars near the disk are on prograde orbits and this fraction increases\ntoward lower metallicities. This result unexpected if metal-poor stars are\npredominantly accreted from many small systems with no preferred orientation,\nas such a scenario would imply a mostly isotropic distribution. Furthermore, we\nfind there is some evidence for higher fractions of prograde orbits amongst\nstars with lower [$\\alpha$/Fe]. Isochrone-based ages for main sequence turn-off\nstars reveal that these VMP stars are uniformly old ($\\approx12$ Gyr)\nirrespective of the $\\alpha$ abundance and metallicity, suggesting that the\nmetal-poor population was not born from the same well-mixed gas disk. We\nspeculate that the VMP population has a heterogeneous origin, including both\nin-situ formation in the ancient disk and accretion from a satellite with the\nsame direction of rotation as the ancient disk at early times. Our precisely\nmeasured ages for these VMP stars on prograde orbits show that the Galaxy has\nhad a relatively quiescent merging history over most of cosmic time, and\nimplies the angular momentum alignment of the Galaxy has been in place for at\nleast 12 Gyr.", "positive": "Simulating the formation of massive seed black holes in the early\n Universe. II: Impact of rate coefficient uncertainties: We investigate how uncertainties in the chemical and cooling rate\ncoefficients relevant for a metal-free gas influence our ability to determine\nthe critical ultraviolet field strength required to suppress H2 cooling in\nhigh-redshift atomic cooling halos. The suppression of H2 cooling is a\nnecessary prerequisite for the gas to undergo direct collapse and form an\nintermediate mass black hole. These black holes can then act as seeds for the\ngrowth of the supermassive black holes (SMBHs) observed at redshifts $z \\sim\n6$. The viability of this model for SMBH formation depends on the critical\nultraviolet field strength, Jcrit: if this is too large, then too few seeds\nwill form to explain the observed number density of SMBHs. We show in this\npaper that there are five key chemical reactions whose rate coefficients are\nuncertain enough to significantly affect Jcrit. The most important of these is\nthe collisional ionization of hydrogen by collisions with other hydrogen atoms,\nas the rate for this process is very poorly constrained at the low energies\nrelevant for direct collapse. The total uncertainty introduced into Jcrit by\nthis and the other four reactions could in the worst case approach a factor of\nfive. We also show that the use of outdated or inappropriate values for the\nrates of some chemical reactions in previous studies of the direct collapse\nmechanism may have significantly affected the values of Jcrit determined by\nthese studies." }, { "anchor": "Search for Extratidal Features Around 17 Globular Clusters in the Sloan\n Digital Sky Survey: The dynamical evolution of a single globular cluster and also of the entire\nGalactic globular cluster system has been studied theoretically in detail. In\nparticular, simulations show how the 'lost' stars are distributed in tidal\ntails emerging from the clusters. We investigate the distribution of Galactic\nglobular cluster stars on the sky to identify such features like tidal tails.\nThe Sloan Digital Sky Survey provides consistent photometry of a large part of\nthe sky to study the projected two dimensional structure of the 17 globular\nclusters in its survey area. We use a color-magnitude weighted counting\nalgorithm to map (potential) cluster member stars on the sky. We recover the\nalready known tidal tails of Pal 5 and NGC 5466. For NGC 4147 we have found a\ntwo arm morphology. Possible indications of tidal tails are also seen around\nNGC 5053 and NGC 7078, supporting earlier suggestions. Moreover, we find\npotential tails around NGC 5904 and Pal 14. Especially for the Palomar clusters\nthan Pal 5, deeper data are needed in order to confirm or to rule out the\nexistence of tails. For many of the remaining clusters in our sample we observe\na pronounced extratidal halo, which is particularly large for NGC 7006 and Pal\n1. In some cases, the extratidal halos may be associated with the stream of the\nSagittarius dwarf spheroidal galaxy (e.g.,NGC 4147, NGC 5024, NGC 5053).", "positive": "Taking a Long Look: A Two-Decade Reverberation Mapping Study of\n High-Luminosity Quasars: Reverberation mapping (RM) of active galactic nuclei (AGNs) has been used\nover the past three decades to determine AGN broad-line region (BLR) sizes and\ncentral black-hole masses, and their relations with the AGN's luminosity. Until\nrecently the sample of objects with RM data was limited to low-luminosity AGNs\n($L_{\\rm opt} \\lesssim 10^{46}$ ergs s$^{-1}$) and low redshifts ($z \\lesssim\n0.5$). Here we present results from a reverberation-mapping project of some of\nthe most luminous and highest redshift quasars that have been mapped to date.\nThe study is based on almost twenty years of photometric monitoring of 11\nquasars, six of which were monitored spectrophotometrically for 13 years. This\nis the longest reverberation-mapping project carried out so far on this type of\nAGNs. We successfully measure a time lag between the CIV$\\lambda$1549 broad\nemission line and the quasar continuum in three objects, and measure a\nCIII$\\lambda$1909 lag in one quasar. Together with recently published data on\nCIV reverberation mapping, the BLR size is found to scale as the square root of\nthe UV luminosity over eight orders of magnitude in AGN luminosity. There is a\nsignificant scatter in the relation, part of which may be intrinsic to the\nAGNs. Although the CIV line is probably less well suited than Balmer lines for\ndetermination of the mass of the black hole, virial masses are tentatively\ncomputed and in spite of a large scatter we find that the mass of the black\nhole scales as the square root of the UV luminosity." }, { "anchor": "Physics of pulsar radio emission outside of the main pulse: We for the first time propose a physical model of the precursor (PR) and\ninterpulse (IP) components of the radio pulsar profiles. It is based on\npropagation effects in the secondary plasma flow of a pulsar. The components\nare suggested to result from the induced scattering of the main pulse (MP) into\nbackground. The induced scattering appears efficient enough to transfer a\nsignificant part of the MP energy to the background radiation. In the regimes\nof superstrong and moderately strong magnetic field, the scattered components\nare approximately parallel and antiparallel to the velocity of the scattering\nparticles and can be identified with the PR and IP, respectively. The spectral\nevolution, polarization properties, and fluctuation behaviour of the scattered\ncomponents are examined and compared with the observational results. The\nperspectives of the complex profile studies are outlined as well.", "positive": "Inverse Mapping of Polarised Optical Emission from Pulsars : Basic\n Formulation and Determination of Emission Altitude: We present an inverse mapping approach to determining the emission height of\nthe optical photons from pulsars, which is directly constrained by empirical\ndata. The model discussed is for the case of the Crab pulsar. Our method, using\nthe optical Stokes parameters, determines the most likely geometry for emission\nincluding magnetic field inclination angle ($\\alpha$), observers line of sight\nangle ($\\chi$) and emission height. We discuss the computational implementation\nof the approach, along with any physical assumptions made. We find that the\nmost likely emission altitude is at 20% of the light cylinder radius above the\nstellar surface, in the open field region. We also present a general treatment\nof the expected polarisation from synchrotron source with a truncated power law\nspectrum of particles." }, { "anchor": "The central parsecs of M87: jet emission and an elusive accretion disc: We present the first simultaneous spectral energy distribution (SED) of M87\ncore at a scale of 0.4 arcsec ($\\sim 32\\, \\rm{pc}$) across the electromagnetic\nspectrum. Two separate, quiescent, and active states are sampled that are\ncharacterized by a similar featureless SED of power-law form, and that are thus\nremarkably different from that of a canonical active galactic nuclei (AGN) or a\nradiatively inefficient accretion source. We show that the emission from a jet\ngives an excellent representation of the core of M87 core covering ten orders\nof magnitude in frequency for both the active and the quiescent phases. The\ninferred total jet power is, however, one to two orders of magnitude lower than\nthe jet mechanical power reported in the literature. The maximum luminosity of\na thin accretion disc allowed by the data yields an accretion rate of $< 6\n\\times 10^{-5}\\, \\rm{M_\\odot \\, yr^{-1}}$, assuming 10% efficiency. This power\nsuffices to explain M87 radiative luminosity at the jet-frame, it is however\ntwo to three order of magnitude below that required to account for the jet's\nkinetic power. The simplest explanation is variability, which requires the core\npower of M87 to have been two to three orders of magnitude higher in the last\n200 yr. Alternatively, an extra source of power may derive from black hole\nspin. Based on the strict upper limit on the accretion rate, such spin power\nextraction requires an efficiency an order of magnitude higher than predicted\nfrom magnetohydrodynamic simulations, currently in the few hundred per cent\nrange.", "positive": "A Water Maser and Ammonia Survey of GLIMPSE Extended Green Objects\n (EGOs): We present the results of a Nobeyama 45-m water maser and ammonia survey of\nall 94 northern GLIMPSE Extended Green Objects (EGOs), a sample of massive\nyoung stellar objects (MYSOs) identified based on their extended 4.5 micron\nemission. We observed the ammonia (1,1), (2,2), and (3,3) inversion lines, and\ndetect emission towards 97%, 63%, and 46% of our sample, respectively (median\nrms ~50 mK). The water maser detection rate is 68% (median rms ~0.11 Jy). The\nderived water maser and clump-scale gas properties are consistent with the\nidentification of EGOs as young MYSOs. To explore the degree of variation among\nEGOs, we analyze subsamples defined based on MIR properties or maser\nassociations. Water masers and warm dense gas, as indicated by emission in the\nhigher-excitation ammonia transitions, are most frequently detected towards\nEGOs also associated with both Class I and II methanol masers. 95% (81%) of\nsuch EGOs are detected in water (ammonia(3,3)), compared to only 33% (7%) of\nEGOs without either methanol maser type. As populations, EGOs associated with\nClass I and/or II methanol masers have significantly higher ammonia linewidths,\ncolumn densities, and kinetic temperatures than EGOs undetected in methanol\nmaser surveys. However, we find no evidence for statistically significant\ndifferences in water maser properties (such as maser luminosity) among any EGO\nsubsamples. Combining our data with the 1.1 mm continuum Bolocam Galactic Plane\nSurvey, we find no correlation between isotropic water maser luminosity and\nclump number density. Water maser luminosity is weakly correlated with clump\n(gas) temperature and clump mass." }, { "anchor": "A Precise Milky Way Rotation Curve Model for an Accurate Galactocentric\n Distance: I provide a model rotation curve for the Milky Way that matches the details\nof the terminal velocity curve normalized to the Galactocentric distance $R_0 =\n8.122$ kpc obtained by the GRAVITY collaboration and the corresponding circular\nspeed of the LSR $\\Theta_0 = 233.3$ km/s. The model provides a numerical\nrepresentation of the azimuthally averaged radial run of the gravitational\npotential of each mass component of the Galaxy (bulge-bar, stellar disk, gas\ndisk, and dark matter) as represented by the rotation curve of each. It\nprovides precise estimates of quantities like the stellar mass of the Galaxy\n($6.16 \\pm 0.31 \\times 10^{10}\\;\\mathrm{M}_{\\odot}$) and the local density of\ndark matter ($\\rho_{DM}(R_0) = 6.76^{+0.08}_{-0.14} \\times 10^{-3}\\;\n\\mathrm{M}_{\\odot}\\,\\mathrm{pc}^{-3} = 0.257^{+0.003}_{-0.005}\\;\n\\mathrm{GeV}\\,\\mathrm{cm}^{-3}$). The dark matter density implied by the radial\nforce is less than that found in many studies of the vertical force, perhaps\nindicating that the usual assumption of a spherical dark matter halo is no\nlonger adequate.", "positive": "MUSE view of Arp220: Kpc-scale multi-phase outflow and evidence for\n positive feedback: Arp220 is the nearest and prototypical ULIRG, and shows evidence of pc-scale\nmolecular outflows in its nuclear regions and strongly perturbed ionised gas\nkinematics on kpc scales. It is therefore the ideal system for investigating\noutflows and feedback phenomena in details. We investigate the feedback effects\non the Arp220 ISM, deriving a detailed picture of the atomic gas in terms of\nphysical and kinematic properties, with a spatial resolution never obtained\nbefore (0.56\", i.e. ~ 210 pc). We use optical IFS observations from VLT/MUSE-AO\nto obtain spatially resolved stellar and gas kinematics, for both ionised ([N\nII]6583) and neutral (Na ID5891,96) components; we also derive dust\nattenuation, electron density, ionisation conditions and hydrogen column\ndensity maps to characterise the ISM properties. Arp220 kinematics reveal the\npresence of a disturbed, kpc-scale disk in the innermost nuclear regions, and\nhighly perturbed, multi-phase (neutral and ionised) gas along the minor-axis of\nthe disk, which we interpret as a galactic-scale outflow emerging from the\nArp220 eastern nucleus. This outflow involves velocities up to ~ 1000 km/s at\ngalactocentric distances of ~ 5 kpc, and has a mass rate of ~ 50 Msun/yr, and\nkinetic and momentum power of ~ 1e43 erg/s and ~ 1e35 dyne, respectively. The\ninferred energetics do not allow us to distinguish the origin of the outflows,\ni.e. whether they are AGN-driven or starburst-driven. We also present evidence\nfor enhanced star formation at the edges of - and within - the outflow, with a\nstar formation rate SFR ~ 5 Msun/yr (i.e. ~ 2% of the total SFR). Our findings\nsuggest the presence of powerful winds in Arp220: they might be capable of\nremoving or heating large amounts of gas from the host (\"negative feedback\"),\nbut could be also responsible for triggering star formation (\"positive\nfeedback\")." }, { "anchor": "The new semianalytic code GalICS 2.0 - Reproducing the galaxy stellar\n mass function and the Tully-Fisher relation simultaneously: GalICS 2.0 is a new semianalytic code to model the formation and evolution of\ngalaxies in a cosmological context. N-body simulations based on a Planck\ncosmology are used to construct halo merger trees, track subhaloes, compute\nspins and measure concentrations. The accretion of gas onto galaxies and the\nmorphological evolution of galaxies are modelled with prescriptions derived\nfrom hydrodynamic simulations. Star formation and stellar feedback are\ndescribed with phenomenological models (as in other semianalytic codes). GalICS\n2.0 computes rotation speeds from the gravitational potential of the dark\nmatter, the disc and the central bulge. As the rotation speed depends not only\non the virial velocity but also on the ratio of baryons to dark matter within a\ngalaxy, our calculation predicts a different Tully-Fisher relation from models\nin which the rotation speed is proportional to the virial velocity. This is why\nGalICS 2.0 is able to reproduce the galaxy stellar mass function and the\nTully-Fisher relation simultaneously. Our results are also in agreement with\nhalo masses from weak lensing and satellite kinematics, gas fractions, the\nrelation between star formation rate (SFR) and stellar mass, the evolution of\nthe cosmic SFR density, bulge-to-disc ratios, disc sizes and the Faber-Jackson\nrelation.", "positive": "Probing the anisotropy of the Milky Way gaseous halo: Sight-lines toward\n Mrk 421 and PKS2155-304: (Abridged) We recently found that the halo of the Milky Way contains a large\nreservoir of warm-hot gas that contains a large fraction of the missing baryons\nfrom the Galaxy. The average physical properties of this circumgalactic medium\n(CGM) are determined by combining average absorption and emission measurements\nalong several extragalactic sightlines. However, there is a wide distribution\nof both, the halo emission measure and the \\ovii column density, suggesting\nthat the Galactic warm-hot gaseous halo is anisotropic. We present {\\it Suzaku}\nobservations of fields close to two sightlines along which we have precise\n\\ovii absorption measurements with \\chandran. The column densities along these\ntwo sightlines are similar within errors, but we find that the emission\nmeasures are different. Therefore the densities and pathlengths in the two\ndirections must be different, providing a suggestive evidence that the warm-hot\ngas in the CGM of the Milky Way is not distributed uniformly. However, the\nformal errors on derived parameters are too large to make such a claim. The\naverage density and pathlength of the two sightlines are similar to the global\naverages, so the halo mass is still huge, over 10 billion solar masses. With\nmore such studies, we will be able to better characterize the CGM anisotropy\nand measure its mass more accurately. We also show that the Galactic disk makes\ninsignificant contribution to the observed \\ovii absorption; a similar\nconclusion was also reached independently about the emission measure. We\nfurther argue that any density inhomogeneity in the warm-hot gas, be it from\nclumping, from the disk, or from a non-constant density gradient, would\nstrengthen our result in that the Galactic halo path-length and the mass would\nbecome larger than what we estimate here. As such, our results are conservative\nand robust." }, { "anchor": "Water in star-forming regions with Herschel (WISH). IV. A survey of\n low-J H2O line profiles toward high-mass protostars: To understand the origin of water line emission and absorption during\nhigh-mass star formation, we decompose high-resolution Herschel-HIFI line\nspectra toward 19 high-mass star-forming regions into three distinct physical\ncomponents. Protostellar envelopes are usually seen as narrow absorptions or\nemissions in the H2O 1113 and 1669 GHz ground-state lines, the H2O 987 GHz\nexcited-state line, and the H2O-18 1102 GHz ground-state line. Broader features\ndue to outflows are usually seen in absorption in the H2O 1113 and 1669 GHz\nlines, in 987 GHz emission, and not seen in H2O-18, indicating a low column\ndensity and a high excitation temperature. The H2O 1113 and 1669 GHz spectra\nshow narrow absorptions by foreground clouds along the line of sight, which\nhave a low column density and a low excitation temperature, although their H2O\northo/para ratios are close to 3.\n The intensities of the H2O 1113 and 1669 GHz lines do not show significant\ntrends with luminosity, mass, or age. In contrast, the 987 GHz line flux\nincreases with luminosity and the H2O-18 line flux decreases with mass.\nFurthermore, appearance of the envelope in absorption in the 987 GHz and H2O-18\nlines seems to be a sign of an early evolutionary stage.\n We conclude that the ground state transitions of H2O trace the outer parts of\nthe envelopes, so that the effects of star formation are mostly noticeable in\nthe outflow wings. These lines are heavily affected by absorption, so that line\nratios of H2O involving the ground states must be treated with caution. The\naverage H2O abundance in high-mass protostellar envelopes does not change much\nwith time. The 987 GHz line appears to be a good tracer of the mean weighted\ndust temperature of the source, which may explain why it is readily seen in\ndistant galaxies.", "positive": "Giant Biconical Dust Filaments in the Starburst Galaxy NGC 1808: We present the results from an analysis of multi-wavelength archival data on\nthe multi-phase outflow in the starburst galaxy NGC 1808. We report the\ndetection at 70 and 100 um of dust filaments that extend up to ~ 13 kpc from\nthe galactic mid-plane and trace an edge-brightened biconical structure along\nthe minor axis of the galaxy. The inner filaments are roughly co-spatial with\npreviously identified optical dust filaments, extraplanar polycyclic aromatic\nhydrocarbon emission, and neutral and ionized gaseous outflows. The 70/160 um\nflux ratio, a proxy for dust temperature, is elevated along the edges of the\ncones, indicating that the dusty medium has been driven out of the central\nregions of these cones and possibly shock-heated by an outflow. We establish\nlower limits on the extraplanar dust mass and mean height above the stellar\ndisk of log(M_d/M_sun) = 6.48 and |z| ~ 5 kpc, respectively. The energy\nrequirement of (5.1-9.6) x 10^{56} ergs needed to lift the dusty material,\nassuming Milky-Way like dust-to-gas ratio, can be supplied by the current\nstarburst, with measured star formation rate of 3.5-5.4 M_sun yr^{-1}, over a\ntimescale of (4-26) xi^{-1} Myr, where xi is the efficiency of energy transfer.\nWe conclude that a starburst-driven outflow is the most likely mechanism by\nwhich the dust features were formed." }, { "anchor": "The Coevolution of Massive Quiescent Galaxies and Their Dark Matter\n Halos over the Last 6 Billion Years: We investigate the growth of massive quiescent galaxies at $z<0.6$ based on\nthe Sloan Digital Sky Survey and the Smithsonian Hectospec Lensing Survey---two\nmagnitude limited spectroscopic surveys of high data quality and completeness.\nOur three parameter model links quiescent galaxies across cosmic time by\nself-consistently evolving stellar mass, stellar population age sensitive\n$D_n4000$ index, half-light radius and stellar velocity dispersion. Stellar\nvelocity dispersion is a robust proxy of dark matter halo mass; we use it to\nconnect galaxies and dark matter halos and thus empirically constrain their\ncoevolution. The typical rate of stellar mass growth is $\\sim \\! 10 \\,\\,\nM_\\odot \\,\\, \\mathrm{yr}^{-1}$ and dark matter growth rates from our empirical\nmodel are remarkably consistent with N-body simulations. Massive quiescent\ngalaxies grow by minor mergers with dark matter halos of mass $10^{10} \\,\\,\nM_\\odot \\lesssim M_{DM} \\lesssim 10^{12} \\,\\, M_\\odot$ and evolve parallel to\nthe stellar mass-halo mass relation based on N-body simulations. Thus, the\nstellar mass-halo mass relation of massive galaxies apparently results\nprimarily from dry minor merging.", "positive": "The COS-legacy survey of C IV absorbers: properties and origins of the\n intervening systems: We present here results from a survey of intervening C IV absorbers at $z <\n0.16$ conducted using 223 sightlines from the Hubble Spectroscopic Legacy\nArchive. Most systems (83%) out of the total sample of 69 have simple\nkinematics with 1 or 2 C IV components. In the 22 C IV systems with well\nconstrained H I column densities, the temperatures from the $b$-values imply\npredominantly photoionized plasma ($T\\leq 10^5$ K) and non-thermal dynamics.\nThese systems also have solar or higher metallicities. We obtain a C IV line\ndensity of $d\\mathcal{N}/dX = 5.1\\pm 1.0$ for $\\log\n[N(C~IV)~(cm^{-2})]\\geq12.9$, and $\\Omega_{C~IV}=(8.01\\pm 1.62) \\times 10^{-8}$\nfor $12.9 \\leq \\log [N(C~IV)~(cm^{-2})] \\leq 15.0$. The C IV bearing diffuse\ngas in the $z < 0.16$ Universe has a metallicity of\n$(2.07~{\\pm}~0.43)~\\times~10^{-3}$ Z$_{\\odot}$, an order of magnitude more than\nthe metal abundances in the IGM at high redshifts ($z \\gtrsim 5$), and\nconsistent with the slow build-up of metals in the diffuse circum/intergalactic\nspace with cosmic time. For $z<0.015$ (complete above $L>0.01L^\\star$), the\nSloan Digital Sky Survey provides a tentative evidence of declining covering\nfraction for strong C IV ($N>10^{13.5}~cm^{-2}$) with $\\rho$ (impact parameter)\nand $\\rho/R_\\mathrm{vir}$. However, the increase at high separations suggests\nthat strong systems are not necessarily coincident with such galaxies. We also\nfind that strong C IV absorption at $z<0.051$ is not coincident with galaxy\nover-dense regions complete for $L>0.13L^\\star$" }, { "anchor": "Searching Far and Long I: Pilot ALMA 2mm Follow-up of Bright Dusty\n Galaxies as a Redshift Filter: A complete census of dusty star-forming galaxies (DSFGs) at early epochs is\nnecessary to constrain the obscured contribution to the cosmic star formation\nrate density (CSFRD), however DSFGs beyond $z \\sim 4$ are both rare and hard to\nidentify from photometric data alone due to degeneracies in submillimeter\nphotometry with redshift. Here, we present a pilot study obtaining follow-up\nAtacama Large Millimeter Array (ALMA) $2\\,$mm observations of a complete sample\nof 39 $850\\,\\rm\\mu m$-bright dusty galaxies in the SSA22 field. Empirical\nmodeling suggests $2\\,$mm imaging of existing samples of DSFGs selected at\n$850\\,\\rm\\mu m - 1\\,$mm can quickly and easily isolate the \"needle in a\nhaystack\" DSFGs that sit at $z>4$ or beyond. Combining archival submillimeter\nimaging with our measured ALMA $2\\,$mm photometry ($1\\sigma \\sim\n0.08\\,$mJy$\\,$beam$^{-1}$ rms), we characterize the galaxies' IR SEDs and use\nthem to constrain redshifts. With available redshift constraints fit via the\ncombination of six submillimeter bands, we identify 6/39 high-$z$ candidates\neach with $>50\\%$ likelihood to sit at $z > 4$, and find a positive correlation\nbetween redshift and $2\\,$mm flux density. Specifically, our models suggest the\naddition of $2\\,$mm to a moderately constrained IR SED will improve the\naccuracy of a millimeter-derived redshift from $\\Delta z/(1+z) = 0.3$ to\n$\\Delta z/(1+z) = 0.2$. Our IR SED characterizations provide evidence for\nrelatively high emissivity spectral indices ($\\langle \\beta \\rangle =\n2.4\\pm0.3$) in the sample. We measure that especially bright ($S_{850\\rm\\mu\nm}>5.55\\,$mJy) DSFGs contribute $\\sim10$% to the cosmic-averaged CSFRD from\n$210^10.5 M_sun) and that the observed fraction of\ngalaxies hosting an AGN increases with the stellar mass. A careful selection of\nrandom control samples of inactive galaxies allows us to remove the stellar\nmass and redshift dependencies of the AGN fraction to explore trends with\nseveral stellar age indicators. We find no significant differences in the\ndistribution of the rest-frame U-V colour for AGN hosts and inactive galaxies,\nin agreement with previous results. However, we find significantly shallower\n4000 AA breaks in AGN hosts, indicative of younger stellar populations. With\nthe help of a model-independent determination of the extinction, we obtain\nextinction-corrected U-V colours and light-weighted average stellar ages. We\nfind that AGN hosts have younger stellar populations and higher extinction\ncompared to inactive galaxies with the same stellar mass and at the same\nredshift. We find a highly significant excess of AGN hosts with Dn(4000)~1.4\nand light weighted average stellar ages of 300-500 Myr, as well as a deficit of\nAGN in intrinsic red galaxies. We interpret failure in recognising these trends\nin previous studies as a consequence of the balancing effect in observed\ncolours of the age-extinction degeneracy.", "positive": "X-ray Scaling Relations of core and coreless E and S0 Galaxies: We have re-examined the two X-ray scaling relations of early-type galaxies\n(ETGs), Lx - LK and Lx - T, using 61 ATLAS3D E and S0 galaxies observed with\nChandra. The larger sample allows us to investigate the effect of structural\nand dynamical properties of ETGs in these relations. Using the sub-sample of\ngenuine E galaxies with central surface brightness cores, slow stellar\nrotations and old stellar populations, we find that the scatter of the\ncorrelations is strongly reduced, yielding an extremely tight relation. For the\ngas-rich galaxies in this sample, this relation is consistent with recent\nsimulations. However, the tight Lx - T relation of genuine E galaxies extends\ndown into the Lx 1038 erg s-1 range, where simulations predict the gas to be in\noutflow/wind state. The observed correlation may suggest the presence of small\nbound hot halos even in this low luminosity range. At the high luminosity end,\nthe Lx - T correlation of core elliptical galaxies is similar to that found in\nsamples of cD galaxies and groups, but shifted down toward lower Lx. In\nparticular cDs have an order of magnitude higher Lx than core galaxies for the\nsame LK and T. We suggest that enhanced cooling in cDs could lower T to the\nrange observed in giant Es; this conclusion is supported by the presence of\nextended cold gas in several cDs. Instead, in the sub-sample of coreless ETGs,\nLx and T are not correlated, suggesting that both the energy input from star\nformation and the effect of galactic rotation and flattening may disrupt the\nhot ISM." }, { "anchor": "Hyperfine structure in the J = 1-0 transitions of DCO+, DNC, and HN13C:\n astronomical observations and quantum-chemical calculations: We have observed the rotational ground-state (J = 1-0) transitions of DCO+,\nHN13C and DNC with the IRAM 30m telescope toward the dark cloud LDN 1512 which\nhas exceptionally narrow lines permitting hyperfine splitting to be resolved in\npart. The measured splittings of 50-300 kHz are used to derive nuclear\nquadrupole and spin-rotation parameters for these species. The measurements are\nsupplemented by high-level quantum-chemical calculations using coupled-cluster\ntechniques and large atomic-orbital basis sets.\n We find eQq = +151.12 (400) kHz and C_I = -1.12 (43) kHz for DCO+, eQq =\n272.5 (51) kHz for HN13C, and eQq(D) = 265.9 (83) kHz and eQq(N) = 288.2 (71)\nkHz for DNC. The numbers for DNC are consistent with previous laboratory data,\nwhile our constants for DCO+ are somewhat smaller than previous results based\non astronomical data. For both DCO+ and DNC, our results are more accurate than\nprevious determinations. Our results are in good agreement with the\ncorresponding best theoretical estimates. We also derive updated rotational\nconstants for HN13C: B = 43545.6000 (47) MHz and D = 93.7 (20) kHz.\n The hyperfine splittings of the DCO+, DNC and HN13C J = 1-0 lines range over\n0.47-1.28 km/s, which is comparable to typical line widths in pre-stellar cores\nand to systematic gas motions on ~1000 AU scales in protostellar cores. We\npresent tabular information to allow inclusion of the hyperfine splitting in\nastronomical data interpretation. The large differences in the 14N quadrupole\nparameters of DNC and HN13C have been traced to differences in the vibrational\ncorrections caused by significant non-rigidity of these molecules, particularly\nalong the bending coordinate.", "positive": "The Mid-Infrared Colours of Galactic Bulge, Disk and Magellanic\n Planetary Nebulae: We present mid-infrared (MIR) photometry for 367 Galactic disk, bulge and\nLarge Magellanic Cloud (LMC) planetary nebulae, determined using GLIMPSE II and\nSAGE data acquired using the Spitzer Space Telescope. This has permitted us to\nmake a comparison between the luminosity functions of bulge and LMC planetary\nnebulae, and between the MIR colours of all three categories of source. It is\ndetermined that whilst the 3.6 microns luminosity function of the LMC and bulge\nsources are likely to be closely similar, the [3.6]-[5.8] and [5.8]-[8-0]\nindices of LMC nebulae are different from those of their disk and bulge\ncounterparts. This may arise because of enhanced 6.2 microns PAH emission\nwithin the LMC sources, and/or as a result of differences between the spectra\nof LMC PNe and those of their Galactic counterparts. We also determine that the\nmore evolved disk sources listed in the MASH catalogues of Parker et al. and\nMiszalski et al. (2008) have similar colours to those of the less evolved (and\nhigher surface brightness) sources in the catalogue of Acker et al. (1992); a\nresult which appears at variance with previous studies of these sources." }, { "anchor": "Multi-Wavelength Study of a Proto-BCG at z = 1.7: In this work we performed a spectral energy distribution (SED) analysis in\nthe optical/infrared band of the host galaxy of a proto-brightest cluster\ngalaxy (BCG, NVSS J103023+052426) in a proto-cluster at z = 1.7. We found that\nit features a vigorous star formation rate (SFR) of ${\\sim}$570\n$\\mathrm{M_{\\odot}}$/yr and a stellar mass of $M_{\\ast} \\sim 3.7 \\times\n10^{11}$ $\\mathrm{M_{\\odot}}$; the high corresponding specific SFR = $1.5 \\pm\n0.5$ $\\mathrm{Gyr^{-1}}$ classifies this object as a starburst galaxy that will\ndeplete its molecular gas reservoir in $\\sim$ $3.5 \\times 10^8$ yr. Thus, this\nsystem represents a rare example of a proto-BCG caught during the short phase\nof its major stellar mass assembly. Moreover, we investigated the nature of the\nhost galaxy emission at 3.3 mm. We found that it originates from the cold dust\nin the interstellar medium, even though a minor non-thermal AGN contribution\ncannot be completely ruled out. Finally, we studied the polarized emission of\nthe lobes at 1.4 GHz. We unveiled a patchy structure where the polarization\nfraction increases in the regions in which the total intensity shows a bending\nmorphology; in addition, the magnetic field orientation follows the direction\nof the bendings. We interpret these features as possible indications of an\ninteraction with the intracluster medium. This strengthens the hypothesis of\npositive AGN feedback, as inferred in previous studies of this object on the\nbasis of X-ray/mm/radio analysis. In this scenario, the proto-BCG heats the\nsurrounding medium and possibly enhances the SFR in nearby galaxies.", "positive": "The physical parameters of clumps associated with class I methanol\n masers: We present a study of the association between class I methanol masers and\ncold dust clumps from the ATLASGAL survey. It was found that almost 100% of\nclass I methanol masers are associated with objects listed in the ATLASGAL\ncompact source catalog. We find a statistically significant difference in the\nflux density, luminosity, number and column density and temperature\ndistributions of ATLASGAL sources associated with 95/44 GHz methanol masers\ncompared with those ATLASGAL sources devoid of 95 GHz methanol masers. The\nmasers tend to arise in clumps with higher densities, luminosities and\ntemperatures compared with both the full sample of the ATLASGAL clumps, as well\nas the sample of ATLASGAL sources that were cross-matched with positions\npreviously searched for methanol masers but with no detections. Comparison\nbetween the peak position of ATLASGAL clumps and the interferometric positions\nof the associated class I and II methanol masers reveals that class I masers\nare generally located at larger physical distances from the peak submillimetre\nemission than class II masers. We conclude that the tight association between\nATLASGAL sources and class I methanol masers may be used as a link toward\nunderstanding the conditions of the pumping of these masers and evolutionary\nstages at which they appear." }, { "anchor": "A bathtub model for the star-forming interstellar medium: The bathtub model of the star forming interstellar medium is based on the\npowerful constraint that mass has to be conserved when gas flows through its\nvarious thermal and density phases, ending up eventually in a young star or\nbeing blown away by stellar feedback. It predicts that the star formation rate\nof a molecular cloud is not determined by the cloud's mass or its internal\ncollapse timescale, but rather by the accretion rate of new gas. For the most\nsimple case of a constant accretion flow an equilibrium state is reached\nquickly where the star formation rate equals the accretion rate and where the\ndense gas mass is constant and independent of time. The mass of the young star\ncluster, on the other hand, increases linearly with time. The stellar mass\nfraction therefore represents a sensitive clock to measure the age of the\nstar-forming region. The bathtub model predicts that the efficiency of star\nformation is small, of order 1%, even in the dense filamentary phases of\nmolecular clouds. It provides a simple explanation for the dense gas fraction\nof order 10% in molecular clouds and for the large gas depletion timescales of\nstar-forming galaxies of order $5 \\times 10^8 - 10^9$ yrs.", "positive": "On the role of dust in the microwave emission of galactic halos: The contribution of the thermal dust component in galactic halo rotation is\nexplored based on the microwave data of Planck satellite. The temperature\nasymmetry of Doppler nature revealed for several edge-on galaxies at several\nmicrowave frequencies is analyzed regarding the contribution of the thermal\ndust emission. We derive the dust contribution to the galactic halo rotation\nusing the data in three bands, 353GHz, 545GHz and 857GHz for two nearby\ngalaxies M81 and M82. The relevance of the revealed properties on the halo\nrotation is then discussed in the context of the modified gravity theories\nproposed to describe the dark matter configurations." }, { "anchor": "Predicted MOND velocity dispersions for a catalog of ultra-diffuse\n galaxies in group environments: The possibility that ultra-diffuse galaxies lacking dark matter has recently\nstimulated interest to check the validity of Modified Newton Dynamics (MOND)\npredictions on the scale of such galaxies. It has been shown that the External\nField Effect (EFE) induced by the close-by galaxy can suppress the velocity\ndispersion of these systems, so that they appear almost dark matter free in the\nNewtonian context. Here, following up on this, we are making a priori\npredictions for the velocity dispersion of 22 ultra-diffuse galaxies in the\nnearby Universe. This sample can be used to test MOND and the EFE with future\nfollow-up measurements. We construct a catalog of nearby ultra-diffuse galaxies\nin galaxy group environments, and set upper and lower limits for the possible\nvelocity dispersion allowed in MOND, taking into account possible variations in\nthe mass-to-light ratio of the dwarf and in the distance to the galaxy group.\nThe prediction for the velocity dispersion is made as a function of the three\ndimensional separation of the dwarf to its host. In 17 out of 22 cases, the EFE\nplays a crucial role in the prediction.", "positive": "Dynamical evolution of star forming regions: We model the dynamical evolution of star forming regions with a wide range of\ninitial properties. We follow the evolution of the regions' substructure using\nthe Q-parameter, we search for dynamical mass segregation using the Lambda_MSR\ntechnique, and we also quantify the evolution of local density around stars as\na function of mass using the Sigma_LDR method.\n The amount of dynamical mass segregation measured by Lambda_MSR is generally\nonly significant for subvirial and virialised, substructured regions - which\nusually evolve to form bound clusters. The Sigma_LDR method shows that massive\nstars attain higher local densities than the median value in all regions, even\nthose that are supervirial and evolve to form (unbound) associations.\n We also introduce the Q-Sigma_LDR plot, which describes the evolution of\nspatial structure as a function of mass-weighted local density in a star\nforming region. Initially dense (>1000 stars pc^{-2}), bound regions always\nhave Q >1, Sigma_LDR > 2 after 5Myr, whereas dense unbound regions always have\nQ < 1, Sigma_LDR > 2 after 5Myr. Less dense regions (<100 stars pc^{-2}) do not\nusually exhibit Sigma_LDR > 2 values, and if relatively high local density\naround massive stars arises purely from dynamics, then the Q-Sigma_LDR plot can\nbe used to estimate the initial density of a star forming region." }, { "anchor": "K-Band Imaging of the Nearby, Clumpy Turbulent Disk Galaxy DYNAMO G04-1: We present a case study of stellar clumps in G04-1, a clumpy, turbulent disk\ngalaxy located at $z$ = 0.13 from the DYNAMO sample, using adaptive optics\nenabled K-band imaging ($\\sim2.25$ kpc/arcsec) with Keck/NIRC2. We identify 15\nstellar clumps in G04-1 with a range of masses from $3.6 \\times 10^{6}$ to $2.7\n\\times 10^{8}\\ \\rm M_{\\odot}$, and with a median mass of $\\sim2.9 \\times\n10^{7}\\ \\rm M_{\\odot}$. Note that these masses decrease by about one-half when\nwe apply a light correction for the underlying stellar disk. A majority (12 of\n15) of clumps observed in the $K_{P}$-band imaging have associated components\nin H$\\alpha$ maps ($\\sim2.75$ kpc/arcsec; $<$R$_{clump}> \\sim$500 pc) and\nappear co-located ($\\overline{\\Delta x} \\sim 0.1$ arcsec). Using Hubble Space\nTelescope WFC/ACS observations with the F336W and F467M filters, we also find\nevidence of radial trends in clump stellar properties: clumps closer to the\ncentre of G04-1 are more massive (consistent with observations at high-$z$) and\nappear more red, suggesting they may be more evolved. Using our high-resolution\ndata, we construct a star forming main sequence for G04-1 in terms of\nspatially-resolved quantities and find that all regions (both clump and\nintra-clump) within the galaxy are experiencing an enhanced mode of star\nformation routinely observed in galaxies at high-$z$. In comparison to recent\nsimulations, our observation of a number of clumps with masses $10^{7}-10^{8}\\\n\\rm M_{\\odot}$ is not consistent with strong radiative feedback in this galaxy.", "positive": "The SINFONI Nearby Elliptical Lens Locator Survey: Discovery of two new\n low-redshift strong lenses and implications for the initial mass function in\n giant early-type galaxies: We present results from a blind survey to identify strong gravitational\nlenses among the population of low-redshift early-type galaxies. The SINFONI\nNearby Elliptical Lens Locator Survey (SNELLS) uses integral-field infrared\nspectroscopy to search for lensed emission line sources behind massive lens\ncandidates at $z$<0.055. From 27 galaxies observed, we have recovered one\npreviously-known lens (ESO325-G004) at $z$=0.034, and discovered two new\nsystems, at $z$=0.031 and $z$=0.052. All three lens galaxies have high velocity\ndispersions (\\sigma>300 km/s) and \\alpha-element abundances ([Mg/Fe]>0.3). From\nthe lensing configurations we derive total J-band mass-to-light ratios of\n1.8$\\pm$0.1, 2.1$\\pm$0.1 and 1.9$\\pm$0.2 within the $\\sim$2 kpc Einstein\nradius. Correcting for estimated dark-matter contributions, and comparing to\nstellar population models with a Milky Way (Kroupa) initial mass function\n(IMF), we determine the \"mass excess factor\", \\alpha. Assuming the lens\ngalaxies have \"old\" stellar populations (10$\\pm$1 Gyr), the average IMF mass\nfactor is $\\langle\\alpha\\rangle$=1.10$\\pm$0.08$\\pm$0.10, where the first error\nis random and the second is systematic. If we instead fit the stellar\npopulations from 6dF optical survey spectra, all three galaxies are consistent\nwith being old, but the age errors are 3-4 Gyr, due to limited signal-to-noise.\nThe IMF constraints are therefore looser in this case, with\n$\\langle\\alpha\\rangle$ = $1.23^{+0.16}_{-0.13}\\pm{0.10}$. Our results are thus\nconsistent with a Kroupa IMF (\\alpha=1.00) on average, and strongly reject very\nheavy IMFs with \\alpha>2. A Salpeter IMF (\\alpha=1.55) is inconsistent at the\n3.5$\\sigma$ level if the galaxies are old, but cannot be excluded using age\nconstraints derived from the currently-available optical spectra." }, { "anchor": "Identifying Bright Stars in Crowded Environments Using Velocity\n Dispersion Measurements, and an Application to the Center of M32: The identification of individual stars in crowded environments using\nphotometric information alone is confounded by source confusion. However, with\nthe addition of spectroscopic information it is possible to distinguish between\nblends and areas where the light is dominated by a single star using the widths\nof absorption features. We describe a procedure for identifying locations in\nkinematically hot environments where the light is dominated by a single star,\nand apply this method to spectra with 0.1 arcsec angular resolution covering\nthe 2.1 - 2.3 micron interval in the central regions of M32. Targets for\ndetailed investigation are selected as areas of localized brightness\nenhancement. Three locations where at least 60% of the K-band light comes from\na single bright star, and another with light that is dominated by two stars\nwith very different velocities, are identified. The dominant stars are evolving\nnear the tip of the asymptotic giant branch (AGB), and have M5 III spectral\ntype. The lack of a dispersion in spectral-type suggests that the upper AGB\nwithin the central arcsec of M32 has a dispersion in J-K of only a few\nhundreths of a magnitude, in agreement with what is seen at larger radii. One\nstar has weaker atomic absorption lines than the others, such that [M/H] is 0.2\ndex lower. Such a difference in metallicity is consistent with the metallicity\ndispersion inferred from the width of the AGB in M32. The use of line width to\ndistinguish between blends involving many relatively faint stars, none of which\ndominate the light output, and areas that are dominated by a single\nintrinsically bright star could be extended to crowded environments in other\nnearby galaxies.", "positive": "Emission Measures and Emission-measure-weighted Temperatures of Shocked\n ISM and Ejecta in Supernova Remnants: A goal of supernova remnant (SNR) evolution models is to relate fundamental\nparameters of a supernova (SN) explosion and progenitor star to the current\nstate of its SNR. The SNR hot plasma is characterized by its observed X-ray\nspectrum, which yields electron temperature, emission measure and abundances.\nDepending on their brightness, the properties of the plasmas heated by the SNR\nforward shock, reverse shock or both can be measured. The current work utilizes\nmodels which are spherically symmetric. One dimensional hydrodynamic\nsimulations are carried out for SNR evolution prior to onset of radiative\nlosses. From these, we derive dimensionless emission measures and\nemission-measure-weighted temperatures, and we present fitting formulae for\nthese quantities as functions of scaled SNR time. These models allow one to\ninfer SNR explosion energy, circumstellar medium density, age, ejecta mass and\nejecta density profile from SNR observations. The new results are incorporated\ninto the SNR modelling code SNRPy. The code is demonstrated with application to\nthree historical SNRs: Kepler, Tycho and SN1006." }, { "anchor": "A Study of Central Galaxy Rotation with Stellar Mass and Environment: We present a pilot analysis of the influence of galaxy stellar mass and\ncluster environment on the probability of slow rotation in 22 central galaxies\nat mean redshift $z=0.07$. This includes new integral-field observations of 5\ncentral galaxies selected from the Sloan Digital Sky Survey, observed with the\nSPIRAL integral-field spectrograph on the Anglo-Australian Telescope. The\ncomposite sample presented here spans a wide range of stellar masses,\n$10.9<$log(M$_{*}/$M$_{\\odot})<12.0$, and are embedded in halos ranging from\ngroups to clusters, $12.9<$log(M$_{200}/$M$_{\\odot})<15.6$. We find a mean\nprobability of slow rotation in our sample of P(SR)$=54\\pm7$percent. Our\nresults show an increasing probability of slow rotation in central galaxies\nwith increasing stellar mass. However, when we examine the dependence of slow\nrotation on host cluster halo mass we do not see a significant relationship. We\nalso explore the influence of cluster dominance on slow rotation in central\ngalaxies. Clusters with low dominance are associated with dynamically younger\nsystems. We find that cluster dominance has no significant effect on the\nprobability of slow rotation in central galaxies. These results conflict with a\nparadigm in which halo mass alone predetermines central galaxy properties.", "positive": "From cusps to cores: a stochastic model: The cold dark matter model of structure formation faces apparent problems on\ngalactic scales. Several threads point to excessive halo concentration,\nincluding central densities that rise too steeply with decreasing radius. Yet,\nrandom fluctuations in the gaseous component can 'heat' the centres of haloes,\ndecreasing their densities. We present a theoretical model deriving this effect\nfrom first principles: stochastic variations in the gas density are converted\ninto potential fluctuations that act on the dark matter; the associated force\ncorrelation function is calculated and the corresponding stochastic equation\nsolved. Assuming a power law spectrum of fluctuations with maximal and minimal\ncutoff scales, we derive the velocity dispersion imparted to the halo particles\nand the relevant relaxation time. We further perform numerical simulations,\nwith fluctuations realised as a Gaussian random field, which confirm the\nformation of a core within a timescale comparable to that derived analytically.\nNon-radial collective modes enhance the energy transport process that erases\nthe cusp, though the parametrisations of the analytical model persist.\n In our model, the dominant contribution to the dynamical coupling driving the\ncusp-core transformation comes from the largest scale fluctuations. Yet, the\nefficiency of the transformation is independent of the value of the largest\nscale and depends weakly (linearly) on the power law exponent; it effectively\ndepends on two parameters: the gas mass fraction and the normalisation of the\npower spectrum. This suggests that cusp-core transformations observed in\nhydrodynamic simulations of galaxy formation may be understood and parametrised\nin simple terms, the physical and numerical complexities of the various\nimplementations notwithstanding." }, { "anchor": "Chemical abundance patterns in the inner Galaxy: the Scutum Red\n Supergiant Clusters: The location of the Scutum Red-Supergiant (RSG) clusters at the end of the\nGalactic Bar makes them an excellent probe of the Galaxy's secular evolution;\nwhile the clusters themselves are ideal testbeds in which to study the\npredictions of stellar evolutionary theory. To this end, we present a study of\nthe RSGs' surface abundances using a combination of high-resolution H-band\nspectroscopy and spectral synthesis analysis. We provide abundance measurements\nfor elements C, O, Si, Mg, Ti, and Fe. We find that the surface abundances of\nthe stars studied are consistent with CNO burning and deep, rotationally\nenhanced mixing. The average a/Fe ratios of the clusters are solar, consistent\nwith a thin-disk population. However, we find significantly sub-solar Fe/H\nratios for each cluster, a result which strongly contradicts a simple\nextrapolation of the Galactic metallicity gradient to lower Galacto-centric\ndistances. We suggest that a simple one-dimensional parameterization of the\nGalaxy's abundance patterns is insufficient at low Galactocentric distances, as\nlarge azimuthal variations may be present. Indeed, we show that the abundances\nof O, Si and Mg are consistent with independent measurements of objects in\nsimilar locations in the Galaxy. In combining our results with other data in\nthe literature, we present evidence for large-scale (~kpc) azimuthal variations\nin abundances at Galacto-centric distances of 3-5kpc. While we cannot rule-out\nthat this observed behaviour is due to systematic offsets between different\nmeasurement techniques, we do find evidence for similar behaviour in a study of\nthe barred-spiral galaxy NGC4736 which uses homogeneous methodology. We suggest\nthat these azimuthal abundance variations could result from the intense but\npatchy star formation driven by the potential of the central bar.", "positive": "A wind-based unification model for NGC 5548: spectral holidays, non-disk\n emission, and implications for changing-look quasars: The 180-day Space Telescope and Optical Reverberation Mapping campaign on NGC\n5548 discovered an anomalous period, the broad-line region (BLR) holiday, in\nwhich the emission lines decorrelated from the continuum variations. This is\nimportant since the correlation between the continuum-flux variations and the\nemission-line response is the basic assumption for black hole (BH) mass\ndeterminations through reverberation mapping. During the BLR holiday, the\nhigh-ionization intrinsic absorption lines also decorrelated from the continuum\nas a result of variable covering factor of the line of sight (LOS) obscurer.\nThe emission lines are not confined to the LOS, so this does not explain the\nBLR holiday. If the LOS obscurer is a disk wind, its streamlines must extend\ndown to the plane of the disk and the base of the wind would lie between the BH\nand the BLR, forming an equatorial obscurer. This obscurer can be transparent\nto ionizing radiation, or can be translucent, blocking only parts of the SED,\ndepending on its density. An emission-line holiday is produced if the wind\ndensity increases only slightly above its transparent state. Both obscurers are\nparts of the same wind, so they can have associated behavior in a way that\nexplains both holidays. A very dense wind would block nearly all ionizing\nradiation, producing a Seyfert 2 and possibly providing a contributor to the\nchanging-look AGN phenomenon. Disk winds are very common and we propose that\nthe equatorial obscurers are too, but mostly in a transparent state." }, { "anchor": "Herschel Far-IR counterparts of SDSS galaxies: Analysis of commonly used\n Star Formation Rate estimates: We study a hundred of galaxies from the spectroscopic Sloan Digital Sky\nSurvey with individual detections in the Far-Infrared Herschel PACS bands (100\nor 160 $\\mu$m) and in the GALEX Far-UltraViolet band up to z$\\sim$0.4 in the\nCOSMOS and Lockman Hole fields. The galaxies are divided into 4 spectral and 4\nmorphological types. For the star forming and unclassifiable galaxies we\ncalculate dust extinctions from the UV slope, the H$\\alpha$/H$\\beta$ ratio and\nthe $L_{\\rm IR}/L_{\\rm UV}$ ratio. There is a tight correlation between the\ndust extinction and both $L_{\\rm IR}$ and metallicity. We calculate\nSFR$_{total}$ and compare it with other SFR estimates (H$\\alpha$, UV, SDSS)\nfinding a very good agreement between them with smaller dispersions than\ntypical SFR uncertainties. We study the effect of mass and metallicity, finding\nthat it is only significant at high masses for SFR$_{H\\alpha}$. For the AGN and\ncomposite galaxies we find a tight correlation between SFR and L$_{IR}$\n($\\sigma\\sim$0.29), while the dispersion in the SFR - L$_{UV}$ relation is\nlarger ($\\sigma\\sim$0.57). The galaxies follow the prescriptions of the\nFundamental Plane in the M-Z-SFR space.", "positive": "High Equivalent Width of H\u03b1+[N II] Emission in z~8 Lyman-break\n Galaxies from IRAC 5.8\u03bcm Observations: Evidence for Efficient\n Lyman-continuum Photon production in the Epoch of Re-ionization: We measure, for the first time, the median equivalent width (EW) of\nH$\\alpha$+[N II] in star-forming galaxies at $z\\sim8$. Our estimate leverages\nthe unique photometric depth of the Spitzer/IRAC $5.8\\mu$m-band mosaics\n(probing $\\approx 5500 - 7100$ A at $z\\sim8$) of the GOODS Reionization Era\nWide Area Treasury from Spitzer (GREATS) program. We median stacked the stamps\nof $102$ Lyman-break galaxies in the $3.6, 4.5, 5.8$ and $8.0\\mu$m bands, after\ncarefully removing potential contamination from neighbouring sources. We infer\nan extreme rest-frame EW$_0$(H$\\alpha$+[N II])$=2328^{+1326}_{-1127}$ A from\nthe measured red $[3.6]-[5.8]=0.82\\pm0.27$ mag, consistent with young\n($\\lesssim10^7$ yr) average stellar population ages at $z\\sim8$. This implies\nan ionizing photon production efficiency of\n$\\log(\\xi_{\\mathrm{ion},0}/\\mathrm{erg\\ Hz}^{-1})=25.97^{+0.18}_{-0.28}$. Such\na high value for photo production, similar to the highest values found at\n$z\\lesssim4$, indicates that only modest escape fractions\n$f_\\mathrm{esc}\\lesssim0.3$ (at $2\\sigma$) are sufficient for galaxies brighter\nthan $M_\\mathrm{UV}<-18$ mag to re-ionize the neutral Hydrogen at $z\\sim8$.\nThis requirement is relaxed even more to $f_\\mathrm{esc}\\le 0.1$ when\nconsidering galaxies brighter than $M_\\mathrm{UV}\\approx -13$ mag, consistent\nwith recent luminosity functions and as typically assumed in studies addressing\nre-ionization. These exceptional results clearly indicate that galaxies can be\nthe dominant source of reionizing photons, and provide us with an exciting\nglimpse into what we might soon learn about the early universe, and\nparticularly about the Reionization Epoch, from forthcoming JWST/MIRI and\nNIRCam programs." }, { "anchor": "The Dynamics of Charged Dust in Magnetized Molecular Clouds: We study the dynamics of large, charged dust grains in turbulent giant\nmolecular clouds (GMCs). Massive dust grains behave as aerodynamic particles in\nprimarily neutral dense gas, and thus are able to produce dramatic small-scale\nfluctuations in the dust-to-gas ratio. Hopkins & Lee (2016) directly simulated\nthe dynamics of neutral dust grains in super-sonic MHD turbulence, typical of\nGMCs, and showed that the dust-to-gas fluctuations can exceed factor ~1000 on\nsmall scales, with important implications for star formation, stellar\nabundances, and dust behavior and growth. However, even in primarily neutral\ngas in GMCs, dust grains are negatively charged and Lorentz forces are\nnon-negligible. Therefore, we extend our previous study by including the\neffects of Lorentz forces on charged grains (in addition to drag). For small\ncharged grains (sizes <0.1 micron), Lorentz forces suppress dust-to-gas ratio\nfluctuations, while for large grains (sizes >1 micron), Lorentz forces have\nessentially no effect, trends that are well explained with a simple theory of\ndust magnetization. In some special intermediate cases, Lorentz forces can\nenhance dust-gas segregation. Regardless, for the physically expected scaling\nof dust charge with grain size, we find the most important effects depend on\ngrain size (via the drag equation) with Lorentz forces/charge as a second-order\ncorrection. We show that the dynamics we consider are determined by three\ndimensionless numbers in the limit of weak background magnetic fields: the\nturbulent Mach number, a dust drag parameter (proportional to grain size) and a\ndust Lorentz parameter (proportional to grain charge); these allow us to\ngeneralize our simulations to a wide range of conditions.", "positive": "Detecting Detached Black Hole binaries through Photometric Variability: Understanding the connection between the properties of black holes (BHs) and\ntheir progenitors is interesting in many branches of astrophysics. Discovering\nBHs in detached orbits with luminous companions (LCs) promises to help create\nthis map since the LC and BH progenitor are expected to have the same\nmetallicity and formation time. We explore the possibility of detecting BH-LC\nbinaries in detached orbits using photometric variations of the LC flux,\ninduced by tidal ellipsoidal variation, relativistic beaming, and self-lensing.\nWe create realistic present-day populations of detached BH-LC binaries in the\nMilky Way (MW) using binary population synthesis where we adopt observationally\nmotivated initial stellar and binary properties, star formation history and\npresent-day distribution of these sources in the MW based on detailed\ncosmological simulations. We test detectability of these sources via\nphotometric variability by Gaia and TESS missions by incorporating their\nrespective detailed detection biases as well as interstellar extinction. We\nfind that Gaia (TESS) is expected to resolve ~700-1500 (~100-400) detached\nBH-LC binaries depending on the photometric precision and details of supernova\nphysics. We find that ~369 BH-LC binaries would be common both in Gaia and\nTESS. Moreover, between ~80-270 (~70-290) of these BH-LC binaries can be\nfurther characterised using Gaia's radial velocity (astrometry) measurements." }, { "anchor": "Flattened velocity dispersion profiles in Globular Clusters: Newtonian\n tides or modified gravity?: Over the past couple of years, a number of observational studies have\nconfirmed the flattening of the radial velocity dispersion profiles for stars\nin various nearby globular clusters. As the projected radial coordinate is\nincreased, a radius appears beyond which, the measured velocity dispersion\nceases to drop and settles at a fixed value, $\\sigma_{\\infty}$. Under Newtonian\ngravity, this is explained by invoking tidal heating from the overall Milky Way\npotential on the outer, more loosely bound stars, of the globular clusters in\nquestion. From the point of view of modified gravity theories, such an outer\nflattening is expected on crossing the critical acceleration threshold $a_{0}$,\nbeyond which, a transition to MONDian dynamics is expected, were equilibrium\nvelocities cease to be a function of distance. In this paper we attempt to sort\nout between the above competing explanations, by looking at their plausibility\nin terms of an strictly empirical approach. We determine Newtonian tidal radii\nusing masses accurately calculated through stellar population modelling, and\nhence independent of any dynamical assumptions, distances, size and orbital\ndeterminations for a sample of 16 globular clusters. We show that their\nNewtonian tidal radii at perigalacticon are generally larger that the radii at\nwhich the flattening in the velocity dispersion profiles occurs, by large\nfactors of 4, on average. While this point makes the Newtonian tidal\nexplanation suspect, it is found that the radii at which the flattening is\nobserved on average correlate with the radii where the $a_{0}$ threshold is\ncrossed, and that $\\sigma_{\\infty}$ values scale with the fourth root of the\ntotal masses, all features predicted under modified gravity theories.", "positive": "The Mass-Metallicity Relation of Dwarf Galaxies at Cosmic Noon from JWST\n Observations: We present a study of the mass-metallicity relation (MZR) of 51 dwarf\ngalaxies ($M_\\star\\approx 10^{6.5} - 10^{9.5}~M_\\odot$) at $z = 2-3$ from the\nAbell 2744 and SMACS J0723-3732 galaxy cluster fields. These dwarf galaxies are\nidentified and confirmed by deep JWST/NIRISS imaging and slitless grism\nspectroscopic observations. By taking advantage of the superior performance of\nJWST and the gravitational lensing effect, we extend the previous MZR relation\nat $z=2-3$ to a much lower mass regime down by $\\approx$ 2.5 orders of\nmagnitude as compared with previous studies. We find that the MZR has a\nshallower slope at the low-mass end ($M_\\star<10^{9}~M_\\odot$), with a slope\nturnover point of $\\approx$ $10^9~M_\\odot$. This implies that the dominating\nfeedback processes in dwarf galaxies may be different from that in massive\ngalaxies. From $z=3$ to $z=2$, the metallicity of the dwarf galaxies is\nenhanced by $\\approx0.09$ dex for a given stellar mass, consistent with the\nmild evolution found in galaxies with higher mass. Furthermore, we confirm the\nexistence of a fundamental metallicity relation (FMR) between the gas-phase\nmetallicity, stellar mass, and star formation rate in dwarf galaxies at\n$z=2-3$. Our derived FMR, which has no significant redshift evolution, can be\nused as a benchmark to understand the origin of the anti-correlation between\nthe SFR and metallicity of dwarf galaxies in the high-$z$ Universe." }, { "anchor": "The SPLASH Survey: A Spectroscopic Analysis of the Metal-Poor,\n Low-Luminosity M31 dSph Satellite Andromeda X: Andromeda X (And X) is a newly discovered low-luminosity M31 dwarf spheroidal\ngalaxy (dSph) found by Zucker et al. (2007) in the Sloan Digital Sky Survey\n(SDSS - York et al. 2000). In this paper, we present the first spectroscopic\nstudy of individual red giant branch stars in And X, as a part of the SPLASH\nSurvey (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo).\nUsing the Keck II telescope and multiobject DEIMOS spectrograph, we target two\nspectroscopic masks over the face of the galaxy and measure radial velocities\nfor ~100 stars with a median accuracy of sigma_v ~ 3 km/s. The velocity\nhistogram for this field confirms three populations of stars along the sight\nline: foreground Milky Way dwarfs at small negative velocities, M31 halo red\ngiants over a broad range of velocities, and a very cold velocity ``spike''\nconsisting of 22 stars belonging to And X with v_rad = -163.8 +/- 1.2 km/s. By\ncarefully considering both the random and systematic velocity errors of these\nstars (e.g., through duplicate star measurements), we derive an intrinsic\nvelocity dispersion of just sigma_v = 3.9 +/- 1.2 km/s for And X, which for its\nsize, implies a minimum mass-to-light ratio of M/L =37^{+26}_{-19} assuming the\nmass traces the light. Based on the clean sample of member stars, we measure\nthe median metallicity of And X to be [Fe/H] = -1.93 +/- 0.11, with a slight\nradial metallicity gradient. The dispersion in metallicity is large,\nsigma([Fe/H]) = 0.48, possibly hinting that the galaxy retained much of its\nchemical enrichment products. We discuss the potential for better understanding\nthe formation and evolution mechanisms for M31's system of dSphs through\n(current) kinematic and chemical abundance studies, especially in relation to\nthe Milky Way sample. (abridged version)", "positive": "Metal Transport and Chemical Heterogeneity in Early Star Forming Systems: To constrain the properties of the first stars with the chemical abundance\npatterns observed in metal-poor stars, one must identify any non-trivial\neffects that the hydrodynamics of metal dispersal can imprint on the\nabundances. We use realistic cosmological hydrodynamic simulations to quantify\nthe distribution of metals resulting from one Population III supernova and from\na small number of such supernovae exploding in close succession. Overall,\nsupernova ejecta are highly inhomogeneously dispersed throughout the\nsimulations. When the supernova bubbles collapse, quasi-virialized\nmetal-enriched clouds, fed by fallback from the bubbles and by streaming of\nmetal-free gas from the cosmic web, grow in the centers of the dark matter\nhalos. Partial turbulent homogenization on scales resolved in the simulation is\nobserved only in the densest clouds where the vortical time scales are short\nenough to ensure true homogenization on subgrid scales. However, the abundances\nin the clouds differ from the gross yields of the supernovae. Continuing the\nsimulations until the cloud have gone into gravitational collapse, we predict\nthat the abundances in second-generation stars will be deficient in the\ninnermost mass shells of the supernova (if only one has exploded) or in the\nejecta of the latest supernovae (when multiple have exploded). This indicates\nthat hydrodynamics gives rise to biases complicating the identification of\nnucleosynthetic sources in the chemical abundance spaces of the surviving\nstars." }, { "anchor": "Using H$\u03b1$ Filaments to Probe AGN Feedback in Galaxy Clusters: Recent observations of giant ellipticals and brightest cluster galaxies\n(BCGs) provide tentative evidence for a correlation between the luminosity of\nthe H$\\alpha$ emitting gas filaments and the strength of feedback associated\nwith the active galactic nucleus (AGN). Motivated by this, we use 3D\nradiation-hydrodynamic simulations with the code Enzo to examine and quantify\nthe relationship between the observable properties of the H$\\alpha$ filaments\nand the kinetic and radiative feedback from supermassive black holes in BCGs.\nWe find that the spatial extent and total mass of the filaments show positive\ncorrelations with AGN feedback power and can therefore be used as probes of the\nAGN activity. We also examine the relationship between the AGN feedback power\nand velocity dispersion of the H$\\alpha$ filaments and find that the kinetic\nluminosity shows statistically significant correlation with the component of\nthe velocity dispersion along the jet axis but not the components perpendicular\nto it.", "positive": "A resolved analysis of cold dust and gas in the nearby edge-on spiral\n NGC 891: We investigate the connection between dust and gas in the nearby edge-on\nspiral galaxy NGC 891. High resolution Herschel PACS and SPIRE 70, 100, 160,\n250, 350, and 500 $\\mu$m images are combined with JCMT SCUBA 850 $\\mu$m\nobservations to trace the far-infrared/submillimetre spectral energy\ndistribution (SED). Maps of the HI 21 cm line and CO(J=3-2) emission trace the\natomic and molecular hydrogen gas, respectively. We fit one-component modified\nblackbody models to the integrated SED, finding a global dust mass of\n8.5$\\times$10$^{7}$ M$_{\\odot}$ and an average temperature of 23$\\pm$2 K. We\nalso fit the pixel-by-pixel SEDs to produce maps of the dust mass and\ntemperature. The dust mass distribution correlates with the total stellar\npopulation as traced by the 3.6 $\\mu$m emission. The derived dust temperature,\nwhich ranges from approximately 17 to 24 K, is found to correlate with the 24\n$\\mu$m emission. Allowing the dust emissivity index to vary, we find an average\nvalue of $\\beta$ = 1.9$\\pm$0.3. We confirm an inverse relation between the dust\nemissivity spectral index and dust temperature, but do not observe any\nvariation of this relationship with vertical height from the mid-plane of the\ndisk. A comparison of the dust properties with the gaseous components of the\nISM reveals strong spatial correlations between the surface mass densities of\ndust and the molecular hydrogen and total gas surface densities. Observed\nasymmetries in the dust temperature, and the H$_{2}$-to-dust and total\ngas-to-dust ratios hint that an enhancement in the star formation rate may be\nthe result of larger quantities of molecular gas available to fuel star\nformation in the NE compared to the SW. Whilst the asymmetry likely arises from\ndust obscuration due to the geometry of the line-of-sight projection of the\nspiral arms, we cannot exclude an enhancement in the star formation rate in the\nNE side of the disk." }, { "anchor": "Exploring the origin of thick disks using the NewHorizon and Galactica\n simulations: Ever since a thick disk was proposed to explain the vertical distribution of\nthe Milky Way disk stars, its origin has been a recurrent question. We aim to\nanswer this question by inspecting 19 disk galaxies with stellar mass greater\nthan $10^{10}\\,\\rm M_\\odot$ in recent cosmological high-resolution zoom-in\nsimulations: Galactica and NewHorizon. The thin and thick disks are reasonably\nreproduced by the simulations with scale heights and luminosity ratios as\nobserved. We then spatially classify the thin and thick disks and find that the\nthick disk stars are older, metal-poorer, kinematically-hotter, and higher in\naccreted star fraction, while both disks are dominated by the stars formed in\nsitu. Half of the in-situ stars in the thick disks are formed before the\ngalaxies develop their disks, and the rest are formed in spatially and\nkinematically thinner disks and then thickened with time by heating. However,\nthe 19 galaxies have various properties and evolutionary routes, highlighting\nthe need for statistically-large samples to draw general conclusions. We\nconclude from our simulations that the thin and thick disk components are not\nentirely distinct in terms of formation processes, but rather markers of the\nevolution of galactic disks. Moreover, as the combined result of the thickening\nof the existing disk stars and the continued formation of young thin-disk\nstars, the vertical distribution of stars does not change much after the disks\nsettle, pointing to the modulation of both orbital diffusion and star formation\nby the same confounding factor: the proximity of galaxies to marginal\nstability.", "positive": "The Nature of 500 Micron Risers II: Sub-mm Faint Dusty Star Forming\n Galaxies: We present SCUBA-2 and SMA follow-up observations of four candidate high\nredshift Dusty Star-Forming Galaxies, selected as sources with rising SEDs in\nthe 250, 350 and 500$\\mu$m Herschel SPIRE bands. Previous SMA observations\nshowed no counterparts to these sources, but in our deeper sub-mm observations\nwe detect counterparts to all four 500$\\mu$m risers, with three resolving into\nmultiple systems. For these three multiple systems, the SMA 345GHz ($\\approx\n870\\mu$m) observations recover $123 \\pm 73\\%$, $60 \\pm 15\\%$ and $19 \\pm 4\\%$\nrespectively of the integrated 850$\\mu$m flux density from SCUBA-2, indicating\nthat there may be additional sources below our SMA detection limit making up a\ndense, protocluster core. The fourth 500$\\mu$m riser was observed at a lower\nfrequency and so we cannot make a similar comparison. We estimate photometric\nredshifts based on FIR/sub-mm colours, finding that 3/4 likely lie at $z \\geq\n2$. This fits with the interpretation that the 500$\\mu$m riser selection\ncriterion selects both intrinsically red, individual galaxies at $z > 4$, and\nmultiple systems at more moderate redshifts, artificially reddened by the\neffects of blending. We use the SCUBA-2 850$\\mu$m maps to investigate the\nenvironments of these 500$\\mu$m risers. By constructing cumulative number\ncounts and estimating photometric redshifts for surrounding SCUBA-2 detections,\nwe find that one of our 500$\\mu$m risers could plausibly reside in a $z \\geq 2$\nprotocluster. We infer that bright 500$\\mu$m risers with faint 850$\\mu$m flux\ndensities are typically multiple systems at $z \\geq 2$ that may reside in\noverdensities of bright sub-mm galaxies." }, { "anchor": "A self-consistent stellar and 3D nebular model for Planetary Nebula\n IC418: We present a coherent stellar and nebular model reproducing the observations\nof the Planetary Nebula IC418. We want to test whether a stellar model obtained\nby fitting the stellar observations is able to satisfactory ionize the nebula\nand reproduce the nebular observations, which is by no mean evident. This\nallows us to determine all the physical parameters of both the star and the\nnebula, including the abundances and the distance. We used all the\nobservational material available (FUSE, IUE, STIS and optical spectra) to\nconstrain the stellar atmosphere model performed using the CMFGEN code. The\nphotoionization model is done with Cloudy_3D, and is based on CTIO, Lick, SPM,\nIUE and ISO spectra as well as HST images. More than 140 nebular emission lines\nare compared to the observed intensities. We reproduce all the observations for\nthe star and the nebula. The 3D morphology of the gas distribution is\ndetermined. The effective temperature of the star is 36.7kK. Its luminosity is\n7700 solar luminosity. We describe an original method to determine the distance\nof the nebula using evolutionary tracks. No clumping factor is need to\nreproduce the age-luminosity relation. The distance of 1.25 kpc is found in\nvery good agreement with recent determination using parallax method. The\nchemical composition of both the star and the nebula are determined. Both are\nCarbon-rich. The nebula presents evidence of depletion of elements Mg, Si, S,\nCl (0.5 dex lower than solar) and Fe (2.9 dex lower than solar). This is the\nfirst self-consistent stellar and nebular model for a Planetary Nebula that\nreproduces all the available observations ranging from IR to UV, showing that\nthe combined approach for the modeling process leads to more restrictive\nconstraints and, in principle, more trustworthy results.", "positive": "Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions\n in four star-forming regions in the Large Magellanic Cloud: The aim of our study is to investigate the physical properties of the\nstar-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by\nseparating the origin of the emission lines spatially and spectrally. Following\nOkada et al. (2015, Paper I), we investigate different phases of the ISM traced\nby carbon-bearing species in four star-forming regions in the LMC, and model\nthe physical properties using the KOSMA-tau PDR model. We mapped 3--13\narcmin$^2$ areas in 30 Dor, N158, N160 and N159 along the molecular ridge of\nthe LMC in [CII]158um with GREAT on board SOFIA, and in CO(2-1) to (6-5),\n$^{13}$CO(2-1) and (3-2), [CI]3P1-3P0 and 3P2-3P1 with APEX. In all four\nstar-forming regions, the line profiles of CO, $^{13}$CO, and [CI] emission are\nsimilar, whereas [CII] typically shows wider line profiles or an additional\nvelocity component. For selected positions in N159 and 30 Dor, we observed the\nvelocity-resolved [OI] 145um and 63um lines for the first time with upGREAT. At\nsome positions, the [OI] line profiles match those of CO, at other positions\nthey are more similar to the [CII] profiles. We interpret the different line\nprofiles of CO, [CII] and [OI] as contributions from spatially separated clouds\nand/or clouds in different physical phases, which give different line ratios\ndepending on their physical properties. We model the emission from the CO,\n[CI], [CII], and [OI] lines and the far-infrared continuum emission using the\nlatest KOSMA-tau PDR model, which treats the dust-related physics consistently\nand computes the dust continuum SED together with the line emission of the\nchemical species. We find that the line and continuum emissions are not\nwell-reproduced by a single clump ensemble. Toward the CO peak at N159~W, we\npropose a scenario that the CO, [CII], and [OI] 63um emission are weaker than\nexpected because of mutual shielding among clumps. (abridged for arXiv)" }, { "anchor": "Constraints on the Intracluster Dust Emission in the Coma Cluster of\n Galaxies: We have undertaken a search for the infrared emission from the intracluster\ndust in the Coma cluster of galaxies by the Multiband Imaging Photometer for\nSpitzer. Our observations yield the deepest mid and far-infrared images of a\ngalaxy cluster ever achieved. In each of the three bands, we have not detected\na signature of the central excess component in contrast to the previous report\non the detection by Infrared Space Observatory (ISO). We still find that the\nbrightness ratio between 70 and 160 microns shows a marginal sign of the\ncentral excess, in qualitative agreement with the ISO result. Our analysis\nsuggests that the excess ratio is more likely due to faint infrared sources\nlying on fluctuating cirrus foreground. Our observations yield the 2 sigma\nupper limits on the excess emission within 100 kpc of the cluster center as 5 x\n10^-3 MJy/sr, 6 x 10^-2 MJy/sr, and 7 x 10^-2 MJy/sr, at 24, 70, and 160\nmicrons, respectively. These values are in agreement with those found in other\ngalaxy clusters and suggest that dust is deficient near the cluster center by\nmore than 3 orders of magnitude compared to the interstellar medium.", "positive": "The rate and contribution of mergers to mass assembly from NIRCam\n observations of galaxy candidates up to 13.3 billion years ago: We present an analysis of the galaxy merger rate in the redshift range\n$4.0 10^11.4 MSun) discs form primarily via minor mergers\nbetween spheroids and gas-rich satellites, which create new rotational stellar\ncomponents and leave discs as remnants. Here, we use UV-optical and HI data of\nmassive galaxies, from the SDSS, GALEX, DECaLS and ALFALFA surveys, to test\nthese theoretical predictions. Observed massive discs account for ~13% of\nmassive galaxies, in good agreement with theory (~11%). ~64% of the observed\nmassive discs exhibit tidal features, which are likely to indicate recent minor\nmergers, in the deep DECaLS images (compared to ~60% in their simulated\ncounterparts). The incidence of these features is at least four times higher\nthan in low-mass discs, suggesting that, as predicted, minor mergers play a\nsignificant (and outsized) role in the formation of these systems. The\nempirical star-formation rates agree well with theoretical predictions and, for\na small galaxy sample with HI detections, the HI masses and fractions are\nconsistent with the range predicted by the simulation. The good agreement\nbetween theory and observations indicates that extremely massive discs are\nindeed remnants of recent minor mergers between spheroids and gas-rich\nsatellites." }, { "anchor": "The Proper Motion of PSR J0205+6449 in 3C 58: We report on sensitive phase-referenced and gated 1.4-GHz VLBI radio\nobservations of the pulsar PSR J0205+6449 in the young pulsar-wind nebula 3C\n58, made in 2007 and 2010. We employed a novel technique where the ~105-m Green\nBank telescope is used simultaneously to obtain single-dish data used to\ndetermine the pulsar's period as well as to obtain the VLBI data, allowing the\nVLBI correlation to be gated synchronously with the pulse to increase the\nsignal-to-noise. The high timing noise of this young pulsar precludes the\ndetermination of the proper motion from the pulsar timing. We derive the\nposition of the pulsar accurate at the milliarcsecond level, which is\nconsistent with a re-determined position from the Chandra X-ray observations.\nWe reject the original tentative optical identification of the pulsar by\nShearer and Neustroev (2008), but rather identify a different optical\ncounterpart on their images, with R-band magnitude ~24. We also determine an\naccurate proper motion for PSR J0205+6449 of (2.3 +- 0.3) mas/yr, corresponding\nto a projected velocity of only (35 +- 6) km/s for a distance of 3.2 kpc, at\np.a. -38 deg. This projected velocity is quite low compared to the velocity\ndispersion of known pulsars of ~200 km/s. Our measured proper motion does not\nsuggest any particular kinematic age for the pulsar.", "positive": "On the dichotomy of Seyfert 2 galaxies: intrinsic differences and\n evolution: We present a study of the local environment (<200 kpc/h) of 31 Hidden Broad\nLine Region (HBLR) and 43 non-HBLR Seyfert 2 galaxies (Sy2) in the nearby\nuniverse (z<0.04). To compare our findings, we constructed two control samples\nthat match the redshift and the morphological type distribution of the HBLR and\nnon-HBLR samples respectively. We used the NED (NASA extragalactic database) to\nfind all neighboring galaxies within projected radius of 200 kpc/h around each\ngalaxy, and radial velocity difference delta_u< 500 km/s. We find that, within\na projected radius of at least 150 kpc/h around each Seyfert, the fraction of\nnon-HBLR Sy2 galaxies with a close companion is significantly higher than that\nof their control sample, at the 96% confidence level. Interestingly, the\ndifference is due to the high frequency of mergers in the non-HBLR sample,\nseven versus only one in the control sample, while also they present a high\nnumber of hosts with signs of peculiar morphology. In sharp contrast, the HBLR\nsample is consistent with its control sample and furthermore, the number of\ntheir host galaxies that present peculiar morphology, which probably implies\nsome level of interactions or merging in the past, is the lowest in all four\ngalaxy samples. Given that the HBLR Seyfert 2 galaxies are essentially Seyfert\n1 (Sy1), with their broad line region (BLR) hidden because of the obscuration\nby the torus, while the non-HBLR Sy2 sample probably also includes\nintrinsically different objects, like \"true\" Sy2s that lack the BLR, and\nheavily obscured objects that prohibit even its indirect detection, our results\nare discussed within the context of an evolutionary sequence of activity\ntriggered by close galaxy interactions and merging. We argue that the non-HBLR\nSy2 galaxies may represent different stages of this sequence, possibly the\nbeginning and the end of the nuclear activity." }, { "anchor": "Corrugated velocity patterns in the spiral galaxies: NGC 278, NGC 1058,\n NGC 2500 \\& UGC 3574: We address the study of the \\Ha\\ vertical velocity field in a sample of four\nnearly face-on galaxies using long slit spectroscopy taken with the ISIS\nspectrograph attached to the WHT at the Roque de los Muchachos Observatory\n(Spain). The spatial structure of the velocity vertical component shows a\nradial corrugated pattern with spatial scales higher or within the order of {\none} kiloparsec. The gas is mainly ionized by high-energy photons: only in some\nlocations of NGC~278 and NGC~1058 is there some evidence of ionization by\nlow-velocity shocks, which, in the case of NGC~278, could be due to minor\nmergers. The behaviour of the gas in the neighbourhood of the spiral arms fits,\nin the majority of the observed cases, with that predicted by the so-called\nhydraulic bore mechanism, where a thick magnetized disk encounters a spiral\ndensity perturbation. The results obtained show that it is { difficult to\nexplain the \\Ha\\ large scale velocity field without the presence of a\nmagnetized, thick galactic disk}. Larger samples and spatial covering of the\ngalaxy disks are needed to provide further insight into this problem.", "positive": "Terzan 5: a pristine fragment of the Galactic Bulge?: Terzan 5 is a stellar system located in the inner Bulge of the Galaxy and has\nbeen historically catalogued as a globular cluster. However, recent photometric\n(Ferraro et al. 2009) and spectroscopic (Origlia et al. 2011; Origlia et al.\n2013) investigations have shown that it hosts at least three stellar\npopulations with different iron abundances (with a total spread of\nDelta[Fe/H]>1 dex) thus demonstrating that Terzan 5 is not a genuine globular\ncluster. In addition, the striking similarity between the chemical patterns of\nthis system and those of its surrounding environment, the Galactic Bulge, from\nthe point of view of both the metallicity distribution and the alpha-element\nenrichment, suggests that Terzan 5 could be a pristine fragment of the Bulge\nitself." }, { "anchor": "The Panchromatic Hubble Andromeda Treasury XI: The Spatially-Resolved\n Recent Star Formation History of M31: We measure the recent star formation history (SFH) across M31 using optical\nimages taken with the \\texit{Hubble Space Telescope} as part of the\nPanchromatic Hubble Andromeda Treasury (PHAT). We fit the color-magnitude\ndiagrams in ~9000 regions that are ~100 pc $\\times$ 100 pc in projected size,\ncovering a 0.5 square degree area (~380 kpc$^2$, deprojected) in the NE\nquadrant of M31. We show that the SFHs vary significantly on these small\nspatial scales but that there are also coherent galaxy-wide fluctuations in the\nSFH back to ~500 Myr, most notably in M31's 10-kpc star-forming ring. We find\nthat the 10-kpc ring is at least 400 Myr old, showing ongoing star formation\nover the past ~500 Myr. This indicates the presence of molecular gas in the\nring over at least 2 dynamical times at this radius. We also find that the\nring's position is constant throughout this time, and is stationary at the\nlevel of 1 km/s, although there is evidence for broadening of the ring due to\ndiffusion of stars into the disk. Based on existing models of M31's ring\nfeatures, the lack of evolution in the ring's position makes a purely\ncollisional ring origin highly unlikely. We find that the global SFR has been\nfairly constant over the last ~500 Myr, though it does show a small increase at\n50 Myr that is 1.3 times the average SFR over the past 100 Myr. During the last\n~500 Myr, ~60% of all SF occurs in the 10-kpc ring. Finally, we find that in\nthe past 100 Myr, the average SFR over the PHAT survey area is $0.28\\pm0.03$\nM$_\\odot$ yr$^{-1}$ with an average deprojected intensity of $7.3 \\times\n10^{-4}$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$, which yields a total SFR of ~0.7\nM$_\\odot$ yr$^{-1}$ when extrapolated to the entire area of M31's disk. This\nSFR is consistent with measurements from broadband estimates. [abridged]", "positive": "A comparison of the local spiral structure from Gaia DR2 and VLBI maser\n parallaxes: Context. The Gaia mission has released the second data set (Gaia DR2), which\ncontains parallaxes and proper motions for a large number of massive, young\nstars. Aims. We investigate the spiral structure in the solar neighborhood\nrevealed by Gaia DR2 and compare it with that depicted by VLBI maser\nparallaxes. Methods. We examined three samples with different constraints on\nparallax uncertainty and distance errors and stellar spectral types: (1) all OB\nstars with parallax errors of less than 10%; (2) only O-type stars with 0.1 mas\nerrors imposed and with parallax distance errors of less than 0.2 kpc; and (3)\nonly O-type stars with 0.05 mas errors imposed and with parallax distance\nerrors of less than 0.3 kpc. Results. In spite of the significant distance\nuncertainties for stars in DR2 beyond 1.4 kpc, the spiral structure in the\nsolar neighborhood demonstrated by Gaia agrees well with that illustrated by\nVLBI maser results. The O-type stars available from DR2 extend the spiral arm\nmodels determined from VLBI maser parallaxes into the fourth Galactic quadrant,\nand suggest the existence of a new spur between the Local and Sagittarius arms." }, { "anchor": "Blue Rest-Frame UV-Optical Colors in z~8 Galaxies from GREATS: Very\n Young Stellar Populations at ~650 Myr of Cosmic Time: Deep rest-optical observations are required to accurately constrain the\nstellar populations of $z\\sim8$ galaxies. Due to significant limitations in the\navailability of such data for statistically complete samples, observational\nresults have been limited to modest numbers of bright or lensed sources. To\nrevolutionize the present characterization of $z\\sim8$ galaxies, we exploit the\nultradeep ($\\sim27$ mag, $3\\sigma$) Spitzer/IRAC $3.6\\mu$m and $4.5\\mu$m data,\nprobing the rest-frame optical at $z\\sim8$, over $\\sim200$ arcmin$^2$ of the\nGOODS fields from the recently completed GOODS Re-ionization Era wide-Area\nTreasury from Spitzer (GREATS) program, combined with observations in the\nCANDELS UDS and COSMOS fields. We stacked $\\gtrsim100$ $z\\sim8$ Lyman-Break\ngalaxies in four bins of UV luminosity ($M_\\mathrm{UV}\\sim -20.7$ to $-18.4$)\nand study their $H_\\mathrm{160}-[3.6]$ and $[3.6]-[4.5]$ colors. We find young\nages ($\\lesssim100$ Myr) for the three faintest stacks, inferred from their\nblue $H_\\mathrm{160}-[3.6]\\sim 0$ mag colors, consistent with a negative Balmer\nbreak. Meanwhile, the redder $H_\\mathrm{160}-[3.6]$ color seen in the brightest\nstack is suggestive of slightly older ages. We explored the existence of a\ncorrelation between the UV luminosity and age, and find either no trend or\nfainter galaxies being younger. The stacked SEDs also exhibit very red\n$[3.6]-[4.5]\\sim0.5$ mag colors, indicative of intense [OIII]+H$\\beta$ nebular\nemission and SFR. The correspondingly high specific star-formation rates,\nsSFR$\\gtrsim10$Gyr$^{-1}$, are consistent with recent determinations at similar\nredshifts and higher luminosities, and support the co-evolution between the\nsSFR and the specific halo mass accretion rate.", "positive": "A Multi-Resolution Method for Modelling Galaxy and Massive Black Hole\n Mergers: The coalescence of the most massive black hole (MBH) binaries releases\ngravitational waves (GWs) within the detectable frequency range of Pulsar\nTiming Arrays (PTAs) $(10^{-9} - 10^{-6})$ Hz. The incoherent superposition of\nGWs from MBH mergers, the stochastic Gravitational Wave Background (GWB), can\nprovide unique information on MBH parameters and the large-scale structure of\nthe Universe. The recent evidence for a GWB reported by the PTAs opens an\nexciting new window onto MBHs and their host galaxies. However, the\nastrophysical interpretation of the GWB requires accurate estimations of MBH\nmerger timescales for a statistically representative sample of galaxy mergers.\nThis is numerically challenging; a high numerical resolution is required to\navoid spurious relaxation and stochastic effects whilst a large number of\nsimulations is needed to sample a cosmologically representative volume. Here,\nwe present a new multi-mass modelling method to increase the central resolution\nof a galaxy model at a fixed particle number. We follow mergers of galaxies\nhosting central MBHs with the Fast Multiple Method code Griffin at two\nreference resolutions and with two refinement schemes. We show that both\nrefinement schemes are effective at increasing central resolution, reducing\nspurious relaxation and stochastic effects. A particle number of $N\\geq 10^{6}$\nwithin a radius of 5 times the sphere of influence of the MBHs is required to\nreduce numerical scatter in the binary eccentricity and the coalescence\ntimescale to <30$\\%$; a resolution that can only be reached at present with the\nmass refinement scheme." }, { "anchor": "First Space-VLBI Observations of Sagittarius A*: We report results from the first Earth-space VLBI observations of the\nGalactic Center supermassive black hole, Sgr A*. These observations used the\nspace telescope Spektr-R of the RadioAstron project together with a global\nnetwork of 20 ground telescopes, observing at a wavelength of 1.35cm. Spektr-R\nprovided baselines up to 3.9 times the diameter of the Earth, corresponding to\nan angular resolution of approximately 55 microarcseconds and a spatial\nresolution of $5.5 R_{\\rm Sch}$ at the source, where $R_{\\rm Sch} \\equiv 2 G\nM/c^2$ is the Schwarzschild radius of Sgr A*. Our short ground baseline\nmeasurements (<80 M\\lambda) are consistent with an anisotropic Gaussian image,\nwhile our intermediate ground baseline measurements (100-250 M\\lambda) confirm\nthe presence of persistent image substructure in Sgr A*. Both features are\nconsistent with theoretical expectations for strong scattering in the ionized\ninterstellar medium, which produces Gaussian scatter-broadening on short\nbaselines and refractive substructure on long baselines. We do not detect\ninterferometric fringes on any of the longer ground baselines or on any\nground-space baselines. While space VLBI offers a promising pathway to sharper\nangular resolution and the measurement of key gravitational signatures in black\nholes, such as their photon rings, our results demonstrate that space VLBI\nstudies of Sgr A* will require sensitive observations at submillimeter\nwavelengths.", "positive": "High resolution observations of Cen A: Yellow and red supergiants in a\n region of jet-induced star formation?: We present the analysis of near infrared (NIR), adaptive optics (AO) Subaru\nand archived HST imaging data of a region near the northern middle lobe (NML)\nof the Centaurus A (Cen A) jet, at a distance of $\\sim15$ kpc north-east (NE)\nfrom the center of NGC5128. Low-pass filtering of the NIR images reveals strong\n-- $>3\\sigma$ above the background mean -- signal at the expected position of\nthe brightest star in the equivalent HST field. Statistical analysis of the NIR\nbackground noise suggests that the probability to observe $>3\\sigma$ signal at\nthe same position, in three independent measurements due to stochastic\nbackground fluctuations alone is negligible ($\\leq10^{-7}\\%$) and, therefore,\nthat this signal should reflect the detection of the NIR counterparts of the\nbrightest HST star. An extensive photometric analysis of this star yields\n$V-I$, visual-NIR, and NIR colors expected from a yellow supergiant (YSG) with\nan estimated age $\\sim10^{+4}_{-3}$ Myr. Furthermore, the second and third\nbrighter HST stars are, likely, also supergiants in Cen A, with estimated ages\n$\\sim16^{+6}_{-3}$ Myr and $\\sim25^{+15}_{-9}$ Myr, respectively. The ages of\nthese three supergiants are in good agreement with the ages of the young\nmassive stars that were previously found in the vicinity and are thought to\nhave formed during the later phases of the jet-HI cloud interaction that\nappears to drive the star formation (SF) in the region for the past $\\sim100$\nMyr." }, { "anchor": "A Self-interacting Dark Matter Solution to the Extreme Diversity of\n Low-mass Halo Properties: The properties of low-mass dark matter (DM) halos appear to be remarkably\ndiverse relative to cold, collisionless DM predictions, even in the presence of\nbaryons. We show that self-interacting DM (SIDM) can simultaneously explain\nobservations of halo diversity at two opposite extremes$-$the inner density\nprofile of the dense substructure perturbing the strong lens galaxy\nSDSSJ0946+1006 and the rotation curves of isolated, gas-rich ultradiffuse\ngalaxies (UDGs). To achieve this, we present the first cosmological zoom-in\nsimulation featuring strong DM self-interactions in a galaxy group environment\ncentered on a $10^{13}~M_{\\mathrm{\\odot}}$ host halo. In our SIDM simulation,\nmost surviving subhalos of the group-mass host are deeply core-collapsed,\nyielding excellent candidates for the observed dense strong-lens perturber.\nSelf-interactions simultaneously create kiloparsec-scale cores in\nlow-concentration isolated halos, which could host the observed UDGs. Our\nscenario can be further tested with observations of DM structure and galaxies\nover a wide mass range.", "positive": "Determining sub-parsec supermassive black hole binary orbits with\n infrared interferometry: Radial velocity monitoring has revealed the presence of moving broad emission\nlines in some quasars, potentially indicating the presence of a sub-parsec\nbinary system. Phase-referenced, near-infrared interferometric observations\ncould map out the binary orbit by measuring the photocenter difference between\na broad emission line and the hot dust continuum. We show that astrometric data\nover several years may be able to detect proper motions and accelerations,\nconfirming the presence of a binary and constraining system parameters. The\nbrightness, redshifts, and astrometric sizes of current candidates are well\nmatched to the capabilities of the upgraded VLTI/GRAVITY+ instrument, and we\nidentify a first sample of 10 possible candidates. The astrometric signature\ndepends on the morphology and evolution of hot dust emission in supermassive\nblack hole binary systems. Measurements of the photocenter offset may reveal\nbinary motion whether the hot dust emission region is fixed to the inner edge\nof the circumbinary disk, or moves in response to the changing irradiation\npattern from an accreting secondary black hole." }, { "anchor": "A finer view of the conditional galaxy luminosity function and\n magnitude-gap statistics: The gap between first and second ranked galaxy magnitudes in groups is often\nconsidered a tracer of their merger histories, which in turn may affect galaxy\nproperties, and also serves to test galaxy luminosity functions (LFs). We\nremeasure the conditional luminosity function (CLF) of the Main Galaxy Sample\nof the SDSS in an appropriately cleaned subsample of groups from the Yang\ncatalog. We find that, at low group masses, our best-fit CLF have steeper\nsatellite high ends, yet higher ratios of characteristic satellite to central\nluminosities in comparison with the CLF of Yang et al. (2008). The observed\nfractions of groups with large and small magnitude gaps as well as the Tremaine\n& Richstone (1977) statistics, are not compatible with either a single\nSchechter LF or with a Schechter-like satellite plus lognormal central LF.\nThese gap statistics, which naturally depend on the size of the subsamples, and\nalso on the maximum projected radius, $R_{\\rm max}$, for defining the 2nd\nbrightest galaxy, can only be reproduced with two-component CLFs if we allow\nsmall gap groups to preferentially have two central galaxies, as expected when\ngroups merge. Finally, we find that the trend of higher gap for higher group\nvelocity dispersion, $\\sigma_{\\rm v}$, at given richness, discovered by Hearin\net al. (2013), is strongly reduced when we consider $\\sigma_{\\rm v}$ in bins of\nrichness, and virtually disappears when we use group mass instead of\n$\\sigma_{\\rm v}$. This limits the applicability of gaps in refining\ncosmographic studies based on cluster counts.", "positive": "Application of a Neural Network classifier for the generation of clean\n Small Magellanic Cloud stellar samples: Context. Previous attempts to separate Small Magellanic Cloud (SMC) stars\nfrom the Milky Way (MW) foreground stars are based only on the proper motions\nof the stars. Aims. In this paper we develop a statistical classification\ntechnique to effectively separate the SMC stars from the MW stars using a wider\nset of Gaia data. We aim to reduce the possible contamination from MW stars\ncompared to previous strategies. Methods. The new strategy is based on neural\nnetwork classifier, applied to the bulk of the Gaia DR3 data. We produce three\nsamples of stars flagged as SMC members, with varying levels of completeness\nand purity, obtained by application of this classifier. Using different test\nsamples we validate these classification results and we compare them with the\nresults of the selection technique employed in the Gaia Collaboration papers,\nwhich was based solely on the proper motions. Results. The contamination of MW\nin each of the three SMC samples is estimated to be in the 10-40%; the \"best\ncase\" in this range is obtained for bright stars (G > 16), which belong to the\nVlos sub-samples, and the \"worst case\" for the full SMC sample determined by\nusing very stringent criteria based on StarHorse distances. A further check\nbased on the comparison with a nearby area with uniform sky density indicates\nthat the global contamination in our samples is probably close to the low end\nof the range, around 10%. Conclusions. We provide three selections of SMC star\nsamples with different degrees of purity and completeness, for which we\nestimate a low contamination level and have successfully validated using SMC RR\nLyrae, SMC Cepheids and SMC/MW StarHorse samples." }, { "anchor": "Evolution of galactic planes of satellites in the EAGLE simulation: We study the formation of planes of dwarf galaxies around Milky Way (MW)-mass\nhaloes in the EAGLE galaxy formation simulation. We focus on satellite systems\nsimilar to the one in the MW: spatially thin or with a large fraction of\nmembers orbiting in the same plane. To characterise the latter, we introduce a\nrobust method to identify the subsets of satellites that have the most\nco-planar orbits. Out of the 11 MW classical dwarf satellites, 8 have highly\nclustered orbital planes whose poles are contained within a $22^\\circ$ opening\nangle centred around $(l,b)=(182^\\circ,-2^\\circ)$. This configuration stands\nout when compared to both isotropic and typical $\\Lambda$CDM satellite\ndistributions. Purely flattened satellite systems are short-lived chance\nassociations and persist for less than $1~\\rm{Gyr}$. In contrast, satellite\nsubsets that share roughly the same orbital plane are longer lived, with half\nof the MW-like systems being at least $4~\\rm{Gyrs}$ old. On average, satellite\nsystems were flatter in the past, with a minimum in their minor-to-major axes\nratio about $9~\\rm{Gyrs}$ ago, which is the typical infall time of the\nclassical satellites. MW-like satellite distributions have on average always\nbeen flatter than the overall population of satellites in MW-mass haloes and,\nin particular, they correspond to systems with a high degree of anisotropic\naccretion of satellites. We also show that torques induced by the aspherical\nmass distribution of the host halo channel some satellite orbits into the\nhost's equatorial plane, enhancing the fraction of satellites with co-planar\norbits. In fact, the orbital poles of co-planar satellites are tightly aligned\nwith the minor axis of the host halo.", "positive": "Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright,\n Star-Forming Galaxies with High Escape Fractions: The protagonists of cosmic reionization remain elusive. Faint star-forming\ngalaxies are leading candidates because they are numerous and may have\nsignificant ionizing photon escape fractions ($f_{esc}$). Here we update this\npicture via an empirical model that successfully predicts latest observations\n(e.g., the drop in star-formation density at z>8). We generate an ionizing\nspectrum for each galaxy in our model and constrain $f_{esc}$ using latest\nmeasurements of the reionization timeline (e.g., Ly$\\alpha$ damping of quasars\nand galaxies at z>7). Assuming a constant $f_{esc}$, we find $M_{UV}$<-13.5\ngalaxies need $f_{esc}=0.21^{+0.06}_{-0.04}$ to complete reionization. The\ninferred IGM neutral fraction is [0.9, 0.5, 0.1] at z=[8.2, 6.8, 6.2]$\\pm$0.2,\ni.e., the bulk of reionization transpires in 300 Myrs. Inspired by the emergent\nsample of Lyman Continuum (LyC) leakers that overwhelmingly displays\nhigher-than-average star-formation surface density ($\\Sigma$), we propose a\nmodel relating $f_{esc}$ to $\\Sigma$ and find\n$f_{esc}\\propto\\Sigma^{0.4\\pm0.1}$. Since $\\Sigma$ falls by ~2.5 dex between\nz=8 and z=0, our model explains the humble upper limits on $f_{esc}$ at lower\nredshifts and its required evolution to ~0.2 at z>6. Within this model,\nstrikingly, <5% of galaxies with $M_{UV}$<-18 (the `oligarchs') account for\n>80% of the reionization budget. In fact, faint sources ($M_{UV}$>-16) must be\nrelegated to a limited role to ensure high neutral fractions at z=7-8. Shallow\nfaint-end slopes of the UV luminosity function ($\\alpha$>-2) and/or $f_{esc}$\ndistributions skewed toward bright galaxies produce the required late and rapid\nreionization. We predict LyC leakers like COLA1 (z=6.6, $f_{esc}$~30%,\n$M_{UV}$=-21.5) become increasingly common towards z~6 and that the drivers of\nreionization do not lie hidden across the faint-end of the luminosity function,\nbut are already known to us. (abridged)" }, { "anchor": "Galaxy Luminosity Function of Dynamically Young Abell 119 Cluster:\n Probing the Cluster Assembly: We present the galaxy luminosity function (LF) of the Abell 119 cluster down\nto $M_r\\sim-14$ mag based on deep images in the $u$-, $g$-, and $r$-bands taken\nby using MOSAIC II CCD mounted on the Blanco 4m telescope at the CTIO. The\ncluster membership was accurately determined based on the radial velocity\ninformation as well as on the color-magnitude relation for bright galaxies and\nthe scaling relation for faint galaxies. The overall LF exhibits a bimodal\nbehavior with a distinct dip at $r\\sim18.5$ mag ($M_r\\sim-17.8$ mag), which is\nmore appropriately described by a two-component function. The shape of the LF\nstrongly depends on the cluster-centric distance and on the local galaxy\ndensity. The LF of galaxies in the outer, low-density region exhibits a steeper\nslope and more prominent dip compared with that of counterparts in the inner,\nhigh-density region. We found evidence for a substructure in the projected\ngalaxy distribution in which several overdense regions in the Abell 119 cluster\nappear to be closely associated with the surrounding, possible filamentary\nstructure. The combined LF of the overdense regions exhibits a two-component\nfunction with a distinct dip, while the LF of the central region is well\ndescribed by a single Schechter function. We suggest that, in the context of\nthe hierarchical cluster formation scenario, the observed overdense regions are\nthe relics of galaxy groups, retaining their two-component LFs with a dip,\nwhich acquired their shapes through galaxy merging process in group\nenvironments, before they fall into a cluster.", "positive": "A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE):\n JWST Reveals a Filamentary Structure around a z=6.61 Quasar: We present the first results from the JWST ASPIRE program (A SPectroscopic\nsurvey of biased halos In the Reionization Era). This program represents an\nimaging and spectroscopic survey of 25 reionization-era quasars and their\nenvironments by utilizing the unprecedented capabilities of NIRCam Wide Field\nSlitless Spectroscopy (WFSS) mode. ASPIRE will deliver the largest\n($\\sim280~{\\rm arcmin}^2$) galaxy redshift survey at 3-4 $\\mu$m among JWST\nCycle-1 programs and provide extensive legacy values for studying the formation\nof the earliest supermassive black holes (SMBHs), the assembly of galaxies,\nearly metal enrichment, and cosmic reionization. In this first ASPIRE paper, we\nreport the discovery of a filamentary structure traced by the luminous quasar\nJ0305-3150 and ten [OIII] emitters at $z=6.6$. This structure has a 3D galaxy\noverdensity of $\\delta_{\\rm gal}=12.6$ over 637 cMpc$^3$, one of the most\noverdense structures known in the early universe, and could eventually evolve\ninto a massive galaxy cluster. Together with existing VLT/MUSE and ALMA\nobservations of this field, our JWST observations reveal that J0305-3150 traces\na complex environment where both UV-bright and dusty galaxies are present, and\nindicate that the early evolution of galaxies around the quasar is not\nsimultaneous. In addition, we discovered 31 [OIII] emitters in this field at\nother redshifts, $5.3 10^(43) erg/s) and narrow (< 500\nkm/s) Ly alpha lines, and also a possible mini broad absorption line system of\nN V 1240 in the composite spectrum, which clearly separate them from typical\nquasars. On the other hand, the high-z galaxies have extremely high luminosity\n(M1450 ~ -24 to -22 mag) compared to other galaxies found at similar redshift.\nWith the discovery of these new classes of objects, we are opening up new\nparameter spaces in the high-z Universe. Further survey observations and\nfollow-up studies of the identified objects, including the construction of the\nquasar luminosity function at z ~ 6, are ongoing." }, { "anchor": "The Formation of Star and Planetary Systems: New Results from Spitzer: Protoplanetary disks are thought to be the birth places of planetary systems.\nThe formation and the subsequent evolution of protoplanetary disks are\nregulated by the star formation process, which begins with the collapse of a\ncloud core to form a central protostar surrounded by a disk and an overlying\nenvelope. In the protostellar phase, most of the envelope material is\ntransferred onto the star through the disk during episodic, high accretion\nevents. The initial conditions for planet formation in protoplanetary disks are\nlikely set by the details of these processes. In this contribution, I will\nreview some of the new observational results from Spitzer on protostellar\nevolution and the structure and evolution of protoplanetary disks surrounding\nyoung stars in the nearby star forming regions. The implications of these\nresults for planet formation and eventual disk dissipation are discussed.", "positive": "Simulating realistic disk galaxies with a novel sub-resolution ISM model: We present results of cosmological simulations of disk galaxies carried out\nwith the GADGET-3 TreePM+SPH code, where star formation and stellar feedback\nare described using our MUlti Phase Particle Integrator (MUPPI) model. This\ndescription is based on simple multi-phase model of the interstellar medium at\nunresolved scales, where mass and energy flows among the components are\nexplicitly followed by solving a system of ordinary differential equations.\nThermal energy from SNe is injected into the local hot phase, so as to avoid\nthat it is promptly radiated away. A kinetic feedback prescription generates\nthe massive outflows needed to avoid the over-production of stars. We use two\nsets of zoomed-in initial conditions of isolated cosmological halos with masses\n(2-3) * 10^{12} Msun, both available at several resolution levels. In all cases\nwe obtain spiral galaxies with small bulge-over-total stellar mass ratios (B/T\n\\approx 0.2), extended stellar and gas disks, flat rotation curves and\nrealistic values of stellar masses. Gas profiles are relatively flat, molecular\ngas is found to dominate at the centre of galaxies, with star formation rates\nfollowing the observed Schmidt-Kennicutt relation. Stars kinematically\nbelonging to the bulge form early, while disk stars show a clear inside-out\nformation pattern and mostly form after redshift z=2. However, the baryon\nconversion efficiencies in our simulations differ from the relation given by\nMoster et al. (2010) at a 3 sigma level, thus indicating that our stellar disks\nare still too massive for the Dark Matter halo in which they reside. Results\nare found to be remarkably stable against resolution. This further demonstrates\nthe feasibility of carrying out simulations producing a realistic population of\ngalaxies within representative cosmological volumes, at a relatively modest\nresolution." }, { "anchor": "The Search for Multiple Populations in Magellanic Cloud Clusters III: No\n evidence for Multiple Populations in the SMC cluster NGC 419: We present the third paper about our ongoing HST survey for the search for\nmultiple stellar populations (MPs) within Magellanic Cloud clusters. We report\nhere the analysis of NGC 419, a $\\sim 1.5$ Gyr old, massive ($\\gtrsim 2 \\times\n10^5 \\, {\\rm M_{\\odot}}$) star cluster in the Small Magellanic Cloud (SMC). By\ncomparing our photometric data with stellar isochrones, we set a limit on\n[N/Fe] enhancement of $\\lesssim$+0.5 dex and hence we find that no MPs are\ndetected in this cluster. This is surprising because, in the first two papers\nof this series, we found evidence for MPs in 4 other SMC clusters (NGC 121;\nLindsay 1, NGC 339, NGC 416), aged from 6 Gyr up to $\\sim 10-11$ Gyr. This\nfinding raises the question whether age could play a major role in the MPs\nphenomenon. Additionally, our results appear to exclude mass or environment as\nthe only key factors regulating the existence of a chemical enrichment, since\nall clusters studied so far in this survey are equally massive ($\\sim 1-2\n\\times 10^5 \\, {\\rm M_{\\odot}}$) and no particular patterns are found when\nlooking at their spatial distribution in the SMC.", "positive": "Not so lumpy after all: modeling the depletion of dark matter subhalos\n by Milky Way-like galaxies: Among the most important goals in cosmology is detecting and quantifying\nsmall ($M_{\\rm halo}\\simeq10^{6-9}~\\mathrm{M}_\\odot$) dark matter (DM)\nsubhalos. Current probes around the Milky Way (MW) are most sensitive to such\nsubstructure within $\\sim20$ kpc of the halo center, where the galaxy\ncontributes significantly to the potential. We explore the effects of baryons\non subhalo populations in $\\Lambda$CDM using cosmological zoom-in baryonic\nsimulations of MW-mass halos from the Latte simulation suite, part of the\nFeedback In Realistic Environments (FIRE) project. Specifically, we compare\nsimulations of the same two halos run using (1) DM-only (DMO), (2) full\nbaryonic physics, and (3) DM with an embedded disk potential grown to match the\nFIRE simulation. Relative to baryonic simulations, DMO simulations contain\n$\\sim2\\times$ as many subhalos within 100 kpc of the halo center; this excess\nis $\\gtrsim5\\times$ within 25 kpc. At $z=0$, the baryonic simulations are\ncompletely devoid of subhalos down to $3\\times10^6~\\mathrm{M}_\\odot$ within\n$15$ kpc of the MW-mass galaxy, and fewer than 20 surviving subhalos have\norbital pericenters <20 kpc. Despite the complexities of baryonic physics, the\nsimple addition of an embedded central disk potential to DMO simulations\nreproduces this subhalo depletion, including trends with radius, remarkably\nwell. Thus, the additional tidal field from the central galaxy is the primary\ncause of subhalo depletion. Subhalos on radial orbits that pass close to the\ncentral galaxy are preferentially destroyed, causing the surviving subhalo\npopulation to have tangentially biased orbits compared to DMO predictions. Our\nmethod of embedding a disk potential in DMO simulations provides a fast and\naccurate alternative to full baryonic simulations, thus enabling suites of\ncosmological simulations that can provide accurate and statistical predictions\nof substructure populations." }, { "anchor": "LISA Galactic Binaries in the Roman Galactic Bulge Time-Domain Survey: Short-period Galactic white dwarf binaries detectable by LISA are the only\nguaranteed persistent sources for multi-messenger gravitational-wave astronomy.\nLarge-scale surveys in the 2020s present an opportunity to conduct preparatory\nscience campaigns to maximize the science yield from future multi-messenger\ntargets. The Nancy Grace Roman Space Telescope Galactic Bulge Time Domain\nSurvey will (in its Reference Survey design) image seven fields in the Galactic\nBulge approximately 40,000 times each. Although the Reference Survey cadence is\noptimized for detecting exoplanets via microlensing, it is also capable of\ndetecting short-period white dwarf binaries. In this paper, we present\nforecasts for the number of detached short-period binaries the Roman Galactic\nBulge Time Domain Survey will discover and the implications for the design of\nelectromagnetic surveys. Although population models are highly uncertain, we\nfind a high probability that the baseline survey will detect of order ~5\ndetached white dwarf binaries. The Reference Survey would also have a\n$\\gtrsim20\\%$ chance of detecting several known benchmark white dwarf binaries\nat the distance of the Galactic Bulge.", "positive": "What drives galaxy quenching? A deep connection between galaxy\n kinematics and quenching in the local Universe: We develop a 2D inclined rotating disc model, which we apply to the stellar\nvelocity maps of 1862 galaxies taken from the MaNGA survey (SDSS public Data\nRelease 15). We use a random forest classifier to identify the kinematic\nparameters that are most connected to galaxy quenching. We find that kinematic\nparameters that relate predominantly to the disc (such as the mean rotational\nvelocity) and parameters that characterise whether a galaxy is rotation- or\ndispersion-dominated (such as the ratio of rotational velocity to velocity\ndispersion) are not fundamentally linked to the quenching of star formation.\nInstead, we find overwhelmingly that it is the absolute level of velocity\ndispersion (a property that relates primarily to a galaxy's bulge/spheroidal\ncomponent) that is most important for separating star forming and quenched\ngalaxies. Furthermore, a partial correlation analysis shows that many commonly\ndiscussed correlations between galaxy properties and quenching are spurious,\nand that the fundamental correlation is between quenching and velocity\ndispersion. In particular, we find that at fixed velocity dispersion, there is\nonly a very weak dependence of quenching on the disc properties, whereby more\ndiscy galaxies are slightly more likely to be forming stars. By invoking the\ntight relationship between black hole mass and velocity dispersion, and noting\nthat black hole mass traces the total energy released by AGN, we argue that\nthese data support a scenario in which quenching occurs by preventive feedback\nfrom AGN. The kinematic measurements from this work are publicly available." }, { "anchor": "Formation of disks with long-lived spiral arms from violent\n gravitational dynamics: By means of simple dynamical experiments we study the combined effect of\ngravitational and gas dynamics in the evolution of an initially\nout-of-equilibrium, uniform and rotating massive over-density thought of as in\nisolation. The rapid variation of the system mean-field potential makes the\npoint like particles (PPs), which interact only via Newtonian gravity, form a\nquasistationary thick disk dominated by rotational motions surrounded by far\nout-of-equilibrium spiral arms. On the other side, the gas component is\nsubjected to compression shocks and radiative cooling so as to develop a much\nflatter disk, where rotational motions are coherent and the velocity dispersion\nis smaller than that of PPs. Around such gaseous disk long-lived, but\nnonstationary, spiral arms form: these are made of gaseous particles that move\ncoherently because have acquired a specific phase-space correlation during the\ngravitational collapse phase. Such a phase-space correlation represents a\nsignature of the violent origin of the arms and implies both the motion of\nmatter and the transfer of energy. On larger scales, where the radial velocity\ncomponent is significantly larger than the rotational one, the gas follows the\nsame out-of-equilibrium spiral arms traced by PPs. We finally outline the\nastrophysical and cosmological implications of our results.", "positive": "A Sino-German $\u03bb$6\\ cm polarization survey of the Galactic plane.\n V. Large supernova remnants: Observations of large supernova remnants (SNRs) at high frequencies are rare,\nbut provide valuable information about their physical properties. The total\nintensity and polarization properties of 16 large SNRs in the Galactic plane\nwere investigated based on observations of the Urumqi $\\lambda$6\\ cm\npolarization survey of the Galactic plane with an angular resolution of\n9$\\farcm$5. We extracted total intensity and linear polarization maps of large\nSNRs from the Urumqi $\\lambda$6\\ cm survey, obtained their integrated flux\ndensities, and derived the radio spectra in context with previously published\nflux densities at various frequencies. In particular, Effelsberg $\\lambda$11\\\ncm and $\\lambda$21\\ cm survey data were used for calculating integrated flux\ndensities. The $\\lambda$6\\ cm polarization data also delineate the magnetic\nfield structures of the SNRs. We present the first total intensity maps at\n$\\lambda$6\\ cm for SNRs G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO\n42.05.01), G205.5+0.5 (Monoceros Nebula) and G206.9+2.3 (PKS 0646+06) and the\nfirst polarization measurements at $\\lambda$6\\ cm for SNRs G82.2+5.3 (W63),\nG106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO 42.05.01), G205.5+0.5\n(Monoceros Nebula) and G206.9+2.3 (PKS 0646+06). Most of the newly derived\nintegrated radio spectra are consistent with previous results. The new flux\ndensities obtained from the Urumqi $\\lambda$6\\ cm, Effelsberg $\\lambda$11\\ cm\nand $\\lambda$21\\ cm surveys are crucial to determine the spectra of SNR\nG65.1+0.6, G69.0+2.7 (CTB 80), G93.7-0.2 and G114.3+0.3. We find that\nG192.8$-$1.1 (PKS 0607+17) consists of background sources, \\ion{H}{II} regions\nand the extended diffuse emission of thermal nature, and conclude that\nG192.8$-$1.1 is not a SNR." }, { "anchor": "Radio perspectives on the Monoceros SNR G205.5+0.5: The Monoceros Loop (SNR G205.5+0.5) is a large shell-type supernova remnant\nlocated in the Rosette Complex region. It was suggested to be interacting with\nthe Rosette Nebula. We aim to re-examine the radio spectral index and its\nspatial variation over the Monoceros SNR, and study its properties of evolution\nwithin the complex interstellar medium. We extracted radio continuum data for\nthe Monoceros complex region from the Effelsberg 21 cm and 11 cm surveys and\nthe Urumqi 6 cm polarization survey. We used the new Arecibo GALFA-HI survey\ndata with much higher resolution and sensitivity than that previously available\nto identify the HI shell related with the SNR. Multi-wavelengths data are\nincluded to investigate the properties of the SNR. The spectral index $\\alpha$\n($S_{\\nu}\\propto\\nu^{\\alpha}$) averaged over the SNR is $-0.41 \\pm$0.16. The\nTT-plots and the distribution of $\\alpha$ over the SNR show spatial variations\nwhich steepen towards the inner western filamentary shell. Polarized emission\nis prominent on the western filamentary shell region. The RM there is estimated\nto be about 30$\\pm$77n rad m$^{-2}$, where the n=1 solution is preferred, and\nthe magnetic field has a strength of about 9.5 $\\mu$G. From the HI channel\nmaps, further evidence is provided for an interaction between the Monoceros SNR\nand the Rosette Nebula. We identify partial neutral hydrogen shell structures\nin the northwestern region at LSR velocities of +15 km s$^{-1}$ circumscribing\nthe continuum emission. The HI shell has swept up a mass of about 4000\nM$_{\\odot}$ for a distance of 1.6 kpc. The western HI shell, well associated\nwith the dust mission, is found to lie outside of the radio shell. We suggest\nthat the Monoceros SNR is evolving within a cavity blown-out by the progenitor,\nand has triggered part of the star formation in the Rosette Nebula.", "positive": "Stellar Masses of Giant Clumps in CANDELS and Simulated Galaxies Using\n Machine Learning: A significant fraction of high redshift star-forming disc galaxies are known\nto host giant clumps, whose nature and role in galaxy evolution are yet to be\nunderstood. In this work we first present a new method based on neural networks\nto detect clumps in galaxy images. We use this method to detect clumps in the\nrest-frame optical and UV images of a complete sample of $\\sim1500$ star\nforming galaxies at $1}50$) needed to impose a meaningful constraint on the\ncluster velocity dispersion and map its members over a large field of view. Our\n$\\Lambda$CDM cosmological simulation suggests that this cluster will most\nlikely evolve into a Virgo-like cluster with ${\\rm M_{vir}}{=}10^{14.4\\pm0.3}\n{\\rm M_\\odot}$ ($68\\%$ confidence) at $z\\sim$ 0. The theoretical expectation of\nfinding such a cluster is $\\sim$ $4\\%$. Our results demonstrate the feasibility\nof studying galaxy clusters at $z > 2$ in the same detailed manner using\nmulti-object NIR spectrographs as has been done in the optical in lower\nredshift clusters." }, { "anchor": "Far-infrared and accretion luminosities of the present-day active\n galactic nuclei: We investigate the relation between star formation (SF) and black hole\naccretion luminosities, using a sample of 492 type-2 active galactic nuclei\n(AGNs) at z < 0.22, which are detected in the far-infrared (FIR) surveys with\nAKARI and Herschel. We adopt FIR luminosities at 90 and 100 um as SF\nluminosities, assuming the proposed linear proportionality of star formation\nrate with FIR luminosities. By estimating AGN luminosities from [OIII]5007 and\n[OI]6300 emission lines, we find a positive linear trend between FIR and AGN\nluminosities over a wide dynamical range. This result appears to be\ninconsistent with the recent reports that low-luminosity AGNs show essentially\nno correlation between FIR and X-ray luminosities, while the discrepancy is\nlikely due to the Malmquist and sample selection biases. By analyzing the\nspectral energy distribution, we find that pure-AGN candidates, of which FIR\nradiation is thought to be AGN-dominated, show significantly low-SF activities.\nThese AGNs hosted by low-SF galaxies are rare in our sample (~ 1%). However,\nthe low fraction of low-SF AGN is possibly due to observational limitations\nsince the recent FIR surveys are insufficient to examine the population of\nhigh-luminosity AGNs hosted by low-SF galaxies.", "positive": "Effects of galaxy environment on merger fraction: Aims. In this work, we intend to examine how environment influences the\nmerger fraction, from the low density field environment to higher density\ngroups and clusters. We also aim to study how the properties of a group or\ncluster, as well as the position of a galaxy in the group or cluster,\ninfluences the merger fraction.\n Methods. We identified galaxy groups and clusters in the North Ecliptic Pole\nusing a friends-of-friends algorithm and the local density. Once identified, we\ndetermined the central galaxies, group radii, velocity dispersions, and group\nmasses of these groups and clusters. Merging systems were identified with a\nneural network as well as visually. With these, we examined how the merger\nfraction changes as the local density changes for all galaxies as well as how\nthe merger fraction changes as the properties of the groups or clusters change.\n Results. We find that the merger fraction increases as local density\nincreases and decreases as the velocity dispersion increases, as is often found\nin literature. A decrease in merger fraction as the group mass increases is\nalso found. We also find groups with larger radii have higher merger fractions.\nThe number of galaxies in a group does not influence the merger fraction.\n Conclusions. The decrease in merger fraction as group mass increases is a\nresult of the link between group mass and velocity dispersion. Hence, this\ndecrease of merger fraction with increasing mass is a result of the decrease of\nmerger fraction with velocity dispersion. The increasing relation between group\nradii and merger fraction may be a result of larger groups having smaller\nvelocity dispersion at a larger distance from the centre or larger groups\nhosting smaller, infalling groups with more mergers. However, we do not find\nevidence of smaller groups having higher merger fractions." }, { "anchor": "The Infrared Database of Extragalactic Observables from Spitzer I: the\n redshift catalog: This is the first of a series of papers on the Infrared Database of\nExtragalactic Observables from Spitzer (IDEOS). In this work we describe the\nidentification of optical counterparts of the infrared sources detected in\nSpitzer Infrared Spectrograph (IRS) observations, and the acquisition and\nvalidation of redshifts. The IDEOS sample includes all the spectra from the\nCornell Atlas of Spitzer/IRS Sources (CASSIS) of galaxies beyond the Local\nGroup. Optical counterparts were identified from correlation of the extraction\ncoordinates with the NASA Extragalactic Database (NED). To confirm the optical\nassociation and validate NED redshifts, we measure redshifts with unprecedented\naccuracy on the IRS spectra ({\\sigma}(dz/(1+z))=0.0011) by using an improved\nversion of the maximum combined pseudo-likelihood method (MCPL). We perform a\nmulti-stage verification of redshifts that considers alternate NED redshifts,\nthe MCPL redshift, and visual inspection of the IRS spectrum. The statistics is\nas follows: the IDEOS sample contains 3361 galaxies at redshift 010^5Mo) in a moderately early dynamical evolutionary stage, with observed\nextra-tidal structures.", "positive": "Ultraviolet Halos Around Spiral Galaxies. I. Morphology: We examine ultraviolet halos around a sample of highly inclined galaxies\nwithin 25 Mpc to measure their morphology and luminosity. Despite contamination\nfrom galactic light scattered into the wings of the point-spread function, we\nfind that UV halos occur around each galaxy in our sample. Around most galaxies\nthe halos form a thick, diffuse disk-like structure, but starburst galaxies\nwith galactic superwinds have qualitatively different halos that are more\nextensive and have filamentary structure. The spatial coincidence of the UV\nhalos above star-forming regions, the lack of consistent association with\noutflows or extraplanar ionized gas, and the strong correlation between the\nhalo and galaxy UV luminosity suggest that the UV light is an extragalactic\nreflection nebula. UV halos may thus represent 1-10 million solar masses of\ndust within 2-10 kpc of the disk, whose properties may change with height in\nstarburst galaxies." }, { "anchor": "The dangers of being trigger--happy: We examine the evidence offered for triggered star formation against the\nbackdrop provided by recent numerical simulations of feedback from massive\nstars at or below giant molecular cloud sizescales. We compile a catalogue of\nsixty--seven observational papers, mostly published over the last decade, and\nexamine the signposts most commonly used to infer the presence of triggered\nstar formation. We then determine how well these signposts perform in a recent\nsuite of hydrodynamic simulations of star formation including feedback from\nO--type stars performed by Dale et al (2012a, b, 2013a, b, 2014). We find that\nnone of the observational markers improve the chances of correctly identifying\na given star as triggered by more than factors of two at most. This limits the\nfidelity of these techniques in interpreting star formation histories. We\ntherefore urge caution in interpreting observations of star formation near\nfeedback--driven structures in terms of triggering.", "positive": "The Post-Pericenter Evolution of the Galactic Center Source G2: In early 2014 the fast-moving near-infrared source G2 reached its closest\napproach to the supermassive black hole Sgr A* in the Galactic Center. We\nreport on the evolution of the ionized gaseous component and the dusty\ncomponent of G2 immediately after this event, revealed by new observations\nobtained in 2015 and 2016 with the SINFONI integral field spectrograph and the\nNACO imager at the ESO VLT. The spatially resolved dynamics of the Br$\\gamma$\nline emission can be accounted for by the ballistic motion and tidal shearing\nof a test-particle cloud that has followed a highly eccentric Keplerian orbit\naround the black hole for the last 12 years. The non-detection of a drag force\nor any strong hydrodynamic interaction with the hot gas in the inner accretion\nzone limits the ambient density to less than a few 10$^3$ cm$^{-3}$ at the\ndistance of closest approach (1500 $R_s$), assuming G2 is a spherical cloud\nmoving through a stationary and homogeneous atmosphere. The dust continuum\nemission is unresolved in L'-band, but stays consistent with the location of\nthe Br$\\gamma$ emission. The total luminosity of the Br$\\gamma$ and L' emission\nhas remained constant to within the measurement uncertainty. The nature and\norigin of G2 are likely related to that of the precursor source G1, since their\norbital evolution is similar, though not identical. Both object are also likely\nrelated to a trailing tail structure, which is continuously connected to G2\nover a large range in position and radial velocity." }, { "anchor": "Fractal dimension and turbulence in Giant HII Regions: We have measured the fractal dimensions of the Giant HII Regions Hubble X and\nHubble V in NGC6822 using images obtained with the Hubble's Wide Field\nPlanetary Camera 2 (WFPC2). These measures are associated with the turbulence\nobserved in these regions, which is quantified through the velocity dispersion\nof emission lines in the visible. Our results suggest low turbulence behaviour.", "positive": "Is there a compact companion orbiting the late O-type binary star HD\n 164816?: We present a multi-wavelength (X-ray, $\\gamma$-ray, optical and radio) study\nof HD 194816, a late O-type X-ray detected spectroscopic binary. X-ray spectra\nare analyzed and the X-ray photon arrival times are checked for pulsation. In\naddition, newly obtained optical spectroscopic monitoring data on HD 164816 are\npresented. They are complemented by available radio data from several large\nscale surveys as well as the \\emph{FERMI} $\\gamma$-ray data from its\n\\emph{Large Area Telescope}. We report the detection of a low energy excess in\nthe X-ray spectrum that can be described by a simple absorbed blackbody model\nwith a temperature of $\\sim$ 50 eV as well as a 9.78 s pulsation of the X-ray\nsource. The soft X-ray excess, the X-ray pulsation, and the kinematical age\nwould all be consistent with a compact object like a neutron star as companion\nto HD 164816. The size of the soft X-ray excess emitting area is consistent\nwith a circular region with a radius of about 7 km, typical for neutron stars,\nwhile the emission measure of the remaining harder emission is typical for late\nO-type single or binary stars. If HD 164816 includes a neutron star born in a\nsupernova, this supernova should have been very recent and should have given\nthe system a kick, which is consistent with the observation that the star HD\n164816 has a significantly different radial velocity than the cluster mean. In\naddition we confirm the binarity of HD 164816 itself by obtaining an orbital\nperiod of 3.82 d, projected masses $m_1 {\\rm sin}^{3} i$ = 2.355(69) M$_\\odot$,\n$m_2 {\\rm sin}^{3} i$ = 2.103(62) M$_\\odot$ apparently seen at low inclination\nangle, determined from high-resolution optical spectra." }, { "anchor": "The ALMaQUEST Survey: III. Scatter in the resolved star forming main\n sequence is primarily due to variations in star formation efficiency: Using a sample of 11,478 spaxels in 34 galaxies with molecular gas, star\nformation and stellar maps taken from the ALMA-MaNGA QUEnching and STar\nformation (ALMaQUEST) survey, we investigate the parameters that correlate with\nvariations in star formation rates on kpc scales. We use a combination of\ncorrelation statistics and an artificial neural network to quantify the\nparameters that drive both the absolute star formation rate surface density\n(Sigma_SFR), as well as its scatter around the resolved star forming main\nsequence (Delta Sigma_SFR). We find that Sigma_SFR is primarily regulated by\nmolecular gas surface density (Sigma_H2) with a secondary dependence on stellar\nmass surface density (Sigma_*), as expected from an `extended Kennicutt-Schmidt\nrelation'. However, Delta Sigma_SFR is driven primarily by changes in star\nformation efficiency (SFE), with variations in gas fraction playing a secondary\nrole. Taken together, our results demonstrate that whilst the absolute rate of\nstar formation is primarily set by the amount of molecular gas, the variation\nof star formation rate above and below the resolved star forming main sequence\n(on kpc scales) is primarily due to changes in SFE.", "positive": "Modelling the gas kinematics of an atypical Lyman-alpha emitting compact\n dwarf galaxy: Star-forming Compact Dwarf Galaxies (CDGs) resemble the expected pristine\nconditions of the first galaxies in the Universe and are the best systems to\ntest models on primordial galaxy formation and evolution. Here we report on one\nof such CDGs, Tololo 1214-277, which presents a broad, single peaked, highly\nsymmetric Ly$\\alpha$ emission line that had evaded theoretical interpretation\nso far. In this paper we reproduce for the first time these line features with\ntwo different physically motivated kinematic models: an interstellar medium\ncomposed by outflowing clumps with random motions and an homogeneous gaseous\nsphere undergoing solid body rotation. The multiphase model requires a clump\nvelocity dispersion of $54.3\\pm 0.6$ km s$^{-1}$ with outflows of $54.3\\pm 5.1$\nkm s$^{-1}$, while the bulk rotation velocity is constrained to be\n$348^{+75}_{-48}$ km s$^{-1}$. We argue that the results from the multiphase\nmodel provide a correct interpretation of the data. In that case the clump\nvelocity dispersion implies a dynamical mass of $2\\times 10^{9}$ M$_{\\odot}$,\nten times its baryonic mass. If future kinematic maps of Tololo 1214-277\nconfirm the velocities suggested by the multiphase model, it would provide\nadditional support to expect such kinematic state in primordial galaxies,\nopening the opportunity to use the models and methods presented in this paper\nto constrain the physics of star formation and feedback in the early generation\nof Ly-$\\alpha$ emitting galaxies." }, { "anchor": "A multi-band AGN-SFG classifier for extragalactic radio surveys using\n machine learning: Extragalactic radio continuum surveys play an increasingly more important\nrole in galaxy evolution and cosmology studies. While radio galaxies and radio\nquasars dominate at the bright end, star-forming galaxies (SFGs) and\nradio-quiet Active Galactic Nuclei (AGNs) are more common at fainter flux\ndensities. Our aim is to develop a machine learning classifier that can\nefficiently and reliably separate AGNs and SFGs in radio continuum surveys. We\nperform supervised classification of SFGs vs AGNs using the Light Gradient\nBoosting Machine (LGBM) on three LOFAR Deep Fields (Lockman Hole, Bootes and\nELAIS-N1), which benefit from a wide range of high-quality multi-wavelength\ndata and classification labels derived from extensive spectral energy\ndistribution (SED) analyses. Our trained model has a precision of 0.92(0.01)\nand a recall of 0.87(0.02) for SFGs. For AGNs, the model has slightly worse\nperformance, with a precision of 0.87(0.02) and recall of 0.78(0.02). These\nresults demonstrate that our trained model can successfully reproduce the\nclassification labels derived from detailed SED analysis. The model performance\ndecreases towards higher redshifts, mainly due to smaller training sample\nsizes. To make the classifier more adaptable to other radio galaxy surveys, we\nalso investigate how our classifier performs with a poorer multi-wavelength\nsampling of the SED. In particular, we find that the far-infrared (FIR) and\nradio bands are of great importance. We also find that higher S/N in some\nphotometric bands leads to a significant boost in the model's performance. In\naddition to using the 150 MHz radio data, our model can also be used with 1.4\nGHz radio data. Converting 1.4 GHz to 150 MHz radio data reduces performance by\nabout 4% in precision and 3% in recall. The final trained model is publicly\navailable at https://github.com/Jesper-Karsten/MBASC", "positive": "Metal-poor star formation at $z>6$ with JWST: new insight into hard\n radiation fields and nitrogen enrichment on 20 pc scales: Nearly a decade ago, we began to see indications that reionization-era\ngalaxies power hard radiation fields rarely seen at lower redshift. Most\nstriking were detections of nebular CIV emission in what appeared to be typical\nlow mass galaxies, requiring an ample supply of 48 eV photons to triply ionize\ncarbon. The nature of this population has long remained unclear owing to\nlimitations of ground-based spectroscopy. We have obtained deep JWST/NIRSpec\nR=1000 spectroscopy of the two z>6 CIV-emitting galaxies known prior to JWST.\nHere we present a rest-UV to optical spectrum of one of these two systems, the\nmultiply-imaged z=6.1 lensed galaxy RXCJ2248-ID. NIRCam imaging reveals two\ncompact (<22pc) clumps separated by 220pc, with one comprising a dense\nconcentration of massive stars ($>10,400M_{\\odot}$/yr/kpc$^2$) formed in a\nrecent burst. We stack spectra of 3 images of the galaxy (J=24.8-25.9),\nyielding a very deep spectrum providing a high S/N template of strong emission\nline sources at z>6. The spectrum reveals narrow high ionization lines (HeII,\nCIV, NIV]) with line ratios consistent with powering by massive stars. The\nrest-optical spectrum is dominated by very strong emission lines ([OIII]\nEW=2800\\AA), albeit with weak emission from low-ionization transitions\n([OIII]/[OII]=184). The electron density is found to be very\nhigh($6.4-31\\times10^4$cm$^{-3}$) based on three UV transitions. The ionized\ngas is metal poor ($12+\\log(\\rm O/H)=7.43^{+0.17}_{-0.09}$), yet highly\nenriched in nitrogen ($\\log(\\rm N/O)=-0.39^{+0.11}_{-0.10}$). The spectrum\nappears broadly similar to that of GNz11 at z=10.6, without showing the same\nAGN signatures. We suggest that the hard radiation field and rapid nitrogen\nenrichment may be a short-lived phase that many z>6 galaxies go through as they\nundergo strong bursts of star formation. We comment on the potential link of\nsuch spectra to globular cluster formation." }, { "anchor": "A new bright z=6.82 quasar discovered with VISTA: VHS J0411-0907: We present the discovery of a new $z \\sim 6.8$ quasar discovered with the\nnear-IR VISTA Hemisphere Survey (VHS) which has been spectroscopically\nconfirmed by the ESO New Technology Telescope (NTT) and the Magellan telescope.\nThis quasar has been selected by spectral energy distribution (SED)\nclassification using near infrared data from VISTA, optical data from\nPan-STARRS, and mid-IR data from WISE. The SED classification algorithm is used\nto statistically rank two classes; foreground Galactic low-mass stars and high\nredshift quasars, prior to spectroscopic observation. Forced photometry on\nPan-STARRS pixels for VHS J0411-0907 allows to improve the SED classification\nreduced-$\\chi^2$ and photometric redshift. VHS J0411-0907 ($z=6.82$, $y_{AB} =\n20.1$ mag, $J_{AB} = 20.0$ mag) has the brightest J-band continuum magnitude of\nthe nine known quasars at $z > 6.7$ and is currently the highest redshift\nquasar detected in the Pan-STARRS survey. This quasar has one of the lowest\nblack hole mass ($M_{\\rm{BH}}= (6.13 \\pm 0.51)\\times 10^8\\:\\mathrm{M_{\\odot}}$)\nand the highest Eddington ratio ($2.37\\pm0.22$) of the known quasars at\n$z>6.5$. The high Eddington ratio indicates that some very high-$z$ quasars are\nundergoing super Eddington accretion. We also present coefficients of the best\npolynomials fits for colours vs spectral type on the Pan-STARRS, VISTA and WISE\nsystem for MLT dwarfs and present a forecast for the expected numbers of\nquasars at $z>6.5$.", "positive": "Chemodynamical Simulations of the Milky Way Galaxy: We present chemodynamical simulations of a Milky Way-type galaxy using a\nself-consistent hydrodynamical code that includes supernova feedback and\nchemical enrichment, and predict the spatial distribution of elements from\nOxygen to Zinc. In the simulated galaxy, the kinematical and chemical\nproperties of the bulge, disk, and halo are consistent with the observations.\nThe bulge formed from the assembly of subgalaxies at z>3, and has higher\n[alpha/Fe] ratios because of the small contribution from Type Ia Supernovae.\nThe disk formed with a constant star formation over 13 Gyr, and shows a\ndecreasing trend of [alpha/Fe] and increasing trends of [(Na,Al,Cu,Mn)/Fe]\nagainst [Fe/H]. However, the thick disk stars tend to have higher [alpha/Fe]\nand lower [Mn/Fe] than thin disk stars. We also predict the frequency\ndistribution of elemental abundance ratios as functions of time and location,\nwhich can be directly compared with galactic archeology projects such as\nHERMES." }, { "anchor": "The faint end of the red sequence galaxy luminosity function: unveiling\n surface brightness selection effects with the CLASH clusters: Characterizing the evolution of the faint end of the cluster red sequence\n(RS) galaxy luminosity function (GLF) with redshift is a milestone in\nunderstanding galaxy evolution. However, the community is still divided in that\nrespect, hesitating between an enrichment of the RS due to efficient quenching\nof blue galaxies from $z\\sim1$ to present-day or a scenario in which the RS is\nbuilt at a higher redshift and does not evolve afterwards. Recently, it has\nbeen proposed that surface brightness (SB) selection effects could possibly\nsolve the literature disagreement, accounting for the diminishing of the RS\nfaint population in ground based observations. We investigate this hypothesis\nby comparing the RS GLFs of 16 CLASH clusters computed independently from\nground-based Subaru/Suprime-Cam and HST/ACS images in the redshift range\n$0.187\\leq z\\leq0.686$. We stack individual cluster GLFs in redshift and mass\nbins.\n We find similar RS GLFs for space and ground based data, with a difference of\n0.2$\\sigma$ in the faint end parameter $\\alpha$ when stacking all clusters\ntogether and a maximum difference of 0.9$\\sigma$ in the case of the high\nredshift stack, demonstrating a weak dependence on the type of observations in\nthe probed range of redshift and mass. When considering the full sample, we\nestimate $\\alpha = -0.76 \\pm 0.07$ and $\\alpha = -0.78 \\pm 0.06$ with HST and\nSubaru respectively. We note a mild variation of the faint end with redshift at\na 1.7$\\sigma$ and 2.6$\\sigma$ significance. We investigate the effect of SB\ndimming by simulating our low redshift galaxies at high redshift. We measure an\nevolution in the faint end slope of less than 1$\\sigma$ in this case, implying\nthat the observed signature is moderately larger than one would expect from SB\ndimming alone, and indicating a true evolution in the faint end slope.\n(Abridged...)", "positive": "An Intriguing Globular Cluster in the Galactic Bulge from the VVV Survey: Recent near-IR Surveys have discovered a number of new bulge globular cluster\n(GC) candidates that need to be further investigated. Our main objective is to\nuse public data from the Gaia Mission, VVV, 2MASS and WISE in order to measure\nthe physical parameters of Minni48, a new candidate GC located in the inner\nbulge of the Galaxy at l=359.35 deg, b=2.79 deg. Even though there is a bright\nforeground star contaminating the field, the cluster appears quite bright in\nnear- and mid-IR images. We obtain deep decontaminated optical and near-IR\ncolour-magnitude diagrams (CMDs) for this cluster. The heliocentric cluster\ndistance is determined from the red clump (RC) and the red giant branch (RGB)\ntip magnitudes in the near-IR CMD, while the cluster metallicity is estimated\nfrom the RGB slope and the fit to theoretical isochrones. The GC size is found\nto be r = 6' +/- 1', while reddening and extinction values are E(J-Ks)=0.60 +/-\n0.05 mag, A_G=3.23 +/- 0.10 mag, A_Ks=0.45 +/- 0.05 mag. The resulting mean\nGaia proper motions are PMRA=-3.5 +/- 0.5 mas/yr, PMDEC=-6.0 +/- 0.5 mas/yr.\nThe IR magnitude of the RC yields an accurate distance modulus estimate of\n(m-M)_0=14.61 mag, equivalent to a distance D=8.4 +/- 1.0 kpc. This is\nconsistent with the optical distance estimate: (m-M)_0=14.67 mag, D=8.6 +/- 1.0\nkpc, and with the RGB tip distance: (m-M)_0=14.45 mag, D=7.8 +/- 1.0 kpc. The\nderived metallicity is [Fe/H]=-0.20 +/- 0.30 dex. A good fit to the PARSEC\nstellar isochrones is obtained in all CMDs using Age = 10 +/- 2 Gyr. The total\nabsolute magnitude of this GC is estimated to be M_Ks= -9.04 +/- 0.66 mag.\nBased on its position, kinematics, metallicity and age, we conclude that\nMinni48 is a genuine GC, similar to other well known metal-rich bulge GCs. It\nis located at a projected Galactocentric angular distance of 2.9 deg,\nequivalent to 0.4 kpc, being one of the closest GCs to the Galactic centre." }, { "anchor": "Uchuu-$\u03bd^2$GC galaxies and AGN: Cosmic variance forecasts of\n high-redshift AGN for JWST, Euclid, and LSST: Measurements of the luminosity function of active galactic nuclei (AGN) at\nhigh redshift ($z\\gtrsim 6$) are expected to suffer from field-to-field\nvariance, including cosmic and Poisson variances. Future surveys, such as those\nfrom the Euclid telescope and James Webb Space Telescope (JWST), will also be\naffected by field variance. We use the Uchuu simulation, a state-of-the-art\ncosmological $N$-body simulation with 2.1 trillion particles in a volume of\n$25.7~\\mathrm{Gpc}^3$, combined with a semi-analytic galaxy and AGN formation\nmodel, to generate the Uchuu-$\\nu^2$GC catalog, publicly available, that allows\nus to investigate the field-to-field variance of the luminosity function of\nAGN. With this Uchuu-$\\nu^2$GC model, we quantify the cosmic variance as a\nfunction of survey area, AGN luminosity, and redshift. In general, cosmic\nvariance decreases with increasing survey area and decreasing redshift. We find\nthat at $z\\sim6-7$, the cosmic variance depends weakly on AGN luminosity. This\nis because the typical mass of dark matter haloes in which AGN reside does not\nsignificantly depend on luminosity. Due to the rarity of AGN, Poisson variance\ndominates the total field-to-field variance, especially for bright AGN. We also\nexamine the effect of parameters related to galaxy formation physics on the\nfield variance. We discuss uncertainties present in the estimation of the\nfaint-end of the AGN luminosity function from recent observations, and extend\nthis to make predictions for the expected number of AGN and their variance for\nupcoming observations with Euclid, JWST, and the Legacy Survey of Space and\nTime (LSST).", "positive": "Constraints on the outer radius of the broad emission line region of\n active galactic nuclei: Here we present observational evidence that the broad emission line region\n(BELR) of active galactic nuclei (AGN) generally has an outer boundary. This\nwas already clear for sources with an obvious transition between the broad and\nnarrow components of their emission lines. We show that the narrow component of\nthe higher-order Paschen lines is absent in all sources, revealing a broad\nemission line profile with a broad, flat top. This indicates that the BELR is\nkinematically separate from the narrow emission line region. We use the virial\ntheorem to estimate the BELR outer radius from the flat top width of the\nunblended profiles of the strongest Paschen lines, Pa alpha and Pa beta, and\nfind that it scales with the ionising continuum luminosity roughly as expected\nfrom photoionisation theory. The value of the incident continuum photon flux\nresulting from this relationship corresponds to that required for dust\nsublimation. A flat-topped broad emission line profile is produced by both a\nspherical gas distribution in orbital motion as well as an accretion disc wind\nif the ratio between the BELR outer and inner radius is assumed to be less than\n~100 - 200. On the other hand, a pure Keplerian disc can be largely excluded,\nsince for most orientations and radial extents of the disc the emission line\nprofile is double-horned." }, { "anchor": "Are the Newly-Discovered $z \\sim 13$ Drop-out Sources Starburst Galaxies\n or Quasars?: The detection of two $z\\sim 13$ galaxy candidates has opened a new window on\ngalaxy formation at an era only $330$ Myr after the Big Bang. Here, we\ninvestigate the physical nature of these sources: are we witnessing star\nforming galaxies or quasars at such early epochs? If powered by star formation,\nthe observed ultraviolet (UV) luminosities and number densities can be jointly\nexplained if: (i) these galaxies are extreme star-formers with star formation\nrates $5-24\\times$ higher than those expected from extrapolations of average\nlower-redshift relations; (ii) the star formation efficiency increases with\nhalo mass and is countered by increasing dust attenuation from $z \\sim 10-5$;\n(iii) they form stars with an extremely top-heavy initial mass function. The\nquasar hypothesis is also plausible, with the UV luminosity produced by black\nholes of $\\sim 10^8 \\, \\mathrm{M_{\\odot}}$ accreting at or slightly above the\nEddington rate ($f_{\\rm Edd}\\sim 1.0$). This black hole mass at $z\\sim13$ would\nrequire very challenging, but not implausible, growth parameters. If\nspectroscopically confirmed, these two sources will represent a remarkable\nlaboratory to study the Universe at previously inaccessible redshifts.", "positive": "Mass loss rate of accretion disk in FRADO: We have developed the 2.5D version of the basic physically motivated 1D model\nof Czerny & Hryniewicz (2011), i.e. Failed Radiatively Accelerated Dusty\nOutflow (FRADO) model. This model is based on the idea that radiation pressure\nacting on dust is responsible for the formation of the low ionized part of the\nBroad Line Region (BLR). Such radiation pressure is strong enough to form a\nfast outflow from the disk surface in the inner part of low ionized BLR. The\noutflow properties depend on the basic physical parameters, like black hole\nmass, Eddington ratio and gas metallicity. We here aim at estimating the disk\nmass loss rate due to this process, and comparing the results with outflows\ndetected in Broad Absorption Line (BAL) quasars." }, { "anchor": "Update on 3D Moving Mesh Simulations of Galactic Center Cloud G2: Using three-dimensional, moving-mesh simulations, we investigate the future\nevolution of the recently discovered gas cloud G2 traveling through the\ngalactic center. From our simulations we expect an average feeding rate onto\nSgr A* in the range of $(5-19) \\times 10^{-8} M_\\odot\\mathrm{~yr}^{-1}$\nbeginning in 2014. This accretion varies by less than a factor of three on\ntimescales of about 1 month, and shows no more than a factor of 10 difference\nbetween the maximum and minimum observed rates within any given model. These\nrates are comparable to the current estimated accretion rate in the immediate\nvicinity of Sgr A*, although they represent only a small (<10%) increase over\nthe current expected feeding rate at the effective inner boundary of our\nsimulations $(r_\\mathrm{acc} = 750 R_S \\sim 10^{15} \\mathrm{cm})$. We also\nexplore multiple possible equations of state to describe the gas. In examining\nthe Br-$\\gamma$ light curves produced from our simulations, we find that all of\nour isothermal models predict significant (factor of 10) enhancements in the\nluminosity of G2 as it approaches pericenter, in conflict with observations.\nModels that instead allow the cloud to heat as it is compressed do better at\nmatching observations.", "positive": "JWST sneaks a peek at the stellar morphology of $z\\sim2$ submillimeter\n galaxies: Bulge formation at cosmic noon: We report morphological analyses of seven submillimeter galaxies (SMGs) at\n$z\\sim2$ using the JWST NIRCam images taken as part of the public CEERS and\nPRIMER surveys. Through two-dimensional surface brightness profile fittings we\nfind evidence of bulges in all the sample SMGs, in particular at F444W filter,\nsuggesting an ubiquitous presence of stellar bulges. The median size of these\nbulges at F444W is found to be 0.7$\\pm$1.0 kpc and its median Sersic index is\n0.7$\\pm$0.9. Structures akin to spiral arms and bars are also identified,\nalthough their asymmetric shapes, tidal features, as well as evidence of nearby\ngalaxies at consistent redshifts as those of corresponding SMGs suggest that\nthese SMGs are undergoing dynamical interactions, likely responsible for the\ntriggering of their star-forming activities. Via the curve-of-growth analyses\nwe deduce half-light radii for the NIRCam wavebands, finding that sizes are\nsignificantly smaller at longer wavelengths in all cases, in particular that\nthe median size ratio between F444W and F150W is $0.6\\pm0.1$. However, we also\nfind that F444W sizes, roughly corresponding to rest-frame $H$-band, are not\nsmaller than those of submillimeter continuum as measured by ALMA, contrasting\nrecent predictions from theoretical models. Our results suggest that while\nstellar bulges are undergoing an active formation phase in SMGs at $z\\sim2$,\nthe total stellar masses of SMGs are still dominated by their disks, not\nbulges." }, { "anchor": "Unveiling the formation route of the largest galaxies in the universe: Observational evidence indicates that the role of gas is secondary to that of\ngravity in the formation of the most luminous spheroids inhabiting the centres\nof galaxy associations, as originally conjectured in the late 80's/early 90's.\nHowever, attempts to explain the origin of the Fundamental Plane (FP) of\nmassive early-type galaxies (ETGs) -- a tilted version of the scaling relation\nconnecting the size, velocity dispersion and mass of virialized homologous\nsystems -- based on sequences of pairwise mergers, have systematically\nconcluded that dissipation cannot be ignored. We use controlled simulations of\nthe previrialization stage of galaxy groups to show that multiple collisionless\nmerging is capable of creating realistic first-ranked galaxies. Our mock\nremnants define a thin FP that perfectly fits data from all kinds of giant ETGs\nin the local volume, showing the existence of a unified relationship for these\nsystems. High-ranked galaxies occupy in the FP different areas than standard\nobjects, a segregation which is viewed essentially as zero-point offsets in the\n2D correlations arising from standard projections of this plane. Our findings\nmake a strong case for considering hierarchical dissipationless merging a\nviable route for the formation of the largest galaxies in the universe.", "positive": "Evidence for Populations-dependent vertical motions and the Long-lived\n Non-Steady Lopsided Milky Way Warp: We present the Galactic disk vertical velocity analysis using OB type stars\n(OB), Red Clump stars (RC), and Main-Sequence-Turn-Off stars (MSTO) with\ndifferent average age populations crossed matched with LAMOST DR5 and Gaia DR3.\nWe reveal the vertical velocities of the three populations varies clearly with\nthe Galactocentric distance ($R$) and the younger stellar population has\nstronger increasing trend in general. The bending and breathing modes indicated\nby the vertical motions are dependent on the populations and they are varying\nwith spatial locations. These vertical motions may be due to the Galactic warp,\nor minor mergers, or non-equilibrium of the disk. Assuming the warp is the\ndominant component, we find that the warp amplitude ($\\gamma$, $Z_\\omega$) for\nOB (younger population) is larger than that for RC (medium population) and the\nlater one is also larger than that for MSTO (older population), which is in\nagreement with other independent analyses of stellar density distribution, and\nsupports the warp is long-lived, non-steady structure and has time evolution.\nThis conclusion is robust whether or not the line-of-nodes $\\phi_w$ is fixed or\nas a free parameter (with $\\phi_w$ is around 3$-$8.5$^{\\circ}$ as best fit).\nFurthermore, we find that warp is lopsided with asymmetries along azimuthal\nangle ($\\phi$)." }, { "anchor": "ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Complex Organic\n and Deuterated Molecules: We have observed complex organic molecules (COMs) and deuterated species\ntoward a hot core/corino (HC) associated with the infrared dark cloud (IRDC)\nclump G34.43+00.24 MM3 with the Atacama Large Millimeter/submillimeter Array\n(ALMA). We have detected six normal-COMs (CH3OH, CH3CHO, CH3CH2CN, CH3OCH3,\nHCOOCH3, and NH2CHO), one deuterated-COM (CH2DCN), and two deuterated\nfundamental molecules (D2CO and DNC) toward G34.43+00.24 MM3 HC. None of these\nlines, except for CH3OH, are detected toward the shocked regions in our data,\nwhich suggests that COMs do not originate in shocks. The abundance of the COMs\nrelative to CH3OH in G34.43+00.24 MM3 HC is found to be similar to those in\nhigh-mass hot cores, rather than those in hot corinos in low-mass star-forming\nregions. This result suggests that the physical conditions of the warm-up phase\nof G34.43+00.24 MM3 HC are similar to those of high-mass sources. On the other\nhand, the D2CO abundance relative to CH$_3$OH in G34.43+00.24 MM3 HC is higher\nthan that of other hot cores, and seems to be comparable to that of hot\ncorinos. The relatively high D2CO/CH3OH ratio of G34.43+00.24 MM3 HC implies a\nlong cold starless phase of G34.43+00.24 MM3 HC.", "positive": "Hot Ammonia in the Center of the Seyfert 2 galaxy NGC 3079: We present the results of ammonia observations toward the center of NGC 3079.\nThe NH3(J, K) = (1, 1) and (2, 2) inversion lines were detected in absorption\nwith the Tsukuba 32-m telescope, and the NH3(1,1) through (6,6) lines with the\nVLA, although the profile of NH3(3,3) was in emission in contrast to the other\ntransitions. The background continuum source, whose flux density was ~50 mJy,\ncould not be resolved with the VLA beam of ~< 0.\"09 x 0.\"08. All ammonia\nabsorption lines have two distinct velocity components: one is at the systemic\nvelocity and the other is blueshifted, and both components are aligned along\nthe nuclear jets. For the systemic components, the relatively low temperature\ngas is extended more than the high temperature gas. The blueshifted NH3(3,3)\nemission can be regarded as ammonia masers associated with shocks by strong\nwinds probably from newly formed massive stars or supernova explosions in dense\nclouds in the nuclear megamaser disk. Using para-NH3(1,1), (2,2), (4,4) and\n(5,5) lines with VLA, we derived the rotational temperature Trot = 120 +- 12 K\nand 157 +- 19 K for the systemic and blueshifted components, respectively. The\ntotal column densities of NH3(0,0)-(6,6), assuming Tex ~Trot, were (8.85+-0.70)\nx 10^16 cm^-2 and (4.47+-0.78) x 10^16 cm-2 for the systemic and blueshifted\ncomponents, respectively. The fractional abundance of NH3 relative to molecular\nhydrogen H2 for the systemic and blueshifted was [NH3]/[H2]=1.3x10^-7 and 6.5 x\n10^-8, respectively. We also found the F = 4-4 and F = 5-5 doublet lines of OH\n2{Pi}3/2 J = 9/2 in absorption, which could be fitted by two velocity\ncomponents, systemic and redshifted components. The rotational temperature of\nOH was estimated to be Trot,OH >~ 175 K, tracing hot gas associated with the\ninteraction of the fast nuclear outflow with dense molecular material around\nthe nucleus." }, { "anchor": "Analysis of galaxy kinematics based on Cepheids from the Gaia DR2\n Catalogue: To construct the rotation curve of the Galaxy, classical Cepheids with proper\nmotions, parallaxes and line-of-sight velocities from the Gaia DR2 Catalog are\nused in large part. The working sample formed from literature data contains\nabout 800 Cepheids with estimates of their age. We determined that the linear\nrotation velocity of the Galaxy at a solar distance is $V_0=240\\pm3$~km\ns$^{-1}$. In this case, the distance from the Sun to the axis of rotation of\nthe Galaxy is found to be $R_0=8.27\\pm0.10$~kpc. A spectral analysis of radial\nand residual tangential velocities of Cepheids younger than 120 Myr showed\nclose estimates of the parameters of the spiral density wave obtained from data\nboth at present time and in the past. So, the value of the wavelength\n$\\lambda_{R,\\theta}$ is in the range of [2.4--3.0] kpc, the pitch angle\n$i_{R,\\theta}$ is in the range of [$-13^\\circ$,$-10^\\circ$] for a four-arm\npattern model, the amplitudes of the radial and tangential perturbations are\n$f_R\\sim12$~km s$^{-1}$ and $f_\\theta\\sim9$~km s$^{-1}$, respectively.\nVelocities of Cepheids older than 120 Myr are currently giving a wavelength\n$\\lambda_{R,\\theta}\\sim5$~kpc. This value differs significantly from one that\nwe obtained from the samples of young Cepheids. An analysis of positions and\nvelocities of old Cepheids, calculated by integrating their orbits backward in\ntime, made it possible to determine significantly more reliable values of the\nparameters of the spiral density wave: wavelength $\\lambda_{R,\\theta}=2.7$~kpc,\namplitudes of radial and tangential perturbations are $f_R=7.9$~km s$^{-1}$ and\n$f_\\theta=5$~km s$^{-1}$, respectively.", "positive": "How to inflate a wind-blown bubble: Stellar winds are one of several ways that massive stars can affect the star\nformation process on local and galactic scales. In this paper we investigate\nthe numerical resolution needed to inflate an energy-driven stellar wind bubble\nin an external medium. We find that the radius of the wind injection region,\n$r_{\\rm inj}$, must be below a maximum value, $r_{\\rm inj,max}$, in order for a\nbubble to be produced, but must be significantly below this value if the bubble\nproperties are to closely agree with analytical predictions. The final bubble\nmomentum is within 25 per cent of the value from a higher resolution reference\nmodel if $\\chi = r_{\\rm inj}/r_{\\rm inj,max}$ = 0.1. Our work has significance\nfor the amount of radial momentum that a wind-blown bubble can impart to the\nambient medium in simulations, and thus on the relative importance of stellar\nwind feedback." }, { "anchor": "The ALMA Fornax Cluster Survey I: stirring and stripping of the\n molecular gas in cluster galaxies: We present the first results of the ALMA Fornax Cluster Survey (AlFoCS): a\ncomplete ALMA survey of all members of the Fornax galaxy cluster that were\ndetected in HI or in the far infrared with Herschel. The sample consists of a\nwide variety of galaxy types, ranging from giant ellipticals to spiral galaxies\nand dwarfs, located in all (projected) areas of the cluster. It spans a mass\nrange of 10^(~8.5 - 11) M_Sun. The CO(1-0) line was targeted as a tracer for\nthe cold molecular gas, along with the associated 3 mm continuum. CO was\ndetected in 15 of the 30 galaxies observed. All 8 detected galaxies with\nstellar masses below 3x10^9 M_Sun have disturbed molecular gas reservoirs, only\n6 galaxies are regular/undisturbed. This implies that Fornax is still a very\nactive environment, having a significant impact on its members. Both detections\nand non-detections occur at all projected locations in the cluster. Based on\nvisual inspection, and the detection of molecular gas tails in alignment with\nthe direction of the cluster centre, in some cases ram pressure stripping is a\npossible candidate for disturbing the molecular gas morphologies and\nkinematics. Derived gas fractions in almost all galaxies are lower than\nexpected for field objects with the same mass, especially for the galaxies with\ndisturbed molecular gas, with differences of sometimes more than an order of\nmagnitude. The detection of these disturbed molecular gas reservoirs reveals\nthe importance of the cluster environment for even the tightly bound molecular\ngas phase.", "positive": "Stabilizing effect of magnetic helicity on magnetic cavities in the\n intergalactic medium: We investigate the effect of magnetic helicity on the stability of buoyant\nmagnetic cavities as found in the intergalactic medium. In these cavities, we\ninsert helical magnetic fields and test whether or not helicity can increase\ntheir stability to shredding through the Kelvin-Helmholtz instability and, with\nthat, their lifetime. This is compared to the case of an external vertical\nmagnetic field which is known to reduce the growth rate of the Kelvin-Helmholtz\ninstability. By comparing a low-helicity configuration with a high helicity one\nwith the same magnetic energy we find that an internal helical magnetic field\nstabilizes the cavity. This effect increases as we increase the helicity\ncontent. Stabilizing the cavity with an external magnetic field requires\ninstead a significantly stronger field at higher magnetic energy. We conclude\nthat the presence of helical magnetic fields is a viable mechanism to explain\nthe stability of intergalactic cavities on time scales longer than 100 Myr." }, { "anchor": "Structure Formation in Gas-Rich Galactic Discs with Finite Thickness:\n From Discs to Rings: Gravitational instabilities play an important role in structure formation of\ngas-rich high-redshift disc galaxies. In this paper, we revisit the\naxisymmetric perturbation theory and the resulting growth of structure by\ntaking the realistic thickness of the disc into account. In the unstable\nregime, which corresponds for thick discs to a Toomre parameter below the\ncritical value Q_0,crit = 0.696, we find a fastest growing perturbation\nwavelength that is always a factor 1.93 times larger than in the classical\nrazor-thin disc approximation. This result is independent of the adopted disc\nscaleheight and by this independent of temperature and surface density. In\norder to test the analytical theory, we compare it with a high-resolution\nhydrodynamical simulation of an isothermal gravitationally unstable gas disc\nwith the typical vertical sech^2 density profile and study its break up into\nrings that subsequently fragment into dense clumps. In the first phase, rings\nform, that organize themselves discretely, with distances corresponding to the\nlocal fastest growing perturbation wavelength. We find that the disc\nscaleheight has to be resolved initially with five or more grid cells in order\nto guarantee proper growth of the ring structures, which follow the analytical\nprediction. These rings later on contract to a thin and dense line, while at\nthe same time accreting more gas from the inter-ring region. It is these dense,\ncircular filaments, that subsequently fragment into a large number of clumps.\nContrary to what is typically assumed, the clump sizes are therefore not\ndirectly determined by the fastest growing wavelength.", "positive": "The origin of galactic metal-rich stellar halo components with highly\n eccentric orbits: Using the astrometry from the ESA's Gaia mission, previous works have shown\nthat the Milky Way stellar halo is dominated by metal-rich stars on highly\neccentric orbits. To shed light on the nature of this prominent halo component,\nwe have analysed 28 Galaxy analogues in the Auriga suite of cosmological\nhydrodynamics zoom-in simulations. Some three quarters of the Auriga galaxies\ncontain significant components with high radial velocity anisotropy, beta >\n0.6. However, only in one third of the hosts do the high-beta stars contribute\nsignificantly to the accreted stellar halo overall, similar to what is observed\nin the Milky Way. For this particular subset we reveal the origin of the\ndominant stellar halo component with high metallicity, [Fe/H]~-1, and high\norbital anisotropy, beta>0.8, by tracing their stars back to the epoch of\naccretion. It appears that, typically, these stars come from a single dwarf\ngalaxy with a stellar mass of order of 10^9-10^10 Msol that merged around 6-10\nGyr ago, causing a sharp increase in the halo mass. Our study therefore\nestablishes a firm link between the excess of radially anisotropic stellar\ndebris in the Milky Way halo and an ancient head-on collision between the young\nMilky Way and a massive dwarf galaxy" }, { "anchor": "Massive stars in massive clusters IV: Disruption of clouds by\n momentum-driven winds: We examine the effect of momentum-driven OB-star stellar winds on a parameter\nspace of simulated turbulent Giant Molecular Clouds using SPH hydrodynamical\nsimulations. By comparison with identical simulations in which ionizing\nradiation was included instead of winds, we show that momentum-driven winds are\nconsiderably less effective in disrupting their host clouds than are HII\nregions. The wind bubbles produced are smaller and generally smoother than the\ncorresponding ionization-driven bubbles. Winds are roughly as effective in\ndestroying the very dense gas in which the O-stars are embedded, and thus\nshutting down the main regions of star-forming activity in the model clouds.\nHowever, their influence falls off rapidly with distance from the sources, so\nthey are not as good at sweeping up dense gas and triggering star formation\nfurther out in the clouds. As a result, their effect on the star formation rate\nand efficiency is generally more negative than that of ionization, if they\nexert any effect at all.", "positive": "Total infrared luminosity estimation from local galaxies in AKARI all\n sky survey: We aim to use the a new and improved version of AKARI all sky survey\ncatalogue of far-infrared sources to recalibrate the formula to derive the\ntotal infrared luminosity. We cross-match the faint source catalogue (FSC) of\nIRAS with the new AKARI-FIS and obtained a sample of 2430 objects. Then we\ncalculate the total infrared (TIR) luminosity $L_{\\textrm{TIR}}$ from the\nSanders at al. (1996) formula and compare it with total infrared luminosity\nfrom AKARI FIS bands to obtain new coefficients for the general relation to\nconvert FIR luminosity from AKARI bands to the TIR luminosity." }, { "anchor": "The Chandra COSMOS Legacy Survey: clustering dependence of Type 2 AGN on\n host galaxy properties: Aims. We perform clustering measurements of 800 X-ray selected Chandra COSMOS\nLegacy (CCL) Type 2 AGN with known spectroscopic redshift to probe the halo\nmass dependence on AGN host galaxy properties, such as galaxy stellar mass\nMstar, star formation rate (SFR) and specific black hole accretion rate (BHAR),\nin the redshift range z = [0 - 3].\n Methods. We split the sample of AGN with known spectroscopic redshits\naccording to Mstar, SFR and specific BHAR, while matching the distributions in\nterms of the other parameters, including redshift. We measure the projected\ntwo-point correlation function wp(rp) and model it with the 2-halo term to\nderive the large-scale bias b and the corresponding typical mass of the hosting\nhalo, for the different subsamples.\n Results. We found no significant dependence of the large-scale bias and\ntypical halo mass on galaxy stellar mass and specific BHAR for CCL Type 2 AGN\nat mean z~1, while a negative dependence on SFR is observed, with lower SFR AGN\nresiding in richer environment. Mock catalogs of AGN matched to have the same\nX-ray luminosity, stellar mass, specific BHAR and SFR of CCL Type 2 AGN, almost\nreproduce the observed Mstar, specific BHAR and SFR-Mh relations, when assuming\na fraction of satellite AGN of 15%, which corresponds to a ratio between the\nprobabilities of satellite and central AGN of being active Q = 2. Mock matched\nnormal galaxies follow a slightly steeper Mstar -Mh relation with low mass mock\ngalaxies residing in less massive halos than mock AGN of similar mass, and are\nless biased than mock AGN with similar specific BHAR and SFR, at least for Q >\n1.", "positive": "A black hole detected in the young massive LMC cluster NGC 1850: We report the detection of a black hole (NGC 1850 BH1) in the $\\sim$100\nMyr-old massive cluster NGC~1850 in the Large Magellanic Cloud. It is in a\nbinary system with a main-sequence turn-off star (4.9 $\\pm$ 0.4 M${_\\odot}$),\nwhich is starting to fill its Roche Lobe and becoming distorted. Using 17\nepochs of VLT/MUSE observations we detected radial velocity variations\nexceeding 300 km/s associated to the target star, linked to the ellipsoidal\nvariations measured by OGLE-IV in the optical bands. Under the assumption of a\nsemi-detached system, the simultaneous modelling of radial velocity and light\ncurves constraints the orbital inclination of the binary to ($38 \\pm\n2$)$^{\\circ}$, resulting in a true mass of the unseen companion of\n$11.1_{-2.4}^{+2.1}$ $M_{\\odot}$. This represents the first direct dynamical\ndetection of a black hole in a young massive cluster, opening up the\npossibility of studying the initial mass function and the early dynamical\nevolution of such compact objects in high-density environments." }, { "anchor": "PhotoWeb redshift: boosting photometric redshift accuracy with large\n spectroscopic surveys: Improving distance measurements in large imaging surveys is a major challenge\nto better reveal the distribution of galaxies on a large scale and to link\ngalaxy properties with their environments. Photometric redshifts can be\nefficiently combined with the cosmic web (CW) extracted from overlapping\nspectroscopic surveys to improve their accuracy. We apply a similar method\nusing a new generation of photometric redshifts based on a convolution neural\nnetwork (CNN). The CNN is trained on the SDSS images with the main galaxy\nsample (SDSS-MGS, $r \\leq 17.8$) and the GAMA spectroscopic redshifts up tor\n$\\sim 19.8$. The mapping of the CW is obtained with 680,000 spectroscopic\nredshifts from the MGS and BOSS surveys. The redshift probability distribution\nfunctions (PDF), which are well calibrated (unbiased and narrow, $\\leq 120$\nMpc), intercept a few CW structure along the line of sight. Combining these\nPDFs with the density field distribution provides new photometric redshifts,\n$z_{web}$, whose accuracy is improved by a factor of two (i.e.,${\\sigma} \\sim\n0.004(1+z)$) for galaxies with $r \\leq 17.8$. For half of them, the distance\naccuracy is better than 10 cMpc. The narrower the original PDF, the larger the\nboost in accuracy. No gain is observed for original PDFs wider than 0.03. The\nfinal $z_{web}$ PDFs also appear well calibrated. The method performs slightly\nbetter for passive galaxies than star-forming ones, and for galaxies in massive\ngroups since these populations better trace the underlying large-scale\nstructure. Reducing the spectroscopic sampling by a factor of 8 still improves\nthe photometric redshift accuracy by 25%. Extending the method to galaxies\nfainter than the MGS limit still improves the redshift estimates for 70% of the\ngalaxies, with a gain in accuracy of 20% at low $z$ where the resolution of the\nCW is the highest.", "positive": "Obscured accretion from AGN surveys: Recent models of super-massive black hole (SMBH) and host galaxy joint\nevolution predict the presence of a key phase where accretion, traced by\nobscured Active Galactic Nuclei (AGN) emission, is coupled with powerful star\nformation. Then feedback processes likely self-regulate the SMBH growth and\nquench the star-formation activity. AGN in this important evolutionary phase\nhave been revealed in the last decade via surveys at different wavelengths. On\nthe one hand, moderate-to-deep X-ray surveys have allowed a systematic search\nfor heavily obscured AGN, up to very high redshifts (z~5). On the other hand,\ninfrared/optical surveys have been invaluable in offering complementary methods\nto select obscured AGN also in cases where the nuclear X-ray emission below 10\nkeV is largely hidden to our view. In this review I will present my personal\nperspective of the field of obscured accretion from AGN surveys." }, { "anchor": "Optical observations of the nearby galaxy IC342 with narrow band [SII]\n and H$\u03b1$ filters. II - Detection of 16 Optically-Identified Supernova\n Remnant Candidates: We present the detection of 16 optical supernova remnant (SNR) candidates in\nthe nearby spiral galaxy IC342. The candidates were detected by applying\n[SII]/H$\\alpha$ ratio criterion on observations made with the 2 m RCC telescope\nat Rozhen National Astronomical Observatory in Bulgaria. In this paper, we\nreport the coordinates, diameters, H$\\alpha$ and [SII] fluxes for 16 SNRs\ndetected in two fields of view in the IC342 galaxy. Also, we estimate that the\ncontamination of total H$\\alpha$ flux from SNRs in the observed portion of\nIC342 is 1.4%. This would represent the fractional error when the star\nformation rate (SFR) for this galaxy is derived from the total galaxy's\nH$\\alpha$ emission.", "positive": "Deep optical imaging of star-forming blue early-type galaxies: Color map\n structures and faint features indicative of recent mergers: Blue early-type galaxies with galaxy-scale ongoing star formation are\ninteresting targets in order to understand the stellar mass buildup in\nelliptical and S0 galaxies in the local Universe. We study the star-forming\npopulation of blue early-type galaxies to understand the origin of star\nformation in these otherwise red and dead stellar systems. The legacy survey\nimaging data taken with the dark energy camera in the $g$, $r$, and $z$ bands\nfor 55 star-forming blue early-type galaxies were examined, and $g-r$ color\nmaps were created. We identified low surface brightness features near 37\ngalaxies, faint-level interaction signatures near 15 galaxies, and structures\nindicative of recent merger activity in the optical color maps of all 55\ngalaxies. These features are not visible in the shallow Sloan Digital Sky\nSurvey imaging data in which these galaxies were originally identified. Low\nsurface brightness features found around galaxies could be remnants of recent\nmerger events. The star-forming population of blue early-type galaxies could be\npost-merger systems that are expected to be the pathway for the formation of\nelliptical galaxies. We hypothesize that the star-forming population of blue\nearly-type galaxies is a stage in the evolution of early-type galaxies. The\nmerger features will eventually disappear, fuel for star formation will cease,\nand the galaxy will move to the passive population of normal early-type\ngalaxies." }, { "anchor": "Phase Wrapping of Epicyclic Perturbations in the Wobbly Galaxy: We use test-particle integrations to show that epicyclic motions excited by a\npericentre passage of a dwarf galaxy could account for bulk vertical velocity\nstreaming motions recently observed in the Galactic stellar disc near the Sun.\nWe use fixed potential test-particle integrations to isolate the role of phase\nwrapping of epicyclic perturbations from bending and breathing waves or modes,\nwhich require self-gravity to oscillate. Perturbations from a fairly massive\nSagittarius dwarf galaxy, $M_d \\sim 2.5 \\times 10^{10} M_\\odot$, are required\nto account for the size of the observed streaming motions from its orbital\npericentre approximately a Gyr ago. A previous passage of the dwarf through the\nGalactic disc approximately 2.2 Gyr ago (with a then more massive dwarf galaxy)\nis less effective. If phase wrapping of epicyclic perturbations is responsible\nfor stellar streaming motions in the Galactic disc, then there should be\nvariations in velocity gradients on scales of a few kpc in the vicinity of the\nSun.", "positive": "Multiwavelength Study of Dark Globule DC 314.8-5.1: Point Source\n Identification and Diffuse Emission Characterization: We present an analysis of multi-wavelength observations of the dark globule\nDC\\,314.8--5.1, using data from the Gaia optical, 2MASS near-infrared, and WISE\nmid-infrared surveys, dedicated imaging with the Spitzer Space Telescope, and\nX-ray data obtained with the Swift-XRT Telescope (XRT). The main goal was to\nidentify possible pre-main sequence stars (PMSs) and young stellar objects\n(YSOs) associated with the globule. For this, we studied the infrared colors of\nall point sources within the boundaries of the cloud. After removing sources\nwith non-stellar spectra, we investigated the Gaia parallaxes for the YSO\ncandidates, and found that none are physically related to DC\\,314.8--5.1. In\naddition, we searched for X-ray emission from pre-main sequence stars with\nSwift-XRT, and found no 0.5--10\\,keV emission down to a luminosity level\n$\\lesssim 10^{31}$erg\\,s$^{-1}$, typical of a PMS with mass\\,$\\ge 2 M_\\odot$.\nOur detailed inspection therefore supports a very young, ``pre-stellar core''\nevolutionary stage for the cloud. Based on archival Planck and IRAS data, we\nmoreover identify the presence of hot dust, with temperatures $\\gtrsim 100$\\,K,\nin addition to the dominant dust component at 14\\,K, originating with the\nassociated reflection nebula." }, { "anchor": "A tentative $\\sim$1000 km s$^{-1}$ offset between the [CII] 158 $\u03bc$m\n and Ly$\u03b1$ line emission in a star-forming galaxy at $z = 7.2$: GN-108036 is a star-forming galaxy at $z=7.21$, and one of the most distant\nknown sources in the Northern hemisphere. Based on observations from the\nNOrthern Extended Millimeter Array (NOEMA), here we report the tentative\ndetection of the [CII] line at $\\approx4\\sigma$ significance. The integrated\n[CII] line emission is spatially offset about $\\sim4$ kpc from the rest-frame\nultraviolet (UV) emission. The total [CII] luminosity ($L_{\\rm\n[CII]}=2.7\\times10^8~L_{\\odot}$) is consistent with the relation between [CII]\nluminosity and star formation rate (SFR) observed in nearby and high-$z$ star\nforming galaxies. More interestingly, the [CII] line is blueshifted with\nrespect to the Ly$\\alpha$ line by $980\\pm10$ km s$^{-1}$. If confirmed, this\ncorresponds to the largest velocity offset reported to date between the\nLy$\\alpha$ line and a non-resonant line at $z\\gtrsim6$. According to trends\nobserved in other high redshift galaxies, the large Ly$\\alpha$ velocity offset\nin GN-108036 is consistent with its low Ly$\\alpha$ equivalent width and high UV\nabsolute magnitude. Based on Ly$\\alpha$ radiative transfer models of expanding\nshells, the large Ly$\\alpha$ velocity offset in GN-108036 could be interpreted\nas the presence of a large column density of hydrogen gas, and/or an outflow\nwith a velocity of $v_{\\rm out}\\sim\\Delta v_{\\rm Ly \\alpha}/2\\sim500$ km\ns$^{-1}$. We also report the 3$\\sigma$ detection of a potential galaxy\ncompanion located $\\sim30$ kpc east of GN-108036, at a similar systemic\nvelocity, and with no counterpart rest-frame UV emission.", "positive": "Giant radio galaxies in the LOFAR Two-metre Sky Survey-I: Giant radio galaxies (GRGs) are a subclass of radio galaxies which have grown\nto megaparsec scales. GRGs are much rarer than normal sized radio galaxies (<\n0.7 Mpc) and the reason for their gigantic sizes is still debated. Here, we\nreport the biggest sample of GRGs identified to date. These objects were found\nin the LOFAR Two-metre Sky Survey (LoTSS) first data release images, which\ncover a 424 square degrees region. Of the 239 GRGs found, 225 are new\ndiscoveries. The GRGs in our sample have sizes ranging from 0.7 to 3.5 Mpc and\nhave redshifts (z) between 0.1 and 2.3. Seven GRGs have sizes above 2 Mpc and\none has a size of ~ 3.5 Mpc. The sample contains 40 GRGs hosted by\nspectroscopically confirmed quasars. Here, we present the search techniques\nemployed and the resulting catalogue of the newly discovered large sample of\nGRGs along with their radio properties. We, here also show for the first time\nthat the spectral index of GRGs is similar to that of normal sized radio\ngalaxies, indicating that most of the GRG population is not dead or is not like\nremnant type radio galaxy. We find 20/239 GRGs in our sample are located at the\ncentres of clusters and present our analysis on their cluster environment and\nradio morphology." }, { "anchor": "Radio spectral properties of cores and extended regions in blazars in\n the MHz regime: Low-frequency radio surveys allow in-depth studies and new analyses of\nclasses of sources previously known and characterised only in other bands. In\nrecent years, low radio frequency observations of blazars have been available\nthanks to new surveys, such as the GaLactic and Extragalactic All-sky MWA\nSurvey (GLEAM). We search for gamma-ray blazars in a low frequency (${\\nu}$ <\n240MHz) survey, to characterise the spectral properties of the spatial\ncomponents. We cross-correlate GLEAM with the fourth catalogue of active\ngalactic nuclei (4LAC) detected by the Fermi satellite. This improves over\nprevious works using a low frequency catalogue that is wider, deeper, with a\nbetter spectral coverage and the latest and most sensitive gamma-ray source\nlist. In comparison to the previous study based on the commissioning survey,\nthe detection rate increased from 35% to 70%. We include Australia Telescope\n20GHz (AT20G) Survey data to extract high-frequency high-angular resolution\ninformation on the radio cores of blazars. We find low radio frequency\ncounterparts for 1274 out of 1827 blazars in the 72-231 MHz range. Blazars have\nat spectrum at $\\sim$ 100MHz regime, with a mean spectral index ${\\alpha}$ =\n-0.44 +-0.01 (assuming S $\\propto$ ${\\nu}^ {\\alpha}$ ). Low synchrotron peaked\nobjects have a scatter spectrum than high synchrotron peaked objects. Low\nfrequency radio and gamma-ray emission show a significant but scattered\ncorrelation. The ratio between lobe and core radio emission in gamma-ray\nblazars is smaller than previously estimated.", "positive": "Chemical Analysis of a Diffuse Cloud along a Line of Sight Toward W51:\n Molecular Fraction and Cosmic-Ray Ionization Rate: Absorption lines from the molecules OH+, H2O+, and H3+ have been observed in\na diffuse molecular cloud along a line of sight near W51 IRS2. We present the\nfirst chemical analysis that combines the information provided by all three of\nthese species. Together, OH+ and H2O+ are used to determine the molecular\nhydrogen fraction in the outskirts of the observed cloud, as well as the\ncosmic-ray ionization rate of atomic hydrogen. H3+ is used to infer the\ncosmic-ray ionization rate of H2 in the molecular interior of the cloud, which\nwe find to be zeta_2=(4.8+-3.4)x10^-16 per second. Combining the results from\nall three species we find an efficiency factor---defined as the ratio of the\nformation rate of OH+ to the cosmic-ray ionization rate of H---of\nepsilon=0.07+-0.04, much lower than predicted by chemical models. This is an\nimportant step in the future use of OH+ and H2O+ on their own as tracers of the\ncosmic-ray ionization rate." }, { "anchor": "Simulating galactic outflows with thermal supernova feedback: Cosmological simulations make use of sub-grid recipes for the implementation\nof galactic winds driven by massive stars because direct injection of supernova\nenergy in thermal form leads to strong radiative losses, rendering the feedback\ninefficient. We argue that the main cause of the catastrophic cooling is a\nmismatch between the mass of the gas in which the energy is injected and the\nmass of the parent stellar population. Because too much mass is heated, the\ntemperatures are too low and the cooling times too short. We use analytic\narguments to estimate, as a function of the gas density and the numerical\nresolution, the minimum heating temperature that is required for the injected\nthermal energy to be efficiently converted into kinetic energy. We then propose\nand test a stochastic implementation of thermal feedback that uses this minimum\ntemperature increase as an input parameter and that can be employed in both\nparticle- and grid-based codes. We use smoothed particle hydrodynamics\nsimulations to test the method on models of isolated disc galaxies in dark\nmatter haloes with total mass 10^10 and 10^12 h^-1 solar masses. The thermal\nfeedback strongly suppresses the star formation rate and can drive massive,\nlarge-scale outflows without the need to turn off radiative cooling\ntemporarily. In accord with expectations derived from analytic arguments, for\nsufficiently high resolution the results become insensitive to the imposed\ntemperature jump and also agree with high-resolution simulations employing\nkinetic feedback.", "positive": "Chemical Cartography with APOGEE: Large-scale Mean Metallicity Maps of\n the Milky Way: We present Galactic mean metallicity maps derived from the first year of the\nSDSS-III APOGEE experiment. Mean abundances in different zones of\nGalactocentric radius (0 < R < 15 kpc) at a range of heights above the plane (0\n< |z| < 3 kpc), are derived from a sample of nearly 20,000 stars with\nunprecedented coverage, including stars in the Galactic mid-plane at large\ndistances. We also split the sample into subsamples of stars with low and\nhigh-[{\\alpha}/M] abundance ratios. We assess possible biases in deriving the\nmean abundances, and find they are likely to be small except in the inner\nregions of the Galaxy. A negative radial gradient exists over much of the\nGalaxy; however, the gradient appears to flatten for R < 6 kpc, in particular\nnear the Galactic mid-plane and for low-[{\\alpha}/M] stars. At R > 6 kpc, the\ngradient flattens as one moves off of the plane, and is flatter at all heights\nfor high-[{\\alpha}/M] stars than for low-[{\\alpha}/M] stars. Alternatively,\nthese gradients can be described as vertical gradients that flatten at larger\nGalactocentric radius; these vertical gradients are similar for both low and\nhigh-[{\\alpha}/M] populations. Stars with higher [{\\alpha}/M] appear to have a\nflatter radial gradient than stars with lower [{\\alpha}/M]. This could suggest\nthat the metallicity gradient has grown steeper with time or, alternatively,\nthat gradients are washed out over time by migration of stars." }, { "anchor": "Local Active Galactic Nuclei with Large Broad-H\u03b1 Variability\n Reside in Red Galaxies: Inspired by our serendipitous discovery of six AGNs with varying broad-Halpha\nfluxes over years out of our searching for intermediate-mass black holes\n(IMBHs), we conduct a systematic investigation of changing-look (CL) and\nlarge-variability AGNs. We collect all the CL AGNs at z<0.15 and the\nreverberation mapped AGNs with strongly variable broad Halpha, and perform\ncareful decomposition fittings to both their images and spectra. We find two\nobservational facts: (1) The host galaxies of local CL and large-variability\nAGNs, mainly being Seyferts, are in the red (gas-poor) tail of the general\nSeyfert galaxy population. (2) In contrast, there is a significant trend that\ntheir more luminous counterparts namely CL and extremely variable quasars (CLQs\nand EVQs) are different: CLQs are generally in blue galaxies; in terms of the\ndiagram of SFR and M* local CL Seyfert galaxies are located in the green\nvalley, whereas CLQ hosts are in the star-forming main sequence. We propose\nexplanations for those strongly variable Seyferts and quasars, respectively,\nunder the thought that accretion disks broadly depend on nuclear fueling modes.\nLocal large-variability and CL Seyferts are in nuclear famine mode, where\ncold-gas clumps can be formed stochastically in the fueling flow, and their\nepisodic infall produces sharp peaks in the accretion-rate curve. CLQs and EVQs\nare in feast fueling mode, which may account for both their preference to blue\ngalaxies and their variability pattern (high-amplitude tail of the continuous\ndistribution). Lastly, we propose a new thinking: to search for IMBHs by\noptical variability in red galaxies.", "positive": "The effect of multilayer ice chemistry on gas-phase deuteration in\n starless cores: Aims. We aim to investigate whether a multilayer ice model can be as\nsuccessful as a bulk ice model in reproducing the observed abundances of\nvarious deuterated gas-phase species toward starless cores. Methods. We\ncalculate abundances for various deuterated species as functions of time\nadopting fixed physical conditions. We also estimate abundance gradients by\nadopting a modified Bonnor-Ebert sphere as a core model. In the multilayer ice\nscenario, we consider desorption from one or several monolayers on the surface.\nResults. We find that the multilayer model predicts abundances of $\\rm DCO^+$\nand $\\rm N_2D^+$ that are about an order of magnitude lower than observed,\ncaused by the trapping of CO and $\\rm N_2$ into the grain mantle. As a result\nof the mantle trapping, deuteration efficiency in the gas phase increases and\nwe find stronger deuterium fractionation in ammonia than what has been\nobserved. Another distinguishing feature of the multilayer model is that $\\rm\nD_3^+$ becomes the main deuterated ion at high density. The bulk ice model is\ngenerally easily reconciled with observations. Conclusions. Our results\nunderline that more theoretical and experimental work is needed to understand\nthe composition and morphology of interstellar ices, and the desorption\nprocesses that can act on them. With the current constraints, the bulk ice\nmodel appears to be better in reproducing observations than the multilayer ice\nmodel. According to our results, the $\\rm H_2D^+$ to $\\rm N_2D^+$ abundance\nratio is higher than 100 in the multilayer model, while only a few $\\times$ 10\nin the bulk model, and so observations of this ratio could provide information\non the ice morphology in starless cores. Observations of the abundance of $\\rm\nD_3^+$ compared to $\\rm H_2D^+$ and $\\rm D_2H^+$ would provide additional\nconstraints for the models." }, { "anchor": "Metal-poor, Strongly Star-Forming Galaxies in the DEEP2 Survey: The\n Relationship between Stellar Mass, Temperature-based Metallicity, and Star\n Formation Rate: We report on the discovery of 28 $z\\approx0.8$ metal-poor galaxies in DEEP2.\nThese galaxies were selected for their detection of the weak\n[OIII]$\\lambda$4363 emission line, which provides a \"direct\" measure of the\ngas-phase metallicity. A primary goal for identifying these rare galaxies is to\nexamine whether the fundamental metallicity relation (FMR) between stellar\nmass, gas metallicity, and star formation rate (SFR) holds for low stellar mass\nand high SFR galaxies. The FMR suggests that higher SFR galaxies have lower\nmetallicity (at fixed stellar mass). To test this trend, we combine\nspectroscopic measurements of metallicity and dust-corrected SFRs, with stellar\nmass estimates from modeling the optical photometry. We find that these\ngalaxies are $1.05\\pm0.61$ dex above the z~1 stellar mass-SFR relation, and\n$0.23\\pm0.23$ dex below the local mass-metallicity relation. Relative to the\nFMR, the latter offset is reduced to 0.01 dex, but significant dispersion\nremains (0.29 dex with 0.16 dex due to measurement uncertainties). This\ndispersion suggests that gas accretion, star formation and chemical enrichment\nhave not reached equilibrium in these galaxies. This is evident by their short\nstellar mass doubling timescale of $\\approx100^{+310}_{-75}$ Myr that suggests\nstochastic star formation. Combining our sample with other z~1 metal-poor\ngalaxies, we find a weak positive SFR-metallicity dependence (at fixed stellar\nmass) that is significant at 94.4% confidence. We interpret this positive\ncorrelation as recent star formation that has enriched the gas, but has not had\ntime to drive the metal-enriched gas out with feedback mechanisms.", "positive": "History and modes of star formation in the most active region of the\n Small Magellanic Cloud, NGC 346: We discuss the star formation history of the SMC region NGC 346 based on\nHubble Space Telescope images. The region contains both field stars and cluster\nmembers. Using a classical synthetic CMD procedure applied to the field around\nNGC 346 we find that there the star formation pace has been rising from a quite\nlow rate 13 Gyr ago to \\approx 1.4 \\times 10^{-8} Mo yr^{-1}pc^{-2} in the last\n100 Myr. This value is significantly higher than in other star forming regions\nof the SMC. For NGC 346 itself, we compare theoretical and observed\nColor-Magnitude Diagrams (CMDs) of several stellar sub-clusters identified in\nthe region, and we derive their basic evolution parameters. We find that NGC\n346 experienced different star formation regimes, including a dominant and\nfocused \"high density mode\", with the sub-clusters hosting both pre-main\nsequence (PMS) and upper main sequence (UMS) stars, and a diffuse \"low density\nmode\", as indicated by the presence of low-mass PMS sub-clusters.\nQuantitatively, the star formation in the oldest sub-clusters started about 6\nMyr ago with remarkable synchronization, it continued at high rate (up to 2\n\\times 10^{-5} Mo yr^{-1} pc^{-2}) for about 3 Myr and is now progressing at a\nlower rate. Interestingly, sub-clusters mainly composed by low mass PMS stars\nseem to experience now the first episode of star formation, following\nmulti-seeded spatial patterns instead of resulting from a coherent trigger. Two\nspeculative scenarios are put forth to explain the deficiency of UMS stars: the\nfirst invokes under-threshold conditions of the parent gas; the second\nspeculates that the initial mass function (IMF) is a function of time, with the\nyoungest sub-clusters not having had sufficient time to form more massive\nstars." }, { "anchor": "Isolated Galaxies versus Interacting Pairs with MaNGA: We present preliminary results of the spectral analysis on the radial\ndistributions of the star formation history in both, a galaxy merger and a\nspiral isolated galaxy observed with MaNGA. We find that the central part of\nthe isolated galaxy is composed by older stellar population ($\\sim$2 Gyr) than\nin the outskirts ($\\sim$7 Gyr). Also, the time-scale is gradually larger from 1\nGyr in the inner part to 3 Gyr in the outer regions of the galaxy. In the case\nof the merger, the stellar population in the central region is older than in\nthe tails, presenting a longer time-scale in comparison to central part in the\nisolated galaxy. Our results are in agreement with a scenario where spiral\ngalaxies are built from inside-out. In the case of the merger, we find evidence\nthat interactions enhance star formation in the central part of the galaxy.", "positive": "Nobeyama 45m Cygnus-X CO survey I: photodissociation of molecules\n revealed by the unbiased large-scale CN and C$^{18}$O maps: We present an unbiased large-scale (9 deg$^2$) CN ($N$=1-0) and C$^{18}$O\n($J$=1-0) survey of Cygnus-X conducted with the Nobeyama 45m Cygnus-X CO\nsurvey. CN and C$^{18}$O are detected in various objects towards the Cygnus-X\nNorth and South (e.g., DR17, DR18, DR21, DR22, DR23, and W75N). We find that\nCN/C$^{18}$O integrated intensity ratios are systematically different from\nregion to region, and are especially enhanced in DR17 and DR18 which are\nirradiated by the nearby OB stars. This result suggests that CN/C$^{18}$O\nratios are enhanced via photodissociation reactions. We investigate the\nrelation between the CN/C$^{18}$O ratio and strength of the UV radiation field.\nAs a result, we find that CN/C$^{18}$O ratios correlate with the far-UV\nintensities, $G_0$. We also find that CN/C$^{18}$O ratios decrease inside\nmolecular clouds, where the interstellar UV radiation is reduced due to the\ninterstellar dust extinction. We conclude that the CN/C$^{18}$O ratio is\ncontrolled by the UV radiation, and is a good probe of photon-dominated\nregions." }, { "anchor": "Self-Sealing Shells: Blowouts and Blisters on the Surfaces of Leaky\n Wind-Blown-Bubbles and Supernova Remnants: Blowouts can occur when a dense shell confining hot, high pressure, gas\nruptures. The venting gas inflates a blister on the surface of the shell. Here\nwe examine the growth of such blisters on the surfaces of wind-blown-bubbles\n(WBBs) and supernova remnants (SNRs) due to shell rupture caused by the\nVishniac instability. On WBBs the maximum relative size of the blister\n(R_bstall/R) is found to grow linearly with time, but in many cases the blister\nradius will not exceed 20 per cent of the bubble radius. Thus blowouts\ninitiated by the Vishniac instability are unlikely to have a major effect on\nthe global dynamics and properties of the bubble. The relative size of blisters\non SNRs is even smaller than on WBBs, with blisters only growing to a radius\ncomparable to the thickness of the cold shell of SNRs. The small size of the\nSNR blowouts is, however, in good agreement with observations of blisters in\nthe Vela SNR. The difference in relative size between WBB and SNR blisters is\ndue to the much higher speed at which gas vents out of WBBs, which translates\ninto a greater energy flux through a rupture of a given size from interior gas\nof a given pressure. Larger blisters are possible if shell ruptures are bigger\nthan expected.\n We expect the observed velocity structure of SNR shells to be affected by the\npresence of blisters until the shell is no longer susceptible to ruptures,\nsince the initial expansion of blisters is faster than the ongoing expansion of\nthe shell.", "positive": "J-PLUS: A wide-field multi-band study of the M15 globular cluster.\n Evidence of multiple stellar populations in the RGB: The Javalambre Photometric Local Universe Survey (J-PLUS) provides wide\nfield-of-view images in 12 narrow, intermediate and broad-band filters\noptimized for stellar photometry. Here we have applied J-PLUS data for the\nfirst time for the study of Galactic GCs using science verification data\nobtained for the very metal-poor GC M\\,15. Our J-PLUS data provide\nlow-resolution spectral energy distributions covering the near-UV to the\nnear-IR, allowing us to search for MPs based on pseudo-spectral fitting\ndiagnostics. J-PLUS CMDs are found to be particularly useful to search for\nsplits in the sequences formed by the upper red giant branch (RGB) and\nasymptotic giant branch (AGB) stars. We interpret these split sequences as\nevidence for the presence of MPs. This demonstrates that the J-PLUS survey will\nhave sufficient spatial coverage and spectral resolution to perform a large\nstatistical study of GCs through multi-band photometry in the coming years." }, { "anchor": "Galactic Isotopic Decomposition for the Sculptor Dwarf Spheroidal Galaxy: Stellar evolution models require initial isotopic abundance sets as input,\nbut these abundances are incomplete outside the solar neighborhood, are\nchallenging to infer from elemental observations, and are galaxy specific.\nCompositions different from the Milky Way (MW) have distinct chemical histories\nand are important to explore. We present an isotopic history model for the\nSculptor dwarf spheroidal galaxy (dSph) based on astrophysical processes, using\na complementary approach to GCE models, which can estimate isotopic abundances\nfor future nucleosynthesis studies. We approximated the isotopic composition of\nSculptor's late stage evolution using the OMEGA chemical evolution code and\nused Big Bang Nucleosynthesis (BBN) predictions as the other boundary\ncondition. Isotopic abundances were scaled from late stage evolution to BBN\nvalues according to the astrophysical processes responsible for their\nproduction. The isotopic abundances were summed into elemental abundances and\nfit to observational Sculptor abundance data to tune the free parameters. The\ncompleted model gives the average isotopic history of Sculptor for massive\nstar, Type Ia SNe, main $s$-process peak, and $r$-process contributions. We\nfind that Type Ia SNe contribute $\\approx$ 86 per cent to the late stage\nevolution Fe abundance, which agrees with other dSph chemical evolution\nstudies, and is greater than typical MW values of $\\approx$ 70 per cent found\nusing a similar process. The model also finds that neutron star mergers\ncontribute $\\approx$ 30 per cent to the late stage evolution Eu abundance,\nsuggesting that CCSNe may be the dominant $r$-process progenitors in dSphs.", "positive": "Starburst Driven Galactic Superbubbles Radiating to 10 K: Our three-dimensional hydro-dynamical simulations of starbursts examine the\nformation of superbubbles over a range of driving luminosities and mass\nloadings that determine superbubble growth and wind velocity. From this we\ndetermine the relationship between the velocity of a galactic wind and the\npower of the starburst. We find a threshold for the formation of a wind, above\nwhich the speed of the wind is not affected by grid resolution or the\ntemperature floor of our radiative cooling. We investigate the effect two\ndifferent temperature floors in our radiative cooling prescription have on wind\nkinematics and content. We find that cooling to $10$ K instead of to $10^4$ K\nincreases the mass fraction of cold neutral and hot X-ray gas in the galactic\nwind while halving that in warm H$\\alpha$. Our simulations show the mass of\ncold gas transported into the lower halo does not depend on the starburst\nstrength. Optically bright filaments form at the edge of merging superbubbles,\nor where a cold dense cloud has been disrupted by the wind. Filaments formed by\nmerging superbubbles will persist and grow to $>400$ pc in length if anchored\nto a star forming complex. Filaments embedded in the hot galactic wind contain\nwarm and cold gas that moves $300-1200$ km s$^{-1}$ slower than the surrounding\nwind, with the coldest gas hardly moving with respect to the galaxy. Warm and\ncold matter in the galactic wind show asymmetric absorption profiles consistent\nwith observations, with a thin tail up to the wind velocity." }, { "anchor": "A lower limit to the accretion disc radius in the low-luminosity AGN NGC\n 1052 derived from high-angular resolution data: We investigate the central sub-arcsec region of the low-luminosity active\ngalactic nucleus NGC 1052, using a high-angular resolution dataset that covers\n10 orders of magnitude in frequency. This allows us to infer the continuum\nemission within the innermost $\\sim {17}\\,$pc around the black hole to be of\nnon-thermal, synchrotron origin and to set a limit to the maximum contribution\nof a standard accretion disc. Assuming the canonical 10 per cent mass-light\nconversion efficiency for the standard accretion disc, its inferred accretion\npower would be too low by one order of magnitude to account for the observed\ncontinuum luminosity. We thus introduce a truncated accretion disc and derive a\ntruncation radius to mass-light conversion efficiency relation, which we use to\nreconcile the inferred accretion power with the continuum luminosity. As a\nresult we find that a truncated disc providing the necessary accretion power\nmust be truncated at $r_\\text{tr} \\gtrsim {26}\\, r_\\text{g}$, consistent with\nthe inner radius derived from the observations of the Fe K$\\alpha$ line in the\nX-ray spectrum of this nucleus. This is the first time to derive a limit on the\ntruncation radius of the accretion disc from high-angular resolution data only.", "positive": "Possible Solution of the long-standing discrepancy in the Microlensing\n Optical Depth Toward the Galactic Bulge by correcting the stellar number\n count: We find that significant incompleteness in stellar number counts results in a\nsignificant overestimate of the microlensing optical depth $\\tau$ and event\nrate per star per year $\\Gamma$ toward the Galactic bulge from the first two\nyears of the MOA-II survey. We find that the completeness in Red Clump Giant\n(RCG) counts $f_{\\rm RC}$ decreases proportional to the galactic latitude $b$,\nas $f_{\\rm RC}=(0.63\\pm0.11)-(0.052\\pm0.028)\\times b$, ranging between 1 and\n0.7 at $b=-6^\\circ\\sim-1.5^\\circ$. The previous measurements using all sources\nby Difference Image Analysis (DIA) by MACHO and MOA-I suffer the same bias. On\nthe other hand, the measurements using a RCG sample by OGLE-II, MACHO and EROS\nwere free from this bias because they selected only the events associated with\nthe resolved stars. Thus, the incompleteness both in the number of events and\nstellar number count cancel out. We estimate $\\tau$ and $\\Gamma$ by correcting\nthis incompleteness. In the central fields with $|l|<5^\\circ$, we find\n$\\Gamma=[18.74\\pm0.91]\\times10^{-6}\\exp[(0.53\\pm0.05)(3-|b|)]$ star$^{-1}$\nyr$^{-1}$ and $\\tau_{200}=[1.84\\pm0.14]\\times10^{-6}\\exp[(0.44\\pm0.07)(3-|b|)]$\nfor the 427 events with $t_{\\rm E}\\leq200\\,$days using all sources brighter\nthan $I_s\\leq20$ mag. Our revised all-source $\\tau$ measurements are about\n2-$\\sigma$ smaller than the other all-source measurements and are consistent\nwith the RCG measurements within 1-$\\sigma$. We conclude that the long-standing\nproblem on discrepancy between the high $\\tau$ with all-source samples by DIA\nand low $\\tau$ with RCG samples can probably be explained by the incompleteness\nof the stellar number count. A model fit to these measurements predicts\n$\\Gamma=4.60\\pm0.25\\times10^{-5}$ star$^{-1}$ yr$^{-1}$ at $|b|\\sim-1^\\circ.4$\nand $-2^\\circ.25 3 x 10^{10} M_sun and specific star formation rates\nsSFR < 10^{-11} yr^{-1} emerge at z~4.2 in TNG300. Suppression of star\nformation in these galaxies begins with a thermal mode of AGN feedback at z~6,\nand a kinetic feedback mode acts in each galaxy by z~4.7 to complete the\nquenching process, which occurs on a time-scale of ~0.35 Gyr. Surprisingly, we\nfind that the majority of these galaxies are not the main progenitors of their\nz=0 descendants; instead, four of the five galaxies fall into more massive\ngalaxies in subsequent mergers at a range of redshifts 2.5 < z < 0.2. By z=0,\nthese descendants are the centres of galaxy clusters with average stellar\nmasses of 8 x 10^{11} M_sun. We make predictions for the first quenched\ngalaxies to be located by the James Webb Space Telescope (JWST).", "positive": "deepCool: Fast and Accurate Estimation of Cooling Rates in Irradiated\n Gas with Artificial Neural Networks: Accurate models of radiative cooling are a fundamental ingredient of modern\ncosmological simulations. Without cooling, accreted baryons will not\nefficiently dissipate their energy and collapse to the centres of haloes to\nform stars. It is well established that local variations in the amplitude and\nshape of the spectral energy distribution of the radiation field can\ndrastically alter the cooling rate. Here we introduce deepCool, deepHeat, and\ndeepMetal: methods for accurately modelling the total cooling rates, total\nheating rates, and metal-line only cooling rates of irradiated gas using\nartificial neural networks. We train our algorithm on a high-resolution\ncosmological radiation hydrodynamics simulation and demonstrate that we can\npredict the cooling rate, as measured with the photoionisation code CLOUDY,\nunder the influence of a local radiation field, to an accuracy of ~5%. Our\nmethod is computationally and memory efficient, making it suitable for\ndeployment in state-of-the-art radiation hydrodynamics simulations. We show\nthat the circumgalactic medium and diffuse gas surrounding the central regions\nof a galaxy are most affected by the interplay of radiation and gas, and that\nstandard cooling functions that ignore the local radiation field can\nincorrectly predict the cooling rate by more than an order of magnitude,\nindicating that the baryon cycle in galaxies is affected by the influence of a\nlocal radiation field on the cooling rate." }, { "anchor": "Discovery of a disrupting open cluster far into the Milky Way halo: a\n recent star formation event in the leading arm of the Magellanic stream?: We report the discovery of a young (${\\rm age} \\sim 130~{\\rm Myr}$), low-mass\n($M \\sim 1200~{\\rm M}_\\odot$), metal-poor ($[{\\rm Fe}/{\\rm H}] \\sim -1.1$)\nstellar association at a heliocentric distance $D \\approx 29~{\\rm kpc}$,\nplacing it far into the Milky Way halo. At its present Galactocentric position\n$(R, z) \\sim (23, 15)~{\\rm kpc}$, the association is (on the sky) near the\nleading arm of the gas stream emanating from the Magellanic cloud system, but\nis located $\\approx 60^\\circ$ from the Large Magellanic Cloud (LMC) center on\nthe other side of the Milky Way disk. If we assume that the cluster is\nco-located with HI gas in the stream, we directly measure the distance to the\nleading arm of the Magellanic stream. The measured distance is inconsistent\nwith stream predictions from models of the LMC/SMC interaction and infall into\nthe Milky Way that do not account for ram pressure and gas interaction with\nMilky Way disk. The estimated age of the cluster is consistent with the time of\nlast passage of the leading arm gas through the Galactic midplane, and we\ntherefore speculate that this star-formation event was triggered by its the\nlast disk midplane passage. Most details of this idea remain a puzzle: the\nMagellanic stream has low column density, the Milky Way disk at this large\nradius has low gas density, and the relative velocity of the leading arm gas\nand Milky Way gas is large. However it formed, the discovery of a young stellar\ncluster in the Milky Way halo presents an interesting opportunity for study.\nThis cluster was discovered with Gaia astrometry and photometry alone, but\nfolow-up DECam photometry was crucial for measuring its properties.", "positive": "Kinematic decomposition of IllustrisTNG disk galaxies: morphology and\n relation with morphological structures: We recently developed an automated method, auto-GMM to decompose simulated\ngalaxies. It extracts kinematic structures in an accurate, efficient, and\nunsupervised way. We use auto-GMM to study the stellar kinematic structures of\ndisk galaxies from the TNG100 run of IllustrisTNG. We identify four to five\nstructures that are commonly present among the diverse galaxy population.\nStructures having strong to moderate rotation are defined as cold and warm\ndisks, respectively. Spheroidal structures dominated by random motions are\nclassified as bulges or stellar halos, depending on how tightly bound they are.\nDisky bulges are structures that have moderate rotation but compact morphology.\nAcross all disky galaxies and accounting for the stellar mass within 3\nhalf-mass radii, the kinematic spheroidal structures, obtained by summing up\nstars of bulges and halos, contribute ~45% of the total stellar mass, while the\ndisky structures constitute 55%. This study also provides important insights\nabout the relationship between kinematically and morphologically derived\ngalactic structures. Comparing the morphology of kinematic structures with that\nof traditional bulge+disk decomposition, we conclude: (1) the morphologically\ndecomposed bulges are composite structures comprised of a slowly rotating\nbulge, an inner halo, and a disky bulge; (2) kinematically disky bulges, akin\nto what are commonly called pseudo bulges in observations, are compact\ndisk-like components that have rotation similar to warm disks; (3) halos\ncontribute almost 30% of the surface density of the outer part of morphological\ndisks when viewed face-on; and (4) both cold and warm disks are often truncated\nin central regions." }, { "anchor": "Carriers of 4964 and 6196 diffuse interstellar bands and environments\n dominated by either CH or CH$^{+}$ molecules: The analysis of radial velocities of interstellar spectral features: CH,\nCH$^{+}$ as well as 4964 and 6196 diffuse interstellar bands, seen in spectra\nof HD 151932 and 152233, suggests that carrier of the former is spatially\ncorrelated with CH while that of the latter -- with CH$^{+}$. A further\nanalysis, done in this paper and based on the sample of 106 reddened OB stars,\npartly confirms this suggestion, showing that the CH column density correlates\nindeed much better with the equivalent width of the 4964 DIB than with that of\nthe 6196 DIB. However, the strengths of the 6196 DIB correlate only marginally\nbetter with CH$^+$ than with CH.", "positive": "Hoyle-Lyttleton accretion on to black hole accretion disks with\n super-Eddington luminosity for dusty gas: We investigate the Hoyle-Lyttleton accretion of dusty-gas for the case where\nthe central source is the black hole accretion disk. By solving the equation of\nmotion taking into account the radiation force which is attenuated by the dust\nabsorption, we reveal the steady structure of the flow around the central\nobject. We find that the mass accretion rate tends to increase with an increase\nof the optical thickness of the flow and the gas can accrete even if the disk\nluminosity exceeds the Eddington luminosity for the dusty-gas, since the\nradiation force is weakened by the attenuation via the dust absorption. When\nthe gas flows in from the direction of the rotation axis for the disk with\n${\\Gamma}^{'}=3.0$, the accretion rate is about 93% of the Hoyle-Lyttleton\naccretion rate if ${\\tau}_{\\rm{HL}}=3.3$ and zero for ${\\tau}_{\\rm{HL}}=1.0$,\nwhere ${\\Gamma}^{'}$ is the Eddington ratio for the dusty-gas and\n${\\tau}_{\\rm{HL}}$ is the typical optical thickness of the Hoyle-Lyttleton\nradius. Since the radiation flux in the direction of disk plane is small, the\nradiation force tends not to prevent gas accretion from the direction near the\ndisk plane. For ${\\tau}_{\\rm{HL}}=3.3$ and ${\\Gamma}^{'}=3.4$, although the\naccretion is impossible in the case of ${\\Theta}=0$, the accretion rate is 28%\nof the Hoyle-Lyttleton one in the case of ${\\Theta}=90$, where ${\\Theta}$ is\nthe angle between the direction the gas is coming from and the rotation axis of\nthe disk. We also obtain relatively high accretion luminosity that is realized\nwhen the accretion rate of the disk onto the BH is consistent with that via the\nHoyle-Lyttleton mechanism taking into account the effect of radiation. This\nimplies the intermediate-mass black holes moving in the dense dusty-gas are\nidentified as luminous objects in the infrared band." }, { "anchor": "A statistical method to determine open cluster metallicities: The study of open cluster metallicities helps to understand the local stellar\nformation and evolution throughout the Milky Way. Its metallicity gradient is\nan important tracer for the Galactic formation in a global sense. Because open\nclusters can be treated in a statistical way, the error of the cluster mean is\nminimized. Our final goal is a semi-automatic statistical robust method to\nestimate the metallicity of a statistically significant number of open clusters\nbased on Johnson BV data of their members, an algorithm that can easily be\nextended to other photometric systems for a systematic investigation. This\nmethod incorporates evolutionary grids for different metallicities and a\ncalibration of the effective temperature and luminosity. With cluster\nparameters (age, reddening and distance) it is possible to estimate the\nmetallicity from a statistical point of view. The iterative process includes an\nintrinsic consistency check of the starting input parameters and allows us to\nmodify them. We extensively tested the method with published data for the\nHyades and selected sixteen open clusters within 1000pc around the Sun with\navailable and reliable Johnson BV measurements. In addition, Berkeley 29, with\na distance of about 15kpc was chosen. For several targets we are able to\ncompare our result with published ones which yielded a very good coincidence\n(including Berkeley 29).", "positive": "A Critical Assessment of Solutions to the Galaxy Diversity Problem: Galactic rotation curves exhibit a diverse range of inner slopes.\nObservational data indicates that explaining this diversity may require a\nmechanism that correlates a galaxy's surface brightness with the central-most\nregion of its dark matter halo. In this work, we compare several concrete\nmodels that capture the relevant physics required to explain the galaxy\ndiversity problem. We focus specifically on a Self-Interacting Dark Matter\n(SIDM) model with an isothermal core and two Cold Dark Matter (CDM) models\nwith/without baryonic feedback. In contrast to the CDM case, the SIDM model can\nlead to the formation of an isothermal core in the halo, and is also mostly\ninsensitive to baryonic feedback processes, which act on longer time-scales.\nUsing rotation curves from 90 galaxies in the Spitzer Photometry and Accurate\nRotation Curves (SPARC) catalog, we perform a comprehensive model comparison\nthat addresses issues of statistical methodology from prior works. The best-fit\nhalo models that we recover are consistent with standard CDM concentration-mass\nand abundance matching relations. We find that both the SIDM and\nfeedback-affected CDM models are better than a CDM model with no feedback in\nexplaining the rotation curves of low and high surface brightness galaxies in\nthe sample. However, when compared to each other, there is no strong\nstatistical preference for either the SIDM or the feedback-affected CDM halo\nmodel as the source of galaxy diversity in the SPARC catalog." }, { "anchor": "OVI Emission From the Supernovae-regulated Interstellar Medium:\n Simulation Vs Observation: The OVI $\\lambda\\lambda$1032, 1038\\AA\\ doublet emission traces collisionally\nionized gas with $T\\approx 10^{5.5}$ K, where the cooling curve peaks for\nmetal-enriched plasma. This warm-hot phase is usually not well-resolved in\nnumerical simulations of the multiphase interstellar medium (ISM), but can be\nresponsible for a significant fraction of the emitted energy. Comparing\nsimulated OVI emission to observations is therefore a valuable test of whether\nsimulations predict reasonable cooling rates from this phase. We calculate OVI\n$\\lambda$1032\\AA\\ emission, assuming collisional ionization equilibrium, for\nour small-box simulations of the stratified ISM regulated by supernovae. We\nfind that the agreement is very good for our solar neighborhood model, both in\nterms of emission flux and mean OVI density seen in absorption. We explore runs\nwith higher surface densities and find that, in our simulations, the OVI\nemission from the disk scales roughly linearly with the star formation rate.\nObservations of OVI emission are rare for external galaxies, but our results do\nnot show obvious inconsistency with the existing data. Assuming the solar\nmetallicity, OVI emission from the galaxy disk in our simulations accounts for\nroughly 0.5\\% of supernovae heating.", "positive": "Resolved Star Formation Efficiency in the Antennae Galaxies: We use Atacama Large Millimeter Array CO(3-2) observations in conjunction\nwith optical observations from the Hubble Space Telescope to determine the\nratio of stellar to gas mass for regions in the Antennae Galaxies. We adopt the\nterm \"instantaneous mass ratio\" IMR(t) = M$_{stars}$/(M$_{gas}$ +M$_{stars}$),\nthat is equivalent to the star formation efficiency for an idealized system at\nt = 0. We use two complementary approaches to determining the IMR(t) based on\n1) the enclosed stellar and molecular mass within circular apertures centered\non optically-identified clusters, and 2) a tessellation algorithm that defines\nregions based on CO emission. We find that only a small number of clusters\nappear to have IMR(0) = SFE > 0.2, which suggests that only a small fraction of\nthese clusters will remain bound. The results suggest that by ages of\n$10^{6.7}$ years, some clusters will have lost all of their associated\nmolecular gas, and by $10^{7.5}$ years this is true for the majority of\nclusters. There appears to be slight dependence of the IMR(t) on the CO surface\nbrightness, which could support the idea that dense molecular environments are\nmore likely to form bound clusters. However, the IMR(t) appears to have a\nstrong dependence on extinction, which likely traces the evolutionary state of\nclusters." }, { "anchor": "Physical conditions and redshift evolution of optically thin C III\n absorbers: Low-z sample: We present a detailed analysis of 99 optically thin C III absorption systems\nat redshift, $0.2 \\le z \\le 0.9$ associated with neutral hydrogen column\ndensities in the range, $15 \\le {\\rm log}$ $N_{\\rm H\\,I}$ ($cm^{-2}$) $\\le\n16.2$. Using photoionization models, we infer the number density ($n_{\\rm H}$),\nC-abundance ($[C/H]$) and line-of-sight thickness ($L$) of these systems in the\nranges, $-3.4 \\le$ log $n_{\\rm H}$ (in $cm^{-3}$) $\\le -1.6$, $-1.6 \\le [C/H]\n\\le 0.4$, and 1.3 pc $\\le L \\le$ 10 kpc, respectively with most of the systems\nhaving sub-kpc scale thickness. We combine the low$-z$ and previously reported\nhigh$-z$ ($2.1\\le z\\le 3.3$) optically thin C III systems to study the redshift\nevolution and various correlation between the derived physical parameters. We\nsee a significant redshift evolution in $n_{\\rm H}$, $[C/H]$ and $L$. We\ncompare the redshift evolution of metallicity in C III systems with those of\nvarious types of absorption systems. We find that the slope of $[C/H]$ vs. $z$\nfor C III absorbers is stepper compared to the redshift evolution of cosmic\nmetallicity of the damped \\lya\\ sample (DLAs) but consistent with that of\nsub$-$DLAs. We find the existence of strong anti-correlation between $L$ vs.\n$[C/H]$ for the combined sample with a significance level of 8.39$\\sigma$. We\nsee evidence of two distinct $[C/H]$ branch C III populations (low$-[C/H]$\nbranch, $[C/H]$ $\\le -1.2$ and high$-[C/H]$ branch, $[C/H]$ $> -1.2$) in the\ncombined C III sample when divided appropriately in the $L$ vs. $N_{\\rm\nC\\,III}$ plane. Further studies of C III absorbers in the redshift range, $1.0\n\\le z \\le 2.0$ is important to map the redshift evolution of these absorbers\nand gain insights into the time evolution physical conditions of the\ncircumgalactic medium.", "positive": "High-resolution VLA observations of FR0 radio galaxies: properties and\n nature of compact radio sources: We present the results of Karl G. Jansky Very Large Array (VLA) observations\nto study the properties of FR0 radio galaxies, the compact radio sources\nassociated with early-type galaxies which represent the bulk of the local\nradio-loud AGN population. We obtained A-array observations at 1.5, 4.5, and\n7.5 GHz for 18 FR0s from the FR0CAT sample: these are sources at $z<0.05$,\nunresolved in the FIRST images and spectroscopically classified as low\nexcitation galaxies (LEG). Although we reach an angular resolution of $\\sim$0.3\narcsec, the majority of the 18 FR0s is still unresolved. Only four objects show\nextended emission. Six have steep radio spectra, 11 are flat cores, while one\nshows an inverted spectrum. We find that 1) the ratio between core and total\nemission in FR0s is $\\sim$30 times higher than in FRI and 2) FR0s share the\nsame properties with FRIs from the nuclear and host point of view. FR0s differ\nfrom FRIs only for the paucity of extended radio emission. Different scenarios\nwere investigated: 1) the possibility that all FR0s are young sources\neventually evolving into extended sources is ruled out by the distribution of\nradio sizes; 2) similarly, a time-dependent scenario, where a variation of\naccretion or jet launching prevents the formation of large-scales radio\nstructures, appears to be rather implausible due to the large abundance of\nsub-kpc objects 3) a scenario in which FR0s are produced by mildly relativistic\njets is consistent with the data but requires observations of a larger sample\nto be properly tested." }, { "anchor": "ELVES II: GCs and Nuclear Star Clusters of Dwarf Galaxies; The\n Importance of Environment: We present the properties of the globular clusters (GCs) and nuclear star\nclusters (NSCs) of low-mass ($10^{5.5} 4$ with an IR-derived ${\\rm SFR\n\\sim 4300 \\,} M_\\odot \\, {\\rm yr}^{-1}$. SGP38326 also contains a molecular gas\nreservoir among the most massive ever found in the early Universe, and it is\nthe likely progenitor of a massive, red-and-dead elliptical galaxy at $z \\sim\n3$. Probing scales of $\\sim 0.1\"$ or $\\sim 800 \\, {\\rm pc}$ we find that the\nsmooth distribution of the continuum emission from cool dust grains contrasts\nwith the more irregular morphology of the gas, as traced by the [CII] fine\nstructure emission. The gas is also extended over larger physical scales than\nthe dust. The velocity information provided by the resolved [CII] emission\nreveals that the dynamics of the two components of SGP38326 are compatible with\ndisk-like, ordered rotation, but also reveals an ISM which is turbulent and\nunstable. Our observations support a scenario where at least a subset of the\nmost distant extreme starbursts are highly dissipative mergers of gas-rich\ngalaxies.", "positive": "Exploring the environment, magnetic fields, and feedback effects of\n massive high-redshift galaxies with [CII]: Massive galaxies are expected to grow through different transformative\nevolutionary phases where high-redshift starburst galaxies and quasars are\nexamples of such phases. The physical mechanisms driving these phases include\ncompanion galaxy interactions, active galactic nuclei feedback, and magnetic\nfields. Our aim is to characterize the physical properties and the environment\nof the submillimeter galaxy AzTEC-3 at z = 5.3 and the lensed quasar BRI\n0952-0115 at z = 4.4, to set a limit on the polarization properties, as well as\nplacing both in the broader context of galaxy evolution. We used full\npolarization, sub-arcsecond-resolution, ALMA band-7 observations of both BRI\n0952-0115 and AzTEC-3 and detect [CII] line emission towards both galaxies,\nalong with companions in each field. We present an updated gravitational\nlensing model for BRI 0952-0115. We present infrared luminosities,\nstar-formation rates, and [CII] line to infrared luminosity ratios for each\nsource. The [CII] emission line profile for both BRI 0952-0115 and AzTEC-3\nexhibit a broad, complex morphology, indicating the possible presence of\noutflows. We present evidence of a 'gas bridge' between AzTEC-3 and a companion\nsource. Using a simple dynamical mass estimate for the sources, we suggest that\nboth systems are undergoing minor or major mergers. No polarization is detected\nfor the [CII], placing an upper limit below that of theoretical predictions.\nOur results show that high-velocity wings are detected, indicating possible\nsigns of massive outflows; however, the presence of companion galaxies can\naffect the final interpretation. Furthermore, the results provide additional\nevidence in support of the hypothesis that massive galaxies form in overdense\nregions, growing through interactions. Finally, strong, ordered magnetic fields\nare unlikely to exist at the kiloparsec scale in the two studied sources." }, { "anchor": "Sheets, filaments and clumps - high resolution simulations of how the\n thermal instability can form molecular clouds: This paper describes 3D simulations of the formation of collapsing cold\nclumps via thermal instability inside a larger cloud complex. The initial\ncondition was a diffuse atomic, stationary, thermally unstable, 200pc diameter\nspherical cloud in pressure equilibrium with low density surroundings. This was\nseeded with 10% density perturbations at the finest initial grid level (0.29pc)\naround n_H = 1.1cm^{-3} and evolved with self-gravity included. No magnetic\nfield was imposed. Resimulations at a higher resolution of a region extracted\nfrom this simulation (down to 0.039pc), show that the thermal instability forms\nsheets, then filaments and finally clumps. The width of the filaments increases\nover time, in one particular case from 0.26 to 0.56pc. Thereafter clumps with\nsizes of around 5pc grow at the intersections of filaments. 21 distinct clumps,\nwith properties similar to those observed in molecular clouds, are found by\nusing the FellWalker algorithm to find minima in the gravitational potential.\nNot all of these are gravitationally bound, but the convergent nature of the\nflow and increasing central density suggest they are likely to form stars.\nFurther simulation of the most massive clump shows the gravitational collapse\nto a density >10^6 cm^{-3}. These results provide realistic initial conditions\nthat can be used to study feedback in individual clumps, interacting clumps and\nthe entire molecular cloud complex.", "positive": "Galactic kinematics of planetary nebulae with [WC] central star: High resolution spectra are used to analyze the galactic kinematics and\ndistribution of a sample of planetary nebulae with [WR] and 'wel' central star\n([WR]PN and WLPN). The circular and peculiar velocities (Vpec) of the objects\nwere derived. The results are: a) [WR]PNe are distributed mainly in the\ngalactic disk and they are more concentrated in a thinner disk than WLPNe and\nnormal PNe, which corresponds to a younger population; b) the sample was\nseparated in Peimbert's types, and it is found that Type I PNe have Vpec <50 km\ns-1, indicating young objects. Most of the [WR]PNe are of Type II showing Vpec\n<60 km s-1, although a small percentage is of Type III, with larger Vpec\nshowing that the Wolf-Rayet phenomenon in central stars can occur at any\nstellar mass and in old objects. None of our WLPNe is Type I. Thus, [WR]PNe and\nWLPNe are unrelated objects." }, { "anchor": "MOCCA-SURVEY Database I: Is NGC 6535 a Dark Star Cluster Harboring an\n IMBH?: We describe the dynamical evolution of a unique type of dark star cluster\nmodel in which the majority of the cluster mass at Hubble time is dominated by\nan intermediate-mass black hole (IMBH). We analyzed results from about 2000\nstar cluster models (Survey Database I) simulated using the Monte-Carlo code\nMOCCA and identified these dark star cluster models. Taking one of these\nmodels, we apply the method of simulating realistic \"mock observations\" by\nutilizing the COCOA and SISCO codes to obtain the photometric and kinematic\nobservational properties of the dark star cluster model at 12 Gyr. We find that\nthe perplexing Galactic globular cluster NGC 6535 closely matches the\nobservational photometric and kinematic properties of the dark star cluster\nmodel presented in this paper. Based on our analysis and currently observed\nproperties of NGC 6535, we suggest that this globular cluster could potentially\nharbour an IMBH. If it exists, the presence of this IMBH can be detected\nrobustly with proposed kinematic observations of NGC 6535.", "positive": "The Lyman alpha reference sample. VII. Spatially resolved H$\u03b1$\n kinematics: We present integral field spectroscopic observations with the Potsdam Multi\nAperture Spectrophotometer of all 14 galaxies in the $z\\sim 0.1$ Lyman Alpha\nReference Sample (LARS). We produce 2D line of sight velocity maps and velocity\ndispersion maps from the Balmer $\\alpha$ (H$\\alpha$) emission in our data\ncubes. These maps trace the spectral and spatial properties of the LARS\ngalaxies' intrinsic Ly$\\alpha$ radiation field. We show our kinematic maps\nspatially registered onto the Hubble Space Telescope H$\\alpha$ and Lyman\n$\\alpha$ (Ly$\\alpha$) images. Only for individual galaxies a causal connection\nbetween spatially resolved H$\\alpha$ kinematics and Ly$\\alpha$ photometry can\nbe conjectured. However, no general trend can be established for the whole\nsample. Furthermore, we compute non-parametric global kinematical statistics --\nintrinsic velocity dispersion $\\sigma_0$, shearing velocity $v_\\mathrm{shear}$,\nand the $v_\\mathrm{shear}/\\sigma_0$ ratio -- from our kinematic maps. In\ngeneral LARS galaxies are characterised by high intrinsic velocity dispersions\n(54\\,km\\,s$^{-1}$ median) and low shearing velocities (65\\,km\\,s$^{-1}$\nmedian). $v_\\mathrm{shear}/\\sigma_0$ values range from 0.5 to 3.2 with an\naverage of 1.5. Noteworthy, five galaxies of the sample are dispersion\ndominated systems with $v_\\mathrm{shear}/\\sigma_0 <1$ and are thus\nkinematically similar to turbulent star forming galaxies seen at high redshift.\nWhen linking our kinematical statistics to the global LARS Ly$\\alpha$\nproperties, we find that dispersion dominated systems show higher Ly$\\alpha$\nequivalent widths and higher Ly$\\alpha$ escape fractions than systems with\n$v_\\mathrm{shear}/\\sigma_0 > 1$. Our result indicates that turbulence in\nactively star-forming systems is causally connected to interstellar medium\nconditions that favour an escape of Ly$\\alpha$ radiation." }, { "anchor": "The UV Continuum Slopes of Early Star-Forming Galaxies in JADES: The power-law slope of the rest-UV continuum\n($f_{\\lambda}\\propto\\lambda^{\\beta}$) is a key metric of early star forming\ngalaxies, providing one of our only windows into the stellar populations and\nphysical conditions of $z>10$ galaxies. Expanding upon previous studies with\nlimited sample sizes, we leverage deep imaging from JADES to investigate the UV\nslopes of 179 $z>9$ galaxies with apparent magnitudes of $m_{\\rm F200W}=26-31$,\nwhich display a median UV slope of $\\beta=-2.4$. We compare to a statistical\nsample of $z=5-9$ galaxies, finding a shift toward bluer rest-UV colors at all\n$\\rm~M_{UV}$. The most UV-luminous $z>9$ galaxies are significantly bluer than\ntheir lower-redshift counterparts, representing a dearth of moderately-red\ngalaxies in the first $500~$Myr. At yet earlier times, the $z>11$ galaxy\npopulation exhibits very blue UV slopes, implying very low attenuation from\ndust. We identify a robust sample of 44 galaxies with $\\beta<-2.8$, which have\nSEDs requiring models of density-bounded HII regions and median ionizing photon\nescape fractions of $0.51$ to reproduce. Their rest-optical colors imply that\nthis sample has weaker emission lines (median $m_{\\rm F356W}-m_{\\rm\nF444W}=0.19$ mag) than typical galaxies (median $m_{\\rm F356W}-m_{\\rm\nF444W}=0.39$ mag), consistent with the inferred escape fractions. This sample\nhas relatively low stellar masses (median $\\log(M/M_{\\odot})=7.5$), and\nspecific star-formation rates (median$=79\\rm/Gyr$) nearly twice that of our\nfull sample (median$=44\\rm/Gyr$), suggesting they are more common among systems\nexperiencing a recent upturn in star formation. We demonstrate that the shutoff\nof star formation provides an alternative solution for modelling of extremely\nblue UV colors, making distinct predictions for the rest-optical emission of\nthese galaxies. Future spectroscopy will be required to distinguish between\nthese physical pictures.", "positive": "Formation of massive disk galaxies in the IllustrisTNG simulation: We investigate the formation history of massive disk galaxies in\nhydro-dynamical simulation--the IllustrisTNG, to study why massive disk\ngalaxies survive through cosmic time. 83 galaxies in the simulation are\nselected with M$_{*,z=0}$ $>8\\times10^{10}$ M$_\\odot$ and kinematic\nbulge-to-total ratio less than $0.3$. We find that 8.4 percent of these massive\ndisk galaxies have quiet merger histories and preserve disk morphology since\nformed. 54.2 percent have a significant increase in bulge components in\nhistory, then become disks again till present time. The rest 37.3 percent\nexperience prominent mergers but survive to remain disky. While mergers and\neven major mergers do not always turn disk galaxies into ellipticals, we study\nthe relations between various properties of mergers and the morphology of\nmerger remnants. We find a strong dependence of remnant morphology on the orbit\ntype of major mergers. Specifically, major mergers with a spiral-in falling\norbit mostly lead to disk-dominant remnants, and major mergers of head-on\ngalaxy-galaxy collision mostly form ellipticals. This dependence of remnant\nmorphology on orbit type is much stronger than the dependence on cold gas\nfraction or orbital configuration of merger system as previously studied." }, { "anchor": "The ALMA Spectroscopic Survey in the HUDF: Multi-band constraints on\n line luminosity functions and the cosmic density of molecular gas: We present a CO and atomic fine-structure line luminosity function analysis\nusing the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS).\nASPECS consists of two spatially-overlapping mosaics that cover the entire ALMA\n3mm and 1.2mm bands. We combine the results of a line candidate search of the\n1.2mm data cube with those previously obtained from the 3mm cube. Our analysis\nshows that $\\sim$80% of the line flux observed at 3mm arises from CO(2-1) or\nCO(3-2) emitters at $z$=1-3 (`cosmic noon'). At 1.2mm, more than half of the\nline flux arises from intermediate-J CO transitions ($J_{\\rm up}$=3-6);\n$\\sim12$% from neutral carbon lines; and $< 1$% from singly-ionized carbon,\n[CII]. This implies that future [CII] intensity mapping surveys in the epoch of\nreionization will need to account for a highly significant CO foreground. The\nCO luminosity functions probed at 1.2mm show a decrease in the number density\nat a given line luminosity (in units of $L'$) at increasing $J_{\\rm up}$ and\nredshift. Comparisons between the CO luminosity functions for different CO\ntransitions at a fixed redshift reveal sub-thermal conditions on average in\ngalaxies up to $z\\sim 4$. In addition, the comparison of the CO luminosity\nfunctions for the same transition at different redshifts reveals that the\nevolution is not driven by excitation. The cosmic density of molecular gas in\ngalaxies, $\\rho_{\\rm H2}$, shows a redshift evolution with an increase from\nhigh redshift up to $z\\sim1.5$ followed by a factor $\\sim 6$ drop down to the\npresent day. This is in qualitative agreement with the evolution of the cosmic\nstar-formation rate density, suggesting that the molecular gas depletion time\nis approximately constant with redshift, after averaging over the star-forming\ngalaxy population.", "positive": "The Infrared Jet in 3C31: We report the detection of infrared emission from the jet of the nearby FR I\nradio galaxy 3C 31. The jet was detected with the IRAC instrument on Spitzer at\n4.5 micron, 5.8 micron, and 8.0 micron out to 30\" (13 kpc) from the nucleus. We\nmeasure radio, infrared, optical, and X-ray fluxes in three regions along the\njet determined by the infrared and X-ray morphology. Radio through X-ray\nspectra in these regions demonstrate that the emission can be interpreted as\nsynchrotron emission from a broken power-law distribution of electron energies.\nWe find significant differences in the high energy spectra with increasing\ndistance from the nucleus. Specifically, the high energy slope increases from\n0.86 to 1.72 from 1 kpc to 12 kpc along the jet, and the spectral break\nlikewise increases in frequency along the jet from 10-100's of GHz to ~20 THz.\nThus the ratio of IR to X-ray flux in the jet increases by at least an order of\nmagnitude with increasing distance from the nucleus. We argue that these\nchanges cannot simply be the result of spectral aging and that there is ongoing\nparticle acceleration through this region of the jet. The effects of mass\nloading, turbulence, and jet deceleration, however these processes modify the\njet flow in detail, must be causing a change in the electron energy\ndistribution and the efficiency of particle acceleration." }, { "anchor": "Physics and Chemistry of Radiation Driven Cloud Evolution. [C II]\n Kinematics of IC 59 and IC 63: We used high-resolution [C II] 158 $\\mu$m mapping of two nebulae IC 59 and IC\n63 from SOFIA/upGREAT in conjunction with ancillary data on the gas, dust, and\npolarization to probe the kinematics, structure, and magnetic properties of\ntheir photo-dissociation regions (PDRs). The nebulae are part of the Sh 2-185 H\nII region illuminated by the B0 IVe star $\\gamma$ Cas. The velocity structure\nof each PDR changes with distance from $\\gamma$ Cas, consistent with driving by\nthe radiation. Based on previous FUV flux measurements of, and the known\ndistance to $\\gamma$ Cas along with the predictions of 3D distances to the\nclouds, we estimated the FUV radiation field strength (G0) at the clouds.\nAssuming negligible extinction between the star and clouds, we find their 3D\ndistances from $\\gamma$ Cas. For IC 63, our results are consistent with earlier\nestimates of distance from Andersson et al. (2013), locating the cloud at 2 pc\nfrom $\\gamma$ Cas, at an angle of 58 to the plane of the sky, behind the star.\nFor IC 59, we derive a distance of 4.5 pc at an angle of 70 in front of the\nstar. We do not detect any significant correlation between the orientation of\nthe magnetic field (Soam et al. 2017) and the velocity gradients of [C II] gas,\nindicating a moderate magnetic field strength. The kinetic energy in IC 63 is\nestimated to be order of ten higher than the magnetic energies. This suggests\nthat kinetic pressure in this nebula is dominant.", "positive": "OGLE Collection of Star Clusters. New Objects in the Magellanic Bridge\n and the Outskirts of the Small Magellanic Cloud: The Magellanic System (MS) encompasses the nearest neighbors of the Milky\nWay, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic\nBridge (MBR). This system contains a diverse sample of star clusters. Their\nparameters, such as the spatial distribution, chemical composition and age\ndistribution yield important information about the formation scenario of the\nwhole Magellanic System. Using deep photometric maps compiled in the fourth\nphase of the Optical Gravitational Lensing Experiment (OGLE-IV) we present the\nmost complete catalog of star clusters in the Magellanic System ever\nconstructed from homogeneous, long time-scale photometric data. In this second\npaper of the series, we show the collection of star clusters found in the area\nof about 360 square degrees in the MBR and in the outer regions of the SMC. Our\nsample contains 198 visually identified star cluster candidates, 75 of which\nwere not listed in any of the previously published catalogs. The new\ndiscoveries are mainly young small open clusters or clusters similar to\nassociations." }, { "anchor": "Calibrating Milky Way dust extinction using cosmological sources: We constrain the light extinction properties of Milky Way dust. We\ninvestigated the correlations between dust column density as inferred from\ninfrared data and the observed colours of celestial objects at cosmological\ndistances with low levels of colour dispersion. Results derived using colours\nof quasars, brightest central galaxies, and luminous red galaxies are broadly\nconsistent, indicating a proportionality constant between the reddening\nE(B-V)=A_B-A_V and the dust column density D^T (given in units of MJy/sr) of\np=E(B-V)/D^T=0.02 and a reddening parameter R_V=A_V/E(B-V)=3 with fractional\nuncertainties of approximately 10%. The data do not provide any evidence for\nspatial variations in the dust properties, except for a possible hint of\nscatter in the dust extinction properties at the longest optical wavelengths.", "positive": "A MUSE study of the inner bulge globular cluster Terzan 9: a fossil\n record in the Galaxy: Context. Moderately metal-poor inner bulge globular clusters are relics of a\ngeneration of long-lived stars that formed in the early Galaxy. Terzan 9,\nprojected at 4d 12 from the Galactic center, is among the most central globular\nclusters in the Milky Way, showing an orbit which remains confined to the inner\n1 kpc. Aims. Our aim is the derivation of the cluster's metallicity, together\nwith an accurate measurement of the mean radial velocity. In the literature,\nmetallicities in the range between have been estimated for Terzan 9 based on\ncolor-magnitude diagrams and CaII triplet (CaT) lines. Aims. Our aim is the\nderivation of the cluster's metallicity, together with an accurate measurement\nof the mean radial velocity. In the literature, metallicities in the range\nbetween -2.0 and -1.0 have been estimated for Terzan 9 based on color-magnitude\ndiagrams and CaII triplet (CaT) lines.\n Methods. Given its compactness, Terzan 9 was observed using the Multi Unit\nSpectroscopic Explorer (MUSE) at the Very Large Telescope. The extraction of\nspectra from several hundreds of individual stars allowed us to derive their\nradial velocities, metallicities, and [Mg/Fe]. The spectra obtained with MUSE\nwere analysed through full spectrum fitting using the ETOILE code.\n Results. We obtained a mean metallicity of [Fe/H] -1.10 0.15, a heliocentric\nradial velocity of vhr = 58.1 1.1 km/s , and a magnesium-to-iron [Mg/Fe] = 0.27\n0.03. The metallicity-derived character of Terzan 9 sets it among the family of\nthe moderately metal-poor Blue Horizontal Branch clusters HP 1, NGC 6558, and\nNGC 6522." }, { "anchor": "Galaxy Zoo: the effect of bar-driven fueling on the presence of an\n active galactic nucleus in disc galaxies: We study the influence of the presence of a strong bar in disc galaxies which\nhost an active galactic nucleus (AGN). Using data from the Sloan Digital Sky\nSurvey and morphological classifications from the Galaxy Zoo 2 project, we\ncreate a volume-limited sample of 19,756 disc galaxies at $0.017$), and its variation in the rest-frame wavelength range\nbetween Lyman $\\alpha$ and 6000-4000\\AA, at $z=7-12$. We find no dramatic\nvariations in morphology with wavelength -- of the kind that would have\noverturned anything we have learned from the Hubble Space Telescope. No\nsignificant trends between morphology and wavelengths are detected using\nstandard quantitative morphology statistics. We detect signatures of\nmergers/interactions in 4/19 galaxies. Our results are consistent with a\nscenario in which Lyman Break galaxies -- observed when the universe is only\n400-800 Myrs old - are growing via a combination of rapid galaxy-scale star\nformation supplemented by accretion of star forming clumps and interactions.", "positive": "A search for distant, pulsating red giants in the southern halo: To investigate the asymptotic giant branch (AGB) population in the Galactic\nhalo, we search for pulsating AGB stars at a heliocentric distance over 50kpc.\nOur research is based on the Catalina Southern Survey (CSS) catalogue of\nvariables, comprising 1286 long-period variables (LPVs) with declination less\nthan -20deg. We first focus on the 77 stars in the cap abs(b)>30deg for which\nspectral M-type or C-type classification can be derived from Hamburg-ESO\nobjective prism spectra. Most of these are oxygen-rich (M-type) and very few\nare carbon rich. The periods are in the range 100-500 days, and CSS amplitudes\nare up to 3 mag. In this small sample, no halo AGB star is fainter than\nKs0=12.5. This may be due to the scarcity of AGBs in the outer halo, or\ninsufficient instrumental depth. Leaving aside spectral information, we then\nsearched for even fainter pulsators (Ks>12.5) in the entire CSS catalogue. Gaia\nastrometry makes it possible to identify some contaminants. Our final result is\nthe identification of ten candidate distant LPVs. If these ten stars obey the\nfundamental mode K-band period luminosity relation used for Miras and\nsmall-amplitude Miras, their distances are between 50 and 120kpc from the Sun.\nIn a diagram showing distance versus Gaia tangential velocity, these ten stars\nhave positions similar to those of other objects in the halo, such as globular\nclusters and dwarf galaxies. We also detect some underluminous AGBs that\ndeserve further study. A detailed catalogue of the 77 high-latitude M or C\nstars will be made available at the CDS." }, { "anchor": "A non-equilibrium ionization model of the Local Bubble (I): Aims. We present the first high-resolution non-equilibrium ionization\nsimulation of the joint evolution of the Local Bubble (LB) and Loop I\nsuperbubbles in the turbulent supernova-driven interstellar medium (ISM). The\ntime variation and spatial distribution of the Li-like ions Civ, Nv, and Ovi\ninside the LB are studied in detail.\n Methods. This work uses the parallel adaptive mesh refinement code EAF-PAMR\ncoupled to the newly developed atomic and molecular plasma emission module\nE(A+M)PEC, featuring the time-dependent calculation of the ionization structure\nof H through Fe, using the latest revision of solar abundances. The finest AMR\nresolution is 1 pc within a grid that covers a representative patch of the\nGalactic disk (with an area of 1 kpc^2 in the midplane) and halo (extending up\nto 10 kpc above and below the midplane).\n Results. The evolution age of the LB is derived by the match between the\nsimulated and observed absorption features of the Li-like ions Civ, Nv, and Ovi\n. The modeled LB current evolution time is bracketed between 0.5 and 0.8 Myr\nsince the last supernova reheated the cavity in order to have N(Ovi) < 8 \\times\n10^12 cm-2, log[N(Civ) /N(Ovi) ] < -0.9 and log[N(Nv) /N(Ovi) ] < -1 inside the\nsimulated LB cavity, as found in Copernicus, IUE, GHRS-IST and FUSE\nobservations.", "positive": "Albatross: A scalable simulation-based inference pipeline for analysing\n stellar streams in the Milky Way: Stellar streams are potentially a very sensitive observational probe of\ngalactic astrophysics, as well as the dark matter population in the Milky Way.\nOn the other hand, performing a detailed, high-fidelity statistical analysis of\nthese objects is challenging for a number of key reasons. Firstly, the\nmodelling of streams across their (potentially billions of years old) dynamical\nage is complex and computationally costly. Secondly, their detection and\nclassification in large surveys such as Gaia renders a robust statistical\ndescription regarding e.g., the stellar membership probabilities, challenging.\nAs a result, the majority of current analyses must resort to simplified models\nthat use only subsets or summaries of the high quality data. In this work, we\ndevelop a new analysis framework that takes advantage of advances in\nsimulation-based inference techniques to perform complete analysis on complex\nstream models. To facilitate this, we develop a new, modular dynamical\nmodelling code sstrax for stellar streams that is highly accelerated using jax.\nWe test our analysis pipeline on a mock observation that resembles the GD1\nstream, and demonstrate that we can perform robust inference on all relevant\nparts of the stream model simultaneously. Finally, we present some outlook as\nto how this approach can be developed further to perform more complete and\naccurate statistical analyses of current and future data." }, { "anchor": "Finding, characterizing and classifying variable sources in multi-epoch\n sky surveys: QSOs and RR Lyrae in PS1 3$\u03c0$ data: In area and depth, the Pan-STARRS1 (PS1) 3$\\pi$ survey is unique among\nmany-epoch, multi-band surveys and has enormous potential for all-sky\nidentification of variable sources. PS1 has observed the sky typically seven\ntimes in each of its five bands ($grizy$) over 3.5 years, but unlike SDSS not\nsimultaneously across the bands. Here we develop a new approach for quantifying\nstatistical properties of non-simultaneous, sparse, multi-color lightcurves\nthrough light-curve structure functions, effectively turning PS1 into a $\\sim\n35$-epoch survey. We use this approach to estimate variability amplitudes and\ntimescales $(\\omega_r, \\tau)$ for all point-sources brighter than\n$r_{\\mathrm{P1}}=21.5$ mag in the survey. With PS1 data on SDSS Stripe 82 as\n``ground truth\", we use a Random Forest Classifier to identify QSOs and RR\nLyrae based on their variability and their mean PS1 and WISE colors. We find\nthat, aside from the Galactic plane, QSO and RR Lyrae samples of purity\n$\\sim$75\\% and completeness $\\sim$92\\% can be selected. On this basis we have\nidentified a sample of $\\sim 1,000,000$ QSO candidates, as well as an\nunprecedentedly large and deep sample of $\\sim$150,000 RR Lyrae candidates with\ndistances from $\\sim$10 kpc to $\\sim$120 kpc. Within the Draco dwarf\nspheroidal, we demonstrate a distance precision of 6\\% for RR Lyrae candidates.\nWe provide a catalog of all likely variable point sources and likely QSOs in\nPS1, a total of $25.8\\times 10^6$ sources.", "positive": "Unveiling the Structure of Barred Galaxies at 3.6 $\u03bc{\\rm m}$ with the\n Spitzer Survey of Stellar Structure in Galaxies (S$^4$G): I. Disk Breaks: We have performed two-dimensional multicomponent decomposition of 144 local\nbarred spiral galaxies using 3.6 $\\mu {\\rm m}$ images from the Spitzer Survey\nof Stellar Structure in Galaxies. Our model fit includes up to four components\n(bulge, disk, bar, and a point source) and, most importantly, takes into\naccount disk breaks. We find that ignoring the disk break and using a single\ndisk scale length in the model fit for Type II (down-bending) disk galaxies can\nlead to differences of 40% in the disk scale length, 10% in bulge-to-total\nluminosity ratio (B/T), and 25% in bar-to-total luminosity ratios. We find that\nfor galaxies with B/T $\\geq$ 0.1, the break radius to bar radius, $r_{\\rm\nbr}/R_{\\rm bar}$, varies between 1 and 3, but as a function of B/T the ratio\nremains roughly constant. This suggests that in bulge-dominated galaxies the\ndisk break is likely related to the outer Lindblad Resonance (OLR) of the bar,\nand thus moves outwards as the bar grows. For galaxies with small bulges, B/T\n$<$ 0.1, $r_{\\rm br}/R_{\\rm bar}$ spans a wide range from 1 to 6. This suggests\nthat the mechanism that produces the break in these galaxies may be different\nfrom that in galaxies with more massive bulges. Consistent with previous\nstudies, we conclude that disk breaks in galaxies with small bulges may\noriginate from bar resonances that may be also coupled with the spiral arms, or\nbe related to star formation thresholds." }, { "anchor": "Galaxy sizes and the galaxy-halo connection -- I: the remarkable\n tightness of the size distributions: The mass and structural assembly of galaxies is a matter of intense debate.\nCurrent theoretical models predict the existence of a linear relationship\nbetween galaxy size ($R_e$) and the host dark matter halo virial radius\n($R_h$).\\\\ By making use of semi-empirical models compared to the size\ndistributions of central galaxies from the Sloan Digital Sky Survey, we provide\nrobust constraints on the normalization and scatter of the $R_e-R_h$ relation.\nWe explore the parameter space of models in which the $R_e-R_h$ relation is\nmediated by either the spin parameter or the concentration of the host halo, or\na simple constant the nature of which is in principle unknown. We find that the\ndata require extremely tight relations for both early-type and late-type\ngalaxies (ETGs,LTGs), especially for more massive galaxies. These constraints\nchallenge models based solely on angular momentum conservation, which predict\nsignificantly wider distributions of galaxy sizes and no trend with stellar\nmass, if taken at face value. We discuss physically-motivated alterations to\nthe original models that bring the predictions into better agreement with the\ndata. We argue that the measured tight size distributions of SDSS disk galaxies\ncan be reproduced by semi-empirical models in which the $R_e-R_h$ connection is\nmediated by the \\emph{stellar} specific angular momenta $j_{star}.$ We find\nthat current cosmological models of galaxy formation broadly agree with our\nconstraints for LTGs, and justify the strong link between $R_e$ and $j_{star}$\nthat we propose, however the tightness of the $R_e-R_h$ relation found in such\nab-initio theoretical models for ETGs is in tension with our semi-empirical\nfindings.", "positive": "Three regimes of black hole feedback: In theoretical models of galaxy evolution, black hole feedback is a necessary\ningredient in order to explain the observed exponential decline in number\ndensity of massive galaxies. Most contemporary black hole feedback models in\ncosmological simulations rely on a constant radiative efficiency (usually $\\eta\n\\sim 0.1$) at all black hole accretion rates. We present a synthesis model for\nthe spin-dependent radiative efficiencies of three physical accretion rate\nregimes, i.e. $\\eta = \\eta(j, \\dot{M}_\\mathrm{BH})$, for use in large-volume\ncosmological simulations. The three regimes include: an advection dominated\naccretion flow ($\\dot{M}_\\mathrm{BH} < 0.03\\,\\dot{M}_\\mathrm{Edd}$), a\nquasar-like mode ($0.03 < \\dot{M}_\\mathrm{BH} / \\dot{M}_\\mathrm{Edd} < 0.3$),\nand a slim disc mode ($\\dot{M}_\\mathrm{BH} > 0.3\\,\\dot{M}_\\mathrm{Edd}$).\nAdditionally, we include a large-scale powerful jet at low accretion rates. The\nblack hole feedback model we present is a kinetic model that prescribes mass\nloadings but could be used in thermal models directly using the radiative\nefficiency. We implemented our model into the \\texttt{Simba} galaxy evolution\nmodel to determine if it is possible to reproduce galaxy populations\nsuccessfully, and provide a first calibration for further study. Using a\n$2\\times1024^3$ particle cosmological simulation in a $(150\\,\\mathrm{cMpc})^3$\nvolume, we found that the model is successful in reproducing the galaxy stellar\nmass function, black hole mass-stellar mass relationship, and stellar mass-halo\nmass relationship. Our model shines when we extrapolate to the galaxy group and\ncluster scale as it impressively predicts the observed baryon fraction within\nmassive groups and low-mass clusters. Moving forward, this model opens new\navenues for exploration of the impact of black hole feedback on galactic\nenvironments." }, { "anchor": "SDSS IV MaNGA: Deep observations of extra-planar, diffuse ionized gas\n around late-type galaxies from stacked IFU spectra: We have conducted a study of extra-planar diffuse ionized gas using the first\nyear data from the MaNGA IFU survey. We have stacked spectra from 49 edge-on,\nlate-type galaxies as a function of distance from the midplane of the galaxy.\nWith this technique we can detect the bright emission lines Halpha, Hbeta,\n[OII]3726, 3729, [OIII]5007, [NII]6549, 6584, and [SII]6717, 6731 out to about\n4 kpc above the midplane. With 16 galaxies we can extend this analysis out to\nabout 9 kpc, i.e. a distance of ~2R_e, vertically from the midplane. In the\nhalo, the surface brightnesses of the [OII] and Halpha emission lines are\ncomparable, unlike in the disk where Halpha dominates. When we split the sample\nby specific star formation rate, concentration index, and stellar mass, each\nsubsample's emission line surface brightness profiles and ratios differ,\nindicating that extra-planar gas properties can vary. The emission line surface\nbrightnesses of the gas around high specific star formation rate galaxies are\nhigher at all distances, and the line ratios are closer to ratios\ncharacteristic of HII regions compared with low specific star formation rate\ngalaxies. The less concentrated and lower stellar mass samples exhibit line\nratios that are more like HII regions at larger distances than their more\nconcentrated and higher stellar mass counterparts. The largest difference\nbetween different subsamples occurs when the galaxies are split by stellar\nmass. We additionally infer that gas far from the midplane in more massive\ngalaxies has the highest temperatures and steepest radial temperature gradients\nbased on their [NII]/Halpha and [OII]/Halpha ratios between the disk and the\nhalo.", "positive": "Fragmentation and dynamics of dense gas structures in the proximity of\n massive young stellar object W42-MME: We present an analysis of the dense gas structures in the immediate\nsurroundings of the massive young stellar object (MYSO) W42-MME, using the\nhigh-resolution (0$''$.31$\\times$0$''$.25) ALMA dust continuum and molecular\nline data. We performed a dendrogram analysis of H$^{13}$CO$^{+}$ (4-3) line\ndata to study multi-scale structures and their spatio-kinematic properties, and\nanalyzed the fragmentation and dynamics of dense structures down to $\\sim$2000\nAU scale. Our results reveal 19 dense gas structures, out of which 12 are\nleaves and 7 are branches in dendrogram terminology. These structures exhibit\ntransonic-supersonic gas motions (1$<\\mathcal{M}<5$) with overvirial states\n($\\alpha_{\\rm vir}\\geq2$). The non-thermal velocity dispersion-size relation\n($\\sigma_{\\rm nt}-L$) of dendrogram structures shows a weak negative\ncorrelation, while the velocity dispersion across the sky\n($\\delta\\mathit{V_{\\rm lsr}}$) correlates positively with structure size ($L$).\nVelocity structure function ($S_{2}(l)^{1/2}$) analysis of H$^{13}$CO$^{+}$\ndata reveals strong power-law dependencies with lag ($l$) up to a scale length\nof $\\lesssim$ 6000 AU. The mass-size ($M-R$) relation of dendrogram structures\nshows a positive correlation with power-law index of 1.73$\\pm$0.23, and the\nleaf L17 hosting W42-MME meets the mass-size conditions for massive star\nformation. Blue asymmetry is observed in the H$^{12}$CO$^{+}$ (4-3) line\nprofiles of most of the leaves, indicating infall. Overall, our results\nobservationally support the hierarchical and chaotic collapse scenario in the\nproximity of the MYSO W42-MME." }, { "anchor": "The Widefield Arecibo Virgo Extragalactic Survey: Early Results on Known\n Dark Sources: The Widefield Arecibo Virgo Extragalactic Survey (WAVES) was an ongoing HI\nsurvey of the Virgo Cluster with the Arecibo Observatory's 305m William E.\nGordon Telescope at the time of its structural failure. The full 20 square\ndegrees of the southern field and 10 of the planned 35 square degrees of the\nnorthern field had been observed to full depth, adding to 25 square degrees\nobserved to the same depth in the cluster by the Arecibo Galaxy Environment\nSurvey. We here review what WAVES reveals about four optically dark HI\nstructures that were previously discovered in the survey area, including two\nthat are not seen despite being well above our detection limit.", "positive": "Red but not dead : Unveiling the Star-forming Far-infrared Spectral\n Energy Distribution of SpARCS Brightest Cluster Galaxies at 0 < z < 1.8: We present the results of a Spitzer/Herschel infrared photometric analysis of\nthe largest (716) and highest-redshift (z=1.8) sample of Brightest Cluster\nGalaxies (BCGs), those from the Spitzer Adaptation of the Red-Sequence Cluster\nSurvey (SpARCS). Given the tension that exists between model predictions and\nrecent observations of BCGs at z<2, we aim to uncover the dominant physical\nmechanism(s) guiding the stellar-mass buildup of this special class of\ngalaxies, the most massive in the Universe uniquely residing at the centres of\ngalaxy clusters. Through a comparison of their stacked, broadband, infrared\nspectral energy distributions (SEDs) to a variety of SED model templates in the\nliterature, we identify the major sources of their infrared energy output, in\nmultiple redshift bins between 0 < z < 1.8. We derive estimates of various BCG\nphysical parameters from the stacked {\\nu}L{\\nu} SEDs, from which we infer a\nstar-forming, as opposed to a 'red and dead' population of galaxies, producing\ntens to hundreds of solar masses per year down to z=0.5. This discovery\nchallenges the accepted belief that BCGs should only passively evolve through a\nseries of gas-poor, minor mergers since z~4 (De Lucia & Blaizot 2007), but\nagrees with the improved semi-analytic model of hierarchical structure\nformation of Tonini et al. (2012), which predicts star-forming BCGs throughout\nthe epoch considered. We attribute the star formation inferred from the stacked\ninfrared SEDs to both major and minor 'wet' (gas-rich) mergers, based on a lack\nof key signatures (to date) of the cluster cooling flows to which BCG star\nformation is typically attributed, as well as a number of observational and\nsimulation-based studies that support this scenario." }, { "anchor": "Star formation conditions in a Planck Galactic Cold Clump, G108.84-00.81: We present the results from a series of ground-based radio observations\ntoward a Planck Galactic Cold Clump (PGCC), PGCC G108.84-00.81, which is\nlocated in one curved filamentary cloud in the vicinity of an extended HII\nregion Sh2-152 and SNR G109.1-1.0. PGCC G108.84-00.81 is mainly composed of two\nclumps, \"G108-N\" and \"G108-S\". In the 850 micron dust continuum emission map,\nG108-N is shown as one component while G108-S is fragmented into four\ncomponents. There is no infrared source associated with G108-N while there are\ntwo infrared sources (IRS 1 and IRS 2) associated with G108-S. The total mass\nof G108-N is larger than the jeans mass, suggesting that G108-N is\ngravitationally unstable and a potential place for a future star formation. The\nclump properties of G108-N and G108-S such as the gas temperature and the\ncolumn density, are not distinctly different. However, G108-S is slightly more\nevolved than G108-N, in the consideration of the CO depletion factor, molecular\nabundances, and association with infrared sources. G108-S seems to be affected\nby the compression from Sh2-152, while G108-N is relatively protected from the\nexternal effect", "positive": "The first comprehensive Milky Way stellar mock catalogue for the Chinese\n Space Station Telescope Survey Camera: The Chinese Space Station Telescope (CSST) is a cutting-edge two-meter\nastronomical space telescope currently under construction. Its primary Survey\nCamera (SC) is designed to conduct large-area imaging sky surveys using a\nsophisticated seven-band photometric system. The resulting data will provide\nunprecedented data for studying the structure and stellar populations of the\nMilky Way. To support the CSST development and scientific projects related to\nits survey data, we generate the first comprehensive Milky Way stellar mock\ncatalogue for the CSST SC photometric system using the TRILEGAL stellar\npopulation synthesis tool. The catalogue includes approximately 12.6 billion\nstars, covering a wide range of stellar parameters, photometry, astrometry, and\nkinematics, with magnitude reaching down to $g\\,=\\,27.5$ mag in the AB\nmagnitude system. The catalogue represents our benchmark understanding of the\nstellar populations in the Milky Way, enabling a direct comparison with the\nfuture CSST survey data. Particularly, it sheds light on faint stars that are\nhidden from current sky surveys. Our crowding limit analysis based on this\ncatalogue provides compelling evidence for the extension of the CSST Optical\nSurvey (OS) to cover low Galactic latitude regions. The strategic extension of\nthe CSST-OS coverage, combined with this comprehensive mock catalogue, will\nenable transformative science with the CSST." }, { "anchor": "Radio-Quiet Quasars in the VIDEO Survey: Evidence for AGN-powered radio\n emission at S_1.4GHz < 1 mJy: Understanding the interplay between black-hole accretion and star formation,\nand how to disentangle the two, is crucial to our understanding of galaxy\nformation and evolution. To investigate, we use a combination of optical and\nnear-infrared photometry to select a sample of 74 quasars from the VISTA Deep\nExtragalactic Observations (VIDEO) Survey, over 1 deg$^2$. The depth of VIDEO\nallows us to study very low accretion rates and/or lower-mass black holes, and\n26 per cent of the candidate quasar sample has been spectroscopically\nconfirmed. We use a radio-stacking technique to sample below the nominal\nflux-density threshold using data from the Very Large Array at 1.4 GHz and\nfind, in agreement with other work, that a power-law fit to the quasar-related\nradio source counts is inadequate at low flux density. By comparing with a\ncontrol sample of galaxies (where we match in terms of stellar mass), and by\nestimating the star formation rate, we suggest that this radio emission is\npredominantly caused by accretion activity rather than star-formation activity.", "positive": "Orbits of Massive Satellite Galaxies: I. A Close Look at the Large\n Magellanic Cloud and a New Orbital History for M33: The Milky Way (MW) and M31 both harbor massive satellite galaxies, the Large\nMagellanic Cloud (LMC) and M33, which may comprise up to 10 per cent of their\nhost's total mass. Massive satellites can change the orbital barycentre of the\nhost-satellite system by tens of kiloparsecs and are cosmologically expected to\nharbor dwarf satellite galaxies of their own. Assessing the impact of these\neffects depends crucially on the orbital histories of the LMC and M33. Here, we\nrevisit the dynamics of the MW-LMC system and present the first detailed\nanalysis of the M31-M33 system utilizing high precision proper motions and\nstatistics from the dark matter-only Illustris cosmological simulation. With\nthe latest Hubble Space Telescope proper motion measurements of M31, we\nreliably constrain M33's interaction history with its host. In particular, like\nthe LMC, M33 is either on its first passage (t_{inf} < 2 Gyr ago) or if M31 is\nmassive (>=2x10^12 Msun), it is on a long period orbit of about 6 Gyr.\nCosmological analogs of the LMC and M33 identified in Illustris support this\npicture and provide further insight about their host masses. We conclude that,\ncosmologically, massive satellites like the LMC and M33 are likely completing\ntheir first orbits about their hosts. We also find that the orbital energies of\nsuch analogs prefer a MW halo mass ~1.5x10^12 Msun and an M31 halo mass\n>=1.5x10^12 Msun. Despite conventional wisdom, we conclude it is highly\nimprobable that M33 made a close (< 100 kpc) approach to M31 recently (\nt_{peri} < 3 Gyr ago). Such orbits are rare (< 1 per cent) within the 4$\\sigma$\nerror space allowed by observations. This conclusion cannot be explained by\nperturbative effects through four body encounters between the MW, M31, M33, and\nthe LMC. This surprising result implies that we must search for a new\nexplanation for M33's strongly warped gas and stellar discs." }, { "anchor": "The Spatial Distribution of Satellite Galaxies Selected from Redshift\n Space: We investigate the spatial distribution of satellite galaxies using a mock\nredshift survey of the first Millennium Run simulation. The satellites were\nidentified using common redshift space criteria and the sample therefore\nincludes a large percentage of interlopers. The satellite locations are\nwell-fitted by a combination of a Navarro, Frenk & White(NFW) density profile\nand a power law. At fixed stellar mass, the NFW scale parameter, r_s, for the\nsatellite distribution of red hosts exceeds r_s for the satellite distribution\nof blue hosts. In both cases the dependence of r_s on host stellar mass is\nwell-fitted by a power law. For the satellites of red hosts, r_s^{red} \\propto\n(M_\\ast / M_\\sun)^{0.71 \\pm 0.05} while for the satellites of blue hosts,\nr_s^{blue} \\propto (M_\\ast / M_\\sun)^{0.48 \\pm 0.07}$. For hosts with stellar\nmasses greater than 4.0E+10 M_sun, the satellite distribution around blue hosts\nis more concentrated than is the satellite distribution around red hosts. The\nspatial distribution of the satellites of red hosts traces that of the hosts'\nhalos; however, the spatial distribution of the satellites of blue hosts is\nmore concentrated than that of the hosts' halos by a factor of ~2. Our\nmethodology is general and applies to any analysis of satellites in a mock\nredshift survey. However, our conclusions necessarily depend upon the\nsemi-analytic galaxy formation model that was adopted, and different galaxy\nformation models may yield different results.", "positive": "Local Universe Science with the E-ELT: This paper briefly reviews some of the exciting studies of the local Universe\nthat will be enabled with the European Extremely Large Telescope (E-ELT). As\nillustrative examples, it summarizes a few of the scientific goals that have\nbeen set for this instrument for studies of young starburst clusters, evolved\nstars, the Galactic centre, Galactic structure, nucleo-chronometry, the\ninterpretation of the \"Spite Plateau,\" and the properties of resolved stellar\npopulations in external galaxies. It finishes on a note of warning that we\nreally need to be even more innovative and adventurous if we are to justify the\ncost of the E-ELT." }, { "anchor": "The Discovery of Gas-Rich, Dusty Starbursts in Luminous Reddened Quasars\n at $z\\sim2.5$ with ALMA: We present ALMA observations of cold dust and molecular gas in four\nhigh-luminosity, heavily reddened (A$_{\\rm{V}} \\sim 2.5-6$ mag) Type 1 quasars\nat $z\\sim2.5$ with virial M$_{\\rm{BH}} \\sim 10^{10}$M$_\\odot$, to test whether\ndusty, massive quasars represent the evolutionary link between submillimetre\nbright galaxies (SMGs) and unobscured quasars. All four quasars are detected in\nboth the dust continuum and in the $^{12}$CO(3-2) line. The mean dust mass is\n6$\\times$10$^{8}$M$_\\odot$ assuming a typical high redshift quasar spectral\nenergy distribution (T=41K, $\\beta$=1.95 or T=47K, $\\beta$=1.6). The implied\nstar formation rates are very high - $\\gtrsim$1000 M$_\\odot$ yr$^{-1}$ in all\ncases. Gas masses estimated from the CO line luminosities cover\n$\\sim$1-5$\\times10^{10}$($\\alpha_{\\rm{CO}} / 0.8$)M$_\\odot$ and the gas\ndepletion timescales are very short - $\\sim5-20$Myr. A range of gas-to-dust\nratios is observed in the sample. We resolve the molecular gas in one quasar -\nULASJ2315$+$0143 ($z=2.561$) - which shows a strong velocity gradient over\n$\\sim$20 kpc. The velocity field is consistent with a rotationally supported\ngas disk but other scenarios, e.g. mergers, cannot be ruled out at the current\nresolution of these data. In another quasar - ULASJ1234+0907 ($z=2.503$) - we\ndetected molecular line emission from two millimetre bright galaxies within 200\nkpc of the quasar, suggesting that this quasar resides in a significant\nover-density. The high detection rate of both cold dust and molecular gas in\nthese sources, suggests that reddened quasars could correspond to an early\nphase in massive galaxy formation associated with large gas reservoirs and\nsignificant star formation.", "positive": "Scale-invariant Mode in Collisionless Spherical Stellar Systems: An analytical solution of the perturbed equations is obtained, which exists\nin all ergodic models of collisionless spherical stellar systems with a single\nlength parameter. This solution corresponds to variations of this parameter,\ni.e., stretching or shrinking the sphere while preserving the total mass. The\nsystem remains in an equilibrium state. The simplicity of the solution allows\nfor explicit expressions for the distribution function, potential, and density\nat all orders of perturbation theory. This, in turn, helps to clarify the\nconcept of perturbation energy, which, being a second-order quantity in\namplitude, cannot be calculated in linear theory. It is shown that the correct\nexpression for perturbation energy, constructed taking into account 2nd order\nperturbations, and the well-known expression for perturbation energy\nconstructed as bilinear form obtained within linear theory from 1st order\nperturbations do not coincide. However, both of these energies are integrals of\nmotion and differ only by a constant. The obtained solution can be used to\ncontrol the correctness of codes and the accuracy of calculations in the\nnumerical study of collisionless stellar models." }, { "anchor": "2018 Census of Interstellar, Circumstellar, Extragalactic,\n Protoplanetary Disk, and Exoplanetary Molecules: To date, 204 individual molecular species, comprised of 16 different\nelements, have been detected in the interstellar and circumstellar medium by\nastronomical observations. These molecules range in size from two atoms to\nseventy, and have been detected across the electromagnetic spectrum from\ncm-wavelengths to the ultraviolet. This census presents a summary of the first\ndetection of each molecular species, including the observational facility,\nwavelength range, transitions, and enabling laboratory spectroscopic work, as\nwell as listing tentative and disputed detections. Tables of molecules detected\nin interstellar ices, external galaxies, protoplanetary disks, and exoplanetary\natmospheres are provided. A number of visual representations of this aggregate\ndata are presented and briefly discussed in context.", "positive": "The Nature of LoBAL QSOs: II. HST/WFC3 Observations Reveal Host Galaxies\n Dominated by Mergers: Low-ionization Broad Absorption Line QSOs (LoBALs) are suspected to be\nmerging systems in which extreme, AGN-driven outflows have been triggered.\nWhether or not LoBALs are uniquely associated with mergers, however, has yet to\nbe established. To characterize the morphologies of LoBALs, we present the\nfirst high-resolution morphological analysis of a volume-limited sample of 22\nSDSS-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field\nCamera 3 observations. Host galaxies are resolved in 86% of the systems in\nF125W, which is sensitive to old stellar populations, while only 18% are\ndetected in F475W, which traces young, unobscured stellar populations. Signs of\nrecent or ongoing tidal interaction are present in 45-64% of the hosts,\nincluding double nuclei, tidal tails, bridges, plumes, shells, and extended\ndebris. Ongoing interaction with a companion is apparent in 27-41% of the\nLoBALs, with as much as 1/3 of the sample representing late-stage mergers at\nprojected nuclear separations <10 kpc. Detailed surface brightness modeling\nindicates that 41% of the hosts are bulge-dominated while only 18% are disks.\nWe discuss trends in various properties as a function of merger stage and\nparametric morphology. Notably, mergers are associated with slower, dustier\nwinds than those seen in undisturbed/unresolved hosts. Our results favor an\nevolutionary scenario in which quasar-level accretion during various merger\nstages is associated with the observed outflows in low-z LoBALs. We discuss\ndifferences between LoBALs and FeLoBALs and show that selection via the\ntraditional Balnicity index would have excluded all but one of the mergers." }, { "anchor": "Secondary radiation from the Pamela/ATIC excess and relevance for Fermi: The excess of electrons/positrons observed by the Pamela and ATIC experiments\ngives rise to a noticeable amount of synchrotron and Inverse Compton Scattering\n(ICS) radiation when the e^+e^- interact with the Galactic Magnetic Field, and\nthe InterStellar Radiation Field (ISRF). In particular, the ICS signal produced\nwithin the WIMP annihilation interpretation of the Pamela/ATIC excess shows\nalready some tension with the EGRET data. On the other hand, 1 yr of Fermi data\ntaking will be enough to rule out or confirm this scenario with a high\nconfidence level. The ICS radiation produces a peculiar and clean \"ICS Haze\"\nfeature, as well, which can be used to discriminate between the astrophysical\nand Dark Matter scenarios. This ICS signature is very prominent even several\ndegrees away from the galactic center, and it is thus a very robust prediction\nwith respect to the choice of the DM profile and the uncertainties in the ISRF.", "positive": "High resolution elemental abundance analysis of the Hyades Supercluster: The existence of a kinematically defined moving group of stars centred at U =\n-40, V = -17 km/s referred to as the Hyades Supercluster, has been suggested as\nthe debris of an originally large star forming event, with its core being the\npresent day Hyades open cluster. Using high-resolution UVES spectra, we present\nelemental abundances for a range of alpha, Fe-peak and neutron-capture elements\nfor 26 proposed supercluster stars. Our results show that the sample stars\ndisplay a heterogeneous abundance distribution, with a clump around [Fe/H] =\n+0.15. We also calculate stellar radial velocities and U,V,W space velocities.\nEnforcing a strict chemical and kinematical membership criteria, we find 4\nsupercluster stars share the Hyades open cluster abundances and kinematics,\nwhile many of the remaining stars fit the disc field kinematics and abundance\nrange. We discuss our findings in the context of the Hyades supercluster being\na dispersed star-forming remnant, a stellar stream of purely dynamical origin\nor a result of several processes." }, { "anchor": "A Green Pea starburst arising from a galaxy-galaxy merger: Green Pea galaxies are low-redshift starburst dwarf galaxies, with properties\nsimilar to those of the high-redshift galaxies that reionized the Universe. We\nreport the first mapping of the spatial distribution of atomic hydrogen (HI) in\nand around a Green Pea, GP J0213+0056 at z=0.0399, using the Giant Metrewave\nRadio Telescope (GMRT). Like many Green Peas, GP J0213+0056 shows strong HI 21\ncm emission in single-dish spectroscopy, strong Ly-alpha emission, and a high\n[OIII]$\\lambda$5007/[OIII]$\\lambda$3727 luminosity ratio, O32 $\\approx$ 8.8,\nconsistent with a high leakage of Lyman-continuum radiation. Our GMRT HI 21 cm\nimages show that the HI 21 cm emission in the field of GP J0213+0056 arises\nfrom an extended broken-ring structure around the Green Pea, with the strongest\nemission coming from a region between GP J0213+0056 and a companion galaxy\nlying $\\approx$ 4.7 kpc away, and little HI 21cm emission coming from the Green\nPea itself. We find that the merger between GP J0213+0056 and its companion is\nlikely to have triggered the starburst, and led to a disturbed HI spatial and\nvelocity distribution, which in turn allowed Ly-alpha (and, possibly,\nLyman-continuum) emission to escape the Green Pea. Our results suggest that\nsuch mergers, and the resulting holes in the HI distribution, are a natural way\nto explain the tension between the requirements of cold gas to fuel the\nstarburst and the observed leakage of Ly-alpha and Lyman-continuum emission in\nGreen Pea galaxies and their high-redshift counterparts.", "positive": "Hybrid photometric redshifts for sources in the COSMOS and XMM-LSS\n fields: In this paper we present photometric redshifts for 2.7 million galaxies in\nthe XMM-LSS and COSMOS fields, both with rich optical and near-infrared data\nfrom VISTA and HyperSuprimeCam. Both template fitting (using galaxy and Active\nGalactic Nuclei templates within LePhare) and machine learning (using GPz)\nmethods are run on the aperture photometry of sources selected in the Ks-band.\nThe resulting predictions are then combined using a Hierarchical Bayesian\nmodel, to produce consensus photometric redshift point estimates and\nprobability distribution functions that outperform each method individually.\nOur point estimates have a root mean square error of ~0.08-0.09, and an outlier\nfraction of ~3-4 percent when compared to spectroscopic redshifts. We also\ncompare our results to the COSMOS2020 photometric redshifts, which contains\nfewer sources, but had access to a larger number of bands and greater\nwavelength coverage, finding that comparable photo-z quality can be achieved\n(for bright and intermediate luminosity sources where a direct comparison can\nbe made). Our resulting redshifts represent the most accurate set of\nphotometric redshifts (for a catalogue this large) for these deep multi-square\ndegree multi-wavelength fields to date." }, { "anchor": "Observed trend in the star formation history and the dark matter\n fraction of galaxies at redshift $z\\approx0.8$: We study the star formation history for a sample of 154 galaxies with stellar\nmass $10^{10}\\lesssim M_{\\ast}\\lesssim 10^{12} M_{\\odot}$ in the redshift range\n$0.7 < z < 0.9$. We do this using stellar population models combined with\nfull-spectrum fitting of good quality spectra and high resolution photometry.\nFor a subset of 68 galaxies ($M_{\\ast}\\gtrsim 10^{11} M_{\\odot}$) we\nadditionally construct dynamical models. These use an axisymmetric solution to\nthe Jeans equations, which allows for velocity anisotropy, and adopts results\nfrom abundance matching techniques to account for the dark matter content.\n We find that: (i) The trends in star formation history observed in the local\nuniverse are already in place by $z\\sim1$: the most massive galaxies are\nalready passive, while lower mass ones have a more extended star formation\nhistories, and the lowest mass galaxies are actively forming stars; (ii) we\nplace an upper limit of a factor 1.5 to the size growth of the massive galaxy\npopulation; (iii) we present strong evidence for low dark matter fractions\nwithin $1R_{\\rm e}$ (median of 9 per cent and 90th percentile of 21 per cent)\nfor galaxies with $M_{\\ast} \\gtrsim 10^{11} M_{\\odot}$ at these redshifts; and\n(iv) we confirm that these galaxies have, on average, a Salpeter normalisation\nof the stellar initial mass function.", "positive": "HST/COS Observations of Quasar Outflows in the 500 -- 1050 \u00c5 Rest\n Frame: II The Most Energetic Quasar Outflow Measured to Date: We present a study of the BAL outflows seen in quasar SDSS J1042+1646 (z =\n0.978) in the rest-frame 500 -- 1050 $\\r{A}$ (EUV500) region. The results are\nbased on the analysis of recent Hubble Space Telescope/Cosmic Origins\nSpectrograph observations. Five outflow systems are identified, where in total\nthey include $\\sim$70 outflow troughs from ionic transitions. These include the\nfirst non-solar detections from transitions of O V*, Ne V*, Ar VI, Ca VI, Ca\nVII, and Ca VIII. The appearance of very high-ionization species (e.g., Ne\nVIII, Na IX, and Mg X) in all outflows necessitates at least two-ionization\nphases for the observed outflows. We develop an interactive Synthetic Spectral\nSimulation method to fit the multitude of observed troughs. Detections of\ndensity sensitive troughs (e.g., S IV* $\\lambda$ 657.32 $\\r{A}$ and the O V*\nmultiplet) allow us to determine the distance of the outflows ($R$) as well as\ntheir energetics. Two of the outflows are at $R$ $\\simeq$ 800 pc and one is at\n$R$ $\\simeq$ 15 pc. One of the outflows has the highest kinetic luminosity on\nrecord ($\\dot{E_{k}}$ $ = 5\\times 10^{46}$ erg s$^{-1}$), which is 20% of its\nEddington luminosity. Such a large ratio suggests that this outflow can provide\nthe energy needed for active galactic nucleus feedback mechanisms." }, { "anchor": "Evidence for an InterMediate Line Region in AGN's Inner Torus Region and\n Its Evolution from Narrow to Broad Line Seyfert I Galaxies: We have decomposed the broad H-alpha, H-beta and H-gamma lines of 90 Active\nGalactic Nuclei (AGNs) into a superposition of a very broad and an intermediate\nGaussian components (VBGC and IMGC) and discovered that the two Gaussian\ncomponents evolve with FWHM of the whole emission lines. We suggest that the\nVBGC and the IMGC are produced in different emission regions, namely, Very\nBroad Line Region (VBLR) and Intermediate Line Region (IMLR). The details of\nthe two components of H-alpha, H-beta and H-gamma lines indicate that the\nradius obtained from the emission line reverberation mapping normally\ncorresponds to the radius of the VBLR, but the radius obtained from the\ninfrared reverberation mapping corresponding to IMLR, i.e., the inner boundary\nof the dusty torus. The existence of the IMGC may affect the measurement of the\nblack hole mass in AGNs. Therefore, the deviation of NLS1s from the M-sigma\nrelation may be explained naturally in this way. The evolution of the two\nemission line regions may be related to the evolutionary stages of the broad\nline regions of AGNs from NLS1s to BLS1s. Other evidences for the existence of\nthe IMLR are also presented.", "positive": "Environmental effects on associations of dwarf galaxies: We study the properties of associations of dwarf galaxies and their\ndependence on the environment. Associations of dwarf galaxies are extended\nsystems composed exclusively of dwarf galaxies, considering as dwarf galaxies\nthose galaxies less massive than $M_{\\star, \\rm max} = 10^{9.0}$ ${\\rm\nM}_{\\odot}\\,h^{-1}$. We identify these particular systems using a\nsemi-analytical model of galaxy formation coupled to a dark matter only\nsimulation in the $\\Lambda$ Cold Dark Matter cosmological model. To classify\nthe environment, we estimate eigenvalues from the tidal field of the dark\nmatter particle distribution of the simulation. We find that the majority, two\nthirds, of associations are located in filaments ($ \\sim 67$ per cent),\nfollowed by walls ($ \\sim 26 $ per cent), while only a small fraction of them\nare in knots ($ \\sim 6 $ per cent) and voids ($ \\sim 1 $ per cent).\nAssociations located in more dense environments present significantly higher\nvelocity dispersion than those located in less dense environments, evidencing\nthat the environment plays a fundamental role in their dynamical properties.\nHowever, this connection between velocity dispersion and the environment\ndepends exclusively on whether the systems are gravitational bound or unbound,\ngiven that it disappears when we consider associations of dwarf galaxies that\nare gravitationally bound. Although less than a dozen observationally detected\nassociations of dwarf galaxies are currently known, our results are predictions\non the eve of forthcoming large surveys of galaxies, which will enable these\nvery particular systems to be identified and studied." }, { "anchor": "Solo dwarfs IV: Comparing and contrasting satellite and isolated dwarf\n galaxies in the Local Group: We compare and contrast the stellar structures of isolated Local Group dwarf\ngalaxies, as traced by their oldest stellar populations, with the satellite\ndwarf galaxies of the Milky Way and M31. All Local Group dwarfs with Mv < -6\nand surface brightness < 26.5 mags. per square arcsec. are considered, taking\nadvantage of measurements from surveys that use similar observations and\nanalysis techniques. For the isolated dwarfs, we use the results from Solitary\nLocal (Solo) Dwarf Galaxy Survey. We begin by confirming that the structural\nand dynamical properties of the two satellite populations are not obviously\nstatistically different from each other, but we note that there many more\nsatellites around M31 than around the Milky Way down to equivalent magnitude\nand surface brightness limits. We find that dwarfs in close proximity to a\nmassive galaxy generally show more scatter in their Kormendy relations than\nthose in isolation. Specifically, isolated Local Group dwarf galaxies show a\ntighter trend of half-light radius versus magnitude than the satellite\npopulations, and similar effects are also seen for related parameters. There\nappears to be a transition in the structural and dynamical properties of the\ndwarf galaxy population around ~400 kpc from the Milky Way and M31, such that\nthe smallest, faintest, most circular dwarf galaxies are found closer than this\nseparation. We discuss the impact of selection effects on our analysis, and we\nargue that our results point to the significance of tidal interactions on the\npopulation of systems within approximately 400 kpc from the MW and M31.", "positive": "Direct T_e-based Metallicities of z=2-9 Galaxies with JWST/NIRSpec:\n Empirical Metallicity Calibrations Applicable from Reionization to Cosmic\n Noon: We report detections of the [OIII]$\\lambda$4364 auroral emission line for 16\ngalaxies at z=2.1-8.7, measured from JWST/NIRSpec observations obtained as part\nof the Cosmic Evolution Early Release Science (CEERS) survey program. We\ncombine this CEERS sample with 9 objects from the literature at z=4-9 with\nauroral-line detections from JWST/NIRSpec and 21 galaxies at z=1.4-3.7 with\nauroral-line detections from ground-based spectroscopy. We derive electron\ntemperature T_e and direct-method oxygen abundances for the combined sample of\n46 star-forming galaxies at z=1.4-8.7. We use these measurements to construct\nthe first high-redshift empirical T_e-based metallicity calibrations for the\nstrong-line ratios [OIII]/H$\\beta$, [OII]/H$\\beta$,\nR23=([OIII]+[OII])/H$\\beta$, [OIII]/[OII], and [NeIII]/[OII]. These new\ncalibrations are valid over 12+log(O/H)=7.0-8.4 and can be applied to samples\nof star-forming galaxies at z=2-9, leading to an improvement in the accuracy of\nmetallicity determinations at Cosmic Noon and in the Epoch of Reionization. The\nhigh-redshift strong-line relations are offset from calibrations based on\ntypical $z\\sim0$ galaxies or HII regions, reflecting the known evolution of\nionization conditions between $z\\sim0$ and $z\\sim2$. Deep spectroscopic\nprograms with JWST/NIRSpec promise to improve statistics at the low and high\nends of the metallicity range covered by the current sample, as well as improve\nthe detection rate of [NII]$\\lambda$6585 to allow the future assessment of\nN-based indicators. These new high-redshift calibrations will enable accurate\ncharacterizations of metallicity scaling relations at high redshift, improving\nour understanding of feedback and baryon cycling in the early universe." }, { "anchor": "Measuring magnetism in the Milky Way with the Square Kilometre Array: Magnetic fields in the Milky Way are present on a wide variety of sizes and\nstrengths, influencing many processes in the Galactic ecosystem such as star\nformation, gas dynamics, jets, and evolution of supernova remnants or pulsar\nwind nebulae. Observation methods are complex and indirect; the most used of\nthese are a grid of rotation measures of unresolved polarized extragalactic\nsources, and broadband polarimetry of diffuse emission. Current studies of\nmagnetic fields in the Milky Way reveal a global spiral magnetic field with a\nsignificant turbulent component; the limited sample of magnetic field\nmeasurements in discrete objects such as supernova remnants and HII regions\nshows a wide variety in field configurations; a few detections of magnetic\nfields in Young Stellar Object jets have been published; and the magnetic field\nstructure in the Galactic Center is still under debate.\n The SKA will unravel the 3D structure and configurations of magnetic fields\nin the Milky Way on sub-parsec to galaxy scales, including field structure in\nthe Galactic Center. The global configuration of the Milky Way disk magnetic\nfield, probed through pulsar RMs, will resolve controversy about reversals in\nthe Galactic plane. Characteristics of interstellar turbulence can be\ndetermined from the grid of background RMs. We expect to learn to understand\nmagnetic field structures in protostellar jets, supernova remnants, and other\ndiscrete sources, due to the vast increase in sample sizes possible with the\nSKA. This knowledge of magnetic fields in the Milky Way will not only be\ncrucial in understanding of the evolution and interaction of Galactic\nstructures, but will also help to define and remove Galactic foregrounds for a\nmultitude of extragalactic and cosmological studies.", "positive": "Confirmation of Enhanced Long Wavelength Dust Emission in OMC 2/3: Previous continuum observations from the MUSTANG camera on the Green Bank\nTelescope (GBT) of the nearby star-forming filament OMC 2/3 found elevated\nemission at 3.3 mm relative to shorter wavelength data. As a consequence, the\ninferred dust emissivity index obtained from modified black body dust spectra\nwas considerably lower than what is typically measured on $\\sim 0.1 \\, {\\rm\npc}$ scales in nearby molecular clouds. Here we present new observations of OMC\n2/3 collected with the MUSTANG-2 camera on the GBT which confirm this elevated\nemission. We also present for the first time sensitive 1 cm observations made\nwith the Ka-band receiver on the GBT which also show higher than expected\nemission. We use these observations--- along with Herschel, JCMT, Mambo, and\nGISMO data--- to assemble spectral energy distributions (SEDs) of a variety of\nstructures in OMC 2/3 spanning the range $160 \\, {\\rm \\mu m}$ to $1 \\, {\\rm\ncm}$. The data at 2 mm and shorter are generally consistent with a modified\nblack body spectrum and a single value of $\\beta \\sim 1.6$. The 3 mm and 1 cm\ndata, however, lie well above such an SED. The spectrum of the long wavelength\nexcess is inconsistent with both free-free emission and standard \"Spinning\nDust\" models for Anomalous Microwave Emission (AME). The 3 mm and 1 cm data\ncould be explained by a flatter dust emissivity at wavelengths shorter than 2\nmm, potentially in concert with AME in some regions." }, { "anchor": "Scaling for the intensity of radiation in spherical and aspherical\n planetary nebulae: The image of planetary nebulae is made by three different physical processes.\nThe first process is the expansion of the shell that can be modeled by the\ncanonical laws of motion in the spherical case and by the momentum conservation\nwhen gradients of density are present in the interstellar medium. The second\nprocess is the diffusion of particles that radiate from the advancing layer.\nThe 3D diffusion from a sphere as well as the 1D diffusion with drift are\nanalyzed. The third process is the composition of the image through an integral\noperation along the line of sight. The developed framework is applied to A39,\nto the Ring nebula and to the etched hourglass nebula MyCn 18.", "positive": "A highly-ionized region surrounding SN Refsdal revealed by MUSE: Supernova (SN) Refsdal is the first multiply-imaged, highly-magnified, and\nspatially-resolved SN ever observed. The SN exploded in a highly-magnified\nspiral galaxy at z=1.49 behind the Frontier Fields Cluster MACS1149, and\nprovides a unique opportunity to study the environment of SNe at high z. We\nexploit the time delay between multiple images to determine the properties of\nthe SN and its environment, before, during, and after the SN exploded. We use\nthe integral-field spectrograph MUSE on the VLT to simultaneously target all\nobserved and model-predicted positions of SN Refsdal. We find MgII emission at\nall positions of SN Refsdal, accompanied by weak FeII* emission at two\npositions. The measured ratios of [OII] to MgII emission of 10-20 indicate a\nhigh degree of ionization with low metallicity. Because the same high degree of\nionization is found in all images, and our spatial resolution is too coarse to\nresolve the region of influence of SN Refsdal, we conclude that this high\ndegree of ionization has been produced by previous SNe or a young and hot\nstellar population. We find no variability of the [OII] line over a period of\n57 days. This suggests that there is no variation in the [OII] luminosity of\nthe SN over this period, or that the SN has a small contribution to the\nintegrated [OII] emission over the scale resolved by our observations." }, { "anchor": "The X-ray and Mid-Infrared luminosities in Luminous Type 1 Quasars: Several recent studies have reported different intrinsic correlations between\nthe AGN mid-IR luminosity ($L_{MIR}$) and the rest-frame 2-10 keV luminosity\n($L_{X}$) for luminous quasars. To understand the origin of the difference in\nthe observed $L_{X}-L_{MIR}$ relations, we study a sample of 3,247\nspectroscopically confirmed type 1 AGNs collected from Bo\\\"{o}tes, XMM-COSMOS,\nXMM-XXL-North, and the SDSS quasars in the Swift/XRT footprint spanning over\nfour orders of magnitude in luminosity. We carefully examine how different\nobservational constraints impact the observed $L_{X}-L_{MIR}$ relations,\nincluding the inclusion of X-ray non-detected objects, possible X-ray\nabsorption in type 1 AGNs, X-ray flux limits, and star formation contamination.\nWe find that the primary factor driving the different $L_{X}-L_{MIR}$ relations\nreported in the literature is the X-ray flux limits for different studies. When\ntaking these effects into account, we find that the X-ray luminosity and mid-IR\nluminosity (measured at rest-frame $6\\mu m$, or $L_{6\\mu m}$) of our sample of\ntype 1 AGNs follow a bilinear relation in the log-log plane: $\\log L_X\n=(0.84\\pm0.03)\\times\\log L_{6\\mu m}/10^{45}{\\rm erg\\;s^{-1}} + (44.60\\pm0.01)$\nfor $L_{6\\mu m} < 10^{44.79}{\\rm erg\\;s^{-1}} $, and $\\log L_X =\n(0.40\\pm0.03)\\times\\log L_{6\\mu m}/10^{45}{\\rm erg\\;s^{-1}} +(44.51\\pm0.01)$\nfor $L_{6\\mu m} \\geq 10^{44.79}{\\rm erg\\;s^{-1}} $. This suggests that the\nluminous type 1 quasars have a shallower $L_{X}-L_{MIR}$ correlation than the\napproximately linear relations found in local Seyfert galaxies. This result is\nconsistent with previous studies reporting a luminosity-dependent\n$L_{X}-L_{MIR}$ relation, and implies that assuming a linear $L_{X}-L_{MIR}$\nrelation to infer the neutral gas column density for X-ray absorption might\noverestimate the column densities in luminous quasars.", "positive": "The Bolocam Galactic Plane Survey IV: 1.1 and 0.35 mm Dust Continuum\n Emission in the Galactic Center Region: The Bolocam Galactic Plane Survey (BGPS) data for a six square degree region\nof the Galactic plane containing the Galactic center is analyzed and compared\nto infrared and radio continuum data. The BGPS 1.1 mm emission consists of\nclumps interconnected by a network of fainter filaments surrounding cavities, a\nfew of which are filled with diffuse near-IR emission indicating the presence\nof warm dust or with radio continuum characteristic of HII regions or supernova\nremnants. New 350 {\\mu}m images of the environments of the two brightest\nregions, Sgr A and B, are presented. Sgr B2 is the brightest mm-emitting clump\nin the Central Molecular Zone and may be forming the closest analog to a super\nstar cluster in the Galaxy. The Central Molecular Zone (CMZ) contains the\nhighest concentration of mm and sub-mm emitting dense clumps in the Galaxy.\nMost 1.1 mm features at positive longitudes are seen in silhouette against the\n3.6 to 24 {\\mu}m background observed by the Spitzer Space Telescope. However,\nonly a few clumps at negative longitudes are seen in absorption, confirming the\nhypothesis that positive longitude clumps in the CMZ tend to be on the\nnear-side of the Galactic center, consistent with the suspected orientation of\nthe central bar in our Galaxy. Some 1.1 mm cloud surfaces are seen in emission\nat 8 {\\mu}m, presumably due to polycyclic aromatic hydrocarbons (PAHs). A\n~0.2\\degree (~30 pc) diameter cavity and infrared bubble between l \\approx\n0.0\\degree and 0.2\\degree surrounds the Arches and Quintuplet clusters and Sgr\nA. The bubble contains several clumpy dust filaments that point toward Sgr\nA\\ast; its potential role in their formation is explored. [abstract truncated]" }, { "anchor": "The survival of globular clusters in a cuspy Fornax: It has long been argued that the radial distribution of globular clusters\n(GCs) in the Fornax dwarf galaxy requires its dark matter halo to have a core\nof size $\\sim 1$ kpc. We revisit this argument by investigating analogues of\nFornax formed in E-MOSAICS, a cosmological hydrodynamical simulation that\nself-consistently follows the formation and evolution of GCs in the EAGLE\ngalaxy formation model. In EAGLE, Fornax-mass haloes are cuspy and well\ndescribed by the Navarro-Frenk-White profile. We post-process the E-MOSAICS to\naccount for GC orbital decay by dynamical friction, which is not included in\nthe original model. Dynamical friction causes 33 per cent of GCs with masses\n$M_{\\rm GC}\\geq4\\times10^4 {~\\rm M_\\odot}$ to sink to the centre of their host\nwhere they are tidally disrupted. Fornax has a total of five GCs, an\nexceptionally large number compared to other galaxies of similar stellar mass.\nIn the simulations, we find that only 3 per cent of the Fornax analogues have\nfive or more GCs, while 30 per cent have only one and 35 per cent have none. We\nfind that GC systems in satellites are more centrally concentrated than in\nfield dwarfs, and that those formed in situ (45 per cent) are more concentrated\nthan those that were accreted. The survival probability of a GC increases\nrapidly with the radial distance at which it formed ($r_{\\rm init}$): it is 37\nper cent for GCs with $r_{\\rm init} \\leq 1$ kpc and 92 per cent for GCs with\n$r_{\\rm init} \\geq 1$ kpc. The present-day radial distribution of GCs in\nE-MOSAICS turns out to be indistinguishable from that in Fornax, demonstrating\nthat, contrary to claims in the literature, the presence of five GCs in the\ncentral kiloparsec of Fornax does not exclude a cuspy DM halo.", "positive": "Modeling the JWST high-redshift galaxies with a general formation\n scenario and the consistency with the $\u039b$CDM model: Early results from the James Webb Space Telescope (JWST) observations have\nhinted at two traces beyond the standard cosmological framework. One is the\nextraordinarily high stellar masses and their density at $z=7.5\\sim9.1$,\nanother is the unexpected abundance of ultraviolet (UV) bright galaxies at\n$z\\ge10$. Nevertheless, both pieces of evidence are not statistically robust\nyet. In this work, we construct rest-frame UV luminosity functions (LFs) based\non a general formation model for these high-redshift galaxy candidates, since\nUV LFs always carry the information of stellar formation efficiency (SFE),\ninitial mass function (IMF), dust attenuation, and other crucial elements for\ngalaxy evolution. By updating the massive galaxies candidates with\nspectroscopic observations and exploring the parameter space of SFE, we are\nable to reasonably explain the cumulative stellar mass density within the\nredshift range of $7.5\\sim9.1$, with only one galaxy exhibiting unusual\ncharacteristics. We also reveal a potential nonmonotonic trend of SFE with the\nincreasing redshift. At higher redshift ($z\\sim13$), bright UV LFs can be well\nfitted with non-dust attenuation or top-heavy IMF for Population III stars. The\nPopulation III star scenario can also naturally account for the possible dip of\nthe peak SFE evolution curve at $z\\sim9$." }, { "anchor": "An extended Lyman $\u03b1$ outflow from a radio galaxy at z=3.7?: Spatially resolved observations of AGN host galaxies undergoing feedback\nprocesses are one of the most relevant avenues through which galactic evolution\ncan be studied, given the long lasting effects AGN feedback has on gas\nreservoirs, star formation, and AGN environments at all scales. Within this\ncontext we report results from VLT/MUSE integral field optical spectroscopy of\nTN J1049-1258, one of the most powerful radio sources known, at a redshift of\n3.7. We detected extended ($\\sim$ 18 kpc) Lyman $\\alpha$ emission, spatially\naligned with the radio axis, redshifted by 2250 $\\pm$ 60 km s$^{-1}$ with\nrespect to the host galaxy systemic velocity, and co-spatial with UV continuum\nemission. This Lyman $\\alpha$ emission could arise from a companion galaxy,\nalthough there are arguments against this interpretation. Alternatively, it\nmight correspond to an outflow of ionized gas stemming from the radio galaxy.\nThe outflow would be the highest redshift spatially resolved ionized outflow to\ndate. The enormous amount of energy injected, however, appears to be unable to\nquench the host galaxy's prodigious star formation, occurring at a rate of\n$\\sim$4500 M$_{\\odot} yr^{-1}$, estimated using its far infra-red luminosity.\nWithin the field we also found two companion galaxies at projected distances of\n$\\sim$25 kpc and $\\sim$60 kpc from the host, which suggests the host galaxy is\nharbored within a protocluster.", "positive": "Two substructures in the nearby stellar halo found in Gaia and RAVE: We use the second Gaia data release (Gaia DR2), combined with RAVE\nspectroscopic surveys, to identify the substructures in the nearby stellar\nhalo. We select 3,845 halo stars kinematically and chemically, and determine\ntheir density distribution in energy and angular momentum space. To select the\nsubstructures from overdensities, we reshuffle the velocities and estimate\ntheir significance. Two statistically significant substructures, GR-1 and GR-2,\nare identified. GR-1 has a high binding energy and small $z$-angular momentum.\nGR-2 is metal-rich but retrograde. They are both new substructure, and may be\naccretion debris of dwarf galaxies." }, { "anchor": "Interpretation of Infrared Vibration-Rotation Spectra of Interstellar\n and Circumstellar Molecules: Infrared vibration-rotation lines can be valuable probes of interstellar and\ncircumstellar molecules, especially symmetric molecules, which have no pure\nrotational transitions. But most such observations have been interpreted with\nan isothermal absorbing slab model, which leaves out important radiative\ntransfer and molecular excitation effects. A more realistic non-LTE and\nnon-isothermal radiative transfer model has been constructed. The results of\nthis model are in much better agreement with the observations, including cases\nwhere lines in one branch of a vibration-rotation band are in absorption and\nanother in emission. In general, conclusions based on the isothermal absorbing\nslab model can be very misleading, but the assumption of LTE may not lead to\nsuch large errors, particularly if the radiation field temperature is close to\nthe gas temperature.", "positive": "The AMBRE Project: Origin and evolution of sulfur in the Milky Way: Sulfur is a volatile chemical element that plays an important role in tracing\nthe chemical evolution of galaxies. However, its nucleosynthesis origin and\nabundance variations are still unclear. The goal of the present article is to\naccurately and precisely study the S-content of large number of stars located\nin the solar neighbourhood. We use the parametrisation of thousands of HR\nstellar spectra provided by the AMBRE Project, and combine it with the\nautomated abundance determination GAUGUIN to derive LTE sulfur abundances for\n1855 slow-rotating FGK-type stars. This is the largest and most precise\ncatalogue of S-abundances published to date. It covers a metallicity domain as\nhigh as ~2.5dex starting at [M/H]~-2.0dex. We find that the [S/M] abundances\nratio is compatible with a plateau-like distribution in the metal-poor regime,\nand then starts to decrease continuously at [M/H]~-1.0dex. This decrease\ncontinues towards negative values for supersolar metallicity stars as recently\nreported for Mg and as predicted by Galactic chemical evolution models.\nMoreover, sulfur-rich stars having [M/H] in the range [-1.0,-0.5] have very\ndifferent kinematical and orbital properties with respect to more metal-rich\nand sulfur-poor ones. Two disc components, associated with the thin and thick\ndiscs, are thus seen independently in kinematics and sulfur abundances. The\nsulfur radial gradients in the Galactic discs have also been estimated.\nFinally, the enrichment in sulfur with respect to iron is nicely correlated\nwith stellar ages: older metal-poor stars have higher [S/M] ratios than younger\nmetal-rich ones. This work has confirmed that sulfur is an alfa-element that\ncould be considered to explore the Galactic populations properties." }, { "anchor": "J-PLUS: The star formation main sequence and rate density at d < 75 Mpc: Our goal is to estimate the star formation main sequence (SFMS) and the star\nformation rate density (SFRD) at z <= 0.017 (d < 75 Mpc) using the Javalambre\nPhotometric Local Universe Survey (J-PLUS) first data release, that probes\n897.4 deg2 with twelve optical bands. We extract the Halpha emission flux of\n805 local galaxies from the J-PLUS filter J0660, being the continuum level\nestimated with the other eleven J-PLUS bands, and the dust attenuation and\nnitrogen contamination corrected with empirical relations. Stellar masses (M),\nHalpha luminosities (L), and star formation rates (SFRs) were estimated by\naccounting for parameters covariances. Our sample comprises 689 blue galaxies\nand 67 red galaxies, classified in the (u-g) vs (g-z) color-color diagram, plus\n49 AGN. The SFMS is explored at log M > 8 and it is clearly defined by the blue\ngalaxies, with the red galaxies located below them. The SFMS is described as\nlog SFR = 0.83 log M - 8.44. We find a good agreement with previous estimations\nof the SFMS, especially those based on integral field spectroscopy. The Halpha\nluminosity function of the AGN-free sample is well described by a Schechter\nfunction with log L* = 41.34, log phi* = -2.43, and alpha = -1.25. Our\nmeasurements provide a lower characteristic luminosity than several previous\nstudies in the literature. The derived star formation rate density at d < 75\nMpc is log rho_SFR = -2.10 +- 0.11, with red galaxies accounting for 15% of the\nSFRD. Our value is lower than previous estimations at similar redshift, and\nprovides a local reference for evolutionary studies regarding the star\nformation history of the Universe.", "positive": "The ionization fraction gradient across the Horsehead edge: An archetype\n for molecular clouds: The ionization fraction plays a key role in the chemistry and dynamics of\nmolecular clouds. We study the H13CO+, DCO+ and HOC+ line emission towards the\nHorsehead, from the shielded core to the UV irradiated cloud edge, i.e., the\nPhotodissociation Region (PDR), as a template to investigate the ionization\nfraction gradient in molecular clouds. We analyze a PdBI map of the H13CO+\nJ=1-0 line, complemented with IRAM-30m H13CO+ and DCO+ higher-J line maps and\nnew HOC+ and CO+ observations. We compare self-consistently the observed\nspatial distribution and line intensities with detailed depth-dependent\npredictions of a PDR model coupled with a nonlocal radiative transfer\ncalculation. The chemical network includes deuterated species, 13C\nfractionation reactions and HCO+/HOC+ isomerization reactions. The role of\nneutral and charged PAHs in the cloud chemistry and ionization balance is\ninvestigated. The detection of HOC+ reactive ion towards the Horsehead PDR\nproves the high ionization fraction of the outer UV irradiated regions, where\nwe derive a low [HCO+]/[HOC+]~75-200 abundance ratio. In the absence of PAHs,\nwe reproduce the observations with gas-phase metal abundances, [Fe+Mg+...],\nlower than 4x10(-9) (with respect to H) and a cosmic-rays ionization rate of\nzeta=(5+/-3)x10(-17) s(-1). The inclusion of PAHs modifies the ionization\nfraction gradient and increases the required metal abundance. The ionization\nfraction in the Horsehead edge follows a steep gradient, with a scale length of\n~0.05 pc (or ~25''), from [e-]~10(-4) (or n_e ~ 1-5 cm(-3)) in the PDR to a few\ntimes ~10(-9) in the core. PAH^- anions play a role in the charge balance of\nthe cold and neutral gas if substantial amounts of free PAHs are present ([PAH]\n>10(-8))." }, { "anchor": "Differential Interferometric Signatures of Close Binaries of\n Supermassive Black Holes in Active Galactic Nuclei: II. Merged Broad Line\n Regions: Pairs of supermassive black holes (SMBHs) at different stages are natural\nresults of galaxy mergers in the hierarchical framework of galaxy formation and\nevolution. However, identifications of close binaries of SMBHs (CB-SMBHs) with\nsub-parsec separations in observations are still elusive. Recently,\nunprecedented spatial resolutions achieved by GRAVITY/GRAVITY+ onboard The Very\nLarge Telescope Interferometer through spectroastrometry (SA) provide new\nopportunities to resolve CB-SMBHs. Differential phase curves of CB-SMBHs with\ntwo independent broad-line regions (BLRs) are found to have distinguished\ncharacteristic structures from a single BLR \\citep{songsheng2019}. Once the\nCB-SMBH evolves to the stage where BLRs merge to form a circumbinary BLR, it\nwill hopefully be resolved by the pulsar timing array (PTA) in the near future\nas sources of nano-hertz gravitational waves. In this work, we use a\nparameterized model for circumbinary BLRs to calculate line profiles and\ndifferential phase curves for SA observations. We show that both profiles and\nphase curves exhibit asymmetries caused by the Doppler boosting effect of\naccretion disks around individual black holes, depending on the orbital\nparameters of the binary and geometries of the BLR. We also generate mock SA\ndata using the model and then recover orbital parameters by fitting the mock\ndata. Degeneracies between parameters contribute greatly to uncertainties of\nparameters but can be eased through joint analysis of multiple-epoch SA\nobservations and reverberation mappings.", "positive": "H$_2$O Masers and Protoplanetary Disk Dynamics in IC 1396 N: We report H$_2$O maser line observations of the bright-rimmed globule IC 1396\nN using a ground-space interferometer with the 10-m RadioAstron radio telescope\nas the space-based element. The source was not detected on projected baselines\n>2.3 Earth diameters, which indicates a lower limit on the maser size of L\n>0.03 AU and an upper limit on the brightness temperature of 6.25 x 10$^{12}$\nK. Positions and flux densities of maser spots were determined by fringe rate\nmapping. Multiple low-velocity features from -4.5 km/s to +0.7 km/s are seen,\nand two high-velocity features of V$_{LSR}$=-9.4 km/s and +4.4 km/s are found\nat projected distances of 157 AU and 70 AU, respectively, from the strongest\nlow-velocity feature at V$_{LSR}$=$\\sim$0.3 km/s. Maser components from the\ncentral part of the spectrum fall into four velocity groups but into three\nspatial groups. Three spatial groups of low-velocity features detected in the\n2014 observations are arranged in a linear structure about 200 AU in length.\nTwo of these groups were not detected in 1996 and possibly are jets which\nformed between 1996 and 2014. The putative jet seems to have changed direction\nin 18 years, which we explain by the precession of the jet under the influence\nof the gravity of material surrounding the globule. The jet collimation can be\nprovided by a circumstellar protoplanetary disk. There is a straight line\norientation in the V$_{LSR}$-Right Ascension diagram between the jet and the\nmaser group at V$_{LSR}$=$\\sim$0.3 km/s. However, the central group with the\nsame position but at the velocity V$_{LSR}$$\\sim$-3.4 km/s falls on a straight\nline between two high-velocity components detected in 2014. Comparison of the\nlow-velocity positions from 2014 and 1996, based on the same diagram, shows\nthat the majority of the masers maintain their positions near the central\nvelocity V$_{LSR}$=$\\sim$0.3 km/s during the 18 year period." }, { "anchor": "Connecting the X-ray properties of weak-line and typical quasars:\n testing for a geometrically thick accretion disk: We present X-ray and multiwavelength analyses of 32 weak emission-line\nquasars (WLQs) selected in a consistent and unbiased manner. New $Chandra$\n3.1-4.8 ks observations were obtained for 14 of these WLQs with C IV rest-frame\nequivalent widths (REWs) of 5-15 \\r{A}, and these serve as an X-ray\nobservational \"bridge\" between previously studied WLQs with C IV REW $\\lesssim$\n5 \\r{A} and more-typical quasars with C IV REW $\\approx$ 15-100 \\r{A}. We have\nidentified and quantified a strong dependence of the fraction of X-ray weak\nquasars upon C IV REW; this fraction declines by a factor of $\\approx 13$ (from\n$\\approx 44$% to $\\approx 3$%) for C IV REW ranging from 4-50 \\r{A}, and the\nrate of decline appears particularly strong in the 10-20 \\r{A} range. The\ndependence broadly supports the proposed \"shielding\" model for WLQs, in which a\ngeometrically and optically thick inner accretion disk, expected for a quasar\naccreting at a high Eddington ratio, both prevents ionizing EUV/X-ray photons\nfrom reaching the high-ionization broad emission-line region and also sometimes\nblocks the line-of-sight to the central X-ray emitting region. This model is\nalso supported by the hard average spectral shape of X-ray weak WLQs (with a\npower-law effective photon index of $\\Gamma_{\\rm eff}=1.19^{+0.56}_{-0.45}$).\nAdditionally, we have examined UV continuum/emission-line properties that might\ntrace X-ray weakness among WLQs, confirming that red UV continuum color is the\nmost-effective tracer.", "positive": "Expanding shells around young clusters -- S 171/Be 59: Some HII regions that surround young stellar clusters are bordered by\nmolecular shells that appear to expand at a rate inconsistent with our current\nmodel simulations. In this study we focus on the dynamics of Sharpless 171\n(including NGC 7822), which surrounds the cluster Berkeley 59. We aim to\ncompare the velocity pattern over the molecular shell with the mean radial\nvelocity of the cluster for estimates of the expansion velocities of different\nshell structures, and to match the observed properties with model simulations.\nOptical spectra of 27 stars located in Berkeley 59 were collected at the Nordic\nOptical Telescope, and a number of molecular structures scattered over the\nentire region were mapped in $^{13}$CO(1-0) at Onsala Space Observatory. We\nobtained radial velocities and MK classes for the cluster's stars. At least\nfour of the O stars are found to be spectroscopic binaries, in addition to one\ntriplet system. From these data we obtain the mean radial velocity of the\ncluster. From the $^{13}$CO spectra we identify three shell structures,\nexpanding relative to the cluster at moderate velocity (4 km/s), high velocity\n(12 km/s), and in between. The high-velocity cloudlets extend over a larger\nradius and are less massive than the low-velocity cloudlets. We performed a\nmodel simulation to understand the evolution of this complex. Our simulation of\nthe Sharpless 171 complex and Berkeley 59 cluster demonstrates that the\nindividual components can be explained as a shell driven by stellar winds from\nthe massive cluster members. However, our relatively simple model produces a\nsingle component. Modelling of the propagation of shell fragments through a\nuniform interstellar medium demonstrates that dense cloudlets detached from the\nshell are decelerated less efficiently than the shell itself. They can reach\ngreater distances and retain higher velocities than the shell." }, { "anchor": "Some Die Filthy Rich: The Diverse Molecular Gas Contents of\n Post-starburst Galaxies Probed by Dust Absorption: Quenched post-starburst galaxies (QPSBs) are a rare but important class of\ngalaxies that show signs of rapid cessation or recent rejuvenation of star\nformation. A recent observation shows that about half of QPSBs have large\namounts of cold gas. This molecular CO sample is, however, too small and is not\nwithout limitations. Our work aims to verify previous results by applying a new\nmethod to study a uniformly selected sample, more than 10 times larger. In\nparticular, we present detailed analysis of H$\\alpha$/H$\\beta$ ratios of\nface-on QPSBs at $z = 0.02 - 0.15$ and with $M_\\star =\n10^{10}-10^{11}\\,M_\\odot$. We interpret the H$\\alpha$/H$\\beta$ ratios by\napplying our recent gas mass calibration, which is based on non-PSB galaxies\nbut predicts gas masses that are consistent with CO observations of $\\sim 100$\nPSBs. We estimate the molecular gas by either using PSBs with well-measured\nH$\\alpha$/H$\\beta$ ratios or by measuring them from stacked spectra. Our\nanalysis reveals that QPSBs have a wide range of H$\\alpha$/H$\\beta$ ratios and\nmolecular gas fractions that overlap with the typical gas fractions of\nstar-forming or quiescent galaxies: H$\\alpha$/H$\\beta \\approx 3-8$ and\n$f_\\mathrm{H_2} \\approx 1\\%-20\\%$ with median $f_\\mathrm{H_2} \\approx 4\\%-6\\%$,\nwhich correspond to $M_\\mathrm{H_2} \\approx (1-3) \\times 10^{9} \\,M_\\odot$. Our\nresults indicate that large reservoirs of cold gas are still present in\nsignificant numbers of QPSBs, and that they arguably were not removed or\ndestroyed by feedback from active galactic nuclei.", "positive": "Clues to growth and disruption of two neighbouring spiral arms of the\n Milky Way: Studying the nature of spiral arms is essential for understanding the\nformation of the intricate disc structure of the Milky Way. The European Space\nAgency's Gaia mission has provided revolutionary observational data that have\nuncovered detailed kinematical features of stars in the Milky Way. However, so\nfar the nature of spiral arms continues to remain a mystery. Here we present\nthat the stellar kinematics traced by the classical Cepheids around the Perseus\nand Outer spiral arms in the Milky Way shows strikingly different kinematical\nproperties from each other: the radial and azimuthal velocities of Cepheids\nwith respect to the Galactic centre show positive and negative correlations in\nthe Perseus and Outer arms, respectively. We also found that the dynamic spiral\narms commonly seen in an N-body/hydrodynamics simulation of a Milky Way-like\ngalaxy can naturally explain the observed kinematic trends. Furthermore, a\ncomparison with such a simulation suggests that the Perseus arm is being\ndisrupted while the Outer arm is growing. Our findings suggest that two\nneighbouring spiral arms in distinct evolutionary phases - growing and\ndisrupting phases - coexist in the Milky Way." }, { "anchor": "On the influence of rings on orbital velocities: We analyze the possible effect of rings on orbital velocities in galaxies.\nThe superposition of the central force with the gravitational forces induced by\nthe rings opens up various possibilities of the course of orbital velocities.\nThe orbital velocity depends on the position of the star in the ring. We\nillustrate this dependence on several models, where we show the course of\npotential curves and the curves of field strength.", "positive": "Reconstructing the velocity dispersion profiles from the line-of-sight\n kinematic data in disc galaxies: We present a modification of the method for reconstructing the stellar\nvelocity ellipsoid (SVE) in disc galaxies. Our version does not need any\nparametrization of the velocity dispersion profiles and uses only one\nassumption that the ratio $\\sigma_z/\\sigma_R$ remains constant along the\nprofile or along several pieces of the profile. The method was tested on two\ngalaxies from the sample of other authors and for the first time was applied to\nthree lenticular galaxies NGC~1167, NGC~3245 and NGC~4150 as well as to one Sab\ngalaxy NGC~338. We found that for galaxies with a high inclination ($i\n>55-60^\\circ$) it is difficult or rather impossible to extract the information\nabout SVE while for galaxies at an intermediate inclination the procedure of\nextracting is successful. For NGC~1167 we managed to reconstruct SVE, provided\nthat the value of $\\sigma_z/\\sigma_R$ is piecewise constant. We found\n$\\sigma_z/\\sigma_R=0.7$ for the inner parts of the disc and\n$\\sigma_z/\\sigma_R=0.3$ for the outskirts. We also obtained a rigid constrain\non the value of the radial velocity dispersion $\\sigma_R$ for highly inclined\ngalaxies and tested the result using the asymmetric drift equation, provided\nthat the gas rotation curve is available." }, { "anchor": "Distances to nearby molecular clouds traced by young stars: I present a catalog of distances to 63 molecular clouds located within ~2.5\nkpc of the Sun. The cloud distances are derived based on utilizing the Gaia DR3\nparallaxes of the young stellar objects (YSOs). By identifying AllWISE YSO\ncandidates (YSOCs) with infrared excesses and combining them with published\nYSOC catalogs, I compile an all-sky YSOC sample that is devoid of a significant\nproportion of contaminants. Using Gaia DR3 astrometric measurements, I\nassociate over 3000 YSOCs with 63 local clouds and obtain the average distance\nto each cloud by fitting the YSOC parallax distribution within the cloud. I\nfind good agreements with typical scatter of <10% between my new cloud\ndistances and previous distance estimates. Unlike cloud distances obtained\nusing stellar extinction, my catalog provides distances to the relatively dense\nareas of local clouds, which makes them more appropriate references for\ninvestigating the physical properties of nearby dense regions.", "positive": "Galaxy evolution in modified gravity simulations: using passive galaxies\n to constrain gravity with upcoming surveys: We present a quantitative analysis of the properties of galaxies and\nstructures evolving in universes dominated by different modified gravitational\nmodels, including two variants of the f(R)-gravity (F) and two of the\nDvali-Gabdadze-Poratti (N) braneworld model, which respectively feature the\nchameleon and Vainshtein screening mechanisms. Using the Simulation\nHYdrodynamics BeyONd Einstein (SHYBONE) cosmological hydrodynamical\nfull-physics simulations suite, we study the departures in the properties of\ngalaxies residing in different environments with respect to the standard model\n(GR). Using two different criteria to compare, we find that structures formed\nwithin modified gravity tend to show a denser gas density profile than their GR\ncounterparts. Within the different modified gravity models, N1 and F5 gravity\nmodels show greater departures from the standard model, with gas density\nprofiles $\\rho_{\\rm IGM} \\geq 30\\%$ denser in the outskirts for the N1 model,\nand in the inner parts for the F5 model. Additionally, we find that haloes\nevolving in MG universes show, in general, larger quenched fractions than GR,\nreaching up to $20\\%$ larger quenching fractions in F5 regardless of the\nstellar mass of the galaxy. With respect to the other models, F6, N1 and N5\nshow slightly larger quenched fractions, but no strong differences can be\nfound. These results directly impact the colour distribution of galaxies,\nmaking them in MG models redder and older than their GR counterparts. Like GR,\nonce the environment starts to play a role, galaxies rapidly get quenched and\nthe differences between models vanish." }, { "anchor": "Dissecting the central regions of OH 231.8 + 4.2 with ALMA: a salty\n rotating disk at the base of a young bipolar outflow: We present ALMA continuum and molecular line emission maps at $\\sim$1 mm of\nOH 231.8, a well studied bipolar nebula around an AGB star. The excellent\nangular resolution of our maps ($\\sim$20 mas) allows us to scrutinise the\ncentral nebular regions of OH 231.8, which hold the clues to unravel how this\niconic object assembled its complex nebular architecture. We report, for the\nfirst time in this object and others of its kind, the discovery of a rotating\ncircumbinary disk selectively traced by NaCl, KCl, and H$_2$O emission lines.\nThis represents the first detection of KCl in an oxygen-rich AGB circumstellar\nenvelope. The rotating disk, of radius $\\sim$30 au, lies at the base of a young\nbipolar wind traced by SiO and SiS emission, which also presents signs of\nrotation at its base. The NaCl equatorial structure is characterised by a mean\nrotation velocity of $\\sim$4 km s$^{-1}$ and extremely low expansion speeds,\n$\\sim$3 km s$^{-1}$. The outflow has a predominantly expansive kinematics\ncharacterised by a constant radial velocity gradient of $\\sim$65 km s$^{-1}$\narcsec$^{-1}$ at its base. Beyond $r$$\\sim$350 au, the gas in the outflow\ncontinues radially flowing at a constant terminal speed of $\\sim$16 km\ns$^{-1}$. Our continuum maps reveal a spatially resolved dust disk-like\nstructure perpendicular to the outflow, with the NaCl, KCl and H$_2$O emission\narising from the disk's surface layers. Within the disk, we also identify an\nunresolved point continuum source, which likely represents the central\nMira-type star QX Pup enshrouded by a $\\sim$3 $R_{\\star}$ component of hot\n($\\sim$1400 K) freshly formed dust. The point source is slightly off-centered\nfrom the disk centroid, enabling us for the first time to place constraints to\nthe orbital separation and period of the central binary system, $a$$\\sim$20 au\nand $P_{\\rm orb}$$\\sim$55 yr, respectively. (abridged).", "positive": "Radio galaxies in ZFOURGE/NMBS: no difference in the properties of\n massive galaxies with and without radio-AGN out to z = 2.25: In order to reproduce the high-mass end of the galaxy mass-distribution, some\nprocess must be responsible for the suppression of star-formation in the most\nmassive of galaxies. Commonly Active Galactic Nuclei (AGN) are invoked to\nfulfil this role, but the exact means by which they do so is still the topic of\nmuch debate, with studies finding evidence for both the suppression and\nenhancement of star-formation in AGN hosts. Using the ZFOURGE and NMBS galaxy\nsurveys, we investigate the host galaxy properties of a mass-limited\n(M$_{\\odot}$ $\\ge$ 10$^{10.5}$ M$_{\\odot}$), high-luminosity (L$_{1.4}$ $>$\n10$^{24}$ W Hz$^{-1}$) sample of radio-loud Active Galactic Nuclei to a\nredshift of z = 2.25. In contrast to low redshift studies, which associate\nradio-AGN activity with quiescent hosts, we find that the majority of z $>$ 1.5\nradio-AGN are hosted by star-forming galaxies. Indeed, the stellar populations\nof radio-AGN are found to evolve with redshift in a manner that is consistent\nwith the non-AGN mass-similar galaxy population. Interestingly, we find the\nradio-AGN fraction is constant across a redshift range of 0.25 $\\le$ z $<$\n2.25, perhaps indicating that the radio-AGN duty cycle has little dependence on\nredshift or galaxy type. We do however see a strong relation between the\nradio-AGN fraction and stellar mass, with radio-AGN becoming rare below $\\sim$\n10$^{10.5}$ M$_{\\odot}$ or a halo-mass of 10$^{12}$ M$_{\\odot}$. This halo-mass\nthreshold is in good agreement with simulations that initiate radio-AGN\nfeedback at this mass limit. Despite this we find that radio-AGN host\nstar-formation rates are consistent with the non-AGN mass-similar galaxy\nsample, suggesting that while radio-AGN are in the right place to suppress\nstar-formation in massive galaxies they are not necessarily responsible for\ndoing so." }, { "anchor": "Physical Conditions and Kinematics of the Filamentary Structure in Orion\n Molecular Cloud 1: We have studied the structure and kinematics of the dense molecular gas in\nthe Orion Molecular Cloud 1 (OMC1) region with the N2H+ 3-2 line. The 6'x9'\n(~0.7x1.1 pc) region surrounding the Orion KL core has been mapped with the\nSubmillimeter Array (SMA) and the Submillimeter Telescope (SMT). The combined\nSMA and SMT image having a resolution of ~5.4\" (~2300 au) reveals multiple\nfilaments with a typical width of 0.02-0.03 pc. On the basis of the non-LTE\nanalysis using the N2H+ 3-2 and 1-0 data, the density and temperature of the\nfilaments are estimated to be ~10^7 cm-3 and ~15-20 K, respectively. The core\nfragmentation is observed in three massive filaments, one of which shows the\noscillations in the velocity and intensity that could be the signature of\ncore-forming gas motions. The gas kinetic temperature is significantly enhanced\nin the eastern part of OMC1, likely due to the external heating from the high\nmass stars in M42 and M43. In addition, the filaments are colder than their\nsurrounding regions, suggesting the shielding from the external heating due to\nthe dense gas in the filaments. The OMC1 region consists of three sub-regions,\ni.e. north, west, and south of Orion KL, having different radial velocities\nwith sharp velocity transitions. There is a north-to-south velocity gradient\nfrom the western to the southern regions. The observed velocity pattern\nsuggests that dense gas in OMC1 is collapsing globally toward the high-mass\nstar-forming region, Orion Nebula Cluster.", "positive": "Radio continuum surveys and galaxy evolution: The AGN view: Understanding how galaxies form in the early universe and their subsequent\nevolution through cosmic time is a major goal of modern astrophysics.\nPanchromatic look-back sky surveys significantly advanced the field in the past\ndecades, and we are now entering an even more fruitful period - a 'golden age'\nof radio astronomy - with upgraded, and new facilities delivering an order of\nmagnitude increase in sensitivity. An overview of recent developments in radio\ncontinuum sky surveys, focusing on the physical properties and cosmic evolution\nof radio AGN since z~5 is presented here." }, { "anchor": "HI observations of three compact high-velocity clouds around the Milky\n Way: We present deep HI observations of three compact high-velocity clouds\n(CHVCs). The main goal is to study their diffuse warm gas and compact cold\ncores. We use both low- and high-resolution data obtained with the 100 m\nEffelsberg telescope and the Westerbork Synthesis Radio Telescope (WSRT). The\ncombination is essential in order to study the morphological properties of the\nclouds since the single-dish telescope lacks a sufficient angular resolution\nwhile the interferometer misses a large portion of the diffuse gas. Here\nsingle-dish and interferometer data are combined in the image domain with a new\ncombination pipeline. The combination makes it possible to examine interactions\nbetween the clouds and their surrounding environment in great detail. The\napparent difference between single-dish and radio interferometer total flux\ndensities shows that the CHVCs contain a considerable amount of diffuse gas\nwith low brightness temperatures. A Gaussian decomposition indicates that the\nclouds consist predominantly of warm gas.", "positive": "Anisotropic satellite galaxy quenching modulated by supermassive black\n hole activity: The evolution of satellite galaxies is shaped by their constant interaction\nwith the circum galactic medium surrounding central galaxies, which in turn may\nbe affected by gas and energy ejected from the central supermassive black hole.\nHowever, the nature of this coupling between black holes and galaxies is highly\ndebated and observational evidence remains scarce. Here we report an analysis\nof archival data on 124,163 satellite galaxies in the potential wells of 29,631\ndark matter halos with masses between 10$^{12}$ and $10^{14}$ solar masses. We\nfind that quiescent satellites are relatively less frequent along the minor\naxis of their central galaxies. This observation might appear counterintuitive\nas black hole activity is expected to eject mass and energy preferentially in\nthe direction of the minor axis of the host galaxy. However, we show that the\nobserved signal results precisely from the ejective nature of black hole\nfeedback in massive halos, as active galactic nuclei-powered outflows clear out\nthe circumgalactic medium, reducing the ram pressure and thus preserving star\nformation. This interpretation is supported by the IllustrisTNG suite of\ncosmological numerical simulations, where a similar modulation is observed even\nthough the sub-grid implementation of black hole feedback is effectively\nisotropic. Our results provide compelling observational evidence for the role\nof black holes in regulating galaxy evolution over spatial scales differing by\nseveral orders of magnitude." }, { "anchor": "Bimodality of low-redshift circumgalactic O VI in non-equilibrium EAGLE\n zoom simulations: We introduce a series of 20 cosmological hydrodynamical simulations of Lstar\n(M_200 =10^11.7 - 10^12.3 Msol) and group-sized (M_200 = 10^12.7 - 10^13.3\nMsol) haloes run with the model used for the EAGLE project, which additionally\nincludes a non-equilibrium ionization and cooling module that follows 136 ions.\nThe simulations reproduce the observed correlation, revealed by COS-Halos at\nz~0.2, between O VI column density at impact parameters b < 150 kpc and the\nspecific star formation rate (sSFR=SFR/Mstar) of the central galaxy at z~0.2.\nWe find that the column density of circumgalactic O VI is maximal in the haloes\nassociated with Lstar galaxies, because their virial temperatures are close to\nthe temperature at which the ionization fraction of O VI peaks (T~10^5.5 K).\nThe higher virial temperature of group haloes (> 10^6 K) promotes oxygen to\nhigher ionization states, suppressing the O VI column density. The observed NO\nVI-sSFR correlation therefore does not imply a causal link, but reflects the\nchanging characteristic ionization state of oxygen as halo mass is increased.\nIn spite of the mass-dependence of the oxygen ionization state, the most\nabundant circumgalactic oxygen ion in both Lstar and group haloes is O VII; O\nVI accounts for only 0.1% of the oxygen in group haloes and 0.9-1.3% with Lstar\nhaloes. Nonetheless, the metals traced by O VI absorbers represent a fossil\nrecord of the feedback history of galaxies over a Hubble time; their\ncharacteristic epoch of ejection corresponds to z > 1 and much of the ejected\nmetal mass resides beyond the virial radius of galaxies. For both Lstar and\ngroup galaxies, more of the oxygen produced and released by stars resides in\nthe circumgalactic medium (within twice the virial radius) than in the stars\nand ISM of the galaxy.", "positive": "The evolution of the galaxy content of dark matter haloes: We use the halo occupation distribution (HOD) framework to characterise the\npredictions from two independent galaxy formation models for the galactic\ncontent of dark matter haloes and its evolution with redshift. Our galaxy\nsamples correspond to a range of fixed number densities defined by stellar mass\nand span $0 \\le z \\le 3$. We find remarkable similarities between the model\npredictions. Differences arise at low galaxy number densities which are\nsensitive to the treatment of heating of the hot halo by active galactic\nnuclei. The evolution of the form of the HOD can be described in a relatively\nsimple way, and we model each HOD parameter using its value at $z=0$ and an\nadditional evolutionary parameter. In particular, we find that the ratio\nbetween the characteristic halo masses for hosting central and satellite\ngalaxies can serve as a sensitive diagnostic for galaxy evolution models. Our\nresults can be used to test and develop empirical studies of galaxy evolution\nand can facilitate the construction of mock galaxy catalogues for future\nsurveys." }, { "anchor": "The MOSDEF Survey: Differences in SFR and Metallicity for\n Morphologically-Selected Mergers at z~2: We study the properties of 55 morphologically-identified merging galaxy\nsystems at z~2. These systems are flagged as mergers based on features such as\ntidal tails, double nuclei, and asymmetry. Our sample is drawn from the MOSFIRE\nDeep Evolution Field (MOSDEF) survey, along with a control sample of isolated\ngalaxies at the same redshift. We consider the relationships between stellar\nmass, star formation rate (SFR), and gas-phase metallicity for both merging and\nnon-merging systems. In the local universe, merging systems are characterized\nby an elevated SFR and depressed metallicity compared to isolated systems at a\ngiven mass. Our results indicate SFR enhancement and metallicity deficit for\nmerging systems relative to non-merging systems for a fixed stellar mass at\nz~2, though larger samples are required to establish these preliminary results\nwith higher statistical significance. In future work, it will be important to\nestablish if the enhanced SFR and depressed metallicity in high-redshift\nmergers deviate from the \"fundamental metallicity relation,\" as is observed in\nmergers in the local universe, and therefore shed light on gas flows during\ngalaxy interactions.", "positive": "SIGGMA: A Survey of Ionized Gas in the Galaxy, Made with the Arecibo\n Telescope: A Survey of Ionized Gas in the Galaxy, made with the Arecibo telescope\n(SIGGMA) uses the Arecibo L-band Feed Array (ALFA) to fully sample the Galactic\nplane (30 < l < 75 and -2 < b < 2; 175 < l < 207 and -2 < b < 1) observable\nwith the telescope in radio recombination lines (RRLs). Processed data sets are\nbeing produced in the form of data cubes of 2 degree (along l) x 4 degree\n(along b) x 151 (number of channels), archived and made public. The 151\nchannels cover a velocity range of 600 km/s and the velocity resolution of the\nsurvey changes from 4.2 km/s to 5.1 km/s from the lowest frequency channel to\nthe highest frequency channel, respectively.RRL maps with 3.4 arcmin resolution\nand line flux density sensitivity of 0.5 mJy will enable us to identify new HII\nregions, measure their electron temperatures, study the physics of\nphotodissociation regions (PDRs) with carbon RRLs, and investigate the origin\nof the extended low density medium (ELDM). Twelve Hn{\\alpha} lines fall within\nthe 300 MHz bandpass of ALFA; they are resampled to a common velocity\nresolution to improve the signal-to-noise ratio (SN) by a factor of 3 or more\nand preserve the line width. SIGGMA will produce the most sensitive fully\nsampled RRL survey to date. Here we discuss the observing and data reduction\ntechniques in detail. A test observation toward the HII region complex\nS255/S257 has detected Hn{\\alpha} and Cn{\\alpha} lines with SN>10." }, { "anchor": "Spectral analysis of spatially-resolved 3C295 (sub-arcsecond resolution)\n with the International LOFAR Telescope: 3C295 is a bright, compact steep spectrum source with a well-studied\nintegrated radio spectral energy distribution (SED) from 132 MHz to 15 GHz.\nHowever, spatially resolved spectral studies have been limited due to a lack of\nhigh resolution images at low radio frequencies. These frequencies are crucial\nfor measuring absorption processes, and anchoring the overall spectral\nmodelling of the radio SED. In this paper, we use International LOFAR\n(LOw-Frequency ARray) Telescope (ILT) observations of 3C295 to study its\nspatially resolved spectral properties with sub-arcsecond resolution at 132\nMHz. Combining our new 132 MHz observation with archival data at 1.6 GHz, 4.8\nGHz, and 15 GHz, we are able to carry out a resolved radio spectral analysis.\nThe spectral properties of the hotspots provides evidence for low frequency\nflattening. In contrast, the spectral shape across the lobes is consistent with\na JP spectral ageing model. Using the integrated spectral information for each\ncomponent, we then fit low-frequency absorption models to the hotspots, finding\nthat both free-free absorption and synchrotron self-absorption models provide a\nbetter fit to the data than a standard power law. Although we can say there is\nlow-frequency absorption present in the hotspots of 3C295, future observations\nwith the Low Band Antenna of the ILT at 55 MHz may allow us to distinguish the\ntype of absorption.", "positive": "New molecules in IRC+10216: confirmation of C$_5$S and tentative\n identification of MgCCH, NCCP, and SiH$_3$CN: The C-star envelope IRC+10216 harbors a rich variety of molecules, with more\nthan 80 detected to date. During the course of a $\\lambda$ 3 mm survey of\nIRC+10216 carried out with the IRAM 30-m telescope we have detected various\nweak lines, with antenna temperatures of a few mK, that we assign to rotational\ntransitions of four new molecules. The observation of three lines of C$_5$S\nconfirms a previous tentative identification of this molecule by Bell et al.\n(1993) based on a line at 24.0 GHz. We also report the tentative identification\nof three molecules not yet observed in space: MgCCH, the first metal acetylide\ndetected in space, and NCCP and SiH$_3$CN, the phosphorus and silicon analogs\nof cyanogen (NCCN) and methyl cyanide (CH$_3$CN). We derive the following\ncolumn densities: $N$(C$_5$S) = (2-14) $\\times$ 10$^{12}$ cm$^{-2}$ (depending\non the rotational temperature adopted), $N$(MgCCH) = 2 $\\times$ 10$^{12}$\ncm$^{-2}$, $N$(NCCP) = 7 $\\times$ 10$^{11}$ cm$^{-2}$, and $N$(SiH$_3$CN) =\n10$^{12}$ cm$^{-2}$. The S-bearing carbon chain C$_5$S is less abundant than\nC$_3$S, while MgCCH has an abundance in between that of MgNC and those of MgCN\nand HMgNC. On the other hand, NCCP and SiH$_3$CN are the least abundant P- and\nSi-bearing molecules observed to date in IRC+10216. Based on the behavior of\nsimilar molecules it is likely that these four species are formed in the outer\ncircumstellar layers of IRC+10216. We discuss possible gas-phase formation\nroutes." }, { "anchor": "A SCUBA-2 850$\u03bc$m Survey of Heavily Reddened Quasars at z~2: We present new 850$\\mu$m SCUBA-2 observations for a sample of 19 heavily\nreddened Type-I quasars at redshifts $z\\sim$2 with dust extinctions of\nA$_{\\rm{V}} \\simeq 2-6$ mag. Three of the 19 quasars are detected at\n$>$3$\\sigma$ significance corresponding to an 850$\\mu$m flux-limit of\n$\\gtrsim$4.8 mJy. Assuming the 850$\\mu$m flux is dominated by dust heating due\nto star formation, very high star formation rates (SFR) of $\\sim$2500-4500\nM$_\\odot$ yr$^{-1}$ in the quasar host galaxies are inferred. Even when\nconsidering a large contribution to the 850$\\mu$m flux from dust heated by the\nquasar itself, significant SFRs of $\\sim$600-1500 M$_\\odot$ yr$^{-1}$ are\nnevertheless inferred for two of the three detected quasars. We stack the\nremaining 16 heavily reddened quasars and derive an average 3$\\sigma$ upper\nlimit on the SFRs in these quasar host galaxies of $<$880 M$_\\odot$ yr$^{-1}$.\nThe number counts of sub-mm galaxies in the total survey area (134.3arcmin$^2$)\nare consistent with predictions from blank-field surveys. There are, however,\nindividual quasars where we find evidence for an excess of associated sub-mm\ngalaxies. For two quasars, higher spatial resolution and spectroscopic ALMA\nobservations confirm the presence of an excess of sub-mm sources. We compare\nthe 850$\\mu$m detection rate of our quasars to both unobscured, ultraviolet\nluminous quasars as well as the much more obscured population of mid-infrared\nluminous Hot Dust Obscured Galaxies (HotDOGs). When matched by luminosity and\nredshift, we find no significant differences in the 850$\\mu$m flux densities of\nthese various quasar populations given the current small sample sizes.", "positive": "Determination of the Spiral Pattern Speed in the Galaxy from Three\n Samples of Stars: We invoke the estimates of the amplitudes of the velocity perturbations $f_R$\nand $f_\\theta$ caused by the influence of a spiral density wave that have been\nobtained by us previously from three stellar samples. These include Galactic\nmasers with measured VLBI trigonometric parallaxes and proper motions, OB2\nstars, and Cepheids. From these data we have obtained new estimates of the\nspiral pattern speed in the Galaxy $\\Omega_p:$ $24.61\\pm2.06$, $24.71\\pm1.29$\nand $25.98\\pm1.37$~km s$^{-1}$ kpc$^{-1}$ from the samples of masers, OB2\nstars, and Cepheids, respectively. The corotation radii for these three samples\n$R_{\\rm cor}/R_0$ are $1.16\\pm0.09$, $1.15\\pm0.06$ and $1.09\\pm0.06,$\nsuggesting that the corotation circle is located between the Sun and the\nPerseus arm segment." }, { "anchor": "Constant light element abundances suggest that the extended P1 in NGC\n 2808 is not a consequence of CNO-cycle nucleosynthesis: Recent photometric results have identified a new population among globular\ncluster stars. This population, referred to as the ``extended P1'', has been\nsuggested to be the manifestation of a new abundance pattern where the initial\nmass fraction of He changes among cluster stars that share the same CNO values.\nThe current paradigm for the formation of the multiple stellar populations in\nglobular clusters assumes that variations in He are the product of chemical\n``enrichment'' by the ashes of the CNO-cycle (which changes He and other\nelements like C, N and O simultaneously). We obtained MIKE@Magellan spectra of\nsix giant stars in NGC 2808, a cluster with one of the strongest examples of\nthe extended P1 population. We provide the first complete characterization of\nthe light elements abundances for the stars along a significant range of the\nextended P1 photometric group. The stars from our sample appear to be\nhomogeneous in C, N, O, Na, Mg and Al. The lack of a significant change in\nthese products of the CNO-cycle, suggest that unlike the rest of the\npopulations identified to date, the photometric changes responsible for the\nextended P1 feature are a consequence of an alternative mechanism. Our\nmeasurements, are consistent with the interpretations where the changes of the\nHe mass fraction among these stars could be consequence of p-p chain\nnucleosynthesis (which could increase the He in stars without affecting heavier\nelements). Having said that, direct measurements of He are necessary to\nconclude if variations of this element are present among extended P1 stars.", "positive": "The Origin and Evolution of Fast and Slow Rotators in the Illustris\n Simulation: Using the Illustris simulation, we follow thousands of elliptical galaxies\nback in time to identify how the dichotomy between fast and slow rotating\nellipticals (FRs and SRs) develops. Comparing to the\n$\\textrm{ATLAS}^\\textrm{3D}$ survey, we show that Illustris reproduces similar\nelliptical galaxy rotation properties, quantified by the degree of ordered\nrotation, $\\lambda_\\textrm{R}$. There is a clear segregation between low-mass\n($M_{\\rm *} < 10^{11} M_{\\rm \\odot}$) ellipticals, which form a smooth\ndistribution of FRs, and high-mass galaxies ($M_{\\rm *} > 10^{11.5} M_{\\rm\n \\odot}$), which are mostly SRs, in agreement with observations. We find that\nSRs are very gas poor, metal rich and red in colour, while FRs are generally\nmore gas rich and still star forming. We suggest that ellipticals begin\nnaturally as FRs and, as they grow in mass, lose their spin and become SRs.\nWhile at $z = 1$, the progenitors of SRs and FRs are nearly indistinguishable,\ntheir merger and star formation histories differ thereafter. We find that major\nmergers tend to disrupt galaxy spin, though in rare cases can lead to a\nspin-up. No major difference is found between the effects of gas-rich and\ngas-poor mergers and the amount of minor mergers seem to have little\ncorrelation with galaxy spin. In between major mergers, lower-mass ellipticals,\nwhich are mostly gas-rich, tend to recover their spin by accreting gas and\nstars. For galaxies with $M_{\\rm *}$ above $\\sim 10^{11} M_{\\rm \\odot}$, this\ntrend reverses; galaxies only retain or steadily lose their spin. More frequent\nmergers, accompanied by an inability to regain spin, lead massive ellipticals\nto lose most of ordered rotation and transition from FRs to SRs." }, { "anchor": "Rotation Measure synthesis study and polarized properties of PSR\n J1745-2900 at 7 mm: We present results of interferometric polarization observations of the\nrecently discovered magnetar J1745-2900 in the vicinity of the Galactic center.\nThe observations were made with the Karl G. Jansky Very Large Array (VLA) on 21\nFebruary 2014 in the range 40-48 GHz. The full polarization mode and A\nconfiguration of the array were used. The average total and linearly polarized\nflux density of the pulsar amounts to 2.3$\\pm$0.31 mJy/beam and 1.5$\\pm$0.2\nmJy/beam, respectively. Analysis shows a rotation measure (RM) of\n(-67$\\pm$3)x10$^3$ rad/m$^2$, which is in a good agreement with previous\nmeasurements at longer wavelengths. These high frequency observations are\nsensitive to RM values of up to ~2x10$^7$ rad/m$^2$. However, application of\nthe Faraday RM synthesis technique did not reveal other significant RM\ncomponents in the pulsar emission. This supports an external nature of a single\nthin Faraday-rotating screen which should be located close to the Galactic\ncenter. The Faraday corrected intrinsic electric vector position angle is\n16$\\pm$9 deg East of North, and coincides with the position angle of the\npulsar's transverse velocity. All measurements of the pulsar's RM value to\ndate, including the one presented here, well agree within errors, which points\ntowards a steady nature of the Faraday-rotating medium.", "positive": "The average structural evolution of massive galaxies can be reliably\n estimated using cumulative galaxy number densities: Galaxy evolution can be studied observationally by linking progenitor and\ndescendant galaxies through an evolving cumulative number density selection.\nThis procedure can reproduce the expected evolution of the median stellar mass\nfrom abundance matching. However, models predict an increasing scatter in main\nprogenitor masses at higher redshifts, which makes galaxy selection at the\nmedian mass unrepresentative. Consequently, there is no guarantee that the\nevolution of other galaxy properties deduced from this selection are reliable.\nDespite this concern, we show that this procedure approximately reproduces the\nevolution of the average stellar density profile of main progenitors of M =\n10^11.5 Msun galaxies, when applied to the EAGLE hydrodynamical simulation. At\nz > 3.5 the aperture masses disagree by about a factor two, but this\ndiscrepancy disappears when we include the expected scatter in cumulative\nnumber densities. The evolution of the average density profile in EAGLE broadly\nagrees with observations from UltraVISTA and CANDELS, suggesting an inside-out\ngrowth history for these massive galaxies over 0 < z < 5. However, for z < 2\nthe inside-out growth trend is stronger in EAGLE. We conclude that cumulative\nnumber density matching gives reasonably accurate results when applied to the\nevolution of the mean density profile of massive galaxies." }, { "anchor": "New class I methanol masers: We review properties of all known collisionally pumped (class I) methanol\nmaser series based on observations with the Australia Telescope Compact Array\n(ATCA) and the Mopra radio telescope. Masers at 36, 84, 44 and 95 GHz are most\nwidespread, while 9.9, 25, 23.4 and 104 GHz masers are much rarer, tracing the\nmost energetic shocks. A survey of many southern masers at 36 and 44 GHz\nsuggests that these two transitions are highly complementary. The 23.4 GHz\nmaser is a new type of rare class I methanol maser, detected only in two\nhigh-mass star-forming regions, G357.97-0.16 and G343.12-0.06, and showing a\nbehaviour similar to 9.9, 25 and 104 GHz masers. Interferometric positions\nsuggest that shocks responsible for class I masers could arise from a range of\nphenomena, not merely an outflow scenario. For example, some masers might be\ncaused by interaction of an expanding HII region with its surrounding molecular\ncloud. This has implications for evolutionary sequences incorporating class I\nmethanol masers if they appear more than once during the evolution of the\nstar-forming region. We also make predictions for candidate maser transitions\nat the ALMA frequency range.", "positive": "Whistler-regulated MHD: Transport equations for electron thermal\n conduction in the high $\u03b2$ intracluster medium of galaxy clusters: Transport equations for electron thermal energy in the high $\\beta_e$\nintracluster medium (ICM) are developed that include scattering from both\nclassical collisions and self-generated whistler waves. The calculation employs\nan expansion of the kinetic electron equation along the ambient magnetic field\nin the limit of strong scattering and assumes whistler waves with low phase\nspeeds $V_w\\sim{v}_{te}/\\beta_e\\ll{v}_{te}$ dominate the turbulent spectrum,\nwith $v_{te}$ the electron thermal speed and $\\beta_e\\gg1$ the ratio of\nelectron thermal to magnetic pressure. We find: (1) temperature-gradient-driven\nwhistlers dominate classical scattering when $L_c>L/\\beta_e$, with $L_c$ the\nclassical electron mean-free-path and $L$ the electron temperature scale\nlength, and (2) in the whistler dominated regime the electron thermal flux is\ncontrolled by both advection at $V_w$ and a comparable diffusive term. The\nfindings suggest whistlers limit electron heat flux over large regions of the\nICM, including locations unstable to isobaric condensation. Consequences\ninclude: (1) the Field length decreases, extending the domain of thermal\ninstability to smaller length-scales, (2) the heat flux temperature dependence\nchanges from $T_e^{7/2}/L$ to $V_wnT_e\\sim{T}_e^{1/2}$, (3) the magneto-thermal\nand heat-flux driven buoyancy instabilities are impaired or completely\ninhibited, and (4) sound waves in the ICM propagate greater distances, as\ninferred from observations. This description of thermal transport can be used\nin macroscale ICM models." }, { "anchor": "MaNGA DynPop -- V. The dark-matter fraction versus stellar velocity\n dispersion relation and initial mass function variations: dynamical models\n and full spectrum fitting of integral-field spectroscopy: Using the final MaNGA sample (DR17) of 10K galaxies, we investigate the dark\nmatter fraction $f_{\\rm DM}$ within one half-light radius $R_{\\rm e}$ for about\n6K galaxies with good kinematics spanning a wide range of morphologies and\nstellar velocity dispersion ($1.6\\lesssim \\lg\\,\\sigma_{\\rm\ne}/\\mathrm{km\\,s^{-1}}\\lesssim 2.6$). We employ two techniques to estimate\n$f_{\\rm DM}$: (i) Jeans Anisotropic Modelling (JAM), which performs dark matter\ndecomposition based on the stellar kinematics and (ii) comparing the total\ndynamical mass-to-light ratios $(M/L)_{\\rm JAM}$ and the $(M_{\\ast}/L)_{\\rm\nSPS}$ from Stellar Population Synthesis (SPS). We find that both methods\nconsistently show a significant trend of increasing $f_{\\rm DM}$ with\ndecreasing $\\sigma_{\\rm e}$, for $\\lg(\\sigma_{\\rm\ne}/\\mathrm{km\\,s^{-1}})\\lesssim2.1$ and very low $f_{\\rm DM}$ at larger\n$\\sigma_{\\rm e}$. For the 235 early-type galaxies with the best dynamical\nmodels, we explore the variation of the stellar initial mass function (IMF) by\ncomparing the stellar mass-to-light ratios $(M_{\\ast}/L)_{\\rm JAM}$ from JAM\nand SPS. We confirm that the stellar mass excess $\\alpha_{\\rm IMF}\\equiv\n(M_{\\ast}/L)_{\\rm JAM}/(M_{\\ast}/L)_{\\rm SPS}$, which reflects the IMF shape,\nincreases with $\\sigma_{\\rm e}$, in agreement with previous studies that\nreported a transition from Chabrier-like to Salpeter IMF among galaxies. We\nalso detect weak positive correlations between $\\alpha_{\\rm IMF}$ and age, but\nno correlations with metallicity ($[Z/H]$). Finally, we stack galaxy spectra\naccording to their $\\alpha_{\\rm IMF}$ to search for differences in\nIMF-sensitive spectral features (e.g. the $\\rm Na_{\\rm I}$ doublet). We only\nfind marginal evidence for such differences, which casts doubt on the validity\nof one or both methods to measure the IMF.", "positive": "The analysis of realistic Stellar Gaia mock catalogues. I. Red Clump\n Stars as tracers of the central bar: In this first paper we simulate the population of disc Red Clump stars to be\nobserved by Gaia. We generate a set of test particles and we evolve it in a 3D\nbarred Milky Way like galactic potential. We assign physical properties of the\nRed Clump trace population and a realistic 3D interstellar extinction model. We\nadd Gaia observational constraints and an error model according to the\npre-commissioning scientific performance assessments. We present and analyse\ntwo mock catalogues, offered to the community, that are an excellent test bed\nfor testing tools being developed for the future scientific exploitation of\nGaia data. The first catalogue contains stars up to Gaia G 20, while the second\nis the subset containing Gaia radial velocity data with a maximum error of\nsigmaVr=10 kms. Here we present first attempts to characterise the density\nstructure of the Galactic bar in the Gaia space of observables. The Gaia large\nerrors in parallax and the high interstellar extinction in the inner parts of\nthe Galactic disc prevent us to model the bar overdensity. This result suggests\nthe need to combine Gaia and IR data to undertake such studies. We find that IR\nphotometric distances for this Gaia sample allow us to recover the Galactic bar\norientation angle with an accuracy of approximately 5 degrees." }, { "anchor": "Do the stellar populations of the brightest two group galaxies depend on\n the magnitude gap?: We investigate how the stellar populations of the inner regions of the first\nand the second brightest group galaxies (respectively BGGs and SBGGs) vary as a\nfunction of magnitude gap, using an SDSS-based sample of 550 groups with\nelliptical BGGs. The sample is complete in redshift, luminosity and for $\\Delta\n\\mathcal{M}_{12}$ up to 2.5 mag, and contains 59 large-gap groups (LGGs, with\n$\\Delta \\mathcal{M}_{12} > 2.0$ mag). We determine ages, metallicities, and\nSFHs of BGGs and SBGGs using the STARLIGHT code with two different single\nstellar population models (which lead to important disagreements in SFHs), and\nalso compute $[\\alpha/{\\rm Fe}]$ from spectral indices. After removing the\ndependence with galaxy velocity dispersion or with stellar mass, there is no\ncorrelation with magnitude gap of BGG ages, metallicities, $[\\alpha/{\\rm Fe}]$,\nand SFHs. The lack of trends of BGG SFHs with magnitude gap suggests that BGGs\nin LGGs have undergone more mergers than those in small-gap groups, but these\nmergers are either dry or occurred at very high redshift, which in either case\nwould leave no detectable imprint in their spectra. We show that SBGGs in LGGs\nlie significantly closer to the BGGs (in projection) than galaxies with similar\nstellar masses in normal groups, which appears to be a sign of the earlier\nentry of the former into their groups. Nevertheless, the stellar population\nproperties of the SBGGs in LGGs are compatible with those of the general\npopulation of galaxies with similar stellar masses residing in normal groups.", "positive": "Comparing M31 and Milky Way Satellites: The Extended Star Formation\n Histories of Andromeda II and Andromeda XVI: We present the first comparison between the lifetime star formation histories\n(SFHs) of M31 and Milky Way (MW) satellites. Using the Advanced Camera for\nSurveys aboard the Hubble Space Telescope, we obtained deep optical imaging of\nAndromeda II (M$_{V} = -$12.0; log(M$_{\\star}$/M$_{\\odot}$) $\\sim$ 6.7) and\nAndromeda XVI (M$_{V} = -$7.5; log(M$_{\\star}$/M$_{\\odot}$) $\\sim$ 4.9)\nyielding color-magnitude diagrams that extend at least 1 magnitude below the\noldest main sequence turnoff, and are similar in quality to those available for\nthe MW companions. And II and And XVI show strikingly similar SFHs: both formed\n50-70% of their total stellar mass between 12.5 and 5 Gyr ago (z$\\sim$5-0.5)\nand both were abruptly quenched $\\sim$ 5 Gyr ago (z$\\sim$0.5). The predominance\nof intermediate age populations in And XVI makes it qualitatively different\nfrom faint companions of the MW and clearly not a pre-reionization fossil.\nNeither And II nor And XVI appears to have a clear analog among MW companions,\nand the degree of similarity in the SFHs of And II and And XVI is not seen\namong comparably faint-luminous pairs of MW satellites. These findings provide\nhints that satellite galaxy evolution may vary substantially among hosts of\nsimilar stellar mass. Although comparably deep observations of more M31\nsatellites are needed to further explore this hypothesis, our results underline\nthe need for caution when interpreting satellite galaxies of an individual\nsystem in a broader cosmological context." }, { "anchor": "Frequency of Tidal Features Correlates with Age and Internal Structure\n of Early-type Galaxies: Previous studies suggest that compact young early-type galaxies (ETGs) were\nformed by recent mergers. However, it has not yet been revealed whether tidal\nfeatures that are direct evidence of recent mergers are detected frequently\naround compact young ETGs. Here, we investigate how the fraction of ETGs having\ntidal features ($f_{T}$) depends on age and internal structure (compactness,\ncolor gradient, and dust lanes) of ETGs, using 650 ETGs with $M_r\\le-19.5$ in\n$0.015\\le z\\le0.055$ that are in deep coadded images of the Stripe 82 region of\nthe Sloan Digital Sky Survey. We find that tidal features are more frequent in\nyounger ETGs and more compact ETGs, so that compact young ETGs with ages\n$\\lesssim6$ Gyr have high $f_{T}$ of $\\sim0.7$ compared to their less compact\nor old counterparts with ages $\\gtrsim9$ Gyr that have $f_{T}\\lesssim0.1$.\nAmong compact young ETGs, those with blue cores have $\\sim3$ times higher\n$f_{T}$ than those with red cores. In addition, ETGs with dust lanes have\n$\\sim4$ times higher $f_{T}$ than those without dust lanes. Our results provide\ndirect evidence that compact young ETGs especially with blue cores and ETGs\nwith dust lanes are involved in recent mergers. Based on our results and\nseveral additional assumptions, we roughly estimate the typical visible time of\ntidal features after a merger, which is $\\sim3$ Gyr in the depth of the Stripe\n82 coadded images.", "positive": "On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in\n Nearby Star-forming Galaxies: We use medium-resolution Keck/Echellette Spectrograph and Imager spectroscopy\nof bright quasars to study cool gas traced by CaII 3934,3969 and NaI 5891,5897\nabsorption in the interstellar/circumgalactic media of 21 foreground\nstar-forming galaxies at redshifts 0.03 < z < 0.20 with stellar masses 7.4 <\nlog M_*/M_sun < 10.6. The quasar-galaxy pairs were drawn from a unique sample\nof Sloan Digital Sky Survey quasar spectra with intervening nebular emission,\nand thus have exceptionally close impact parameters (R_perp < 13 kpc). The\nstrength of this line emission implies that the galaxies' star formation rates\n(SFRs) span a broad range, with several lying well above the star-forming\nsequence. We use Voigt profile modeling to derive column densities and\ncomponent velocities for each absorber, finding that column densities N(CaII) >\n10^12.5 cm^-2 (N(NaI) > 10^12.0 cm^-2) occur with an incidence f_C(CaII) =\n0.63^+0.10_-0.11 (f_C(NaI) = 0.57^+0.10_-0.11). We find no evidence for a\ndependence of f_C or the rest-frame equivalent widths W_r(CaII K) or W_r(NaI\n5891) on R_perp or M_*. Instead, W_r(CaII K) is correlated with local SFR at\n>3sigma significance, suggesting that CaII traces star formation-driven\noutflows. While most of the absorbers have velocities within +/-50 km/s of the\nhost redshift, their velocity widths (characterized by Delta v_90) are\nuniversally 30-177 km/s larger than that implied by tilted-ring modeling of the\nvelocities of interstellar material. These kinematics must trace galactic\nfountain flows and demonstrate that they persist at R_perp > 5 kpc. Finally, we\nassess the relationship between dust reddening and W_r(CaII K) (W_r(NaI 5891)),\nfinding that 33% (24%) of the absorbers are inconsistent with the best-fit\nMilky Way E(B-V)-W_r relations at >3sigma significance." }, { "anchor": "Accretion and star formation in 'radio-quiet' quasars: Radio observations allow us to identify a wide range of active galactic\nnuclei (AGN), which play a significant role in the evolution of galaxies.\nAmongst AGN at low radio-luminosities is the 'radio-quiet' quasar (RQQ)\npopulation, but how they contribute to the total radio emission is under\ndebate, with previous studies arguing that it is predominantly through star\nformation. In this talk, SVW summarised the results of recent papers on RQQs,\nincluding the use of far-infrared data to disentangle the radio emission from\nthe AGN and that from star formation. This provides evidence that black-hole\naccretion, instead, dominates the radio emission in RQQs. In addition, we find\nthat this accretion-related emission is correlated with the optical luminosity\nof the quasar, whilst a weaker luminosity-dependence is evident for the radio\nemission connected with star formation. What remains unclear is the process by\nwhich this accretion-related emission is produced. Understanding this for RQQs\nwill then allow us to investigate how this type of AGN influences its\nsurroundings. Such studies have important implications for modelling AGN\nfeedback, and for determining the accretion and star-formation histories of the\nUniverse.", "positive": "New constraints on red-spiral galaxies from their kinematics in clusters\n of galaxies: The distributions of the pairwise line-of-sight velocity between galaxies and\ntheir host clusters are segregated according to the galaxy's colour and\nmorphology. We investigate the velocity distribution of red-spiral galaxies,\nwhich represents a rare population within galaxy clusters. We find that the\nprobability distribution function of the pairwise line-of-sight velocity\n$v_{\\rm{los}}$ between red-spiral galaxies and galaxy clusters has a dip at\n$v_{\\rm{los}} = 0$, which is a very odd feature, at 93\\% confidence level. To\nunderstand its origin, we construct a model of the phase space distribution of\ngalaxies surrounding galaxy clusters in three-dimensional space by using\ncosmological $N$-body simulations. We adopt a two component model that consists\nof the infall component, which corresponds to galaxies that are now falling\ninto galaxy clusters, and the splashback component, which corresponds to\ngalaxies that are on their first (or more) orbit after falling into galaxy\nclusters. We find that we can reproduce the distribution of the line-of-sight\nvelocity of red-spiral galaxies with the dip with a very simple assumption that\nred-spiral galaxies reside predominantly in the infall component, regardless of\nthe choice of the functional form of their spatial distribution. Our results\nconstrain the quenching timescale of red-spiral galaxies to a few Gyrs, and the\nradius where the morphological transformation is effective as $r \\sim 0.2\nh^{-1} \\rm{Mpc}$." }, { "anchor": "Discovery of a pseudobulge galaxy launching powerful relativistic jets: Supermassive black holes launching plasma jets at close to speed of light,\nproducing gamma-rays, have ubiquitously been found to be hosted by massive\nelliptical galaxies. Since elliptical galaxies are generally believed to be\nbuilt through galaxy mergers, active galactic nuclei (AGN) launching\nrelativistic jets are associated to the latest stages of galaxy evolution. We\nhave discovered a pseudo-bulge morphology in the host galaxy of the gamma-ray\nAGN PKS 2004-447. This is the first gamma-ray emitter radio loud AGN found to\nbe launched from a system where both black hole and host galaxy have been\nactively growing via secular processes. This is evidence for an alternative\nblack hole-galaxy co-evolutionary path to develop powerful relativistic jets\nthat is not merger-driven.", "positive": "The second Herschel-ATLAS Data Release - III: optical and near-infrared\n counterparts in the North Galactic Plane field: This paper forms part of the second major public data release of the Herschel\nAstrophysical Terahertz Large Area Survey (H-ATLAS). In this work, we describe\nthe identification of optical and near-infrared counterparts to the\nsubmillimetre detected sources in the $177$ deg$^2$ North Galactic Plane (NGP)\nfield. We used the likelihood ratio method to identify counterparts in the\nSloan Digital Sky Survey and in the UKIRT Imaging Deep Sky Survey within a\nsearch radius of $10$ arcsec of the H-ATLAS sources with a $4\\sigma$ detection\nat $250 \\, \\mu$m. We obtained reliable ($R \\ge 0.8 $) optical counterparts with\n$r< 22.4$ for 42429 H-ATLAS sources ($37.8$ per cent), with an estimated\ncompleteness of $71.7$ per cent and a false identification rate of $4.7$ per\ncent. We also identified counterparts in the near-infrared using deeper\n$K$-band data which covers a smaller $\\sim25$ deg$^2$. We found reliable\nnear-infrared counterparts to $61.8$ per cent of the $250$-$\\mu$m-selected\nsources within that area. We assessed the performance of the likelihood ratio\nmethod to identify optical and near-infrared counterparts taking into account\nthe depth and area of both input catalogues. Using catalogues with the same\nsurface density of objects in the overlapping $\\sim25$ deg$^2$ area, we\nobtained that the reliable fraction in the near-infrared ($54.8$ per cent) is\nsignificantly higher than in the optical ($36.4$ per cent). Finally, using deep\nradio data which covers a small region of the NGP field, we found that $80 -\n90$ per cent of our reliable identifications are correct." }, { "anchor": "Constraints on stellar rotation from the evolution of Sr and Ba in the\n Galactic halo: Recent studies show that the chemical evolution of Sr and Ba in the Galaxy\ncan be explained if different production sites, hosting r- and s-processes, are\ntaken into account. However, the question of unambiguously identifying these\nsites is still unsolved. Massive stars are shown to play an important role in\nthe production of s-material if rotation is considered. In this work, we study\nin detail the contribution of rotating massive stars to the production of Sr\nand Ba, in order to explain their chemical evolution, but also to constrain the\nrotational behaviour of massive stars. A stochastic chemical evolution model\nwas employed to reproduce the enrichment of the Galactic halo. We developed new\nmethods for model-data comparison which help to objectively compare the\nstochastic results to the observations. We employed these methods to estimate\nthe value of free parameters which describe the rotation of massive stars,\nassumed to be dependent on the stellar metallicity. We constrain the parameters\nusing the observations for Sr and Ba. Employing these parameters for rotating\nmassive stars in our stochastic model, we are able to correctly reproduce the\nchemical evolution of Sr and Ba, but also Y, Zr and La. The data supports a\ndecrease of both the mean rotational velocities and their dispersion with\nincreasing metallicity. Our results show that a metallicity-dependent rotation\nis a necessary assumption to explain the s-process in massive stars. Our novel\nmethods of model-data comparison represent a promising tool for future galactic\nchemical evolution studies.", "positive": "Photoevaporating PDR models with the Hydra PDR Code: Recent Herschel and ALMA observations of Photodissociation Regions (PDRs)\nhave revealed the presence of a high thermal pressure (P ~ 10^7-10^8 K cm-3)\nthin compressed layer at the PDR surface where warm molecular tracer emission\n(e.g. CH+, SH+, high-J CO, H2,...) originate. These high pressures (unbalanced\nby the surrounding environment) and a correlation between pressure and incident\nFUV field (G0) seem to indicate a dynamical origin with the radiation field\nplaying an important role in driving the dynamics. We investigate whether\nphotoevaporation of the illuminated edge of a molecular cloud could explain\nthese high pressures and pressure-UV field correlation. We developed a 1D\nhydrodynamical PDR code coupling hydrodynamics, EUV and FUV radiative transfer\nand time-dependent thermo-chemical evolution. We applied it to a 1D\nplane-parallel photoevaporation scenario where a UV-illuminated molecular cloud\ncan freely evaporate in a surrounding low-pressure medium. We find that\nphotoevaporation can produce high thermal pressures and the observed P-G0\ncorrelation, almost independently from the initial gas density. In addition, we\nfind that constant-pressure PDR models are a better approximation to the\nstructure of photoevaporating PDRs than constant-density PDR models, although\nmoderate pressure gradients are present. Strong density gradients from the\nmolecular to the neutral atomic region are found, which naturally explain the\nlarge density contrasts (1-2 orders of magnitude) derived from observations of\ndifferent tracers. The photoevaporating PDR is preceded by a low velocity shock\n(a few km/s) propagating into the molecular cloud. Photoevaporating PDR models\noffer a promising explanation to the recent observational evidence of dynamical\neffects in PDRs." }, { "anchor": "The Chemical/Dynamical Evolution of the Galactic Bulge: The last decade has seen apparent dramatic progress in large spectroscopic\ndatasets aimed at the study of the Galactic bulge. We consider remaining\nproblems that appear to be intractable with the existing data, including\nimportant issues such as whether the bulge and thick disk actually show\ndistinct chemistry, and apparent dramatic changes in morphology at Solar\nmetallicity, as well as large scale study of the heavy elements (including\nr-process) in the bulge. Although infrared spectroscopy is powerful, the lack\nof heavy element atomic transitions in the infrared renders impossible any\nsurvey of heavy elements from such data. We argue that uniform, high S/N, high\nresolution data in the optical offer an outstanding opportunity to resolve\nthese problems and explore other populations in the bulge, such as RR Lyrae and\nhot HB stars.", "positive": "Planck 2013 results. XI. All-sky model of thermal dust emission: This paper presents an all-sky model of dust emission from the Planck 857,\n545 and 353 GHz, and IRAS 100 micron data. Using a modified black-body fit to\nthe data we present all-sky maps of the dust optical depth, temperature, and\nspectral index over the 353-3000 GHz range. This model is a tight\nrepresentation of the data at 5 arc min. It shows variations of the order of 30\n% compared with the widely-used model of Finkbeiner, Davis, and Schlegel. The\nPlanck data allow us to estimate the dust temperature uniformly over the whole\nsky, providing an improved estimate of the dust optical depth compared to\nprevious all-sky dust model, especially in high-contrast molecular regions. An\nincrease of the dust opacity at 353 GHz, tau_353/N_H, from the diffuse to the\ndenser interstellar medium (ISM) is reported. It is associated with a decrease\nin the observed dust temperature, T_obs, that could be due at least in part to\nthe increased dust opacity. We also report an excess of dust emission at HI\ncolumn densities lower than 10^20 cm^-2 that could be the signature of dust in\nthe warm ionized medium. In the diffuse ISM at high Galactic latitude, we\nreport an anti-correlation between tau_353/N_H and T_obs while the dust\nspecific luminosity, i.e., the total dust emission integrated over frequency\n(the radiance) per hydrogen atom, stays about constant. The implication is that\nin the diffuse high-latitude ISM tau_353 is not as reliable a tracer of dust\ncolumn density as we conclude it is in molecular clouds where the correlation\nof tau_353 with dust extinction estimated using colour excess measurements on\nstars is strong. To estimate Galactic E(B-V) in extragalactic fields at high\nlatitude we develop a new method based on the thermal dust radiance, instead of\nthe dust optical depth, calibrated to E(B-V) using reddening measurements of\nquasars deduced from Sloan Digital Sky Survey data." }, { "anchor": "The Green Valley is a Red Herring: Galaxy Zoo reveals two evolutionary\n pathways towards quenching of star formation in early- and late-type galaxies: We use SDSS+\\textit{GALEX}+Galaxy Zoo data to study the quenching of star\nformation in low-redshift galaxies. We show that the green valley between the\nblue cloud of star-forming galaxies and the red sequence of quiescent galaxies\nin the colour-mass diagram is not a single transitional state through which\nmost blue galaxies evolve into red galaxies. Rather, an analysis that takes\nmorphology into account makes clear that only a small population of blue\nearly-type galaxies move rapidly across the green valley after the morphologies\nare transformed from disk to spheroid and star formation is quenched rapidly.\nIn contrast, the majority of blue star-forming galaxies have significant disks,\nand they retain their late-type morphologies as their star formation rates\ndecline very slowly. We summarize a range of observations that lead to these\nconclusions, including UV-optical colours and halo masses, which both show a\nstriking dependence on morphological type. We interpret these results in terms\nof the evolution of cosmic gas supply and gas reservoirs. We conclude that\nlate-type galaxies are consistent with a scenario where the cosmic supply of\ngas is shut off, perhaps at a critical halo mass, followed by a slow exhaustion\nof the remaining gas over several Gyr, driven by secular and/or environmental\nprocesses. In contrast, early-type galaxies require a scenario where the gas\nsupply and gas reservoir are destroyed virtually instantaneously, with rapid\nquenching accompanied by a morphological transformation from disk to spheroid.\nThis gas reservoir destruction could be the consequence of a major merger,\nwhich in most cases transforms galaxies from disk to elliptical morphology, and\nmergers could play a role in inducing black hole accretion and possibly AGN\nfeedback.", "positive": "C$_2$H observations toward the Orion Bar: C$_2$H is one of the first radicals to be detected in the interstellar\nmedium. Its higher rotational transitions have recently become available with\nthe Herschel Space Observatory. We aim to constrain the physical parameters of\nthe C$_2$H emitting gas toward the Orion Bar. We analyse the C$_2$H line\nintensities measured toward the Orion Bar CO$^+$ Peak and Herschel/HIFI maps of\nC$_2$H, CH, and HCO$^+$, and a NANTEN map of [CI]. We interpret the observed\nC$_2$H emission using radiative transfer and PDR models. Five rotational\ntransitions of C$_2$H have been detected in the HIFI frequency range toward the\nCO$^+$ peak. A single component rotational diagram gives a rotation temperature\nof ~64 K and a beam-averaged C$_2$H column density of 4$\\times$10$^{13}$\ncm$^{-2}$. The measured transitions cannot be explained by any single parameter\nmodel. According to a non-LTE model, most of the C$_2$H column density produces\nthe lower-$N$ C$_2$H transitions and traces a warm ($T_{\\rm{kin}}$ ~ 100-150 K)\nand dense ($n$(H$_2$)~10$^5$-10$^6$ cm$^{-3}$) gas. A small fraction of the\nC$_2$H column density is required to reproduce the intensity of the highest-$N$\ntransitions ($N$=9-8 and N=10-9) originating from a high density\n($n$(H$_2$)~5$\\times$10$^6$ cm$^{-3}$) hot ($T_{\\rm{kin}}$ ~ 400 K) gas. The\ntotal beam-averaged C$_2$H column density in the model is 10$^{14}$ cm$^{-2}$.\nBoth the non-LTE radiative transfer model and a simple PDR model representing\nthe Orion Bar with a plane-parallel slab of gas and dust suggest, that C$_2$H\ncannot be described by a single pressure component, unlike the reactive ion\nCH$^+$, which was previously analysed toward the Orion Bar CO$^+$ peak. The\nphysical parameters traced by the higher rotational transitions\n($N$=6-5,...,10-9) of C$_2$H may be consistent with the edges of dense clumps\nexposed to UV radiation near the ionization front of the Orion Bar." }, { "anchor": "Magnetism in the nearby galaxy M33: Using high-resolution data of the linearly polarized intensity and\npolarization angle at 3.6, 6.2, and 20 cm together with a 3-D model of the\nregular magnetic field, we study variations of the structure, strength, and\nenergy density of the magnetic field in the Scd galaxy M33. The regular\nmagnetic field consists of a horizontal component (represented by an\naxisymmetric mode from 1 to 3 kpc radius and a superposition of axisymmetric\nand bisymmetric modes from 3 to 5 kpc radius) and a vertical component.\nHowever, the inferred `vertical field' may be partly due to a galactic warp. We\nestimate the average total and regular magnetic field strengths as ~ 6.4 and\n2.5 $\\mu$G, respectively. Generation of interstellar magnetic fields by\nturbulent gas motion in M33 is indicated as the turbulent and magnetic energy\ndensities are about equal.", "positive": "VISION - Vienna survey in Orion I. VISTA Orion A Survey: Orion A hosts the nearest massive star factory, thus offering a unique\nopportunity to resolve the processes connected with the formation of both low-\nand high-mass stars. Here we present the most detailed and sensitive\nnear-infrared (NIR) observations of the entire molecular cloud to date. With\nthe unique combination of high image quality, survey coverage, and sensitivity,\nour NIR survey of Orion A aims at establishing a solid empirical foundation for\nfurther studies of this important cloud. In this first paper we present the\nobservations, data reduction, and source catalog generation. To demonstrate the\ndata quality, we present a first application of our catalog to estimate the\nnumber of stars currently forming inside Orion A and to verify the existence of\na more evolved young foreground population. We used the European Southern\nObservatory's (ESO) Visible and Infrared Survey Telescope for Astronomy (VISTA)\nto survey the entire Orion A molecular cloud in the NIR $J, H$, and $K_S$\nbands, covering a total of $\\sim$18.3 deg$^2$. We implemented all data\nreduction recipes independently of the ESO pipeline. Estimates of the young\npopulations toward Orion A are derived via the $K_S$-band luminosity function.\nOur catalog (799995 sources) increases the source counts compared to the Two\nMicron All Sky Survey by about an order of magnitude. The 90% completeness\nlimits are 20.4, 19.9, and 19.0 mag in $J, H$, and $K_S$, respectively. The\nreduced images have 20% better resolution on average compared to pipeline\nproducts. We find between 2300 and 3000 embedded objects in Orion A and confirm\nthat there is an extended foreground population above the Galactic field, in\nagreement with previous work. The Orion A VISTA catalog represents the most\ndetailed NIR view of the nearest massive star-forming region and provides a\nfundamental basis for future studies of star formation processes toward Orion." }, { "anchor": "Constraining FeLoBAL outflows from absorption line variability: FeLoBALs are a rare class of quasar outflows with low-ionization broad\nabsorption lines (BALs), large column densities, and potentially large kinetic\nenergies that might be important for `feedback' to galaxy evolution. In order\nto probe the physical properties of these outflows, we conducted a\nmultiple-epoch, absorption line variability study of 12 FeLoBAL quasars\nspanning a redshift range between 0.7 and 1.9 over rest frame time-scales of\napproximately 10 d to 7.6 yr. We detect absorption line variability with\ngreater than 8 sigma confidence in 3 out of the 12 sources in our sample over\ntime-scales of 0.6 to 7.6 yr. Variable wavelength intervals are associated with\nground and excited state Fe II multiplets, the Mg II 2796, 2803 doublet, Mg I\n2852, and excited state Ni II multiplets. The observed variability along with\nevidence of saturation in the absorption lines favors transverse motions of gas\nacross the line of sight (LOS) as the preferred scenario, and allows us to\nconstrain the outflow distance from the supermassive black hole (SMBH) to be\nless than 69, 7, and 60 pc for our three variable sources. In combination with\nother studies, these results suggest that the outflowing gas in FeLoBAL quasars\nresides on a range of scales and includes matter within tens of parsecs of the\ncentral source.", "positive": "An analytical model for the evolution of starless cores I: The\n constant-mass case: We propose an analytical model for the quasistatic evolution of starless\ncores confined by a constant external pressure, assuming that cores are\nisothermal and obey a spherically-symmetric density distribution. We model core\nevolution for Plummer-like and Gaussian density distributions in the adiabatic\nand isothermal limits, assuming Larson-like dissipation of turbulence. We model\nthe variation in the terms in the virial equation as a function of core\ncharacteristic radius, and determine whether cores are evolving toward virial\nequilibrium or gravitational collapse. We ignore accretion onto cores in the\ncurrent study. We discuss the different behaviours predicted by the isothermal\nand adiabatic cases, and by our choice of index for the size-linewidth\nrelation, and suggest a means of parameterising the magnetic energy term in the\nvirial equation. We model the evolution of the set of cores observed by Pattle\net al. (2015) in the L1688 region of Ophiuchus in the 'virial plane'. We find\nthat not all virially-bound and pressure-confined cores will evolve to become\ngravitationally bound, with many instead contracting to virial equilibrium with\ntheir surroundings, and find an absence of gravitationally-dominated and\nvirially-unbound cores. We hypothesise a 'starless core desert' in this\nquadrant of the virial plane, which may result from cores initially forming as\npressure-confined objects. We conclude that a virially-bound and\npressure-confined core will not necessarily evolve to become gravitationally\nbound, and thus cannot be considered prestellar. A core can only be\ndefinitively considered prestellar (collapsing to form an individual stellar\nsystem) if it is gravitationally unstable." }, { "anchor": "The X-Shaped Milky Way Bulge in OGLE-III Photometry and in N-Body Models: We model the split red clump of the Galactic bulge in OGLE-III photometry,\nand compare the results to predictions from two N-body models. Our analysis\nyields precise maps of the brightness of the two red clumps, the fraction of\nstars in the more distant peak, and their combined surface density. We compare\nthe observations to predictions from two N-body models previously used in the\nliterature. Both models correctly predict several features as long as one\nassumes an angle $\\alpha_{\\rm{Bar}} \\approx 30^{\\circ}$ between the Galactic\nbar's major axis and the line of sight to the Galactic centre. In particular\nthat the fraction of stars in the faint red clump should decrease with\nincreasing longitude. The biggest discrepancies between models and data are in\nthe rate of decline of the combined surface density of red clump stars toward\nnegative longitudes and of the brightness difference between the two red clumps\ntoward positive longitudes, with neither discrepancy exceeding $\\sim$25% in\namplitude. Our analysis of the red giant luminosity function also yields an\nestimate of the red giant branch bump parameters toward these high-latitude\nfields, and evidence for a high rate ($\\sim$25%) of disk contamination in the\nbulge at the colour and magnitude of the red clump, with the disk contamination\nrate increasing toward sightlines further distant from the plane.", "positive": "Star Formation Variability as a Probe for the Baryon Cycle within\n Galaxies: We investigate the connection of the regulation of star formation and the\ncycling of baryons within and in and out of galaxies. We use idealized\nnumerical simulations of Milky Way-mass galaxies, in which we systemically vary\nthe galaxy morphology (bulge-to-total mass ratio) and stellar feedback strength\n(total eight setups with 80 simulations). By following individual gas parcels\nthrough the disk, spiral arms, and massive star-forming clumps, we quantify how\ngas moves and oscillates through the different phases of the interstellar\nmedium (ISM) and forms stars. We show that the residence time of gas in the\ndense ISM phase ($\\tau_{\\rm SF}$), the nature of spiral arms (strength,\nnumber), and the clump properties (number, mass function, and young star\nfraction) depend on both the galaxy morphology and stellar feedback. Based on\nthese results, we quantify signatures of the baryon cycle within galaxies using\nthe temporal and spatial power spectrum density (PSD) of the star formation\nhistory (SFH). Stronger stellar feedback leads to more bursty star formation\nwhile the correlation timescale of the SFH is longer, because stronger feedback\ndissolves the dense, star-forming ISM phase, leading to a more homogeneous ISM\nand a decrease in $\\tau_{\\rm SF}$. The bulge strength has a similar effect: the\ndeep gravitational potential in a bulge-dominant galaxy imposes a strong shear\nforce that effectively breaks apart gas clumps in the ISM; this subsequently\ninhibits the fragmentation of cool gas and therefore the star formation in the\ndisk, leading to a decrease in the spatial power on scales of $\\sim$ 1 kpc. We\nconclude that measurements of the temporal and spatial PSD of the SFH can\nprovide constraints on the baryon cycle and the star formation process." }, { "anchor": "Probing the innermost regions of AGN jets and their magnetic fields with\n RadioAstron II. Observations of 3C 273 at minimum activity: RadioAstron is a 10 m orbiting radio telescope mounted on the Spektr-R\nsatellite, launched in 2011, performing Space Very Long Baseline Interferometry\n(SVLBI) observations supported by a global ground array of radio telescopes.\nWith an apogee of about 350 000 km, it is offering for the first time the\npossibility to perform {\\mu}as-resolution imaging in the cm-band. We present\nobservations at 22 GHz of 3C 273, performed in 2014, designed to reach a\nmaximum baseline of approximately nine Earth diameters. Reaching an angular\nresolution of 0.3 mas, we study a particularly low-activity state of the\nsource, and estimate the nuclear region brightness temperature, comparing with\nthe extreme one detected one year before during the RadioAstron early science\nperiod. We also make use of the VLBA-BU-BLAZAR survey data, at 43 GHz, to study\nthe kinematics of the jet in a 1.5-year time window. We find that the nuclear\nbrightness temperature is two orders of magnitude lower than the exceptionally\nhigh value detected in 2013 with RadioAstron at the same frequency (1.4x10^13\nK, source-frame), and even one order of magnitude lower than the equipartition\nvalue. The kinematics analysis at 43 GHz shows that a new component was ejected\n2 months after the 2013 epoch, visible also in our 22 GHz map presented here.\nConsequently this was located upstream of the core during the brightness\ntemperature peak. These observations confirm that the previously detected\nextreme brightness temperature in 3C 273, exceeding the inverse Compton limit,\nis a short-lived phenomenon caused by a temporary departure from equipartition.\nThus, the availability of interferometric baselines capable of providing\n{\\mu}as angular resolution does not systematically imply measured brightness\ntemperatures over the known physical limits for astrophysical sources.", "positive": "LOFAR/H-ATLAS: A deep low-frequency survey of the Herschel-ATLAS North\n Galactic Pole field: We present LOFAR High-Band Array (HBA) observations of the Herschel-ATLAS\nNorth Galactic Pole survey area. The survey we have carried out, consisting of\nfour pointings covering around 142 square degrees of sky in the frequency range\n126--173 MHz, does not provide uniform noise coverage but otherwise is\nrepresentative of the quality of data to be expected in the planned LOFAR\nwide-area surveys, and has been reduced using recently developed `facet\ncalibration' methods at a resolution approaching the full resolution of the\ndatasets ($\\sim 10 \\times 6$ arcsec) and an rms off-source noise that ranges\nfrom 100 $\\mu$Jy beam$^{-1}$ in the centre of the best fields to around 2 mJy\nbeam$^{-1}$ at the furthest extent of our imaging. We describe the imaging,\ncataloguing and source identification processes, and present some initial\nscience results based on a 5-$\\sigma$ source catalogue. These include (i) an\ninitial look at the radio/far-infrared correlation at 150 MHz, showing that\nmany Herschel sources are not yet detected by LOFAR; (ii) number counts at 150\nMHz, including, for the first time, observational constraints on the numbers of\nstar-forming galaxies; (iii) the 150-MHz luminosity functions for active and\nstar-forming galaxies, which agree well with determinations at higher\nfrequencies at low redshift, and show strong redshift evolution of the\nstar-forming population; and (iv) some discussion of the implications of our\nobservations for studies of radio galaxy life cycles." }, { "anchor": "SNITCH: Seeking a simple, informative star formation history inference\n tool: Deriving a simple, analytic galaxy star formation history (SFH) using\nobservational data is a complex task without the proper tool to hand. We\ntherefore present SNITCH, an open source code written in Python, developed to\nquickly (~2 minutes) infer the parameters describing an analytic SFH model from\nthe emission and absorption features of a galaxy spectrum dominated by star\nformation gas ionisation. SNITCH uses the Flexible Stellar Population Synthesis\nmodels of Conroy et al. (2009), the MaNGA Data Analysis Pipeline and a Markov\nChain Monte Carlo method in order to infer three parameters (time of quenching,\nrate of quenching and model metallicity) which best describe an exponentially\ndeclining quenching history. This code was written for use on the MaNGA\nspectral data cubes but is customisable by a user so that it can be used for\nany scenario where a galaxy spectrum has been obtained, and adapted to infer a\nuser-defined analytic SFH model for specific science cases. Herein we outline\nthe rigorous testing applied to SNITCH and show that it is both accurate and\nprecise at deriving the SFH of a galaxy spectra. The tests suggest that SNITCH\nis sensitive to the most recent epoch of star formation but can also trace the\nquenching of star formation even if the true decline does not occur at an\nexponential rate. With the use of both an analytical SFH and only five spectral\nfeatures, we advocate that this code be used as a comparative tool across a\nlarge population of spectra, either for integral field unit data cubes or\nacross a population of galaxy spectra.", "positive": "A Direct Stellar Metallicity Determination in the Disk of the Maser\n Galaxy NGC4258: We present the first direct determination of a stellar metallicity in the\nspiral galaxy NGC4258 (D=7.6 Mpc) based on the quantitative analysis of a\nlow-resolution (~5 AE) Keck LRIS spectrum of a blue supergiant star located in\nits disk. A determination of stellar metallicity in this galaxy is important\nfor the absolute calibration of the Cepheid Period-Luminosity relation as an\nanchor for the extragalactic distance scale and for a better characterization\nof its dependence as a function of abundance. We find a value 0.2 dex lower\nthan solar metallicity at a galactocentric distance of 8.7 kpc, in agreement\nwith recent HII region studies using the weak forbidden auroral oxygen line at\n4363 AE. We determine the effective stellar temperature, gravity, luminosity\nand line-of-sight extinction of the blue supergiant being studied. We show that\nit fits well on the flux-weighted gravity--luminosity relation (FGLR),\nstrengthening the potential of this method as a new extragalactic distance\nindicator." }, { "anchor": "Excited-State OH Masers in the Water Fountain Source IRAS 18460-0151: Water fountain objects are generally defined as \"evolved stars with low to\nintermediate initial mass accompanied by high-velocity molecular jets\ndetectable in the 22.235 GHz H$_2$O maser line\". They are the key objects of\nunderstanding the morphological transitions of circumstellar envelopes during\nthe post asymptotic giant branch phase. Masers are useful tools to trace the\nkinematic environments of the circumstellar envelopes. In this letter we report\nthe discovery of exceptionally uncommon excited-state hydroxyl (ex-OH) masers\nat 4660 and 6031 MHz toward the water fountain source IRAS 18460-0151. These\nare the brightest ex-OH masers discovered in late-type objects to date. To the\nbest of our knowledge, prior to the current work, no evolved stellar object has\nbeen observed in the 4660 MHz ex-OH maser line. The ground-state hydroxyl\n(g-OH) masers at 1612 and 1665 MHz are also observed. The velocity components\nof the 4660 MHz ex-OH maser line and the much weaker 1665 MHz g-OH maser line\nall can be seen in the 1612 MHz g-OH maser line profile. The blue-shifted\ncomponents of the three masers are more intense than the red-shifted ones, in\ncontrast to the ex-OH maser line at 6031 MHz. The relevance of the behaviors of\nthe ex-OH masers to the circumstellar environments is unclear.", "positive": "Preferred alignments of angular momentum vectors of galaxies in six\n dynamically unstable Abell clusters: A spatial orientation of angular momentum vectors of galaxies in six\ndynamically unstable Abell clusters (S1171, S0001, A1035, A1373, A1474 and\nA4053) is studied. For this, two-dimensional observed parameters (e.g.,\npositions, diameters, position angles) are converted into three-dimensional\nrotation axes of the galaxy using `position angle - inclination' method. The\nexpected isotropic distribution curves for angular momentum vectors are\nobtained by performing random simulations. The observed and expected\ndistributions are compared using several statistical tests. No preferred\nalignments of angular momentum vectors of galaxies are noticed in all six\ndynamically unstable clusters supporting hierarchy model of galaxy formation.\nThese clusters have a larger value of velocity dispersion. However, local\neffects are noticed in the clusters that have substructures in the 1D-3D number\ndensity maps." }, { "anchor": "Mrk 71/NGC 2366: The nearest Green Pea analog: We present the remarkable discovery that the dwarf irregular galaxy NGC 2366\nis an excellent analog of the Green Pea (GP) galaxies, which are characterized\nby extremely high ionization parameters. The similarities are driven\npredominantly by the giant H II region Markarian 71 (Mrk 71). We compare the\nsystem with GPs in terms of morphology, excitation properties, specific\nstar-formation rate, kinematics, absorption of low-ionization species,\nreddening, and chemical abundance, and find consistencies throughout. Since\nextreme GPs are associated with both candidate and confirmed Lyman continuum\n(LyC) emitters, Mrk 71/NGC 2366 is thus also a good candidate for LyC escape.\nThe spatially resolved data for this object show a superbubble blowout\ngenerated by mechanical feedback from one of its two super star clusters\n(SSCs), Knot B, while the extreme ionization properties are driven by the <1\nMyr-old, enshrouded SSC Knot A, which has ~ 10 times higher ionizing\nluminosity. Very massive stars (> 100 Msun) may be present in this remarkable\nobject. Ionization-parameter mapping indicates the blowout region is optically\nthin in the LyC, and the general properties also suggest LyC escape in the line\nof sight. Mrk 71/NGC 2366 does differ from GPs in that it is 1 - 2 orders of\nmagnitude less luminous. The presence of this faint GP analog and candidate LyC\nemitter (LCE) so close to us suggests that LCEs may be numerous and\ncommonplace, and therefore could significantly contribute to the cosmic\nionizing budget. Mrk 71/NGC 2366 offers an unprecedentedly detailed look at the\nviscera of a candidate LCE, and could clarify the mechanisms of LyC escape.", "positive": "ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870\n microns: (Abridged) Studying continuum emission from interstellar dust is essential to\nlocating and characterizing the highest density regions in the interstellar\nmedium. In particular, the early stages of massive star formation remain poorly\nunderstood. Our goal is to produce a large-scale, systematic database of\nmassive pre- and proto-stellar clumps in the Galaxy, to understand how and\nunder what conditions star formation takes place. A well characterized sample\nof star-forming sites will deliver an evolutionary sequence and a mass function\nof high-mass, star-forming clumps. This systematic survey at submm wavelengths\nalso represents a preparatory work for Herschel and ALMA. The APEX telescope is\nideally located to observe the inner Milky Way. The Large APEX Bolometer Camera\n(LABOCA) is a 295-element bolometer array observing at 870 microns, with a beam\nsize of 19\". Taking advantage of its large field of view (11.4') and excellent\nsensitivity, we started an unbiased survey of the Galactic Plane, with a noise\nlevel of 50-70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy\n(ATLASGAL). As a first step, we covered 95 sq. deg. These data reveal 6000\ncompact sources brighter than 0.25 Jy, as well as extended structures, many of\nthem filamentary. About two thirds of the compact sources have no bright\ninfrared counterpart, and some of them are likely to correspond to the\nprecursors of (high-mass) proto-stars or proto-clusters. Other compact sources\nharbor hot cores, compact HII regions or young embedded clusters. Assuming a\ntypical distance of 5 kpc, most sources are clumps smaller than 1 pc with\nmasses from a few 10 to a few 100 M_sun. In this introductory paper, we show\npreliminary results from these ongoing observations, and discuss the\nperspectives of the survey." }, { "anchor": "A Deep Near-Infrared [Fe II]+[Si I] Emission Line Image of the Supernova\n Remnant Cassiopeia A: We present a long-exposure (~10 hr) image of the supernova (SN) remnant\nCassiopeia A (Cas A) obtained with the UKIRT 3.8-m telescope using a narrow\nband filter centered at 1.644 um emission. The passband contains [Fe II] 1.644\num and [Si I] 1.645 um lines, and our `deep [Fe II]+[Si I] image' provides an\nunprecedented panoramic view of Cas A, showing both shocked and unshocked SN\nejecta together with shocked circumstellar medium at subarcsec (~0.7 arcsec or\n0.012 pc) resolution. The diffuse emission from the unshocked SN ejecta has a\nform of clumps, filaments, and arcs, and their spatial distribution correlates\nwell with that of the Spitzer [Si II] infrared emission, suggesting that the\nemission is likely due to [Si I] line not [Fe II] line as in shocked material.\nThe structure of the optically-invisible western area of Cas A is clearly seen\nfor the first time. The area is filled with many Quasi-Stationary Flocculi\n(QSFs) and fragments of the disrupted ejecta shell. We suggest that the\nanomalous radio properties in this area could be due to the increased number of\nsuch dense clumps. We identified 309 knots in the deep [Fe II]+[Si I] image and\nclassified them into QSFs and fast-moving knots (FMKs). The total H+He mass of\nQSFs is ~0.23 Msun, implying that the mass fraction of dense clumps in the\nprogenitor's red-supergiant wind is 4--13%. The spatial distribution of QSFs\nsuggests that there had been a highly asymmetric mass loss $10^4$--$10^5$ yr\nbefore the SN explosion. The mass of the [Fe II] line-emitting, shocked dense\nFe ejecta is ~3x$10^{-5}$ Msun. The comparison with the ionic S-line dominated\nHubble Space Telescope WFC3/IR image suggests that the outermost FMKs in the\nsoutheastern area are Fe-rich.", "positive": "Dense and Warm Molecular Gas and Warm Dust in Nearby Galaxies: We performed 12CO(1-0), 13CO(1-0), and HCN(1-0) single-dish observations\n(beam size ~14\"-18\") toward nearby starburst and non-starburst galaxies using\nthe Nobeyama 45 m telescope. The 13CO(1-0) and HCN(1-0) emissions were detected\nfrom all the seven starburst galaxies, with the intensities of both lines being\nsimilar (i.e., the ratios are around unity). On the other hand, for case of the\nnon-starburst galaxies, the 13CO(1-0) emission was detected from all three\ngalaxies, while the HCN(1-0) emission was weakly or not detected in past\nobservations. This result indicates that the HCN/13CO intensity ratios are\nsignificantly larger (~1.15+-0.32) in the starburst galaxy samples than the\nnon-starburst galaxy samples (<0.31+-0.14). The large-velocity-gradient model\nsuggests that the molecular gas in the starburst galaxies have warmer and\ndenser conditions than that in the non-starburst galaxies, and the\nphoton-dominated-region model suggests that the denser molecular gas is\nirradiated by stronger interstellar radiation field in the starburst galaxies\nthan that in the non-starburst galaxies. In addition, HCN/13CO in our sample\ngalaxies exhibit strong correlations with the IRAS 25 micron flux ratios. It is\na well established fact that there exists a strong correlation between dense\nmolecular gas and star formation activities, but our results suggest that\nmolecular gas temperature is also an important parameter." }, { "anchor": "IR-correlated 31 GHz radio emission from Orion East: Lynds dark cloud LDN1622 represents one of the best examples of anomalous\ndust emission, possibly originating from small spinning dust grains. We present\nCosmic Background Imager (CBI) 31 GHz data of LDN1621, a diffuse dark cloud to\nthe north of LDN1622 in a region known as Orion East. A broken ring with\ndiameter g\\approx 20 arcmin of diffuse emission is detected at 31 GHz, at\n\\approx 20-30 mJy beam$^{-1}$ with an angular resolution of \\approx 5 arcmin.\nThe ring-like structure is highly correlated with Far Infra-Red emission at\n$12-100 \\mu$m with correlation coefficients of r \\approx 0.7-0.8, significant\nat $\\sim10\\sigma$. Multi-frequency data are used to place constraints on other\ncomponents of emission that could be contributing to the 31 GHz flux. An\nanalysis of the GB6 survey maps at 4.85 GHz yields a $3\\sigma$ upper limit on\nfree-free emission of 7.2 mJy beam$^{-1}$ ($\\la 30 per cent of the observed\nflux) at the CBI resolution. The bulk of the 31 GHz flux therefore appears to\nbe mostly due to dust radiation. Aperture photometry, at an angular resolution\nof 13 arcmin and with an aperture of diameter 30 arcmin, allowed the use of\nIRAS maps and the {\\it WMAP} 5-year W-band map at 93.5 GHz. A single modified\nblackbody model was fitted to the data to estimate the contribution from\nthermal dust, which amounts to $\\sim$ 10 per cent at 31 GHz. In this model, an\nexcess of 1.52\\pm 0.66 Jy (2.3\\sigma) is seen at 31 GHz. Future high frequency\n$\\sim$ 100-1000 GHz data, such as those from the {\\it Planck} satellite, are\nrequired to accurately determine the thermal dust contribution at 31 GHz.\nCorrelations with the IRAS $100 \\mu$m gave a coupling coefficient of\n$18.1\\pm4.4 \\mu$K (MJy/sr)$^{-1}$, consistent with the values found for\nLDN1622.", "positive": "Milky Way demographics with the VVV survey. I. The 84-million star\n colour-magnitude diagram of the Galactic bulge: The Milky Way (MW) bulge is a fundamental Galactic component for\nunderstanding the formation and evolution of galaxies, in particular our own.\nThe ESO Public Survey VISTA Variables in the Via Lactea is a deep near-IR\nsurvey mapping the Galactic bulge and southern plane. Data taken during 2010-11\ncovered 315 deg2 in the bulge area in the JHKs bands. We used VVV data for the\nwhole bulge area as a single and homogeneous data set to build for the first\ntime a single colour-magnitude diagram (CMD) for the entire Galactic bulge.\nPhotometric data in the JHKs bands were combined to produce a single and huge\ndata set containing 173.1M+ sources in the three bands. Selecting only the data\npoints flagged as stellar, the total number of sources is 84.0M+. We built the\nlargest CMDs published up to date, containing 173.1+ million sources for all\ndata points, and more than 84.0 million sources accounting for the stellar\nsources only. The CMD has a complex shape, mostly owing to the complexity of\nthe stellar population and the effects of extinction and reddening towards the\nGalactic centre. The red clump (RC) giants are seen double in magnitude at b ~\n-8-10 deg, while in the inner part (b ~ 3deg) they appear to be spreading in\ncolour, or even splitting into a secondary peak. The analysis of the outermost\nbulge area reveals a well-defined sequence of late K and M dwarfs, seen at\n(J-Ks) ~ 0.7-0.9 mag and Ks~14 mag. The interpretation of the CMD yields\nimportant information about the MW bulge, showing the fingerprint of its\nstructure and content. We report a well-defined red dwarf sequence in the\noutermost bulge, which is important for the planetary transit searches of VVV.\nThe double RC in magnitude seen in the outer bulge is the signature of the\nX-shaped MW bulge, while the spreading of the RC in colour are caused by\nreddening effects." }, { "anchor": "Observations of the Icy Universe: Freeze-out of the gas phase elements onto cold grains in dense interstellar\nand circumstellar media builds up ice mantles consisting of molecules that are\nmostly formed in situ (H2O, NH3, CO2, CO, CH3OH, and more). This review\nsummarizes the detected infrared spectroscopic ice features and compares the\nabundances across Galactic, extragalactic, and solar system environments. A\ntremendous amount of information is contained in the ice band profiles.\nLaboratory experiments play a critical role in the analysis of the\nobservations. Strong evidence is found for distinct ice formation stages,\nseparated by CO freeze out at high densities. The ice bands have proven to be\nexcellent probes of the thermal history of their environment. The evidence for\nthe long-held idea that processing of ices by energetic photons and cosmic rays\nproduces complex molecules is weak. Recent state of the art observations show\npromise for much progress in this area with planned infrared facilities.", "positive": "Testing the Galactic Centre potential with S-stars: Two groups of astronomers used the large telescopes Keck and VLT for decades\nto observe trajectories of bright stars near the Galactic Centre. Based on\nresults of their observations the astronomers concluded that trajectories of\nthe stars are roughly elliptical and foci of the orbits are approximately\ncoincide with the Galactic Centre position. In a last few years a\nself-gravitating dark matter core--halo distribution was suggested by Ruffini,\nArguelles, Rueda (RAR) and this model was actively used in consequent studies.\nIn particular, recently it has been claimed that the RAR-model provides a\nbetter fit of trajectories of bright stars in comparison to the conventional\nmodel with a supermassive black hole. The dark matter distribution with a dense\ncore having a constant density as it was suggested in the RAR-model leaves\ntrajectories of stars elliptical like in Kepler's two-body problem. However, in\nthis case not the foci of the ellipses coincide with the Galactic Center but\ntheir centers while the orbital periods do not depend on semi-major axes. These\nproperties are not consistent with the observational data for trajectories of\nbright stars." }, { "anchor": "The Massive Stellar Population in the Young Association LH 95 in the LMC: We present a spectroscopic study of the most massive stars in the young (4\nMyr old) stellar cluster LH 95 in the Large Magellanic Cloud. This analysis\nallows us to complete the census of the stellar population of the system,\npreviously investigated by us down to 0.4 solar masses with deep HST Advanced\nCamera for Surveys photometry. We perform spectral classification of the five\nstars in our sample, based on high resolution optical spectroscopy obtained\nwith 2.2m MPG/ESO FEROS. We use complementary ground-based photometry,\npreviously performed by us, to place these stars in the Hertzsprung-Russel\ndiagram. We derive their masses and ages by interpolation from evolutionary\nmodels. The average ages and age spread of the most massive stars are found to\nbe in general comparable with those previously derived for the cluster from its\nlow mass PMS stars. We use the masses of the 5 sample stars to extend to the\nhigh-mass end the stellar initial mass function of LH 95 previously established\nby us. We find that the initial mass function follows a Salpeter relation down\nto the intermediate-mass regime at 2 Msun. The second most massive star in LH\n95 shows broad Balmer line emission and infrared excess, which are compatible\nwith a classical Be star. The existence of such a star in the system adds a\nconstrain to the age of the cluster, which is well covered by our age and age\nspread determinations. The most massive star, a 60-70 Msun O2 giant is found to\nbe younger (<1 Myr) than the rest of the population. Its mass in relation to\nthe total mass of the system does not follow the empirical relation of the\nmaximum stellar mass versus the hosting cluster mass, making LH 95 an exception\nto the average trend.", "positive": "Photoionization models of Planetary Nebulae: The understanding of astronomical nebulae is based on observational data\n(images, spectra, 3D data-cubes) and theoretical models. In this review, I\npresent my very biased view on photoionization modeling of planetary nebulae,\nfocusing on 1D multi-component models, on 3D models and on big database of\nmodels." }, { "anchor": "The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*.\n I. Detection of a rich population of dusty objects in the IRS 13 cluster: A detailed analysis of the Nuclear Stellar Cluster (NSC) concedes not only\nthe existence of the Scluster with its fast-moving stars and the supermassive\nblack hole (SMBH) Sgr A*. It also reveals an embedded region of gas and dust\nwith an exceptionally high stellar density called IRS 13. The IRS 13 cluster\ncan be divided into the northern and the eastern counterparts, called IRS 13N\nand IRS 13E, respectively. This work will focus on both regions and study their\nmost prominent members using rich infrared and radio/submm data baselines.\nApplying a multiwavelength analysis enables us to determine a comprehensive\nphotometric footprint of the investigated cluster sample. Using the\nraytracing-based radiative transfer model HYPERION, the spectral energy\ndistribution of the IRS 13 members suggests a stellar nature of the dusty\nsources. These putative Young Stellar Objects (YSOs) have a comparable\nspectroscopic identification to the D and G sources in or near the S cluster.\nFurthermore, we report the existence of a population of dusty sources in IRS 13\nthat can be mostly identified in the H-, K-, and Lband. Together with the\nobjects reported in literature, we propose that this population is the outcome\nof a recent star formation process. Furthermore, we report that these\npresumably young objects are arranged in a disk structure. Although it cannot\nbe excluded that the intrinsic arrangement of IRS 13 does show a disk\nstructure, we find indications that the investigated cluster sample might be\nrelated to the counterclockwise disk.", "positive": "CLASH: Accurate Photometric Redshifts with 14 HST bands in Massive\n Galaxy Cluster Cores: We present accurate photometric redshifts for galaxies observed by the\nCluster Lensing and Supernova survey with Hubble (CLASH). CLASH observed 25\nmassive galaxy cluster cores with the Hubble Space Telescope in 16 filters\nspanning 0.2 - 1.7 $\\mu$m. Photometry in such crowded fields is challenging.\nCompared to our previously released catalogs, we make several improvements to\nthe photometry, including smaller apertures, ICL subtraction, PSF matching, and\nempirically measured uncertainties. We further improve the Bayesian Photometric\nRedshift (BPZ) estimates by adding a redder elliptical template and by\ninflating the photometric uncertainties of the brightest galaxies. The\nresulting photometric redshift accuracies are dz/(1+z) $\\sim$ 0.8\\%, 1.0\\%, and\n2.0\\% for galaxies with I-band F814W AB magnitudes $<$ 18, 20, and 23,\nrespectively. These results are consistent with our expectations. They improve\non our previously reported accuracies by a factor of 4 at the bright end and a\nfactor of 2 at the faint end. Our new catalog includes 1257 spectroscopic\nredshifts, including 382 confirmed cluster members. We also provide stellar\nmass estimates. Finally, we include lensing magnification estimates of\nbackground galaxies based on our public lens models. Our new catalog of all 25\nCLASH clusters is available via MAST. The analysis techniques developed here\nwill be useful in other surveys of crowded fields, including the Frontier\nFields and surveys carried out with J-PAS and JWST." }, { "anchor": "Collapse and fragmentation of molecular clouds under pressure: Recent analytical and numerical models show that AGN outflows and jets create\nISM pressure in the host galaxy that is several orders of magnitude larger than\nin quiescent systems. This pressure increase can confine and compress molecular\ngas, thus accelerating star formation. In this paper, we model the effects of\nincreased ambient ISM pressure on spherically symmetric turbulent molecular\nclouds. We find that large external pressure confines the cloud and drives a\nshockwave into it, which, together with instabilities behind the shock front,\nsignificantly accelerates the fragmentation rate. The compressed clouds\ntherefore convert a larger fraction of their mass into stars over the cloud\nlifetime, and produce clusters that are initially more compact. Neither cloud\nrotation nor shear against the ISM affect this result significantly, unless the\nshear velocity is higher than the sound speed in the confining ISM. We conclude\nthat external pressure is an important element in the star formation process,\nprovided that it dominates over the internal pressure of the cloud.", "positive": "Tracking the Local Group Dynamics by Extended Gravity: The Local Group (LG) of galaxies, modeled as a two body problem, is sensitive\nto cosmological contributions like those related to the presence of a\ncosmological constant $\\Lambda$ into dynamics. Here we study the LG dynamics in\nthe context of Extended Theories of Gravity like $f(R)$ gravity considered as\ndark energy and dark matter contributions. In the first approach, we perturb\nthe dark energy effect considering a Yukawa-like interaction that naturally\nemerges from $f(R)$ gravity in the weak field limit. We assume the mass of LG\nfrom simulations and, from this, derive constraints on the Yukawa couplings:\n$\\alpha < 0.581$ and $m_{grav} < 5.095 \\cdot 10^{-26} \\, eV/c^2$. In the second\npart, considering a minimal extension of General Relativity, i.e. $f(R) \\sim\nR^{1+\\epsilon}$, with $|\\epsilon|\\ll 1$, we investigate the possibility that it\nreplaces dark matter as a MOND-like theory. We find that there is a value of\nthe parameter $\\beta$ (derived starting from $\\epsilon$) which gives a minimal\nvalue for the LG mass. Moreover, this particular potential allows to calculate\nthe ratio of dark matter and baryonic matter for the LG to be. We show that\nthis ratio could falsify MOND-like theories." }, { "anchor": "On the population of remnant FRII radio galaxies and implications for\n radio source dynamics: The purpose of this work is two-fold: (1) to quantify the occurrence of\nultra-steep spectrum remnant FRII radio galaxies in a 74 MHz flux limited\nsample, and (2) perform Monte-Carlo simulations of the population of active and\nremnant FRII radio galaxies to confront models of remnant lobe evolution, and\nprovide guidance for further investigation of remnant radio galaxies. We find\nthat fewer than 2$\\%$ of FRII radio galaxies with S$_{ \\rm74~MHz} > 1.5$ Jy are\ncandidate ultra-steep spectrum remnants, where we define ultra-steep spectrum\nas $\\alpha_{\\rm 74~MHz}^{\\rm 1400~MHz} > 1.2$. Our Monte-Carlo simulations\ndemonstrate that models involving Sedov-like expansion in the remnant phase,\nresulting in rapid adiabatic energy losses, are consistent with this upper\nlimit, and predict the existence of nearly twice as many remnants with normal\n(not ultra-steep) spectra in the observed frequency range as there are\nultra-steep spectrum remnants. This model also predicts an ultra-steep remnant\nfraction approaching 10$\\%$ at redshifts $z < 0.5$. Importantly, this model\nimplies the lobes remain over-pressured with respect to the ambient medium well\nafter their active lifetime, in contrast with existing observational evidence\nthat many FRII radio galaxy lobes reach pressure equilibrium with the external\nmedium whilst still in the active phase. The predicted age distribution of\nremnants is a steeply decreasing function of age. In other words young remnants\nare expected to be much more common than old remnants in flux limited samples.\nFor this reason, incorporating higher frequency data $\\gtrsim 5$ GHz will be of\ngreat benefit to future studies of the remnant population.", "positive": "Radio core dominance of Fermi-LAT selected AGNs: Aims. We present a sample of 4388 AGNs with available radio core-dominance\nparameters defined as the ratio of the core flux densities to extended ones,\nnamely, R = Score/Sext., which includes 630 Fermi-detected AGNs respect to the\ncatalog of 4FGL, the fourth Fermi Large Area Telescope source catalog, and the\nrest of them are non-Fermi-detected AGNs. In our sample, 584 blazars are\nFermi-detected and 1310 are not, and also consists of other subclasses such as\nSeyfert, Fanaroff-Riley I/II and normal galaxies. We investigate various\ndifferent properties between Fermi-detected AGNs and non-Fermi-detected ones by\nusing the core-dominance parameters as the previous study has shown that R is a\ngood indication of beaming effect. Methods. We then calculate the radio\nspectral indices for whole sample and adopt {\\gamma}-ray photon indices for\nFermi AGNs from 4FGL catalog for discussing their different performances on\ndifferent subclasses, and obtain the relation between core-dominance parameters\nand radio spectral indices for both Fermi and non-Fermi sources according to\nthe two components model on radio band, which are consistent with our previous\nstudy. Results. We found that the core-dominance parameters and radio spectral\nindices are quite different for different subclasses of AGNs, not only for\nFermi sources but also non-Fermi sources, particularly, R for the former ones\nis averagely higher than later ones. We also adopt the same relation on\ncore-dominance parameters and {\\gamma}-ray photon indices for Fermi sources by\ntaking the same assumption with two components model on {\\gamma}-ray band, and\nobtain the fitting results indicating that the {\\gamma}-ray emissions of Fermi\nblazars are mainly from the core component, which is perhaps associated with\nthe beaming effect. Therefore, Fermi blazars are beamed." }, { "anchor": "Formation of massive seed black holes via collisions and accretion: Models aiming to explain the formation of massive black hole seeds, and in\nparticular the direct collapse scenario, face substantial difficulties. These\nare rooted in rather ad hoc and fine-tuned initial conditions, such as the\nsimultaneous requirements of extremely low metallicities and strong radiation\nbackgrounds. Here we explore a modification of such scenarios where a massive\nprimordial star cluster is initially produced. Subsequent stellar collisions\ngive rise to the formation of massive (10^4 - 10^5 solar mass) objects. Our\ncalculations demonstrate that the interplay between stellar dynamics, gas\naccretion and protostellar evolution is particularly relevant. Gas accretion\nonto the protostars enhances their radii, resulting in an enhanced collisional\ncross section. We show that the fraction of collisions can increase from 0.1-1%\nof the initial population to about 10% when compared to gas-free models or\nmodels of protostellar clusters in the local Universe. We conclude that very\nmassive objects can form in spite of initial fragmentation, making the first\nmassive protostellar clusters viable candidate birth places for observed\nsupermassive black holes.", "positive": "Galactic Constraints on Supernova Progenitor Models: We undertake a statistical analysis of the radial abundance distributions in\nthe Galactic disk within a theoretical framework for Galactic chemical\nevolution which incorporates the influence of spiral arms. 1) The mean mass of\noxygen ejected per core-collapse SNe (CC SNe) event (which are concentrated\nwithin spiral arms) is $\\sim$0.27 M$_{\\odot}$; 2) the mean mass of iron ejected\nby `tardy' Type Ia SNe (SNeIa; progenitors of whom are older/longer-lived stars\nwith ages $\\simgt$100 Myr and up to several Gyr, which do not concentrate\nwithin spiral arms) is $\\sim$0.58 M$_{\\odot}$; 3) the upper mass of iron\nejected by prompt SNeIa (SNe whose progenitors are younger/shorter-lived stars\nwith ages $\\simlt$100 Myr, which are concentrated within spiral arms) is\n$\\leq$0.23 M$_{\\odot}$ per event; 4) the corresponding mean mass of iron\nproduced by CC SNe is $\\leq$0.04 M$_{\\odot}$ per event; (v) short-lived SNe\n(core-collapse or prompt SNeIa) supply $\\sim$85% of the Galactic disk's iron.\n The inferred low mean mass of oxygen ejected per CC SNe event implies a low\nupper mass limit for the corresponding progenitors of $\\sim$23 M$_{\\odot}$,\notherwise the Galactic disk would be overabundant in oxygen.\n The low mean mass of iron ejected by prompt SNeIa, relative to the mass\nproduced by tardy SNeIa ($\\sim$2.5 times lower), prejudices the idea that both\nsub-populations of SNeIa have the same physical nature. We suggest that,\nperhaps, prompt SNeIa are more akin to CC SNe, and discuss the implications of\nsuch a suggestion." }, { "anchor": "A deep dive into the Type II Globular Cluster NGC 1851: About one-fifth of the Galactic globular clusters (GCs), dubbed Type II GCs,\nhost distinct stellar populations with different heavy elements abundances. NGC\n1851 is one of the most studied Type II GCs, surrounded by several\ncontroversies regarding the spatial distribution of its populations and the\npresence of star-to-star [Fe/H], C+N+O, and age differences. This paper\nprovides a detailed characterization of its stellar populations through Hubble\nSpace Telescope (HST), ground-based, and Gaia photometry. We identified two\ndistinct populations with different abundances of s-process elements along the\nred-giant branch (RGB) and the sub-giant branch (SGB) and detected two\nsub-populations among both s-poor (canonical) and s-rich (anomalous) stars. To\nconstrain the chemical composition of these stellar populations, we compared\nobserved and simulated colors of stars with different abundances of He, C, N,\nand O. It results that the anomalous population has a higher CNO overall\nabundance compared to the canonical population and that both host stars with\ndifferent light-element abundances. No significant differences in radial\nsegregation between canonical and anomalous stars are detected, while we find\nthat among their sub-populations, the two most chemical extremes are more\ncentrally concentrated. Anomalous and canonical stars show different 2D spatial\ndistributions outside ~3 arcmin, with the latter developing an elliptical shape\nand a stellar overdensity in the northeast direction. We confirm the presence\nof a stellar halo up to ~80 arcmin with Gaia photometry, tagging 14 and five of\nits stars as canonical and anomalous, respectively, finding a lack of the\nlatter in the south/southeast field.", "positive": "Comparing Various Approaches to Simulating the Formation of Shell\n Galaxies: The model of a radial minor merger proposed by Quinn (1984), which\nsuccessfully reproduces the observed regular shell systems in shell galaxies,\nis ideal for a test-particle simulation. We compare such a simulation with a\nself-consistent one. They agree very well in positions of the first generation\nof shells but potentially important effects -- dynamical friction and gradual\ndecay of the dwarf galaxy -- are not present in the test-particle model,\ntherefore we look for a proper way to include them." }, { "anchor": "Magnetic Fields in the Central Molecular Zone Influenced by Feedback and\n Weakly Correlated with Star Formation: Magnetic fields of molecular clouds in the Central Molecular Zone (CMZ) have\nbeen relatively underobserved at sub-parsec resolution. Here we report\nJCMT/POL2 observations of polarized dust emission in the CMZ, which reveal\nmagnetic field structures in dense gas at ~0.5 pc resolution. The eleven\nmolecular clouds in our sample including two in the western part of the CMZ\n(Sgr C and a far-side cloud candidate), four around the Galactic longitude 0\n(the 50 km s-1 cloud, CO0.02-0.02, the `Stone' and the `Sticks & Straw' among\nthe Three Little Pigs), and five along the Dust Ridge (G0.253+0.016, clouds b,\nc, d, and e/f), for each of which we estimate the magnetic field strength using\nthe angular dispersion function method. The morphologies of magnetic fields in\nthe clouds suggest potential imprints of feedback from expanding H II regions\nand young massive star clusters. A moderate correlation between the total viral\nparameter versus the star formation rate and the dense gas fraction of the\nclouds is found. A weak correlation between the mass-to-flux ratio and the star\nformation rate, and a weak anti-correlation between the magnetic field and the\ndense gas fraction are also found. Comparisons between magnetic fields and\nother dynamic components in clouds suggest a more dominant role of self-gravity\nand turbulence in determining the dynamical states of the clouds and affecting\nstar formation at the studied scales.", "positive": "The SAMI Galaxy Survey: impact of black hole activity on galaxy\n spin-filament alignments: The activity of central supermassive black holes might affect the alignment\nof galaxy spin axes with respect to the closest cosmic filaments. We exploit\nthe SAMI Galaxy Survey to study possible relations between black hole activity\nand the spin-filament alignments of stars and ionised gas separately. To\nexplore the impact of instantaneous black hole activity, active galaxies are\nselected according to emission-line diagnostics. Central stellar velocity\ndispersion ($\\sigma_c$) is used as a proxy for black hole mass and its\nintegrated activity. We find evidence for the gas spin-filament alignments to\nbe influenced by AGN, with Seyfert galaxies showing a stronger perpendicular\nalignment at fixed bulge mass with respect to galaxies where ionisation is\nconsequence of low-ionizaition nuclear emission-line regions (LINERs) or old\nstellar populations (retired galaxies). On the other hand, the greater\nperpendicular tendency for the stellar spin-filament alignments of high-bulge\nmass galaxies is dominated by retired galaxies. Stellar alignments show a\nstronger correlation with $\\sigma_c$ compared to the gas alignments. We confirm\nthat bulge mass ($M_{bulge}$) is the primary parameter of correlation for both\nstellar and gas spin-filament alignments (with no residual dependency left for\n$\\sigma_c$), while $\\sigma_c$ is the most important property for secular star\nformation quenching (with no residual dependency left for $M_{bulge}$). These\nfindings indicate that $M_{bulge}$ and $\\sigma_c$ are the most predictive\nparameters of two different galaxy evolution processes, suggesting mergers\ntrigger spin-filament alignment flips and integrated black hole activity drives\nstar formation quenching." }, { "anchor": "Temperature-based metallicity measurements at z=0.8: direct calibration\n of strong-line diagnostics at intermediate redshift: We present the first direct calibration of strong-line metallicity\ndiagnostics at significant cosmological distances using a sample at z=0.8 drawn\nfrom the DEEP2 Galaxy Redshift Survey. Oxygen and neon abundances are derived\nfrom measurements of electron temperature and density. We directly compare\nvarious commonly used relations between gas-phase metallicity and strong line\nratios of O, Ne, and H at z=0.8 and z=0. There is no evolution with redshift at\nhigh precision ($\\Delta \\log{\\mathrm{O/H}} = -0.01\\pm0.03$, $\\Delta\n\\log{\\mathrm{Ne/O}} = 0.01 \\pm 0.01$). O, Ne, and H line ratios follow the same\nlocus at z=0.8 as at z=0 with $\\lesssim$0.02 dex evolution and low scatter\n($\\lesssim$0.04 dex). This suggests little or no evolution in physical\nconditions of HII regions at fixed oxygen abundance, in contrast to models\nwhich invoke more extreme properties at high redshifts. We speculate that\noffsets observed in the [N II]/H$\\alpha$ versus [O III]/H$\\beta$ diagram at\nhigh redshift are therefore due to [NII] emission, likely as a result of\nrelatively high N/O abundance. If this is indeed the case, then nitrogen-based\nmetallicity diagnostics suffer from systematic errors at high redshift. Our\nfindings indicate that locally calibrated abundance diagnostics based on\nalpha-capture elements can be reliably applied at z$\\simeq$1 and possibly at\nmuch higher redshifts. This constitutes the first firm basis for the widespread\nuse of empirical calibrations in high redshift metallicity studies.", "positive": "Constraining the Anomalous Microwave Emission Mechanism in the S140 Star\n Forming Region with Spectroscopic Observations Between 4 and 8 GHz at the\n Green Bank Telescope: Anomalous microwave emission (AME) is a category of Galactic signals that\ncannot be explained by synchrotron radiation, thermal dust emission, or\noptically thin free-free radiation. Spinning dust is one variety of AME that\ncould be partially polarized and therefore relevant for ongoing and future\ncosmic microwave background polarization studies. The Planck satellite mission\nidentified candidate AME regions in approximately $1^\\circ$ patches that were\nfound to have spectra generally consistent with spinning dust grain models. The\nspectra for one of these regions, G107.2+5.2, was also consistent with\noptically thick free-free emission because of a lack of measurements between 2\nand 20 GHz. Follow-up observations were needed. Therefore, we used the C-band\nreceiver (4 to 8 GHz) and the VEGAS spectrometer at the Green Bank Telescope to\nconstrain the AME mechanism. For the study described in this paper, we produced\nthree band averaged maps at 4.575, 5.625, and 6.125 GHz and used aperture\nphotometry to measure the spectral flux density in the region relative to the\nbackground. We found if the spinning dust description is correct, then the\nspinning dust signal peaks at $30.9 \\pm 1.4$ GHz, and it explains the excess\nemission. The morphology and spectrum together suggest the spinning dust grains\nare concentrated near S140, which is a star forming region inside our chosen\nphotometry aperture. If the AME is sourced by optically thick free-free\nradiation, then the region would have to contain HII with an emission measure\nof $5.27^{+2.5}_{-1.5}\\times 10^8$ $\\rm{cm^{-6}\\,pc}$ and a physical extent of\n$1.01^{+0.21}_{-0.20} \\times 10^{-2}\\,\\rm{pc}$. This result suggests the HII\nwould have to be ultra or hyper compact to remain an AME candidate." }, { "anchor": "From Images to Features: Unbiased Morphology Classification via\n Variational Auto-Encoders and Domain Adaptation: We present a novel approach for the dimensionality reduction of galaxy images\nby leveraging a combination of variational auto-encoders (VAE) and domain\nadaptation (DA). We demonstrate the effectiveness of this approach using a\nsample of low redshift galaxies with detailed morphological type labels from\nthe Galaxy-Zoo DECaLS project. We show that 40-dimensional latent variables can\neffectively reproduce most morphological features in galaxy images. To further\nvalidate the effectiveness of our approach, we utilised a classical random\nforest (RF) classifier on the 40-dimensional latent variables to make detailed\nmorphology feature classifications. This approach performs similarly to a\ndirect neural network application on galaxy images. We further enhance our\nmodel by tuning the VAE network via DA using galaxies in the overlapping\nfootprint of DECaLS and BASS+MzLS, enabling the unbiased application of our\nmodel to galaxy images in both surveys. We observed that DA led to even better\nmorphological feature extraction and classification performance. Overall, this\ncombination of VAE and DA can be applied to achieve image dimensionality\nreduction, defect image identification, and morphology classification in large\noptical surveys.", "positive": "Determination of Cycle Length of Quasi-Periodic Signals. Application to\n Semiregular Variables: We review methods for determination of \"quasi-periods\" (or \"cycle length\") of\nsignals of low coherence. Such type of variability was called \"cyclic\" for\nsemi-regular red variables, or \"quasi-periodic oscillations\" (QPO) for fast\nvariability in cataclysmic variables and related objects. Methods are\nillustrated by application to AF Cygni." }, { "anchor": "Detecting Globular Cluster Tidal Extensions with Bayesian Inference: I.\n Analysis of $\u03c9$ Centauri with Gaia EDR3: The peripheral regions of globular clusters (GCs) are extremely challenging\nto study due to their low surface brightness nature and the dominance of Milky\nWay contaminant populations along their sightlines. We have developed a\nprobabilistic approach to this problem through utilising a mixture model in\nspatial and proper motion space which separately models the cluster,\nextra-tidal and contaminant stellar populations. We demonstrate the efficacy of\nour method through application to Gaia EDR3 photometry and astrometry in the\ndirection of NGC 5139 ($\\omega$ Cen), a highly challenging target on account of\nits Galactic latitude ($b\\approx 15^{\\circ}$) and low proper motion contrast\nwith the surrounding field. We recover the spectacular tidal extensions,\nspanning the $10^{\\circ}$ on the sky explored here, seen in earlier work and\nquantify the star count profile and ellipticity of the system out to a\ncluster-centric radius of $4^{\\circ}$. We show that both RR Lyrae and blue\nhorizontal branch stars consistent with belonging to $\\omega$ Cen are found in\nthe tidal tails, and calculate that these extensions contain at least $\\approx\n0.1$ per cent of the total stellar mass in the system. Our high probability\nmembers provide prime targets for future spectroscopic studies of $\\omega$ Cen\nout to unprecedented radii.", "positive": "H-alpha Images of Ultra-Flat Edge-On Spiral Galaxies: We present the H$\\alpha$ images of ultra-flat (UF) spiral galaxies seen\npractically edge-on. The galaxies have the angular diameter in the $B$ band $a>\n1.9^{\\prime}$ and the apparent axial ratio $(a/b) >10$. We found that their\nH$\\alpha$ images look, on average, almost two times thinner than those in the\nred continuum. The star-formation rate in the studied objects, determined from\nthe H$\\alpha$ flux, is in good agreement with that calculated from the $FUV$\nflux from the GALEX survey if we use the modified Verheijen and Sancisi formula\ntaking into account the internal extinction in the UF galaxies. The logarithm\nof the specific star-formation rate in the UF galaxies shows a small scatter,\n$0.19$, with a smooth decrease from $-10.4$ for dwarf spirals to $-10.7$ for\nmassive ones. The relative amount of the hydrogen mass in UF disks varies from\nabout 50\\% in dwarf disks to about 8\\% in massive ones. Structural distortions\nare less common in the UF galaxies (about 16\\%) than those in thick (less\nisolated) disks of edge-on spiral galaxies. On the cosmic time scale, 13.7 Gyr,\nlarge spiral disks are more efficient \"engines\" for gas processing into stars\nthan dwarf spirals." }, { "anchor": "Mapping the core mass function to the initial mass function: It has been shown that fragmentation within self-gravitating, turbulent\nmolecular clouds (\"turbulent fragmentation\") can naturally explain the observed\nproperties of protostellar cores, including the core mass function (CMF). Here,\nwe extend recently-developed analytic models for turbulent fragmentation to\nfollow the time-dependent hierarchical fragmentation of self-gravitating cores,\nuntil they reach effectively infinite density (and form stars). We show that\nturbulent fragmentation robustly predicts two key features of the IMF. First, a\nhigh-mass power-law scaling very close to the Salpeter slope, which is a\ngeneric consequence of the scale-free nature of turbulence and self-gravity. We\npredict the IMF slope (-2.3) is slightly steeper then the CMF slope (-2.1),\nowing to the slower collapse and easier fragmentation of large cores. Second, a\nturnover mass, which is set by a combination of the CMF turnover mass (a couple\nsolar masses, determined by the `sonic scale' of galactic turbulence, and so\nweakly dependent on galaxy properties), and the equation of state (EOS). A\n\"soft\" EOS with polytropic index $\\gamma<1.0$ predicts that the IMF slope\nbecomes \"shallow\" below the sonic scale, but fails to produce the full turnover\nobserved. An EOS which becomes \"stiff\" at sufficiently low surface densities\n$\\Sigma_{\\rm gas} \\sim 5000\\,M_{\\odot}\\,{\\rm pc^{-2}}$, and/or models where\neach collapsing core is able to heat and effectively stiffen the EOS of a\nmodest mass ($\\sim 0.02\\,M_{\\odot}$) of surrounding gas, are able to reproduce\nthe observed turnover. Such features are likely a consequence of more detailed\nchemistry and radiative feedback.", "positive": "Variable stars in Local Group Galaxies -- V. The fast and early\n evolution of the low-mass Eridanus II dSph galaxy: We present a detailed study of the variable star population of Eridanus II\n(Eri II), an ultra-faint dwarf galaxy that lies close to the Milky Way virial\nradius. We analyze multi-epoch $g,r,i$ ground-based data from Goodman and the\nDark Energy Camera, plus $F475W, F606W, F814W$ space data from the Advanced\nCamera for Surveys. We report the detection of 67 RR Lyrae (RRL) stars and 2\nAnomalous Cepheids, most of them new discoveries. With the RRL stars, we\nmeasure the distance modulus of Eri II, $\\mu_0=22.84\\pm 0.05$ mag\n(D$_{\\odot}=370\\pm9$ kpc) and derive a metallicity spread of 0.3 dex (0.2 dex\nintrinsic). The colour distribution of the horizontal branch (HB) and the\nperiod distribution of the RRL stars can be nicely reproduced by a combination\nof two stellar models of [Fe/H]=($-2.62$, $-2.14$). The overall low metallicity\nis consistent with the red giant branch bump location, 0.65 mag brighter than\nthe HB. These results are in agreement with previous spectroscopic studies. The\nmore metal-rich RRL and the RRab stars have greater central concentration than\nthe more metal-poor RRL and the RRc stars that are mainly located outside $\\sim\n1$ r$_{\\rm h}$. This is similar to what is found in larger dwarf galaxies such\nas Sculptor, and in agreement with an outside-in galaxy formation scenario.\nThis is remarkable in such a faint dwarf galaxy with an apparently single and\nextremely short ($<1$ Gyr) star formation burst. Finally, we have derived new\nand independent structural parameters for Eri II and its star cluster using our\nnew data that are in very good agreement with previous estimates." }, { "anchor": "The Mystery of the $\u03c3$-Bump -- A new Signature for Major Mergers in\n Early-type Galaxies?: The stellar velocity dispersion as a function of the galactocentric radius of\nan early-type galaxy can generally be well approximated by a power law $\\sigma\n\\propto r^{\\beta}$. However, some observed dispersion profiles show a deviation\nfrom this fit at intermediate radii, usually between one and three\n$R_{\\mathrm{eff}}$, where the velocity dispersion remains constant with radius,\nshowing a bump-like behavior, which we term the \"$\\sigma$-\"bump. To understand\nthe origin of this $\\sigma$-bump, we study a set of simulated early-type\ngalaxies formed in major mergers. We find the $\\sigma$-bump in all of our\nsimulated early-type galaxies, with the size and position of the bump slightly\nvarying from galaxy to galaxy, leading to the assumption that the bump is a\ncharacteristic of the major merger formation scenario. The feature can be seen\nboth in the intrinsic and projected stellar velocity dispersions. In contrast\nto shells that form during the merger event but evolve with time and finally\ndisappear, the $\\sigma$-bump stays nearly constant with radius and is a\npermanent feature that is preserved until the end of the simulation. The\n$\\sigma$-bump is not seen in the dark matter and gas components and we\ntherefore conclude that it is a purely stellar feature of merger remnants.", "positive": "Thermal instability of thin accretion disks in the presence of wind and\n toroidal magnetic field: We study the local thermal stability of thin accretion disks. We present a\nfull stability analysis in the presence of a magnetic field and more\nimportantly wind. For wind, we use a general model suitable for adequately\ndescribing several kinds of winds. First, we explicitly show that the magnetic\nfield, irrespective of the type of wind, has a stabilizing effect. This is also\ntrue when there is no wind. In this case, we confirm the other works already\npresented in the literature. However, our main objective is to investigate the\nlocal thermal stability of the disk in the presence of the wind. In this case,\ninterestingly, the response of disk is directly related to the type of wind. In\nother words, in some cases, the wind can stabilize the disk. On the other hand,\nin some cases, it can destabilize the disk. We found that in some thin disk\nmodels where the magnetic pressure cannot explain the stability of the disk by\nincluding a typical contribution for magnetic pressure, the wind can provide a\nviable explanation for the thermal stability." }, { "anchor": "MOONS Surveys of the Milky Way and its Satellites: The study of resolved stellar populations in the Milky Way and other Local\nGroup galaxies can provide us with a fossil record of their chemo-dynamical and\nstar-formation histories over timescales of many billions of years. In the\ngalactic components and stellar systems of the Milky Way and its satellites,\nindividual stars can be resolved. Therefore, they represent a unique laboratory\nin which to investigate the details of the processes behind the formation and\nevolution of the disc and dwarf/irregular galaxies. MOONS at the VLT represents\na unique combination of an efficient infrared multi-object spectrograph and a\nlarge-aperture 8-m-class telescope which will sample the cool stellar\npopulations of the dense central regions of the Milky Way and its satellites,\ndelivering accurate radial velocities, metallicities, and other chemical\nabundances for several millions of stars over its lifetime (see Cirasuolo et\nal., this issue). MOONS will observe up to 1000 targets across a 25-arcminute\nfield of view in the optical and near-infrared (0.6-1.8 micron) simultaneously.\nA high-resolution (R~19700) setting in the H band has been designed for the\naccurate determination of stellar abundances such as alpha, light, iron-peak\nand neutron-capture elements.", "positive": "Molecular gas heating in Arp 299: Understanding the heating and cooling mechanisms in nearby (Ultra) luminous\ninfrared galaxies can give us insight into the driving mechanisms in their more\ndistant counterparts. Molecular emission lines play a crucial role in cooling\nexcited gas, and recently, with Herschel Space Observatory we have been able to\nobserve the rich molecular spectrum. CO is the most abundant and one of the\nbrightest molecules in the Herschel wavelength range. CO transitions are\nobserved with Herschel, and together, these lines trace the excitation of CO.\nWe study Arp 299, a colliding galaxy group, with one component harboring an AGN\nand two more undergoing intense star formation. For Arp 299 A, we present PACS\nspectrometer observations of high-J CO lines up to J=20-19 and JCMT\nobservations of $^{13}$CO and HCN to discern between UV heating and alternative\nheating mechanisms. There is an immediately noticeable difference in the\nspectra of Arp 299 A and Arp 299 B+C, with source A having brighter high-J CO\ntransitions. This is reflected in their respective spectral energy line\ndistributions. We find that photon-dominated regions (PDRs) are unlikely to\nheat all the gas since a very extreme PDR is necessary to fit the high-J CO\nlines. In addition, this extreme PDR does not fit the HCN observations, and the\ndust spectral energy distribution shows that there is not enough hot dust to\nmatch the amount expected from such an extreme PDR. Therefore, we determine\nthat the high-J CO and HCN transitions are heated by an additional mechanism,\nnamely cosmic ray heating, mechanical heating, or X-ray heating. We find that\nmechanical heating, in combination with UV heating, is the only mechanism that\nfits all molecular transitions. We also constrain the molecular gas mass of Arp\n299 A to 3e9 Msun and find that we need 4% of the total heating to be\nmechanical heating, with the rest UV heating." }, { "anchor": "MHD Turbulence and Cosmic Ray Reacceleration in Galaxy Clusters: Cosmological MHD simulations of galaxy cluster formation show a significant\namplification of seed magnetic fields. We developed a novel method to decompose\ncluster magnetized turbulence into modes and showed that the fraction of the\nfast mode is fairly large, around 1/4 in terms of energy. This is larger than\nthat was estimated before, which implies that cluster turbulence interacts with\ncosmic rays rather efficiently. We propose a framework to deal with electron\nand proton reacceleration in galaxy clusters that includes feedback on\nturbulence. In particular, we establish a new upper limit on proton and\nelectron fluxes based on turbulence intensity. These findings, along with\ndetailed modeling of reacceleration, will help to reconcile the observed giant\nradio haloes and the unobserved diffuse gamma-ray emission from these clusters.", "positive": "ALMA reveals a warm and compact starburst around a heavily obscured\n supermassive black hole at z=4.75: We report ALMA Cycle 0 observations at 1.3mm of LESS J033229.4-275619\n(XID403), an Ultraluminous Infrared Galaxy at $z=4.75$ in the Chandra Deep\nField South hosting a Compton-thick QSO. The source is not resolved in our data\nat a resolution of $\\sim$0.75 arcsec, placing an upper-limit of 2.5 kpc to the\nhalf-light radius of the continuum emission from heated-dust. After\ndeconvolving for the beam size, however, we found a $\\sim3\\sigma$ indication of\nan intrinsic source size of $0.27\\pm0.08$ arcsec (Gaussian FWHM), which would\ncorrespond to $r_{half}\\sim0.9\\pm0.3$ kpc. We build the far-IR SED of XID403 by\ncombining datapoints from both ALMA and Herschel and fit it with a modified\nblackbody spectrum. For the first time, we measure the dust temperature\n$T_d=58.5\\pm5.3$ K in this system, which is comparable to what has been\nobserved in other high-z submillimeter galaxies. The measured star formation\nrate is SFR=$1020\\pm150$ $M_{\\odot}$ yr$^{-1}$, in agreement with previous\nestimates at lower S/N. Based on the measured SFR and source size, we constrain\nthe SFR surface density to be $\\Sigma_{SFR}>26\\;M_{\\odot}$yr$^{-1}$kpc$^{-2}$\n($\\sim200\\;M_{\\odot}$yr$^{-1}$kpc$^{-2}$ for $r_{half}\\sim0.9$ kpc). The\ncompactness of this starburst is comparable to what has been observed in other\nlocal and high-z starburst galaxies. If the gas mass measured from previous\n[CII] and CO(2-1) observations at low resolution is confined within the same\ndust region, assuming $r_{half}\\sim0.9\\pm0.3$ kpc, this would produce a column\ndensity of $N_H\\sim0.3-1.1\\times10^{24}$cm$^{-2}$ towards the central SMBH,\nsimilar to the column density of $\\approx1.4\\times10^{24}$cm$^{-2}$ measured\nfrom the X-rays. Then, in principle, if both gas and dust were confined on\nsub-kpc scales, this would be sufficient to produce the observed X-ray column\ndensity without any need of a pc-scale absorber [abridged]." }, { "anchor": "Compton-thick AGNs in the NuSTAR era. V: Joint NuSTAR and XMM-Newton\n spectral analysis of three \"soft-Gamma\" candidate CT-AGNs in the Swift-BAT\n 100-month catalog: We present the joint NuSTAR and XMM-Newton spectral analysis in the 0.6-70\nkeV band of three candidate Compton thick (CT-) AGN selected in the 100-month\nSwift-BAT catalog. These objects were previously classified as CT-AGNs based on\nlow quality Swift-XRT and Swift-BAT data, and had soft photon indices\n(Gamma>2.2) that suggested a potential overestimation of the line of sight\ncolumn density. Thanks to the high-quality NuSTAR and XMM-Newton data we were\nable to determine that in all three objects the photon index was significantly\noverestimated, and two out of three sources are reclassified from CT to Compton\nthin, confirming a previously observed trend, i.e., that a significant fraction\nof BAT-selected, candidate CT-AGNs with poor soft X-ray data are reclassified\nas Compton thin when the NuSTAR data are added to the fit. Finally, thanks to\nboth the good XMM-Newton spatial resolution and the high NuSTAR and XMM-Newton\nspectral quality, we found that the third object in our sample was associated\nto the wrong counterpart: the correct one, 2MASX J10331570+5252182, has\nredshift z=0.14036, which makes it one of the very few candidate CT-AGNs in the\n100-month BAT catalog detected at z>0.1, and a rare CT quasar.", "positive": "Investigating the amplitude and rotation of the phase spiral in the\n Milky Way outer disc: Context: With the data releases from the astrometric space mission Gaia, the\nexploration of the structure of the Milky Way has developed in unprecedented\ndetail and unveiled many previously unknown structures in the Galactic disc and\nhalo. One such feature is the phase spiral where the stars in the Galactic disc\nform a spiral density pattern in the $Z-V_Z$ plane. Aims: We aim to\ncharacterize the shape, rotation, amplitude, and metallicity of the phase\nspiral in the outer disc of the Milky Way. This will allow us to better\nunderstand which physical processes caused the phase spiral and can give\nfurther clues to the Milky Way's past and the events that contributed to its\ncurrent state. Methods: We use Gaia data release 3 (DR3) to get full position\nand velocity data on approximately 31.5 million stars, and metallicity for a\nsubset of them. We then compute the angular momenta of the stars and develop a\nmodel to characterise the phase spiral in terms of amplitude and rotation at\ndifferent locations in the disc. Results: We find that the rotation angle of\nthe phase spiral changes with Galactic azimuth and Galactocentric radius,\nmaking the phase spiral appear to rotate about $3^\\circ$ per degree in Galactic\nazimuth. Furthermore, we find that the phase spiral in the $2200 - 2400$ kpc km\ns$^{-1}$ range of angular momentum is particularly strong compared to the phase\nspiral that can be observed in the solar neighbourhood. The metallicity of the\nphase spiral appears to match that of the Milky Way disc field stars.\nConclusions: We created a new model capable of fitting several key parameters\nof the phase spiral. We have been able to determine the rotation rate of the\nphase spiral and found a peak in the phase spiral amplitude which manifests as\na very clear phase spiral when using only stars with similar angular momentum." }, { "anchor": "The Origin of the X-ray Emission from the High-velocity Cloud\n MS30.7-81.4-118: A soft X-ray enhancement has recently been reported toward the high-velocity\ncloud MS30.7-81.4-118 (MS30.7), a constituent of the Magellanic Stream. In\norder to investigate the origin of this enhancement, we have analyzed two\noverlapping XMM-Newton observations of this cloud. We find that the X-ray\nenhancement is $\\sim$6' or $\\sim$100 pc across, and is concentrated to the\nnorth and west of the densest part of the cloud. We modeled the X-ray\nenhancement with a variety of spectral models. A single-temperature equilibrium\nplasma model yields a temperature of $(3.69^{+0.47}_{-0.44}) \\times 10^6$ K and\na 0.4-2.0 keV luminosity of $7.9 \\times 10^{33}$ erg s$^{-1}$. However, this\nmodel underpredicts the on-enhancement emission around 1 keV, which may\nindicate the additional presence of hotter plasma ($T \\gtrsim 10^7$ K), or that\nrecombination emission is important. We examined several different physical\nmodels for the origin of the X-ray enhancement. We find that turbulent mixing\nof cold cloud material with hot ambient material, compression or shock heating\nof a hot ambient medium, and charge exchange reactions between cloud atoms and\nions in a hot ambient medium all lead to emission that is too faint. In\naddition, shock heating in a cool or warm medium leads to emission that is too\nsoft (for reasonable cloud speeds). We find that magnetic reconnection could\nplausibly power the observed X-ray emission, but resistive\nmagnetohydrodynamical simulations are needed to test this hypothesis. If\nmagnetic reconnection is responsible for the X-ray enhancement, the observed\nspectral properties could potentially constrain the magnetic field in the\nvicinity of the Magellanic Stream.", "positive": "Kinematics of M51-type interacting galaxies: We present a kinematic catalogue for 21 M51-type galaxies. It consists of\nradial velocity distributions observed with long slit spectroscopy along\ndifferent position angles, for both the main and satellite components. We\ndetect deviations from circular motion in most of the main galaxies of each\npair, due to the gravitational perturbation produced by the satellite galaxy.\nHowever some systems do not show significant distortions in their radial\nvelocity curves. We found some differences between the directions of the\nphotometric and kinematic major axes in the main galaxies with a bar subsystem.\nThe Tully-Fisher relation in the B-band and Ks-band for the present sample of\nM51-type systems is flatter when compared with isolated galaxies. Using the\nradial velocity data set, we built a synthetic normalized radial velocity\ndistribution, as a reference for future modeling of these peculiar systems. The\nsynthetic rotation curve, representing the typical rotation curve of the main\ngalaxy in an M51-type pair, is near to solid body-like inside 4 kpc, and then\nis nearly flat within the radial range 5-15 kpc. The relative position angles\nbetween the main galaxy major axis and the companion location, as well as the\nvelocity difference amplitude, indicate that the orbital motion of the\nsatellite has a large projection on the main galaxy equatorial plane. In\naddition, the radial velocity differences between the two galaxies indicate\nthat the satellite orbital motion is within the range of amplitudes of the main\ngalaxy rotation curve and all the M51-type systems studied here except for one,\nare gravitationally bounded." }, { "anchor": "Neutral ISM, Lyman-Alpha and Lyman-continuum in the nearby starburst\n Haro 11: Star forming galaxies are believed to be a major source of Lyman Continuum\n(LyC) radiation responsible for reionizing the early Universe. Direct\nobservations of escaping ionizing radiation have however been few and with low\nescape fractions. In the local Universe, only ~10 emitters have been observed,\nwith typical escape fractions of a few percent. The mechanisms regulating this\nescape need to be strongly evolving with redshift in order to account for the\nEpoch of Reionization. Gas content and star formation feedback are among the\nmain suspects, known to both regulate neutral gas coverage and evolve with\ncosmic time. In this paper, we reanalyze HST-COS spectrocopy of the first\ndetected local LyC leaker, Haro 11. We examine the connection between LyC\nleakage and Lyman-$\\alpha$ line shape, and feedback-influenced neutral ISM\nproperties like kinematics and gas distribution. We discuss the two extremes of\nan optically thin, density bounded ISM and a riddled, optically thick,\nionization bounded ISM, and how Haro 11 fits into their theoretical\npredictions. We find that the most likely ISM model is a clumpy neutral medium\nembedded in a highly ionized medium with a combined covering fraction of unity\nand a residual neutral gas column density in the ionized medium high enough to\nbe optically thick to Lyman-$\\alpha$, but low enough to be at least partly\ntransparent to Lyman continuum and undetected in Si II. This suggests that SF\nfeedback and galaxy-scale interaction events play a major role in opening\npassageways for ionizing radiation through the neutral medium.", "positive": "Modes of a stellar system II: non-ergodic systems: An equation is derived for the energy of a small disturbance in a system that\nis generated by a distribution function (DF) of the form $f(\\vJ)$ -- most\ngalaxies and star clusters can be closely approximated by such a DF. The theory\nof van Kampen modes is extended to such general systems. An inner product on\nthe space of DFs is defined such that the energy of a disturbance is its norm\nunder this product. It is shown that van Kampen modes that differ in frequency\nare then orthogonal, with the consequence that the energies of van Kampen modes\nare additive. Consequently, most of the insight into the dynamics of ergodic\nsystems that was gained in a recent paper on the van Kampen modes of ergodic\nsystems applies to real clusters and galaxies." }, { "anchor": "Cold gas in the heart of Perseus A: We present new JVLA and VLBA observations tracing the HI in the central\nregion of 3C84 (Perseus A). This radio source is hosted by the bright cluster\ngalaxy NGC 1275 in the centre of the iconic Perseus cluster. With the JVLA, we\ndetected broad (FWHM~500 km/s) HI absorption at arcsecond resolution (~300 pc)\ncentred at the systemic velocity of NGC 1275 against the bright radio\ncontinuum, suggesting that the detected gas is very close to the supermassive\nblack hole (SMBH). However, we did not detect any absorption in the\nhigher-resolution VLBA data against the parsec-scale radio core and jet. Based\non a comparison of the properties of the HI absorption with those of the\nmolecular circum-nuclear disc (CND) known to be present in NGC 1275, we argue\nthat the HI seen in absorption arises from HI in this fast-rotating CND, and\nthat neutral atomic hydrogen is present as close as ~20 pc from the SMBH. The\nradio continuum providing the background for absorption arises from non-thermal\nsynchrotron emission from the star formation activity in the CND, whose\npresence has been reported by earlier VLBA studies. We did not detect any\nsignature that the HI gas is affected by an interaction with the radio jet.\nThus, at this stage of the evolution of the source, the impact of the radio jet\non the gas in NGC 1275 mainly creates cavities on much larger galaxy scales.\nOverall, the properties of the CND in Perseus A present strong similarities\nwith Mrk 231, suggesting that, unlike often assumed, HI absorption can arise\nagainst the radio emission from star formation in a CND. With the JVLA, we\nserendipitously detected a new, faint absorbing system that is redshifted by\n~2660 km/s, in addition to the already known high-velocity absorption system\nthat is redshifted 2850 km/s with respect to NGC 1275. We identify this new\nsystem as gas that is stripped from a foreground galaxy falling into the\nPerseus cluster.", "positive": "The large-scale structure of the halo of the Andromeda galaxy II.\n Hierarchical structure in the Pan-Andromeda Archaeological Survey: The Pan-Andromeda Archaeological Survey is a survey of $>400$ square degrees\ncentered on the Andromeda (M31) and Triangulum (M33) galaxies that has provided\nthe most extensive panorama of a $L_\\star$ galaxy group to large projected\ngalactocentric radii. Here, we collate and summarise the current status of our\nknowledge of the substructures in the stellar halo of M31, and discuss\nconnections between these features. We estimate that the 13 most distinctive\nsubstructures were produced by at least 5 different accretion events, all in\nthe last 3 or 4 Gyrs. We suggest that a few of the substructures furthest from\nM31 may be shells from a single accretion event. We calculate the luminosities\nof some prominent substructures for which previous estimates were not\navailable, and we estimate the stellar mass budget of the outer halo of M31. We\nrevisit the problem of quantifying the properties of a highly structured\ndataset; specifically, we use the OPTICS clustering algorithm to quantify the\nhierarchical structure of M31's stellar halo, and identify three new faint\nstructures. M31's halo, in projection, appears to be dominated by two\n`mega-structures', that can be considered as the two most significant branches\nof a merger tree produced by breaking M31's stellar halo into smaller and\nsmaller structures based on the stellar spatial clustering. We conclude that\nOPTICS is a powerful algorithm that could be used in any astronomical\napplication involving the hierarchical clustering of points. The publication of\nthis article coincides with the public release of all PAndAS data products." }, { "anchor": "The MUSE Ultra Deep Field (MUDF). I. Discovery of a group of Ly$\u03b1$\n nebulae associated with a bright $z\\approx 3.23$ quasar pair: We present first results from Multi Unit Spectroscopic Explorer (MUSE)\nobservations at the Very Large Telescope in the MUSE Ultra Deep Field (MUDF), a\n$\\approx 1.2\\times 1.4$ arcmin$^2$ region for which we are collecting\n$\\approx$200 hours of integral field spectroscopy. The $\\approx 40$-hour\nobservation completed to date reveals the presence of a group of three\nLy$\\alpha$ nebulae associated with a bright quasar pair at $z\\simeq3.23$ with\nprojected separation of $\\approx 500\\rm~kpc$. Two of the nebulae are physically\nassociated with the quasars which are likely powering the Ly$\\alpha$ emission,\nand extend for $\\gtrsim 100~\\rm kpc$ at a surface brightness level of $\\approx\n6\\times 10^{-19}~\\rm erg~s^{-1}~cm^{-2}~arcsec^{-2}$. A third smaller\n($\\approx$35 kpc) nebula lies at a velocity offset of $\\approx 1550$ km\ns$^{-1}$. Despite their clustered nature, the two large nebulae have properties\nsimilar to those observed in isolated quasars and exhibit no sharp decline in\nflux at the current depth, suggesting an even more extended distribution of gas\naround the quasars. We interpret the shape and the alignment of the two\nbrighter nebulae as suggestive of the presence of an extended structure\nconnecting the two quasar host galaxies, as seen for massive galaxies forming\nwithin gas-rich filaments in cosmological simulations.", "positive": "Lopsidedness as a tracer of early galactic assembly history: Large-scale asymmetries (i.e. lopsidedness) are a common feature in the\nstellar density distribution of nearby disk galaxies both in low- and\nhigh-density environments. In this work, we characterize the present-day\nlopsidedness in a sample of 1435 disk-like galaxies selected from the TNG50\nsimulation. We find that the percentage of lopsided galaxies (10%-30%) is in\ngood agreement with observations if we use similar radial ranges to the\nobservations. However, the percentage (58%) significantly increases if we\nextend our measurement to larger radii. We find a mild or lack of correlation\nbetween lopsidedness amplitude and environment at z=0 and a strong correlation\nbetween lopsidedness and galaxy morphology regardless of the environment.\nPresent-day galaxies with more extended disks, flatter inner galactic regions\nand lower central stellar mass density (i.e. late-type disk galaxies) are\ntypically more lopsided than galaxies with smaller disks, rounder inner\ngalactic regions and higher central stellar mass density (i.e. early-type disk\ngalaxies). Interestingly, we find that lopsided galaxies have, on average, a\nvery distinct star formation history within the last 10 Gyr, with respect to\ntheir symmetric counterparts. Symmetric galaxies have typically assembled at\nearly times (~8-6 Gyr ago) with relatively short and intense bursts of central\nstar formation, while lopsided galaxies have assembled on longer timescales and\nwith milder initial bursts of star formation, continuing building up their mass\nuntil z=0. Overall, these results indicate that lopsidedness in present-day\ndisk galaxies is connected to the specific evolutionary histories of the\ngalaxies that shaped their distinct internal properties." }, { "anchor": "The galaxy population within the virial radius of the Perseus cluster: We investigate the galaxy population in a field of the Perseus cluster that\nroughly covers the virial radius of the cluster. The galaxies were selected on\nSchmidt CCD images in B and H alpha in combination with SDSS images. We present\na catalogue of 1294 galaxies. Morphological information was obtained for 90% of\nthe galaxies from the `eyeball' inspection, partly supported by the surface\nbrightness profile analysis. Redshifts were taken from SDSS, literature\nsources, and own spectroscopic observations and are available for 24% of the\ncatalogues galaxies. The galaxy catalogue is used to derive cluster properties,\nsuch as radial profiles, indications of sub-structure, virial mass, and viral\nradius and to study the cluster galaxy population with regard to morphological\ntypes and peculiarities, star formation rates and active galactic nuclei. In\naddition to the statistical approach, we present brief individual descriptions\nof 18 cluster galaxies with conspicuous morphological peculiarities. (Abstract\nmodified to match the arXiv format.)", "positive": "N-enhancement in GN-z11: First evidence for supermassive stars\n nucleosynthesis in proto-globular clusters-like conditions at high redshift ?: Unusually high N/O abundance ratios were recently reported for a very\ncompact, intensively star-forming object GN-z11 at $z=10.6$ from JWST/NIRSpec\nobservations. We present an empirical comparison with the C, N, and O abundance\nratios in Galactic globular clusters (GCs) over a large metallicity range. We\nshow that hot hydrogen-burning nucleosynthesis within supermassive stars (SMS)\nformed through runaway collisions can consistently explain the observed\nabundances ratio in GN-z11 and in GCs. This suggests that a proto-globular\ncluster hosting a SMS could be at the origin of the strong N-enrichment in\nGN-z11. Our model predicts the behavior of N/O, C/O, and Ne/O ratios as a\nfunction of metallicity, which can be tested if high-$z$ objects similar to\nGN-z11 are detected with JWST in the future. Further studies and statistics\nwill help differentiate the proto-GC scenario from the Wolf-Rayet scenario that\nwe quantify with a population synthesis model, and shed more light on this\npeculiar object." }, { "anchor": "Predictions on the stellar-to-halo mass relation in the dwarf regime\n using the empirical model for galaxy formation EMERGE: One of the primary goals when studying galaxy formation is to understand how\nthe luminous component of the Universe, galaxies, relates to the growth of\nstructure which is dominated by the gravitational collapse of dark matter\nhaloes. The stellar-to-halo mass relation probes how galaxies occupy dark\nmatter haloes and what that entails for their star formation history. We\ndeliver the first self-consistent empirical model that can place constraints on\nthe stellar-to-halo mass relation down to log stellar mass\n$\\log_{10}(m^*/\\mathrm{M}_{\\odot}) \\leq 5.0$ by fitting our model directly to\nLocal Group dwarf data. This is accomplished by penalising galaxy growth in\nlate-forming, low-mass haloes by mimicking the effects of reionization. This\nprocess serves to regulate the number density of galaxies by altering the\nscatter in halo peak mass $M^{\\mathrm{peak}}_{h}$ at fixed stellar mass,\ncreating a tighter scatter than would otherwise exist without a high-$z$\nquenching mechanism. Our results indicate that the previously established\ndouble-power law stellar-to-halo mass relation can be extended to include\ngalaxies with\n$\\log_{10}(M^{\\mathrm{peak}}_{\\mathrm{h}}/\\mathrm{M}_{\\odot})\\gtrsim 10.0$.\nFurthermore, we show that haloes with\n$\\log_{10}(M^{\\mathrm{peak}}_{\\mathrm{h}}/\\mathrm{M}_{\\odot})\\lesssim 9.3$ by\n$z=4$ are unlikely to host a galaxy with $\\log_{10}(m^*/\\mathrm{M}_{\\odot}) >\n5.0$.", "positive": "Small Molecules, Big Impact: A tale of hydrides past, present, and\n future: Formed at an early stage of gas-phase ion-molecule chemistry, hydrides --\nmolecules containing a heavy element covalently bonded to one or more hydrogen\natoms -- play an important role in interstellar chemistry as they are the\nprogenitors of larger and more complex species in the interstellar medium. In\nrecent years, the careful analysis of the spectral signatures of hydrides have\nled to their use as tracers of different constituents, and phases of the\ninterstellar medium and in particular the more diffuse environments. Diffuse\nclouds form an essential link in the stellar gas life-cycle as they connect\nboth the late and early stages of stellar evolution. As a result, diffuse\nclouds are continuously replenished by material which makes them reservoirs for\nheavy elements and hence ideal laboratories for the study of astrochemistry.\nThis review will journey through a renaissance of hydride observations\ndetailing puzzling hydride discoveries and chemical mysteries with special\nfocus carbon-bearing hydrides to demonstrate the big impact of these small\nmolecules and ending with remarks on the future of their studies." }, { "anchor": "Origin and z-distribution of Galactic diffuse [CII] emission: We determine the source of the diffuse [CII] emission by studying its spatial\n(radial and vertical) distributions. We used the HIFI [CII] Galactic survey\n(GOT C+), along with HI, 12CO, and 13CO data toward 354 lines of sight, and\nseveral HIFI [CII] and [CI] position-velocity maps. We quantified the emission\nin each spectral line profile by evaluating the intensities in 3 km/s wide\nvelocity bins, 'spaxels'. Using the detection of [CII] with CO or [CI], we\nseparated the dense and diffuse gas components. We derived 2-D Galactic disk\nmaps using the spaxel velocities for kinematic distances. We separated the warm\nand cold H2 gases by comparing CO emissions with and without associated [CII].\nWe find evidence of widespread diffuse [CII] emission with a z-scale\ndistribution larger than that for the total [CII] or CO. and it consists of (i)\ndiffuse molecular (CO-faint) H2 clouds and (ii) diffuse HI clouds and/or WIM.\nIn the inner Galaxy we find a lack of [CII] detections in a majority (~62%) of\nHI spaxels and show that the diffuse component primarily comes from the WIM\n(~21%) and that the HI gas is not a major contributor to the diffuse component\n(~6%). The warm-H2 radial profile shows an excess in the range 4 to 7 kpc,\nconsistent with enhanced star formation there. We derive, for the first time,\nthe 2-D [CII] spatial distribution in the plane and the z-distributions of the\nindividual [CII] gas component. We estimate the fractional [CII] emission\ntracing (i) H2 gas in dense and diffuse molecular clouds as ~48% and ~ 14%,\nrespectively, (ii) in the HI gas ~18%, and (iii) in the WIM ~21%. Including\nnon-detections from HI increases the [CII] in HI to ~ 27%. The z-scale\ndistributions FWHM are [CII] sources with CO, ~130 pc, (CO-faint) diffuse H2\ngas, ~200 pc, and the diffuse HI and WIM, ~330 pc. CO observations, when\ncombined with [CII], probe the warm-H2 gas, tracing star formation.", "positive": "Studying the molecular gas towards the R Coronae Australis dark cloud: The R Coronae Australis dark cloud is one of the closest star-forming regions\nto the Sun. The cloud is known to be very active in star formation, harboring\nmany Herbig-Haro objects (HHs) and Molecular Hydrogen emission-line Objects\n(MHOs). In this work we present results from molecular observations (a\n$5.5^{'}\\times5.5^{'}$ map of $^{12}$CO J$=3-2$ and HCO$^{+}$ J$=4-3$, and a\nsingle spectrum of N$_{2}$H$^{+}$ J$=4-3$) obtained with the Atacama\nSubmillimeter Telescope Experiment (ASTE) towards the R CrA dark cloud with an\nangular and spectral resolution of 22$^{\"}$ and 0.11 km s$^{-1}$, respectively.\nFrom the $^{12}$CO J$=3-2$ line we found kinematical spectral features strongly\nsuggesting the presence of outflows towards a region populated by several HHs\nand MHOs. Moreover, most of these objects lie within an HCO$^{+}$ maximum,\nsuggesting that its emission arises from an increasement of its abundance due\nto the chemistry triggered by the outflow activity. Additionally, we are\npresenting the first reported detection of N$_{2}$H$^{+}$ in the J$=4-3$ line\ntowards the R CrA dark cloud." }, { "anchor": "Collimated Fast Wind in the Pre-Planetary Nebula CRL 618: Collimated fast winds (CFWs) have been proposed to operate during the\npost-AGB evolutionary phase (and even earlier during the late AGB phase),\nresponsible for the shaping of pre-planetary nebulae (PPNs) and young planetary\nnebulae (PNs). This paper is a follow-up to our previous study of CFW models\nfor the well-studied PPN CRL 618. Previously, we compared our CFW models with\noptical observations of CRL 618 in atomic and ionic lines and found that a CFW\nwith a small opening angle can readily reproduce the highly collimated shape of\nthe northwestern (W1) lobe of CRL 618 and the bow-like structure seen at its\ntip. In this paper, we compare our CFW models with recent observations of CRL\n618 in CO J=2-1, J=6-5, and H2 1-0 S(1). In our models, limb-brightened shell\nstructures are seen in CO and H2 at low velocity arising from the shocked AGB\nwind in the shell, and can be identified as the low-velocity (LV) components in\nthe observations. However, the shell structure in CO J=2-1 is significantly\nless extended than that seen in the observations. None of our models can\nproperly reproduce the observed high-velocity (HV) molecular emission near the\nsource along the body of the lobe. In order to reproduce the HV molecular\nemission in CRL 618, the CFW is required to have a different structure. One\npossible CFW structure is the cylindrical jet, with the fast wind material\nconfined to a small cross section and collimated to the same direction along\nthe outflow axis.", "positive": "SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20: The SEGUE survey obtained 240,000 moderate resolution (R = 1800) spectra from\n3900 - 9000 Angstroms of fainter Milky Way stars (14.0 < g < 20.3) of a wide\nvariety of spectral types, both main sequence and evolved objects, with the\ngoal of studying the kinematics and populations of our Galaxy and its halo. The\nspectra are clustered in 212 regions spaced over three-quarters of the sky.\nRadial velocity accuracies for stars are 4 km/s at g < 18, degrading to 15 km/s\nat g = 20. For stars with S/N > 10 per resolution element, stellar atmospheric\nparameters are estimated, including metallicity, surface gravity, and effective\ntemperature. SEGUE obtained 3500 square degrees of additional ugriz imaging\n(primarily at low Galactic latitudes) providing precise multi-color photometry\n(g,r,i = 2%), (u,z = 3%) and astrometry (0.1 arcsec) for spectroscopic target\nselection. The stellar spectra, imaging data, and derived parameter catalogs\nfor this survey are publicly available as part of SDSS Data Release 7 (DR7)." }, { "anchor": "Spontaneous Formation of Outflows Powered by Rotating Magnetized\n Accretion Flows in a Galactic Center: We investigate how magnetically driven outflows are powered by a rotating,\nweakly magnetized accretion flow onto a supermassive black hole using\naxisymmetric magnetohydrodynamic simulations. Our proposed model focuses on the\naccretion dynamics on an intermediate scale between the Schwarzschild radius\nand the galactic scale, which is $\\sim$1-100 pc. We demonstrate that a rotating\ndisk formed on a parsec-scale acquires poloidal magnetic fields via accretion\nand this produces an asymmetric bipolar outflow at some point. The formation of\nthe outflow was found to follow the growth of strongly magnetized regions\naround disk surfaces (magnetic bubbles). The bipolar outflow grew continuously\ninside the expanding bubbles. We theoretically derived the growth condition of\nmagnetic bubbles for our model that corresponds to a necessary condition for\noutflow growth. We found that the north-south asymmetric structure of the\nbipolar outflow originates from the complex motions excited by accreting flows\naround the outer edge of the disk. The bipolar outflow comprises multiple\nmini-outflows and downflows (failed outflows). The mini-outflows emanate from\nthe magnetic concentrations (magnetic patches). The magnetic patches exhibit\ninward drifting motions, thereby making the outflows unsteady. We demonstrate\nthat the inward drift can be modeled using a simple magnetic patch model that\nconsiders magnetic angular momentum extraction. This study could be helpful for\nunderstanding how asymmetric and non-steady outflows with complex substructures\nare produced around supermassive black holes without the help of strong\nradiation from accretion disks or entrainment by radio jets such as molecular\noutflows in radio-quiet active galactic nuclei, NGC 1377.", "positive": "Evidence for non-merger co-evolution of galaxies and their supermassive\n black holes: Recent observational and theoretical studies have suggested that supermassive\nblack holes (SMBHs) grow mostly through non-merger (`secular') processes. Since\ngalaxy mergers lead to dynamical bulge growth, the only way to observationally\nisolate non-merger growth is to study galaxies with low bulge-to-total mass\nratio (e.g. B/T < 10%). However, bulge growth can also occur due to secular\nprocesses, such as disk instabilities, making disk-dominated selections a\nsomewhat incomplete way to select merger-free systems. Here we use the\nHorizon-AGN simulation to select simulated galaxies which have not undergone a\nmerger since z = 2, regardless of bulge mass, and investigate their location on\ntypical black hole-galaxy scaling relations in comparison to galaxies with\nmerger dominated histories. While the existence of these correlations has long\nbeen interpreted as co-evolution of galaxies and their SMBHs driven by galaxy\nmergers, we show here that they persist even in the absence of mergers. We find\nthat the correlations between SMBH mass and both total mass and stellar\nvelocity dispersion are independent of B/T ratio for both merger-free and\nmerger-dominated galaxies. In addition, the bulge mass and SMBH mass\ncorrelation is still apparent for merger-free galaxies, the intercept for which\nis dependent on B/T. Galaxy mergers reduce the scatter around the scaling\nrelations, with merger-free systems showing broader scatter. We show that for\nmerger-free galaxies, the co-evolution is dominated by radio-mode feedback, and\nsuggest that the long periods of time between galaxy mergers make an important\ncontribution to the co-evolution between galaxies and SMBHs in all galaxies." }, { "anchor": "On the Prevalence of Super-Massive Black Holes over Cosmic Time: We investigate the abundance of Super-Massive Black Hole (SMBH) seeds in\nprimordial galaxy halos. We explore the assumption that dark matter halos\noutgrowing a critical halo mass M_c have some probability p of having spawned a\nSMBH seed. Current observations of local, intermediate-mass galaxies constrain\nthese parameters: For $M_c=10^{11}M_\\odot$, all halos must be seeded, but when\nadopting smaller M_c masses the seeding can be much less efficient. The\nconstraints also put lower limits on the number density of black holes in the\nlocal and high-redshift Universe. Reproducing z~6 quasar space densities\ndepends on their typical halo mass, which can be constrained by counting nearby\nLyman Break Galaxies and Lyman Alpha Emitters. For both observables, our\nsimulations demonstrate that single-field predictions are too diverse to make\ndefinitive statements, in agreement with mixed claims in the literature. If\nquasars are not limited to the most massive host halos, they may represent a\ntiny fraction (~10^-5) of the SMBH population. Finally, we produce a wide range\nof predictions for gravitational events from SMBH mergers. We define a new\ndiagnostic diagram for LISA to measure both SMBH space density and the typical\ndelay between halo merger and black hole merger. While previous works have\nexplored specific scenarios, our results hold independent of the seed\nmechanism, seed mass, obscuration, fueling methods and duty cycle.", "positive": "In Search of Infall Motion in Molecular Clumps. IV. Mapping of the\n Global Infall Sources: We have used the IRAM 30-m telescope to map some targets with HCO$^+$ (1-0)\nand H$^{13}$CO$^+$ (1-0) lines in order to search for gas infall evidence in\nthe clumps. In this paper, we report the mapping results for 13 targets. All of\nthese targets show HCO$^+$ emissions, while H$^{13}$CO$^+$ emissions are\nobserved in ten of them. The HCO$^+$ integrated intensity maps of ten targets\nshow clear clumpy structures, and nine targets show clumpy structures in the\nH$^{13}$CO$^+$ maps. Using the RADEX radiative transfer code, we estimate the\ncolumn density of H$^{13}$CO$^+$, and determine the abundance ratio\n[H$^{13}$CO$^+$]/[H$_2$] to be approximately 10$^{-12}$ to 10$^{-10}$. Based on\nthe asymmetry of the HCO$^+$ line profiles, we identify 11 targets show blue\nprofiles, while six clumps have global infall evidence. We use the RATRAN and\ntwo-layer models to fit the HCO$^+$ line profiles of these infall sources, and\nanalyze their spatial distribution of the infall velocity. The average infall\nvelocities estimated by these two models are 0.24 -- 1.85 km s$^{-1}$ and 0.28\n-- 1.45 km s$^{-1}$, respectively. The mass infall rate ranges from\napproximately 10$^{-5}$ to 10$^{-2}$ M$_{\\odot}$ yr$^{-1}$, which suggests that\nintermediate- or high-mass stars may be forming in the target regions." }, { "anchor": "Tracing the Milky Way warp and spiral arms with classical Cepheids: Mapping the Galactic spiral structure is a difficult task since the Sun is\nlocated in the Galactic plane and because of dust extinction. For these\nreasons, molecular masers in radio wavelengths have been used with great\nsuccess to trace the Milky Way spiral arms. Recently, Gaia parallaxes have\nhelped in investigating the spiral structure in the Solar extended\nneighborhood. In this paper, we propose to determine the location of the spiral\narms using Cepheids since they are bright, young supergiants with accurate\ndistances (they are the first ladder of the extragalactic distance scale). They\ncan be observed at very large distances; therefore, we need to take the\nGalactic warp into account. Thanks to updated mid-infrared photometry and to\nthe most complete catalog of Galactic Cepheids, we derived the parameters of\nthe warp using a robust regression method. Using a clustering algorithm, we\nidentified groups of Cepheids after having corrected their Galactocentric\ndistances from the (small) effects of the warp. We derived new parameters for\nthe Galactic warp, and we show that the warp cannot be responsible for the\nincreased dispersion of abundance gradients in the outer disk reported in\nprevious studies. We show that Cepheids can be used to trace spiral arms, even\nat large distances from the Sun. The groups we identify are consistent with\nprevious studies explicitly deriving the position of spiral arms using young\ntracers (masers, OB(A) stars) or mapping overdensities of upper main-sequence\nstars in the Solar neighborhood thanks to Gaia data.", "positive": "The Dawn of Disk Formation in a Milky Way-sized Galaxy Halo: Thin\n Stellar Disks at $z > 4$: We present results from \\textsc{GigaEris}, a cosmological, $N$-body\nhydrodynamical \"zoom-in\" simulation of the formation of a Milky Way-sized\ngalaxy halo with unprecedented resolution, encompassing of order a billion\nparticles within the refined region. The simulation employs a modern\nimplementation of smoothed-particle hydrodynamics, including metal-line cooling\nand metal and thermal diffusion. We focus on the early assembly of the galaxy,\ndown to redshift $z=4.4$. The simulated galaxy has properties consistent with\nextrapolations of the main sequence of star-forming galaxies to higher\nredshifts and levels off to a star formation rate of $\\sim$60$\\,\nM_{\\odot}$~yr$^{-1}$ at $z=4.4$. A compact, thin rotating stellar disk with\nproperties analogous to those of low-redshift systems arises already at $z \\sim\n8$. The galaxy rapidly develops a multi-component structure, and the disk, at\nleast at these early stages, does not grow \"upside-down\" as often reported in\nthe literature. Rather, at any given time, newly born stars contribute to\nsustain a thin disk. The kinematics reflect the early, ubiquitous presence of a\nthin disk, as a stellar disk component with $v_\\phi/\\sigma_R$ larger than unity\nis already present at $z \\sim 9$--10. Our results suggest that high-resolution\nspectro-photometric observations of very high-redshift galaxies should find\nthin rotating disks, consistent with the recent discovery of cold rotating gas\ndisks by ALMA. Finally, we present synthetic images for the JWST NIRCam camera,\nshowing how the early disk would be easily detectable already at those early\ntimes." }, { "anchor": "Dissecting the Evolution of Dark Matter Subhaloes in the Bolshoi\n Simulation: We present a comprehensive analysis of the evolution of dark matter subhaloes\nin the cosmological Bolshoi simulation. We identify a complete set of 12 unique\nevolution channels by which subhaloes evolve in between simulation outputs, and\nstudy their relative importance and demographics. We show that instantaneous\nmasses and maximum circular velocities of individual subhaloes are extremely\nnoisy, despite the use of a sophisticated, phase-space-based halo finder. We\nalso show that subhaloes experience frequent penetrating encounters with other\nsubhaloes (on average about one per dynamical time), and that subhaloes whose\napo-center lies outside the virial radius of their host (the 'ejected' or\n'backsplash' haloes) experience tidal forces that modify their orbits. This\nresults in an average fractional subhalo exchange rate among host haloes of\nroughly 0.01 per Gyr (at the present time). In addition, we show that there are\nthree distinct disruption channels; one in which subhaloes drop below the mass\nresolution limit of the simulation, one in which subhaloes merge with their\nhost halo largely driven by dynamical friction, and one in which subhaloes\nabruptly disintegrate. We estimate that roughly 80 percent of all subhalo\ndisruption in the Bolshoi simulation is numerical, rather than physical. This\nover-merging is a serious road-block for the use of numerical simulations to\ninterpret small scale clustering, or for any other study that is sensitive to\nthe detailed demographics of dark matter substructure.", "positive": "Degeneracies between baryons and dark matter: the challenge of\n constraining the nature of dark matter with JWST: The James Webb Space Telescope (JWST) will revolutionise our understanding of\nearly galaxy formation, and could potentially set stringent constraints on the\nnature of dark matter. We use a semi-empirical model of galaxy formation to\ninvestigate the extent to which uncertainties in the implementation of baryonic\nphysics may be degenerate with the predictions of two different models of dark\nmatter -- Cold Dark Matter (CDM) and a 7 keV sterile neutrino, which behaves as\nWarm Dark Matter (WDM). Our models are calibrated to the observed UV luminosity\nfunction at $z=4$ using two separate dust attenuation prescriptions, which\nmanifest as high and low star formation efficiency in low mass haloes. We find\nthat while at fixed star formation efficiency, $\\varepsilon$, there are marked\ndifferences in the abundance of faint galaxies in the two dark matter models at\nhigh-$z$, these differences are mimicked easily by varying $\\varepsilon$ in the\nsame dark matter model. We find that a high $\\varepsilon$ WDM and a low\n$\\varepsilon$ CDM model -- which provide equally good fits to the $z=4$ UV\nluminosity function -- exhibit nearly identical evolution in the cosmic stellar\nmass and star formation rate densities. We show that differences in the star\nformation rate at fixed stellar mass are larger for variations in $\\varepsilon$\nin a given dark matter model than they are between dark matter models; however,\nthe scatter in star formation rates is larger between the two models than they\nare when varying $\\varepsilon$. Our results suggest that JWST will likely be\nmore informative in constraining baryonic processes operating in high-$z$\ngalaxies than it will be in constraining the nature of dark matter." }, { "anchor": "KAT-7 Science Verification: Cold Gas, Star Formation, and Substructure\n in the Nearby Antlia Cluster: The Antlia Cluster is a nearby, dynamically young structure, and its\nproximity provides a valuable opportunity for detailed study of galaxy and\ngroup accretion onto clusters. We present a deep HI mosaic completed as part of\nspectral line commissioning of the Karoo Array Telescope (KAT-7), and identify\ninfrared counterparts from the WISE extended source catalog to study neutral\natomic gas content and star formation within the cluster. We detect 37 cluster\nmembers out to a radius of ~0.9 Mpc with M_HI > 5x10^7 M_Sun. Of these, 35 are\nnew HI detections, 27 do not have previous spectroscopic redshift measurements,\nand one is the Compton thick Seyfert II, NGC 3281, which we detect in HI\nabsorption. The HI galaxies lie beyond the X-ray emitting region 200 kpc from\nthe cluster center and have experienced ram pressure stripping out to at least\n600 kpc. At larger radii, they are distributed asymmetrically suggesting\naccretion from surrounding filaments. Combining HI with optical redshifts, we\nperform a detailed dynamical analysis of the internal substructure, identify\nlarge infalling groups, and present the first compilation of the large scale\ndistribution of HI, and star forming galaxies within the cluster. We find that\nelliptical galaxy NGC 3268 is at the center of the oldest substructure and\nargue that NGC 3258 and its companion population are more recent arrivals.\nThrough the presence of HI and on-going star formation, we rank substructures\nwith respect to their relative time since accretion onto Antlia.", "positive": "Quark Nugget Dark Matter: Comparison with radio observations of nearby\n galaxies: It has been recently claimed that radio observations of nearby spiral\ngalaxies essentially rule out a dark matter source for the galactic haze. Here\nwe consider the low energy thermal emission from a quark nugget dark matter\nmodel in the context of microwave emission from the galactic centre and radio\nobservations of nearby Milky Way like galaxies. We demonstrate that observed\nemission levels do not strongly constrain this specific dark matter candidate\nacross a broad range of the allowed parameter space in drastic contrast with\nconventional dark matter models based on the WIMP paradigm." }, { "anchor": "Degree of Polarization and Source Counts of Faint Radio Sources from\n Stacking Polarized Intensity: We present stacking polarized intensity as a means to study the polarization\nof sources that are too faint to be detected individually in surveys of\npolarized radio sources. Stacking offers not only high sensitivity to the\nmedian signal of a class of radio sources, but also avoids a detection\nthreshold in polarized intensity, and therefore an arbitrary exclusion of\nsource with a low percentage of polarization. Correction for polarization bias\nis done through a Monte Carlo analysis and tested on a simulated survey. We\nshow that the non-linear relation between the real polarized signal and the\ndetected signal requires knowledge of the shape of the distribution of\nfractional polarization, which we constrain using the ratio of the upper\nquartile to the lower quartile of the distribution of stacked polarized\nintensities. Stacking polarized intensity for NVSS sources down to the\ndetection limit in Stokes I, we find a gradual increase in median fractional\npolarization that is consistent with a trend that was noticed before for bright\nNVSS sources, but is much more gradual than found by previous deep surveys of\nradio polarization. Consequently, the polarized radio source counts derived\nfrom our stacking experiment predict fewer polarized radio sources for future\nsurveys with the Square Kilometre Array and its pathfinders.", "positive": "Mathematics of Gravitational Lensing: Multiple Imaging and Magnification: The mathematical theory of gravitational lensing has revealed many generic\nand global properties. Beginning with multiple imaging, we review\nMorse-theoretic image counting formulas and lower bound results, and\ncomplex-algebraic upper bounds in the case of single and multiple lens planes.\nWe discuss recent advances in the mathematics of stochastic lensing, discussing\na general formula for the global expected number of minimum lensed images as\nwell as asymptotic formulas for the probability densities of the microlensing\nrandom time delay functions, random lensing maps, and random shear, and an\nasymptotic expression for the global expected number of micro-minima. Multiple\nimaging in optical geometry and a spacetime setting are treated. We review\nglobal magnification relation results for model-dependent scenarios and cover\nrecent developments on universal local magnification relations for higher order\ncaustics." }, { "anchor": "What can the Occult do for you? STarlight Attenuation & Reddening Survey\n of Multiple Occulting Galaxies (STARSMOG): Interstellar dust is still the dominant uncertainty in Astronomy, limiting\nprecision in e.g., cosmological distance estimates and models of how light is\nre-processed within a galaxy. When a foreground galaxy serendipitously overlaps\na more distant one, the latter backlights the dusty structures in the nearer\nforeground galaxy. Such an overlapping or occulting galaxy pair can be used to\nmeasure the distribution of dust in the closest galaxy with great accuracy. The\nSTARSMOG program uses HST observation of occulting galaxy pairs to accurately\nmap the distribution of dust in foreground galaxies in fine ($<$100 pc) detail.\nFurthermore, Integral Field Unit observations of such pairs will map the\neffective extinction curve in these occulting galaxies, disentangling the role\nof fine-scale geometry and grain composition on the path of light through a\ngalaxy.\n The overlapping galaxy technique promises to deliver a clear understanding of\nthe dust in galaxies: the dust geometry, a probability function of the amount\nof dimming as a function of galaxy type, its dependence on wavelength, and\nevolution of all these properties with cosmic time using distant, high-redshift\npairs.", "positive": "Spiral instabilities: Mode saturation and decay: This paper continues a series reporting different aspects of the behaviour of\ndisc galaxy simulations that support spiral instabilities. The focus in this\npaper is to demonstrate how linear spiral instabilities saturate and decay, and\nhow the properties of the disc affect the limiting amplitude of the spirals.\nOnce again, we employ idealized models that each possess a single instability\nthat we follow until it has run its course. Remarkably, we find a tight\ncorrelation between the growth rate of the mode and its limiting amplitude,\nalbeit from only six simulations. We show that non-linear orbit deflections\nnear corotation cause the mode to saturate, and that the more time available in\na slowly-growing mode creates the critical deflections at lower amplitude. We\nalso find that scattering at the inner Lindblad resonance is insignificant\nuntil after the mode has saturated. Our objective in this series of papers,\nwhich we believe we have now achieved, has been to develop a convincing and\nwell-documented account of the physical behaviour of the spiral patterns that\nhave been observed in simulations by others, and by ourselves, for many\ndecades. Understanding the simulations is an important step towards the greater\nobjective, which is to find observational evidence from galaxies that could\nconfront the identified mechanism." }, { "anchor": "The Chemical Compositions of Accreted and {\\it in situ} Galactic\n Globular Clusters According to SDSS/APOGEE: Studies of the kinematics and chemical compositions of Galactic globular\nclusters (GCs) enable the reconstruction of the history of star formation,\nchemical evolution, and mass assembly of the Galaxy. Using the latest data\nrelease (DR16) of the SDSS/APOGEE survey, we identify 3,090 stars associated\nwith 46 GCs. Using a previously defined kinematic association, we break the\nsample down into eight separate groups and examine how the kinematics-based\nclassification maps into chemical composition space, considering only $\\alpha$\n(mostly Si and Mg) elements and Fe. Our results show that: (i) The loci of both\nin situ and accreted subgroups in chemical space match those of their field\ncounterparts; (ii) GCs from different individual accreted subgroups occupy the\nsame locus in chemical space. This could either mean that they share a similar\norigin or that they are associated with distinct satellites which underwent\nsimilar chemical enrichment histories; (iii) The chemical compositions of the\nGCs associated with the low orbital energy subgroup defined by Massari and\ncollaborators is broadly consistent with an in situ origin. However, at the low\nmetallicity end, the distinction between accreted and in situ populations is\nblurred; (iv) Regarding the status of GCs whose origin is ambiguous, we\nconclude the following: the position in Si-Fe plane suggests an in situ}origin\nfor Liller 1 and a likely accreted origin for NGC 5904 and NGC 6388. The case\nof NGC 288 is unclear, as its orbital properties suggest an accretion origin,\nits chemical composition suggests it may have formed in situ.", "positive": "The stellar mass function, binary content and radial structure of the\n open cluster Praesepe derived from PPMXL and SDSS data: We have determined possible cluster members of the nearby open cluster\nPraesepe (M44) based on J and K photometry and proper motions from the PPMXL\ncatalogue and z photometry from the Sloan Digital Sky Survey (SDSS). In total\nwe identified 893 possible cluster members down to a magnitude of J = 15.5 mag,\ncorresponding to a mass of about 0.15 Msun for an assumed cluster distance\nmodulus of (m-M)_0 = 6.30 mag (d ~ 182 pc), within a radius of 3.5{\\deg} around\nthe cluster centre. We derive a new cluster centre for Praesepe\n({\\alpha}_centre = 8h 39m 37s, {\\delta}_centre = 19{\\deg} 35' 02\"). We also\nderive a total cluster mass of about 630 Msun and a 2D half-number and\nhalf-mass radius of 4.25 pc and 3.90 pc respectively. The global mass function\n(MF) of the cluster members shows evidence for a turnover around m = 0.65 Msun.\nWhile more massive stars can be fit by a power-law {\\xi}(m) ~ m^(-{\\alpha})\nwith slope {\\alpha} = 2.88 +/- 0.22, stars less massive than m = 0.65 Msun are\nbest fitted with {\\alpha} = 0.85 +/- 0.10. In agreement with its large\ndynamical age, we find that Praesepe is strongly mass segregated and that the\nmass function slope for high mass stars steepens from a value of {\\alpha} =\n2.32 +/- 0.24 inside the half-mass radius to {\\alpha} = 4.90 +/- 0.51 outside\nthe half-mass radius. We finally identify a significant population of binaries\nand triples in the colour-magnitude diagram of Praesepe. Assuming non-random\npairing of the binary components, a binary fraction of about 35% for primaries\nin the mass range 0.6 < m/Msun < 2.20 is required to explain the observed\nnumber of binaries in the colour-magnitude diagram (CMD)." }, { "anchor": "Detecting floating black holes as they traverse the gas disk of the\n Milky Way: A population of intermediate-mass black holes (BHs) is predicted to be freely\nfloating in the Milky Way (MW) halo, due to gravitational wave recoil, ejection\nfrom triple BH systems, or tidal stripping in the dwarf galaxies that merged to\nmake the MW. As these BHs traverse the gaseous MW disk, a bow shock forms,\nproducing detectable radio and mm/sub-mm synchrotron emission from accelerated\nelectrons. We calculate the synchrotron flux to be $\\sim \\rm 0.01-10\\, mJy$ at\nGHz frequency, detectable by Jansky Very Large Array, and $\\sim 10-100\\,\\mu\\rm\nJy$ at $\\sim10^{10}-10^{12} \\,\\rm Hz$ frequencies, detectable by Atacama Large\nMillimeter/sub-millimter Array. The discovery of the floating BH population\nwill provide insights on the formation and merger history of the MW as well as\non the evolution of massive BHs in the early Universe.", "positive": "Observational constraints to boxy/peanut bulge formation time: Boxy/peanut bulges are considered to be part of the same stellar structure as\nbars and both could be linked through the buckling instability. The Milky Way\nis our closest example. The goal of this letter is determining if the mass\nassembly of the different components leaves an imprint in their stellar\npopulations allowing to estimate the time of bar formation and its evolution.\nTo this aim we use integral field spectroscopy to derive the stellar age\ndistributions, SADs, along the bar and disc of NGC 6032. The analysis shows\nclearly different SADs for the different bar areas. There is an underlying old\n(>=12 Gyr) stellar population for the whole galaxy. The bulge shows star\nformation happening at all times. The inner bar structure shows stars of ages\nolder than 6 Gyrs with a deficit of younger populations. The outer bar region\npresents a SAD similar to that of the disc. To interpret our results, we use a\ngeneric numerical simulation of a barred galaxy. Thus, we constrain, for the\nfirst time, the epoch of bar formation, the buckling instability period and the\nposterior growth from disc material. We establish that the bar of NGC 6032 is\nold, formed around 10 Gyr ago while the buckling phase possibly happened around\n8 Gyr ago. All these results point towards bars being long-lasting even in the\npresence of gas." }, { "anchor": "Star clusters as building blocks for dSph galaxies formation: We study numerically the formation of dSph galaxies. Intense star bursts,\ne.g. in gas-rich environments, typically produce a few to a few hundred young\nstar clusters, within a region of just a few hundred pc. The dynamical\nevolution of these star clusters may explain the formation of the luminous\ncomponent of dwarf spheroidal galaxies (dSph). Here we perform a numerical\nexperiment to show that the evolution of star clusters complexes in dark matter\nhaloes can explain the formation of the luminous components of dSph galaxies.", "positive": "The Global Dynamical Atlas of the Milky Way mergers: Constraints from\n Gaia EDR3 based orbits of globular clusters, stellar streams and satellite\n galaxies: The Milky Way halo was predominantly formed by the merging of numerous\nprogenitor galaxies. However, our knowledge of this process is still\nincomplete, especially in regard to the total number of mergers, their global\ndynamical properties and their contribution to the stellar population of the\nGalactic halo. Here, we uncover the Milky Way mergers by detecting groupings of\nglobular clusters, stellar streams and satellite galaxies in action\n($\\mathbf{J}$) space. While actions fully characterize the orbits, we\nadditionally use the redundant information on their energy ($\\textit{E}$) to\nenhance the contrast between groupings. For this endeavour, we use\n$\\textit{Gaia}$ EDR3 based measurements of $170$ globular clusters, $41$\nstreams and $46$ satellites to derive their $\\mathbf{J}$ and $\\textit{E}$. To\ndetect groups, we use the $\\texttt{ENLINK}$ software, coupled with a\nstatistical procedure that accounts for the observed phase-space uncertainties\nof these objects. We detect a total of $N=6$ groups, including the previously\nknown mergers $\\textit{Sagittarius}$, $\\textit{Cetus}$,\n$\\textit{Gaia-Sausage/Enceladus}$, $\\textit{LMS-1/Wukong}$,\n$\\textit{Arjuna/Sequoia/I'itoi}$ and one new merger that we call\n$\\textit{Pontus}$. All of these mergers, together, comprise $62$ objects\n($\\approx 25\\%$ of our sample). We discuss their members, orbital properties\nand metallicity distributions. We find that the three most metal-poor streams\nof our Galaxy -- \"C-19\" ([Fe/H]$=-3.4$ dex), \"Sylgr\" ([Fe/H]$=-2.9$ dex) and\n\"Phoenix\" ([Fe/H]$=-2.7$ dex) -- are associated with $\\textit{LMS-1/Wukong}$;\nshowing it to be the most metal-poor merger. The global dynamical atlas of\nMilky Way mergers that we present here provides a present-day reference for\ngalaxy formation models." }, { "anchor": "Modeling the H2O submillimeter emission in extragalactic sources: Recent observational studies have shown that H2O emission at (rest)\nsubmillimeter wavelengths is ubiquitous in infrared galaxies, both in the local\nand in the early Universe, suggestive of far-infrared pumping of H2O by dust in\nwarm regions. In this work, models are presented that show that (i) the\nhighest-lying H2O lines (E_{upper}>400 K) are formed in very warm (T_{dust}>~90\nK) regions and require high H2O columns (N_{H2O}>~3x10^{17} cm^{-2}), while\nlower lying lines can be efficiently excited with T_{dust}~45-75 K and\nN_{H2O}~(0.5-2)x10^{17} cm^{-2}; (ii) significant collisional excitation of the\nlowest lying (E_{upper}<200 K) levels, which enhances the overall\nL_{H2O}-L_{IR} ratios, is identified in sources where the ground-state para-H2O\n1_{11}-0_{00} line is detected in emission; (iii) the H2O-to-infrared (8-1000\num) luminosity ratio is expected to decrease with increasing T_{dust} for all\nlines with E_{upper}<~300 K, as has recently been reported in a sample of\nLIRGs, but increases with T_{dust} for the highest lying H2O lines\n(E_{upper}>400 K); (iv) we find theoretical upper limits for L_{H2O}/L_{IR} in\nwarm environments, owing to H2O line saturation; (v) individual models are\npresented for two very different prototypical galaxies, the Seyfert 2 galaxy\nNGC 1068 and the nearest ultraluminous infrared galaxy Arp 220, showing that\nthe excited submillimeter H2O emission is dominated by far-infrared pumping in\nboth cases; (vi) the L_{H2O}-L_{IR} correlation previously reported in\nobservational studies indicates depletion or exhaustion time scales,\nt_{dep}=Sigma_{gas}/Sigma_{SFR}, of <~12 Myr for star-forming sources where\nlines up to E_{upper}=300 K are detected, in agreement with the values\npreviously found for (U)LIRGs from HCN millimeter emission...", "positive": "On the environmental influence of groups and clusters of galaxies beyond\n the virial radius: Galactic conformity at few Mpc scales: The environment within dark matter haloes can quench the star formation of\ngalaxies. However, environmental effects beyond the virial radius of haloes\n($\\gtrsim$ 1 Mpc) are less evident. An example is the debated correlation\nbetween colour or star formation in central galaxies and neighbour galaxies in\nadjacent haloes at large separations of several Mpc, referred to as two-halo\ngalactic conformity. We use two galaxy catalogues generated from different\nversions of the semi-analytic model SAG applied to the MDPL2 cosmological\nsimulation and the IllustrisTNG300 cosmological hydrodynamical simulation to\nstudy the two-halo conformity by measuring the quenched fraction of\nneighbouring galaxies as a function of the real-space distance from central\ngalaxies. We find that low-mass central galaxies in the vicinity of massive\nsystems ($M_{\\rm 200c}$ $\\geq$ 10$^{13}$ $h^{-1}~\\rm M_{\\odot}$) out to 5\n$h^{-1}$ Mpc are preferentially quenched compared to other central galaxies at\nfixed stellar mass $M_{\\star}$ or fixed host halo mass $M_{\\rm 200c}$ at $z$ ~\n0. In all the galaxies catalogues is consistent that the low-mass ($M_{\\star} <\n10^{10}$ $h^{-1}~\\rm M_{\\odot}$ or $M_{\\rm 200c} < 10^{11.8}$ $h^{-1}~\\rm\nM_{\\odot}$) central galaxies in the vicinity of clusters and, especially,\ngroups of galaxies mostly produce the two-halo galactic conformity. On average,\nthe quenched low-mass central galaxies are much closer to massive haloes than\nstar-forming central galaxies of the same mass (by a factor of ~5). Our results\nagree with other works regarding the environmental influence of massive haloes\nthat can extend beyond the virial radius and affect nearby low-mass central\ngalaxies." }, { "anchor": "Mapping physical parameters in Orion KL at high spatial resolution: The Orion Kleinmann-Low nebula (Orion KL) is notoriously complex and exhibits\na range of physical and chemical components. We conducted high angular\nresolution (sub-arcsecond) observations of $^13$CH$_{3}$OH $\\nu=0$\n($\\sim$0.3$^{\\prime\\prime}$ and $\\sim$0.7$^{\\prime\\prime}$) and CH$_3$CN\n$\\nu_8=1$ ($\\sim$0.2$^{\\prime\\prime}$ and $\\sim$0.9$^{\\prime\\prime}$) line\nemission with the Atacama Large Millimeter/submillimeter Array (ALMA) to\ninvestigate Orion KL's structure on small spatial scales (${\\le}350$ au). Gas\nkinematics, excitation temperatures, and column densities were derived from the\nmolecular emission via a pixel-by-pixel spectral line fitting of the image\ncubes, enabling us to examine the small-scale variation of these parameters.\nSub-regions of the Hot Core have a higher excitation temperature in a\n0.2$^{\\prime\\prime}$ beam than a 0.9$^{\\prime\\prime}$ beam, indicative of\npossible internal sources of heating. Furthermore, the velocity field includes\na bipolar ${\\sim}7{-}8$ km s$^{-1}$ feature with a southeast-northwest\norientation against the surrounding ${\\sim}4{-}5$ km s$^{-1}$ velocity field,\nwhich may be due to an outflow. We also find evidence of a possible source of\ninternal heating toward the Northwest Clump, since the excitation temperature\nthere is higher in a smaller beam versus a larger beam. Finally, the region\nsouthwest of the Hot Core (Hot Core-SW) presents itself as a particularly\nheterogeneous region bridging the Hot Core and Compact Ridge. Additional\nstudies to identify the (hidden) sources of luminosity and heating within Orion\nKL are necessary to better understand the nebula and its chemistry.", "positive": "VEGAS: A VST Early-type GAlaxy Survey. III. Mapping the galaxy\n structure, interactions and intragroup light in the NGC 5018 group: Most of the galaxies in the Universe at present day are in groups, which are\nkey to understanding the galaxy evolution. In this work we present a new deep\nmosaic of 1.2 x 1.0 square degrees of the group of galaxies centered on NGC\n5018, acquired at the ESO VLT Survey Telescope. We use u, g, r images to\nanalyse the structure of the group members and to estimate the intra-group\nlight. Taking advantage of the deep and multiband photometry and of the large\nfield of view of the VST telescope, we studied the structure of the galaxy\nmembers and the faint features into the intra-group space and we give an\nestimate of the intragroup diffuse light in the NGC 5018 group of galaxies. We\nfound that ~ 41% of the total g-band luminosity of the group is in the form of\nintragroup light (IGL). The IGL has a (g - r) color consistent with those of\nother galaxies in the group, indicating that the stripping leading to the\nformation of IGL is ongoing. From the study of this group we can infer that\nthere are at least two different interactions involving the group members: one\nbetween NGC 5018 and NGC 5022, which generates the tails and ring-like\nstructures detected in the light, and another between NGC 5022 and\nMCG-03-34-013 that have produced the HI tail. A minor merging event also\nhappened in the formation history of NGC 5018 that have perturbed the inner\nstructure of this galaxy." }, { "anchor": "Kinematically Identified Recoiling Supermassive Black Hole Candidates in\n SDSS QSOs with z $<$ 0.25: We have performed a spectral decomposition to search for recoiling\nsupermassive black holes (rSMBH) in the SDSS QSOs with $z<0.25$. Out of 1271\nQSOs, we have identified 26 rSMBH candidates that are recoiling toward us. The\nprojected recoil velocities range from $-76\\ \\kms$ to $-307\\ \\kms$ with a mean\nof $-149\\pm58\\ \\kms$. Most of the rSMBH candidates are hosted by gas-rich\nLIRGs/ULIRGs, but only 23\\% of them shows signs of tidal features suggesting\nmajority of them are advanced mergers. We find that the black hole masses\n$M_{BH}$ of the rSMBH candidates are on average $\\sim$5 times smaller than that\nof their stationary counterparts and cause a scatter in $M_{BH}-\\sigma_*$\nrelation. The Eddington ratios of all of the rSMBH candidates are larger than\n0.1, with mean of 0.52$\\pm$0.27, suggesting they are actively accreting mass.\nVelocity shifts in high-excitation coronal lines suggest that the rSMBH\ncandidates are recoiling with an average velocity of about $-265\\ \\kms$.\nElectron density in the narrow line region of the H II rSMBH candidates is\nabout 1/10 of that in AGN rSMBH candidates probably because AGN in the former\nwas more spatially offset than that in the latter. The estimated spatial\noffsets between the rSMBH candidate and center of host galaxy range from\n0.21\\as \\ to 1.97\\as \\ and need to be confirmed spatially with high-resolution\nadaptive optics imaging observations.", "positive": "Survey Observations to Study Chemical Evolution from High-Mass Starless\n Cores to High-Mass Protostellar Objects II. HC$_{3}$N and N$_{2}$H$^{+}$: We have carried out survey observations of molecular emission lines from\nHC$_{3}$N, N$_{2}$H$^{+}$, CCS, and cyclic-C$_{3}$H$_{2}$ in the 81$-$94 GHz\nband toward 17 high-mass starless cores (HMSCs) and 28 high-mass protostellar\nobjects (HMPOs) with the Nobeyama 45-m radio telescope. We have detected\nN$_{2}$H$^{+}$ in all of the target sources except one and HC$_{3}$N in 14\nHMSCs and in 26 HMPOs. We investigate the $N$(N$_{2}$H$^{+}$)/$N$(HC$_{3}$N)\ncolumn density ratio as a chemical evolutionary indicator of massive cores.\nUsing the Kolmogorov-Smirnov (K-S) test and Welch's t test, we confirm that the\n$N$(N$_{2}$H$^{+}$)/$N$(HC$_{3}$N) ratio decreases from HMSCs to HMPOs. This\ntendency in high-mass star-forming regions is opposite to that in low-mass\nstar-forming regions. Furthermore, we found that the detection rates of\ncarbon-chain species (HC$_{3}$N, HC$_{5}$N, and CCS) in HMPOs are different\nfrom those in low-mass protostars. The detection rates of cyanopolyynes\n(HC$_{3}$N and HC$_{5}$N) are higher and that of CCS is lower in high-mass\nprotostars, compared to low-mass protostars. We discuss a possible\ninterpretation for these differences." }, { "anchor": "Caltech-NRAO Stripe 82 Survey (CNSS) Paper V: AGNs that transitioned to\n radio-loud state: A recent multi-year Caltech-NRAO Stripe 82 Survey (CNSS) revealed a group of\nobjects that appeared as new radio sources after $>$5--20 years of absence.\nThey are transient phenomena with respect to the Faint Images of the Radio Sky\nat Twenty Centimeters (FIRST) survey and constitute the first unbiased sample\nof renewed radio activity. Here we present the follow-up, radio, optical and\nX-ray study of them. The group consist of 12 sources, both quasars and galaxies\nwith wide redshift ($\\rm 0.04 < z < 1.7$) and luminosity ($\\rm\n2224.5$) distribution. Their radio properties\nin the first phase of activity, namely the convex spectra and compact\nmorphology, allow them all to be classified as gigahertz-peaked spectrum (GPS)\nsources. We conclude that the spectral changes are a consequence of the\nevolution of newly-born radio jets. Our observations show that over the next\nfew years of activity the GPS galaxies keep the convex shape of the spectrum,\nwhile GPS quasars rapidly transform into flat-spectrum sources, which may\nresult in them not being recognized as young sources. The wide range of\nbolometric luminosities, black hole masses and jet powers among the transient\nsources indicates even greater population diversity in the group of young radio\nobjects. We also suggest that small changes of the accretion disc luminosity\n(accretion rate) may be sufficient to ignite low-power radio activity that\nevolves on the scale of decades.", "positive": "Expanding bubbles in Orion A: [CII] observations of M42, M43, and NGC\n 1977: The Orion Molecular Cloud is the nearest massive-star forming region. Massive\nstars have profound effects on their environment due to their strong radiation\nfields and stellar winds. Velocity-resolved observations of the [CII]\n$158\\,\\mu\\mathrm{m}$ fine-structure line allow us to study the kinematics of\nUV-illuminated gas. Here, we present a square-degree-sized map of [CII]\nemission from the Orion Nebula complex obtained by the upGREAT instrument\nonboard SOFIA, covering the entire Orion Nebula (M42) plus M43 and the nebulae\nNGC 1973, 1975, and 1977. We compare the stellar characteristics of these three\nregions with the kinematics of the expanding bubbles surrounding them. The\nbubble blown by the O7V star $\\theta^1$ Ori C in the Orion Nebula expands\nrapidly, at $13\\,\\mathrm{km\\,s^{-1}}$. Simple analytical models reproduce the\ncharacteristics of the hot interior gas and the neutral shell of this\nwind-blown bubble and give us an estimate of the expansion time of\n$0.2\\,\\mathrm{Myr}$. M43 with the B0.5V star NU Ori also exhibits an expanding\nbubble structure, with an expansion velocity of $6\\,\\mathrm{km\\,s^{-1}}$.\nComparison with analytical models for the pressure-driven expansion of H\\,{\\sc\nii} regions gives an age estimate of $0.02\\,\\mathrm{Myr}$. The bubble\nsurrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionis\nexpands at $1.5\\,\\mathrm{km\\,s^{-1}}$, likely due to the over-pressurized\nionized gas as in the case of M43. We derive an age of $0.4\\,\\mathrm{Myr}$ for\nthis structure. We conclude that the bubble of the Orion Nebula is driven by\nthe mechanical energy input by the strong stellar wind from $\\theta^1$ Ori C,\nwhile the bubbles associated with M43 and NGC 1977 are caused by the thermal\nexpansion of the gas ionized by their central later-type massive stars." }, { "anchor": "Galaxy And Mass Assembly (GAMA): Data Release 4 and the z < 0.1 total\n and z < 0.08 morphological galaxy stellar mass functions: In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our\nfull spectroscopic redshift sample. This includes 248682 galaxy spectra, and,\nin combination with earlier surveys, results in 330542 redshifts across five\nsky regions covering ~250deg^2. The redshift density, is the highest available\nover such a sustained area, has exceptionally high completeness (95 per cent to\nr_KIDS=19.65mag), and is well suited for the study of galaxy mergers, galaxy\ngroups, and the low redshift (z<0.25) galaxy population. DR4 includes 32\nvalue-added tables or Data Management Units (DMUs) that provide a number of\nmeasured and derived data products including GALEX, ESO KiDS, ESO VIKING, WISE\nand Herschel Space Observatory imaging. Within this release, we provide visual\nmorphologies for 15330 galaxies to z<0.08, photometric redshift estimates for\nall 18million objects to r_KIDS~25mag, and stellar velocity dispersions for\n111830 galaxies. We conclude by deriving the total galaxy stellar mass function\n(GSMF) and its sub-division by morphological class (elliptical, compact-bulge\nand disc, diffuse-bulge and disc, and disc only). This extends our previous\nmeasurement of the total GSMF down to 10^6.75 M_sol h^-2_70 and we find a total\nstellar mass density of rho_*=(2.97+/-0.04)x10^8 M_sol h_70 Mpc^-3 or\nOmega_*=(2.17+/-0.03)x10^-3 h^-1_70. We conclude that at z<0.1, the Universe\nhas converted 4.9+/-0.1 per cent of the baryonic mass implied by Big Bang\nNucleosynthesis into stars that are gravitationally bound within the galaxy\npopulation.", "positive": "The nature of massive black hole binary candidates: II. Spectral energy\n distribution atlas: Recoiling supermassive black holes (SMBHs) are considered one plausible\nphysical mechanism to explain high velocity shifts between narrow and broad\nemission lines sometimes observed in quasar spectra. If the sphere of influence\nof the recoiling SMBH is such that only the accretion disc is bound, the dusty\ntorus would be left behind, hence the SED should then present distinctive\nfeatures (i.e. a mid-infrared deficit). Here we present results from fitting\nthe Spectral Energy Distributions (SEDs) of 32 Type-1 AGN with high velocity\nshifts between broad and narrow lines. The aim is to find peculiar properties\nin the multi-wavelength SEDs of such objects by comparing their physical\nparameters (torus and disc luminosity, intrinsic reddening, and size of the\n12$\\mu$m emitter) with those estimated from a control sample of $\\sim1000$\n\\emph{typical} quasars selected from the Sloan Digital Sky Survey in the same\nredshift range. We find that all sources, with the possible exception of\nJ1154+0134, analysed here present a significant amount of 12~$\\mu$m emission.\nThis is in contrast with a scenario of a SMBH displaced from the center of the\ngalaxy, as expected for an undergoing recoil event." }, { "anchor": "Constraining the Initial Mass function in the Epoch of Reionization from\n Astrophysical and Cosmological data: [abridged] We aim to constrain the stellar initial mass function (IMF) during\nthe epoch of reionization. To this purpose, we build up a semi-empirical model\nfor the reionization history of the Universe, based on various ingredients: the\nlatest determination of the UV galaxy luminosity function from JWST out to\nredshift $z\\lesssim 12$; data-inferred and simulation-driven assumptions on the\nredshift-dependent escape fraction of ionizing photons from primordial\ngalaxies; a simple yet flexible parameterization of the IMF $\\phi(m_\\star)\\sim\nm_\\star^\\xi\\, e^{-m_{\\star,\\rm c}/m_\\star}$ in terms of a high-mass end slope\n$\\xi<0$ and of a characteristic mass $m_{\\star,\\rm c}$ below which a flattening\nor a bending sets in; the PARSEC stellar evolution code to compute the UV and\nionizing emission from different star's masses as a function of age and\nmetallicity; a few physical constraints related to stellar and galaxy formation\nin faint galaxies at the reionization redshifts. We compare our model outcomes\nwith the reionization observables from different astrophysical and cosmological\nprobes, and perform Bayesian inference on the IMF parameters. We find that the\nIMF slope $\\xi$ is within the range from $-2.8$ to $-2.3$, while appreciably\nflatter slopes are excluded at great significance. However, the bestfit value\nof the IMF characteristic mass $m_{\\star,\\rm c}\\sim$ a few $M_\\odot$ implies a\nsuppression in the formation of small stellar masses, at variance with the IMF\nin the local Universe; this may be induced by the thermal background $\\sim\n20-30$ K provided by CMB photons at the reionization redshifts. Finally, we\ninvestigate the implications of our reconstructed IMF on the recent JWST\ndetections of massive galaxies at and beyond the reionization epoch, showing\nthat any putative tension with the standard cosmological framework is\nsubstantially alleviated.", "positive": "Prospects for observing supermassive black hole binaries with the\n space-ground interferometer: A list of candidates for \\textit{supermassive binary black holes} (SMBBHs),\ncompiled from available data on the variability in the optical range and the\nshape of the emission spectrum, is analysed. An artificial neural network is\nconstructed to estimate the radiation flux at 240~GHz. For those candidate\nSMBBH for which the network building procedure was feasible, the criterion of\nthe possibility of observing the source at the \\textit{Millimetron Space\nObservatory} (MSO) was tested. The result is presented as a table of 17\ncandidate SMBBHs. Confirmation (or refutation) of the duality of these objects\nby means of observational data which could be commited on a space-ground\ninterferometer with parameters similar to those of the MSO will be an important\nmilestone in the development of the theory of galaxy formation." }, { "anchor": "On dynamical friction in a gaseous medium with a boundary: Dynamical friction arises from the interaction of a perturber and the\ngravitational wake it excites in the ambient medium. We study the effects of\nthe presence of a boundary on dynamical friction by studying analytically the\ninteraction of perturber with uniform rectilinear motion in a uniform\nhomogeneous medium with a reflecting planar boundary. Wake reflection at a\nmedium's boundary may occur at the edges of truncated disks perturbed by\nplanetary or stellar companions as well as in numerical simulations of\nplanet-disk interaction with no-outflow boundary conditions. In this paper, we\nshow that the presence of the boundary modifies the behaviour of dynamical\nfriction significantly. We find that perturbers are invariably pushed away from\nthe boundary and reach a terminal subsonic velocity near Mach 0.37 regardless\nof initial velocity. Dynamical friction may even be reversed for Mach numbers\nless than 0.37 thereby accelerating instead of decelerating the perturber.\nPerturbers moving parallel to the boundary feel additional friction orthogonal\nto the direction of motion that is much stronger than the standard friction\nalong the direction of motion. These results indicate that the common use of\nthe standard Chandrasekhar formula as a short hand estimate of dynamical\nfriction may be inadequate as observed in various numerical simulations.", "positive": "HST Imaging of Dust Structures and Stars in the Ram Pressure Stripped\n Virgo Spirals NGC 4402 and NGC 4522: Stripped from the Outside In with Dense\n Cloud Decoupling: We describe and constrain the origins of ISM structures likely created by\nongoing ICM ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and\nNGC 4402, using HST BVI images of dust extinction and stars, as well as\nsupplementary HI, Halpha, and radio continuum images. This is the\nhighest-resolution study to date of the physical processes that occur during an\nICM-ISM ram pressure stripping interaction, ram pressure stripping's effects on\nthe multi-phase, multi-density ISM, and the formation and evolution of\nram-pressure-stripped tails. In dust extinction, we view the leading side of\nNGC 4402 and the trailing side of NGC 4522; we see distinct types of features\nin both galaxies. NGC 4522 has experienced stronger, more recent pressure and\nhas the jellyfish morphology characteristic of some ram pressure stripped\ngalaxies. Its stripped tail extends up from the disk plane in continuous\nupturns of dust and stars curving ~2 kpc above the disk plane. A kinematically\nand morphologically distinct extraplanar arm of young, blue stars and ISM\nextends above a mostly-stripped portion of the disk, and between it and the\ndisk plane are decoupled dust clouds. NGC 4402 contains long dust ridges,\nsuggesting that large parts of the ISM are being pushed out at once. Both\ngalaxies contain long ridges of polarized radio continuum emission indicating\nthe presence of large-scale ordered magnetic fields. We propose that magnetic\nfields could bind together gas of different densities, causing nearby gas of\ndifferent densities to be stripped at the same rate and creating the large,\ncoherent dust ridges and upturns. A number of factors that play roles in\ndetermining what types of structures form as a result of ram pressure: ram\npressure strength and history, the location within the galaxy relative to the\nleading side, and pre-existing substructure in the ISM that may be bound\ntogether by magnetic fields." }, { "anchor": "Uncovering a Massive z~7.7 Galaxy Hosting a Heavily Obscured Radio-Loud\n QSO Candidate in COSMOS-Web: In this letter, we report the discovery of the highest redshift, heavily\nobscured, radio-loud AGN candidate selected using JWST NIRCam/MIRI, mid-IR,\nsub-mm, and radio imaging in the COSMOS-Web field. Using multi-frequency radio\nobservations and mid-IR photometry, we identify a powerful, radio-loud (RL),\ngrowing supermassive black hole (SMBH) with significant spectral steepening of\nthe radio SED ($f_{1.28 \\mathrm{GHz}} \\sim 2$ mJy, $q_{24\\mu m} = -1.1$,\n$\\alpha_{1.28-3\\mathrm{GHz}}=-1.2$, $\\Delta \\alpha = -0.4$). In conjunction\nwith ALMA, deep ground-based observations, ancillary space-based data, and the\nunprecedented resolution and sensitivity of JWST, we find no evidence of AGN\ncontribution to the UV/optical/NIR data and thus infer heavy amounts of\nobscuration (N$_{\\mathrm{H}} > 10^{23}$ cm$^{-2}$). Using the wealth of deep UV\nto sub-mm photometric data, we report a singular solution photo-z of\n$z_\\mathrm{phot}$ = 7.7$^{+0.4}_{-0.3}$ and estimate an extremely massive\nhost-galaxy ($\\log M_{\\star} = 11.4 -12\\,\\mathrm{M}_{\\odot}$) hosting a\npowerful, growing SMBH (L$_{\\mathrm{Bol}} = 4-12 \\times 10^{46}$ erg s$^{-1}$).\nThis source represents the furthest known obscured RL AGN candidate, and its\nlevel of obscuration aligns with the most representative but observationally\nscarce population of AGN at these epochs.", "positive": "The HST Large Programme on NGC 6752. I. Serendipitous discovery of a\n dwarf Galaxy in background: As part of a large Hubble Space Telescope investigation aiming at reaching\nthe faintest stars in the Galactic globular cluster NGC 6752, an ACS/WFC field\nwas the subject of deep optical observations reaching magnitudes as faint as\nV~30. In this field we report the discovery of Bedin I a dwarf spheroidal\ngalaxy too faint and too close to the core of NGC 6752 for detection in earlier\nsurveys. As it is of broad interest to complete the census of galaxies in the\nlocal Universe, in this Letter we provide the position of this new object along\nwith preliminary assessments of its main param eters. Assuming the same\nreddening as for NGC 6752, we estimate a distance modulus of (m-M)_0 =\n29.70+/-0.13 from the observed red giant branch, i.e., 8.7 (+0.5 -0.7) Mpc, and\nsize of ~840x340pc, about 1/5 the size of the LMC. A comparison of the observed\ncolour-magnitude diagram with synthetic counterparts that account for the\ngalaxy distance modulus, reddening and photometric errors, suggests the\npresence of an old (~13Gyr) and metal poor ([Fe/H]~-1.3) population. This\nobject is most likely a relatively isolated satellite dwarf spheroidal galaxy\nof the nearby great spiral NGC 6744, or potentially the most distant isolated\ndwarf spheroidal known with a secure distance." }, { "anchor": "Spatially Resolved Spitzer-IRS Spectral Maps of the Superwind in M82: We have mapped the superwind/halo region of the nearby starburst galaxy M82\nin the mid-infrared with $Spitzer-IRS$. The spectral regions covered include\nthe H$_2 S(1)-S(3)$, [NeII], [NeIII] emission lines and PAH features. We\nestimate the total warm H$_2$ mass and the kinetic energy of the outflowing\nwarm molecular gas to be between $M_{warm}\\sim5-17\\times10^6$ M$_{\\odot}$ and\n$E_{K}\\sim6-20\\times10^{53}$ erg. Using the ratios of the 6.2, 7.7 and 11.3\nmicron PAH features in the IRS spectra, we are able to estimate the average\nsize and ionization state of the small grains in the superwind. There are large\nvariations in the PAH flux ratios throughout the outflow. The 11.3/7.7 and the\n6.2/7.7 PAH ratios both vary by more than a factor of five across the wind\nregion. The Northern part of the wind has a significant population of PAH's\nwith smaller 6.2/7.7 ratios than either the starburst disk or the Southern\nwind, indicating that on average, PAH emitters are larger and more ionized. The\nwarm molecular gas to PAH flux ratios (H$_2/PAH$) are enhanced in the outflow\nby factors of 10-100 as compared to the starburst disk. This enhancement in the\nH$_2/PAH$ ratio does not seem to follow the ionization of the atomic gas (as\nmeasured with the [NeIII]/[NeII] line flux ratio) in the outflow. This suggests\nthat much of the warm H$_2$ in the outflow is excited by shocks. The observed\nH$_2$ line intensities can be reproduced with low velocity shocks ($v < 40$ km\ns$^{-1}$) driven into moderately dense molecular gas ($10^2 24.2$ and log($N_{\\rm{H}}/\\rm{cm}^2)>24.1$,\nrespectively. The nature of the nuclear activity in NGC 4178 remains\ninconclusive; it is plausible that the [Ne V] traces a period of higher\nactivity in the past, but that the AGN is relatively quiescent now. The\nnon-detection in J0851+3926 and multiwavelength properties are consistent with\nthe AGN being heavily obscured.", "positive": "The large- and small-scale CaII K structure of the Milky Way from\n observations of Galactic and Magellanic sightlines: Aims: By utilising spectra of early-type stellar probes of known distances in\nthe same region of the sky, the large and small-scale (pc) structure of the\nGalactic ISM can be investigated. This paper determines the variation in line\nstrength of CaII at 3933.661 A, as a function of probe separation for a sample\nof stars, including many sightlines in the Magellanic Clouds. Methods:\nFLAMES-GIRAFFE data taken with the VLT towards early-type stars in 3 Galactic &\n4 Magellanic open clusters in CaII are used to obtain the velocity, EW, column\ndensity and line width of IS Galactic Ca for a total of 657 stars, of which 443\nare Magellanic sightlines. In each cluster there are 43-110 stars observed.\nAdditionally, FEROS and UVES CaII & NaI spectra of 21 Galactic & 154 Magellanic\nearly-type stars are presented and combined with data from the literature to\nstudy the Ca column density/parallax relationship. Results: For the four\nMagellanic clusters studied with FLAMES, the strength of the Galactic IS CaII K\nEW over transverse scales from 0.05-9 pc is found to vary by factors of\n1.8-3.0, corresponding to column density variations of 0.3-0.5 dex in the\noptically-thin approximation. Using FLAMES, FEROS and UVES archive spectra, the\nmin and max reduced EW for MW gas is found to lie in the range 35-125 mA &\n30-160 mA for CaII K and NaI D, respectively. The range is consistent with a\nsimple model of the ISM published by van Loon et al. (2009) consisting of\nspherical cloudlets of filling factor 0.3, although other geometries are not\nruled out. Finally, the derived functional form for parallax and CaII column\ndensity is found to be pi(mas)=1/(2.39e-13 x N(CaII)(cm-2)+0.11). Our derived\nparallax is 25 per cent lower than predicted by Megier et al. (2009) at a\ndistance of 100 pc and 15% lower at a distance of 200 pc, reflecting\ninhomogeneity in the CaII distribution in the different sightlines studied." }, { "anchor": "Investigating the Relativistic Motion of the Stars Near the Supermassive\n Black Hole in the Galactic Center: The S-star cluster in the Galactic center allows us to study the physics\nclose to a supermassive black hole, including distinctive dynamical tests of\ngeneral relativity. Our best estimates for the mass of and the distance to Sgr\nA* using the three stars with the shortest period (S2, S38, and S55/S0-102) and\nNewtonian models are M_BH = (4.15+- 0.13 +- 0.57) x 10^6 M_sun and R_0 = 8.19\n+- 0.11 +- 0.34 kpc. Additionally, we aim at a new and practical method to\ninvestigate the relativistic orbits of stars in the gravitational field near\nSgr A*. We use a first-order post- Newtonian approximation to calculate the\nstellar orbits with a broad range of periapse distance r_p. We present a method\nthat employs the changes in orbital elements derived from elliptical fits to\ndifferent sections of the orbit. These changes are correlated with the\nrelativistic parameter defined as {\\Upsilon} = r_s/r_p (with r_s being the\nSchwarzschild radius) and can be used to derive {\\Upsilon} from observational\ndata. For S2 we find a value of {\\Upsilon} = 0.00088 +- 0.00080, which is\nconsistent, within the uncertainty, with the expected value of {\\Upsilon} =\n0.00065 derived from MBH and the orbit of S2. We argue that the derived\nquantity is unlikely to be dominated by perturbing influences such as noise on\nthe derived stellar positions, field rotation, and drifts in black hole mass.", "positive": "Resonant Orbits and the High Velocity Peaks Towards the Bulge: We extract the resonant orbits from an N-body bar that is a good\nrepresentation of the Milky Way, using the method recently introduced by Molloy\net al. (2015). By decomposing the bar into its constituent orbit families, we\nshow that they are intimately connected to the boxy-peanut shape of the\ndensity. We highlight the imprint due solely to resonant orbits on the\nkinematic landscape towards the Galactic centre. The resonant orbits are shown\nto have distinct kinematic features and may be used to explain the cold\nvelocity peak seen in the APOGEE commissioning data (Nidever at al., 2012). We\nshow that high velocity peaks are a natural consequence of the motions of stars\nin the 2:1 orbit family and that stars on other higher order resonances can\ncontribute to the peaks. The locations of the peaks vary with bar angle and,\nwith the tacit assumption that the observed peaks are due to the 2:1 family, we\nfind that the locations of the high velocity peaks correspond to bar angles in\nthe range 10 < theta_bar < 25 (deg). However, some important questions about\nthe nature of the peaks remain, such as their apparent absence in other surveys\nof the Bulge and the deviations from symmetry between equivalent fields in the\nnorth and south. We show that the absence of a peak in surveys at higher\nlatitudes is likely due to the combination of a less prominent peak and a lower\nnumber density of bar supporting orbits at these latitudes." }, { "anchor": "The Utility of Lyman-alpha Emission Lines as a Probe of Interactions\n between High Redshift Galaxies and their Environments: The Lyman-alpha emission line is the strongest feature in the spectrum of\nmost high redshift galaxies, and is typically observed as being highly\nasymmetric due to galactic outflows. Quantifying this asymmetry is challenging.\nHere, we explore how measurements of one parameterisation, Lyman-alpha\nskewness, are affected by instrumental resolution and detection signal-to-noise\nand thus whether this can be extended throughout the archive. We model these\neffects through simulated lines and apply our derived corrections to existing\narchival data sets (including sources observed with FORS2 and DEIMOS) to\nreconstruct the intrinsic line emission parameters. We find a large uncertainty\nin parameter reconstruction at low resolutions (R<3000) and high skew values,\nas well as substantial random errors resulting from the masking of sky lines.\nWe suggest that interpretations of spectral line asymmetry should be made with\ncaution, while a simpler parametrization, like B/R (blue-red flux asymmetry),\nis likely to yield more robust results. We see a possible weak trend in\nvelocity width with mass, although there is no evidence in the data for a\nreliable correlation of skew with galaxy mass, star formation rate or age at\nz=4-5. Using our results, we investigate the possibilities of recovering\nemission line asymmetry with current and future instruments.", "positive": "Role of magnetic fields in ram pressure stripped galaxies: Ram-pressure stripping is a crucial evolutionary driver for cluster galaxies\nand jellyfish galaxies, characterized by very extended tails of stripped gas,\nare the most striking examples of it in action. Recently, those extended tails\nare found to show on-going star formation raising the question how the\nstripped, cold gas can survive long enough to form new stars outside the\nstellar disk. In this work, we summarize the most recent results achieved\nwithin the GASP collaboration to provide a holistic explanation for this\nphenomenon. We focus on two textbook examples of jellyfish galaxies, JO206 and\nJW100 for which, via multi-wavelength observations from radio to X-ray and\nnumerical simulations, we have explored the different gas phases (neutral,\nmolecular, diffuse-ionized, and hot). Based on additional multi-phase gas\nstudies we now propose a scenario of stripped tail evolution including all\nphases that is driven by a magnetic draping sheath, where the intracluster\nturbulent magnetized plasma condenses onto the galaxy disk and tail and\nproduces a magnetized interface that protects the stripped galaxy tail gas from\nevaporation. In such a scenario, the accreted environmental plasma can cool\ndown and eventually join the tail gas, hence providing additional gas to form\nstars. The implications of our findings can shed light on the more general\nscenario of draping, condensation, and cooling of hot gas surrounding cold\nclouds that is fundamental in many astrophysical phenomena." }, { "anchor": "Dust Rotational Dynamics in C-shocks: Rotational Disruption of\n Nanoparticles by Stochastic Mechanical Torques and Spinning Dust Emission: Polycyclic aromatic hydrocarbons (PAHs) and nanoparticles are expected to\nplay an important role in many astrophysical processes due to its dominant\nsurface area, including gas heating, chemistry, star formation , and anomalous\nmicrowave emission. In dense magnetized molecular clouds where C-shocks are\npresent, PAHs and nanoparticles are widely believed to originate from grain\nshattering due to grain-grain collisions. The remaining question is whether\nthese nanoparticles can survive in the dense and hot shocked regions, and how\nto constrain their size and abundance with observations. In this paper, we\npresent a new mechanism to destroy nanoparticles in C-shocks based on\ncentrifugal stress within rapidly spinning nanoparticles spun-up by stochastic\natomic bombardment, which is termed rotational disruption. We find that, due to\nsupersonic neutral gas-charged grain drift in C-shocks, nanoparticles can be\nspun-up to suprathermal rotation by stochastic torques exerted by supersonic\nneutral flow. The resulting centrifugal stress within suprathermally rotating\nnanoparticles can exceed the maximum tensile strength of grain material\n($S_{\\max}$), resulting in rapid disruption of nanoparticles smaller than\n$a\\sim 1$ nm for $S_{\\max}\\sim 10^{9}\\erg\\cm^{-3}$. The proposed disruption\nmechanism is shown to be more efficient than thermal sputtering in controlling\nthe lower cutoff of grain size distribution in C-shocks. We model microwave\nemission from spinning nanoparticles in C-shocks subject to supersonic neutral\ndrift and rotational disruption. We find that suprathermally rotating\nnanoparticles can emit strong microwave radiation, and both peak flux and peak\nfrequency increase with increasing the shock velocity. We suggest spinning dust\nas a new method to constrain nanoparticles and trace shock velocities in dense,\nshocked regions.", "positive": "XMM-Newton Observations of Two Archival X-ray Weak Type 1 Quasars:\n Obscuration Induced X-ray Weakness and Variability: We report \\hbox{XMM-Newton} observations of two examples of an unclassified\ntype of \\hbox{X-ray} weak quasars from the \\citet{2020ApJ...900..141P} survey\nof \\hbox{X-ray} weak quasars in the Chandra archive, SDSS J083116.62+321329.6\nat $z=1.797$ and SDSS J142339.87+042041.1 at $z=1.702$. They do not belong to\nthe known populations of \\hbox{X-ray} weak quasars that show broad absorption\nlines, weak ultraviolet (UV) broad emission lines, or red optical/UV continua.\nInstead, they display typical quasar UV spectra and spectral energy\ndistributions. In the \\hbox{XMM-Newton} observations, both quasars show nominal\nlevels of \\hbox{X-ray} emission with typical quasar \\hbox{X-ray} spectral\nshapes (\\hbox{power-law} photon indices of $1.99^{+0.27}_{-0.23}$ and\n$1.86^{+0.15}_{-0.14}$), displaying strong \\hbox{X-ray} variability compared to\nthe archival Chandra data (variability factors of $4.0^{+1.6}_{-1.4}$ and\n$9.0^{+7.4}_{-3.8}$ in terms of the 2 keV flux density). Simultaneous optical\n(rest-frame UV) spectra indicate no strong variability compared to the archival\nspectra. Long-term optical/UV and infrared light curves do not show any\nsubstantial variability either. We consider that the \\hbox{X-ray} weakness\nobserved in the Chandra data is due to \\hbox{X-ray} obscuration from a\nsmall-scale dust-free absorber, likely related to accretion-disk winds. Such\n\\hbox{X-ray} weak/absorbed states are probably rare in typical quasars, and\nthus both targets recovered to \\hbox{X-ray} nominal-strength states in the\n\\hbox{XMM-Newton} observations." }, { "anchor": "Peekaboo: the extremely metal poor dwarf galaxy HIPASS J1131-31: The dwarf irregular galaxy HIPASS J1131-31 was discovered as a source of HI\nemission at low redshift in such close proximity of a bright star that we call\nit Peekaboo. The galaxy resolves into stars in images with Hubble Space\nTelescope, leading to a distance estimate of 6.8+-0.7 Mpc. Spectral optical\nobservations with the Southern African Large Telescope reveal HIPASS J1131-31\nto be one of the most extremely metal-poor galaxies known with the gas-phase\noxygen abundance 12+log(O/H) = 6.99+-0.16 dex via the direct [OIII] 4363 line\nmethod and 6.87+-0.07 dex from the two strong line empirical methods. The red\ngiant branch of the system is tenuous compared with the prominence of the\nfeatures of young populations in the color-magnitude diagram, inviting\nspeculation that star formation in the galaxy only began in the last few Gyr.", "positive": "Galaxy stellar mass assembly: the difficulty matching observations and\n semi-analytical predictions: Semi-analytical models (SAMs) are currently the best way to understand the\nformation of galaxies within the cosmic dark-matter structures. While they\nfairly well reproduce the local stellar mass functions, correlation functions\nand luminosity functions, they fail to match observations at high redshift (z >\n3) in most cases, particularly in the low-mass range. The inconsistency between\nmodels and observations indicates that the history of gas accretion in\ngalaxies, within their host dark-matter halo, and the transformation of gas\ninto stars, are not well followed. Hereafter, we briefly present a new version\nof the GalICS semi-analytical model. We explore the impacts of classical\nmechanisms, such as supernova feedback or photoionization, on the evolution of\nthe stellar mass assembly. Even with a strong efficiency, these two processes\ncannot explain the observed stellar mass function and star formation rate\ndistribution and some other relations. We thus introduce an ad-hoc modification\nof the standard paradigm, based on the presence of a \\textit{no-star-forming}\ngas component, and a concentration of the star-forming gas in galaxy discs. The\nmain idea behind the existence of the no-star-forming gas reservoir is that\nonly a fraction of the total gas mass in a galaxy is available to form stars.\nThe reservoir generates a delay between the accretion of the gas and the star\nformation process. This new model is in much better agreement with the\nobservations of the stellar mass function in the low-mass range than the\nprevious models, and agrees quite well with a large set of observations,\nincluding the redshift evolution of the specific star formation rate. However,\nit predicts a large fraction of no-star-forming baryonic gas, potentially\nlarger than observed, even if its nature has still to be examined in the\ncontext of the missing baryon problem." }, { "anchor": "Rejuvenation in $z\\sim0.8$ quiescent galaxies in LEGA-C: We use reconstructed star-formation histories (SFHs) of quiescent galaxies at\n$z=0.6-1$ in the LEGA-C survey to identify secondary star-formation episodes\nthat, after an initial period of quiescence, moved the galaxies back to the\nstar-forming main sequence (blue cloud). $16\\pm3$\\% of the $z\\sim0.8$ quiescent\npopulation has experienced such rejuvenation events in the redshift range\n$0.710$~GHz) source population; they under-predict the number of\nobserved sources by a factor of two below $S_{18~\\rm GHz} = 10$ mJy and fail to\nreproduce the observed spectral index distribution. We suggest that this is\nbecause the faint radio galaxies are not modelled correctly in the simulations\nand show that by adding a flat-spectrum core component to the FRI sources in\nthe SKA Simulated Skies, the observed 15-GHz source counts can be reproduced.\nWe find that the observations are best matched by assuming that the fraction of\nthe total 1.4-GHz flux density which originates from the core varies with\n1.4-GHz luminosity; sources with 1.4-GHz luminosities $< 10^{25} \\rm W \\,\nHz^{-1}$ require a core fraction $\\sim 0.3$, while the more luminous sources\nrequire a much smaller core fraction of $5 \\times 10^{-4}$. The low luminosity\nFRI sources with high core fractions which were not included in the original\nsimulation may be equivalent to the compact `FR0' sources found in recent\nstudies." }, { "anchor": "The PAU Survey: a new constraint on galaxy formation models using the\n observed colour redshift relation: We use the GALFORM semi-analytical galaxy formation model implemented in the\nPlanck Millennium N-body simulation to build a mock galaxy catalogue on an\nobserver's past lightcone. The mass resolution of this N-body simulation is\nalmost an order of magnitude better than in previous simulations used for this\npurpose, allowing us to probe fainter galaxies and hence build a more complete\nmock catalogue at low redshifts. The high time cadence of the simulation\noutputs allows us to make improved calculations of galaxy properties and\npositions in the mock. We test the predictions of the mock against the Physics\nof the Accelerating Universe Survey, a narrow band imaging survey with highly\naccurate and precise photometric redshifts, which probes the galaxy population\nover a lookback time of 8 billion years. We compare the model against the\nobserved number counts, redshift distribution and evolution of the observed\ncolours and find good agreement; these statistics avoid the need for\nmodel-dependent processing of the observations. The model produces red and blue\npopulations that have similar median colours to the observations. However, the\nbimodality of galaxy colours in the model is stronger than in the observations.\nThis bimodality is reduced on including a simple model for errors in the\nGALFORM photometry. We examine how the model predictions for the observed\ngalaxy colours change when perturbing key model parameters. This exercise shows\nthat the median colours and relative abundance of red and blue galaxies provide\nconstraints on the strength of the feedback driven by supernovae used in the\nmodel.", "positive": "Adaptive optics observations of the gravitationally lensed quasar SDSS\n J1405+0959: We present the result of Subaru Telescope multi-band adaptive optics\nobservations of the complex gravitationally lensed quasar SDSS J1405+0959,\nwhich is produced by two lensing galaxies. These observations reveal\ndramatically enhanced morphological detail, leading to the discovery of an\nadditional object 0. 26'' from the secondary lensing galaxy, as well as three\ncollinear clumps located in between the two lensing galaxies. The new object is\nlikely to be the third quasar image, although the possibility that it is a\ngalaxy cannot be entirely excluded. If confirmed via future observations, it\nwould be the first three image lensed quasar produced by two galaxy lenses. In\neither case, we show based on gravitational lensing models and photometric\nredshift that the collinear clumps represent merging images of a portion of the\nquasar host galaxy, with a magnification factor of 15 - 20, depending on the\nmodel." }, { "anchor": "Quiescent low-mass galaxies observed by JWST in the Epoch of\n Reionization: The surprising JWST discovery of a quiescent, low-mass ($M_\\star=10^{8.7} \\rm\nM_\\odot$) galaxy at redshift $z=7.3$ (JADES-GS-z7-01-QU) represents a unique\nopportunity to study the imprint of feedback processes on early galaxy\nevolution. We build a sample of 130 low-mass ($M_\\star\\lesssim 10^{9.5} \\rm\nM_\\odot$) galaxies from the SERRA cosmological zoom-in simulations, which show\na feedback-regulated, bursty star formation history (SFH). The fraction of time\nspent in an active phase increases with the stellar mass from $f_{duty}\\approx\n0.6$ at $M_\\star\\approx 10^{7.5} \\rm M_\\odot$ to $\\approx 0.99$ at $M_\\star\\geq\n10^{9} \\rm M_\\odot$, and it is in agreement with the value $f_{duty}\\approx\n0.75$ estimated for JADES-GS-z7-01-QU. On average, 30% of the galaxies are\nquiescent in the range $6 < z < 8.4$; they become the dominant population at\n$M_\\star\\lesssim 10^{8.3} \\rm M_\\odot$. However, none of these quiescent\nsystems matches the Spectral Energy Distribution of JADES-GS-z7-01-QU, unless\ntheir SFH is artificially truncated a few Myr after the main star formation\npeak. As supernova feedback can only act on a longer timescale ($\\gtrsim 30 \\rm\n\\, Myr$), this implies that the observed abrupt quenching must be caused by a\nfaster physical mechanism, such as radiation-driven winds.", "positive": "A possible formation scenario for dwarf spheroidal galaxies - III.\n Adding star formation histories to the fiducial model: Dwarf spheroidal galaxies are regarded as the basic building blocks in the\nformation of larger galaxies and are believed to be the most dark matter\ndominated systems known in the Universe. There are several models that attempt\nto explain their formation and evolution, but they have problems to model the\nformation of isolated dwarf spheroidal galaxies. Here, we will explain a\npossible formation scenario in which star clusters form inside the dark matter\nhalo of a dwarf spheroidal galaxy. Those star clusters suffer from low star\nformation efficiency and dissolve while orbiting inside the dark matter halo.\nThereby, they build the faint luminous components that we observe in dwarf\nspheroidal galaxies. In this paper we study this model by adding different star\nformation histories to the simulations to compare the results with our previous\nwork and observational data to show that we can explain the formation of dwarf\nspheroidal galaxies." }, { "anchor": "JINGLE -- IV. Dust, HI gas and metal scaling laws in the local Universe: Scaling laws of dust, HI gas and metal mass with stellar mass, specific star\nformation rate and metallicity are crucial to our understanding of the buildup\nof galaxies through their enrichment with metals and dust. In this work, we\nanalyse how the dust and metal content varies with specific gas mass\n($M_{\\text{HI}}$/$M_{\\star}$) across a diverse sample of 423 nearby galaxies.\nThe observed trends are interpreted with a set of Dust and Element evolUtion\nmodelS (DEUS) - incluidng stellar dust production, grain growth, and dust\ndestruction - within a Bayesian framework to enable a rigorous search of the\nmulti-dimensional parameter space. We find that these scaling laws for galaxies\nwith $-1.0\\lesssim \\log M_{\\text{HI}}$/$M_{\\star}\\lesssim0$ can be reproduced\nusing closed-box models with high fractions (37-89$\\%$) of supernova dust\nsurviving a reverse shock, relatively low grain growth efficiencies\n($\\epsilon$=30-40), and long dus lifetimes (1-2\\,Gyr). The models have\npresent-day dust masses with similar contributions from stellar sources\n(50-80\\,$\\%$) and grain growth (20-50\\,$\\%$). Over the entire lifetime of these\ngalaxies, the contribution from stardust ($>$90\\,$\\%$) outweighs the fraction\nof dust grown in the interstellar medium ($<$10$\\%$). Our results provide an\nalternative for the chemical evolution models that require extremely low\nsupernova dust production efficiencies and short grain growth timescales to\nreproduce local scaling laws, and could help solving the conundrum on whether\nor not grains can grow efficiently in the interstellar medium.", "positive": "The impact of two massive early accretion events in a Milky Way-like\n galaxy: repercussions for the buildup of the stellar disc and halo: We identify and characterise a Milky Way-like realisation from the Auriga\nsimulations with two consecutive massive mergers $\\sim2\\,$Gyr apart at high\nredshift, comparable to the reported Kraken and Gaia-Sausage-Enceladus. The\nKraken-like merger ($z=1.6$, $M_{\\rm Tot} = 8\\times10^{10}\\,$M$_{\\odot}$) is\ngas-rich, deposits most of its mass in the inner $10\\,$kpc, and is largely\nisotropic. The Sausage-like merger ($z=1.14$, $M_{\\rm Tot} =\n1\\times10^{11}\\,$M$_{\\odot}$) leaves a more extended mass distribution at\nhigher energies, and has a radially anisotropic distribution. For the higher\nredshift merger, the stellar mass ratio of the satellite to host galaxy is 1:3.\nAs a result, the chemistry of the remnant is indistinguishable from\ncontemporaneous in-situ populations, making it challenging to identify this\ncomponent through chemical abundances. This naturally explains why all\nabundance patterns attributed so far to Kraken are in fact fully consistent\nwith the metal-poor in-situ so-called Aurora population and thick disc.\nHowever, our model makes a falsifiable prediction: if the Milky Way underwent a\ngas-rich double merger at high redshift, then this should be imprinted on its\nstar formation history with bursts about $\\sim2\\,$Gyrs apart. This may offer\nconstraining power on the highest-redshift major mergers." }, { "anchor": "MUSE observations of the giant low surface brightness galaxy Malin 1:\n Numerous HII regions, star formation rate, metallicity, and dust attenuation: Giant low-surface brightness (GLSB) galaxies are an extreme class of objects\nwith very faint and extended gas-rich disks. Malin 1 is the largest GLSB galaxy\nknown to date, but its formation is still poorly understood. We use VLT/MUSE\nIFU spectroscopic observations of Malin 1 to reveal, for the first time, the\npresence of H$\\alpha$ emission distributed across numerous regions along its\ndisk, up to radial distances of $\\sim$100 kpc. We made an estimate of the dust\nattenuation using the Balmer decrement and found that Malin 1 has a mean\nH$\\alpha$ attenuation of 0.36 mag. We observe a steep decline in the star\nformation rate surface density ($\\Sigma_{\\rm SFR}$) within the inner 20 kpc,\nfollowed by a shallow decline in the extended disk. Similarly, the gas phase\nmetallicity we estimated shows a steep gradient in the inner 20 kpc, followed\nby a flattening of the metallicity in the extended disk with a relatively high\nvalue of $\\sim$0.6 $Z_{\\odot}$. We found that the normalized abundance gradient\nof the inner disk is similar to values found in normal galaxies but with an\nextreme value in the extended disk. A comparison of the star formation rate\nsurface density and gas surface density shows that, unlike normal disk galaxies\nor other LSBs, Malin 1 exhibits a very low star formation efficiency. Owing to\nthe detection of emission lines over a large part of the disk of Malin 1, this\nwork sheds light on the star formation processes in this unique galaxy,\nhighlighting its extended star-forming disk, dust attenuation, almost flat\nmetallicity distribution in the outer disk, and exceptionally low\nstar-formation efficiency. Our findings contribute to a more detailed\nunderstanding of the formation of the giant disk of Malin 1 and also constrain\npossible proposed scenarios on the nature of GLSB galaxies in general.", "positive": "Substellar fragmentation in self-gravitating fluids with a major phase\n transition: The existence of substellar cold H2 globules in planetary nebulae and the\nmere existence of comets suggest that the physics of cold interstellar gas\nmight be much richer than usually envisioned.\n We study the case of a cold gaseous medium in ISM conditions which is subject\nto a gas-liquid/solid phase transition.\n First the equilibrium of general non-ideal fluids is studied using the virial\ntheorem and linear stability analysis. Then the non-linear dynamics is studied\nby using simulations to characterize the expected formation of solid bodies\nanalogous to comets. The simulations are run with a state of the art molecular\ndynamics code (LAMMPS). The long-range gravitational forces can be taken into\naccount with short-range molecular forces with finite limited computational\nresources by using super-molecules, provided the right scaling is followed.\n The concept of super-molecule is tested with simulations, allowing us to\ncorrectly satisfy the Jeans instability criterion for one-phase fluids. The\nsimulations show that fluids presenting a phase transition are gravitationally\nunstable as well, independent of the strength of the gravitational potential,\nproducing two distinct kinds of sub-stellar bodies, those dominated by gravity\n(\"planetoids\") and those dominated by molecular attractive force (\"comets\").\n Observations, formal analysis and computer simulations suggest the\npossibility of the formation of substellar H2 clumps in cold molecular clouds\ndue to the combination of phase transition and gravity. Fluids presenting a\nphase transition are gravitationally unstable, independent of the strength of\nthe gravitational potential. Arbitrarily small H2 clumps may form even at\nrelatively high temperatures up to 400 - 600K, according to virial analysis.\nThe combination of phase transition and gravity may be relevant for a wider\nrange of astrophysical situations, such as proto-planetary disks." }, { "anchor": "High-quality Extragalactic Legacy-field Monitoring (HELM) with DECam: High-quality Extragalactic Legacy-field Monitoring (HELM) is a long-term\nobserving program that photometrically monitors several well-studied\nextragalactic legacy fields with the Dark Energy Camera (DECam) imager on the\nCTIO 4m Blanco telescope. Since Feb 2019, HELM has been monitoring regions\nwithin COSMOS, XMM-LSS, CDF-S, S-CVZ, ELAIS-S1, and SDSS Stripe 82 with few-day\ncadences in the $(u)gri(z)$ bands, over a collective sky area of $\\sim 38$\ndeg${\\rm ^2}$. The main science goal of HELM is to provide high-quality optical\nlight curves for a large sample of active galactic nuclei (AGNs), and to build\ndecades-long time baselines when combining past and future optical light curves\nin these legacy fields. These optical images and light curves will facilitate\nthe measurements of AGN reverberation mapping lags, as well as studies of AGN\nvariability and its dependences on accretion properties. In addition, the\ntime-resolved and coadded DECam photometry will enable a broad range of science\napplications from galaxy evolution to time-domain science. We describe the\ndesign and implementation of the program and present the first data release\nthat includes source catalogs and the first $\\sim 3.5$ years of light curves\nduring 2019A--2022A.", "positive": "XookSuut a code for modeling circular and non-circular flows on 2D\n velocity maps: We present $\\texttt{XookSuut}$, a Python implementation of the\n$\\texttt{DiskFit}$ algorithm, optimized to perform robust Bayesian inference on\nparameters describing models of circular and noncircular rotation in galaxies.\n$\\texttt{XookSuut}$~surges as a Bayesian alternative for kinematic modeling of\n2D velocity maps; it implements efficient sampling methods, specifically Markov\nChain Monte Carlo (MCMC) and Nested Sampling (NS), to obtain the posteriors and\nmarginalized distributions of kinematic models including circular motions,\naxisymmetric radial flows, bisymmetric flows, and harmonic decomposition of the\nLoS~velocity. In this way, kinematic models are obtained by pure sampling\nmethods, rather than standard minimization techniques based on the $\\chi^2$.\nAll together, $\\texttt{XookSuut}$~represents a sophisticated tool for deriving\nrotational curves and to explore the error distribution and covariance between\nparameters." }, { "anchor": "Galaxies at a Cosmic-Ray Eddington Limit: Cosmic rays have been shown to be extremely important in the dynamics of\ndiffuse gas in galaxies, helping to maintain hydrostatic equilibrium, and\nserving as a regulating force in star formation. In this paper, we address the\ninfluence of cosmic rays on galaxies by re-examining the theory of a cosmic ray\nEddington limit, first proposed by Socrates et al. (2008) and elaborated upon\nby Crocker et al. (2021a) and Huang & Davis (2022). A cosmic ray Eddington\nlimit represents a maximum cosmic ray energy density above which the\ninterstellar gas cannot be in hydrostatic equilibrium, resulting in a wind. In\nthis paper, we continue to explore the idea of a cosmic ray Eddington limit by\nintroducing a general framework that accounts for the circumgalactic\nenvironment and applying it to five galaxies that we believe to be a good\nrepresentative sample of the star forming galaxy population, using different\ncosmic ray transport models to determine what gives each galaxy the best chance\nto reach this limit. We show that while an Eddington limit for cosmic rays does\nexist, for our five galaxies, the limit either falls at star formation rates\nthat are much larger or gas densities that are much lower than each galaxy's\nmeasured values. This suggests that cosmic ray pressure is not the main factor\nlimiting the luminosity of starburst galaxies.", "positive": "The C-Band All-Sky Survey (C-BASS): Template Fitting of Diffuse Galactic\n Microwave Emission in the Northern Sky: The C-Band All-Sky Survey (C-BASS) has observed the Galaxy at 4.76GHz with an\nangular resolution of $0.73^\\circ$ full-width half-maximum, and detected\nGalactic synchrotron emission with high signal-to-noise ratio over the entire\nnorthern sky ($\\delta > -15^{\\circ}$). We present the results of a spatial\ncorrelation analysis of Galactic foregrounds at mid-to-high ($b > 10^\\circ$)\nGalactic latitudes using a preliminary version of the C-BASS intensity map. We\njointly fit for synchrotron, dust, and free-free components between $20$ and\n$1000$GHz and look for differences in the Galactic synchrotron spectrum, and\nthe emissivity of anomalous microwave emission (AME) when using either the\nC-BASS map or the 408MHz all-sky map to trace synchrotron emission. We find\nmarginal evidence for a steepening ($\\left<\\Delta\\beta\\right> = -0.06\\pm0.02$)\nof the Galactic synchrotron spectrum at high frequencies resulting in a mean\nspectral index of $\\left<\\beta\\right> = -3.10\\pm0.02$ over $4.76-22.8$GHz.\nFurther, we find that the synchrotron emission can be well modelled by a single\npower-law up to a few tens of GHz. Due to this, we find that the AME emissivity\nis not sensitive to changing the synchrotron tracer from the 408MHz map to the\n4.76GHz map. We interpret this as strong evidence for the origin of AME being\nspinning dust emission." }, { "anchor": "Mapping dust in the giant molecular cloud Orion A: The Sun is located close to the Galactic mid-plane, meaning that we observe\nthe Galaxy through significant quantities of dust. Moreover, the vast majority\nof the Galaxy's stars also lie in the disc, meaning that dust has an enormous\nimpact on the massive astrometric, photometric and spectroscopic surveys of the\nGalaxy that are currently underway. To exploit the data from these surveys we\nrequire good three-dimensional maps of the Galaxy's dust. We present a new\nmethod for making such maps in which we form the best linear unbiased predictor\nof the extinction at an arbitrary point based on the extinctions for a set of\nobserved stars. This method allows us to avoid the artificial inhomogeneities\n(so-called 'fingers of God') and resolution limits that are characteristic of\nmany published dust maps. Moreover, it requires minimal assumptions about the\nstatistical properties of the interstellar medium. In fact, we require only a\nmodel of the first and second moments of the dust density field. The method is\nsuitable for use with directly measured extinctions, such as those provided by\nthe Rayleigh-Jeans colour excess method, and inferred extinctions, such as\nthose provided by hierarchical Bayesian models like StarHorse. We test our\nmethod by mapping dust in the region of the giant molecular cloud Orion A. Our\nresults indicate a foreground dust cloud at a distance of 350 pc, which has\nbeen identified in work by another author.", "positive": "East Asian VLBI Network Observations of Active Galactic Nuclei Jets:\n Imaging with KaVA+Tianma+Nanshan: The East Asian very-long-baseline interferometry (VLBI) Network (EAVN) is a\nrapidly evolving international VLBI array that is currently promoted under\njoint efforts among China, Japan, and Korea. EAVN aims at forming a joint VLBI\nNetwork by combining a large number of radio telescopes distributed over East\nAsian regions. After the combination of the Korean VLBI Network (KVN) and the\nVLBI Exploration of Radio Astrometry (VERA) into KaVA, further expansion with\nthe joint array in East Asia is actively promoted. Here we report the first\nimaging results (at 22 and 43 GHz) of bright radio sources obtained with KaVA\nconnected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China. To test\nthe EAVN imaging performance for different sources, we observed four active\ngalactic nuclei (AGN) having different brightness and morphology. As a result,\nwe confirmed that Tianma 65-m Radio Telescope (TMRT) significantly enhances the\noverall array sensitivity, a factor of 4 improvement in baseline sensitivity\nand 2 in image dynamic range compared to the case of KaVA only. The addition of\nNanshan 26-m Radio Telescope (NSRT) further doubled the east-west angular\nresolution. With the resulting high-dynamic-range, high-resolution images with\nEAVN (KaVA+TMRT+NSRT), various fine-scale structures in our targets, such as\nthe counter-jet in M87, a kink-like morphology of the 3C273 jet and the weak\nemission in other sources, are successfully detected. This demonstrates the\npowerful capability of EAVN to study AGN jets and to achieve other science\ngoals in general. Ongoing expansion of EAVN will further enhance the angular\nresolution, detection sensitivity and frequency coverage of the network." }, { "anchor": "Discovery of Five Green Pea Galaxies with Double-peaked Narrow [OIII]\n Lines: Although double-peaked narrow emission-line galaxies have been studied\nextensively in the past years, only a few are reported with the green pea\ngalaxies (GPs). Here we present our discovery of five GPs with double-peaked\nnarrow [OIII] emission lines, referred to as DPGPs, selected from the LAMOST\nand SDSS spectroscopic surveys. We find that these five DPGPs have blueshifted\nnarrow components more prominent than the redshifted components, with velocity\noffsets of [OIII]$\\lambda$5007 lines ranging from 306 to 518 $\\rm km\\, s^{-1}$\nand full widths at half maximums (FWHMs) of individual components ranging from\n263 to 441 $\\rm km\\, s^{-1}$. By analyzing the spectra and the spectral energy\ndistributions (SEDs), we find that they have larger metallicities and stellar\nmasses compared with other GPs. The H$\\alpha$ line width, emission-line\ndiagnostic, mid-infrared color, radio emission, and SED fitting provide\nevidence of the AGN activities in these DPGPs. They have the same spectral\nproperties of Type 2 quasars. Furthermore, we discuss the possible nature of\nthe double-peaked narrow emission-line profiles of these DPGPs and find that\nthey are more likely to be dual AGN. These DPGP galaxies are ideal laboratories\nfor exploring the growth mode of AGN in the extremely luminous emission-line\ngalaxies, the co-evolution between AGN and host galaxies, and the evolution of\nhigh-redshift galaxies in the early Universe.", "positive": "A study of radial self-similar non-relativistic MHD outflow models:\n parameter space exploration and application to the water fountain W43A: Outflows, spanning a wide range of dynamical properties and spatial\nextensions, have now been associated with a variety of accreting astrophysical\nobjects, from supermassive black holes at the core of active galaxies to young\nstellar objects. The role of such outflows is key to the evolution of the\nsystem that generates them, for they extract a fraction of the orbiting\nmaterial and angular momentum from the region close to the central object and\nrelease them in the surroundings. The details of the launching mechanism and\ntheir impact on the environment are fundamental to understand the evolution of\nindividual sources and the similarities between different types of\noutflow-launching systems. We solve semi-analytically the non-relativistic,\nideal, magnetohydrodynamics (MHD) equations describing outflows launched from a\nrotating disk threaded with magnetic fields using our new numerical scheme. We\npresent here a parameter study of a large sample of new solutions. We study the\ndifferent combinations of forces that lead to a successfully launched jet and\ndiscuss their global properties. We show how these solutions can be applied to\nthe outflow of the water fountain W43A for which we have observational\nconstraints on magnetic field, density and velocity of the flow at the location\nof two symmetrical water maser emitting regions." }, { "anchor": "Using dust, gas and stellar mass selected samples to probe dust sources\n and sinks in low metallicity galaxies: We combine samples of nearby galaxies with Herschel photometry selected on\ntheir dust, metal, HI, and stellar mass content, and compare these to chemical\nevolution models in order to discriminate between different dust sources. In a\ncompanion paper, we used a HI-selected sample of nearby galaxies to reveal a\nsub-sample of very gas rich (gas fraction > 80 per cent) sources with dust\nmasses significantly below predictions from simple chemical evolution models,\nand well below $M_d/M_*$ and $M_d/M_{gas}$ scaling relations seen in dust and\nstellar-selected samples of local galaxies. We use a chemical evolution model\nto explain these dust-poor, but gas-rich, sources as well as the observed star\nformation rates (SFRs) and dust-to-gas ratios. We find that (i) a delayed star\nformation history is required to model the observed SFRs; (ii) inflows and\noutflows are required to model the observed metallicities at low gas fractions;\n(iii) a reduced contribution of dust from supernovae (SNe) is needed to explain\nthe dust-poor sources with high gas fractions. These dust-poor, low stellar\nmass galaxies require a typical core-collapse SN to produce 0.01 - 0.16\n$M_{\\odot}$ of dust. To match the observed dust masses at lower gas fractions,\nsignificant grain growth is required to counteract the reduced contribution\nfrom dust in SNe and dust destruction from SN shocks. These findings are\nstatistically robust, though due to intrinsic scatter it is not always possible\nto find one single model that successfully describes all the data. We also show\nthat the dust-to-metals ratio decreases towards lower metallicity.", "positive": "Probing AGN Inner Structure with X-ray Obscured Type 1 AGN: Using the X-ray-selected active galactic nuclei (AGN) from the XMM-XXL north\nsurvey and the SDSS Baryon Oscillation Spectroscopic Survey (BOSS)\nspectroscopic follow-up of them, we compare the properties of X-ray unobscured\nand obscured broad-line AGN (BLAGN1 and BLAGN2; $N_\\textrm{H}$below and above\n$10^{21.5}$ cm$^{-2}$), including their X-ray luminosity $L_X$, black hole\nmass, Eddington ratio $\\lambda_{\\textrm{Edd}}$, optical continuum and line\nfeatures. We find that BLAGN2 have systematically larger broad line widths and\nhence apparently higher (lower) $M_{\\textrm{BH}}$ ($\\lambda_{\\textrm{Edd}}$)\nthan BLAGN1. We also find that the X-ray obscuration in BLAGN tends to coincide\nwith optical dust extinction, which is optically thinner than that in\nnarrow-line AGN (NLAGN) and likely partial-covering to the broad line region.\nAll the results can be explained in the framework of a multi-component, clumpy\ntorus model by interpreting BLAGN2 as an intermediate type between BLAGN1 and\nNLAGN in terms of an intermediate inclination angle." }, { "anchor": "Shock-induced stripping of satellite ISM/CGM in IllustrisTNG clusters at\n $z\\sim0$: Using the IllustrisTNG simulation, we study the interaction of large-scale\nshocks with the circumgalactic medium (CGM) and interstellar medium (ISM) of\nstar-forming (SF) satellite galaxies in galaxy clusters. These shocks are\nusually produced by mergers and massive accretion. Our visual inspection shows\nthat approximately half of SF satellites have encountered shocks in their host\nclusters at $z\\leq0.11$. After a satellite crosses a shock front and enters the\npostshock region, the ram pressure on it is boosted significantly. Both the CGM\nand ISM can be severely impacted, either by striping or compression. The\nstripping of the ISM is particularly important for low-mass galaxies with $\\log\n(M_{*}/M_{\\odot})<10$ and can occur even in the outskirts of galaxy clusters.\nIn comparison, satellites that do not interact with shocks lose their ISM only\nin the inner regions of clusters. About half of the ISM is stripped within\nabout 0.6 Gyr after it crosses the shock front. Our results show that\nshock-induced stripping plays an important role in quenching satellite galaxies\nin clusters.", "positive": "An AGN with an ionized gas outflow in a massive quiescent galaxy in a\n protocluster at $\\bf z=3.09$: We report the detection of an ionized gas outflow from an $X$-ray active\ngalactic nucleus (AGN) hosted in a massive quiescent galaxy in a protocluster\nat $z=3.09$ (J221737.29+001823.4). It is a type-2 QSO with broad ($W_{80}>1000$\nkm s$^{-1}$) and strong ($\\log (L_{\\rm [OIII]}$ / erg s$^{-1})\\approx43.4$) [O\n{\\footnotesize III}]$\\lambda\\lambda$4959,5007 emission lines detected by slit\nspectroscopy in three-position angles using Multi-Object Infra-Red Camera and\nSpectrograph (MOIRCS) on the Subaru telescope and the Multi-Object Spectrometer\nFor Infra-Red Exploration (MOSFIRE) on the Keck-I telescope. In the all slit\ndirections, [O {\\footnotesize III}] emission is extended to $\\sim15$ physical\nkpc and indicates a powerful outflow spreading over the host galaxy. The\ninferred ionized gas mass outflow rate is $\\rm 22\\pm3~M_{\\odot}~yr^{-1}$.\nAlthough it is a radio source, according to the line diagnostics using\nH$\\beta$, [O {\\footnotesize II}], and [O {\\footnotesize III}], photoionization\nby the central QSO is likely the dominant ionization mechanism rather than\nshocks caused by radio jets. On the other hand, the spectral energy\ndistribution of the host galaxy is well characterized as a quiescent galaxy\nthat has shut down star formation by several hundred Myr ago. Our results\nsuggest a scenario that QSOs are powered after the shut-down of the star\nformation and help to complete the quenching of massive quiescent galaxies at\nhigh redshift." }, { "anchor": "An Effective Selection Method for Low-Mass Active Black Holes and First\n Spectroscopic Identification: We present a new method to effectively select objects which may be low-mass\nactive black holes (BHs) at galaxy centers using high-cadence optical imaging\ndata, and our first spectroscopic identification of an active 2.7x10^6 Msun BH\nat z=0.164. This active BH was originally selected due to its rapid optical\nvariability, from a few hours to a day, based on Subaru Hyper Suprime-Cam~(HSC)\ng-band imaging data taken with 1-hour cadence. Broad and narrow H-alpha and\nmany other emission lines are detected in our optical spectra taken with Subaru\nFOCAS, and the BH mass is measured via the broad H-alpha emission line width\n(1,880 km s^{-1}) and luminosity (4.2x10^{40} erg s^{-1}) after careful\ncorrection for the atmospheric absorption around 7,580-7,720A. We measure the\nEddington ratio to be as low as 0.05, considerably smaller than those in a\nprevious SDSS sample with similar BH mass and redshift, which indicates one of\nthe strong potentials of our Subaru survey. The g-r color and morphology of the\nextended component indicate that the host galaxy is a star-forming galaxy. We\nalso show effectiveness of our variability selection for low-mass active BHs.", "positive": "First lensed quasar systems from the VST-ATLAS survey: one quad, two\n doubles and two pairs of lensless twins: We have analyzed images from the VST ATLAS survey to identify candidate\ngravitationally lensed quasar systems in a sample of WISE sources with W1 - W2\n> 0.7. Results from followup spectroscopy with the Baade 6.5 m telescope are\npresented for eight systems. One of these is a quadruply lensed quasar and two\nare doubly lensed systems. Two are projected superpositions of two quasars at\ndifferent redshifts. In one system two quasars, though at the same redshift,\nhave very different emission line profiles, and constitute a physical binary.\nIn two systems the component spectra are consistent with the lensing\nhypothesis, after allowing for micro-lensing. But as no lensing galaxy is\ndetected in these two, we classify them as lensless twins. More extensive\nobservations are needed to establish whether they are in fact lensed quasars or\nphysical binaries." }, { "anchor": "Local photoionization feedback effects on galaxies: We implement an optically thin approximation for the effects of the local\nradiation field from stars and hot gas on the gas heating and cooling in the\nN-body SPH code GASOLINE2. We resimulate three galaxies from the NIHAO project:\none dwarf, one Milky Way-like and one massive spiral, and study what are the\nlocal radiation field effects on various galaxy properties. We also study the\neffects of varying the Ultra Violet Background (UVB) model, by running the same\ngalaxies with two different UVBs. Galaxy properties at $z=0$ like stellar mass,\nstellar effective mass radius, HI mass, and radial extent of the HI disc, show\nsignificant changes between the models with and without the local radiation\nfield, and smaller differences between the two UVB models. The intrinsic effect\nof the local radiation field through cosmic time is to increase the equilibrium\ntemperature at the interface between the galaxies and their circumgalactic\nmedia (CGM), moving this boundary inwards, while leaving relatively unchanged\nthe gas inflow rate. Consequently, the temperature of the inflow increases when\nconsidering the local radiation sources. This temperature increase is a\nfunction of total galaxy mass, with a median CGM temperature difference of one\norder of magnitude for the massive spiral. The local radiation field suppresses\nthe stellar mass growth by $\\sim$20 per cent by $z=0$ for all three galaxies,\nwhile the HI mass is roughly halfed. The differences in the gas phase diagrams,\nsignificantly impact the HI column densities, shifting their peaks in the\ndistributions towards lower $N_{\\rm HI}$.", "positive": "On the effects of photoionization feedback on second-generation star\n formation in globular clusters of different masses: We simulate the formation of second-generation stars in young clusters with\nmasses of $10^{5}$ and $10^6\\ {\\rm M_\\odot}$ within $30-100\\ {\\rm Myr}$ after\nthe formation of clusters. We assume the clusters move through a uniform\ninterstellar medium with gas densities of $10^{-24}$ and $10^{-23}\\ {\\rm\ngcm}^{-3} $ and consider the stellar winds from asymptotic giant branch (AGB)\nstars, gas accretion onto the cluster, ram pressure, star formation, and\nphotoionization feedback of our stellar systems including binary stars. We find\nthat second-generation (SG) stars can be formed only within the $10^6\\ {\\rm\nM_\\odot}$ cluster in the high-density simulation, where the cluster can accrete\nsufficient pristine gas from their surrounding medium, leading to efficient\ncooling required for the ignition of SG formation and sufficient dilution of\nthe AGB ejecta. Hence, our results indicate that a denser environment is\nanother requirement for the AGB scenario to explain the presence of multiple\npopulations in globular clusters. On the other hand, the ionizing feedback\nbecomes effective in heating the gas in our low-density simulations. As a\nresult, the clusters cannot accumulate a considerable amount of pristine gas at\ntheir center. The gas mass within the clusters in these simulations is similar\nto that in young massive clusters (YMCs). Hence, our studies can provide a\npossible reason for the lack of gas, star formation, and SG stars in YMCs. Our\nresults indicate that the ionizing stellar feedback is not a severe problem for\nSG formation; rather, it can help the AGB scenario to account for some\nobservables." }, { "anchor": "A wide-field CO survey towards the California Molecular Filament: We present the survey of $^{12}$CO/$^{13}$CO/C$^{18}$O (J=1-0) toward the\nCalifornia Molecular Cloud (CMC) within the region of 161.75$^{\\circ} \\leqslant\nl \\leqslant$ 167.75$^{\\circ}$,-9.5$^{\\circ} \\leqslant b \\leqslant\n$-7.5$^{\\circ}$, using the Purple Mountain Observatory (PMO) 13.7 m millimeter\ntelescope. Adopting a distance of 470 pc, the mass of the observed molecular\ncloud estimated from $^{12}$CO, $^{13}$CO, and C$^{18}$O is about\n2.59$\\times$10$^{4}$ M$_\\odot$, 0.85$\\times$10$^{4}$ M$_\\odot$, and\n0.09$\\times$10$^{4}$ M$_\\odot$, respectively. A large-scale continuous filament\nextending about 72 pc is revealed from the $^{13}$CO images. A systematic\nvelocity gradient perpendicular to the major axis appears and is measured to be\n$\\sim$ 0.82 km s$^{-1}$ pc$^{-1}$. The kinematics along the filament shows an\noscillation pattern with a fragmentation wavelength of $\\sim$ 2.3 pc and\nvelocity amplitude of $\\sim$ 0.92 km s$^{-1}$, which may be related with\ncore-forming flows. Furthermore, assuming an inclination angle to the plane of\nthe sky of 45$^{\\circ}$, the estimated average accretion rate is $\\sim$ 101\nM$_\\odot$ Myr$^{-1}$ for the cluster LkH$\\alpha$ 101 and $\\sim$ 21 M$_\\odot$\nMyr$^{-1}$ for the other regions. In the C$^{18}$O observations, the\nlarge-scale filament could be resolved into multiple substructures and their\ndynamics are consistent with the scenario of filament formation from converging\nflows. Approximately 225 C$^{18}$O cores are extracted, of which 181 are\nstarless cores. Roughly 37$\\%$ (67/181) of the starless cores have\n$\\alpha_{\\text{vir}}$ less than 1. Twenty outflow candidates are identified\nalong the filament. Our results indicate active early-phase star formation\nalong the large-scale filament in the CMC region.", "positive": "Galactic bar resonances with diffusion: an analytic model with\n implications for bar-dark matter halo dynamical friction: The secular evolution of disk galaxies is largely driven by resonances\nbetween the orbits of 'particles' (stars or dark matter) and the rotation of\nnon-axisymmetric features (spiral arms or a bar). Such resonances may also\nexplain kinematic and photometric features observed in the Milky Way and\nexternal galaxies. In simplified cases, these resonant interactions are well\nunderstood: for instance, the dynamics of a test particle trapped near a\nresonance of a steadily rotating bar is easily analyzed using the angle-action\ntools pioneered by Binney, Monari and others. However, such treatments do not\naddress the stochasticity and messiness inherent to real galaxies - effects\nwhich have, with few exceptions, been previously explored only with complex\nN-body simulations. In this paper, we propose a simple kinetic equation\ndescribing the distribution function of particles near an orbital resonance\nwith a rigidly rotating bar, allowing for diffusion of the particles' slow\nactions. We solve this equation for various values of the dimensionless\ndiffusion strength $\\Delta$, and then apply our theory to the calculation of\nbar-halo dynamical friction. For $\\Delta = 0$ we recover the classic result of\nTremaine & Weinberg that friction ultimately vanishes, owing to the\nphase-mixing of resonant orbits. However, for $\\Delta > 0$ we find that\ndiffusion suppresses phase-mixing, leading to a finite torque. Our results\nsuggest that stochasticity - be it physical or numerical - tends to increase\nbar-halo friction, and that bars in cosmological simulations might experience\nsignificant artificial slowdown, even if the numerical two-body relaxation time\nis much longer than a Hubble time." }, { "anchor": "The Next Generation Virgo Cluster Survey (NGVS). XXIV. The Red Sequence\n to $\\sim$10$^6$ L$_{\\odot}$ and Comparisons with Galaxy Formation Models: We use deep optical photometry from the Next Generation Virgo Cluster Survey\n[NGVS] to investigate the color-magnitude diagram for the galaxies inhabiting\nthe core of this cluster. The sensitivity of the NGVS imaging allows us to\ncontinuously probe galaxy colors over a factor of $\\sim 2 \\times 10^5$ in\nluminosity, from brightest cluster galaxies to scales overlapping classical\nsatellites of the Milky Way [$M_{g^{\\prime}}$ $\\sim$ $-$9; $M_{*}$ $\\sim 10^6$\nM$_{\\odot}$], within a single environment. Remarkably, we find the first\nevidence that the RS flattens in all colors at the faint-magnitude end\n[starting between $-$14 $\\le$ $M_{g^{\\prime}}$ $\\le$ $-$13, around $M_{*}$\n$\\sim 4 \\times 10^7$ M$_{\\odot}$], with the slope decreasing to $\\sim$60% or\nless of its value at brighter magnitudes. This could indicate that the stellar\npopulations of faint dwarfs in Virgo's core share similar characteristics [e.g.\nconstant mean age] over $\\sim$3 mags in luminosity, suggesting that these\ngalaxies were quenched coevally, likely via pre-processing in smaller hosts. We\nalso compare our results to galaxy formation models, finding that the RS in\nmodel clusters have slopes at intermediate magnitudes that are too shallow, and\nin the case of semi-analytic models, do not reproduce the flattening seen at\nboth extremes [bright/faint] of the Virgo RS. Deficiencies in the chemical\nevolution of model galaxies likely contribute to the model-data discrepancies\nat all masses, while overly efficient quenching may also be a factor at dwarf\nscales. Deep UV and near-IR photometry are required to unambiguously diagnose\nthe cause of the faint-end flattening.", "positive": "Accuracy and precision of triaxial orbit models II: Viewing angles,\n shape and orbital structure: We explore the potential of our novel triaxial modeling machinery in\nrecovering the viewing angles, the shape and the orbit distribution of galaxies\nby using a high-resolution $N$-body merger simulation. Our modelling technique\nincludes several recent advancements. (i) Our new triaxial deprojection\nalgorithm SHAPE3D is able to significantly shrink the range of possible\norientations of a triaxial galaxy and therefore to constrain its shape relying\nonly on photometric information. It also allows to probe degeneracies, i.e. to\nrecover different deprojections at the same assumed orientation. With this\nmethod we can constrain the intrinsic shape of the $N$-body simulation, i.e.\nthe axis ratios $p=b/a$ and $q=c/a$, with $\\Delta p$ and $\\Delta q$ $\\lesssim$\n0.1 using only photometric information. The typical accuracy of the viewing\nangles reconstruction is 15-20$^\\circ$. (ii) Our new triaxial Schwarzschild\ncode SMART exploits the full kinematic information contained in the entire\nnon-parametric line-of-sight velocity distributions (LOSVDs) along with a 5D\norbital sampling in phase space. (iii) We use a new generalised information\ncriterion AIC$_p$ to optimise the smoothing and to select the best-fit model,\navoiding potential biases in purely $\\chi^2$-based approaches. With our\ndeprojected densities, we recover the correct orbital structure and anisotropy\nparameter $\\beta$ with $\\Delta \\beta$ $\\lesssim$ 0.1. These results are valid\nregardless of the tested orientation of the simulation and suggest that even\ndespite the known intrinsic photometric and kinematic degeneracies the above\ndescribed advanced methods make it possible to recover the shape and the\norbital structure of triaxial bodies with unprecedented accuracy." }, { "anchor": "Astrochemistry: the issue of molecular complexity in astrophysical\n environments: Astrochemistry aims at studying chemical processes in astronomical\nenvironments. This discipline -- located at the crossroad between astrophysics\nand chemistry -- is rapidly evolving and explores the issue of the formation of\nmolecules of increasing complexity in particular physical conditions that\ndeviate significantly from those frequently encountered in chemistry\nlaboratories. The main goal of this paper is to provide an overview of this\ndiscipline. So far, about 170 molecules have been identified in the\ninterstellar medium (ISM). The presence of this molecular diversity constitutes\na firm evidence that efficient formation processes are at work in the\ninterstellar medium. This paper aims at summarizing most of present ideas that\nare explored by astrochemists to investigate the chemistry taking place in\nvarious astronomical environments, with emphasis on the particular conditions\nwhich are met in space (including radiation fields, cosmic-rays, low\ndensities...). The more ambitious question of the molecular complexity is\naddressed following two approaches presented to be converging. The first\napproach considers the growing complexity starting from the most simple\nchemical species in interstellar environments, and the second approach\nenvisages successive precursors of the most complex species commonly found on\nEarth, and in particular in our biochemistry. The issue of molecular complexity\nconstitutes one of the main modern scientific questions addressed by\nastrochemistry, and it is used as a guideline across this paper.", "positive": "On the Formation of Elliptical Rings in Disk Galaxies: N-body simulations of galactic collisions are employed to investigate the\nformation of elliptical rings in disk galaxies. The relative inclination\nbetween disk and dwarf galaxies is studied with a fine step of five degrees. It\nis confirmed that the eccentricity of elliptical ring is linearly proportional\nto the inclination angle. Deriving from the simulational results, an analytic\nformula which expresses the eccentricity as a function of time and inclination\nangle is obtained. This formula shall be useful for the interpretations of the\nobservations of ring systems, and therefore reveals the merging histories of\ngalaxies." }, { "anchor": "Chemodynamics of the Milky Way and disc formation history: insight from\n the RAVE and Gaia-ESO surveys: Multi-object spectrographs have opened a new window on the analyses of the\nchemo-dynamical properties of old Milky Way stars. These analyses allow us to\ntrace back the internal mechanisms and the external factors that have\ninfluenced the evolution of our Galaxy, and therefore understand fundamental\naspects of galaxy evolution in general. Here, we present recent results from\nthe RAdial Velocity Experiment (RAVE) and the Gaia-ESO survey. These surveys\nexplore the Milky Way properties in different ways, in terms of sample size and\nselection, magnitude range, and spectral resolution. We focus here on (i) the\nfirst direct detection of evidence for radial migration within the thin disc,\nproviding insight into the history of spiral structure of the Milky Way, and\n(ii) the chemo-dynamical characterisation of the metal-weak thick and thin\ndiscs, for which chemo-dynamical models still have difficulties in reproducing.", "positive": "Stellar mass functions of galaxies at 411$) galaxies at $44$ galaxies with best fit masses $\\log(M_*/M_\\odot)>11$ by 83%, implying\na rapid growth of very massive galaxies in the first 1.5 Gyr of cosmic history.\nFrom the stellar-mass complete sample, we identify one candidate of a very\nmassive ($\\log(M_*/M_\\odot)\\sim11.5$), quiescent galaxy at $z\\sim5.4$, with\nMIPS $24\\mu$m detection suggesting the presence of a powerful obscured AGN." }, { "anchor": "Stars on the edge: Galactic tides and the outskirts of the Sculptor\n dwarf spheroidal: The formation of \"stellar halos\" in dwarf galaxies have been discussed in\nterms of early mergers or Galactic tides, although fluctuations in the\ngravitational potential due to stellar feedback is also a possible candidate\nmechanism. A Bayesian algorithm is used to find new candidate members in the\nextreme outskirts of the Sculptor dwarf galaxy. Precise metallicities and\nradial velocities for two distant stars are measured from their spectra taken\nwith the Gemini South GMOS spectrograph. The radial velocity, proper motion and\nmetallicity of these targets are consistent with Sculptor membership. As a\nresult, the known boundary of the Sculptor dwarf extends now out to an\nelliptical distance of $\\sim10$ half-light radii, which corresponds to a\nprojected physical distance of $\\sim3$ kpc. As reported in earlier work, the\noverall distribution of radial velocities and metallicities indicate the\npresence of a more spatially and kinematically dispersed metal-poor population\nthat surrounds the more concentrated and colder metal-rich stars. Sculptor's\ndensity profile shows a \"kink\" in its logarithmic slope at a projected distance\nof $\\sim25$ arcmin (620 pc), which we interpret as evidence that Galactic tides\nhave helped to populate the distant outskirts of the dwarf. We discuss further\nways to test and validate this tidal interpretation for the origin of these\ndistant stars.", "positive": "Young, blue, and isolated stellar systems in the Virgo Cluster. II. A\n new class of stellar system: We discuss five blue stellar systems in the direction of the Virgo cluster,\nanalogous to the enigmatic object SECCO 1 (AGC 226067). These objects were\nidentified based on their optical and UV morphology and followed up with HI\nobservations with the VLA (and GBT), MUSE/VLT optical spectroscopy, and HST\nimaging. These new data indicate that one system is a distant group of\ngalaxies. The remaining four are extremely low mass ($M_\\ast \\sim 10^5 \\;\n\\mathrm{M_\\odot}$), are dominated by young, blue stars, have highly irregular\nand clumpy morphologies, are only a few kpc across, yet host an abundance of\nmetal-rich, $12 + \\log (\\mathrm{O/H}) > 8.2$, HII regions. These high\nmetallicities indicate that these stellar systems formed from gas stripped from\nmuch more massive galaxies. Despite the young age of their stellar populations,\nonly one system is detected in HI, while the remaining three have minimal (if\nany) gas reservoirs. Furthermore, two systems are surprisingly isolated and\nhave no plausible parent galaxy within $\\sim$30' ($\\sim$140 kpc). Although\ntidal stripping cannot be conclusively excluded as the formation mechanism of\nthese objects, ram pressure stripping more naturally explains their properties,\nin particular their isolation, owing to the higher velocities, relative to the\nparent system, that can be achieved. Therefore, we posit that most of these\nsystems formed from ram pressure stripped gas removed from new infalling\ncluster members, and survived in the intracluster medium long enough to become\nseparated from their parent galaxies by hundreds of kiloparsecs, and that they\nthus represent a new type of stellar system." }, { "anchor": "Synthetic X-ray and radio maps for two different models of Stephan's\n Quintet: We present simulations of the compact galaxy group Stephan's Quintet (SQ)\nincluding magnetic fields, performed with the N-body/smoothed particle\nhydrodynamics (SPH) code \\textsc{Gadget}. The simulations include radiative\ncooling, star formation and supernova feedback. Magnetohydrodynamics (MHD) is\nimplemented using the standard smoothed particle magnetohydrodynamics (SPMHD)\nmethod. We adapt two different initial models for SQ based on Renaud et al. and\nHwang et al., both including four galaxies (NGC 7319, NGC 7320c, NGC 7318a and\nNGC 7318b). Additionally, the galaxies are embedded in a magnetized, low\ndensity intergalactic medium (IGM). The ambient IGM has an initial magnetic\nfield of $10^{-9}$ G and the four progenitor discs have initial magnetic fields\nof $10^{-9} - 10^{-7}$ G. We investigate the morphology, regions of star\nformation, temperature, X-ray emission, magnetic field structure and radio\nemission within the two different SQ models. In general, the enhancement and\npropagation of the studied gaseous properties (temperature, X-ray emission,\nmagnetic field strength and synchrotron intensity) is more efficient for the SQ\nmodel based on Renaud et al., whose galaxies are more massive, whereas the less\nmassive SQ model based on Hwang et al. shows generally similar effects but with\nsmaller efficiency. We show that the large shock found in observations of SQ is\nmost likely the result of a collision of the galaxy NGC 7318b with the IGM.\nThis large group-wide shock is clearly visible in the X-ray emission and\nsynchrotron intensity within the simulations of both SQ models. The order of\nmagnitude of the observed synchrotron emission within the shock front is\nslightly better reproduced by the SQ model based on Renaud et al., whereas the\ndistribution and structure of the synchrotron emission is better reproduced by\nthe SQ model based on Hwang et al..", "positive": "Neutral-Gas-Phase Metal Abundances in ZnII-Selected Quasar Absorption\n Line Systems near Redshift $z=1.2$: We present ten metallicity measurements for quasar absorbers near $z=1.2$\nthat were selected for having unusually significant ZnII absorption in their\nSDSS spectra. Follow-up UV space spectroscopy of the Ly$\\alpha$ region shows\nthat all ten have damped Ly$\\alpha$ (DLA) absorption, corresponding to neutral\nhydrogen column densities in the range $2.4\\times 10^{20}$ $\\le$ N(HI) $\\le$\n$2.5\\times 10^{21}$ atoms cm$^{-2}$, and indicating that the gas is very\noptically thick and essentially neutral. The sample is a very small subset of\nsystems compiled by searching the University of Pittsburgh catalog of $\\approx\n30,000$ intervening MgII absorption line systems in SDSS quasar spectra up to\nDR7. We started by isolating $\\approx 3,000$ that had strong MgII absorption in\nthe redshift interval $1.0 < z < 1.5$ in brighter background quasars. Of these,\n36 exhibited significant absorption near ZnII. Space UV spectroscopy was then\nobtained for nine of these (25% of the total), and a tenth system in a fainter\nquasar was found in the HST archives. The result is a representative sample of\nthe highest Zn$^+$ columns of gas within the DLA population. These\nZnII-selected systems define the upper envelope of DLA metallicities near\n$z=1.2$. They show a tight anti-correlation between N(HI) and [Zn/H], with the\nhigher metallicity systems clearly exhibiting more depletion based on [Cr/Zn]\nvalues. The various metal-line measurements (Zn, Cr, Si, Fe, Mn) indicate\nevolved neutral gas with $-0.9 \\le$ [Zn/H] $\\le +0.4$." }, { "anchor": "Ultra fast outflows, and their connection to accretion and ejection\n processes in AGNs: The growing evidence for energy-conserving outflows in powerful and luminous\nAGN supports the idea that high-velocity winds launched from the accretion disc\nevolve systematically after undergoing a shock with the ambient medium and that\nthey are capable to expel enough mass and energy so as to produce feedback.\nThis talk will give an overview of recent results on AGN ultra fast outflows,\nwith focus on grating X-ray spectra of bright sources. I will review how UFO\nwork, their observational properties and their relation with AGN outflows in\nother bands, what is their impact on the host galaxies and their role in\nfeedback processes.", "positive": "Galaxy Formation with Self-consistently Modeled Stars and Massive Black\n Holes. I: Feedback-regulated Star Formation and Black Hole Growth: There is mounting evidence for the coevolution of galaxies and their embedded\nmassive black holes (MBHs) in a hierarchical structure formation paradigm. To\ntackle the nonlinear processes of galaxy-MBH interaction, we describe a\nself-consistent numerical framework which incorporates both galaxies and MBHs.\nThe high-resolution adaptive mesh refinement (AMR) code Enzo is modified to\nmodel the formation and feedback of molecular clouds at their characteristic\nscale of 15.2 pc and the accretion of gas onto a MBH. Two major channels of MBH\nfeedback, radiative feedback (X-ray photons followed through full 3D adaptive\nray tracing) and mechanical feedback (bipolar jets resolved in high-resolution\nAMR), are employed. We investigate the coevolution of a 9.2e11 Msun galactic\nhalo and its 1e5 Msun embedded MBH at redshift 3 in a cosmological LCDM\nsimulation. The MBH feedback heats the surrounding ISM up to 1e6 K through\nphotoionization and Compton heating and locally suppresses star formation in\nthe galactic inner core. The feedback considerably changes the stellar\ndistribution there. This new channel of feedback from a slowly growing MBH is\nparticularly interesting because it is only locally dominant, and does not\nrequire the heating of gas globally on the disk. The MBH also self-regulates\nits growth by keeping the surrounding ISM hot for an extended period of time." }, { "anchor": "The origin of the relation between metallicity and size in star-forming\n galaxies: For the same stellar mass, physically smaller star-forming galaxies are also\nmetal richer (Ellison et al. 2008). What causes the relation remains unclear.\nThe central star-forming galaxies in the EAGLE cosmological numerical\nsimulation reproduce the observed trend. We use them to explore the origin of\nthe relation assuming that the physical mechanism responsible for the\nanti-correlation between size and gas-phase metallicity is the same in the\nsimulated and the observed galaxies. We consider the three most likely causes:\n(1) metal-poor gas inflows feeding the star-formation process, (2) metal-rich\ngas outflows particularly efficient in shallow gravitational potentials, and\n(3) enhanced efficiency of the star-formation process in compact galaxies.\nOutflows (2) and enhanced star-formation efficiency (3) can be discarded.\nMetal-poor gas inflows (1) cause the correlation in the simulated galaxies.\nGalaxies grow in size with time, so those that receive gas later are both metal\npoorer and larger, giving rise to the observed anti-correlation. As expected\nwithin this explanation, larger galaxies have younger stellar populations. We\nexplore the variation with redshift of the relation, which is maintained up to,\nat least, redshift 8.", "positive": "CIV Emission Line Properties and Systematic Trends in Quasar Black Hole\n Mass Estimates: Black-hole masses are crucial to understanding the physics of the connection\nbetween quasars and their host galaxies and measuring cosmic black hole-growth.\nAt high redshift, z > 2.1, black hole masses are normally derived using the\nvelocity-width of the CIV broad emission line, based on the assumption that the\nobserved velocity-widths arise from virial-induced motions. In many quasars,\nthe CIV-emission line exhibits significant blue asymmetries (`blueshifts') with\nthe line centroid displaced by up to thousands of km/s to the blue. These\nblueshifts almost certainly signal the presence of strong outflows, most likely\noriginating in a disc wind. We have obtained near-infrared spectra, including\nthe H$\\alpha$ emission line, for 19 luminous ($L_{Bol}$ = 46.5-47.5 erg/s)\nSloan Digital Sky Survey quasars, at redshifts 2 < z < 2.7, with CIV emission\nlines spanning the full-range of blueshifts present in the population. A strong\ncorrelation between CIV-velocity width and blueshift is found and, at large\nblueshifts, > 2000 km/s, the velocity-widths appear to be dominated by\nnon-virial motions. Black-hole masses, based on the full width at half maximum\nof the CIV-emission line, can be overestimated by a factor of five at large\nblueshifts. A larger sample of quasar spectra with both CIV and H$\\beta$, or\nH$\\alpha$, emission lines will allow quantitative corrections to CIV-based\nblack-hole masses as a function of blueshift to be derived. We find that\nquasars with large CIV blueshifts possess high Eddington luminosity ratios and\nthat the fraction of high-blueshift quasars in a flux-limited sample is\nenhanced by a factor of approximately four relative to a sample limited by\nblack hole mass." }, { "anchor": "The Origin and Shaping of Planetary Nebulae: Putting the Binary\n Hypothesis to the Test: Planetary nebulae (PNe) are circumstellar gas ejected during an intense\nmass-losing phase in the the lives of asymptotic giant branch stars. PNe have a\nstunning variety of shapes, most of which are not spherically symmetric. The\ndebate over what makes and shapes the circumstellar gas of these evolved,\nintermediate mass stars has raged for two decades. Today the community is\nreaching a consensus that single stars cannot trivially manufacture PNe and\nimpart to them non spherical shapes and that a binary companion, possibly even\na sub-stellar one, might be needed in a majority of cases. This theoretical\nconjecture has however not been tested observationally. In this review we\ndiscuss the problem both from the theoretical and observational standpoints,\nexplaining the obstacles that stand in the way of a clean observational test\nand ways to ameliorate the situation. We also discuss indirect tests of this\nhypothesis and its implications for stellar and galactic astrophysics.", "positive": "IGRINS spectroscopy of Class I sources: IRAS 03445+3242 and IRAS\n 04239+2436: We have detected molecular and atomic line emission from the hot and warm\ndisks of two Class I sources, IRAS 03445+3242 and IRAS 04239+2436 using the\nhigh resolution Immersion GRating INfrared Spectrograph (IGRINS). CO overtone\nband transitions and near-IR lines of Na I and Ca I, all in emission, trace the\nhot inner disk while CO rovibrational absorption spectra of the first overtone\ntransition trace the warm gas within the inner few AU of the disk. The\nemission-line profiles for both sources show evidence for Keplerian disks. A\nthin Keplerian disk with power-law temperature and column density profiles with\na projected rotational velocity of $\\sim$60--75 km s$^{-1}$ and a gas\ntemperature of $\\sim$3500 K at the innermost annulus can reproduce the CO\novertone band emission. Na I and Ca I emission lines also arise from this disk,\nbut they show complicated line features possibly affected by photospheric\nabsorption lines. Multi-epoch observations show asymmetric variations of the\nline profiles on one-year (CO overtone bandhead and atomic lines for IRAS\n03445+3242) or on one-day (atomic lines for IRAS 04239+2436) time scales,\nimplying non-axisymmetric features in disks. The narrow CO rovibrational\nabsorption spectra ($v$=0$\\rightarrow$2) indicate that both warm ($>$ 150 K)\nand cold ($\\sim$20--30 K) CO gas are present along the line of sight to the\ninner disk. This study demonstrates the power of IGRINS as a tool for studies\nof the sub-AU scale hot and AU-scale warm protoplanetary disks with its\nsimultaneous coverage of the full H and K bands with high spectral resolution\n($R$= 45,000) allowing many aspects of the sources to be investigated at once." }, { "anchor": "A third red supergiant rich cluster in the Scutum-Crux Arm: We aim to characterise the properties of a third massive, red supergiant\ndominated galactic cluster. To accomplish this we utilised a combination of\nnear/mid-IR photometry and spectroscopy to identify and classify the properties\nof cluster members, and statistical arguments to determine the mass of the\ncluster. We found a total of 16 strong candidates for cluster membership, for\nwhich formal classification of a subset yields spectral types from K3-M4 Ia and\nluminosities between log(L/L_sun)~4.5-4.8 for an adopted distance of 6+/-1 kpc.\nFor an age in the range of 16-20 Myr, the implied mass is 2-4x10^4 M_sun,\nmaking it one of the most massive young clusters in the Galaxy. This discovery\nsupports the hypothesis that a significant burst of star formation occurred at\nthe base of Scutum-Crux arm between 10-20 Myr ago, yielding a stellar complex\ncomprising at least ~10^5M_sun of stars (noting that since the cluster\nidentification criteria rely on the presence of RSGs, we suspect that the true\nstellar yield will be significantly higher). We highlight the apparent absence\nof X-ray binaries within the star formation complex and finally, given the\nphysical association of at least two pulsars with this region, discuss the\nimplications of this finding for stellar evolution and the production and\nproperties of neutron stars.", "positive": "On the origin of the helium-rich population in Omega Centauri: To study the possible origin of the huge helium enrichment attributed to the\nstars on the blue main sequence of Omega Centauri, we make use of a chemical\nevolution model that has proven able to reproduce other major observed\nproperties of the cluster, namely, its stellar metallicity distribution\nfunction, age-metallicity relation and trends of several abundance ratios with\nmetallicity. In this framework, the key condition to satisfy all the available\nobservational constraints is that a galactic-scale outflow develops in a much\nmore massive parent system, as a consequence of multiple supernova explosions\nin a shallow potential well. This galactic wind must carry out preferentially\nthe metals produced by explosive nucleosynthesis in supernovae, whereas\nelements restored to the interstellar medium through low-energy stellar winds\nby both asymptotic giant branch (AGB) stars and massive stars must be mostly\nretained. Assuming that helium is ejected through slow winds by both AGB stars\nand fast rotating massive stars (FRMSs), the interstellar medium of Omega\nCentauri's parent galaxy gets naturally enriched in helium in the course of its\nevolution." }, { "anchor": "A Tale of 3 Dwarfs: No Extreme Cluster Formation in Extreme Star-Forming\n Galaxies: Nearly all current simulations predict that outcomes of the star formation\nprocess, such as the fraction of stars that form in bound clusters (Gamma),\ndepend on the intensity of star formation activity (SigmaSFR) in the host\ngalaxy. The exact shape and strength of the predicted correlations, however,\nvary from simulation to simulation. Observational results also remain unclear\nat this time, because most works have mixed estimates made from very young\nclusters for galaxies with higher SigmaSFR with those from older clusters for\ngalaxies with lower SigmaSFR. The three blue compact dwarf (BCD) galaxies\nESO185-IG13, ESO338-IG04, and Haro11 have played a central role on the\nobservational side because they have some of the highest known SigmaSFR and\npublished values of Gamma. We present new estimates of Gamma for these BCDs in\nthree age intervals (1-10 Myr, 10-100 Myr, 100-400 Myr), based on age-dating\nwhich includes Halpha photometry to better discriminate between clusters\nyounger and older than ~10 Myr. We find significantly lower values for Gamma\n(1-10 Myr) than published previously. The likely reason for the discrepancy is\nthat previous estimates appear to be based on age-reddening results that\nunderestimated ages and overestimated reddening for many clusters, artificially\nboosting Gamma (1-10 Myr). We also find that fewer stars remain in clusters\nover time, with ~15-39% in 1-10 Myr, ~5-7% in 10-100 Myr, and ~1-2% in 100-400\nMyr clusters. We find no evidence that Gamma increases with SigmaSFR. These\nresults imply that cluster formation efficiency does not vary with star\nformation intensity in the host galaxy. If confirmed, our results will help\nguide future assumptions in galaxy-scale simulations of cluster formation and\nevolution.", "positive": "Far-infrared/sub-millimetre properties of pre-stellar cores L1521E,\n L1521F and L1689B as revealed by the Herschel SPIRE instrument -- I. Central\n positions: Dust grains play a key role in the physics of star-forming regions, even\nthough they constitute only $\\sim$1 % of the mass of the interstellar medium.\nThe derivation of accurate dust parameters such as temperature ($T_{dust}$),\nemissivity spectral index ($\\beta$) and column density requires broadband\ncontinuum observations at far-infrared wavelengths. We present Herschel-SPIRE\nFourier Transform Spectrometer (FTS) measurements of three starless cores:\nL1521E, L1521F and L1689B, covering wavelengths between 194 and 671 $\\mu$m.\nThis paper is the first to use our recently updated SPIRE-FTS intensity\ncalibration, yielding a direct match with SPIRE photometer measurements of\nextended sources. In addition, we carefully assess the validity of calibration\nschemes depending on source extent and on the strength of background emission.\nThe broadband far-infrared spectra for all three sources peak near 250 $\\mu$m.\nOur observations therefore provide much tighter constraints on the spectral\nenergy distribution (SED) shape than measurements that do not probe the SED\npeak. The spectra are fitted using modified blackbody functions, allowing both\n$T_{dust}$ and $\\beta$ to vary as free parameters. This yields $T_{dust}$ of\n9.8$\\pm$0.2 K, 15.6$\\pm$0.5 K and 10.9$\\pm$0.2 K and corresponding $\\beta$ of\n2.6$\\mp$0.9, 0.8$\\mp$0.1 and 2.4$\\mp$0.8 for L1521E, L1521F and L1689B\nrespectively. The derived core masses are 1.0$\\pm$0.1, 0.10$\\pm$0.01 and\n0.49$\\pm$0.05 $M_{\\odot}$, respectively. The core mass/Jeans mass ratios for\nL1521E and L1689B exceed unity indicating that they are unstable to\ngravitational collapse, and thus pre-stellar cores. By comparison, the elevated\ntemperature and gravitational stability of L1521F support previous arguments\nthat this source is more evolved and likely a protostar." }, { "anchor": "Evolution of CIV Absorbers I. The Cosmic Incidence: We present a large high-resolution study of the distribution and evolution of\nCIV absorbers, including the weakest population with equivalent widths\n$W_r<0.3$~{\\AA}. By searching 369 high-resolution, high signal-to-noise spectra\nof quasars at $1.1\\leq z_{em} \\leq5.3$ from Keck/HIRES and VLT/UVES, we find\n$1268$ CIV absorbers with $W_r \\geq 0.05$~{\\AA} (our $\\sim50\\%$ completeness\nlimit) at redshifts $1\\leq z \\leq4.75$. A Schechter function describes the\nobserved equivalent width distribution with a transition from power-law to\nexponential decline at $W_r \\gtrsim 0.5$~{\\AA}. The power-law slope $\\alpha$\nrises by $\\sim7\\%$ and transition equivalent width $W_{\\star}$ falls by\n$\\sim\\!20\\%$ from $\\langle z \\rangle=1.7$ to $\\langle z \\rangle=3.6$. We find\nthat the co-moving redshift path density, $dN/dX$, of $W_r \\geq 0.05$~{\\AA}\nabsorbers rises by $\\sim1.8$ times from $z\\simeq 4.0$ to $z\\simeq 1.3$, while\nthe $W_r \\geq 0.6$~{\\AA} $dN/dX$ rises by a factor of $\\sim8.5$. We quantify\nthe observed evolution by a model in which $dN/dX$ decreases linearly with\nredshift. The model suggests that populations with larger $W_r$ thresholds\nevolve faster with redshift and appear later in the universe. The cosmological\nTechnicolor Dawn simulations at $z=3-5$ over-produce the observed abundance of\nabsorbers with $W_r<0.3$~{\\AA}, while yielding better agreement at higher\n$W_r$. Our empirical linear model successfully describes {CIV evolution in the\nsimulations and the observed evolution of $W_r \\geq 0.6$~{\\AA} CIV for the past\n$\\sim12$ Gyr. Combining our measurements with the literature gives us a picture\nof CIV-absorbing structures becoming more numerous and/or larger in physical\nsize over the last $\\approx13$ Gyr of cosmic time ($z\\sim6$ to $z\\sim0$).", "positive": "The GALFA-HI Survey: Data Release 1: We present the Galactic Arecibo L-Band Feed Array HI (GALFA-HI) survey, and\nits first full data release (DR1). GALFA-HI is a high resolution (~ 4'), large\narea (13000 deg^2), high spectral resolution (0.18 km/s), wide band (-700 <\nv_LSR < +700 km/s) survey of the Galactic interstellar medium in the 21-cm line\nhyperfine transition of neutral hydrogen conducted at Arecibo Observatory.\nTypical noise levels are 80 mK RMS in an integrated 1 km/s channel. GALFA-HI is\na dramatic step forward in high-resolution, large-area Galactic HI surveys, and\nwe compare GALFA-HI to past, present, and future Galactic HI surveys. We\ndescribe in detail new techniques we have developed to reduce these data in the\npresence of fixed pattern noise, gain variation, and inconsistent beam shapes,\nand we show how we have largely mitigated these effects. We present our first\nfull data release, covering 7520 square degrees of sky and representing 3046\nhours of integration time, and discuss the details of these data." }, { "anchor": "Formation of H2-He substellar bodies in cold conditions: Gravitational\n stability of binary mixtures in a phase transition: Molecular clouds typically consist of 3/4 H2, 1/4 He and traces of heavier\nelements. In an earlier work we showed that at very low temperatures and high\ndensities, H2 can be in a phase transition leading to the formation of ice\nclumps as large as comets or even planets. However, He has very different\nchemical properties and no phase transition is expected before H2 in dense\ninterstellar medium (ISM) conditions. The gravitational stability of fluid\nmixtures has been studied before, but these studies did not include a phase\ntransition.\n First, we study the gravitational stability of van der Waals fluid mixtures\nusing linearized analysis and examine virial equilibrium conditions using the\nLennard-Jones intermolecular potential. Then, combining the Lennard-Jones and\ngravitational potentials, the non-linear dynamics of fluid mixtures are studied\nvia computer simulations using the molecular dynamics code LAMMPS.\n Along with the classical, ideal-gas Jeans instability criterion, a fluid\nmixture is always gravitationally unstable if it is in a phase transition\nbecause compression does not increase pressure. However, the condensed phase\nfraction increases. In unstable situations the species can separate: in some\nconditions He precipitates faster than H2, while in other conditions the\nconverse occurs. Also, for an initial gas phase collapse the geometry is\nessential. Contrary to spherical or filamentary collapses, sheet-like collapses\nstarting below 15K easily reach H2 condensation conditions because then they\nare fastest and both the increase of heating and opacity are limited.\n Depending on density, temperature and mass, either rocky H2 planetoids, or\ngaseous He planetoids form. H2 planetoids are favoured by high density, low\ntemperature and low mass, while He planetoids need more mass and can form at\ntemperature well above the critical value.", "positive": "A Molecular Line Investigation of the Interaction between Mid-infrared\n Bubbles and the Interstellar Medium: We used the Green Bank Telescope to detect molecular lines observed toward\nMid-Infrared (MIR) bubbles N62, N65, N90, and N117. The bubbles were selected\nfrom Watson et al. (2016) who detected non-Gaussian CS (1-0) emission lines\ntoward the bubbles. Two of the bubbles are adjacent to infrared dark clouds\n(IRDCs); we examined these sources for evidence of interaction between the\nbubble rim and IRDC. The other two bubbles contain YSOs interior to the bubble\nrim; in these sources we observed the gas near the YSOs. We detect CS (1-0)\nemission toward all of the sources, and in several pointings the CS emission\nshows non-Gaussian line shapes. HC$_3$N (5-4), C$^{34}$S (1-0), CH$_3$OH (1-0),\nand SiO (v=0) (1-0) were also detected in some pointings. We calculate column\ndensities and abundances for the detected molecules. We compare the velocity of\noptically-thick CS emission with the velocity of the other, optically thin\nlines to look for evidence of infall. We find that even in pointings with\nnon-Gaussian CS emission, our detections do not support an infall model. We\ninterpret the kinematics of the gas in N62, N65, and N117 as likely evidence of\nmultiple clouds along the line of sight moving at slightly offset velocities.\nWe do not detect evidence of bubble rims interacting with IRDCs in N62 or N90.\nThe gas interior to bubbles appears more disrupted than the gas in the IRDCs.\nN65 shows significantly stronger emission lines than the other sources, as well\nas the most complicated non-Gaussian line shapes." }, { "anchor": "Formation of Warped Disks by Galactic Fly-by Encounters. I. Stellar\n Disks: Warped disks are almost ubiquitous among spiral galaxies. Here we revisit and\ntest the `fly-by scenario' of warp formation, in which impulsive encounters\nbetween galaxies are responsible for warped disks. Based on N-body simulations,\nwe investigate the morphological and kinematical evolution of the stellar\ncomponent of disks when galaxies undergo fly-by interactions with adjacent dark\nmatter halos. We find that the so-called `S'-shaped warps can be excited by\nfly-bys and sustained for even up to a few billion years, and that this\nscenario provides a cohesive explanation for several key observations. We show\nthat disk warp properties are governed primarily by the following three\nparameters; (1) the impact parameter, i.e., the minimum distance between two\nhalos, (2) the mass ratio between two halos, and (3) the incident angle of the\nfly-by perturber. The warp angle is tied up with all three parameters, yet the\nwarp lifetime is particularly sensitive to the incident angle of the perturber.\nInterestingly, the modeled S-shaped warps are often non-symmetric depending on\nthe incident angle. We speculate that the puzzling U- and L-shaped warps are\ngeometrically superimposed S-types produced by successive fly-bys with\ndifferent incident angles, including multiple interactions with a satellite on\na highly elongated orbit.", "positive": "Search for Interstellar LiH in the Milky Way: We report the results of a sensitive search for the 443.952902 GHz $J=1-0$\ntransition of the LiH molecule toward two interstellar clouds in the Milky Way,\nW49N and Sgr B2 (Main), that has been carried out using the Atacama Pathfinder\nExperiment (APEX) telescope. The results obtained toward W49N place an upper\nlimit of $1.9 \\times 10^{-11}\\, (3\\sigma)$ on the LiH abundance, $N({\\rm\nLiH})/N({\\rm H}_2)$, in a foreground, diffuse molecular cloud along the\nsight-line to W49N, corresponding to 0.5% of the solar system lithium\nabundance. Those obtained toward Sgr B2 (Main) place an abundance limit $N({\\rm\nLiH})/N({\\rm H}_2) < 3.6 \\times 10^{-13} \\,(3\\sigma)$ in the dense gas within\nthe Sgr B2 cloud itself. These limits are considerably smaller that those\nimplied by the tentative detection of LiH reported previously for the $z=0.685$\nabsorber toward B0218+357." }, { "anchor": "Discovery of a Stellar Overdensity in Eridanus-Phoenix in the Dark\n Energy Survey: We report the discovery of an excess of main sequence turn-off stars in the\ndirection of the constellations of Eridanus and Phoenix from the first year\ndata of the Dark Energy Survey (DES). The Eridanus-Phoenix (EriPhe) overdensity\nis centered around l~285 deg and b~-60 deg and spans at least 30 deg in\nlongitude and 10 deg in latitude. The Poisson significance of the detection is\nat least 9 sigma. The stellar population in the overdense region is similar in\nbrightness and color to that of the nearby globular cluster NGC 1261,\nindicating that the heliocentric distance of EriPhe is about d~16 kpc. The\nextent of EriPhe in projection is therefore at least ~4 kpc by ~3 kpc. On the\nsky, this overdensity is located between NGC 1261 and a new stellar stream\ndiscovered by DES at a similar heliocentric distance, the so-called Phoenix\nStream. Given their similar distance and proximity to each other, it is\npossible that these three structures may be kinematically associated.\nAlternatively, the EriPhe overdensity is morphologically similar to the Virgo\noverdensity and the Hercules-Aquila cloud, which also lie at a similar\nGalactocentric distance. These three overdensities lie along a polar plane\nseparated by ~120 deg and may share a common origin. Spectroscopic follow-up\nobservations of the stars in EriPhe are required to fully understand the nature\nof this overdensity.", "positive": "On the Formation of Molecular Clumps in QSO Outflows: We study the origin of the cold molecular clumps in quasar outflows, recently\ndetected in CO and HCN emission. We first describe the physical properties of\nsuch radiation-driven outflows and show that a transition from a momentum- to\nan energy-driven flow must occur at a radial distance of R ~ 0.25 kpc. During\nthis transition, the shell of swept up material fragments due to\nRayleigh-Taylor instabilities, but these clumps contain little mass and are\nlikely to be rapidly ablated by the hot gas in which they are immersed. We then\nexplore an alternative scenario in which clumps form from thermal instabilities\nat R >~ 1 kpc, possibly containing enough dust to catalyze molecule formation.\nWe investigate this processes with 3D two-fluid (gas+dust) numerical\nsimulations of a kpc^3 patch of the outflow, including atomic and dust cooling,\nthermal conduction, dust sputtering, and photoionization from the QSO radiation\nfield. In all cases, dust grains are rapidly destroyed in ~10,000 years; and\nwhile some cold clumps form at later times, they are present only as transient\nfeatures, which disappear as cooling becomes more widespread. In fact, we only\nfind a stable two-phase medium with dense clumps if we artificially enhance the\nQSO radiation field by a factor 100. This result, together with the complete\ndestruction of dust grains, renders the interpretation of molecular outflows a\nvery challenging problem." }, { "anchor": "ALMA [N \u0131\u0131] 205 \u03bcm Imaging Spectroscopy of the Lensed\n Submillimeter galaxy ID 141 at redshift 4.24: We present the Atacama Large Millimeter/submillimeter Array (ALMA)\nobservation of the Sub-millimeter galaxy (SMG) ID 141 at z=4.24 in the [N II]\n205 $\\mu$m line (hereafter [N II]) and the underlying continuum at (rest-frame)\n197.6 $\\mu$m. Benefiting from lensing magnification by a galaxy pair at\nz=0.595, ID 141 is one of the brightest z$>4$ SMGs. At the angular resolutions\nof $\\sim1.2\"$ to $1.5\"$ ($1\" \\sim6.9$ kpc), our observation clearly separates,\nand moderately resolves the two lensed images in both continuum and line\nemission at $\\rm S/N>5$ . Our continuum-based lensing model implies an averaged\namplification factor of $\\sim5.8$ and reveals that the de-lensed continuum\nimage has the S\\'ersic index $\\simeq 0.95$ and the S\\'ersic radius of\n$\\sim0.18\" (\\sim 1.24$ kpc). Furthermore, the reconstructed [N II] velocity\nfield in the source plane is dominated by a rotation component with a maximum\nvelocity of $\\sim 300$ km/s at large radii, indicating a dark matter halo mass\nof $\\sim 10^{12}M_{\\odot}$. This, together with the reconstructed velocity\ndispersion field being smooth and modest in value ($<100$ km/s) over much of\nthe outer parts of the galaxy, favours the interpretation of ID 141 being a\ndisk galaxy dynamically supported by rotation. The observed [N II]/CO (7-6) and\n[N II]/[C II] 158 $\\mu$m line luminosity ratios, which are consistent with the\ncorresponding line ratio vs. far-infrared color correlation from local luminous\ninfrared galaxies, imply a de-lensed star formation rate of ($1.8\\pm\n0.6)\\times10^3M_\\odot$/yr and provide an independent estimate on the size of\nthe star-forming region $0.7^{+0.3}_{-0.3}$ kpc in radius.", "positive": "Spatially resolved XMM-Newton analysis and a model of the nonthermal\n emission of MSH 15-52: We present an X-ray analysis and a model of the nonthermal emission of the\npulsar wind nebula (PWN) MSH15-52. We analyzed XMM-Newton data to obtain the\nspatially resolved spectral parameters around the pulsar PSRB1509-58. A\nsteepening of the fitted power-law spectra and decrease in the surface\nbrightness is observed with increasing distance from the pulsar. In the second\npart of this paper, we introduce a model for the nonthermal emission, based on\nassuming the ideal magnetohydrodynamic limit. This model is used to constrain\nthe parameters of the termination shock and the bulk velocity of the leptons in\nthe PWN. Our model is able to reproduce the spatial variation of the X-ray\nspectra. The parameter ranges that we found agree well with the parameter\nestimates found by other authors with different approaches. In the last part of\nthis paper, we calculate the inverse Compton emission from our model and\ncompare it to the emission detected with the H.E.S.S. telescope system. Our\nmodel is able to reproduce the flux level observed with H.E.S.S., but not the\nspectral shape of the observed TeV {\\gamma}-ray emission." }, { "anchor": "Star formation rates and the kinematics of gas in the spiral arms of NGC\n 628: Relations between star formation rates along the spiral arms and the\nvelocities of gas inflow into the arms in grand-design galaxy NGC 628 were\nstudied. We found that the radial distribution of average star formation rate\nin individual star formation regions in regular spiral arms correlates with the\nvelocity of gas inflow into the spiral arms. Both distributions have maxima at\na galactocentric distance of 4.5-5 kpc. There are no correlations between the\nradial distributions of average star formation rate in star formation regions\nin spiral arms and outside spiral arms in the main disc. We also did not find a\ncorrelation between the radial distribution of average star formation rate in\nstar formation regions in spiral arms and HI column density.", "positive": "No sign of strong molecular gas outflow in an infrared-bright\n dust-obscured galaxy with strong ionized-gas outflow: We report the discovery of an infrared (IR)-bright dust-obscured galaxy (DOG)\nthat shows a strong ionized-gas outflow but no significant molecular gas\noutflow. Based on detail analysis of their optical spectra, we found some\npeculiar IR-bright DOGs that show strong ionized-gas outflow\n([OIII]$\\lambda$5007) from the central active galactic nucleus (AGN). For one\nof these DOGs (WISE J102905.90+050132.4) at $z_{\\rm spec} = 0.493$, we\nperformed follow-up observations using ALMA to investigate their CO molecular\ngas properties. As a result, we successfully detected $^{12}$CO($J$=2-1) and\n$^{12}$CO($J$=4-3) lines, and the continuum of this DOG. The intensity-weighted\nvelocity map of both lines shows a gradient, and the line profile of those CO\nlines is well-fitted by a single narrow Gaussian, meaning that this DOG has no\nsign of strong molecular gas outflow. The IR luminosity of this object is\n$\\log\\,(L_{\\rm IR}/L_{\\odot})$ = 12.40 that is classified as ultraluminous IR\ngalaxy (ULIRG). We found that (i) the stellar mass and star-formation rate\nrelation and (ii) the CO luminosity and far-IR luminosity relation are\nconsistent with those of typical ULIRGs at similar redshifts. These results\nindicate that the molecular gas properties of this DOG are normal despite that\nits optical spectrum showing a powerful AGN outflow. We conclude that a\npowerful ionized-gas outflow caused by the AGN does not necessarily affect the\ncold interstellar medium in the host galaxy at least for this DOG." }, { "anchor": "Comparing PyMorph and SDSS photometry. I. Background sky and model\n fitting effects: A number of recent estimates of the total luminosities of galaxies in the\nSDSS are significantly larger than those reported by the SDSS pipeline. This is\nbecause of a combination of three effects: one is simply a matter of defining\nthe scale out to which one integrates the fit when defining the total\nluminosity, and amounts on average to < 0.1 mags even for the most luminous\ngalaxies. The other two are less trivial and tend to be larger; they are due to\ndifferences in how the background sky is estimated and what model is fit to the\nsurface brightness profile. We show that PyMorph sky estimates are fainter than\nthose of the SDSS DR7 or DR9 pipelines, but are in excellent agreement with the\nestimates of Blanton et al. (2011). Using the SDSS sky biases luminosities by\nmore than a few tenths of a magnitude for objects with half-light radii > 7\narcseconds. In the SDSS main galaxy sample these are typically luminous\ngalaxies, so they are not necessarily nearby. This bias becomes worse when\nallowing the model more freedom to fit the surface brightness profile. When\nPyMorph sky values are used, then two component Sersic-Exponential fits to\nE+S0s return more light than single component deVaucouleurs fits (up to ~0.2\nmag), but less light than single Sersic fits (0.1 mag). Finally, we show that\nPyMorph fits of Meert et al. (2015) to DR7 data remain valid for DR9 images.\nOur findings show that, especially at large luminosities, these PyMorph\nestimates should be preferred to the SDSS pipeline values.", "positive": "Predicting star formation properties of galaxies using deep learning: Understanding the star-formation properties of galaxies as a function of\ncosmic epoch is a critical exercise in studies of galaxy evolution.\nTraditionally, stellar population synthesis models have been used to obtain\nbest fit parameters that characterise star formation in galaxies. As multiband\nflux measurements become available for thousands of galaxies, an alternative\napproach to characterising star formation using machine learning becomes\nfeasible. In this work, we present the use of deep learning techniques to\npredict three important star formation properties -- stellar mass, star\nformation rate and dust luminosity. We characterise the performance of our deep\nlearning models through comparisons with outputs from a standard stellar\npopulation synthesis code." }, { "anchor": "Classification of field dwarfs and giants in RAVE and its use in stellar\n stream detection: An efficient separation between dwarfs and giants in surveys of bright stars\nis important, especially for studies in which distances are estimated through\nphotometric parallax relations. We use the available spectroscopic log g\nestimates from the second RAVE data release (DR2) to assign each star a\nprobability for being a dwarf or subgiant/giant based on mixture model fits to\nthe log g distribution in different color bins. We further attempt to use these\nstars as a labeled training set in order to classify stars which lack log g\nestimates into dwarfs and giants with a SVM algorithm. We assess the\nperformance of this classification against different choices of the input\nfeature vector. In particular, we use different combinations of reduced proper\nmotions, 2MASS JHK, DENIS IJK and USNO-B B2R2 apparent magnitudes. Our study\nshows that -- for our color ranges -- the infrared bands alone provide no\nrelevant information to separate dwarfs and giants. Even when optical bands and\nreduced proper motions are added, the fraction of true giants classified as\ndwarfs (the contamination) remains above 20%.\n Using only the dwarfs with available spectroscopic log g and distance\nestimates (the latter from Breddels et al. 2010), we then repeat the stream\nsearch by Klement, Fuchs & Rix (2008, KFR08), which assumed all stars were\ndwarfs and claimed the discovery of a new stellar stream at V = -160 km/s in a\nsample of 7015 stars from RAVE DR1. Our re-analysis of the pure DR2 dwarf\nsample exhibits an overdensity of 5 stars at the phase-space position of the\nKFR08 stream, with a metallicity distribution that appears inconsistent with\nthat of stars at comparably low rotational velocities. Compared to several\nsmooth Milky Way models, the mean standardized deviation of the KFR08 stream is\nonly marginal at 1.6$\\pm$0.4... (abbreviated)", "positive": "Monitoring observations of 6.7 GHz methanol masers: We report results of 6.7 GHz methanol maser monitoring of 139 star-forming\nsites with the Torun 32 m radio telescope from June 2009 to February 2013. The\ntargets were observed at least once a month, with higher cadences of 2-4\nmeasurements per week for circumpolar objects. Nearly 80 percent of the sources\ndisplay variability greater than 10 per cent on a time-scale between a week and\na few years but about three quarters of the sample have only 1-3 spectral\nfeatures which vary significantly. Irregular intensity fluctuation is the\ndominant type of variability and only nine objects show evidence for cyclic\nvariations with periods of 120 to 416 d. Synchronised and anti-correlated\nvariations of maser features are detected in four sources with a disc-like\nmorphology. Rapid and high amplitude bursts of individual features are seen on\n3-5 occasions in five sources. Long (>50 d to 20 months) lasting bursts are\nobserved mostly for individual or groups of features in 19 sources and only one\nsource experienced a remarkable global flare. A few flaring features display a\nstrong anti-correlation between intensity and line-width that is expected for\nunsaturated amplification. There is a weak anti-correlation between the maser\nfeature luminosity and variability measure, i.e. maser features with low\nluminosity tend to be more variable than those with high luminosity. The\nanalysis of the spectral energy distribution and continuum radio emission\nreveals that the variability of the maser features increases when the\nbolometric luminosity and Lyman flux of the exciting object decreases. Our\nresults support the concept of a major role for infrared pumping photons in\ntriggering outburst activity of maser emission." }, { "anchor": "Deep X-ray spectroscopy and imaging of the Seyfert 2 galaxy, ESO\n 138-G001: We present a spectral and imaging analysis of the XMM-Newton and Chandra\nobservations of the Seyfert 2 galaxy ESO138-G001, with the aim of\ncharacterizing the circumnuclear material responsible for the soft (0.3-2.0\nkeV) and hard (5-10 keV) X-ray emission. We confirm that the source is absorbed\nby Compton-thick gas. However, if a self-consistent model of reprocessing from\ncold toroidal material is used (MYTorus), a possible scenario requires the\nabsorber to be inhomogenous, its column density along the line of sight being\nlarger than the average column density integrated over all lines- of-sight\nthrough the torus. The iron emission line may be produced by moderately ionised\niron (FeXII-FeXIII), as suggested by the shifted centroid energy and the low\nK{\\beta}/K{\\alpha} flux ratio. The soft X-ray emission is dominated by emission\nfeatures, whose main excitation mechanism appears to be photoionisation, as\nconfirmed by line diagnostics and the use of self-consistent models (CLOUDY).", "positive": "Compact star-forming galaxies preferentially quenched to become PSBs in\n $z<1$ clusters: We analyse the structure of galaxies with high specific star formation rate\n(SSFR) in cluster and field environments in the redshift range $0.5 \\tau_z$) perturbations excite stronger\nbreathing and bending modes, respectively, although the response to very slow\nperturbations is exponentially suppressed. For encounters with satellite\ngalaxies, this translates to more distant and more perpendicular encounters\ntriggering stronger bending modes. We compute the direct response of the Milky\nWay disk to several of its satellite galaxies, and find that recent encounters\nwith all of them excite bending modes in the Solar neighborhood. The encounter\nwith Sagittarius triggers a response that is at least $1-2$ orders of magnitude\nlarger than that due to any other satellite, including the Large Magellanic\nCloud. We briefly discuss how ignoring the presence of a dark matter halo and\nthe self-gravity of the response might impact our conclusions." }, { "anchor": "Laboratory rotational spectroscopy of isotopic acetone,\n CH$_3^{13}$C(O)CH$_3$ and $^{13}$CH$_3$C(O)CH$_3$, and astronomical search in\n Sagittarius B2(N2): We want to study the rotational spectra of CH$_3^{13}$C(O)CH$_3$ and\n$^{13}$CH$_3$C(O)CH$_3$ and search for them in Sagittarius B2(N2). We\ninvestigated the laboratory rotational spectrum of isotopically enriched\nCH$_3^{13}$C(O)CH$_3$ between 40 GHz and 910 GHz and of acetone between 36 GHz\nand 910 GHz in order to study $^{13}$CH$_3$C(O)CH$_3$ in natural isotopic\ncomposition. In addition, we searched for emission lines produced by these\nspecies in a molecular line survey of Sagittarius B2(N) carried out with ALMA.\nDiscrepancies between predictions of the main isotopic species and the ALMA\nspectrum prompted us to revisit the rotational spectrum of this isotopolog. We\nassigned 9711 new transitions of CH$_3^{13}$C(O)CH$_3$ and 63 new transitions\nof $^{13}$CH$_3$C(O)CH$_3$ in the laboratory spectra. More than 1000 additional\nlines were assigned for the main isotopic species. We modeled the ground state\ndata of all three isotopologs satisfactorily with the ERHAM program. We find\nthat models of the torsionally excited states $v _{12} = 1$ and $v _{17} = 1$\nof CH$_3$C(O)CH$_3$ improve only marginally. No transition of\nCH$_3^{13}$C(O)CH$_3$ is clearly detected toward the hot molecular core Sgr\nB2(N2). However, we report a tentative detection of $^{13}$CH$_3$C(O)CH$_3$\nwith a $^{12}$C/$^{13}$C isotopic ratio of 27 that is consistent with the ratio\npreviously measured for alcohols in this source. Several dozens of transitions\nof both torsional states of the main isotopolog are detected as well. Our\npredictions of CH$_3^{13}$C(O)CH$_3$ and CH$_3$C(O)CH$_3$ are reliable into the\nterahertz region. The spectrum of $^{13}$CH$_3$C(O)CH$_3$ should be revisited\nin the laboratory with an enriched sample. Transitions pertaining to the\ntorsionally excited states $v _{12} = 1$ and $v _{17} = 1$ of CH$_3$C(O)CH$_3$\ncould be identified unambiguously in Sagittarius B2(N2).", "positive": "The PAndAS view of the Andromeda satellite system - I. A Bayesian search\n for dwarf galaxies using spatial and color-magnitude information: We present a generic algorithm to search for dwarf galaxies in photometric\ncatalogs and apply it to the Pan-Andromeda Archaeological Survey (PAndAS). The\nalgorithm is developed in a Bayesian framework and, contrary to most\ndwarf-galaxy-search codes, makes use of both the spatial and color-magnitude\ninformation of sources in a probabilistic approach. Accounting for the\nsignificant contamination from the Milky Way foreground and from the structured\nstellar halo of the Andromeda galaxy, we recover all known dwarf galaxies in\nthe PAndAS footprint with high significance, even for the least luminous ones.\nSome Andromeda globular clusters are also recovered and, in one case,\ndiscovered. We publish a list of the 143 most significant detections yielded by\nthe algorithm. The combined properties of the 39 most significant isolated\ndetections show hints that at least some of these trace genuine dwarf galaxies,\ntoo faint to be individually detected. Follow-up observations by the community\nare mandatory to establish which are real members of the Andromeda satellite\nsystem. The search technique presented here will be used in an upcoming\ncontribution to determine the PAndAS completeness limits for dwarf galaxies.\nAlthough here tuned to the search of dwarf galaxies in the PAndAS data, the\nalgorithm can easily be adapted to the search for any localised overdensity\nwhose properties can be modeled reliably in the parameter space of any catalog." }, { "anchor": "A feather on the hat: Tracing the giant stellar stream around the\n Sombrero galaxy: Recent evidence of extremely metal-rich stars found in the Sombrero galaxy\n(M104) halo suggests that this galaxy has undergone a recent major merger with\na relatively massive galaxy. In this paper, we present wide-field deep images\nof the M104 outskirts obtained with a 18-cm amateur telescope with the purpose\nof detecting any coherent tidal features from this possible major merger. Our\nnew data, together with a model of the M104 inner halo and scattered light from\nstars around the field, allow us to trace for the first time the full path of\nthe stream on both sides of the disk of the galaxy. We fully characterize the\nring-like tidal structure and we confirm that this is the only observable\ncoherent substructure in the inner halo region. This result is in agreement\nwith the hypothesis that M104 was created by a wet major merger more than 3.5\nGyr ago that heated up the stellar population, blurring all old substructure.\nWe generated a set of numerical models that reproduce the formation of the\nobserved tidal structure. Our best fit model suggests the formation of this\nstream in the last 3 Gyr is independent of the wet major merger that created\nthe M104 system. Therefore, the formation of the tidal stream can put a\nconstraint on the time when the major merger occurred.", "positive": "Galaxies and Halos on Graph Neural Networks: Deep Generative Modeling\n Scalar and Vector Quantities for Intrinsic Alignment: In order to prepare for the upcoming wide-field cosmological surveys, large\nsimulations of the Universe with realistic galaxy populations are required. In\nparticular, the tendency of galaxies to naturally align towards overdensities,\nan effect called intrinsic alignments (IA), can be a major source of\nsystematics in the weak lensing analysis. As the details of galaxy formation\nand evolution relevant to IA cannot be simulated in practice on such volumes,\nwe propose as an alternative a Deep Generative Model. This model is trained on\nthe IllustrisTNG-100 simulation and is capable of sampling the orientations of\na population of galaxies so as to recover the correct alignments. In our\napproach, we model the cosmic web as a set of graphs, where the graphs are\nconstructed for each halo, and galaxy orientations as a signal on those graphs.\nThe generative model is implemented on a Generative Adversarial Network\narchitecture and uses specifically designed Graph-Convolutional Networks\nsensitive to the relative 3D positions of the vertices. Given (sub)halo masses\nand tidal fields, the model is able to learn and predict scalar features such\nas galaxy and dark matter subhalo shapes; and more importantly, vector features\nsuch as the 3D orientation of the major axis of the ellipsoid and the complex\n2D ellipticities. For correlations of 3D orientations the model is in good\nquantitative agreement with the measured values from the simulation, except for\nat very small and transition scales. For correlations of 2D ellipticities, the\nmodel is in good quantitative agreement with the measured values from the\nsimulation on all scales. Additionally, the model is able to capture the\ndependence of IA on mass, morphological type and central/satellite type." }, { "anchor": "The impact of spiral density waves on the distribution of Supernovae: We present an analysis of the impact of spiral density waves (DWs) on the\nradial and surface density distributions of supernovae (SNe) in host galaxies\nwith different arm classes. We use a well-defined sample of 269 relatively\nnearby, low-inclination, morphologically non-disturbed and unbarred Sa-Sc\ngalaxies from the Sloan Digital Sky Survey, hosting 333 SNe. Only for\ncore-collapse (CC) SNe, a significant difference appears when comparing their\nR25-normalized radial distributions in long-armed grand-design (LGD) versus\nnon-GD (NGD) hosts, with that in LGD galaxies being marginally inconsistent\nwith an exponential profile, while SNe Ia exhibit exponential surface density\nprofiles regardless of the arm class. Using a smaller sample of LGD galaxies\nwith estimated corotation radii (Rc), we show that the Rc-normalized surface\ndensity distribution of CC SNe indicates a dip at corotation. Although not\nstatistically significant, the high CC SNe surface density just inside and\noutside corotation may be the sign of triggered massive star formation by the\nDWs. Our results may, if confirmed with larger samples, support the large-scale\nshock scenario induced by spiral DWs in LGD galaxies, which predicts a higher\nstar formation efficiency around the shock fronts, avoiding the corotation\nregion.", "positive": "A global view of the inner accretion and ejection flow around super\n massive black holes: radiation driven accretion disk winds in a physical\n context: Understanding the physics and geometry of accretion and ejection around super\nmassive black holes (SMBHs) is important to understand the evolution of active\ngalactic nuclei (AGN) and therefore of the large scale structures of the\nUniverse. We aim at providing a simple, coherent, and global view of the\nsub-parsec accretion and ejection flow in AGN with varying Eddington ratio,\n$\\dot{m}$, and black hole mass, $M_{BH}$. We made use of theoretical insights,\nresults of numerical simulations, as well as UV and X-ray observations to\nreview the inner regions of AGN by including different accretion and ejection\nmodes, with special emphasis on the role of radiation in driving powerful\naccretion disk winds from the inner regions around the central SMBH. We propose\nfive $\\dot{m}$ regimes where the physics of the inner accretion and ejection\nflow around SMBHs is expected to change, and that correspond observationally to\nquiescent and inactive galaxies; low luminosity AGN (LLAGN); Seyferts and\nmini-broad absorption line quasars (mini-BAL QSOs); narrow line Seyfert 1\ngalaxies (NLS1s) and broad absorption line quasars (BAL QSOs); and\nsuper-Eddington sources. We include in this scenario radiation-driven disk\nwinds, which are strong in the high $\\dot{m}$, large $M_{BH}$ regime, and\npossibly present but likely weak in the moderate $\\dot{m}$, small $M_{BH}$\nregime. A great diversity of the accretion/ejection flows in AGN can be\nexplained to a good degree by varying just two fundamental properties: the\nEddington ratio $\\dot{m}$ and the black hole mass $M_{BH}$, and by the\ninclusion of accretion disk winds that can naturally be launched by the\nradiation emitted from luminous accretion disks." }, { "anchor": "Multiple Stellar Populations of Globular Clusters from Homogeneous\n Ca--CN--CH Photometry. V. $cn^\\prime_{\\rm JWL}$ as a Surrogate $cn_{\\rm JWL}$\n Index and NGC 6723: We introduce new color indices $cn^\\prime_{\\rm JWL}$ (= $Ca_{\\rm CTIO} -\nCa_{\\rm JWL}$) and $ch_{\\rm JWL}$ [=$(JWL43 - b) - (b-y)$], accurate\nphotometric measures of the CN band at $\\lambda$3883 and the CH G band,\nrespectively, in the study of the multiple populations (MPs) in globular\nclusters (GCs). Our photometric CN--CH relation for a large number of red-giant\nbranch (RGB) in M5 shows that the evolutions of the CN and CH between the CN-w\nand CN-s populations are not continuous. Armed with our new color indices, we\ninvestigate the MPs of NGC 6723, finding the RGB populational number ratio of\n$n$(CN-w):$n$(CN-s) $\\approx$ 35.5:64.5 ($\\pm$2.8) with no radial gradient.\nSimilar to other normal GCs with MPs, the helium abundance of the CN-s\npopulation inferred from the RGB bump magnitude is slightly enhanced by $\\Delta\nY$ = 0.012 $\\pm$ 0.012. Our $cn_{\\rm JWL}$ and $cn^\\prime_{\\rm JWL}$\ncolor-magnitude diagrams clearly show the discrete double AGB populations in\nNGC 6723, whose bright AGB populational number ratio is in marginally agreement\nwith that of the RGB stars within the statistical errors. Finally, our\nsynthetic $cn_{\\rm JWL}$ index is in good agreement with observations, except\nfor the CN-w asymptotic giant branch (AGB). To mitigate the discrepancy in the\nCN-w AGB may require a mild nitrogen enhancement and/or a large decrement in\nthe $^{12}$C/$^{13}$C ratio with respect to the bright RGB.", "positive": "Simulated Faraday Rotation Measures toward High Galactic Latitudes: We study the Faraday rotation measure (RM) due to the Galactic magnetic field\n(GMF) toward high Galactic latitudes. The RM arises from the global, regular\ncomponent as well as from the turbulent, random component of the GMF. We model\nthe former based on observations and the latter using the data of\nmagnetohydrodynamic turbulence simulations. For a large number of different GMF\nmodels, we produce mock RM maps around the Galactic poles and calculate various\nstatistical quantities with the RM maps. We find that the observed medians of\nRMs toward the north and south Galactic poles, $\\sim 0.0\\pm 0.5 {\\rm rad\nm^{-2}}$ and $\\sim +6.3\\pm 0.5 {\\rm rad m^{-2}}$, are difficult to explain with\nany of our many alternate GMF models. The standard deviation of observed RMs,\n$\\sim 9 {\\rm rad m^{-2}}$, is clearly larger than that of simulated RMs. The\nsecond-order structure function of observed RMs is substantially larger than\nthat of simulated RMs, especially at small angular scales. We discuss other\npossible contributions to RM toward high Galactic latitudes. Besides\nobservational errors and the intrinsic RM of background radio sources against\nwhich RM is observed, we suggest that the RM due to the intergalactic magnetic\nfield may account for a substantial fraction of the observed RM. Finally we\nnote that reproducing the observed medians may require additional components\nor/and structures of the GMF that are not present in our models." }, { "anchor": "MEGARA-IFU detection of extended HeII4686 nebular emission in the\n central region of NGC1569 and its ionization budget: We here report the detection of extended HeII4686 nebular emission in the\ncentral region of NGC1569 using the integral field spectrograph MEGARA at the\n10.4-m Gran Telescopio Canarias. The observations cover a Field of View (FoV)\nof 12.5 arcsec x 11.3 arcsec at seeing-limited spatial resolution of ~15 pc and\nat a spectral resolution of R=6000 in the wavelength range 4330--5200 Angstrom.\nThe emission extends over a semi-circular arc of ~40 pc width and ~150 pc\ndiameter around the super star cluster A (SSC-A). The Av derived using Balmer\ndecrement varies from the Galactic value of 1.6 mag to a maximum of ~4.5 mag,\nwith a mean value of 2.65+/-0.60 mag. We infer 124+/-11 Wolf-Rayet (WR) stars\nin SSC-A using the HeII4686 broad feature and Av=2.3 mag. The He+ ionizing\nphoton rate from these WR stars is sufficient to explain the luminosity of the\nHeII4686 nebula. The observationally-determined total He+ and H0 ionizing\nphoton rates, their ratio, and the observed number of WR stars in SSC-A are all\nconsistent with the predictions of simple stellar population models at an age\nof 4.0+/-0.5 Myr, and mass of (5.5+/-0.5)x10^5 Msun. Our observations reinforce\nthe absence of WR stars in SSC-B, the second most massive cluster in the FoV.\nNone of the other locations in our FoV where HeII4686 emission has been\nreported from narrow-band imaging observations contain WR stars.", "positive": "The LOFAR view of massive early-type galaxies: Transition from radio AGN\n to host emission: We extend the study of the radio emission in early-type galaxies (ETGs) in\nthe nearby Universe (recession velocity <7,500 km/s) as seen by the 150 MHz\nLow-Frequency ARray (LOFAR) observations and extend the sample from giant ETGs\nto massive (~6x10^10 - 3x10^11 solar masses) ETGs (mETGS) with -25 < MK <\n-23.5. Images from the second data release of the LOFAR Two-metre Sky Survey\nwere available for 432 mETGs, 48% of which are detected above a typical\nluminosity of ~3x10^20 W/Hz. Most (85%) of the detected sources are compact,\nwith sizes <4 kpc. The radio emission of 31 mETGs is extended on scales ranging\nfrom 2 to 180 kpc (median 12 kpc). In several cases, it is aligned with the\nhost galaxy. We set a limit of ~1% to the fraction of remnant or restarted\nobjects, which is ~16% of the extended sources.\n We found that the properties of the radio sources are connected with the\nstellar mass of the ETGs (the median radio power, the fraction of extended\nradio sources, and the link with the large-scale environment). However, these\nresults only describe statistical trends because the radio properties of\nsources of similar stellar mass and environment show a large spread of radio\nproperties. These trends break at the lowest host luminosities (MK>-24.5). This\neffect is strengthened by the analysis of even less massive ETGs, with -23.5 <\nMK < -21.5. This suggests that at a mass of ~2x10^11 solar masses, a general\ntransition occurs from radio emission produced from radio-loud active galactic\nnuclei (AGN) to processes related to the host galaxy and (or) radio quiet AGN.\nAt this luminosity, a transition in the stellar surface brightness profile also\noccurs from Sersic galaxies to those with a depleted stellar core, the\nso-called core galaxies. This finding is in line with previous results that\nindicated that only core galaxies host radio-loud AGN." }, { "anchor": "The Lyman Continuum Escape Survey: Ionizing Radiation from [O\n III]-Strong Sources at a Redshift of 3.1: We present results from the LymAn Continuum Escape Survey (LACES), a Hubble\nSpace Telescope (HST) program designed to characterize the ionizing radiation\nemerging from a sample of Lyman alpha emitting galaxies at redshift $z\\simeq\n3.1$. As many show intense [O III] emission characteristic of $z>6.5$\nstar-forming galaxies, they may represent valuable low redshift analogs of\ngalaxies in the reionization era. Using HST Wide Field Camera 3 / UVIS $F336W$\nto image Lyman continuum emission, we investigate the escape fraction of\nionizing photons in this sample. For 61 sources, of which 77% are\nspectroscopically confirmed and 53 have measures of [O III] emission, we detect\nLyman continuum leakage in 20%, a rate significantly higher than is seen in\nindividual continuum-selected Lyman break galaxies. We estimate there is a 98%\nprobability that $\\leq 2$ of our detections could be affected by foreground\ncontamination. Fitting multi-band spectral energy distributions (SEDs) to take\naccount of the varying stellar populations, dust extinctions and metallicities,\nwe derive individual Lyman continuum escape fractions corrected for foreground\nintergalactic absorption. We find escape fractions of 15 to 60% for individual\nobjects, and infer an average 20% escape fraction by fitting composite SEDs for\nour detected samples. Surprisingly however, even a deep stack of those sources\nwith no individual $F336W$ detections provides a stringent upper limit on the\naverage escape fraction of less than 0.5%. We examine various correlations with\nsource properties and discuss the implications in the context of the popular\npicture that cosmic reionization is driven by such compact, low metallicity\nstar-forming galaxies.", "positive": "Searching for z > 6.5 Analogs Near the Peak of Cosmic Star Formation: Strong [OIII]$\\lambda\\lambda$4959,5007+H$\\beta$ emission appears to be\ntypical in star-forming galaxies at z > 6.5. As likely contributors to cosmic\nreionization, these galaxies and the physical conditions within them are of\ngreat interest. At z > 6.5, where Ly$\\alpha$ is greatly attenuated by the\nintergalactic medium, rest-UV metal emission lines provide an alternative\nmeasure of redshift and also constraints on the physical properties of\nstar-forming regions and massive stars. We present the first statistical sample\nof rest-UV line measurements in z $\\sim$ 2 galaxies selected as analogs of\nthose in the reionization era based on [OIII]$\\lambda\\lambda$4959,5007 EW or\nrest-frame U-B color. Our sample is drawn from the 3D-HST Survey and spans the\nredshift range 1.36 $\\leqslant$ z $\\leqslant$ 2.49. We find that the median\nLy$\\alpha$ and CIII]$\\lambda\\lambda$1907,1909 EWs of our sample are\nsignificantly greater than those of z $\\sim$ 2 UV-continuum-selected\nstar-forming galaxies. Measurements from both individual and composite spectra\nindicate a monotonic, positive correlation between CIII] and [OIII], while a\nlack of trend is observed between Ly$\\alpha$ and [OIII] at [OIII] EW <\n1000$\\unicode{x212B}$. At higher [OIII] EW, extreme Ly$\\alpha$ emission starts\nto emerge. Using stacked spectra, we find that Ly$\\alpha$ and CIII] are\nsignificantly enhanced in galaxies with lower metallicity. Two objects in our\nsample appear comparable to z > 6.5 galaxies with exceptionally strong rest-UV\nmetal line emission. These objects have significant\nCIV$\\lambda\\lambda$1548,1550, HeII$\\lambda$1640, and\nOIII]$\\lambda\\lambda$1661,1665 emission in addition to intense Ly$\\alpha$ or\nCIII]. Detailed characterization of these lower-redshift analogs provides\nunique insights into the physical conditions in z > 6.5 star-forming regions,\nmotivating future observations of reionization-era analogs at lower redshifts." }, { "anchor": "Stellar feedback impact on the ionized gas kinematics in the dwarf\n galaxy Sextans B: We investigated the ionised and atomic gas kinematics and excitation state in\nthe central region of ongoing star formation of the nearby low-metallicity\ndwarf galaxy Sextans B. The analysis is based on the new observations performed\nin Ha emission line with high resolution ($R \\sim 16000$) scanning Fabry-Perot\ninterferometer at the 6-m BTA SAO RAS telescope, and on the long-slit spectral\nobservations at the 9.2-m SALT and 2.5-m CMO SAI MSU telescopes. Strong\nnon-circular gas motions detected in the studied regions probably resulted from\nthe off-plane gas motions and impact of stellar feedback. We identified six\nregions of elevated Ha velocity dispersion, five of which exhibit asymmetric or\ntwo-component Ha line profiles. Three of these regions are young ($<1.1$ Myr)\nexpanding ($V_{\\rm exp} \\sim 25-50\\ {\\rm km\\ s^{-1}}$) superbubbles. We argue\nthat at least three regions in the galaxy could be supernova remnants. We\nconclude that supernovae feedback is the dominant source of energy for\nsuperbubbles in Sextans B, which is expected for such a low metallicity,\nalthough we cannot rule out a strong impact of pre-supernova feedback for one\nsuperbubble.", "positive": "The StEllar Counterparts of COmpact high velocity clouds (SECCO) survey.\n II. Sensitivity of the survey and an Atlas of Synthetic Dwarf Galaxies: SECCO is a survey devoted to the search for stellar counterparts within Ultra\nCompact High Velocity Clouds. In this contribution we present the results of a\nset of simulations aimed at the quantitative estimate of the sensitivity of the\nsurvey as a function of the total luminosity, size and distance of the stellar\nsystems we are looking for. For all our synthetic galaxies we assumed an\nexponential surface brightness profile and an old and metal-poor population.\nThe synthetic galaxies are simulated both on the images and on the photometric\ncatalogs, taking into account all the observational effects. In the fields\nwhere the available observational material is of the top quality we detect\nsynthetic galaxies as >=5 sigma over-densities of resolved stars down to\nmuV,h=30.0 mag/arcsec2, for D<=1.5 Mpc, and down to muV,h~29.5 mag/arcsec2, for\nD<=2.5 Mpc. In the field with the worst observational material of the whole\nsurvey we detect synthetic galaxies with muV,h<=28.8 mag/arcsec2 out to D<=1.0\nMpc, and those with muV,h<=27.5 mag/arcsec2 out to D<=2.5 Mpc. Dwarf galaxies\nwith MV=-10, with sizes in the range spanned by known dwarfs, are detected by\nvisual inspection of the images up to D=5 Mpc independently of the image\nquality. In the best quality images dwarfs are partially resolved into stars up\nto D=3.0 Mpc, and completely unresolved at D=5 Mpc. As an independent test of\nthe sensitivity of our images to low surface brightness galaxies we report on\nthe detection of several dwarf spheroidal galaxies probably located in the\nVirgo cluster with MV<=-8.0 and muV,h<=26.8 mag/arcsec2. The nature of the\npreviously discovered SECCO 1 stellar system, also likely located in the Virgo\ncluster, is re-discussed in comparison with these dwarfs. While specific for\nthe SECCO survey, our study may also provide general guidelines for detection\nof faint stellar systems with 8m class telescopes." }, { "anchor": "REMAP: Determination of the inner edge of the dust torus in AGN by\n measuring time delays: Active galactic nuclei (AGN) are high luminosity sources powered by accretion\nof matter onto SMBHs located at the centres of galaxies. The SMBH is surrounded\nby a broad emission line region (BLR) and a dusty torus. It is difficult to\nstudy the extent of the dusty torus as the central region of AGN is not\nresolvable using any conventional imaging techniques available today. Though,\ncurrent IR interferometric techniques could in principle resolve the torus in\nnearby AGN, it is very expensive and limited to few bright and nearby AGN. A\nmore feasible alternative to the interferometric technique to find the extent\nof the dusty torus in AGN is the technique of reverberation mapping (RM). REMAP\n(REverberation Mapping of AGN Program) is a long term photometric monitoring\nprogram being carried out using the 2 m HCT operated by the IIA, Bangalore,\naimed at measuring the torus size in many AGN using the technique of RM. It\ninvolves accumulation of suitably long and well sampled light curves in the\noptical and near-infrared bands to measure the time delays between the light\ncurves in different wavebands. These delays are used to determine the radius of\nthe inner edge of the dust torus. REMAP was initiated in the year 2016 and\nsince then about one hour of observing time once every five days (weather\npermitting) has been allocated at the HCT. Our initial sample carefully\nselected for this program consists of a total of 8 sources observable using the\nHCT. REMAP has resulted in the determination of the extent of the inner edge of\nthe dusty torus in one AGN namely H0507+164. Data accumulation for the second\nsource is completed and observations on the third source are going on. We will\noutline the motivation of this observational program, the observational\nstrategy that is followed, the analysis procedures adopted for this work and\nthe results obtained from this program till now.", "positive": "A New Measurement of the Mean Transmitted Flux in the Lyman-alpha and\n Lyman-beta Forest: We present new measurements of the mean transmitted flux in the hydrogen\nLyman-alpha and Lyman-beta forest using 27,008 quasar spectra from the\nFourteenth Data Release (DR14) of the Extended Baryon Oscillation Spectroscopic\nSurvey (eBOSS). Individual spectra are first combined into 16 composites with\nmean redshifts in the range of 2.8 < z < 4.9. We then apply Markov Chain Monte\nCarlo (MCMC) inference to produce a piecewise fit of the effective\n{\\tau_{Ly\\alpha}} (corrected for metal lines and optically thick absorptions)\nand relative {\\Delta}{\\tau_{Ly\\beta}} optical depths. A detailed evaluation of\nour large data set shows a systematic offset towards lower values of\n{\\tau_{Ly\\alpha}} compared to recent results by Kamble et al. (2020) based on\nSDSS DR12." }, { "anchor": "Surrogate modelling the Baryonic Universe II: on forward modelling the\n colours of individual and populations of galaxies: Among the properties shaping the light of a galaxy, the star formation\nhistory (SFH) is one of the most challenging to model due to the variety of\ncorrelated physical processes regulating star formation. In this work, we\nleverage the stellar population synthesis model FSPS, together with SFHs\npredicted by the hydrodynamical simulation IllustrisTNG and the empirical model\nUNIVERSEMACHINE, to study the impact of star formation variability on galaxy\ncolours. We start by introducing a model-independent metric to quantify the\nburstiness of a galaxy formation model, and we use this metric to demonstrate\nthat UNIVERSEMACHINE predicts SFHs with more burstiness relative to\nIllustrisTNG. Using this metric and principal component analysis, we construct\nfamilies of SFH models with adjustable variability, and we show that the\nprecision of broad-band optical and near-infrared colours degrades as the level\nof unresolved short-term variability increases. We use the same technique to\ndemonstrate that variability in metallicity and dust attenuation presents a\npractically negligible impact on colours relative to star formation\nvariability. We additionally provide a model-independent fitting function\ncapturing how the level of unresolved star formation variability translates\ninto imprecision in predictions for galaxy colours; our fitting function can be\nused to determine the minimal SFH model that reproduces colours with some\ntarget precision. Finally, we show that modelling the colours of individual\ngalaxies with percent-level precision demands resorting to complex SFH models,\nwhile producing precise colours for galaxy populations can be achieved using\nmodels with just a few degrees of freedom.", "positive": "Herschel observations of EXtra-Ordinary Sources: Analysis of the HIFI\n 1.2 THz Wide Spectral Survey Toward Orion KL I. Methods: We present a comprehensive analysis of a broad band spectral line survey of\nthe Orion Kleinmann-Low nebula (Orion KL), one of the most chemically rich\nregions in the Galaxy, using the HIFI instrument on board the Herschel Space\nObservatory. This survey spans a frequency range from 480 to 1907 GHz at a\nresolution of 1.1 MHz. These observations thus encompass the largest spectral\ncoverage ever obtained toward this high-mass star-forming region in the sub-mm\nwith high spectral resolution, and include frequencies $>$ 1 THz where the\nEarth's atmosphere prevents observations from the ground. In all, we detect\nemission from 39 molecules (79 isotopologues). Combining this dataset with\nground based mm spectroscopy obtained with the IRAM 30 m telescope, we model\nthe molecular emission from the mm to the far-IR using the XCLASS program which\nassumes local thermodynamic equilibrium (LTE). Several molecules are also\nmodeled with the MADEX non-LTE code. Because of the wide frequency coverage,\nour models are constrained by transitions over an unprecedented range in\nexcitation energy. A reduced $\\chi^{2}$ analysis indicates that models for most\nspecies reproduce the observed emission well. In particular, most complex\norganics are well fit by LTE implying gas densities are high ($>$10$^6$\ncm$^{-3}$) and excitation temperatures and column densities are well\nconstrained. Molecular abundances are computed using H$_{2}$ column densities\nalso derived from the HIFI survey. The distribution of rotation temperatures,\n$T_{\\rm rot}$, for molecules detected toward the hot core is significantly\nwider than the compact ridge, plateau, and extended ridge $T_{\\rm rot}$\ndistributions, indicating the hot core has the most complex thermal structure." }, { "anchor": "The loss of the intra-cluster medium in globular clusters: Stars in globular clusters (GCs) lose a non negligible amount of mass during\ntheir post-main sequence evolution. This material is then expected to build up\na substantial intra-cluster medium (ICM) within the GC. However, the observed\ngas content in GCs is a couple of orders of magnitude below these expectations.\nHere we follow the evolution of this stellar wind material through\nhydrodynamical simulations to attempt to reconcile theoretical predictions with\nobservations. We test different mechanisms proposed in the literature to clear\nout the gas such as ram-pressure stripping by the motion of the GC in the\nGalactic halo medium and ionisation by UV sources. We use the code ramses to\nrun 3D hydrodynamical simulations to study for the first time the ICM evolution\nwithin discretised multi-mass GC models including stellar winds and full\nradiative transfer. We find that the inclusion of both ram-pressure and\nionisation is mandatory to explain why only a very low amount of ionised gas is\nobserved in the core of GCs. The same mechanisms operating in ancient GCs that\nclear the gas could also be efficient at younger ages, meaning that young GCs\nwould not be able to retain gas and form multiple generations of stars as\nassumed in many models to explain \"multiple populations\". However, this rapid\nclearing of gas is consistent with observations of young massive clusters.", "positive": "The Star Formation and AGN luminosity relation: Predictions from a\n semi-analytical model: In a Universe where AGN feedback regulates star formation in massive\ngalaxies, a strong correlation between these two quantities is expected. If the\ngas causing star formation is also responsible for feeding the central black\nhole, then a positive correlation is expected. If powerful AGNs are responsible\nfor the star formation quenching, then a negative correlation is expected.\nObservations so far have mainly found a mild correlation or no correlation at\nall (i.e. a flat relation between star formation rate (SFR) and AGN\nluminosity), raising questions about the whole paradigm of \"AGN feedback\". In\nthis paper, we report the predictions of the GALFORM semi-analytical model,\nwhich has a very strong coupling between AGN activity and quenching of star\nformation. The predicted SFR-AGN luminosity correlation appears negative in the\nlow AGN luminosity regime, where AGN feedback acts, but becomes strongly\npositive in the regime of the brightest AGN. Our predictions reproduce\nreasonably well recent observations by Rosario et al., yet there is some\ndiscrepancy in the normalisation of the correlation at low luminosities and\nhigh redshifts. Though this regime could be strongly influenced by\nobservational biases, we argue that the disagreement could be ascribed to the\nfact that GALFORM neglects AGN variability effects. Interestingly, the galaxies\nthat dominate the regime where the observations imply a weak correlation are\nmassive early-type galaxies that are subject to AGN feedback. Nevertheless,\nthese galaxies retain high enough molecular hydrogen contents to maintain\nrelatively high star formation rates and strong infrared emission." }, { "anchor": "Space and velocity distributions of Galactic isolated old Neutron stars: I present the results of Monte-Carlo orbital simulations of Galactic Neutron\nStars (NSs). The simulations take into account the up-to-date observed NS space\nand velocity distributions at birth, and account for their formation rate. I\nsimulate two populations of NSs. Objects in the first population were born in\nthe Galactic disk at a constant rate, in the past 12 Gyr. Those in the second\npopulation were formed simultaneously 12 Gyr ago in the Galactic bulge. I\nassume that the NSs born in the Galactic disk comprise 40% of the total NS\npopulation. Since the initial velocity distribution of NSs is not well known, I\nrun two sets of simulations, each containing 3x10^6 simulated NSs. One set\nutilizes a bimodal initial velocity distribution and the other a unimodal\ninitial velocity distribution, both are advocated based on pulsars\nobservations. In light of recent observational results, I discuss the effect of\ndynamical heating by Galactic structure on NS space and velocity distributions\nand show it can be neglected. I present catalogue of simulated NS space and\nvelocity vectors in the current epoch, and catalogue of positions, distances\nand proper motions of simulated NSs, relative to the Sun. Assuming there are\n10^9 NSs in the Galaxy, I find that in the solar neighborhood the density of\nNSs is about 2-4x10^-4 pc^-3 and their scale height is about 0.3-0.6 kpc\n(depending on the adopted initial velocity distribution). These catalogue can\nbe used to test the hypothesis that some radio transients are related to these\nobjects.", "positive": "Neutral interstellar helium parameters based on IBEX-Lo observations and\n test particle calculations: Neutral Interstellar Helium (NISHe) is almost unaffected at the heliospheric\ninterface with the interstellar medium and freely enters the solar system. It\nprovides some of the best information on the characteristics of the\ninterstellar gas in the Local Interstellar Cloud. The Interstellar Boundary\nExplorer (IBEX) is the second mission to directly detect NISHe. We present a\ncomparison between recent IBEX NISHe observations and simulations carried out\nusing a well-tested quantitative simulation code. Simulation and observation\nresults compare well for times when measured fluxes are dominated by NISHe (and\ncontributions from other species are small). Differences between simulations\nand observations indicate a previously undetected secondary population of\nneutral helium, likely produced by interaction of interstellar helium with\nplasma in the outer heliosheath. Interstellar neutral parameters are\nstatistically different from previous in situ results obtained mostly from the\nGAS/Ulysses experiment, but they do agree with the local interstellar flow\nvector obtained from studies of interstellar absorption: the newly-established\nflow direction is ecliptic longitude 79.2 deg, latitude -5.1 deg, the velocity\nis \\sim 22.8 km/s, and the temperature is 6200 K. These new results imply a\nmarkedly lower absolute velocity of the gas and thus significantly lower\ndynamic pressure on the boundaries of the heliosphere and different orientation\nof the Hydrogen Deflection Plane compared to prior results from Ulysses. A\ndifferent orientation of this plane also suggests a new geometry of the\ninterstellar magnetic field and the lower dynamic pressure calls for a\ncompensation by other components of the pressure balance, most likely a higher\ndensity of interstellar plasma and strength of interstellar magnetic field." }, { "anchor": "Quasar Rain: the Broad Emission Line Region as Condensations in the Warm\n Accretion Disk Wind: The origin of the broad emission line region (BELR) in quasars and active\ngalactic nuclei is still unclear. I propose that condensations form in the\nwarm, radiation pressure driven, accretion disk wind of quasars creating the\nBEL clouds and uniting them with the other two manifestations of cool, 10,000\nK, gas in quasars, the low ionization phase of the warm absorbers (WAs) and the\nclouds causing X-ray eclipses. The cool clouds will condense quickly (days to\nyears), before the WA outflows reach escape velocity (which takes months to\ncenturies). Cool clouds form in equilibrium with the warm phase of the wind\nbecause the rapidly varying X-ray quasar continuum changes the force\nmultiplier, causing pressure waves to move gas into stable locations in\npressure-temperature space. The narrow range of 2-phase equilibrium densities\nmay explain the scaling of the BELR size with the square root of luminosity,\nwhile the scaling of cloud formation timescales could produce the Baldwin\neffect. These dense clouds have force multipliers of order unity and so cannot\nbe accelerated to escape velocity. They fall back on a dynamical timescale\n(months to centuries), producing an inflow that rains down toward the central\nblack hole. As they soon move at Mach ~40 with respect to the WA outflow, these\n'raindrops' will be rapidly destroyed within months. This rain of clouds may\nproduce the elliptical BELR orbits implied by velocity resolved reverberation\nmapping in some objects, and can explain the opening angle and destruction\ntimescale of the narrow 'cometary' tails of the clouds seen in X-ray eclipse\nobservations. Some consequences and challenges of this 'quasar rain' model are\npresented along with several avenues for theoretical investigation.", "positive": "Theoretical modelling of two-component molecular discs in spiral\n galaxies: As recent observations of the molecular discs in spiral galaxies point to the\nexistence of a diffuse, low-density thick molecular disc along with the\nprominent thin one, we investigate the observational signatures of this thick\ndisc by theoretically modelling two-component molecular discs in a sample of\neight nearby spiral galaxies. Assuming a prevailing hydrostatic equilibrium, we\nset up and solved the joint Poisson's-Boltzmann equation to estimate the\nthree-dimensional distribution of the molecular gas and the molecular scale\nheight in our sample galaxies. The molecular scale height in a two-component\nmolecular disc is found to vary between $50-300$ pc, which is higher than what\nis found in a single-component disc. We find that this scale height can vary\nsignificantly depending on the assumed thick disc molecular gas fraction. We\nalso find that the molecular gas flares as a function of the radius and follows\na tight exponential law with a scale length of $\\left(0.48 \\pm 0.01 \\right)\nr_{25}$. We used the density solutions to produce the column density maps and\nspectral cubes to examine the ideal observing conditions to identify a thick\nmolecular disc in galaxies. We find that unless the molecular disc is an\nedge-on system and imaged with a high spatial resolution ($\\lesssim 100$ pc),\nit is extremely hard to identify a thick molecular disc in a column density\nmap. The spectral analysis further reveals that at moderate to high inclination\n($i \\gtrsim 40^o$), spectral broadening can fictitiously introduce the\nsignatures of a two-component disc into the spectral cube of a single-component\ndisc. Hence, we conclude that a low inclination molecular disc imaged with high\nspatial resolution would serve as the ideal site for identifying the thick\nmolecular disc in galaxies." }, { "anchor": "The Gas Properties of the W3 GMC: A HARP study: We present 12CO, 13CO and C18O J=3-2 maps of the W3 GMC made at the James\nClerk Maxwell Telescope. We combine these observations with Five Colleges Radio\nAstronomy Observatory CO J=1-0 data to produce the first map of molecular-gas\ntemperatures across a GMC and the most accurate determination of the mass\ndistribution in W3 yet obtained. We measure excitation temperatures in the part\nof the cloud dominated by triggered star formation (the High Density Layer,\nHDL) of 15-30 K, while in the rest of the cloud, which is relatively unaffected\nby triggering (Low Density Layer, LDL), the excitation temperature is generally\nless than 12 K. We identify a temperature gradient in the HDL which we\nassociate with an age sequence in the embedded massive star-forming regions. We\nmeasure the mass of the cloud to be 4.4+/-0.4 x 10^5 solar masses, in agreement\nwith previous estimates. Existing sub-mm continuum data are used to derive the\nfraction of gas mass in dense clumps as a function of position in the cloud.\nThis fraction, which we interpret as a Clump Formation Efficiency (CFE), is\nsignificantly enhanced across the HDL, probably due to the triggering. Finally,\nwe measure the 3D rms Mach Number as a function of position and find a\ncorrelation between the Mach number and the CFE within the HDL only. This\ncorrelation is interpreted as due to feedback from the newly-formed stars and a\nchange in its slope between the three main star-forming regions is construed as\nanother evolutionary effect. We conclude that triggering has affected the\nstar-formation process in the W3 GMC primarily by creating additional dense\nstructures that can collapse into stars. Any traces of changes in CFE due to\nadditional turbulence have since been overruled by the feedback effects of the\nstar-forming process itself.", "positive": "From galactic nuclei to the halo outskirts: tracing supermassive black\n holes across cosmic history and environments: We study the mass assembly and spin evolution of supermassive black holes\n(BHs) across cosmic time as well as the impact of gravitational recoil on the\npopulation of nuclear and wandering black holes (wBHs) by using the\nsemi-analytical model LGalaxies run on top of Millennium merger trees. We track\nspin changes that BHs experience during both coalescence events and gas\naccretion phases. For the latter, we assume that spin changes are coupled with\nthe bulge assembly. This assumption leads to predictions for the median spin\nvalues of z=0 BHs that depend on whether they are hosted by pseudobulges,\nclassical bulges or ellipticals, being a ~ 0.9, 0.7 and 0.4, respectively. The\noutcomes of the model display a good consistency with z<4 quasar luminosity\nfunctions and the z=0 BH mass function, spin values and black hole-bulge mass\ncorrelation. Regarding the wBHs, we assume that they can originate from both\nthe disruption of satellite galaxies (orphan wBH) and ejections due to\ngravitational recoils (ejected wBH). The model points to a number density of\nwBHs that increases with decreasing redshift, although this population is\nalways ~2 dex smaller than the one of nuclear black holes. At all redshifts,\nwBHs are typically hosted in M_{halo}>10^{13} M_{\\odot} and M_{stellar}>10^{10}\nM_{\\odot}, being orphan wBHs the dominant type. Besides, independently of\nredshift and halo mass, \\textit{ejected} wBHs inhabit the central regions\n(<0.3R_{200}) of the host DM halo, while orphan wBHs linger at larger scales\n(>0.5R_{200}). Finally, we find that gravitational recoils cause a progressive\ndepletion of nuclear BHs with decreasing redshift and stellar mass. Moreover,\nejection events lead to changes in the predicted local black hole-bulge\nrelation, in particular for BHs in pseudobulges, for which the relation is\nflattened at M_{bulge}>10^{10.2} M{\\odot} and the scatter increase up to ~3dex." }, { "anchor": "Fast, Collimated Outflow in the Western Nucleus of Arp 220: We present the first spatially and spectrally resolved image of the molecular\noutflow in the western nucleus of Arp\\,220. The outflow, seen in HCN~(1--0) by\nALMA, is compact and collimated, with extension $\\lesssim$ 120\\,pc. Bipolar\nmorphology emerges along the minor axis of the disk, with redshifted and\nblueshifted components reaching maximum inclination-corrected velocity of\n$\\sim\\,\\pm$\\,840\\,km\\,s$^{-1}$. The outflow is also seen in CO and continuum\nemission, the latter implying that it carries significant dust. We estimate a\ntotal mass in the outflow of $\\geqslant$\\,10$^{6}$\\,M$_{\\odot}$, a dynamical\ntime of $\\sim$\\,10$^{5}$\\,yr, and mass outflow rates of\n$\\geqslant55$\\,M$_{\\odot}$\\,yr$^{-1}$ and\n$\\geqslant\\,15$\\,M$_{\\odot}$\\,yr$^{-1}$ for the northern and southern lobes,\nrespectively. Possible driving mechanisms include supernovae energy and\nmomentum transfer, radiation pressure feedback, and a central AGN. The latter\ncould explain the collimated morphology of the HCN outflow, however we need\nmore complex theoretical models, including contribution from supernovae and\nAGN, to pinpoint the driving mechanism of this outflow.", "positive": "Keck/OSIRIS IFU Detection of a z $\\sim$ 3 Damped Lyman Alpha Host Galaxy: We present Keck/OSIRIS infrared IFU observations of the $z = $ 3.153 sub-DLA\nDLA2233+131, previously detected in absorption to a background quasar and\nstudied with single slit spectroscopy and PMAS integral field spectroscopy\n(IFU). We used the Laser Guide Star Adaptive Optics (LGSAO) and OSIRIS IFU to\nreduce the point-spread function of the background quasar to FWHM$\\sim$0.15\narcseconds and marginally resolve extended, foreground DLA emission. We detect\n[OIII]$\\lambda$5007 emission with a flux F$^{[OIII]\\lambda5007}$ =\n$(2.4\\pm0.5)\\times10^{-17}$ erg s$^{-1}$ cm$^{-2}$, as well as unresolved\n[OIII]$\\lambda$4959 and H$\\beta\\lambda$4861 emission. Using a composite\nspectrum over the emission region, we measure dynamical mass $\\sim$\n$3.1\\times10^9$ M$_{\\odot}$. We make several estimates of star formation rate\nusing [OIII]$\\lambda$5007 and H$\\beta\\lambda$4861 emission, and measure a star\nformation rate of $\\sim$ $7.1- 13.6$ M$_{\\odot}$ yr$^{-1}$. We map\n[OIII]$\\lambda$5007 and H$\\beta\\lambda$4861 emission and the corresponding\nvelocity fields to search for signs of kinematic structure. These maps allow\nfor a more detailed kinematic analysis than previously possible for this\ngalaxy. While some regions show slightly red and blue-shifted emission\nindicative of potential edge-on disk rotation, the data are insufficient to\nsupport this interpretation." }, { "anchor": "Sensitivity Estimation for Dark Matter Subhalos in Synthetic Gaia DR2\n using Deep Learning: The abundance of dark matter (DM) subhalos orbiting a host galaxy is a\ngeneric prediction of the cosmological framework, and is a promising way to\nconstrain the nature of DM. In this paper, we investigate the use of machine\nlearning-based tools to quantify the magnitude of phase-space perturbations\ncaused by the passage of DM subhalos. A simple binary classifier and an anomaly\ndetection model are proposed to estimate if stars or star particles close to DM\nsubhalos are statistically detectable in simulations. The simulated datasets\nare three Milky Way-like galaxies and nine synthetic Gaia DR2 surveys derived\nfrom these. Firstly, we find that the anomaly detection algorithm, trained on a\nsimulated galaxy with full 6D kinematic observables and applied on another\ngalaxy, is nontrivially sensitive to the DM subhalo population. On the other\nhand, the classification-based approach is not sufficiently sensitive due to\nthe extremely low statistics of signal stars for supervised training. Finally,\nthe sensitivity of both algorithms in the Gaia-like surveys is negligible. The\nenormous size of the Gaia dataset motivates the further development of scalable\nand accurate data analysis methods that could be used to select potential\nregions of interest for DM searches to ultimately constrain the Milky Way's\nsubhalo mass function, as well as simulations where to study the sensitivity of\nsuch methods under different signal hypotheses.", "positive": "Compact HI clouds from the GALFA-HI survey: The Galactic Arecibo L-band Feed Array HI (GALFA-HI) survey is mapping the\nentire Arecibo sky at 21-cm, over a velocity range of -700 to +700 km/s (LSR),\nat a velocity resolution of 0.18 km/s and a spatial resolution of 3.5 arcmin.\nThe unprecedented resolution and sensitivity of the GALFA-HI survey have\nresulted in the detection of numerous isolated, very compact HI clouds at low\nGalactic velocities, which are distinctly separated from the HI disk emission.\nIn the limited area of ~4600 deg$^2$ surveyed so far, we have detected 96 of\nsuch compact clouds. The detected clouds are cold with a median T$_{k,max}$\n(the kinetic temperature in the case in which there is no non-thermal\nbroadening) of 300 K. Moreover, these clouds are quite compact and faint, with\nmedian values of 5 arcmin in angular size, 0.75 K in peak brightness\ntemperature, and $5 \\times 10^{18}$ cm$^{-2}$ in HI column density. Most of the\nclouds deviate from Galactic rotation at the 20-30 km/s level, and a\nsignificant fraction show evidence for a multiphase medium and velocity\ngradients. No counterparts for these clouds were found in other wavebands. From\nthe modeling of spatial and velocity distributions of the whole compact cloud\npopulation, we find that the bulk of the compact clouds are related to the\nGalactic disk, and their distances are likely to be in the range of 0.1 to a\nfew kpc. We discuss various possible scenarios for the formation and\nmaintenance of this cloud population and its significance for Galactic ISM\nstudies." }, { "anchor": "Detecting the rapidly expanding outer shell of the Crab Nebula: where to\n look: We present a range of steady-state photoionization simulations, corresponding\nto different assumed shell geometries and compositions, of the unseen\npostulated rapidly expanding outer shell to the Crab Nebula. The properties of\nthe shell are constrained by the mass that must lie within it, and by limits to\nthe intensities of hydrogen recombination lines. In all cases the\nphotoionization models predict very strong emission from high ionization lines\nthat will not be emitted by the Crab's filaments, alleviating problems with\ndetecting these lines in the presence of light scattered from brighter parts of\nthe Crab. The NIR [Ne VI] $\\lambda$7.652 $\\mu$m line is a particularly good\ncase; it should be dramatically brighter than the optical lines commonly used\nin searches. The C IV $\\lambda1549\\AA$ doublet is predicted to be the strongest\nabsorption line from the shell, which is in agreement with HST observations. We\nshow that the cooling timescale for the outer shell is much longer than the age\nof the Crab, due to the low density. This means that the temperature of the\nshell will actually \"remember\" its initial conditions. However, the\nrecombination time is much shorter than the age of the Crab, so the predicted\nlevel of ionization should approximate the real ionization. In any case, it is\nclear that IR observations present the best opportunity to detect the outer\nshell and so guide future models that will constrain early events in the\noriginal explosion.", "positive": "Automatic detection of full ring galaxy candidates in SDSS: A full ring is a form of galaxy morphology that is not associated with a\nspecific stage on the Hubble sequence. Digital sky surveys can collect many\nmillions of galaxy images, and therefore even rare forms of galaxies are\nexpected to be present in relatively large numbers in image databases created\nby digital sky surveys. Sloan Digital Sky Survey (SDSS) data release (DR) 14\ncontains ~2.6*10^6 objects with spectra identified as galaxies. The method\ndescribed in this paper applied automatic detection to identify a set of 443\nring galaxy candidates, 104 of them were already included in the Buta + 17\ncatalogue of ring galaxies in SDSS, but the majority of the galaxies are not\nincluded in previous catalogues. Machine analysis cannot yet match the superior\npattern recognition abilities of the human brain, and even a small false\npositive rate makes automatic analysis impractical when scanning through\nmillions of galaxies. Reducing the false positive rate also increases the true\nnegative rate, and therefore the catalogue of ring galaxy candidates is not\nexhaustive. However, due to its clear advantage in speed, it can provide a\nlarge collection of galaxies that can be used for follow-up observations of\nobjects with ring morphology." }, { "anchor": "Physical Properties and Real Nature of Massive Clumps in the Galaxy: Systematic surveys of massive clumps have been carried out to study the\nconditions leading to the formation of massive stars. These clumps are\ntypically at large distances and unresolved, so their physical properties\ncannot be reliably derived from the observations alone. Numerical simulations\nare needed to interpret the observations. To this end, we generate synthetic\nHerschel observations using our large-scale star-formation simulation, where\nmassive stars explode as supernovae driving the interstellar-medium turbulence.\nFrom the synthetic observations, we compile a catalog of compact sources\nfollowing the exact same procedure as for the Hi-GAL compact source catalog. We\nshow that the sources from the simulation have observational properties with\nstatistical distributions consistent with the observations. By relating the\ncompact sources from the synthetic observations to their three-dimensional\ncounterparts in the simulation, we find that the synthetic observations\noverestimate the clump masses by about an order of magnitude on average due to\nline-of-sight projection, and projection effects are likely to be even worse\nfor Hi-GAL Inner Galaxy sources. We also find that a large fraction of sources\nclassified as protostellar are likely to be starless, and propose a new method\nto partially discriminate between true and false protostellar sources.", "positive": "Reconstructing the galaxy density field with photometric redshifts: I.\n Methodology and validation on stellar mass functions: Measuring environment for large numbers of distant galaxies is still an open\nproblem, for which we need galaxy positions and redshifts. Photometric\nredshifts are more easily available for large numbers of galaxies, but at the\nprice of larger uncertainties than spectroscopic ones. In this work we study\nhow photometric redshifts affect the measurement of galaxy environment and how\nthis may limit an analysis of the galaxy stellar mass function (GSMF) in\ndifferent environments. Using mock galaxy catalogues, we measured the\nenvironment with a fixed aperture method, using each galaxy's true and\nphotometric redshifts. We varied the fixed aperture volume parameters and the\nphotometric redshift uncertainties. We then computed GSMF as a function of\nredshift and environment. We found that only when using high-precision\nphotometric redshifts with $\\sigma_{\\Delta z/(1+z)} \\le 0.01$, the most extreme\nenvironments can be reconstructed in a fairly accurate way, with a fraction\n$\\ge 60\\div 80\\%$ of galaxies placed in the correct density quartile and a\ncontamination of $\\le 10\\%$ by opposite quartile interlopers. A volume height\ncomparable to the $\\pm 1.5\\sigma$ error of photometric redshifts grants a\nbetter reconstruction than other volume configurations. When using such an\nenvironmental measure, we found that any differences between the starting GSMF\n(divided accordingly to the true galaxy environment) will be damped on average\nof $\\sim 0.3$ dex when using photometric redshifts, but will be still\nresolvable. These results may be used to interpret real data as we obtained\nthem in a way that is fairly independent from how well the mock catalogues\nreproduce the real galaxy distribution. This work represents a preparatory\nstudy for future wide area photometric redshift surveys such as the Euclid\nSurvey and we plan to apply these results to an analysis of the GSMF in the\nUltraVISTA Survey in future work." }, { "anchor": "A Galactic O2 If*/WN6 star possibly ejected from its birthplace in\n NGC3603: In this work I report the discovery of a new Galactic O2 If*/WN6 star, a rare\nmember of the extremely massive hydrogen core-burning group of stars that due\nits high intrinsic luminosity (close to the Eddington limit), possess an\nemission-line spectrum at the beginning of their main-sequence evolution,\nmimicking the spectral appearance of classical WR stars. The new star is named\nWR42e and is found in isolation at 2.7 arcmin (about 6 pc) from the core of the\nstar-burst cluster NGC3603. From the computed E(B-V) color excess and observed\nvisual magnitude it was possible to estimate its absolute visual magnitude as\nMV =-6.3 mag, which is a value similar to those obtained by other researchers\nfor stars of similar spectral type both, in the Galaxy and in the Large\nMagellanic Cloud. Considering the derived absolute visual magnitude, we\ncomputed a bolometric stellar luminosity of about 3.2x106 Lsun. Finally, the\nmass of the new O2If*/WN6 star was estimated by comparing its observed\nmagnitudes and colors with those of other probable NGC3603 cluster members,\nfounding that the WR42e initial mass possibly exceeds 100 Msun.", "positive": "On the accuracy of HI observations in molecular clouds -- More cold HI\n than thought?: We present a study of the cold atomic hydrogen (HI) content of molecular\nclouds simulated within the SILCC-Zoom project. We produce synthetic\nobservations of HI at 21 cm including HI self-absorption (HISA) and\nobservational effects. We find that HI column densities, $N_\\textrm{HI}$, of\n$\\gtrsim$10$^{22}$ cm$^{-2}$ are frequently reached in molecular clouds with HI\ntemperatures as low as $\\sim$10 K. Hence, HISA observations assuming a fixed HI\ntemperature tend to underestimate the amount of cold HI in molecular clouds by\na factor of 3 - 10 and produce an artificial upper limit of $N_\\textrm{HI}$\naround 10$^{21}$ cm$^{-2}$. We thus argue that the cold HI mass in clouds could\nbe a factor of a few higher than previously estimated. Also\n$N_\\textrm{HI}$-PDFs obtained from HISA observations might be subject to\nobservational biases and should be considered with caution. The underestimation\nof cold HI in HISA observations is due to both the large HI temperature\nvariations and the effect of noise in regions of high optical depth. We find\noptical depths of cold HI around 1 - 10 making optical depth corrections\nessential. We show that the high HI column densities ($\\gtrsim$10$^{22}$\ncm$^{-2}$) can in parts be attributed to the occurrence of up to 10 individual\nHI-H$_2$ transitions along the line of sight. This is also reflected in the\nspectra, necessitating Gaussian decomposition algorithms for their analysis.\nHowever, also for a single HI-H$_2$ transition, $N_\\textrm{HI}$ frequently\nexceeds 10$^{21}$ cm$^{-2}$, challenging 1D, semi-analytical models. This is\ndue to non-equilibrium chemistry effects and the fact that HI-H$_2$ transition\nregions usually do not possess a 1-dimensional geometry. Finally, we show that\nthe HI gas is moderately supersonic with Mach numbers of a few. The\ncorresponding non-thermal velocity dispersion can be determined via HISA\nobservations within a factor of $\\sim$2." }, { "anchor": "Eddington's Demon: Inferring Galaxy Mass Functions and other\n Distributions from Uncertain Data: We present a general modified maximum likelihood (MML) method for inferring\ngenerative distribution functions from uncertain and biased data. The MML\nestimator is identical to, but easier and many orders of magnitude faster to\ncompute than the solution of the exact Bayesian hierarchical modelling of all\nmeasurement errors. As a key application, this method can accurately recover\nthe mass function (MF) of galaxies, while simultaneously dealing with\nobservational uncertainties (Eddington bias), complex selection functions and\nunknown cosmic large-scale structure. The MML method is free of binning and\nnatively accounts for small number statistics and non-detections. Its fast\nimplementation in the R-package \"dftools\" is equally applicable to other\nobjects, such as haloes, groups and clusters, as well as observables other than\nmass. The formalism readily extends to multi-dimensional distribution\nfunctions, e.g. a Choloniewski function for the galaxy mass-angular momentum\ndistribution, also handled by dftools. The code provides uncertainties and\ncovariances for the fitted model parameters and approximate Bayesian evidences.\nWe use numerous mock surveys to illustrate and test the MML method, as well as\nto emphasise the necessity of accounting for observational uncertainties in MFs\nof modern galaxy surveys.", "positive": "RR Lyrae Variables in M31 and M33: The properties of RR Lyrae variables make them excellent probes of the\nformation and evolution of a stellar population. The mere presence of such\nstars necessitates an age greater than ~10 Gyr while their periods and\namplitudes can be used to estimate the metal abundance of the cluster or galaxy\nin which they reside. These and other features of RR Lyraes have been used to\nstudy the properties of M31 and M33. Though these studies are generally in\ntheir infancy, we have established that M31 and M33 do indeed harbor RR Lyraes\nin their halos and probably also in their disks suggesting that these two\ncomponents formed early in the history of M31 and M33. The mean metallicities\nof the halo RR Lyraes in these galaxies are consistent with those of other halo\nstellar population tracers such as the dwarf spheroidal satellites of M31 and\nthe halo globular clusters in M33. Little is known about the spatial\ndistribution of the RR Lyraes, especially in M33. This will require wide-field\ntime-series studies with sufficient photometric depth to allow both the\nidentification of RR Lyraes and robust period determination." }, { "anchor": "Detection of the Milky Way spiral arms in dust from 3D mapping: Large stellar surveys are sensitive to interstellar dust through the effects\nof reddening. Using extinctions measured from photometry and spectroscopy,\ntogether with three-dimensional (3D) positions of individual stars, it is\npossible to construct a three-dimensional dust map. We present the first\ncontinuous map of the dust distribution in the Galactic disk out to 7 kpc\nwithin 100 pc of the Galactic midplane, using red clump and giant stars from\nSDSS APOGEE DR14. We use a non-parametric method based on Gaussian Processes to\nmap the dust density, which is the local property of the ISM rather than an\nintegrated quantity. This method models the dust correlation between points in\n3D space and can capture arbitrary variations, unconstrained by a pre-specified\nfunctional form. This produces a continuous map without line-of-sight\nartefacts. Our resulting map traces some features of the local Galactic spiral\narms, even though the model contains no prior suggestion of spiral arms, nor\nany underlying model for the Galactic structure. This is the first time that\nsuch evident arm structures have been captured by a dust density map in the\nMilky Way. Our resulting map also traces some of the known giant molecular\nclouds in the Galaxy and puts some constraints on their distances, some of\nwhich were hitherto relatively uncertain.", "positive": "The redshift distribution of submillimetre galaxies at different\n wavelengths: Using simulations we demonstrate that some of the published redshift\ndistributions of submillimetre galaxies (SMGs) at different wavelengths, which\nwere previously reported to be statistically different, are consistent with a\nparent distribution of the same population of galaxies. The redshift\ndistributions which peak at z_med=2.9, 2.6, 2.2, 2.2, and 2.0 for galaxies\nselected at 2 and 1.1 mm, and 870, 850, and 450 um respectively, can be derived\nfrom a single parent redshift distribution, in contrast with previous studies.\nThe differences can be explained through wavelength selection, depth of the\nsurveys, and to a lesser degree, angular resolution. The main differences are\nattributed to the temperature of the spectral energy distributions, as\nshorter-wavelength maps select a hotter population of galaxies. Using the same\nparent distribution and taking into account lensing bias we can also reproduce\nthe redshift distribution of 1.4 mm-selected ultra-bright galaxies, which peaks\nat z_med=3.4. However, the redshift distribution of 450 um-selected galaxies in\nthe deepest surveys, which peaks at z_med=1.4, cannot be reproduced from the\nsame parent population with just these selection effects. In order to explain\nthis distribution we have to add another population of galaxies or include\ndifferent selection biases." }, { "anchor": "The Milky Way's circular velocity curve and its constraint on the\n Galactic mass with RR Lyrae stars: We present a sample of 1148 ab-type RR Lyrae (RRLab) variables identified\nfrom Catalina Surveys Data Release 1, combined with SDSS DR8 and LAMOST DR4\nspectral data. We firstly use a large sample of 860 Galactic halo RRLab stars\nand derive the circular velocity distributions for the stellar halo. With the\nprecise distances and carefully determined radial velocities (the\ncenter-of-mass radial velocities) by considering the pulsation of the RRLab\nstars in our sample, we can obtain a reliable and comparable stellar halo\ncircular velocity curve. We take two different prescriptions for the velocity\nanisotropy parameter {\\beta} in the Jeans equation to study the circular\nvelocity curve and mass profile. We test two different solar peculiar motions\nin our calculation. Our best result with the adopted solar peculiar motion 1 of\n(U, V, W) = (11.1, 12, 7.2) km/s is that the enclosed mass of the Milky Way\nwithin 50 kpc is (3.75 +/- 1.33) *10^11Msun based on \\beta = 0 and the circular\nvelocity 180 +/- 31.92 (km/s) at 50 kpc. This result is consistent with\ndynamical model results, and it is also comparable to the previous similar\nworks.", "positive": "The Star Formation Rate of Molecular Clouds: We review recent advances in the analytical and numerical modeling of the\nstar formation rate in molecular clouds and discuss the available observational\nconstraints. We focus on molecular clouds as the fundamental star formation\nsites, rather than on the larger-scale processes that form the clouds and set\ntheir properties. Molecular clouds are shaped into a complex filamentary\nstructure by supersonic turbulence, with only a small fraction of the cloud\nmass channeled into collapsing protostars over a free-fall time of the system.\nIn recent years, the physics of supersonic turbulence has been widely explored\nwith computer simulations, leading to statistical models of this fragmentation\nprocess, and to the prediction of the star formation rate as a function of\nfundamental physical parameters of molecular clouds, such as the virial\nparameter, the rms Mach number, the compressive fraction of the turbulence\ndriver, and the ratio of gas to magnetic pressure. Infrared space telescopes,\nas well as ground-based observatories have provided unprecedented probes of the\nfilamentary structure of molecular clouds and the location of forming stars\nwithin them." }, { "anchor": "Formation of S0s in extreme environments I: clues from kinematics and\n stellar populations: Despite numerous efforts, it is still unclear whether lenticular galaxies\n(S0s) evolve from spirals whose star formation was suppressed, or formed trough\nmergers or disk instabilities. In this paper we present a pilot study of 21 S0\ngalaxies in extreme environments (field and cluster), and compare their\nspatially-resolved kinematics and global stellar populations. Our aim is to\nidentify whether there are different mechanisms that form S0s in different\nenvironments. Our results show that the kinematics of S0 galaxies in field and\ncluster are, indeed, different. Lenticulars in the cluster are more\nrotationally supported, suggesting that they are formed through processes that\ninvolve the rapid consumption or removal of gas (e.g. starvation, ram pressure\nstripping). In contrast, S0s in the field are more pressure supported,\nsuggesting that minor mergers served mostly to shape their kinematic\nproperties. These results are independent of total mass, luminosity, or\ndisk-to-bulge ratio. On the other hand, the mass-weighted age, metallicity, and\nstar formation time-scale of the galaxies correlate more with mass than with\nenvironment, in agreement with known relations from previous work such as the\none between mass and metallicity. Overall, our results re-enforce the idea that\nthere are multiple mechanisms that produce S0s, and that both mass $and$\nenvironment play key roles. A larger sample is highly desirable to confirm or\nrefute the results and the interpretation of this pilot study.", "positive": "Planck Early Results: The submillimetre properties of a sample of\n Galactic cold clumps: (abridged) We perform a detailed investigation of sources from the Cold Cores\nCatalogue of Planck Objects (C3PO). Our goal is to probe the reliability of the\ndetections, validate the separation between warm and cold dust emission\ncomponents, provide the first glimpse at the nature, internal morphology and\nphysical characterictics of the Planck-detected sources. We focus on a\nsub-sample of ten sources from the C3PO list, selected to sample different\nenvironments, from high latitude cirrus to nearby (150pc) and remote (2kpc)\nmolecular complexes. We present Planck surface brightness maps and derive the\ndust temperature, emissivity spectral index, and column densities of the\nfields. With the help of higher resolution Herschel and AKARI continuum\nobservations and molecular line data, we investigate the morphology of the\nsources and the properties of the substructures at scales below the Planck beam\nsize." }, { "anchor": "A proper motion study of the globular cluster M55: We have derived the absolute proper motion (PM) of the globular cluster M55\nusing a large set of CCD images collected with the du Pont telescope between\n1997 and 2008. We find (PM_RA*cos(DEC), PM_DEC) = (-3.31 +/- 0.10, -9.14 +/-\n0.15) mas/yr relative to background galaxies. Membership status was determined\nfor 16 945 stars with 1430$ kpc, respectively. Metal-poor stars with [Fe/H]$<-2$ are a\nsmall population of the halo at all distances and orbital categories. We\nassociate the \"in-situ\" stellar halo with stars displaying thick-disk chemistry\non halo-like orbits; such stars are confined to $|z|<10$ kpc. The majority of\nthe stellar halo is resolved into discrete features in orbital-chemical space,\nsuggesting that the bulk of the stellar halo formed from the accretion and\ntidal disruption of dwarf galaxies. (ABRIDGED)", "positive": "SDSS J1254+0846: A Binary Quasar Caught in the Act of Merging: We present the first luminous, spatially resolved binary quasar that clearly\ninhabits an ongoing galaxy merger. SDSS J125455.09+084653.9 and SDSS\nJ125454.87+084652.1 (SDSS J1254+0846 hereafter) are two luminous z=0.44 radio\nquiet quasars, with a radial velocity difference of just 215 km/s, separated on\nthe sky by 21 kpc in a disturbed host galaxy merger showing obvious tidal\ntails. The pair was targeted as part of a complete sample of binary quasar\ncandidates with small transverse separations drawn from SDSS DR6 photometry. We\npresent follow-up optical imaging which shows broad, symmetrical tidal arm\nfeatures spanning some 75 kpc at the quasars' redshift. Numerical modeling\nsuggests that the system consists of two massive disk galaxies prograde to\ntheir mutual orbit, caught during the first passage of an active merger. This\ndemonstrates rapid black hole growth during the early stages of a merger\nbetween galaxies with pre-existing bulges. Neither of the two luminous nuclei\nshow significant instrinsic absorption by gas or dust in our optical or X-ray\nobservations, illustrating that not all merging quasars will be in an obscured,\nultraluminous phase. We find that the Eddington ratio for the fainter component\nB is rather normal, while for the A component L/LEdd is quite (>3sigma) high\ncompared to quasars of similar luminosity and redshift, possibly evidence for\nstrong merger-triggered accretion. More such mergers should be identifiable at\nhigher redshifts using binary quasars as tracers." }, { "anchor": "Discovery of diffuse optical emission lines from the inner Galaxy:\n Evidence for LI(N)ER-like gas: Optical emission lines are used to categorize galaxies into three groups\naccording to their dominant central radiation source: active galactic nuclei,\nstar formation, or low-ionization (nuclear) emission regions [LI(N)ERs] that\nmay trace ionizing radiation from older stellar populations. Using the\nWisconsin H-Alpha Mapper, we detect optical line emission in low-extinction\nwindows within eight degrees of Galactic Center. The emission is associated\nwith the 1.5-kiloparsec-radius \"Tilted Disk\" of neutral gas. We modify a model\nof this disk and find that the hydrogen gas observed is at least $48\\%$\nionized. The ratio [NII] $\\lambda$6584\n$\\overset{\\lower.5em\\circ}{\\mathrm{A}}$/H$\\alpha$ $\\lambda$6563\n$\\overset{\\lower.5em\\circ}{\\mathrm{A}}$ increases from 0.3 to 2.5 with\nGalactocentric radius; [OIII] $\\lambda$5007\n$\\overset{\\lower.5em\\circ}{\\mathrm{A}}$ and H$\\beta$ $\\lambda$4861\n$\\overset{\\lower.5em\\circ}{\\mathrm{A}}$ are also sometimes detected. The line\nratios for most Tilted Disk sightlines are characteristic of LI(N)ER galaxies.", "positive": "Ultra-bright CO and [CI] emission in a lensed z=2.04 submillimeter\n galaxy with extreme molecular gas properties: We report the very bright detection of cold molecular gas with the IRAM NOEMA\ninterferometer of the strongly lensed source WISE J132934.18+224327.3 at\nz=2.04, the so-called Cosmic Eyebrow. This source has a similar spectral energy\ndistribution from optical-mid/IR to submm/radio but significantly higher fluxes\nthan the well-known lensed SMG SMMJ 2135, the Cosmic Eyelash at z=2.3. The\ninterferometric observations identify unambiguously the location of the\nmolecular line emission in two components, component CO32-A with\nI_CO(3-2)=52.2+-0.9 Jy km s^-1 and component CO32-B with I_CO(3-2)=15.7+-0.7 Jy\nkm s^-1. Thus, our NOEMA observations of the CO(3-2) transition confirm the\nSMG-nature of WISE J132934.18+224327.3, resulting in the brightest CO(3-2)\ndetection ever of a SMG. In addition, we present follow-up observations of the\nbrighter component with the Green Bank Telescope (CO(1-0) transition) and IRAM\n30m telescope (CO(4-3) and [CI](1-0) transitions). The star-formation\nefficiency of ~100 L_sun (K km s^-1 pc^2) is at the overlap region between\nmerger-triggered and disk-like star-formation activity and the lowest seen for\nlensed dusty star-forming galaxies. The determined gas depletion time ~60~Myr,\nintrinsic infrared star-formation SFR_IR approx. 2000 M_sun yr^-1 and gas\nfraction M_mol/M_star=0.44 indicates a starburst/merger triggered\nstar-formation. The obtained data of the cold ISM - from CO(1-0) and dust\ncontinuum - indicates a gas mass M_mol~15x10^11 M_sun for component CO32-A. Its\nunseen brightness offers the opportunity to establish the Cosmic Eyebrow as a\nnew reference source at z=2 for galaxy evolution." }, { "anchor": "Metallicity evolution of direct collapse black hole hosts: CR7 as a case\n study: In this study we focus on the $z\\sim6.6$ Lyman-$\\alpha$ CR7 consisting of\nclump A that is host to a potential direct collapse black hole (DCBH), and two\nmetal enriched star forming clumps B and C. In contrast to claims that\nsignatures of metals rule out the existence of DCBHs, we show that metal\npollution of A from star forming clumps clumps B and C is inevitable, and that\nA can form a DCBH well before its metallicity exceeds the critical threshold of\n$10^{-5}-10^{-6}\\ \\rm Z_{\\odot}$. Assuming metal mixing happens\ninstantaneously, we derive the metallicity of A based on the star formation\nhistory of B and C. We find that treating a final accreting black hole of\n$10^6-10^7\\ \\rm M_{\\odot}$ in A for nebular emission already pushes its\n$H_{160}$ - [3.6] and [3.6]-[4.5] colours into the 3$\\sigma$ limit of\nobservations. Hence, we show that the presence of metals in DCBH hosts is\ninevitable, and that it is the coevolution of the LW radiation field and metals\noriginating from neighbouring galaxies that governs DCBH formation in a\nneighbouring {initially} pristine atomic cooling haloes.", "positive": "Extended Line Emission in the BCG of Abell 2390: We report CFHT/SITELLE imaging Fourier Transform Spectrograph observations of\nthe Brightest Cluster Galaxy (BCG) of galaxy cluster Abell 2390 at z=0.228. The\nBCG displays a prominent cone of emission in H$\\alpha$, H$\\beta$, [NII], and\n[OII] to the North-West with PA = 42$^o$, 4.4 arcsec in length (15.9 kpc),\nwhich is associated with elongated and asymmetric Chandra soft X-ray emission.\nThe H$\\alpha$ flux map also contains a \"hook\" of H$\\alpha$ and [NII] emission\nresulting in a broadened northern edge to the cone. Using SITELLE/LUCI software\nwe extract emission line flux, velocity, velocity dispersion, and continuum\nmaps, and utilize them to derive flux ratio maps to determine ionization\nmechanisms and dynamical information in the BCG's emission line region. The\nBaldwin-Phillips-Terlevich diagnostics on the BCG cone indicate a composite\nionization origin of photoionization due to star formation and shock. Strong\nLINER-like emission is seen in the nuclear region which hosts an AGN. As Abell\n2390 is a cool-core cluster, we suggest that the cooling flow is falling onto\nthe central BCG and interacting with the central AGN. The AGN produces jets\nthat inflate \"bubbles\" of plasma in the ICM, as is often observed in local\ngalaxy clusters. Furthermore, combining signs of AGN activities from radio,\noptical emission line and X-ray data over a large range of physical scale, we\nfind evidence for three possible episodes of AGN activity in different epochs\nassociated with the Abell 2390 BCG." }, { "anchor": "GASS: The Parkes Galactic All-Sky Survey. I. Survey Description, Goals,\n and Initial Data Release: The Parkes Galactic All-Sky Survey (GASS) is a survey of Galactic atomic\nhydrogen (HI) emission in the Southern sky covering declinations $\\delta \\leq\n1^{\\circ}$ using the Parkes Radio Telescope. The survey covers $2\\pi$\nsteradians with an effective angular resolution of ~16', at a velocity\nresolution of 1.0 km/s, and with an rms brightness temperature noise of 57 mK.\nGASS is the most sensitive, highest angular resolution survey of Galactic HI\nemission ever made in the Southern sky. In this paper we outline the survey\ngoals, describe the observations and data analysis, and present the first-stage\ndata release. The data product is a single cube at full resolution, not\ncorrected for stray radiation. Spectra from the survey and other data products\nare publicly available online.", "positive": "Detection of interstellar HCS and its metastable isomer HSC: new pieces\n in the puzzle of sulfur chemistry: We present the first identification in interstellar space of the thioformyl\nradical (HCS) and its metastable isomer HSC. These species were detected toward\nthe molecular cloud L483 thanks to observations carried out with the IRAM 30m\ntelescope in the 3 mm band. We derive beam-averaged column densities of 7e12\ncm-2 for HCS and 1.8e11 cm-2 for HSC, which translate to fractional abundances\nrelative to H2 of 2e-10 and 6e-12, respectively. Although the amount of sulfur\nlocked by these radicals is low, their detection allows to put interesting\nconstraints on the chemistry of sulfur in dark clouds. Interestingly, the\nH2CS/HCS abundance ratio is found to be quite low, around 1, in contrast with\nthe oxygen analogue case, in which the H2CO/HCO abundance ratio is around 10 in\ndark clouds. Moreover, the radical HCS is found to be more abundant than its\noxygen analogue, HCO. The metastable species HOC, the oxygen analogue of HSC,\nhas not been yet observed in space. These observational constraints are\nconfronted with the outcome of a recent model of the chemistry of sulfur in\ndark clouds. The model underestimates the fractional abundance of HCS by at\nleast one order of magnitude, overestimates the H2CS/HCS abundance ratio, and\ndoes not provide an abundance prediction for the metastable isomer HSC. These\nobservations should prompt a revision of the chemistry of sulfur in\ninterstellar clouds." }, { "anchor": "Spitzer Observations of the North Ecliptic Pole: We present a photometric catalog for Spitzer Space Telescope warm mission\nobservations of the North Ecliptic Pole (NEP; centered at $\\rm\nR.A.=18^h00^m00^s$, $\\rm Decl.=66^d33^m38^s.552$). The observations are\nconducted with IRAC in 3.6 $\\mu$m and 4.5 $\\mu$m bands over an area of 7.04\ndeg$^2$ reaching 1$\\sigma$ depths of 1.29 $\\mu$Jy and 0.79 $\\mu$Jy in the 3.6\n$\\mu$m and 4.5 $\\mu$m bands respectively. The photometric catalog contains\n380,858 sources with 3.6 $\\mu$m and 4.5 $\\mu$m band photometry over the\nfull-depth NEP mosaic. Point source completeness simulations show that the\ncatalog is 80% complete down to 19.7 AB. The accompanying catalog can be\nutilized in constraining the physical properties of extra-galactic objects,\nstudying the AGN population, measuring the infrared colors of stellar objects,\nand studying the extra-galactic infrared background light.", "positive": "Dark matter halo cores and the tidal survival of Milky Way satellites: The cuspy central density profiles of cold dark matter (CDM) haloes make them\nhighly resilient to disruption by tides. Self-interactions between dark matter\nparticles, or the cycling of baryons, may result in the formation of a\nconstant-density core which would make haloes more susceptible to tidal\ndisruption. We use N-body simulations to study the evolution of NFW-like\n\"cored\" subhaloes in the tidal field of a massive host, and identify the\ncriteria and timescales for full tidal disruption. Our results imply that the\nsurvival of Milky Way satellites places constraints on the sizes of dark matter\ncores. Indeed, we find that no subhaloes with cores larger than 1 per cent of\ntheir initial NFW scale radius can survive for a Hubble time on orbits with\npericentres <10 kpc. A satellite like Tucana 3, with pericentre ~3.5 kpc, must\nhave a core size smaller than ~2 pc to survive just three orbital periods on\nits current orbit. The core sizes expected in self-interacting dark matter\n(SIDM) models with a velocity-independent cross section of 1 cm^2/g seem\nincompatible with ultra-faint satellites with small pericentric radii, such as\nTuc 3, Seg 1, Seg 2, Ret 2, Tri 2, and Wil 1, as these should have fully\ndisrupted if accreted on to the Milky Way >10 Gyr ago. These results suggest\nthat many satellites have vanishingly small core sizes, consistent with CDM\ncusps. The discovery of further Milky Way satellites on orbits with small\npericentric radii would strengthen these conclusions and allow for stricter\nupper limits on the core sizes." }, { "anchor": "The effect of the environment on the structure, morphology and\n star-formation history of intermediate-redshift galaxies: With the aim of understanding the effect of the environment on the star\nformation history and morphological transformation of galaxies, we present a\ndetailed analysis of the colour, morphology and internal structure of cluster\nand field galaxies at $0.4 \\le z \\le 0.8$. We use {\\em HST} data for over 500\ngalaxies from the ESO Distant Cluster Survey (EDisCS) to quantify how the\ngalaxies' light distribution deviate from symmetric smooth profiles. We\nvisually inspect the galaxies' images to identify the likely causes for such\ndeviations. We find that the residual flux fraction ($RFF$), which measures the\nfractional contribution to the galaxy light of the residuals left after\nsubtracting a symmetric and smooth model, is very sensitive to the degree of\nstructural disturbance but not the causes of such disturbance. On the other\nhand, the asymmetry of these residuals ($A_{\\rm res}$) is more sensitive to the\ncauses of the disturbance, with merging galaxies having the highest values of\n$A_{\\rm res}$. Using these quantitative parameters we find that, at a fixed\nmorphology, cluster and field galaxies show statistically similar degrees of\ndisturbance. However, there is a higher fraction of symmetric and passive\nspirals in the cluster than in the field. These galaxies have smoother light\ndistributions than their star-forming counterparts. We also find that while\nalmost all field and cluster S0s appear undisturbed, there is a relatively\nsmall population of star-forming S0s in clusters but not in the field. These\nfindings are consistent with relatively gentle environmental processes acting\non galaxies infalling onto clusters.", "positive": "The dragonfly nearby galaxies survey. Iv. A giant stellar disk in ngc\n 2841: Neutral gas is commonly believed to dominate over stars in the outskirts of\ngalaxies, and investigations of the disk-halo interface are generally\nconsidered to be in the domain of radio astronomy. This may simply be a\nconsequence of the fact that deep HI observations typically probe to a lower\nmass surface density than visible wavelength data. This paper presents low\nsurface brightness optimized visible wavelength observations of the extreme\noutskirts of the nearby spiral galaxy NGC 2841. We report the discovery of an\nenormous low-surface brightness stellar disk in this object. When azimuthally\naveraged, the stellar disk can be traced out to a radius of $\\sim$70 kpc (5\n$R_{25}$ or 23 inner disk scale lengths). The structure in the stellar disk\ntraces the morphology of HI emission and extended UV emission. Contrary to\nexpectations, the stellar mass surface density does not fall below that of the\ngas mass surface density at any radius. In fact, at all radii greater than\n$\\sim$20 kpc, the ratio of the stellar to gas mass surface density is a\nconstant 3:1. Beyond $\\sim$30 kpc, the low surface brightness stellar disk\nbegins to warp, which may be an indication of a physical connection between the\noutskirts of the galaxy and infall from the circumgalactic medium. A\ncombination of stellar migration, accretion and in-situ star formation might be\nresponsible for building up the outer stellar disk, but whatever mechanisms\nformed the outer disk must also explain the constant ratio between stellar and\ngas mass in the outskirts of this galaxy." }, { "anchor": "Too Many, Too Few, or Just Right? The Predicted Number and Distribution\n of Milky Way Dwarf Galaxies: We predict the spatial distribution and number of Milky Way dwarf galaxies to\nbe discovered in the DES and LSST surveys, by completeness correcting the\nobserved SDSS dwarf population. We apply most massive in the past, earliest\nforming, and earliest infall toy models to a set of dark matter-only simulated\nMilky Way/M31 halo pairs from Exploring the Local Volume In Simulations\n(ELVIS). The observed spatial distribution of Milky Way dwarfs in the LSST-era\nwill discriminate between the earliest infall and other simplified models for\nhow dwarf galaxies populate dark matter subhalos. Inclusive of all toy models\nand simulations, at 90% confidence we predict a total of 37-114 L $\\gtrsim\n10^3$L$_{\\odot}$ dwarfs and 131-782 L $\\lesssim 10^3$L$_{\\odot}$ dwarfs within\n300 kpc. These numbers of L $\\gtrsim 10^3$L$_{\\odot}$ dwarfs are dramatically\nlower than previous predictions, owing primarily to our use of updated\ndetection limits and the decreasing number of SDSS dwarfs discovered per sky\narea. For an effective $r_{\\rm limit}$ of 25.8 mag, we predict: 3-13 L $\\gtrsim\n10^3$L$_{\\odot}$ and 9-99 L $\\lesssim 10^3$L$_{\\odot}$ dwarfs for DES, and\n18-53 L $\\gtrsim 10^3$L$_{\\odot}$ and 53-307 L $\\lesssim 10^3$L$_{\\odot}$\ndwarfs for LSST. These enormous predicted ranges ensure a coming decade of\nnear-field excitement with these next generation surveys.", "positive": "Reverberation Mapping of Two Luminous Quasars: the Broad-line Region\n Structure and Black Hole Mass: We report the results of a multi-year spectroscopic and photometric\nmonitoring campaign of two luminous quasars, PG~0923+201 and PG~1001+291, both\nlocated at the high-luminosity end of the broad-line region (BLR)\nsize-luminosity relation with optical luminosities above $10^{45}~{\\rm\nerg~s^{-1}}$. PG~0923+201 is for the first time monitored, and PG~1001+291 was\npreviously monitored but our campaign has a much longer temporal baseline. We\ndetect time lags of variations of the broad H$\\beta$, H$\\gamma$, Fe {\\sc ii}\nlines with respect to those of the 5100~{\\AA} continuum. The velocity-resolved\ndelay map of H$\\beta$ in PG~0923+201 indicates a complicated structure with a\nmix of Keplerian disk-like motion and outflow, and the map of H$\\beta$ in\nPG~1001+291 shows a signature of Keplerian disk-like motion. Assuming a virial\nfactor of $f_{\\rm BLR}=1$ and FWHM line widths, we measure the black hole mass\nto be $118_{-16}^{+11}\\times 10^7 M_{\\odot}$ for PG~0923+201 and\n$3.33_{-0.54}^{+0.62}\\times 10^7 M_{\\odot}$ for PG~1001+291. Their respective\naccretion rates are estimated to be $0.21_{-0.07}^{+0.06} \\times L_{\\rm\nEdd}\\,c^{-2}$ and $679_{-227}^{+259}\\times L_{\\rm Edd}\\,c^{-2}$, indicating\nthat PG~0923+201 is a sub-Eddington accretor and PG~1001+291 is a\nsuper-Eddington accretor. While the H$\\beta$ time lag of PG~0923+201 agrees\nwith the size-luminosity relation, the time lag of PG~1001+291 shows a\nsignificant deviation, confirming that in high-luminosity AGN the BLR size\ndepends on both luminosity and Eddington ratio. Black hole mass estimates from\nsingle AGN spectra will be over-estimated at high luminosities and redshifts if\nthis effect is not taken into account." }, { "anchor": "Thermodynamics sheds light on the nature of dark matter galactic halos: Today it is understood that our universe would not be the same without dark\nmatter, which apparently has given rise to the formation of galaxies, stars and\nplanets. Its existence is inferred mainly from the gravitational effect on the\nrotation curves of stars in spiral galaxies. The nature of dark matter remains\nunknown. Here we show that the dark matter halo is in a state of Bose-Einstein\ncondensation, or at least the central region is. By using fittings of\nobservational data, we can put an upper bound on the dark matter particle mass\nin the order of $12~\\,eV/c^2$. We present the temperature profiles of galactic\ndark matter halos by considering that dark matter can be treated as a classical\nideal gas, as an ideal Fermi gas, or as an ideal Bose gas. The only free\nparameter in the matter model is the mass of the dark matter particle. We\nobtain the temperature profiles by using the rotational velocity profile\nproposed by Persic, Salucci, and Stel (1996) and assuming that the dark matter\nhalo is a self-gravitating stand-alone structure. From the temperature\nprofiles, we conclude that the classical ideal gas and the ideal Fermi gas are\nnot viable explanations for dark matter, while the ideal Bose gas is if the\nmass of the particle is low enough. If we take into account the relationship\npresented by Kormendy and Freeman (2004, 2016), Donato et al. (2009) and\nGentile et al. (2009) between central density and core radius then we conclude\nthat the central temperature of dark matter in all galaxies is the same.\nRemarkably, our results imply that basics thermodynamics principles could shed\nlight on the mysterious nature of dark matter and if this is the case, those\nprinciples have to been taken into account in its description.", "positive": "Radial orbit instability in systems of highly eccentric orbits: Antonov\n problem reviewed: Stationary stellar systems with radially elongated orbits are subject to\nradial orbit instability -- an important phenomenon that structures galaxies.\nAntonov (1973) presented a formal proof of the instability for spherical\nsystems in the limit of purely radial orbits. However, such spheres have highly\ninhomogeneous density distributions with singularity $\\sim 1/r^2$, resulting in\nan inconsistency in the proof. The proof can be refined, if one considers an\norbital distribution close to purely radial, but not entirely radial, which\nallows to avoid the central singularity. For this purpose we employ\nnon-singular analogs of generalised polytropes elaborated recently in our work\nin order to derive and solve new integral equations adopted for calculation of\nunstable eigenmodes in systems with nearly radial orbits. In addition, we\nestablish a link between our and Antonov's approaches and uncover the meaning\nof infinite entities in the purely radial case. Maximum growth rates tend to\ninfinity as the system becomes more and more radially anisotropic. The\ninstability takes place both for even and odd spherical harmonics, with all\nunstable modes developing rapidly, i.e. having eigenfrequencies comparable to\nor greater than typical orbital frequencies. This invalidates orbital\napproximation in the case of systems with all orbits very close to purely\nradial." }, { "anchor": "Linking galaxies to dark matter haloes at $z\\sim1$ : dependence of\n galaxy clustering on stellar mass and specific star formation rate: We study the dependence of angular two-point correlation functions on stellar\nmass ($M_{*}$) and specific star formation rate (sSFR) of\n$M_{*}>10^{10}M_{\\odot}$ galaxies at $z\\sim1$. The data from UKIDSS DXS and\nCFHTLS covering 8.2 deg$^{2}$ sample scales larger than 100 $h^{-1}$Mpc at\n$z\\sim1$, allowing us to investigate the correlation between clustering,\n$M_{*}$, and star formation through halo modeling. Based on halo occupation\ndistributions (HODs) of $M_{*}$ threshold samples, we derive HODs for $M_{*}$\nbinned galaxies, and then calculate the $M_{*}/M_{\\rm halo}$ ratio. The ratio\nfor central galaxies shows a peak at $M_{\\rm halo}\\sim10^{12}h^{-1}M_{\\odot}$,\nand satellites predominantly contribute to the total stellar mass in cluster\nenvironments with $M_{*}/M_{\\rm halo}$ values of 0.01--0.02. Using star-forming\ngalaxies split by sSFR, we find that main sequence galaxies ($\\rm\nlog\\,sSFR/yr^{-1}\\sim-9$) are mainly central galaxies in $\\sim10^{12.5}\nh^{-1}M_{\\odot}$ haloes with the lowest clustering amplitude, while lower sSFR\ngalaxies consist of a mixture of both central and satellite galaxies where\nthose with the lowest $M_{*}$ are predominantly satellites influenced by their\nenvironment. Considering the lowest $M_{\\rm halo}$ samples in each $M_{*}$ bin,\nmassive central galaxies reside in more massive haloes with lower sSFRs than\nlow mass ones, indicating star-forming central galaxies evolve from a low\n$M_{*}$--high sSFR to a high $M_{*}$--low sSFR regime. We also find that the\nmost rapidly star-forming galaxies ($\\rm log\\,sSFR/yr^{-1}>-8.5$) are in more\nmassive haloes than main sequence ones, possibly implying galaxy mergers in\ndense environments are driving the active star formation. These results support\nthe conclusion that the majority of star-forming galaxies follow secular\nevolution through the sustained but decreasing formation of stars.", "positive": "OB Stars in Stochastic Regimes: The highest-mass stars have the lowest frequency in the stellar IMF, and they\nare also the most easily observed stars. Thus, the counting statistics for OB\nstars provide important tests for the fundamental nature and quantitative\nparameters of the IMF. We first examine some local statistics for the stellar\nupper-mass limit itself. Then, we examine the parameter space and statistics\nfor extremely sparse clusters that contain OB stars, in the SMC. We find that\nthus far, these locally observed counting statistics are consistent with a\nconstant stellar upper-mass limit. The sparse OB star clusters easily fall\nwithin the parameter space of Monte Carlo simulations of cluster populations.\nIf the observed objects are representative of their cluster birth masses, their\nexistence implies that the maximum stellar mass is largely independent of the\nparent cluster mass." }, { "anchor": "Statistical analysis of the interplay between magnetic fields and\n filaments hosting Planck Galactic Cold Clumps: We present a statistical study of the relative orientation in the plane of\nthe sky between interstellar magnetic fields and filaments hosting cold clumps.\nFor the first time, we consider both the density of the environment and the\ndensity contrast between the filaments and their environment. Moreover, we\ngeometrically distinguish between the clumps and the remaining portions of the\nfilaments. We infer the magnetic field orientations in the filaments and in\ntheir environment from the Stokes parameters, assuming optically thin\nconditions. Thus, we analyze the relative orientations between filaments,\nembedded clumps, and internal and background magnetic fields, depending on the\nfilament environment and evolutionary stages. We recover the previously\nobserved trend for filaments in low column density environments to be aligned\nparallel to the background magnetic field; however, we find that this trend is\nsignificant only for low contrast filaments, whereas high contrast filaments\ntend to be randomly orientated with respect to the background magnetic field.\nFilaments in high column density environments do not globally show any\npreferential orientation, although low contrast filaments alone tend to have\nperpendicular relative orientation with respect to the background magnetic\nfield. For a subsample of nearby filaments, for which volume densities can be\nderived, we find a clear transition in the relative orientation with increasing\ndensity, at $n_{\\rm H} \\sim 10^{3}~{\\rm cm}^{-3}$, changing from mostly\nparallel to mostly perpendicular in the off-clump portions of filaments and\nfrom even to bimodal in the clumps. Our results confirm a strong interplay\nbetween interstellar magnetic fields and filaments during their formation and\nevolution.", "positive": "The abundance of compact quiescent galaxies since z ~ 0.6: We set out to quantify the number density of quiescent massive compact\ngalaxies at intermediate redshifts. We determine structural parameters based on\ni-band imaging using the CFHT equatorial SDSS Stripe 82 (CS82) survey (~170 sq.\ndegrees) taking advantage of an exquisite median seeing of ~0.6''. We select\ncompact massive (M > 5x10^10 M_sun) galaxies within the redshift range of\n0.210. We systematically measure a factor of ~5 more\ncompacts at the same redshift than what was previously reported on smaller\nfields with HST imaging, which are more affected by cosmic variance. This means\nthat the decrease in number density from z ~ 1.5 to z ~ 0.2 might be only of a\nfactor of ~2-5, significantly smaller than what previously reported. This\nsupports progenitor bias as the main contributor to the size evolution. This\nmilder decrease is roughly compatible with the predictions from recent\nnumerical simulations. Only the most extreme compact galaxies, with Reff <\n1.5x( M/10^11 M_sun)^0.75 and M > 10^10.7 M_sun, appear to drop in number by a\nfactor of ~20 and hence likely experience a noticeable size evolution." }, { "anchor": "The local Tully-Fisher relation for dwarf galaxies: We study different incarnations of the Tully-Fisher (TF) relation for the\nLocal Volume (LV) galaxies taken from Updated Nearby Galaxy Catalog. The UNGC\nsample contains 656 galaxies with $W_{50}$ HI-line-width estimates, mostly\nbelonging to low mass dwarfs. Of them, 296 objects have distances measured with\naccuracy better than 10%. For the sample of 331 LV galaxies having baryonic\nmasses $\\log M_{bar} > 5.8 \\log M_\\odot$ we obtain a relation $\\log M_{bar}=\n2.49 \\log W_{50} + 3.97$ with observed scatter of 0.38 dex. The largest factors\naffecting the scatter are observational errors in $K$-band magnitudes and\n$W_{50}$ line widths for the tiny dwarfs, as well as uncertainty of their\ninclinations. We find that accounting for the surface brightness of the LV\ngalaxies, or their gas fraction, or specific star formation rate, or the\nisolation index do not reduce essentially the observed scatter on the baryonic\nTF-diagram. We also notice that a sample of 71 dSph satellites of the Milky Way\nand M31 with known stellar velocity dispersion $\\sigma^*$ tends to follow\nnearly the same bTF relation, having slightly lower masses than that of\nlate-type dwarfs.", "positive": "Very Compact Dense Galaxy Overdensity with \u03b4 ~ 130 Identified at\n z ~ 8: Implications for Early Protocluster and Cluster-Core Formation: We report the first identification of a compact dense galaxy overdensity at\n$z\\sim8$ dubbed A2744z8OD. A2744z8OD consists of eight $Y$-dropout galaxies\nbehind Abell 2744 that is originally pinpointed by Hubble Frontier Fields\nstudies. However, no studies have, so far, derived basic physical quantities of\nstructure formation or made comparisons with theoretical models. We obtain a\nhomogeneous sample of dropout galaxies at $z\\sim8$ from eight field data of\nHubble legacy images that are as deep as the A2744z8OD data. Using the sample,\nwe find that a galaxy surface overdensity value of A2744z8OD is very high\n$\\delta\\simeq130$, where $\\delta$ is defined by an overdensity in a small\ncircle of $6\"$ ($\\simeq30$ physical kpc) radius. Because there is no such a\nlarge $\\delta$ value reported for high-$z$ overdensities to date, A2744z8OD is\na system clearly different from those found in previous high-$z$ overdensity\nstudies. In the galaxy+structure formation models of Henriques et al. (2015),\nthere exist a very similar overdensity, Modelz8OD, that is made of eight model\ndropout galaxies at $z\\sim8$ in a $6\"$-radius circle. Modelz8OD is a progenitor\nof a today's $10^{14}M_\\odot$ cluster, and more than a half of the seven\nModelz8OD galaxies are merged into the brightest cluster galaxy (BCG) of the\ncluster. If Modelz8OD is a counterpart of A2744z8OD, the models suggest that\nA2744z8OD would be a part of a forming cluster core of a today's\n$10^{14}M_\\odot$ cluster that started star formation at $z>12$." }, { "anchor": "Resolving the Hot Dust Disk of ESO323-G77: Infrared interferometry has fuelled a paradigm shift in our understanding of\nthe dusty structure in the central parsecs of Active Galactic Nuclei (AGN). The\ndust is now thought to comprise of a hot ($\\sim1000\\,$K) equatorial disk, some\nof which is blown into a cooler ($\\sim300\\,$K) polar dusty wind by radiation\npressure. In this paper, we utilise the new near-IR interferometer GRAVITY on\nthe Very Large Telescope Interferometer (VLTI) to study a Type 1.2 AGN hosted\nin the nearby Seyfert galaxy ESO323-G77. By modelling the squared visibility\nand closure phase, we find that the hot dust is equatorially extended,\nconsistent with the idea of a disk, and shows signs of asymmetry in the same\ndirection. Furthermore, the data is fully consistent with the hot dust size\ndetermined by K band reverberation mapping as well as the predicted size from a\nCAT3D-WIND model created in previous work using the SED of ESO323-G77 and\nobservations in the mid-IR from VLTI/MIDI.", "positive": "Herschel observations of gamma-ray burst host galaxies: implications for\n the topology of the dusty interstellar medium: Long-duration gamma-ray bursts (GRBs) are indisputably related to star\nformation, and their vast luminosity in gamma rays pin-points regions of star\nformation independent of galaxy mass. As such, GRBs provide a unique tool for\nstudying star forming galaxies out to high-z independent of luminosity. Most of\nour understanding of the properties of GRB hosts (GRBHs) comes from optical and\nnear-infrared (NIR) follow-up observations, and we therefore have relatively\nlittle knowledge of the fraction of dust-enshrouded star formation that resides\nwithin GRBHs. Currently ~20% of GRBs show evidence of significant amounts of\ndust along the line of sight to the afterglow through the host galaxy, and\nthese GRBs tend to reside within redder and more massive galaxies than GRBs\nwith optically bright afterglows. In this paper we present Herschel\nobservations of five GRBHs with evidence of being dust-rich, targeted to\nunderstand the dust attenuation properties within GRBs better. Despite the\nsensitivity of our Herschel observations, only one galaxy in our sample was\ndetected (GRBH 070306), for which we measure a total star formation rate (SFR)\nof ~100Mstar/yr, and which had a relatively high stellar mass\n(log[Mstar]=10.34+0.09/-0.04). Nevertheless, when considering a larger sample\nof GRBHs observed with Herschel, it is clear that stellar mass is not the only\nfactor contributing to a Herschel detection, and significant dust extinction\nalong the GRB sightline (A_{V,GRB}>1.5~mag) appears to be a considerably better\ntracer of GRBHs with high dust mass. This suggests that the extinguishing dust\nalong the GRB line of sight lies predominantly within the host galaxy ISM, and\nthus those GRBs with A_{V,GRB}>1~mag but with no host galaxy Herschel\ndetections are likely to have been predominantly extinguished by dust within an\nintervening dense cloud." }, { "anchor": "What is the role of stellar radiative feedback in setting the stellar\n mass spectrum?: In spite of decades of theoretical efforts, the physical origin of the\nstellar initial mass function (IMF) is still debated. Particularly crucial is\nthe question of what sets the peak of the distribution. To investigate this\nissue we perform high resolution numerical simulations with radiative feedback\nexploring in particular the role of the stellar and accretion luminosities. We\nalso perform simulations with a simple effective equation of state (eos) and we\ninvestigate 1000 solar mass clumps having respectively 0.1 and 0.4 pc of\ninitial radii. We found that most runs, both with radiative transfer or an eos,\npresent similar mass spectra with a peak broadly located around 0.3-0.5\nM$_\\odot$ and a powerlaw-like mass distribution at higher masses. However, when\naccretion luminosity is accounted for, the resulting mass spectrum of the most\ncompact clump tends to be moderately top-heavy. The effect remains limited for\nthe less compact one, which overall remains colder. Our results support the\nidea that rather than the radiative stellar feedback, this is the transition\nfrom the isothermal to the adiabatic regime, which occurs at a gas density of\nabout 10$^{10}$ cm$^{-3}$, that is responsible for setting the peak of the\ninitial mass function. This stems for the fact that $i)$ extremely compact\nclumps for which the accretion luminosity has a significant influence are very\nrare and $ii)$ because of the luminosity problem, which indicates that the\neffective accretion luminosity is likely weaker than expected.", "positive": "CLEAR: The Morphological Evolution of Galaxies in the Green Valley: Quiescent galaxies having more compact morphologies than star-forming\ngalaxies has been a consistent result in the field of galaxy evolution. What is\nnot clear is at what point this divergence happens, i.e. when do quiescent\ngalaxies become compact, and how big of a role does the progenitor effect play\nin this result? Here we aim to model the morphological and star-formation\nhistories of high redshift (0.8 $<$ z $<$ 1.65) massive galaxies\n(log(M/M$\\odot$) $>$ 10.2) with stellar population fits using HST/WFC3 G102 and\nG141 grism spectra plus photometry from the CLEAR (CANDELS Lyman-alpha Emission\nat Reionization) survey, constraining the star-formation histories for a sample\nof $\\sim$ 400 massive galaxies using flexible star-formation histories. We\ndevelop a novel approach to classifying galaxies by their formation activity in\na way that highlights the green valley population, by modeling the specific\nstar-formation rate distributions as a function of redshift and deriving the\nprobability that a galaxy is quiescent (PQ). Using PQ and our flexible\nstar-formation histories we outline the evolutionary paths of our galaxies in\nrelation to stellar mass, Sersic index, $R_{eff}$, and stellar mass surface\ndensity. We find that galaxies show no appreciable stellar mass growth after\nentering the green valley (a net decrease of 4$\\%$) while their stellar mass\nsurface densities increase by $\\sim$ 0.25 dex. Therefore galaxies are becoming\ncompact during the green valley and this is due to increases in Sersic index\nand decreases in $R_{eff}$." }, { "anchor": "The Sloan Digital Sky Survey Reverberation Mapping Project:\n Accretion-Disk Sizes from Continuum Lags: We present accretion-disk structure measurements from continuum lags in the\nSloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Lags are\nmeasured using the \\texttt{JAVELIN} software from the first-year SDSS-RM $g$\nand $i$ photometry, resulting in well-defined lags for 95 quasars, 33 of which\nhave lag SNR $>$ 2$\\sigma$. We also estimate lags using the \\texttt{ICCF}\nsoftware and find consistent results, though with larger uncertainties.\nAccretion-disk structure is fit using a Markov Chain Monte Carlo approach,\nparameterizing the measured continuum lags as a function of disk size\nnormalization, wavelength, black hole mass, and luminosity. In contrast with\nprevious observations, our best-fit disk sizes and color profiles are\nconsistent (within 1.5~$\\sigma$) with the \\citet{SS73} analytic solution. We\nalso find that more massive quasars have larger accretion disks, similarly\nconsistent with the analytic accretion-disk model. The data are inconclusive on\na correlation between disk size and continuum luminosity, with results that are\nconsistent with both no correlation and with the \\citet{SS73} expectation. The\ncontinuum lag fits have a large excess dispersion, indicating that our measured\nlag errors are underestimated and/or our best-fit model may be missing the\neffects of orientation, spin, and/or radiative efficiency. We demonstrate that\nfitting disk parameters using only the highest-SNR lag measurements biases\nbest-fit disk sizes to be larger than the disk sizes recovered using a Bayesian\napproach on the full sample of well-defined lags.", "positive": "The SCUBA-2 Cosmology Legacy Survey: The EGS deep field I - Deep number\n counts and the redshift distribution of the recovered Cosmic Infrared\n Background at 450 and 850 um: We present deep observations at 450 um and 850 um in the Extended Groth Strip\nfield taken with the SCUBA-2 camera mounted on the James Clerk Maxwell\nTelescope as part of the deep SCUBA-2 Cosmology Legacy Survey (S2CLS),\nachieving a central instrumental depth of $\\sigma_{450}=1.2$ mJy/beam and\n$\\sigma_{850}=0.2$ mJy/beam. We detect 57 sources at 450 um and 90 at 850 um\nwith S/N > 3.5 over ~70 sq. arcmin. From these detections we derive the number\ncounts at flux densities $S_{450}>4.0$ mJy and $S_{850}>0.9$ mJy, which\nrepresent the deepest number counts at these wavelengths derived using directly\nextracted sources from only blank-field observations with a single-dish\ntelescope. Our measurements smoothly connect the gap between previous shallower\nblank-field single-dish observations and deep interferometric ALMA results. We\nestimate the contribution of our SCUBA-2 detected galaxies to the cosmic\ninfrared background (CIB), as well as the contribution of 24 um-selected\ngalaxies through a stacking technique, which add a total of $0.26\\pm0.03$ and\n$0.07\\pm0.01$ MJy/sr, at 450 um and 850 um, respectively. These surface\nbrightnesses correspond to $60\\pm20$ and $50\\pm20$ per cent of the total CIB\nmeasurements, where the errors are dominated by those of the total CIB. Using\nthe photometric redshifts of the 24 um-selected sample and the redshift\ndistributions of the submillimetre galaxies, we find that the redshift\ndistribution of the recovered CIB is different at each wavelength, with a peak\nat $z\\sim1$ for 450 um and at $z\\sim2$ for 850um, consistent with previous\nobservations and theoretical models." }, { "anchor": "Search for and Identification of Young Compact Galactic Supernova\n Remnants Using THOR: Young Supernova remnants (SNRs) with smaller angular sizes are likely missing\nfrom existing radio SNR catalogues, caused by observational constraints and\nselection effects. In order to find new compact radio SNR candidates, we\nsearched the high angular resolution (25\") THOR radio survey of the first\nquadrant of the galaxy. We selected sources with non-thermal radio spectra. HI\nabsorption spectra and channel maps were used to identify which sources are\ngalactic and to estimate their distances. Two new compact SNRs were found:\nG31.299$-$0.493 and G18.760$-$0.072, of which the latter was a previously\nsuggested SNR candidate. The distances to these SNRs are 5.0 $\\pm$ 0.3 kpc and\n4.7 $\\pm$ 0.2 kpc, respectively. Based on the SN rate in the galaxy or on the\nstatistics of known SNRs, we estimate that there are 15$-$20 not yet detected\ncompact SNRs in the galaxy and that the THOR survey area should contain three\nor four. Our detection of two SNRs (half the expected number) is consistent\nwith the THOR sensitivity limit compared with the distribution of integrated\nflux densities of SNRs.", "positive": "The cosmic UV background and the beginning and end of star formation in\n simulated field dwarf galaxies: We use the APOSTLE cosmological simulations to examine the role of the cosmic\nUV background in regulating star formation (SF) in low-mass LCDM halos. In\nagreement with earlier work, we find that after reionization SF proceeds mainly\nin halos whose mass exceeds a redshift-dependent ``critical'' mass, Mcrit, set\nby the structure of the halos and by the thermal pressure of UV-heated gas.\nMcrit increases from ~10^8 Msun at z~10 to Mcrit ~10^9.7 Msun at z=0, roughly\nfollowing the average mass growth of halos in that mass range. This implies\nthat halos well above or below critical at present have remained so since early\ntimes. Halos of luminous dwarfs today were already above-critical and\nstar-forming at high redshift, explaining naturally the ubiquitous presence of\nancient stellar populations in dwarfs, regardless of luminosity. The SF history\nof systems close to the critical boundary is more complex. SF may cease or\nreignite in dwarfs whose host halo falls below or climbs above the critical\nboundary, suggesting an attractive explanation for the episodic nature of SF in\nsome dwarfs. Also, some subcritical halos today may have been above critical in\nthe past; these systems should at present make up a sizable population of faint\nfield dwarfs lacking ongoing star formation. Although few such galaxies are\ncurrently known, the discovery of this population would provide strong support\nfor our results. Our work indicates that, rather than stellar feedback, it is\nthe ionizing UV background and mass accretion history what regulates SF in the\nfaintest dwarfs." }, { "anchor": "If dark matter is fuzzy, the first stars form in massive pancakes: Fuzzy dark matter (FDM) is a proposed modification for the standard cold dark\nmatter (CDM) model motivated by small-scale discrepancies in low-mass galaxies.\nComposed of ultra-light (mass $\\sim 10^{-22}$ eV) axions with kpc-scale de\nBroglie wavelengths, this is one of a class of candidates that predicts that\nthe first collapsed objects form in relatively massive dark matter halos. This\nimplies that the formation history of the first stars and galaxies would be\nvery different, potentially placing strong constraints on such models. Here we\nnumerically simulate the formation of the first stars in an FDM cosmology,\nfollowing the collapse in a representative volume all the way down to\nprimordial protostar formation including a primordial non-equilibrium chemical\nnetwork and cooling for the first time. We find two novel results: first, the\nlarge-scale collapse results in a very thin and flat gas \"pancake\"; second,\ndespite the very different cosmology, this pancake fragments until it forms\nprotostellar objects indistinguishable from those in CDM. Combined, these\nresults indicate that the first generation of stars in this model are also\nlikely to be massive and, because of the sheet morphology, do not\nself-regulate, resulting in a massive Pop III starburst. We estimate the total\nnumber of first stars forming in this extended structure to be $10^4$ over 20\nMyr using a simple model to account for the ionizing feedback from the stars,\nand should be observable with JWST. These predictions provide a potential\nsmoking gun signature of FDM and similar dark matter candidates.", "positive": "L1448-MM observations by the Herschel Key program, \"Dust, Ice, and Gas\n In Time\" (DIGIT): We present Herschel/PACS observations of L1448-MM, a Class 0 protostar with a\nprominent outflow. Numerous emission lines are detected at 55 < lambda < 210\nmicrometer including CO, OH, H2O, and [O I]. We investigate the spatial\ndistribution of each transition to find that lines from low energy levels tend\nto distribute along the outflow direction while lines from high energy levels\npeak at the central spatial pixel. Spatial maps reveal that OH emission lines\nare formed in a relatively small area, while [O I] emission is extended.\nAccording to the rotational diagram analysis, the CO emission can be fitted by\ntwo (warm and hot) temperature components. For H2O, the ortho-to-para ratio is\nclose to 3. The non-LTE LVG calculations suggest that CO and H2O lines could\ninstead be formed in a high kinetic temperature (T > 1000 K) environment,\nindicative of a shock origin. For OH, IR-pumping processes play an important\nrole in the level population. The molecular emission in L1448-MM is better\nexplained with a C-shock model, but the atomic emission of PACS [O I] and\nSpitzer/IRS [Si II] emission is not consistent with C-shocks, suggesting\nmultiple shocks in this region. Water is the major line coolant of L1448-MM in\nthe PACS wavelength range, and the best-fit LVG models predict that H2O and CO\nemit (50-80)% of their line luminosity in the PACS wavelength range." }, { "anchor": "The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk\n Anisotropy: Quasar luminosity functions are a fundamental probe of the growth and\nevolution of supermassive black holes. Measuring the intrinsic luminosity\nfunction is difficult in practice, due to a multitude of observational and\nsystematic effects. As sample sizes increase and measurement errors drop,\ncharacterizing the systematic effects is becoming more important. It is well\nknown that the continuum emission from the accretion disk of quasars is\nanisotropic --- in part due to its disk-like structure --- but current\nluminosity function calculations effectively assume isotropy over the range of\nunobscured lines of sight. Here, we provide the first steps in characterizing\nthe effect of random quasar orientations and simple models of anisotropy on\nobserved luminosity functions. We find that the effect of orientation is not\ninsignificant and exceeds other potential corrections such as those from\ngravitational lensing of foreground structures. We argue that current\nobservational constraints may overestimate the intrinsic luminosity function by\nas much as a factor of ~2 on the bright end. This has implications for models\nof quasars and their role in the Universe, such as quasars' contribution to\ncosmological backgrounds.", "positive": "Exploring Simulated Early Star Formation in the Context of the\n Ultrafaint Dwarf Galaxies: Ultrafaint dwarf galaxies (UFDs) are typically assumed to have simple,\nstellar populations with star formation ending at reionization. Yet as the\nobservations of these galaxies continue to improve, their star formation\nhistories (SFHs) are revealed to be more complicated than previously thought.\nIn this paper, we study how star formation, chemical enrichment, and mixing\nproceed in small, dark matter halos at early times using a high-resolution,\ncosmological, hydrodynamical simulation. The goals are to inform the future use\nof analytic models and to explore observable properties of the simulated halos\nin the context of UFD data. Specifically, we look at analytic approaches that\nmight inform metal enrichment within and beyond small galaxies in the early\nUniverse. We find that simple assumptions for modeling the extent of\nsupernova-driven winds agree with the simulation on average whereas\ninhomogeneous mixing and gas flows have a large effect on the spread in\nsimulated stellar metallicities. In the context of the UFDs, this work\ndemonstrates that simulations can form halos with a complex SFH and a large\nspread in the metallicity distribution function within a few hundred Myr in the\nearly Universe. In particular, bursty and continuous star formation are seen in\nthe simulation and both scenarios have been argued from the data. Spreads in\nthe simulated metallicities, however remain too narrow and too metal-rich when\ncompared to the UFDs. Future work is needed to help reduce these discrepancies\nand advance our interpretation of the data." }, { "anchor": "Stellar hydrodynamical modeling of dwarf galaxies: simulation\n methodology, tests, and first results: Cosmological simulations still lack numerical resolution or physical\nprocesses to simulate dwarf galaxies in sufficient details. Accurate numerical\nsimulations of individual dwarf galaxies are thus still in demand. We aim at\n(i) studying in detail the coupling between stars and gas in a galaxy,\nexploiting the so-called stellar hydrodynamical approach, and (ii) studying the\nchemo-dynamical evolution of individual galaxies starting from\nself-consistently calculated initial gas distributions. We present a novel\nchemo-dynamical code in which the dynamics of gas is computed using the usual\nhydrodynamics equations, while the dynamics of stars is described by the\nstellar hydrodynamics approach, which solves for the first three moments of the\ncollisionless Boltzmann equation. The feedback from stellar winds and dying\nstars is followed in detail. In particular, a novel and detailed approach has\nbeen developed to trace the aging of various stellar populations, which enables\nan accurate calculation of the stellar feedback depending on the stellar age.\nWe build initial equilibrium models of dwarf galaxies that take gas\nself-gravity into account and present different levels of rotational support.\nModels with high rotational support develop prominent bipolar outflows; a\nnewly-born stellar population in these models is preferentially concentrated to\nthe galactic midplane. Models with little rotational support blow away a large\nfraction of the gas and the resulting stellar distribution is extended and\ndiffuse. The stellar dynamics turns out to be a crucial aspect of galaxy\nevolution. If we artificially suppress stellar dynamics, supernova explosions\noccur in a medium heated and diluted by the previous activity of stellar winds,\nthus artificially enhancing the stellar feedback (abridged).", "positive": "The Pristine Survey -- VI. The first three years of medium-resolution\n follow-up spectroscopy of Pristine EMP star candidates: We present the results of a 3-year long, medium-resolution spectroscopic\ncampaign aimed at identifying very metal-poor stars from candidates selected\nwith the CaHK, metallicity-sensitive Pristine survey. The catalogue consists of\na total of 1007 stars, and includes 146 rediscoveries of metal-poor stars\nalready presented in previous surveys, 707 new very metal-poor stars with\n[Fe/H] < -2.0, and 95 new extremely metal-poor stars with [Fe/H] < -3.0. We\nprovide a spectroscopic [Fe/H] for every star in the catalogue, and [C/Fe]\nmeasurements for a subset of the stars (10% with [Fe/H] < -3 and 24% with -3 <\n[Fe/H] < -2) for which a carbon determination is possible, contingent mainly on\nthe carbon abundance, effective temperature and S/N of the stellar spectra. We\nfind an average carbon enhancement fraction ([C/Fe] >= +0.7) of 41 +- 4% for\nstars with -3 < [Fe/H] < -2 and 58 +- 14% for stars with [Fe/H] < -3, and\nreport updated success rates for the Pristine survey of 56 % and 23 % to\nrecover stars with [Fe/H] < -2.5 and [Fe/H] < -3, respectively. Finally, we\ndiscuss the current status of the survey and its preparation for providing\ntargets to upcoming multi-object spectroscopic surveys such as WEAVE." }, { "anchor": "First deep search of tidal tails in the Milky Way globular cluster NGC\n 6362: I present results of the analysis of a set of images obtained in the field of\nthe Milky Way globular cluster NGC 6362 using the Dark Energy Camera, which is\nmounted in the 4.0m Victor Blanco telescope of the Cerro-Tololo Interamerican\nobservatory. The cluster was selected as a science case for deep high-quality\nphotometry because of the controversial observational findings and theoretical\npredictions on the existence of cluster tidal tails. The collected data allowed\nus to build an unprecedented deep cluster field color-magnitude diagram, from\nwhich I filtered stars to produce a stellar density map, to trace the stellar\ndensity variation as a function of the position angle for different concentric\nannulii centered on the cluster, and to construct a cluster stellar density\nradial profile. I also built a stellar density map from a synthetic\ncolor-magnitude diagram generated from a model of the stellar population\ndistribution in the Milky Way. All the analysis approached converge toward a\nrelatively smooth stellar density between 1 and $\\sim$ 3.8 cluster Jacobi\nradii, with a slightly difference smaller than 2 times the background stellar\ndensity fluctuation between the mean stellar density of the south-eastern and\nthat of north-western hemispheres, the latter being higher. Moreover, the\nspatial distribution of the recently claimed tidal tail stars agrees well not\nonly with the observed composite star field distribution, but also with the\nregion least affected by interstellar absorption. Nevertheless, I detected a\nlow stellar density excess around the cluster Jacobi radius, from which I\nconclude that NGC 6362 present a thin extra tidal halo.", "positive": "The Impact of Binaries on the Stellar Initial Mass Function: (abridged) The stellar initial mass function (IMF) can be conveniently\nrepresented as a canonical two-part power law function and is largely invariant\nfor star formation regions evident in the Local Group of galaxies. The IMF is a\nhilfskonstrukt. It is a mathematical formulation of an idealised population of\nstars formed together in one star formation event. The nature of the IMF (is it\na probability density or an optimal sampling distribution function?) is raised.\nBinary stars, if unresolved, have a very significant influence at low stellar\nmasses. Especially important is to take care of the changing binary fraction as\na result of stellar-dynamical evolution of the embedded clusters which spawn\nthe field populations of galaxies, given that the binary fraction at birth is\nvery high and independent of primary-star mass. The high multiplicity fraction\namongst massive stars leads to a substantial fraction of these being ejected\nout of their birth clusters and to massive stars merging. This explains the\ntop-lightness of the IMF in star clusters in M31. In close binaries also the\nmasses of the components can be changed due to mass transfer. A large amount of\nevidence points to the IMF becoming top-heavy with decreasing metallicity and\nabove a star-formation-rate density of about 0.1 Msun/(pc^3 yr) of the\ncluster-forming cloud core. This is also indicated through the observed\nsupernova rates in star-bursting galaxies. At the same time, the IMF may be\nbottom light at low metallicity and bottom-heavy at high metallicity, possibly\naccounting for the results on elliptical galaxies and ultra-faint dwarf\ngalaxies, respectively." }, { "anchor": "The H_2O southern Galactic Plane Survey (HOPS): I. Techniques and H_2O\n maser data: We present first results of the H_2O Southern Galactic Plane Survey (HOPS),\nusing the Mopra radiotelescope with a broad band backend and a beam size of\nabout 2'. We have observed 100 square degrees of the southern Galactic plane at\n12mm (19.5 to 27.5GHz), including spectral line emission from water masers,\nmultiple metastable transitions of ammonia, cyanoacetylene, methanol and radio\nrecombination lines. In this paper, we report on the characteristics of the\nsurvey and water maser emission. We find 540 water masers, of which 334 are new\ndetections. The strongest maser is 3933Jy and the weakest is 0.7Jy, with 62\nmasers over 100Jy. In 14 maser sites, the spread in velocity of the water maser\nemission exceeds 100km/s. In one region, the water maser velocities are\nseparated by 351.3km/s. The rms noise levels are typically between 1-2Jy, with\n95% of the survey under 2Jy. We estimate completeness limits of 98% at around\n8.4Jy and 50% at around 5.5Jy. We estimate that there are between 800 and 1500\nwater masers in the Galaxy that are detectable in a survey with similar\ncompleteness limits to HOPS. We report possible masers in NH_3 (11,9) and (8,6)\nemission towards G19.61-0.23 and in the NH_3 (3,3) line towards G23.33-0.30.", "positive": "Science with the Galactic O-Star Spectroscopic Survey (GOSSS) : The\n relationship between DIBs, ISM, and extinction: In this poster we show our preliminary analysis of DIBs (Diffuse Interstellar\nBands) and other interstellar absorption lines with the purpose of\nunderstanding their origin and their relationship with extinction. We use the\nbiggest Galactic O-star blue-violet spectroscopic sample ever (GOSSS, see\ncontribution by Ma\\'iz Apell\\'aniz at this meeting). This sample allows a new\ninsight on this topic because of the adequacy of O-star spectra, the sample\nnumber (700 and increasing, 400 used here), and their distribution in the MW\ndisk. We confirm the high correlation coefficients between different DIBs and\nE(B - V), though the detailed behavior of each case shows small differences. We\nalso detect a moderately low correlation coefficient between Ca II\n{\\lambda}3934 (Ca K) and E(B - V) with a peculiar spatial distribution that we\nascribe to the relationship between line saturation and velocity profiles for\nCa II {\\lambda}3934." }, { "anchor": "The MASSIVE Survey - VII. The Relationship of Angular Momentum, Stellar\n Mass and Environment of Early-Type Galaxies: We analyse the environmental properties of 370 local early-type galaxies\n(ETGs) in the MASSIVE and ATLAS3D surveys, two complementary volume-limited\nintegral-field spectroscopic (IFS) galaxy surveys spanning absolute $K$-band\nmagnitude $-21.5 > M_K > -26.6$, or stellar mass $8 \\times 10^{9} < M_* < 2\n\\times 10^{12} M_\\odot$. We find these galaxies to reside in a diverse range of\nenvironments measured by four methods: group membership (whether a galaxy is a\nbrightest group/cluster galaxy, satellite, or isolated), halo mass, large-scale\nmass density (measured over a few Mpc), and local mass density (measured within\nthe $N$th neighbour). The spatially resolved IFS stellar kinematics provide\nrobust measurements of the spin parameter $\\lambda_e$ and enable us to examine\nthe relationship among $\\lambda_e$, $M_*$, and galaxy environment. We find a\nstrong correlation between $\\lambda_e$ and $M_*$, where the average $\\lambda_e$\ndecreases from $\\sim 0.4$ to below 0.1 with increasing mass, and the fraction\nof slow rotators $f_{\\rm slow}$ increases from $\\sim 10$% to 90%. We show for\nthe first time that at fixed $M_*$, there are almost no trends between galaxy\nspin and environment; the apparent kinematic morphology-density relation for\nETGs is therefore primarily driven by $M_*$ and is accounted for by the joint\ncorrelations between $M_*$ and spin, and between $M_*$ and environment. A\npossible exception is that the increased $f_{\\rm slow}$ at high local density\nis slightly more than expected based only on these joint correlations. Our\nresults suggest that the physical processes responsible for building up the\npresent-day stellar masses of massive galaxies are also very efficient at\nreducing their spin, in any environment.", "positive": "Local galaxies with compact cores as the possible descendants of massive\n compact quiescent galaxies at high redshift: In order to test a possible evolutionary scenario of high-$z$ compact\nquiescent galaxies (cQGs) that they can survive as local compact cores embedded\nin local massive galaxies with different morphology classes, we explore the\nstar formation histories of local compact cores according to their spectral\nanalysis. We build a sample of 182 massive galaxies with compact cores\n(${M}_{*,{\\rm core}} > 10^{10.6} {\\rm M}_\\odot$) at $0.02 \\leq z \\leq 0.06$\nfrom SDSS DR7 spectroscopic catalogue. STARLIGHT package is used to analyze the\nmedian stacked spectra and derive the stellar ages and metallicities. Our main\nresults show that local compact cores have the average age of about\n$12.1\\pm0.6$ Gyr, indicating their early formation at $z > 3$, which is\nconsistent with the formation redshifts of cQGs at $1 80\\%$) will evolve into\nlocal massive ETGs according to dry minor merger, while some of them ($\\sim\n15\\%$) will build a substantial stellar/gas discs according to the late-time\ngas accretion and sustaining star formation, and finally grow up to spiral\ngalaxies." }, { "anchor": "RDM-stars and related topics: In this paper, we will continue to study the model of black holes coupled to\nthe radial flows of dark matter (RDM-stars). According to recent studies, this\nmodel well describes the experimental Rotation Curves (RCs) of spiral galaxies,\nalso, RDM-stars can produce signals with the characteristics of Fast Radio\nBursts (FRBs). In this paper, we will perform a combined analysis of\nexperimental data on RCs and FRBs, which will allow to constrain tighter\nparameters of the model. We will also show that within the framework of the\nmodel, the Tully-Fisher relation with a slope of $ \\beta = 3-4 $ can be\nobtained. Further, several particular solutions will be considered: tachyonic\noven -- a solution in which the incoming flow of tachyons turns into an\noutgoing flow of massive particles; shell condensate -- a naked singularity of\nnegative mass covered by a thin shell of positive mass, so that the\nSchwarzschild solution of negative mass inside is joined to one of positive\nmass outside; also, an RDM solution with a cosmological constant will be\nconsidered. Further, in the model under consideration, Penrose diagrams will be\nconstructed, which share common features with Schwarzschild solutions of\npositive and negative mass, whose combination the model is. The mechanism of\neffective formation of negative masses in the model is discussed, which is\nactivated when the density of the central core exceeds the Planck value,\nsimilarly to the previously studied quantum bounce effect.", "positive": "The local black hole mass function derived from the M_{BH}-P and the\n M_{BH}-n relations: We present a determination of the supermassive black hole (SMBH) mass\nfunction for early- and late-type galaxies in the nearby universe (z<0.0057),\nestablished from a volume-limited sample consisting of a statistically complete\ncollection of the brightest spiral galaxies in the southern hemisphere. The\nsample is defined by limiting luminosity (redshift-independent) distance,\nD_L=25.4 Mpc, and a limiting absolute B-band magnitude, M_B=-19.12. These\nlimits define a sample of 140 spiral, 30 elliptical (E), and 38 lenticular (S0)\ngalaxies. We established the Sersic index distribution for early-type (E/S0)\ngalaxies in our sample. Davis et al. (2014) established the pitch angle\ndistribution for their sample, which is identical to our late-type (spiral)\ngalaxy sample. We then used the pitch angle and the Sersic index distributions\nin order to estimate the SMBH mass function for our volume-limited sample. The\nobservational simplicity of our approach relies on the empirical relation\nbetween the mass of the central (SMBH) and the Sersic index (Graham et al.\n2007) for an early-type galaxy or the logarithmic spiral arm pitch angle\n(Berrier et al. 2013) for a spiral galaxy. Our SMBH mass function agrees well\nat the high-mass end with previous values in the literature. At the low-mass\nend, while inconsistencies exist in previous works that still need to be\nresolved, our work is more in line with expectations based on modeling of black\nhole evolution." }, { "anchor": "Peeping into recent star formation history of the Magellanic Clouds: Here, we study the distribution of Fundamental-mode Cepheids in the\nMagellanic Cloud as a function of their positions and ages using the data from\nthe OGLE~IV survey. Age of the Cepheids are determined through well known\nperiod - age relations for the LMC and SMC Cepheids which are used to\nunderstand the star formation scenario in the Magellanic Cloud. The age\ndistributions of the Cepheids in LMC and SMC show peak around $155^{+45}_{-35}$\nMyr and $224^{+51}_{-42}$ Myr, respectively. This indicates that a major star\nformation event took place in the Magellanic Cloud at about 200\\,Myr ago. It is\nbelieved that this event might have been triggered by a close encounter between\nthe two components of the Magellanic Cloud or due to a possible tidal\ninteraction between the Magellanic Cloud and Milky Way galaxy during one of its\npericentric passages round the Milky Way. Cepheids are found to be\nasymmetrically distributed in both the LMC and SMC. A high-density clumpy\nstructure is found to be located towards eastern side of the LMC and south-west\ndirection of the SMC from their respective galactic centres.", "positive": "The Fundamentally Different Dynamics of Dust and Gas in Molecular Clouds: We study the behavior of large dust grains in turbulent molecular clouds\n(MCs). In primarily neutral regions, dust grains move as aerodynamic particles,\nnot necessarily with the gas. We therefore directly simulate, for the first\ntime, the behavior of aerodynamic grains in highly supersonic,\nmagnetohydrodynamic turbulence typical of MCs. We show that, under these\nconditions, grains with sizes a >0.01 micron exhibit dramatic (exceeding factor\n~1000) fluctuations in the local dust-to-gas ratio (implying large small-scale\nvariations in abundances, dust cooling rates, and dynamics). The dust can form\nhighly filamentary structures (which would be observed in both dust emission\nand extinction), which can be much thinner than the characteristic width of gas\nfilaments. Sometimes, the dust and gas filaments are not even in the same\nlocation. The 'clumping factor' of the dust (critical for dust\ngrowth/coagulation/shattering) can reach ~100, for grains in the ideal size\nrange. The dust clustering is maximized around scales ~0.2pc*(a/micron)*(100\ncm^-3/n_gas), and is 'averaged out' on larger scales. However, because the\ndensity varies widely in supersonic turbulence, the dynamic range of scales\n(and interesting grain sizes) for these fluctuations is much broader than in\nthe subsonic case. Our results are applicable to MCs of essentially all sizes\nand densities, but we note how Lorentz forces and other physics (neglected\nhere) may change them in some regimes. We discuss the potentially dramatic\nconsequences for star formation, dust growth and destruction, and dust-based\nobservations of MCs." }, { "anchor": "Emulating Radiative Transfer with Artificial Neural Networks: Forward-modeling observables from galaxy simulations enables direct\ncomparisons between theory and observations. To generate synthetic spectral\nenergy distributions (SEDs) that include dust absorption, re-emission, and\nscattering, Monte Carlo radiative transfer is often used in post-processing on\na galaxy-by-galaxy basis. However, this is computationally expensive,\nespecially if one wants to make predictions for suites of many cosmological\nsimulations. To alleviate this computational burden, we have developed a\nradiative transfer emulator using an artificial neural network (ANN),\nANNgelina, that can reliably predict SEDs of simulated galaxies using a small\nnumber of integrated properties of the simulated galaxies: star formation rate,\nstellar and dust masses, and mass-weighted metallicities of all star particles\nand of only star particles with age <10 Myr. Here, we present the methodology\nand quantify the accuracy of the predictions. We train the ANN on SEDs computed\nfor galaxies from the IllustrisTNG project's TNG50 cosmological\nmagnetohydrodynamical simulation. ANNgelina is able to predict the SEDs of\nTNG50 galaxies in the ultraviolet (UV) to millimetre regime with a typical\nmedian absolute error of ~7 per cent. The prediction error is the greatest in\nthe UV, possibly due to the viewing-angle dependence being greatest in this\nwavelength regime. Our results demonstrate that our ANN-based emulator is a\npromising computationally inexpensive alternative for forward-modeling galaxy\nSEDs from cosmological simulations.", "positive": "How the First Stars Regulated Star Formation. II. Enrichment by Nearby\n Supernovae: Metals from Population III (Pop III) supernovae led to the formation of less\nmassive Pop II stars in the early universe, altering the course of evolution of\nprimeval galaxies and cosmological reionization. There are a variety of\nscenarios in which heavy elements from the first supernovae were taken up into\nsecond-generation stars, but cosmological simulations only model them on the\nlargest scales. We present small-scale, high-resolution simulations of the\nchemical enrichment of a primordial halo by a nearby supernova after partial\nevaporation by the progenitor star. We find that ejecta from the explosion\ncrash into and mix violently with ablative flows driven off the halo by the\nstar, creating dense, enriched clumps capable of collapsing into Pop II stars.\nMetals may mix less efficiently with the partially exposed core of the halo, so\nit might form either Pop III or Pop II stars. Both Pop II and III stars may\nthus form after the collision if the ejecta do not strip all the gas from the\nhalo. The partial evaporation of the halo prior to the explosion is crucial to\nits later enrichment by the supernova." }, { "anchor": "LOFAR discovery and wide-band characterisation of an ultra-steep\n spectrum AGN radio remnant associated with Abell 1318: We present the discovery of a very extended (550 kpc) and\nlow-surface-brightness ($ 3.3 \\mu \\mathrm{Jy} \\, arcsec^{-2} $ at 144 MHz)\nradio emission region in Abell 1318. These properties are consistent with its\ncharacterisation as an active galactic nucleus (AGN) remnant radio plasma,\nbased on its morphology and radio spectral properties. We performed a\nbroad-band (54 - 1400 MHz) radio spectral index and curvature analysis using\nLOFAR, uGMRT, and WSRT-APERTIF data. We also derived the radiative age of the\ndetected emission, estimating a maximum age of 250 Myr. The morphology of the\nsource is remarkably intriguing, with two larger, oval-shaped components and a\nthinner, elongated, and filamentary structure in between, plausibly reminiscent\nof two aged lobes and a jet. Based on archival {\\it Swift} as well as SDSS data\nwe performed an X-ray and optical characterisation of the system, whose virial\nmass was estimated to be $ \\sim 7.4 \\times 10^{13} \\, \\mathrm{M} _{\\odot}$.\nThis places A1318 in the galaxy group regime. Interestingly, the radio source\ndoes not have a clear optical counterpart embedded in it, thus, we propose that\nit is most likely an unusual AGN remnant of previous episode(s) of activity of\nthe AGN hosted by the brightest group galaxy ($ \\sim 2.6 \\times 10^{12} \\,\n\\mathrm{M} _{\\odot}$), which is located at a projected distance of $\\sim$170\nkpc in the current epoch. This relatively high offset may be a result of IGrM\nsloshing sourced by a minor merger. The filamentary morphology of the source\nmay suggest that the remnant plasma has been perturbed by the system dynamics,\nhowever, only future deeper X-ray observations will be able to address this\nquestion.", "positive": "The MOSDEF Survey: No Significant Enhancement in Star Formation or\n Deficit in Metallicity in Merging Galaxy Pairs at 1.5<=z<=3.5: We study the properties of 30 spectroscopically-identified pairs of galaxies\nobserved during the peak epoch of star formation in the universe. These systems\nare drawn from the MOSFIRE Deep Evolution Field (MOSDEF) Survey at $1.4 \\leq z\n\\leq 3.8$, and are interpreted as early-stage galaxy mergers. Galaxy pairs in\nour sample are identified as two objects whose spectra were collected on the\nsame Keck/MOSFIRE spectroscopic slit. Accordingly, all pairs in the sample have\nprojected separations $R_{{\\rm proj}}\\leq 60$ kpc. The velocity separation for\npairs was required to be $\\Delta v \\leq 500 \\mbox{ km s}^{-1}$, which is a\nstandard threshold for defining interacting galaxy pairs at low redshift.\nStellar mass ratios in our sample range from 1.1 to 550, with 12 ratios closer\nthan or equal to 3:1, the common definition of a \"major merger.\" Studies of\nmerging pairs in the local universe indicate anenhancement in star-formation\nactivity and deficit in gas-phase oxygen abundance relative to isolated\ngalaxies of the same mass. We compare the MOSDEF pairs sample to a control\nsample of isolated galaxies at the same redshift, finding no measurable SFR\nenhancement or metallicity deficit at fixed stellar mass for the pairs sample.\nThe lack of significant difference between the average properties of pairs and\ncontrol samples appears in contrast to results from low-redshift studies,\nalthough the small sample size and lower signal-to-noise of the high-redshift\ndata limit definitive conclusions on redshift evolution. These results are\nconsistent with some theoretical works suggesting a reduced differential effect\nof pre-coalescence mergers on galaxy properties at high redshift --\nspecifically that pre-coalescence mergers do not drive strong starbursts." }, { "anchor": "The wobbly Galaxy: kinematics north and south with RAVE red clump giants: The RAVE survey, combined with proper motions and distance estimates, can be\nused to study in detail stellar kinematics in the extended solar neighbourhood\n(solar suburb). Using the red clump, we examine the mean velocity components in\n3D between an R of 6 and 10 kpc and a Z of -2 to 2 kpc, concentrating on\nNorth-South differences. Simple parametric fits to the R, Z trends for VPHI and\nthe velocity dispersions are presented. We confirm the recently discovered\ngradient in mean Galactocentric radial velocity, VR, finding that the gradient\nis more marked below the plane, with a Z gradient also present. The vertical\nvelocity, VZ, also shows clear structure, with indications of a\nrarefaction-compression pattern, suggestive of wave-like behaviour. We perform\na rigorous error analysis, tracing sources of both systematic and random\nerrors. We confirm the North-South differences in VR and VZ along the\nline-of-sight, with the VR estimated independent of the proper motions. The\ncomplex three-dimensional structure of velocity space presents challenges for\nfuture modelling of the Galactic disk, with the Galactic bar, spiral arms and\nexcitation of wave-like structures all probably playing a role.", "positive": "Central wavelengths and profile shapes of diffuse interstellar bands vs.\n physical parameters of intervening clouds: This paper tries to establish whether there are variations of the central\nwavelengths or the profile shapes of diffuse interstellar bands (DIBs) and\nwhether these variations are caused by different physical parameters of\ntranslucent clouds.\n For this purpose we used spectra of two stars seen through two different\nsingle clouds: HD34078 (AE Aur) \\& HD73882 acquired using\n two different instruments: the MIKE spectrograph, fed with the 6.5 m Magellan\ntelescope at Las Campanas Observatory, and the UVES, fed with the 8 m Kueyen\ntelescope at the Paranal observatory. The wavelength displacements of the DIBs\nat 6196, 6203, 6376, 6379 and 6614 \\AA\\ with respect to the well known\ninterstellar atomic and molecular lines (K{\\sc i} and CH) have been measured.\nThe mentioned shift is seemingly absent in the DIBs at 4726, 4964, 4763, and\n4780 \\AA. In addition the considered profiles may show (in HD34078) extended\nred wings. The observed phenomena are likely related to physical parameters of\nintervening clouds (rotational temperatures of molecular species) and may help\nin the identification of the DIB carriers." }, { "anchor": "Chemical Evolution of HC3N in Dense Molecular Clouds: We investigated the chemical evolution of HC3N in six dense molecular clouds,\nusing archival available data from the Herschel infrared Galactic Plane Survey\n(Hi-GAL) and the Millimeter Astronomy Legacy Team Survey at 90 GHz (MALT90).\nRadio sky surveys of the Multi-Array Galactic Plane Imaging Survey (MAGPIS) and\nthe Sydney University Molonglo Sky Survey (SUMSS) indicate these dense\nmolecular clouds are associated with ultracompact HII (UCHII) regions and/or\nclassical HII regions. We find that in dense molecular clouds associated with\nnormal classical HII regions, the abundance of HC3N begins to decrease or\nreaches a plateau when the dust temperature gets hot. This implies UV photons\ncould destroy the molecule of HC3N. On the other hand, in the other dense\nmolecular clouds associated with UCHII regions, we find the abundance of HC3N\nincreases with dust temperature monotonously, implying HC3N prefers to be\nformed in warm gas. We also find that the spectra of HC3N (10-9) in\nG12.804-0.199 and RCW 97 show wing emissions, and the abundance of HC3N in\nthese two regions increases with its nonthermal velocity width, indicating HC3N\nmight be a shock origin species. We further investigated the evolutionary trend\nof N(N2H+)/N(HC3N) column density ratio, and found this ratio could be used as\na chemical evolutionary indicator of cloud evolution after the massive star\nformation is started.", "positive": "A Comprehensive Study of Broad Absorption Line Quasars: I. Prevalence of\n HeI* Absorption Line Multiplets in Low-Ionization Objects: Neutral Helium multiplets, HeI*3189,3889,10830 are very useful diagnostics to\nthe geometry and physical conditions of the absorbing gas in quasars. So far\nonly a handful of HeI* detections have been reported. Using a newly developed\nmethod, we detected HeI*3889 absorption line in 101 sources of a well-defined\nsample of 285 MgII BAL quasars selected from the SDSS DR5. This has increased\nthe number of HeI* BAL quasars by more than one order of magnitude. We further\ndetected HeI*3189 in 50% (52/101) quasars in the sample. The detection fraction\nof HeI* BALs in MgII BAL quasars is about 35% as a whole, and increases\ndramatically with increasing spectral signal-to-noise ratios, from 18% at S/N\n<= 10 to 93% at S/N >= 35. This suggests that HeI* BALs could be detected in\nmost MgII LoBAL quasars, provided spectra S/N is high enough. Such a\nsurprisingly high HeI* BAL fraction is actually predicted from photo-ionization\ncalculations based on a simple BAL model. The result indicates that HeI*\nabsorption lines can be used to search for BAL quasars at low-z, which cannot\nbe identified by ground-based optical spectroscopic survey with commonly seen\nUV absorption lines. Using HeI*3889, we discovered 19 BAL quasars at z<0.3 from\navailable SDSS spectral database. The fraction of HeI* BAL quasars is similar\nto that of LoBAL objects." }, { "anchor": "The Auriga Stellar Haloes: Connecting stellar population properties with\n accretion and merging history: We examine the stellar haloes of the Auriga simulations, a suite of thirty\ncosmological magneto-hydrodynamical high-resolution simulations of Milky\nWay-mass galaxies performed with the moving-mesh code AREPO. We study halo\nglobal properties and radial profiles out to $\\sim 150$ kpc for each individual\ngalaxy. The Auriga haloes are diverse in their masses and density profiles;\nmean metallicity and metallicity gradients; ages; and shapes, reflecting the\nstochasticity inherent in their accretion and merger histories. A comparison\nwith observations of nearby late-type galaxies shows very good agreement\nbetween most observed and simulated halo properties. However, Auriga haloes are\ntypically too massive. We find a connection between population gradients and\nmass assembly history: galaxies with few significant progenitors have more\nmassive haloes, possess large negative halo metallicity gradients and steeper\ndensity profiles. The number of accreted galaxies, either disrupted or under\ndisruption, that contribute 90% of the accreted halo mass ranges from 1 to 14,\nwith a median of 6.5, and their stellar masses span over three orders of\nmagnitude. The observed halo mass--metallicity relation is well reproduced by\nAuriga and is set by the stellar mass and metallicity of the dominant satellite\ncontributors. This relationship is found not only for the accreted component\nbut also for the total (accreted + in-situ) stellar halo. Our results highlight\nthe potential of observable halo properties to infer the assembly history of\ngalaxies.", "positive": "Testing the universality of the IMF with Bayesian statistics: young\n clusters: The universality of the stellar initial mass function (IMF) is tested using\nBayesian statistics with a sample of eight young Galactic stellar clusters (IC\n348, ONC, NGC 2024, NGC 6611, NGC 2264, $\\rho$ Ophiuchi, Chameleon I, and\nTaurus). We infer the posterior probability distribution function (pPDF) of the\nIMF parameters when the likelihood function is described by a tapered power law\nfunction, a lognormal distribution at low masses coupled to a power law at\nhigher masses, and a multi-component power law function. The inter-cluster\ncomparison of the pPDFs of the IMF parameters for each likelihood function\nshows that these distributions do not overlap within the $1\\sigma$ uncertainty\nlevel. Furthermore, the most probable values of the IMF parameters for most of\nthe clusters deviate substantially from their values for the Galactic field\nstellar IMF. We also quantify the effects of taking into account the\ncompleteness correction as well as the uncertainties on the measured masses.\nThe inclusion of the former affects the inferred pPDFs of the slope of the IMF\nat the low mass end while considering the latter affects the pPDFs of the slope\nof the IMF in the intermediate- to high mass regime. As variations are observed\nin all of the IMF parameters at once and for each of the considered likelihood\nfunctions, even for completeness corrected samples, we argue that the observed\nvariations are real and significant, at least for the sample of eight clusters\nconsidered in this work. The results presented here clearly show that the IMF\nis not universal." }, { "anchor": "Modelling of dust emission of a filament in the Taurus molecular cloud: Dust emission is an important tool in studies of star-forming clouds, as a\ntracer of column density and indirectly via the dust evolution that is\nconnected to the history and physical conditions of the clouds. We examine\nradiative transfer (RT) modelling of dust emission over an extended cloud\nregion, using a filament in the Taurus molecular cloud as an example. We\nexamine how well far-infrared observations can be used to determine both the\ncloud and the dust properties. Using different assumptions of the cloud shape,\nradiation field, and dust properties, we fit RT models to Herschel observations\nof the Taurus filament. Further comparisons are made with measurements of the\nnear-infrared extinction. The models are used to examine the degeneracies\nbetween the different cloud parameters and the dust properties. The results\nshow significant dependence on the assumed cloud structure and the spectral\nshape of the external radiation field. If these are constrained to the most\nlikely values, the observations can be explained only if the dust far-infrared\n(FIR) opacity has increased by a factor of 2-3 relative to the values in\ndiffuse medium. However, a narrow range of FIR wavelengths provides only weak\nevidence of the spatial variations in dust, even in the models covering several\nsquare degrees of a molecular cloud. The analysis of FIR dust emission is\naffected by several sources of uncertainty. Further constraints are therefore\nneeded from observations at shorter wavelengths, especially regarding the\ntrends in dust evolution.", "positive": "Maser emission during post-AGB evolution: This contribution reviews recent observational results concerning\nastronomical masers toward post-AGB objects with a special attention to water\nfountain sources and the prototypical source OH231.8+4.2. These sources\nrepresent a short transition phase in the evolution between circumstellar\nenvelopes around asymptotic giant branch stars and planetary nebulae. The main\nmasing species are considered and key results are summarized." }, { "anchor": "Signatures of AGN induced metal loss in the stellar population: One way the AGN are expected to influence the evolution of their host\ngalaxies is by removing metal content via outflows. In this article we present\nresults that show that AGN can have an effect on the chemical enrichment of\ntheir host galaxies using the fossil record technique on CALIFA galaxies. We\nclassified the chemical enrichment histories of all galaxies in our sample\nregarding whether they show a drop in the value of their metallicity. We find\nthat galaxies currently hosting an AGN are more likely to show this drop in\ntheir metal content compared to the quiescent sample. Once we separate the\nsample by their star-forming status we find that star-forming galaxies are less\nlikely to have a drop in metallicity but have deeper decreases when these\nappear. This behavior could be evidence for the influence of either pristine\ngas inflows or galactic outflows triggered by starbursts, both of which can\nproduce a drop in metallicity.", "positive": "Measuring the Milky Way mass distribution in the presence of the LMC: The ongoing interaction between the Milky Way (MW) and its largest satellite\n- the Large Magellanic Cloud (LMC) - creates a significant perturbation in the\ndistribution and kinematics of distant halo stars, globular clusters and\nsatellite galaxies, and leads to biases in MW mass estimates from these tracer\npopulations. We present a method for compensating these perturbations for any\nchoice of MW potential by computing the past trajectory of LMC and MW and then\nintegrating the orbits of tracer objects back in time until the influence of\nthe LMC is negligible, at which point the equilibrium approximation can be used\nwith any standard dynamical modelling approach. We add this orbit-rewinding\nstep to the mass estimation approach based on simultaneous fitting of the\npotential and the distribution function of tracers, and apply it to two\ndatasets with the latest Gaia EDR3 measurements of 6d phase-space coordinates:\nglobular clusters and satellite galaxies. We find that models with LMC mass in\nthe range (1-2)x10^11 Msun better fit the observed distribution of tracers, and\nmeasure MW mass within 100 kpc to be (0.75+-0.1)x10^12 Msun, while neglecting\nthe LMC perturbation increases it by ~15%." }, { "anchor": "The best of both worlds: Combining LOFAR and Apertif to derive resolved\n radio spectral index images: Supermassive black holes at the centres of galaxies can cycle through periods\nof activity and quiescence. Characterising the duty cycle of active galactic\nnuclei is crucial for understanding the impact of the energy they release on\nthe host galaxy. For radio AGN, this can be done by identifying dying (remnant)\nand restarted radio galaxies from their radio spectral properties. Using the\ncombination of images at 1400 MHz produced by Apertif, the new phased-array\nfeed receiver installed on the Westerbork Synthesis Radio Telescope, and images\nat 150 MHz provided by LOFAR, we have derived resolved spectral index images\n(at a resolution of ~15 arcsec) for all the sources within ~6 deg^2 area of the\nLockman Hole region. We were able to select 15 extended radio sources with\nemission (partly or entirely) characterised by extremely steep spectral indices\n(steeper than 1.2). These objects represent radio sources in the remnant or the\nrestarted phases of their life cycle. Our findings suggest this cycle to be\nrelatively fast. They also show a variety of properties relevant for modelling\nthe evolution of radio galaxies. For example, the restarted activity can occur\nwhile the remnant structure from a previous phase of activity is still visible.\nThis provides constraints on the duration of the 'off' (dying) phase. In\nextended remnants with ultra-steep spectra at low frequencies, the activity\nlikely stopped a few hundred megayears ago, and they correspond to the older\ntail of the age distribution of radio galaxies, in agreement with simulations\nof radio source evolution. We find remnant radio sources with a variety of\nstructures (from double-lobed to amorphous), suggesting different types of\nprogenitors. The present work sets the stage for exploiting low-frequency\nspectral index studies of extended sources by taking advantage of the large\nareas common to the LOFAR and the Apertif surveys.", "positive": "Detailed study of the Bootes field using 300-500 MHz uGMRT observations:\n Source Properties and radio--infrared correlations: The dominant source of radio continuum emissions at low frequencies is\nsynchrotron radiation, which originates from star-forming regions in disk\ngalaxies and from powerful jets produced by active galactic nuclei (AGN). We\nstudied the Bootes field using the upgraded Giant Meterwave Radio Telescope\n(uGMRT) at 400 MHz, achieving a central minimum off-source RMS noise of\n35$\\mu$Jy beam$^{-1}$ and a catalogue of 3782 sources in $\\sim6$ sq. degrees of\nthe sky. The resulting catalogue was compared to other radio frequency\ncatalogues, and the corrected normalised differential source counts were\nderived. We use standard multi-wavelength techniques to classify the sources in\nstar-forming galaxies (SFGs), radio-loud (RL) AGN, and radio-quiet (RQ) AGN\nthat confirm a boost in the SFGs and RQ\\,AGN AGN populations at lower flux\nlevels. For the first time, we investigated the properties of the radio--IR\nrelations at 400\\,MHz in this field. The $L_{\\rm 400 MHz}$--$L_{\\rm TIR}$\nrelations for SFGs were found to show a strong correlation with non-linear\nslope values of $1.10\\pm0.01$, and variation of $q_{\\rm TIR}$ with $z$ is given\nas, $q_{\\rm TIR} = (2.19 \\pm 0.07)\\ (1+z)^{-0.15 \\pm 0.08}$. This indicates\nthat the non-linearity of the radio--IR relations can be attributed to the mild\nvariation of $q_{\\rm TIR}$ values with $z$. The derived relationships exhibit\nsimilar behaviour when applied to LOFAR at 150 MHz and also at 1.4 GHz. This\nemphasises the fact that other parameters like magnetic field evolution with\n$z$ or the number densities of cosmic ray electrons can play a vital role in\nthe mild evolution of $q$ values." }, { "anchor": "The CGM$^2$ Survey: Quenching and the Transformation of the\n Circumgalactic Medium: This study addresses how the incidence rate of strong O VI absorbers in a\ngalaxy's circumgalactic medium (CGM) depends on galaxy mass and, independently,\non the amount of star formation in the galaxy. We use HST/COS absorption\nspectroscopy of quasars to measure O VI absorption within 400 projected kpc and\n300 km s$^{-1}$ of 52 $M_{*}\\sim 10^{10}$ $M_\\odot$ galaxies. The galaxies have\nredshifts $0.12~ $0.72 M_\\odot$) and along the giant branch for\nM_J >~ -2.5. Converting this to a mass function, we find that the high-mass (M\n> $1\\,M_\\odot$) present-day mass function along the main sequence is d n / d M\n= 0.016 $(M/M_\\odot)^{-4.7}$ stars/pc^3/$M_\\odot$. Extrapolating below M =\n$0.72\\,M_\\odot$, we find a total mid-plane stellar density of 0.040+/-0.002\n$M_\\odot$/pc^3. Giants contribute 0.00039+/-0.00001 stars/pc^3 or about\n0.00046+/-0.00005 $M_\\odot$/pc^3. The star-formation rate surface density is\n\\Sigma(t) = 7+/-1 exp(-t/[7+/-1 Gyr]) $M_\\odot$/pc^2/Gyr. Overall, we find that\nGaia DR1's selection biases are manageable and allow a detailed new inventory\nof the solar neighborhood to be made that agrees with and extends previous\nstudies. This bodes well for mapping the Milky Way with the full Gaia data set.", "positive": "A treatment procedure for GMOS/IFU data cubes: application to NGC 2835: We present a set of treatment techniques for GMOS/IFU data cubes, including:\ncorrection of the differential atmospheric refraction; Butterworth spatial\nfiltering, to remove high spatial-frequency noise; instrumental fingerprint\nremoval; Richardson-Lucy deconvolution, to improve the spatial resolution of\nthe observations. A comparison with HST images shows that the treatment\ntechniques preserve the morphology of the spatial structures in the data cubes,\nwithout introducing distortions or ghost features. The treatment procedure\napplied to the data cube of the central region of the late-type galaxy NGC 2835\nallowed the detection of a nuclear emitting region with emission-line ratios\nindicating a probable LINER, although the classifications of Transition Object\nor Seyfert galaxy cannot be discarded. Such a detection was not possible\nwithout the data treatment. This shows that the benefits provided by this\ntreatment procedure are not merely cosmetic, but actually affect the quality of\ndifferent types of analyses, like the determination of the fraction of\ngalaxies, of different morphological types, with a central\nSeyfert/LINER/Transition object emission." }, { "anchor": "Merger histories of brightest group galaxies from MUSE stellar\n kinematics: Using Multi-Unit Spectroscopic Explorer (MUSE) spectroscopy, we analyse the\nstellar kinematics of 18 brightest group early-type (BGEs) galaxies, selected\nfrom the Complete Local-Volume Groups Sample (CLoGS). We analyse the kinematic\nmaps for distinct features, and measure specific stellar angular momentum\nwithin one effective radius ($\\lambda_{e}$). We classify the BGEs as fast\n(10/18) or slow (8/18) rotators, suggesting at least two different evolution\npaths. We quantify the anti-correlation between higher-order kinematic moment\n$h_{3}$ and V/$\\sigma$ (using the $\\xi_{3}$ parameter), and the kinematic\nmisalignment angle between the photometric and kinematic position angles (using\nthe $\\Psi$ parameter), and note clear differences between these parameter\ndistributions of the fast and slow rotating BGEs. We find that all 10 of our\nfast rotators are aligned between the morphological and kinematical axis,\nconsistent with an oblate galaxy shape, whereas the slow rotators are spread\nover all three classes: oblate (1/8), triaxial (4/8), and prolate (3/8). We\nplace the results into context using known radio properties, X-ray properties,\nand observations of molecular gas. We find consistent merger histories inferred\nfrom observations for the fast-rotating BGEs, indicating that they experienced\ngas-rich mergers or interactions, and these are very likely the origin of the\ncold gas. Observational evidence for the slow rotators are consistent with\ngas-poor mergers. For the slow rotators with cold gas, all evidence point to\ncold gas cooling from the intragroup medium.", "positive": "Massive young stellar objects in the N66/NGC346 region of the SMC: We present HK spectra of three sources located in the N66 region of the Small\nMagellanic Cloud. The sources display prominent stellar Br Gamma and extended\nH2 emission, and exhibit infrared excesses at lambda > 2 micron. Based on their\nspectral features, and photometric spectral energy distributions, we suggest\nthat these sources are massive young stellar objects (mYSOs). The findings are\ninterpreted as evidence of on-going high mass star formation in N66." }, { "anchor": "Improving blazar redshift constraints with the edge of the Ly$\u03b1$\n forest: 1ES 1553+113 and implications for observations of the WHIM: Blazars are some of the brightest UV and X-ray sources in the sky and are\nvaluable probes of the elusive warm-hot intergalactic medium (WHIM; $T{\\simeq}\n10^5-10^7$ K). However, many of the brightest blazars$-$called BL Lac objects\nsuch as 1ES1553+113$-$have quasi-featureless spectra and poorly constrained\nredshifts. Here, we significantly improve the precision of indirect redshift\nconstraints for blazars based on the edge of the $\\rm{H\\,I}$ Ly$\\alpha$ forest\nobserved in their UV spectra. We develop a robust technique to constrain the\nredshift of a $z<0.5$ AGN or blazar with a $1\\sigma$ uncertainty of\n${\\approx}0.01$ using only the position of its highest-redshift Ly$\\alpha$\nabsorber with $\\log N_{\\rm{H\\,I}}/{\\rm cm^{-2}} > 12.6$. We use a large sample\nof 192 AGN/QSOs at $0.01\\lesssim z\\lesssim0.45$ that have high-quality COS FUV\nspectra to characterize the intrinsic scatter in the gap between the AGN\nredshift and the edge of their Ly$\\alpha$ forest. We present new COS NUV data\nfor 1ES1553+113 and confirm its redshift of $z=0.433$ using our technique. We\napply our Ly$\\alpha$-forest-based redshift estimation technique to nine\nadditional blazars with archival ${\\it HST}$ UV spectra, most of which are key\ntargets for future X-ray missions. Our inferred redshift constraints improve\nestimates for two BL Lacs (1ES1118+424 and S50716+714) and are consistent with\nprevious estimates for the rest. Our results emphasize the need to obtain\nfurther UV spectra of bright blazars, of which many have uncertain redshifts,\nin order to maximize the scientific value of future X-ray WHIM observations\nthat will improve our understanding of galaxy evolution.", "positive": "Merger-driven infall of metal-poor gas in luminous infrared galaxies: a\n deep dive beneath the mass-metallicity relation: The build up of heavy elements and the stellar mass assembly are fundamental\nprocesses in the formation and evolution of galaxies. Although they have been\nextensively studied through observations and simulations, the key elements that\ngovern these processes, such as gas accretion and outflows, are not fully\nunderstood. This is especially true for luminous and massive galaxies, which\nusually suffer strong feedback in the form of massive outflows, and large-scale\ngas accretion triggered by galaxy interactions. For a sample of 77 luminous\ninfrared (IR) galaxies, we derive chemical abundances using new diagnostics\nbased on nebular IR lines, which peer through the dusty medium of these objects\nand allow us to include the obscured metals in our abundance determinations. In\ncontrast to optical-based studies, our analysis reveals that most luminous IR\ngalaxies remain close to the mass-metallicity relation. Nevertheless, four\ngalaxies with extreme star-formation rates ($> 60$M$_{\\odot }$yr$^{-1}$) in\ntheir late merger stages show heavily depressed metallicities of 12+log(O/H)\n$\\sim 7.7$--$8.1$ along with solar-like N/O ratios, indicative of gas mixing\nprocesses affecting their chemical composition. This evidence suggests the\naction of a massive infall of metal-poor gas in a short phase during the late\nmerger stages, eventually followed by a rapid enrichment. These results\nchallenge the classical gas equilibrium scenario usually applied to\nmain-sequence galaxies, suggesting that the chemical enrichment and\nstellar-mass growth in luminous IR galaxies are regulated by different\nprocesses." }, { "anchor": "Abundance anomalies in metal-poor stars from Population III supernova\n ejecta hydrodynamics: We present a simulation of the long-term evolution of a Population III\nsupernova remnant in a cosmological minihalo. Employing passive Lagrangian\ntracer particles, we investigate how chemical stratification and anisotropy in\nthe explosion can affect the abundances of the first low-mass, metal-enriched\nstars. We find that reverse shock heating can leave the inner mass shells at\nentropies too high to cool, leading to carbon-enhancement in the re-collapsing\ngas. This hydrodynamic selection effect could explain the observed incidence of\ncarbon-enhanced metal-poor (CEMP) stars at low metallicity. We further explore\nhow anisotropic ejecta distributions, recently seen in direct numerical\nsimulations of core-collapse explosions, may translate to abundances in\nmetal-poor stars. We find that some of the observed scatter in the Population\nII abundance ratios can be explained by an incomplete mixing of supernova\nejecta, even in the case of only one contributing enrichment event. We\ndemonstrate that the customary hypothesis of fully-mixed ejecta clearly fails\nif post-explosion hydrodynamics prefers the recycling of some nucleosynthetic\nproducts over others. Furthermore, to fully exploit the stellar-archaeological\nprogram of constraining the Pop III initial mass function from the observed Pop\nII abundances, considering these hydrodynamical transport effects is crucial.\nWe discuss applications to the rich chemical structure of ultra-faint dwarf\nsatellite galaxies, to be probed in unprecedented detail with upcoming\nspectroscopic surveys.", "positive": "A Recent Major Merger Tale for the Closest Giant Elliptical Galaxy\n Centaurus A: We have used hydrodynamical simulations to model the formation of the closest\ngiant elliptical galaxy, Centaurus A. We find that a single major merger event\nwith a mass ratio up to 1.5, and which has happened ~2 Gyr ago, is able to\nreproduce many of its properties, including galaxy kinematics, the inner gas\ndisk, stellar halo ages and metallicities, and numerous faint features observed\nin the halo. The elongated halo shape is mostly made of progenitor residuals\ndeposited by the merger, which also contribute to stellar shells observed in\nthe Centaurus A halo. The current model also reproduces the measured Planetary\nNebulae line of sight velocity and their velocity dispersion. Models with small\nmass ratio and relatively low gas fraction result in a de Vaucouleurs profile\ndistribution, which is consistent with observations and model expectations. A\nrecent merger left imprints in the age distribution that are consistent with\nthe young stellar and Globular Cluster populations (2-4 Gyrs) found within the\nhalo. We conclude that even if not all properties of Centaurus A have been\naccurately reproduced, a recent major merger has likely occurred to form the\nCentaurus A galaxy as we observe it at present day." }, { "anchor": "Bipolar Molecular Outflow from M17: Kinematics of the molecular clouds in the star forming complex M17 is studied\nusing the high-resolution CO-line mapping data at resolution ($20\" \\sim 0.2$\npc) with the Nobeyama 45-m telescope. The northern molecular cloud of M17,\nwhich we call the molecular \"lobe\", is shown to have an elongated shell\nstructure around a top-covered cylindrical cavity. The lobe is expanding at\n$\\sim 5$ \\kms in the minor axis direction, and at $ \\sim 3/\\cos \\ i$ km\ns$^{-1}$ in the major axis direction, where $i$ is the inclination of the major\naxis. The kinetic energy of the expanding motion is on the order of $\\sim\n3\\times 10^{49}$ ergs. We show that the lobe is a backyard structure having the\ncommon origin to the denser molecular \"horn\" flowing out from NGC 6618 toward\nthe south, so that the lobe and horn compose a bipolar outflow. Intensity\ndistributions across the lobe and horn show a double-peak profile typical for a\ncylinder around a cavity. Position-velocity diagrams (PVD) across the lobe and\nhorn exhibit open ring structure with the higher- and/or lower-velocity side(s)\nbeing lacking or faded. This particular PVD behavior can be attributed to\noutflow in a conical cylinder with the flow velocity increasing toward the lobe\nand horn axes.", "positive": "Astro2020 Science White Paper: Spatially Resolved UV Nebular Diagnostics\n in Star-Forming Galaxies: Diagnosing the physical and chemical conditions within star-forming galaxies\n(SFGs) is of paramount importance to understanding key components of galaxy\nformation and evolution: star-formation, gas enrichment, outflows, and\naccretion. Well established optical emission-line diagnostics used to discern\nsuch properties (i.e., metal content, density, strength/shape of ionizing\nradiation) will be observationally inaccessible for the earliest galaxies,\nemphasizing the need for robust, reliable interstellar medium (ISM) diagnostics\nat ultraviolet (UV) wavelengths. Calibrating these UV diagnostics requires a\ncomprehensive comparison of the UV and optical emission lines in nearby SFGs.\nOptical integral field unit (IFU) surveys have revealed the inhomogeneous\nnature of the ISM in SFGs, which leads to non-systematic biases in the\ninterpretation of unresolved sources. Spatial variations are especially\nimportant to consider at UV wavelengths, where the strongest emission features\noriginate from only the highest excitation regions of the nebula and are\nchallenging to distinguish from competing high-ionization sources (e.g.,\nshocks, AGN, etc.). Since surveys collecting large-scale optical integral field\nunit (IFU) spectroscopy are already underway, this white paper calls for an IFU\nor multi-object far-UV (FUV) spectroscopic instrument with high sensitivity,\nhigh spatial resolution, and large field of view (FoV). Given the impact of\nlarge-scale optical IFU surveys over the past decade, this white paper\nemphasizes the scientific need for a comparable foundation of\nspatially-resolved far-UV spectroscopy survey of nearby galaxies that will lay\nthe foundation of diagnostics critical to the interpretation of the distant\nuniverse." }, { "anchor": "Kinematics of Outer Halo Globular Clusters in M31: We present the first kinematic analysis of the far outer halo globular\ncluster (GC) population in the Local Group galaxy M31. Our sample contains 53\nobjects with projected radii of ~20-130 kpc, of which 44 have no previous\nspectroscopic information. GCs with projected radii >30 kpc are found to\nexhibit net rotation around the minor axis of M31, in the same sense as the\ninner GCs, albeit with a smaller amplitude of 79 +/-19 km/s. The\nrotation-corrected velocity dispersion of the full halo GC sample is 106 +/-12\nkm/s, which we observe to decrease with increasing projected radius. We find\ncompelling evidence for kinematic-coherence amongst GCs which project on top of\nhalo substructure, including a clear signature of infall for GCs lying along\nthe North-West stream. Using the tracer mass estimator, we estimate the\ndynamical mass of M31 within 200 kpc to be M_M31 = (1.2-1.5) +/- 0.2 x 10^12\nM_sun. This value is highly dependent on the chosen model and assumptions\nwithin.", "positive": "A Sample of Massive Black Holes in Dwarf Galaxies Detected via [Fe X]\n Coronal Line Emission: Active Galactic Nuclei and/or Tidal Disruption Events: The massive black hole (BH) population in dwarf galaxies ($M_{\\rm BH}\n\\lesssim 10^5~M_\\odot$) can provide strong constraints on the origin of BH\nseeds. However, traditional optical searches for active galactic nuclei (AGNs)\nonly reliably detect high-accretion, relatively high-mass BHs in dwarf galaxies\nwith low amounts of star formation, leaving a large portion of the overall BH\npopulation in dwarf galaxies relatively unexplored. Here, we present a sample\nof 81 dwarf galaxies ($M_\\star \\le 3 \\times 10^9~M_\\odot$) with detectable [Fe\nX]$\\lambda$6374 coronal line emission indicative of accretion onto massive BHs,\nonly two of which were previously identified as optical AGNs. We analyze\noptical spectroscopy from the Sloan Digital Sky Survey and find [Fe\nX]$\\lambda$6374 luminosities in the range $L_{\\rm\n[Fe\\,X]}\\approx10^{36}$-$10^{39}$ erg s$^{-1}$, with a median value of $1.6\n\\times 10^{38}$ erg s$^{-1}$. The [Fe X]$\\lambda$6374 luminosities are\ngenerally much too high to be produced by stellar sources, including luminous\nType IIn supernovae (SNe). Moreover, based on known SNe rates, we expect at\nmost 8 Type IIn SNe in our sample. On the other hand, the [Fe X]$\\lambda$6374\nluminosities are consistent with accretion onto massive BHs from AGNs or tidal\ndisruption events (TDEs). We find additional indicators of BH accretion in some\ncases using other emission line diagnostics, optical variability, X-ray and\nradio emission (or some combination of these). However, many of the galaxies in\nour sample only have evidence for a massive BH based on their [Fe\nX]$\\lambda$6374 luminosities. This work highlights the power of coronal line\nemission to find BHs in dwarf galaxies missed by other selection techniques and\nto probe the BH population in bluer, lower mass dwarf galaxies." }, { "anchor": "Streaming Motions and Kinematic Distances to Molecular Clouds: We present high-resolution smoothed particle hydrodynamics simulations of a\nregion of gas flowing in a spiral arm and identify dense gas clouds to\ninvestigate their kinematics with respect to a Milky Way model. We find that,\non average, the gas in the arms can have a net radial streaming motion of $v_R\n\\approx -9 \\,\\mathrm{km/s}$ and rotate $\\approx 6 \\,\\mathrm{km/s}$ slower than\nthe circular velocity. This translates to average peculiar motions towards the\nGalaxy centre and opposite to Galactic rotation. These results may be sensitive\nto the assumed spiral arm perturbation, which is $\\approx 3\\%$ of the disc\npotential in our model. We compare the actual distance and the kinematic\nestimate and we find that streaming motions introduce systematic offsets of\n$\\approx 1$ kpc. We find that the distance error can be as large as $\\pm 2$ kpc\nand the recovered cloud positions have distributions that can extend\nsignificantly into the inter-arm regions. We conclude that this poses a\ndifficulty in tracing spiral arm structure in molecular cloud surveys.", "positive": "Systematic Survey for [OII], [OIII], and H$\u03b1$ Blobs at $z=0.1-1.5$:\n The Implication for Evolution of Galactic-Scale Outflow: We conduct a systematic search for galaxies at $z=0.1-1.5$ with\n[OII]$\\lambda3727$, [OIII]$\\lambda5007$, or H$\\alpha\\lambda6563$ emission lines\nextended over at least 30 kpc by using deep narrowband and broadband imaging in\nSubaru-XMM Deep Survey (SXDS) field. These extended emission-line galaxies are\ndubbed [OII], [OIII], or H$\\alpha$ blobs. Based on a new selection method that\nsecurely selects extended emission-line galaxies, we find 77 blobs at\n$z=0.40-1.46$ with the isophotal area of emission lines down to\n$1.2\\times10^{-18}$ erg s$^{-1}$ cm$^{-2}$ kpc$^{-2}$. Four of them are\nspectroscopically confirmed to be [OIII] blobs at $z=0.83$. We identify AGN\nactivities in 8 blobs with X-ray and radio data and find that the fraction of\nAGN contribution increases with increasing isophotal area of the extended\nemission. With the Kolmogorov-Smirnov (KS) and Anderson-Darling tests, we\nconfirm that the stellar-mass distributions of H$\\alpha$ and [OII] blobs are\nnot drawn from those of the emitters at the $>90$% confidence level in that\nH$\\alpha$ and [OII] blobs are located at the massive end of the distributions,\nbut cannot reject null hypothesis of being the same distributions in terms of\nthe specific star formation rates. It is suggested that galactic-scale outflows\ntend to be more prominent in more massive star-forming galaxies. Exploiting our\nsample homogeneously selected over the large area, we derive the number\ndensities of blobs at each epoch. The number densities of blobs decrease\ndrastically with redshifts at the rate that is larger than that of the decrease\nof cosmic star formation densities." }, { "anchor": "The Origins of the Circumgalactic Medium in the FIRE Simulations: We use a particle tracking analysis to study the origins of the\ncircumgalactic medium (CGM), separating it into (1) accretion from the\nintergalactic medium (IGM), (2) wind from the central galaxy, and (3) gas\nejected from other galaxies. Our sample consists of 21 FIRE-2 simulations,\nspanning the halo mass range log(Mh/Msun) ~ 10-12 , and we focus on z=0.25 and\nz=2. Owing to strong stellar feedback, only ~L* halos retain a baryon mass\n>~50% of their cosmic budget. Metals are more efficiently retained by halos,\nwith a retention fraction >~50%. Across all masses and redshifts analyzed >~60%\nof the CGM mass originates as IGM accretion (some of which is associated with\ninfalling halos). Overall, the second most important contribution is wind from\nthe central galaxy, though gas ejected or stripped from satellites can\ncontribute a comparable mass in ~L* halos. Gas can persist in the CGM for\nbillions of years, resulting in well-mixed halo gas. Sight lines through the\nCGM are therefore likely to intersect gas of multiple origins. For low-redshift\n~L* halos, cool gas (T<10^4.7 K) is distributed on average preferentially along\nthe galaxy plane, however with strong halo-to-halo variability. The metallicity\nof IGM accretion is systematically lower than the metallicity of winds\n(typically by >~1 dex), although CGM and IGM metallicities depend significantly\non the treatment of subgrid metal diffusion. Our results highlight the multiple\nphysical mechanisms that contribute to the CGM and will inform observational\nefforts to develop a cohesive picture.", "positive": "The Fornax3D project: Assembly histories of lenticular galaxies from a\n combined dynamical and population orbital analysis: Abridged for arXiv: In this work, we apply a powerful new technique in order\nto observationally derive accurate assembly histories through a self-consistent\ncombined stellar dynamical and population galaxy model. We present this\napproach for three edge-on lenticular galaxies from the Fornax3D project -- FCC\n153, FCC 170, and FCC 177 -- in order to infer their mass assembly histories\nindividually and in the context of the Fornax cluster. The method was tested on\nmock data from simulations to quantify its reliability. We find that the\ngalaxies studied here have all been able to form dynamically-cold (intrinsic\nvertical velocity dispersion $\\sigma_z \\lesssim 50\\ {\\rm km}\\ {\\rm s}^{-1}$)\nstellar disks after cluster infall. Moreover, the pre-existing (old) high\nangular momentum components have retained their angular momentum (orbital\ncircularity $\\lambda_z > 0.8$) through to the present day. Comparing the\nderived assembly histories with a comparable galaxy in a low-density\nenvironment -- NGC 3115 -- we find evidence for cluster-driven suppression of\nstellar accretion and merging. We measured the intrinsic stellar\nage--velocity-dispersion relation and find that the shape of the relation is\nconsistent with galaxies in the literature across redshift. There is tentative\nevidence for enhancement in the luminosity-weighted intrinsic vertical velocity\ndispersion due to the cluster environment. But importantly, there is an\nindication that metallicity may be a key driver of this relation. We finally\nspeculate that the cluster environment is responsible for the S0 morphology of\nthese galaxies via the gradual external perturbations, or `harassment',\ngenerated within the cluster." }, { "anchor": "Cold Dust Emission from X-ray AGN in the SCUBA-2 Cosmology Legacy\n Survey: Dependence on Luminosity, Obscuration & AGN Activity: We study the 850um emission in X-ray selected AGN in the 2 sq-deg COSMOS\nfield using new data from the SCUBA-2 Cosmology Legacy Survey. We find 19 850um\nbright X-ray AGN in a high-sensitivity region covering 0.89 sq-deg with flux\ndensities of S850=4-10 mJy. The 19 AGN span the full range in redshift and hard\nX-ray luminosity covered by the sample - 0.71 X-ray AGN - S850=0.71+/-0.08mJy. We explore\ntrends in the stacked 850um flux densities with redshift, finding no evolution\nin the average cold dust emission over the redshift range probed. For Type 1\nAGN, there is no significant correlation between the stacked 850um flux and\nhard X-ray luminosity. However, in Type 2 AGN the stacked submm flux is a\nfactor of 2 higher at high luminosities. When averaging over all X-ray\nluminosities, no significant differences are found in the stacked submm fluxes\nof Type 1 and Type 2 AGN as well as AGN separated on the basis of X-ray\nhardness ratios and optical-to-infrared colours. However, at log10(LX) >44.4,\ndependences in average submm flux on the optical-to-infrared colours become\nmore pronounced. We argue that these high luminosity AGN represent a transition\nfrom a secular to a merger-driven evolutionary phase where the star formation\nrates and accretion luminosities are more tightly coupled. Stacked AGN 850um\nfluxes are compared to the stacked fluxes of a mass-matched sample of K-band\nselected non-AGN galaxies. We find that at 10.55$\nGHz). The simplest explanation would be that no large HI column\n(N(HI)$>10^{17}$ cm$^{-2}$) is present towards the radio `core' and the optical\nAGN. Based on the joint optical and radio analysis of a heterogeneous sample of\n16 quasars ($z_{median}$ = 0.7) and 15 radio galaxies ($z_{median}$ = 0.3) with\nHI 21-cm absorption detection and matched in 1.4 GHz luminosity (L$_{\\rm\n1.4\\,GHz}$), a consistent picture emerges where quasars are primarily tracing\nthe gas in the inner circumnuclear disk and cocoon created by the jet-ISM\ninteraction. These exhibit L$_{1.4\\,\\rm GHz}$ - $\\Delta V_{\\rm null}$\ncorrelation, and frequent mismatch between the radio and optical spectral\nlines. The radio galaxies show no such correlation and likely trace the gas\nfrom the cocoon and the galaxy-wide ISM outside the photoionization cone. The\nanalysis presented here demonstrates the potential of radio spectroscopic\nobservations to reveal the origin of the absorbing gas associated with AGN that\nmay be missed in optical observations.", "positive": "The PDR fronts in M17-SW localized with FIFI-LS onboard SOFIA: To understand star formation rates, studying feedback mechanisms that\nregulate star formation is necessary. The radiation emitted by nascent massive\nstars play a significant role in feedback by photo-dissociating and ionizing\ntheir parental molecular clouds. To gain a detailed picture of the physical\nprocesses, we mapped the photo-dissociation region (PDR) M17-SW in several fine\nstructure and high-J CO lines with FIFI-LS, the far-infrared imaging\nspectrometer aboard SOFIA. An analysis of the CO and [O I]146$\\mu$m line\nintensities, combined with the far infrared intensity, allows us to create a\ndensity and UV intensity map using a one dimensional model. The density map\nreveals a sudden change in the gas density crossing the PDR. The strengths and\nlimits of the model and the locations of the ionization and photo-dissociation\nfront of the edge-on PDR are discussed." }, { "anchor": "Effects of grain growth mechanisms on the extinction curve and the metal\n depletion in the interstellar medium: Dust grains grow their sizes in the interstellar clouds (especially in\nmolecular clouds) by accretion and coagulation. Here we model and test these\nprocesses by examining the consistency with the observed variation of the\nextinction curves in the Milky Way. We find that, if we simply use the\nparameters used in previous studies, the model fails to explain the flattening\nof far-UV extinction curve for large $R_V$ (flatness of optical extinction\ncurve) and the existence of carbon bump even in flat extinction curves. This\ndiscrepancy is resolved by adopting a `tuned' model, in which coagulation of\ncarbonaceous dust is less efficient (by a factor of 2) and that of silicate is\nmore efficient with the coagulation threshold removed. The tuned model is also\nconsistent with the relation between silicon depletion (indicator of accretion)\nand $R_V$ if the duration of accretion and coagulation is >100(n_H/10^3\ncm^{-3})^{-1} Myr, where n_H is the number density of hydrogen nuclei in the\ncloud. We also examine the relations between each of the extinction curve\nfeatures (UV slope, far-UV curvature, and carbon bump strength) and $R_V$. The\ncorrelation between UV slope and $R_V$, which is the strongest among the three\ncorrelations, is well reproduced by the tuned model. For far-UV curvature and\ncarbon bump strength, the observational data are located between the tuned\nmodel and the original model without tuning, implying that the large scatters\nin the observational data can be explained by the sensitive response to the\ncoagulation efficiency. The overall success of the tuned model indicates that\naccretion and coagulation are promising mechanisms of producing the variation\nof extinction curves in the Milky Way, although we do not exclude possibilities\nof other dust-processing mechanisms changing extinction curves.", "positive": "The Evolution of Stellar Velocity Dispersion During Dissipationless\n Galaxy Mergers: Using N-body simulations, we studied the detailed evolution of central\nstellar velocity dispersion, {\\sigma}, during dissipationless binary mergers of\ngalaxies. Stellar velocity dispersion was measured using the common\nmass-weighting method as well as a flux-weighting method designed to simulate\nthe technique used by observers. A toy model for dust attenuation was\nintroduced in order to study the effect of dust attenuation on measurements of\n{\\sigma}. We found that there are three principal stages in the evolution of\n{\\sigma} in such mergers: oscillation, phase mixing, and dynamical equilibrium.\nDuring the oscillation stage, {\\sigma} undergoes damped oscillations of\nincreasing frequency. The oscillation stage is followed by a phase mixing stage\nduring which the amplitude of the variations in {\\sigma} is smaller and more\nchaotic than in the oscillation stage. Upon reaching dynamical equilibrium,\n{\\sigma} assumes a stable value. We used our data regarding the evolution of\n{\\sigma} during mergers to characterize the scatter inherent in making\nmeasurements of {\\sigma} in non-quiescent systems. In particular, we found that\n{\\sigma} does not fall below 70% nor exceed 200% of its final, quiescent value\nduring a merger and that a random measurement of {\\sigma} in such a system is\nmuch more likely to fall near the equilibrium value than near an extremum. Our\ntoy model of dust attenuation suggested that dust can systematically reduce\nobservational measurements of {\\sigma} and increase the scatter in {\\sigma}\nmeasurements." }, { "anchor": "Modeling the Extragalactic Background Light and the Cosmic Star\n Formation History: We present an updated model for the extragalactic background light (EBL) from\nstars and dust, over wavelengths approximately 0.1 to 1000 $\\mu$m. This model\nuses accurate theoretical stellar spectra, and tracks the evolution of star\nformation, stellar mass density, metallicity, and interstellar dust extinction\nand emission in the universe with redshift. Dust emission components are\ntreated self-consistently, with stellar light absorbed by dust reradiated in\nthe infrared as three blackbody components. We fit our model, with free\nparameters associated with star formation rate and dust extinction and\nemission, to a wide variety of data: luminosity density, stellar mass density,\nand dust extinction data from galaxy surveys; and $\\gamma$-ray absorption\noptical depth data from $\\gamma$-ray telescopes. Our results strongly\nconstraint the star formation rate density and dust photon escape fraction of\nthe universe out to redshift $z=10$, about 90% of the history of the universe.\nWe find our model result is, in some cases, below lower limits on the $z=0$ EBL\nintensity, and below some low-$z$ $\\gamma$-ray absorption measurements.", "positive": "From the Fire: A Deeper Look at the Phoenix Stream: We use six years of data from the Dark Energy Survey to perform a detailed\nphotometric characterization of the Phoenix stellar stream, a 15-degree long,\nthin, dynamically cold, low-metallicity stellar system in the southern\nhemisphere. We use natural splines, a non-parametric modeling technique, to\nsimultaneously fit the stream track, width, and linear density. This updated\nstream model allows us to improve measurements of the heliocentric distance\n($17.4 \\pm 0.1\\,{\\rm (stat.)} \\pm 0.8\\,{\\rm (sys.)}$ kpc) and distance gradient\n($-0.009 \\pm 0.006$ kpc deg$^{-1}$) of Phoenix, which corresponds to a small\nchange of $0.13 \\pm 0.09$ kpc in heliocentric distance along the length of the\nstream. We measure linear intensity variations on degree scales, as well as\ndeviations in the stream track on $\\sim 2$-degree scales, suggesting that the\nstream may have been disturbed during its formation and/or evolution. We\nrecover three peaks and one gap in linear intensity along with fluctuations in\nthe stream track. Compared to other thin streams, the Phoenix stream shows more\nfluctuations and, consequently, the study of Phoenix offers a unique\nperspective on gravitational perturbations of stellar streams. We discuss\npossible sources of perturbations to Phoenix including baryonic structures in\nthe Galaxy and dark matter subhalos." }, { "anchor": "X-ray inferred kinematics of the core ICM in Perseus-like clusters:\n insights from the TNG-Cluster simulation: The intracluster medium (ICM) of galaxy clusters encodes the impact of the\nphysical processes that shape these massive halos, including feedback from\ncentral supermassive black holes (SMBHs). In this study we examine the gas\nthermodynamics, kinematics, and the effects of SMBH feedback on the core of\nPerseus-like galaxy clusters with a new simulation suite: TNG-Cluster. We first\nmake a selection of simulated clusters similar to Perseus based on total mass\nand inner ICM properties, i.e. cool-core nature. We identify 30 Perseus-like\nsystems among the 352 TNG-Cluster halos at $z=0$. Many exhibit thermodynamical\nprofiles and X-ray morphologies with disturbed features such as ripples,\nbubbles and shock fronts that are qualitatively similar to X-ray observations\nof Perseus. To study observable gas motions, we generate XRISM mock X-ray\nobservations and conduct a spectral analysis of the synthetic data. In\nagreement with existing Hitomi measurements, TNG-Cluster predicts subsonic gas\nturbulence in the central regions of Perseus-like clusters, with a typical\nline-of-sight velocity dispersion of 200 km/s. This implies that turbulent\npressure contributes $< 10\\%$ to the dominant thermal pressure. In TNG-Cluster,\nsuch low (inferred) values of ICM velocity dispersion coexist with\nhigh-velocity outflows and bulk motions of relatively small amounts of\nsuper-virial hot gas, moving up to thousands of km/s. However, detecting these\noutflows observationally may prove challenging due to their anisotropic nature\nand projection effects. Driven by SMBH feedback, such outflows are responsible\nfor many morphological disturbances in the X-ray maps of cluster cores. They\nalso increase both the inferred, and intrinsic, ICM velocity dispersion. This\neffect is somewhat stronger when velocity dispersion is measured from\nhigher-energy lines.", "positive": "A super-Li rich turnoff star in NGC 6397 - the puzzle persists: This presentation focuses on a recently discovered super-Li rich turnoff star\nin the old, metal poor globular cluster NGC 6397 (Koch et al. 2011, ApJL, 738,\nL29). Its unusually high NLTE lithium abundance of A(7Li) = 4.21, the highest\nLi enhancement found in a Galactic GC dwarf star to date, has defied any\nunambiguous explanation through canonical enrichment channels. Spectra of the\nstar show no convincing evidence for binarity, and measured line strengths and\nchemical element abundance ratios are fully compatible with other turnoff stars\nin this GC, seemingly ruling out mass transfer from an AGB companion as origin\nof the high A(Li). A possible cause is an interaction with a red giant that has\nundergone cool bottom processing." }, { "anchor": "The infrared-radio relation in the local universe: The Square Kilometer Array (SKA) is expected to detect high-redshift galaxies\nwith star formation rates (SFRs) up to two orders of magnitude lower than\nHerschel surveys and will thus boost the ability of radio astronomy to study\nextragalactic sources. The tight infrared-radio correlation offers the\npossibility of using radio emission as a dust-unobscured star formation\ndiagnostic. However, the physics governing the link between radio emission and\nstar formation is poorly understood, and recent studies have pointed to\ndifferences in the exact calibration required when radio is to be used as a\nstar formation tracer. We improve the calibration of the relation of the local\nradio luminosity--SFR and to test whether there are nonlinearities in it. We\nused a sample of Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS)\nsources and investigated their radio luminosity, which was derived using the\nNRAO VLA Sky Survey (NVSS) and Faint Images of the Radio Sky at Twenty-cm\n(FIRST) maps. We stacked the bins of infrared luminosity and SFR and accounted\nfor bins with no detections in the stacked images using survival analysis\nfitting. This approach was tested using Monte Carlo simulations. After removing\nsources from the sample that have excess radio emission, which is indicative of\nnuclear radio activity, we found no deviations from linearity of the mean\nrelations between radio luminosity and either SFR or infrared luminosity. We\nanalyzed the link between radio emission and SFR or infrared luminosity using a\nlocal sample of star-forming galaxies without evidence of nuclear radio\nactivity and found no deviations from linearity, although our data are also\nconsistent with the small nonlinearity reported by some recent analyses. The\nnormalizations of these relations are intermediate between those reported by\nearlier works.", "positive": "Spectroscopic properties of nearby late-type stars, members of stellar\n kinematic groups: Nearby late-type stars are excellent targets to look for young objects in\nstellar associations and moving groups. The study of these groups goes back\nmore than one century ago however, their origin is still misunderstood.\nAlthough their existence have been confirmed by statistical studies of large\nsample of stars, the identification of a group of stars as member of moving\ngroups, is not an easy task, list of members often change with time and most\nmembers have been identified by means of kinematics criteria which is not\nsufficient since many old stars can share the same spatial motion of those\nstars in moving groups. In this contribution we attempt to identify unambiguous\nmoving groups members, among a sample of nearby-late type stars. High\nresolution echelle spectra is used to i) derive accurate radial velocities\nwhich allow us to study the stars' kinematics and make a first selection of\nmoving groups members; and ii) analyze several age-related properties for young\nlate-type stars (i.e., lithium LiI 6707.8 Amstrongs, R'HK index). The different\nage-estimators are compared and the moving group membership of the\nkinematically selected candidates are discussed." }, { "anchor": "The nuclear and integrated far-infrared emission of nearby Seyfert\n galaxies: We present far-infrared (FIR) $70-500\\,\\mu$m imaging observations obtained\nwith Herschel/PACS and SPIRE of 33 nearby (median distance of 30 Mpc) Seyfert\ngalaxies from the Revised Shapley-Ames (RSA) catalogue. We obtain the FIR\nnuclear ($r=1\\,$kpc and $r=2\\,$kpc) and integrated spectral energy\ndistributions (SEDs). We estimate the unresolved nuclear emission at 70 $\\mu$m\nand we fit the nuclear and integrated FIR SEDs with a grey body model. We find\nthat the integrated FIR emission of the RSA Seyferts in our sample is dominated\nby emission from the host galaxy, with dust properties similar to those of\nnormal galaxies (non AGN). We use four criteria to select galaxies whose\nnuclear $70\\,\\mu$m emission has a significant AGN contribution: (1) elevated\n70/160 $\\mu$m flux ratios, (2)spatially resolved, high dust temperature\ngradient, (3) $70\\,\\mu$m excess emission with respect to the fit of the FIR\nSEDs with a grey body, and (4) excess of nuclear SFR obtained from $70\\,\\mu$m\nover SFR from mid-infrared indicators. 16 galaxies (48 per cent of the initial\nsample) satisfy at least one of these conditions, whereas 10 satisfy half or\nmore. After careful examination of these, we select six bona fide candidates\n(18 per cent of the initial sample) and estimate that $\\sim 40-70$ per cent of\ntheir nuclear ($r=1-2\\,$kpc) $70\\,\\mu$m emission is contributed by dust heated\nby the AGN.", "positive": "Resolving the obscuring torus in NGC 1068 with the power of infrared\n interferometry: Revealing the inner funnel of dust: We present new interferometric data obtained with MIDI (MID infrared\nInterferometric instrument) for the Seyfert II galaxy NGC 1068, with an\nextensive coverage of sixteen uv points. These observations resolve the nuclear\nmid-infrared emission from NGC 1068 in unprecedented detail with a maximum\nresolution of 7 mas. For the first time, sufficient uv points have been\nobtained, allowing us to generate an image of the source using maximum entropy\nimage reconstruction. The features of the image are similar to those obtained\nby modelling. We find that the mid-infrared emission can be represented by two\ncomponents, each with a Gaussian brightness distribution. The first, identified\nas the inner funnel of the obscuring torus, is hot (800K), 1.35 parsec long,\nand 0.45 parsec thick in FWHM at a PA=-42 degrees (from north to east). It has\nan absorption profile different than standard interstellar dust and with\nevidence for clumpiness. The second component is 3 by 4 pc in FWHM with T=300K,\nand we identify it with the cooler body of the torus. The compact component is\ntilted by 45 degrees with respect to the radio jet and has similar size and\norientation to the observed water maser distribution. We show how the dust\ndistribution relates to other observables within a few parsecs of the core of\nthe galaxy such as the nuclear masers, the radio jet, and the ionization cone.\nWe compare our findings to a similar study of the Circinus galaxy and other\nrelevant studies. Our findings shed new light on the relation between the\ndifferent parsec-scale components in NGC 1068 and the obscuring torus." }, { "anchor": "Monte Carlo Simulations of Star Clusters - VII. The globular cluster 47\n Tuc: We describe Monte Carlo models for the dynamical evolution of the massive\nglobular cluster 47 Tuc (NGC 104). The code includes treatments of two-body\nrelaxation, most kinds of three- and four-body interactions involving\nprimordial binaries and those formed dynamically, the Galactic tide, and the\ninternal evolution of both single and binary stars. We arrive at a set of\ninitial parameters for the cluster which, after 12Gyr of evolution, gives a\nmodel with a fairly satisfactory match to surface brightness and density\nprofiles, the velocity dispersion profile, the luminosity function in two\nfields, and the acceleration of pulsars. Our models appear to require a\nrelatively steep initial mass function for stars above about turnoff, with an\nindex of about 2.8 (where the Salpeter mass function has an index of 2.35), and\na relatively flat initial mass function (index about 0.4) for the lower main\nsequence. According to the model, the current mass is estimated at 0.9 million\nsolar masses, of which about 34% consists of remnants. We find that primordial\nbinaries are gradually taking over from mass loss by stellar evolution as the\nmain dynamical driver of the core. Despite the high concentration of the\ncluster, core collapse will take at least another 20Gyr.", "positive": "Galactic Center Mini-spiral by ALMA - Possible Origin of the Central\n Cluster: We present continuum images of the \"Galactic Center Mini-spiral\" of 100, 250,\nand 340 GHz bands with the analysis of the Cy.0 data acquired from the Atacama\nLarge Millimeter/submillimeter Array (ALMA) archive. Pretty good UV coverage of\nthe data and the \"self-calibration\" method give us an opportunity to obtain\ndynamic ranges of over 2x10^4 in the resultant maps of the 250 and 340 GHz\nbands. In particular the image of the 340 GHz band has high dynamic ranges\nunprecedented in sub-millimeter wave. The angular resolutions attain to\n1.57\"x1.33\" in the 100 GHz band, 0.63\"x0.53\" in the 250 GHz band, and\n0.44\"x0.38\" in the 340 GHz band, respectively. The continuum images clearly\ndepict the \"Mini-spiral\", which is an ionized gas stream in the vicinity of Sgr\nA*. We found the tight correlation between the dust emission peaks and the\nOB/WR stars in the Northern-arm of the \"Mini-spiral\". The core mass function of\nthe dust core identified by the clumpfind algorithm would obey the flat\npower-law dN/dM=aM^-1.5+/-0.4 on the high-mass side. These support the scenario\nthat the star forming cloud has fallen into the immediate vicinity of Sgr A*\nfor the origin of the Central cluster." }, { "anchor": "The birth of a supermassive black hole binary: We study the dynamical evolution of supermassive black holes, in the late\nstage of galaxy mergers, from kpc to pc scales. In particular, we capture the\nformation of the binary, a necessary step before the final coalescence, and\ntrace back the main processes causing the decay of the orbit. We use\nhydrodynamical simulations of galaxy mergers with different resolutions, from\n$20\\,\\rm pc$ down to $1\\,\\rm pc$, in order to study the effects of the\nresolution on our results, remove numerical effects, and assess that resolving\nthe influence radius of the orbiting black hole is a minimum condition to fully\ncapture the formation of the binary. Our simulations include the relevant\nphysical processes, namely star formation, supernova feedback, accretion onto\nthe black holes and the ensuing feedback. We find that, in these mergers,\ndynamical friction from the smooth stellar component of the nucleus is the main\nprocess that drives black holes from kpc to pc scales. Gas does not play a\ncrucial role and even clumps do not induce scattering or perturb the orbits. We\ncompare the time needed for the formation of the binary to analytical\npredictions and suggest how to apply such analytical formalism to obtain\nestimates of binary formation times in lower resolution simulations.", "positive": "Lyman-$\u03b1$ emission from a WISE-selected optically faint powerful\n radio galaxy M151304.72-252439.7 at $z$ = 3.132: We report the detection of a large ($\\sim90$ kpc) and luminous\n$\\mathrm{Ly\\alpha}$ nebula [$L\\mathrm{_{Ly\\alpha}}$ = $(6.80\\pm0.08)\\times\n10^{44}$] $\\rm{\\,erg\\,s^{-1}}$ around an optically faint (r$>23$ mag) radio\ngalaxy M1513-2524 at $z\\mathrm{_{em}}$=3.132. The double-lobed radio emission\nhas an extent of 184 kpc, but the radio core, i.e., emission associated with\nthe active galactic nucleus (AGN) itself, is barely detected. This object was\nfound as part of our survey to identify high-$z$ quasars based on Wide-field\nInfrared Survey Explorer (WISE) colors. The optical spectrum has revealed\n$\\mathrm{Ly\\alpha}$, NV, CIV and HeII emission lines with a very weak\ncontinuum. Based on long-slit spectroscopy and narrow band imaging centered on\nthe $\\mathrm{Ly\\alpha}$ emission, we identify two spatial components: a\n\"compact component\" with high velocity dispersion ($\\sim\n1500$$\\rm{\\,km\\,s^{-1}}$) seen in all three lines, and an \"extended component\",\nhaving low velocity dispersion (i.e., 700-1000$\\rm{\\,km\\,s^{-1}}$). The\nemission line ratios are consistent with the compact component being in\nphotoionization equilibrium with an AGN. We also detect spatially extended\nassociated $\\mathrm{Ly\\alpha}$ absorption, which is blue-shifted within\n250-400$\\rm{\\,km\\,s^{-1}}$ of the $\\mathrm{Ly\\alpha}$ peak. The probability of\n$\\mathrm{Ly\\alpha}$ absorption detection in such large radio sources is found\nto be low ($\\sim$10%) in the literature. M1513-2524 belongs to the top few\npercent of the population in terms of $\\mathrm{Ly\\alpha}$ and radio\nluminosities. Deep integral field spectroscopy is essential for probing this\ninteresting source and its surroundings in more detail." }, { "anchor": "On measuring the Galactic dark matter halo with hypervelocity stars: Hypervelocity stars (HVSs) travel from the Galactic Centre across the dark\nmatter halo of the Milky Way, where they are observed with velocities in excess\nof the Galactic escape speed. Because of their quasi-radial trajectories, they\nrepresent a unique probe of the still poorly constrained dark matter component\nof the Galactic potential. In this paper, we present a new method to produce\nsuch constraints. Our likelihood is based on the local HVS density obtained by\nback-propagating the observed phase space position and quantifies the ejection\nprobability along the orbit. To showcase our method, we apply it to simulated\nGaia samples of $\\sim200$ stars in three realistic Galactic potentials with\ndark matter components parametrized by spheroidal NFW profiles. We find that\nindividual HVSs exhibit a degeneracy in the scale mass-scale radius plane\n($M_s-r_s$) and are able to measure only the combination $\\alpha = M_s/r_s^2$.\nLikewise, a degeneracy is also present between $\\alpha$ and the spheroidal\naxis-ratio $q$. In the absence of observational errors, we show the whole\nsample can nail down both parameters with {\\it sub-per cent} precision (about\n$1\\%$ and $0.1\\%$ for $\\alpha$ and $q$ respectively) with no systematic bias.\nThis remarkable power to constrain deviations from a symmetric halo is a\nconsequence of the Galactocentric origin of HVSs. To compare our results with\nother probes, we break the degeneracy in the scale parameters and impose a\nmass-concentration relation. The result is a competitive precision on the\nvirial mass $M_{200}$ of about $10\\%$.", "positive": "Triggering Active Galactic Nuclei in Hierarchical Galaxy Formation: Disk\n instability vs. Interactions: Using a semi analytic model for galaxy formation we investigate the effects\nof Black Hole accretion triggered by disk instabilities (DI) in isolated\ngalaxies on the evolution of AGN. Specifically, we took on, developed and\nexpanded the Hopkins & Quataert (2011) model for the mass inflow following disk\nperturbations, and compare the corresponding evolution of the AGN population\nwith that arising in a scenario where galaxy interactions trigger AGN (IT\nmode). We extended and developed the DI model by including different disk\nsurface density profiles, to study the maximal contribution of DI to the\nevolution of the AGN population. We obtained the following results: i) for\nluminosities corresponding to $M_{1450}\\gtrsim -26$ the DI mode can provide the\nBH accretion needed to match the observed AGN luminosity functions up to $z\n\\approx 4.5$; in such a luminosity range and redshift, it can compete with the\nIT scenario as the main driver of cosmological evolution of AGN; ii) The DI\nscenario cannot provide the observed abundance of high-luminosity QSO with\n$M_{1450}\\lesssim -26$ AGN, as well as the abundance of high-redhshift $z\n\\approx 4.5$ QSOs with $M_{1450}\\lesssim -24$, while the IT scenario provides\nan acceptable match up to $z \\approx 6$, as found in our earliest works; iii)\nThe dispersion of the distributions of Eddington ratio for low- and\nintermediate-luminosity AGN (bolometric $L_{AGN}$ = $10^{43}$ - $10^{45}$\nerg/s) is predicted to be much smaller in the DI scenario compared to the IT\nmode; iv) The above conclusions are robust with respect to the explored\nvariants of the Hopkins & Quataert (2011) model. We discuss the physical origin\nof our findings, and how it is possible to pin down the dominant fueling\nmechanism in the low-intermediate luminosity range $M_{1450}\\gtrsim -26$ where\nboth the DI and the IT modes are viable candidates as drivers for the AGN\nevolution." }, { "anchor": "Evolution of the Binary Fraction in Dense Stellar Systems: Using our recently improved Monte Carlo evolution code, we study the\nevolution of the binary fraction in globular clusters. In agreement with\nprevious N-body simulations, we find generally that the hard binary fraction in\nthe core tends to increase with time over a range of initial cluster central\ndensities for initial binary fractions <~ 90%. The dominant processes driving\nthe evolution of the core binary fraction are mass segregation of binaries into\nthe cluster core and preferential destruction of binaries there. On a global\nscale, these effects and the preferential tidal stripping of single stars tend\nto roughly balance, leading to overall cluster binary fractions that are\nroughly constant with time. Our findings suggest that the current hard binary\nfraction near the half-mass radius is a good indicator of the hard primordial\nbinary fraction. However, the relationship between the true binary fraction and\nthe fraction of main-sequence stars in binaries (which is typically what\nobservers measure) is non-linear and rather complicated. We also consider the\nimportance of soft binaries, which not only modify the evolution of the binary\nfraction, but can drastically change the evolution of the cluster as a whole.\nFinally, we describe in some detail the recent addition of single and binary\nstellar evolution to our cluster evolution code.", "positive": "Unidentified infrared bands do not correlate with C/O ratio in planetary\n nebulae: The concrete evidence adduced to support the widely held idea that\nunidentified infrared bands (UIBs) are enhanced in carbon-rich planetary\nnebulae (PNe) is a remarkable UIB 7.7 {\\mu}m versus C/O ratio correlation plot\nfor six PNe, obtained from air-born observations and published in 1986 by M.\nCohen and coworkers. However, the space-born data presented by Cohen & Barlow\nin 2005 undercut this correlation, and I show that the larger dataset they\nprovide disproves a specific link between UIBs and carbon abundance in PNe. It\nalso follows from these data that interstellar UIB carriers cannot originate\nfrom the atmosphere of carbon-rich PNe." }, { "anchor": "Evidence to disfavour dual core system leading to double-peaked narrow\n emission lines: In this manuscript, an interesting method is proposed to test dual core\nsystem for double-peaked narrow emission lines, through precious dual core\nsystem with double-peaked narrow Balmer lines in one system in main galaxy but\nwith single-peaked narrow Balmer lines in the other system in companion galaxy.\nUnder a dual core system, considering narrow Balmer (H$\\alpha$ and H$\\beta$)\nemissions ($f_{e,~\\alpha}$ and $f_{e,~\\beta}$) from companion galaxy but\ncovered by SDSS fiber for the main galaxy and narrow Balmer emissions\n($f_{c,~\\alpha}$ and $f_{c,~\\beta}$) from the companion galaxy covered by SDSS\nfiber for the companion galaxy, the same flux ratios\n$f_{e,~\\alpha}/f_{c,~\\alpha}=f_{e,~\\beta}/f_{c,~\\beta}$ can be expected, due to\ntotally similar physical conditions of each narrow Balmer emission region.\nThen, the precious dual core system in SDSS J2219-0938 is discussed. After\nsubtracting pPXF code determined stellar lights, double-peaked narrow Balmer\nemission lines are confirmed in the main galaxy with confidence level higher\nthan $5\\sigma$, but single-peaked narrow Balmer emission lines in the companion\ngalaxy. Through measured fluxes of emission components,\n$f_{e,~\\alpha}/f_{c,~\\alpha}$ is around 0.82, different from\n$f_{e,~\\beta}/f_{c,~\\beta}\\sim0.52$, to disfavour a dual core system for the\ndouble-peaked narrow Balmer emission lines in SDSS J2219-0938.", "positive": "Luminous, pc-scale CO 6-5 emission in the obscured nucleus of NGC1377: High resolution submm observations are important in probing the morphology,\ncolumn density and dynamics of obscured active galactic nuclei (AGNs). With\nhigh resolution (0.06 x 0.05) ALMA 690 GHz observations we have found bright\n(TB >80 K) and compact (FWHM 10x7 pc) CO 6-5 line emission in the nucleus of\nthe extremely radio-quiet galaxy NGC1377. The integrated CO 6-5 intensity is\naligned with the previously discovered jet/outflow of NGC1377 and is tracing\nthe dense (n>1e4 cm-3), hot gas at the base of the outflow. The velocity\nstructure is complex and shifts across the jet/outflow are discussed in terms\nof jet-rotation or separate, overlapping kinematical components. High velocity\ngas (deltaV +-145 km/s) is detected inside r<2-3 pc and we suggest that it is\nemerging from an inclined rotating disk or torus of position angle PA=140+-20\ndeg with a dynamical mass of approx 3e6 Msun. This mass is consistent with that\nof a supermassive black hole (SMBH), as inferred from the M-sigma relation. The\ngas mass of the proposed disk/torus constitutes <3% of the nuclear dynamical\nmass. In contrast to the intense CO 6-5 line emission, we do not detect dust\ncontinuum with an upper limit of S(690GHz)<2mJy. The corresponding, 5 pc, H2\ncolumn density is estimated to N(H2)<3e23 cm-2, which is inconsistent with a\nCompton Thick (CT) source. We discuss the possibility that CT obscuration may\nbe occuring on small (subparsec) or larger scales. From SED fitting we suggest\nthat half of the IR emission of NGC1377 is nuclear and the rest (mostly the\nfar-infrared (FIR)) is more extended. The extreme radio quietness, and the lack\nof emission from other star formation tracers, raise questions on the origin of\nthe FIR emission. We discuss the possibility that it is arising from the\ndissipation of shocks in the molecular jet/outflow or from irradiation by the\nnuclear source along the poles." }, { "anchor": "Shocked POststarburst Galaxy Survey. III. The Ultraviolet Properties of\n SPOGs: The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify galaxies in\nthe transitional phase between actively star-forming and quiescence with\nnebular lines that are excited from shocks rather than star formation\nprocesses. We explored the ultraviolet (UV) properties of objects with\nnear-ultraviolet (NUV) and far-ultraviolet (FUV) photometry from archival GALEX\ndata; 444 objects were detected in both bands, 365 in only NUV, and 24 in only\nFUV, for a total of 833 observed objects. We compared SPOGs to samples of\nStar-forming galaxies (SFs), Quiescent galaxies (Qs), classical E+A\npost-starburst galaxies, active galactic nuclei (AGN) host galaxies, and\ninteracting galaxies. We found that SPOGs have a larger range in their FUV-NUV\nand NUV-r colors compared to most of the other samples, although all of our\ncomparison samples occupied color space inside of the SPOGs region. Based on\ntheir UV colors, SPOGs are a heterogeneous group, possibly made up of a mixture\nof SFs, Qs, and/or AGN. Using Gaussian mixture models, we are able to recreate\nthe distribution of FUV-NUV colors of SPOGs and E+A galaxies with different\ncombinations of SFs, Qs, and AGN. We find that the UV colors of SPOGs require a\n>60% contribution from SFs, with either Qs or AGN representing the remaining\ncontribution, while UV colors of E+A galaxies required a significantly lower\nfraction of SFs, supporting the idea that SPOGs are at an earlier point in\ntheir transition from quiescent to star-forming than E+A galaxies.", "positive": "Study of central light concentration in nearby galaxies: We propose a novel technique to estimate the masses of super massive black\nholes (SMBHs) residing at the centres of massive galaxies in the nearby\nUniverse using simple photometry. Aperture photometry using SEXTRACTOR is\nemployed to determine the central intensity ratio (CIR) at the optical centre\nof the galaxy image for a sample of 49 nearby galaxies with SMBH mass\nestimations. We find that the CIR of ellipticals and classical bulges is\nstrongly correlated with SMBH masses whereas pseudo bulges and ongoing mergers\nshow significant scatter. Also, the CIR of low luminosity AGNs in the sample\nshows significant connection with the 5 GHz nuclear radio emission suggesting a\nstronger link between the former and the SMBH evolution in these galaxies. In\naddition, it is seen that various structural and dynamical properties of the\nSMBH host galaxies are correlated with the CIR making the latter an important\nparameter in galaxy evolution studies. Finally, we propose the CIR to be an\nefficient and simple tool not only to distinguish classical bulges from pseudo\nbulges but also to estimate the mass of the central SMBH." }, { "anchor": "On the interplay between star formation and feedback in galaxy formation\n simulations: We investigate the star formation-feedback cycle in cosmological galaxy\nformation simulations, focusing on progenitors of Milky Way (MW)-sized\ngalaxies. We find that in order to reproduce key properties of the MW\nprogenitors, such as semi-empirically derived star formation histories and the\nshape of rotation curves, our implementation of star formation and stellar\nfeedback requires 1) a combination of local early momentum feedback via\nradiation pressure and stellar winds and subsequent efficient supernovae\nfeedback, and 2) efficacy of feedback that results in self-regulation of the\nglobal star formation rate on kiloparsec scales. We show that such\nfeedback-driven self-regulation is achieved globally for a local star formation\nefficiency per free fall time of $\\epsilon_{\\rm ff}\\approx 10\\%$. Although this\nvalue is larger that the $\\epsilon_{\\rm ff}\\sim 1\\%$ value usually inferred\nfrom the Kennicutt-Schmidt (KS) relation, we show that it is consistent with\ndirect observational estimates of $\\epsilon_{\\rm ff}$ in molecular clouds.\nMoreover, we show that simulations with local efficiency of $\\epsilon_{\\rm\nff}\\approx 10\\%$ reproduce the global observed KS relation. Such simulations\nalso reproduce the cosmic star formation history of the Milky Way sized\ngalaxies and satisfy a number of other observational constraints. Conversely,\nwe find that simulations that a priori assume an inefficient mode of star\nformation, instead of achieving it via stellar feedback regulation, fail to\nproduce sufficiently vigorous outflows and do not reproduce observations. This\nillustrates the importance of understanding the complex interplay between star\nformation and feedback and the detailed processes that contribute to the\nfeedback-regulated formation of galaxies.", "positive": "The Extremely Luminous Quasar Survey in the Pan-STARRS 1 Footprint\n (PS-ELQS): We present the results of the Extremely Luminous Quasar Survey in the $3\\pi$\nsurvey of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS;\nPS1). This effort applies the successful quasar selection strategy of the\nExtremely Luminous Survey in the Sloan Digital Sky Survey footprint\n($\\sim12,000\\,\\rm{deg}^2$) to a much larger area\n($\\sim\\rm{21486}\\,\\rm{deg}^2$). This spectroscopic survey targets the most\nluminous quasars ($M_{1450}\\le-26.5$; $m_{i}\\le18.5$) at intermediate redshifts\n($z\\ge2.8$). Candidates are selected based on a near-infrared JKW2 color cut\nusing WISE AllWISE and 2MASS photometry to mainly reject stellar contaminants.\nPhotometric redshifts ($z_{\\rm{reg}}$) and star-quasar classifications for each\ncandidate are calculated from near-infrared and optical photometry using the\nsupervised machine learning technique random forests. We select 806 quasar\ncandidates at $z_{\\rm{reg}}\\ge2.8$ from a parent sample of 74318 sources. After\nexclusion of known sources and rejection of candidates with unreliable\nphotometry, we have taken optical identification spectra for 290 of our 334\ngood PS-ELQS candidates. We report the discovery of 190 new $z\\ge2.8$ quasars\nand an additional 28 quasars at lower redshifts. A total of 44 good PS-ELQS\ncandidates remain unobserved. Including all known quasars at $z\\ge2.8$, our\nquasar selection method has a selection efficiency of at least $77\\%$. At lower\ndeclinations $-30\\le\\rm{Decl.}\\le0$ we approximately triple the known\npopulation of extremely luminous quasars. We provide the PS-ELQS quasar catalog\nwith a total of 592 luminous quasars ($m_{i}\\le18.5$, $z\\ge2.8$). This unique\nsample will not only be able to provide constraints on the volume density and\nquasar clustering of extremely luminous quasars, but also offers valuable\ntargets for studies of the intergalactic medium." }, { "anchor": "Science with an ngVLA - The Molecular High-z Universe on Large Scales:\n Low-surface-brightness CO and the strength of the ngVLA Core: The Next-Generation Very Large Array (ngVLA) will revolutionize our\nunderstanding of the Early Universe by tracing the coldest phase of molecular\ngas -the raw ingredient for star formation- in the most distant galaxies and\ngalaxy-clusters. The km-scale core of the ngVLA will be densely packed with\nantennas, making it a prime instrument for imaging low-surface-brightness\nemission from large-scale molecular gas in the high-z circum- and\ninter-galactic medium (CGM/IGM). Recent studies indicate that large amounts of\ncold molecular gas are hiding in the 10s-100 kpc environments of distant\ngalaxies, but that technical limitations on existing telescope arrays have\nprevented us from efficiently detecting these large molecular reservoirs. This\nmay have led to a severely biased view of the molecular Universe. We present\nthe science case for low-surface-brightness CO observations of the Early\nUniverse, and how the core of the ngVLA will reveal the cold molecular Universe\nto limits and at scales not currently detectable by radio telescopes. As such,\nthe ngVLA core will be a powerful instrument for studying the cold baryon cycle\nthat drives the early evolution of galaxies and clusters.", "positive": "Formation of galactic disks through gas-rich mergers: To probe the progenitors of the numerous massive spirals requires to dissect\ndistant galaxy properties through spatially-resolved kinematics, detailed\nmorphologies and photometry from UV to mid-IR. So far IMAGES is the only\nrepresentative sample studied that way. Six billion years ago, 50% of spiral\nprogenitors were experiencing major mergers, evidenced by the combination of\ntheir peculiar kinematics and morphology. IMAGES provides the observational\npoint of the spiral rebuilding scenario, which agrees with predictions from the\nLCDM. It reconciles the disk formation or survival with the observed merger\nrate and allows to reproduce realistic galactic disks with sufficient angular\nmomentum. Several consequences are expected in the Local Universe, because\nancient major mergers had let imprints in galaxy haloes, including the most\nspectacular cases of NGC5907 and M31. An ancient merger in the later galaxy may\nhave left many debris within the Local Group." }, { "anchor": "Non-circular flows in HIghMass galaxies in a test of the late accretion\n hypothesis: We present H-alpha velocity maps for the HIghMass galaxies UGC 7899, UGC\n8475, UGC 9037 and UGC 9334, obtained with the SITELLE Imaging Fourier\nTransform Spectrometer on the Canada-France-Hawaii Telescope, to search for\nkinematic signatures of late gas accretion to explain their large atomic gas\nreservoirs. The maps for UGC 7899, UGC 9037, and UGC 9334 are amenable to disk\nwide radial flow searches with the DiskFit algorithm, and those for UGC 7899\nand UGC 9037 are also amenable to inner-disk kinematic analyses. We find no\nevidence for outer disk radial flows down to Vr ~ 20 km/s in UGC 9037 and UGC\n9334, but hints of such flows in UGC 7899. Conversely, we find clear signatures\nof inner (r ~ 5 kpc) noncircularities in UGC 7899 and UGC 9037 that can be\nmodelled as either bisymmetric (which could be produced by a bar) or radial\nflows. Comparing these models to the structure implied by photometric\ndisk-bulge-bar decompositions, we favour inner radial flows in UGC 7899 and an\ninner bar in UGC 9037. With hints of outer disk radial flows and an outer disk\nwarp, UGC 7899 is the best candidate for late accretion among the galaxies\nexamined, but additional modelling is required to disentangle potential\ndegeneracies between these signatures in H I and H-alpha velocity maps. Our\nsearch provides only weak = constraints on hot-mode accretion models that could\nexplain the unusually high H I content of HIghMass galaxies.", "positive": "Lessons from the Magellanic System and its modeling: The prominent Magellanic Stream that dominates the HI sky provides a\ntantalizing number of observations that potentially constrains the Magellanic\nClouds and the Milky Way outskirts. Here we show that the 'ram-pressure plus\ncollision' model naturally explain these properties, and is able to predict\nsome of the most recent observations made after the model was made. These\ninclude the complexity of the stellar populations in the Magellanic Bridge, for\nwhich kinematics, ages, and distances are well measured, and the North Tidal\nArm, for which the model predicts its formation from the Milky Way tidal\nforces. It appears that this over-constrained model provides a good path to\ninvestigate the Stream properties. This contrasts with tidal models that\nreproduce only half of the Stream's main properties, in particular a tidal tail\ncannot reproduce the observed inter-twisted filaments, and its gas content is\nnot sufficiently massive to provide the large amount of HI and HII gas\nassociated to the Stream. Despite the efforts made to reproduce the large\namounts of gas brought by the Clouds, it seems that no viable solution for the\ntidal model could be foreseen. Since the 'ram-pressure plus collision' model\nhas not succeeded for a Large Magellanic Cloud mass above 2 $\\times10^{10}$\n$M_{\\odot}$, we conjecture that a low mass is required to form the Stream." }, { "anchor": "Radiative AGN feedback on a moving mesh: the impact of the galactic disc\n and dust physics on outflow properties: Feedback from accreting supermassive black holes, active galactic nuclei\n(AGN), is now a cornerstone of galaxy formation models. In this work, we\npresent radiation-hydrodynamic simulations of radiative AGN feedback using the\nnovel Arepo-RT. A central black hole emits radiation at a constant luminosity\nand drives an outflow via radiation pressure on dust grains. Utilising an\nisolated NFW halo we validate our setup in the single and multi-scattering\nregimes, with the simulated shock front propagation in excellent agreement with\nthe expected analytic result. For a spherically symmetric NFW halo, an\nexamination of the simulated outflow properties generated by radiative feedback\ndemonstrates that they are lower than typically observed at a fixed AGN\nluminosity, regardless of the collimation of the radiation. We then explore the\nimpact of a central disc galaxy and the assumed dust model on the outflow\nproperties. The contraction of the halo during the galaxy's formation and\nmodelling the production of dust grains results in a factor $100$ increase in\nthe halo's optical depth. Radiation is then able to couple momentum more\nefficiently to the gas, driving a stronger shock and producing a mass-loaded\n$\\sim10^{3}\\,\\mathrm{M}_{\\odot}\\,\\mathrm{yr}^{-1}$ outflow with a velocity of\n$\\sim2000\\,\\mathrm{km}\\,\\mathrm{s}^{-1}$, in agreement with observations.\nHowever, the inclusion of dust destruction mechanisms, like thermal sputtering,\nleads to the rapid destruction of dust grains within the outflow, reducing its\nproperties below typically observed values. We conclude that radiative AGN\nfeedback can drive outflows, but a thorough numerical and physical treatment is\nrequired to assess its true impact.", "positive": "Accretion Flows or Outflow Cavities? Uncovering the Gas Dynamics around\n Lupus 3-MMS: Understanding how material accretes onto the rotationally supported disk from\nthe surrounding envelope of gas and dust in the youngest protostellar systems\nis important for describing how disks are formed. Magnetohydrodynamic\nsimulations of magnetized, turbulent disk formation usually show spiral-like\nstreams of material (accretion flows) connecting the envelope to the disk.\nHowever, accretion flows in these early stages of protostellar formation still\nremain poorly characterized due to their low intensity and possibly some\nextended structures are disregarded as being part of the outflow cavity. We use\nALMA archival data of a young Class 0 protostar, Lupus 3-MMS, to uncover four\nextended accretion flow-like structures in C$^{18}$O that follow the edges of\nthe outflows. We make various types of position-velocity cuts to compare with\nthe outflows and find the extended structures are not consistent with the\noutflow emission, but rather more consistent with a simple infall model. We\nthen use a dendrogram algorithm to isolate five sub-structures in\nposition-position-velocity space. Four out of the five sub-structures fit well\n($>$95%) with our simple infall model, with specific angular momenta between\n$2.7-6.9\\times10^{-4}\\,$km$\\,$s$^{-1}\\,$pc and mass-infall rates of\n$0.5-1.1\\times10^{-6}\\,M_{\\odot}\\,$yr$^{-1}$. Better characterization of the\nphysical structure in the supposed \"outflow-cavities\" is important to\ndisentangle the true outflow cavities and accretion flows." }, { "anchor": "Gas Content and Kinematics in Clumpy, Turbulent Star-forming Disks: We present molecular gas mass estimates for a sample of 13 local galaxies\nwhose kinematic and star forming properties closely resemble those observed in\n$z\\approx 1.5$ main-sequence galaxies. Plateau de Bure observations of the\nCO[1-0] emission line and Herschel Space Observatory observations of the dust\nemission both suggest molecular gas mass fractions of ~20%. Moreover, dust\nemission modeling finds $T_{dust}<$30K, suggesting a cold dust distribution\ncompared to their high infrared luminosity. The gas mass estimates argue that\n$z\\sim$0.1 DYNAMO galaxies not only share similar kinematic properties with\nhigh-z disks, but they are also similarly rich in molecular material. Pairing\nthe gas mass fractions with existing kinematics reveals a linear relationship\nbetween $f_{gas}$ and $\\sigma$/$v_{c}$, consistent with predictions from\nstability theory of a self-gravitating disk. It thus follows that high gas\nvelocity dispersions are a natural consequence of large gas fractions. We also\nfind that the systems with lowest depletion times ($\\sim$0.5 Gyr) have the\nhighest ratios of $\\sigma$/$v_{c}$ and more pronounced clumps, even at the same\nhigh molecular gas fraction.", "positive": "Universes without the Weak Force: Astrophysical Processes with Stable\n Neutrons: We investigate a class of universes in which the weak interaction is not in\noperation. We consider how astrophysical processes are altered in the absence\nof weak forces, including Big Bang Nucleosynthesis (BBN), galaxy formation,\nmolecular cloud assembly, star formation, and stellar evolution. Without weak\ninteractions, neutrons no longer decay, and the universe emerges from its early\nepochs with a mixture of protons, neutrons, deuterium, and helium. The\nbaryon-to-photon ratio must be smaller than the canonical value in our universe\nto allow free nucleons to survive the BBN epoch without being incorporated into\nheavier nuclei. At later times, the free neutrons readily combine with protons\nto make deuterium in sufficiently dense parts of the interstellar medium, and\nprovide a power source before they are incorporated into stars. Almost all of\nthe neutrons are incorporated into deuterium nuclei before stars are formed. As\na result, stellar evolution proceeds primarily through strong interactions,\nwith deuterium first burning into helium, and then helium fusing into carbon.\nLow-mass deuterium-burning stars can be long-lived, and higher mass stars can\nsynthesize the heavier elements necessary for life. Although somewhat different\nfrom our own, such universes remain potentially habitable." }, { "anchor": "LoCuSS: Pre-processing in galaxy groups falling into massive galaxy\n clusters at z=0.2: We report direct evidence of pre-processing of the galaxies residing in\ngalaxy groups falling into galaxy clusters drawn from the Local Cluster\nSubstructure Survey (LoCuSS). 34 groups have been identified via their X-ray\nemission in the infall regions of 23 massive ($\\rm \\langle M_{200}\\rangle =\n10^{15}\\,M_{\\odot}$) clusters at $0.1595%) of the CO emission stems from spatially-resolved\n(~2-3kpc-diameter) rotating disks, we also detect in both mergers the emission\nfrom high-velocity line wings that extend up to +-500-700km/s, well beyond the\nestimated virial range associated with rotation and turbulence. The kinematic\nmajor axis of the line wing emission is tilted by ~90deg in NGC1614 and by\n~180deg in IRAS17208-0014 relative to their respective rotating disk major\naxes. These results can be explained by the existence of non-coplanar molecular\noutflows in both systems. In stark contrast with NGC1614, where star formation\nalone can drive its molecular outflow, the mass, energy and momentum budget\nrequirements of the molecular outflow in IRAS17208-0014 can be best accounted\nfor by the existence of a so far undetected (hidden) AGN of L_AGN~7x10^11\nL_sun. The geometry of the molecular outflow in IRAS17208-0014 suggests that\nthe outflow is launched by a non-coplanar disk that may be associated with a\nburied AGN in the western nucleus." }, { "anchor": "An Extreme Starburst in Close Proximity to the Central Galaxy of a Rich\n Galaxy Cluster at z=1.7: We have discovered an optically rich galaxy cluster at z=1.7089 with star\nformation occurring in close proximity to the central galaxy. The system,\nSpARCS104922.6+564032.5, was detected within the Spitzer Adaptation of the\nred-sequence Cluster Survey, (SpARCS), and confirmed through Keck-MOSFIRE\nspectroscopy. The rest-frame optical richness of Ngal(500kpc) = 30+/-8 implies\na total halo mass, within 500kpc, of ~3.8+/-1.2 x 10^14 Msun, comparable to\nother clusters at or above this redshift. There is a wealth of ancillary data\navailable, including Canada-France-Hawaii Telescope optical, UKIRT-K,\nSpitzer-IRAC/MIPS, and Herschel-SPIRE. This work adds submillimeter imaging\nwith the SCUBA2 camera on the James Clerk Maxwell Telescope and near-infrared\nimaging with the Hubble Space Telescope (HST). The mid/far-infrared (M/FIR)\ndata detect an Ultra-luminous Infrared Galaxy spatially coincident with the\ncentral galaxy, with LIR = 6.2+/-0.9 x 10^12 Lsun. The detection of polycyclic\naromatic hydrocarbons (PAHs) at z=1.7 in a Spitzer-IRS spectrum of the source\nimplies the FIR luminosity is dominated by star formation (an Active Galactic\nNucleus contribution of 20%) with a rate of ~860+/-30 Msun/yr. The optical\nsource corresponding to the IR emission is likely a chain of of > 10 individual\nclumps arranged as \"beads on a string\" over a linear scale of 66 kpc. Its\nmorphology and proximity to the Brightest Cluster Galaxy imply a gas-rich\ninteraction at the center of the cluster triggered the star formation. This\nsystem indicates that wet mergers may be an important process in forming the\nstellar mass of BCGs at early times.", "positive": "On the robustness of the ammonia thermometer: Ammonia inversion lines are often used as probes of the physical conditions\nin the dense ISM. The excitation temperature between the first two para\nmetastable (rotational) levels is an excellent probe of the gas kinetic\ntemperature. However, the calibration of this ammonia thermometer depends on\nthe accuracy of the collisional rates with H2. Here we present new collisional\nrates for ortho-NH3 and para-NH3 colliding with para-H2 (J=0) and we\ninvestigate the effects of these new rates on the excitation of ammonia.\nScattering calculations employ a new, high accuracy, potential energy surface\ncomputed at the coupled-cluster CCSD(T) level with a basis set extrapolation\nprocedure. Rates are obtained for all transitions involving ammonia levels with\nJ <= 3 and for kinetic temperatures in the range 5-100 K. We find that the\ncalibration curve of the ammonia thermometer -- which relates the observed\nexcitation temperature between the first two para metastable levels to the gas\nkinetic temperature -- does not change significantly when these new rates are\nused. Thus, the calibration of ammonia thermometer appears to be robust.\nEffects of the new rates on the excitation temperature of inversion and\nrotation-inversion transitions are also found to be small." }, { "anchor": "Timing the earliest quenching events with a robust sample of massive\n quiescent galaxies at 2 < z < 5: We present a sample of 151 massive ($M_* > 10^{10}\\mathrm{M_\\odot}$)\nquiescent galaxies at $2 < z < 5$, based on a sophisticated Bayesian spectral\nenergy distribution fitting analysis of the CANDELS UDS and GOODS-South fields.\nOur sample includes a robust sub-sample of 61 objects for which we confidently\nexclude low-redshift and star-forming solutions. We identify 10 robust objects\nat $z>3$, of which 2 are at $z>4$. We report formation redshifts, demonstrating\nthat the oldest objects formed at $z > 6$, however individual ages from our\nphotometric data have significant uncertainties, typically $\\sim0.5$ Gyr. We\ndemonstrate that the UVJ colours of the quiescent population evolve with\nredshift at $z>3$, becoming bluer and more similar to post-starburst galaxies\nat lower redshift. Based upon this we construct a model for the time-evolution\nof quiescent galaxy UVJ colours, concluding that the oldest objects are\nconsistent with forming the bulk of their stellar mass at $z\\sim6-7$ and\nquenching at $z\\sim5$. We report spectroscopic redshifts for two of our objects\nat $z=3.440$ and $3.396$, which exhibit extremely weak Ly$\\alpha$ emission in\nultra-deep VANDELS spectra. We calculate star-formation rates based on these\nline fluxes, finding that these galaxies are consistent with our quiescent\nselection criteria, provided their Ly$\\alpha$ escape fractions are $>3$ and\n$>10$ per cent respectively. We finally report that our highest-redshift robust\nobject exhibits a continuum break at $\\lambda\\sim7000$A in a spectrum from\nVUDS, consistent with our photometric redshift of\n$z_\\mathrm{phot}=4.72^{+0.06}_{-0.04}$. If confirmed as quiescent this object\nwould be the highest-redshift known quiescent galaxy. To obtain stronger\nconstraints on the times of the earliest quenching events, high-SNR\nspectroscopy must be extended to $z\\gtrsim3$ quiescent objects.", "positive": "A magnified view of star formation at redshift 0.9 from two lensed\n galaxies: We present new narrow-band H alpha imaging from the Hubble Space Telescope of\ntwo redshift 0.91 galaxies that have been lensed by foreground galaxy cluster\nAbell 2390. These data probe spatial scales as small as 0.3 kpc, providing a\nmagnified look at the morphology of star formation at an epoch when the global\nstar formation rate was high. However, dust attenuates our spatially resolved\nstar formation rate (SFR) indicators, the H alpha and rest-UV emission, and we\nlack a direct measurement of extinction. Other studies have found that ionized\ngas in galaxies tends to be roughly 50 percent more obscured than stars;\nhowever, given an unextincted measurement of the SFR we can quantify the\nrelative stellar to nebular extinction and the extinction in H{\\alpha}. We\ninfer SFRs from Spitzer and Herschel mid- to far-infrared observations and\ncompare these to integrated H alpha and rest-UV SFRs; this yields stellar to\nnebular extinction ratios consistent with previous studies. We take advantage\nof high spatial resolution and contextualize these results in terms of the\nsource-plane morphologies, comparing the distribution of H alpha to that of the\nrest-frame UV and optical light. In one galaxy, we measure separate SFRs in\nvisually distinct clumps, but can set only a lower limit on the extinction and\nthus the star formation. Consequently, the data are also consistent with there\nbeing an equal amount of extinction along the lines of sight to the ionized gas\nas to the stars. Future observations in the far-infrared could settle this by\nmapping out the dust directly." }, { "anchor": "ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular gas\n reservoirs in high-redshift galaxies: We study the molecular gas properties of high-$z$ galaxies observed in the\nALMA Spectroscopic Survey (ASPECS) that targets a $\\sim1$ arcmin$^2$ region in\nthe Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing\nmolecular gas) in the 3mm and 1mm bands. Of a total of 1302 galaxies in the\nfield, 56 have spectroscopic redshifts and correspondingly well-defined\nphysical properties. Among these, 11 have infrared luminosities\n$L_{\\rm{}IR}>10^{11}$ L$_\\odot$, i.e. a detection in CO emission was expected.\nOut these, 7 are detected at various significance in CO, and 4 are undetected\nin CO emission. In the CO-detected sources, we find CO excitation conditions\nthat are lower than typically found in starburst/SMG/QSO environments. We use\nthe CO luminosities (including limits for non-detections) to derive molecular\ngas masses. We discuss our findings in context of previous molecular gas\nobservations at high redshift (star-formation law, gas depletion times, gas\nfractions): The CO-detected galaxies in the UDF tend to reside on the\nlow-$L_{\\rm{}IR}$ envelope of the scatter in the $L_{\\rm{}IR}-L'_{\\rm{}CO}$\nrelation, but exceptions exist. For the CO-detected sources, we find an average\ndepletion time of $\\sim$ 1 Gyr, with significant scatter. The average\nmolecular-to-stellar mass ratio ($M_{\\rm{}H2}$/$M_*$) is consistent with\nearlier measurements of main sequence galaxies at these redshifts, and again\nshows large variations among sources. In some cases, we also measure dust\ncontinuum emission. On average, the dust-based estimates of the molecular gas\nare a factor $\\sim$2-5$\\times$ smaller than those based on CO. Accounting for\ndetections as well as non-detections, we find large diversity in the molecular\ngas properties of the high-redshift galaxies covered by ASPECS.", "positive": "Protostellar disk accretion in turbulent filaments: Recent observations of protostellar cores suggest that most of the material\nin the protostellar phase is accreted along streamers. Streamers in this\ncontext are defined as velocity coherent funnels of denser material potentially\nconnecting the large scale environment to the small scales of the forming\naccretion disk. Using simulations which simultaneously resolve the driving of\nturbulence on the filament scale as well as the collapse of the core down to\nprotostellar disk scales, we aim to understand the effect of the turbulent\nvelocity field on the formation of overdensities in the accretion flow. We\nperform a three-dimensional numerical study on a core collapse within a\nturbulent filament using the RAMSES code and analyse the properties of\noverdensities in the accretion flow. We find that overdensities are formed\nnaturally by the initial turbulent velocity field inherited from the filament\nand subsequent gravitational collimation. This leads to streams which are not\nreally filamentary but show a sheet-like morphology. Moreover, they have the\nsame radial infall velocities as the low density material. As a main\nconsequence of the turbulent initial condition, the mass accretion onto the\ndisk does not follow the predictions for solid body rotation. Instead, most of\nthe mass is funneled by the overdensities to intermediate disk radii." }, { "anchor": "Confirming new changing--look AGNs discovered through optical\n variability using a random-forest based light curve classifier: Determining the frequency and duration of changing--look (CL) active galactic\nnuclei (AGNs) phenomena, where the optical broad emission lines appear or\ndisappear, is crucial to understand the evolution of the accretion flow around\nsupermassive black holes. We present a strategy to select new CL candidates\nstarting from a spectroscopic type 2 AGNs sample and searching for current type\n1 photometric variability. We use the publicly available Zwicky Transient\nFacility (ZTF) alert stream and the Automatic Learning for the Rapid\nClassification of Events (ALeRCE) light curve classifier to produce a list of\nCL candidates with a highly automated algorithm, resulting in 60 candidates.\nVisual inspection reduced the sample to 30. We performed new spectroscopic\nobservations of six candidates of our clean sample, without further refinement,\nfinding the appearance of clear broad Balmer lines in four of them and\ntentative evidence of type changes in the remaining two, which suggests a\npromising success rate of $\\geq66$ per cent for this CL selection method.", "positive": "Simulating ionization feedback from young massive stars: impact of\n numerical resolution: Modelling galaxy formation in hydrodynamic simulations has increasingly\nadopted various radiative transfer methods to account for photoionization\nfeedback from young massive stars. However, the evolution of HII regions around\nstars begins in dense star-forming clouds and spans large dynamical ranges in\nboth space and time, posing severe challenges for numerical simulations in\nterms of both spatial and temporal resolution that depends strongly on gas\ndensity ($\\propto n^{-1}$). In this work, we perform a series of idealized HII\nregion simulations using the moving-mesh radiation-hydrodynamic code Arepo-RT\nto study the effects of numerical resolution. The simulated results match the\nanalytical solutions and the ionization feedback converges only if the\nStr\\\"omgren sphere is resolved by at least $10$--$100$ resolution elements and\nthe size of each time integration step is smaller than $0.1$ times the\nrecombination timescale. Insufficient spatial resolution leads to reduced\nionization fraction but enhanced ionized gas mass and momentum feedback from\nthe HII regions, as well as degrading the multi-phase interstellar medium into\na diffuse, partially ionized, warm ($\\sim8000$ K) gas. On the other hand,\ninsufficient temporal resolution strongly suppresses the effects of ionizing\nfeedback. This is because longer timesteps are not able to resolve the rapid\nvariation of the thermochemistry properties of the gas cells around massive\nstars, especially when the photon injection and thermochemistry are performed\nwith different cadences. Finally, we provide novel numerical implementations to\novercome the above issues when strict resolution requirements are not\nachievable in practice." }, { "anchor": "Sub-parsec scale imaging of Centaurus A: At a distance of about 3.8 Mpc, the radio galaxy Centaurus A is the closest\nactive galaxy. Therefore it is a key target for studying the innermost regions\nof active galactic nuclei (AGN). VLBI observations conducted within the\nframework of the TANAMI program enable us to study the central region of the\nCen A jet with some of the highest linear resolutions ever achieved in an AGN.\nThis region is the likely origin of the gamma-ray emission recently detected by\nthe Fermi Large Area Telescope (LAT). TANAMI monitors a sample of radio and\ngamma-ray selected extragalactic jets south of -30 degrees declination at 8.4\nGHz and 22.3 GHz with the Australian Long Baseline Array (LBA) and the\ntransoceanic antennas Hartebeesthoek in South Africa, the 6 m Transportable\nIntegrated Geodetic Observatory (TIGO) in Chile and the 9 m German Antarctic\nReceiving Station (GARS) in O'Higgins, Antarctica. The highest angular\nresolution achieved at 8.4 GHz in the case of Cen A is 0.59mas x 0.978mas\n(natural weighting) corresponding to a linear scale of less than 18\nmilliparsec.\n We show images of the first three TANAMI 8.4 GHz observation epochs of the\nsub-parsec scale jet-counterjet system of Cen A. With a simultaneous 22.3 GHz\nobservation in 2008 November, we present a high resolution spectral index map\nof the inner few milliarcseconds of the jet probing the putative emission\nregion of gamma-ray-photons.", "positive": "Unveiling the nature of polar-ring galaxies from deep imaging: General structural properties and low surface brightness tidal features hold\nimportant clues to the formation of galaxies. In this paper, we study a sample\nof polar-ring galaxies (PRGs) based on optical imaging from the Sloan Digital\nSky Survey (SDSS) Stripe82 and other deep surveys. We investigate the deepest\nimages of candidates for PRGs to date. We carry out photometric decomposition\non the host galaxies and associated polar structures that allows us to derive\nthe structural properties of both components. We are able to detect very faint\ntidal structures around most PRGs in our sample. For several galaxies, we can\ndirectly observe the formation of the polar ring due to merging, which is\nmanifested in debris of the victim galaxy and an arc-like polar structure made\nup of its material. In a few cases, we can discern signs of tidal accretion.\nThe results obtained indicate that the gravitational interaction and merging of\ngalaxies are the most plausible mechanisms for the formation of polar-ring\ngalaxies." }, { "anchor": "Chemical abundances as population tracers: Elemental abundance ratios as tracers of stellar populations are discussed\nwith emphasis on F, G, and K stars providing a `fossil' record of the chemical\nevolution of the Galaxy. Most abundance studies have been based on homogeneous\n1D model atmospheres and the assumption of local thermodynamic equilibrium\n(LTE), but recent works have shown that 3D non-LTE corrections can change the\nderived trends of abundance ratios as a function of stellar metallicity very\nsignificantly. However, when comparing stars having similar effective\ntemperatures, surface gravities, and metallicities, 3D non-LTE corrections tend\nto cancel out. When applying such a differential approach to stars in the\nGalactic disk, bulge, and halo, abundance ratios like C/O, Na/Fe, alpha/Fe,\nCu/Fe, Ba/Y, and Eu/Ba point to the existence of multiple discrete populations\nin each of these Galactic components.", "positive": "Reconciling the Diversity and Uniformity of Galactic Rotation Curves\n with Self-Interacting Dark Matter: Galactic rotation curves exhibit diverse behavior in the inner regions, while\nobeying an organizing principle, i.e., they can be approximately described by a\nradial acceleration relation or the Modified Newtonian Dynamics phenomenology.\nWe analyze the rotation curve data from the SPARC sample, and explicitly\ndemonstrate that both the diversity and uniformity are naturally reproduced in\na hierarchical structure formation model with the addition of dark matter\nself-interactions. The required concentrations of the dark matter halos are\nfully consistent with the concentration-mass relation predicted by the Planck\ncosmological model. The inferred stellar mass-to-light ($3.6 \\mu m$) ratios\nscatter around $0.5 M_\\odot/L_\\odot$, as expected from population synthesis\nmodels, leading to a tight radial acceleration relation and baryonic\nTully-Fisher relation. The inferred stellar-halo mass relation is consistent\nwith the expectations from abundance matching. These results indicate that the\ninner dark matter halos of galaxies are thermalized due to the\nself-interactions of dark matter particles." }, { "anchor": "Euclid preparation. XXI. Intermediate-redshift contaminants in the\n search for $z>6$ galaxies within the Euclid Deep Survey: (Abridged) The Euclid mission is expected to discover thousands of z>6\ngalaxies in three Deep Fields, which together will cover a ~40 deg2 area.\nHowever, the limited number of Euclid bands and availability of ancillary data\ncould make the identification of z>6 galaxies challenging. In this work, we\nassess the degree of contamination by intermediate-redshift galaxies (z=1-5.8)\nexpected for z>6 galaxies within the Euclid Deep Survey. This study is based on\n~176,000 real galaxies at z=1-8 in a ~0.7 deg2 area selected from the\nUltraVISTA ultra-deep survey, and ~96,000 mock galaxies with 25.3$\\leq$H<27.0,\nwhich altogether cover the range of magnitudes to be probed in the Euclid Deep\nSurvey. We simulate Euclid and ancillary photometry from the fiducial, 28-band\nphotometry, and fit spectral energy distributions (SEDs) to various\ncombinations of these simulated data. Our study demonstrates that identifying\nz>6 with Euclid data alone will be very effective, with a z>6 recovery of\n91(88)% for bright (faint) galaxies. For the UltraVISTA-like bright sample, the\npercentage of z=1-5.8 contaminants amongst apparent z>6 galaxies as observed\nwith Euclid alone is 18%, which is reduced to 4(13)% by including ultra-deep\nRubin (Spitzer) photometry. Conversely, for the faint mock sample, the\ncontamination fraction with Euclid alone is considerably higher at 39%, and\nminimized to 7% when including ultra-deep Rubin data. For UltraVISTA-like\nbright galaxies, we find that Euclid (I-Y)>2.8 and (Y-J)<1.4 colour criteria\ncan separate contaminants from true z>6 galaxies, although these are applicable\nto only 54% of the contaminants, as many have unconstrained (I-Y) colours. In\nthe most optimistic scenario, these cuts reduce the contamination fraction to\n1% whilst preserving 81% of the fiducial z>6 sample. For the faint mock sample,\ncolour cuts are infeasible.", "positive": "Deep ugrizY Imaging and DEEP2/3 Spectroscopy: A Photometric Redshift\n Testbed for LSST and Public Release of Data from the DEEP3 Galaxy Redshift\n Survey: We present catalogs of calibrated photometry and spectroscopic redshifts in\nthe Extended Groth Strip, intended for studies of photometric redshifts\n(photo-z's). The data includes ugriz photometry from CFHTLS and Y-band\nphotometry from the Subaru Suprime camera, as well as spectroscopic redshifts\nfrom the DEEP2, DEEP3 and 3D-HST surveys. These catalogs incorporate\ncorrections to produce effectively matched-aperture photometry across all\nbands, based upon object size information available in the catalog and Moffat\nprofile point spread function fits. We test this catalog with a simple machine\nlearning-based photometric redshift algorithm based upon Random Forest\nregression, and find that the corrected aperture photometry leads to\nsignificant improvement in photo-z accuracy compared to the original SExtractor\ncatalogs from CFHTLS and Subaru. The deep ugrizY photometry and spectroscopic\nredshifts are well-suited for empirical tests of photometric redshift\nalgorithms for LSST. The resulting catalogs are publicly available. We include\na basic summary of the strategy of the DEEP3 Galaxy Redshift Survey to\naccompany the recent public release of DEEP3 data." }, { "anchor": "The radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 in a galaxy\n merger: The supermassive black holes (SMBHs) of narrow-line Seyfert 1 galaxies\n(NLS1s) are at the lowest end of mass function of active galactic nuclei (AGNs)\nand preferentially reside in late-type host galaxies with pseudobulges, which\nare thought to be formed by internal secular evolution. On the other hand, the\npopulation of radio-loud NLS1s presents a challenge for the relativistic jet\nparadigm that powerful radio jets are exclusively associated with very high\nmass SMBHs in elliptical hosts, which are built-up through galaxy mergers. We\ninvestigated distorted radio structures associated with the nearest gamma-ray\nemitting, radio-loud NLS1 1H 0323+342. This provides supporting evidence for\nthe merger hypothesis based on the past optical/near-infrared observations of\nits host galaxy. The anomalous radio morphology consists of two different\nstructures, the inner curved structure of currently active jet and the outer\nlinear structure of low-brightness relics. Such a coexistence might be\nindicative of the stage of an established black hole binary with precession\nbefore the black holes coalesce in the galaxy merger process. 1H 0323+342 and\nother radio-loud NLS1s under galaxy interactions may be extreme objects on the\nevolutionary path from radio-quiet NLS1s to normal Seyfert galaxies with larger\nSMBHs in classical bulges through mergers and merger-induced jet phases.", "positive": "Time Evolution of Galaxy Scaling Relations in Cosmological Simulations: We predict the evolution of galaxy scaling relationships from cosmological,\nhydrodynamical simulations, that reproduce the scaling relations of present-day\ngalaxies. Although we do not assume co-evolution between galaxies and black\nholes a priori, we are able to reproduce the black hole mass--velocity\ndispersion relation. This relation does not evolve, and black holes actually\ngrow along the relation from significantly less massive seeds than have\npreviously been used. AGN feedback does not very much affect the chemical\nevolution of our galaxies. In our predictions, the stellar mass--metallicity\nrelation does not change its shape, but the metallicity significantly increases\nfrom $z\\sim2$ to $z\\sim1$, while the gas-phase mass-metallicity relation does\nchange shape, having a steeper slope at higher redshifts ($z\\lesssim3$).\nFurthermore, AGN feedback is required to reproduce observations of the most\nmassive galaxies at $z\\lesssim1$, specifically their positions on the star\nformation main sequence and galaxy mass--size relation." }, { "anchor": "From Giant H II regions and H II galaxies to globular clusters and\n compact dwarf ellipticals: Massive starforming regions like Giant HII Regions (GHIIR) and HII Galaxies\n(HIIG) are emission line systems ionized by compact young massive star clusters\n(YMC) with masses ranging from $10^4$M$_\\odot$ to $10^8$M$_\\odot$. We model the\nphotometric and dynamical evolution over a Hubble time of the massive\ngravitationally bound systems that populate the tight relation between absolute\nblue magnitude and velocity dispersion ($M_{B}-\\sigma$) of GHIIR and HIIG and\ncompare the resulting relation with that one of old stellar systems: globular\nclusters, elliptical galaxies, bulges of spirals. After 12~Gyr of evolution\ntheir position on the $\\sigma$ vs. M$_B$ plane coincides -- depending on the\ninitial mass -- either with the globular clusters for systems with initial mass\n$M < 10^6$M$_\\odot$ or with a continuation of the ellipticals, bulges of\nspirals and ultracompact dwarfs for YMC with $M >10^6$M$_\\odot$. The slope\nchange in the $M_{B}-\\sigma$ and $M_B$-size relations at cluster masses around\n$10^6$M$_\\odot$ is due to the larger impact of the dynamical evolution on the\nlower mass clusters. We interpret our result as an indication that the YMC that\nionize GHIIR and HIIG can evolve to form globular clusters and ultra compact\ndwarf ellipticals in about 12 Gyr so that present day globular clusters and\nultra compact dwarf ellipticals may have formed in conditions similar to those\nobserved in today GHIIR and HIIG.", "positive": "Globular clusters in the outer Galactic halo: new HST/ACS imaging of 6\n globular clusters and the Galactic globular cluster age-metallicity relation: Color-magnitude diagrams (CMDs) derived from Hubble Space Telescope (HST)\nAdvanced Camera for Surveys F606W,F814W photometry of 6 globular clusters (GCs)\nare presented. The six GCs form two loose groupings in Galactocentric distance\n(Rgc): IC 4499, NGC 6426, and Ruprecht 106 at ~15-20 kpc and NGC 7006, Palomar\n15, and Pyxis at ~40 kpc. The CMDs allow the ages to be estimated from the main\nsequence turnoff in every case. In addition, the age of Palomar 5 (Rgc ~ 18\nkpc) is estimated using archival HST Wide Field Planetary Camera 2 V,I\nphotometry. The age analysis reveals the following: IC 4499, Ruprecht 106, and\nPyxis are 1-2 Gyr younger than inner halo GCs with similar metallicities; NGC\n7006 and Palomar 5 are marginally younger than their inner halo counterparts;\nNGC 6426 and Palomar 15, the two most metal-poor GCs in the sample, are coeval\nwith all the other metal-poor GCs within the uncertainties. Combined with our\nprevious efforts, the current sample provides strong evidence that the Galactic\nGC age-metallicity relation consists of two distinct branches. One suggests a\nrapid chemical enrichment in the inner Galaxy while the other suggests\nprolonged GC formation in the outer halo. The latter is consistent with the\nouter halo GCs forming in dwarf galaxies and later being accreted by the Milky\nWay." }, { "anchor": "How Black Holes Stop Their Host Galaxy from Growing Without AGN Feedback: Super-massive black holes (SMBHs) with $M_{\\bullet} \\sim 10^9 $ M$_{\\odot}$\nat $z>6$ likely originate from massive seed black holes (BHs). We investigate\nthe consequences of seeding SMBHs with direct collapse BHs (DCBHs)\n($M_{\\bullet}=10^{4-6}\\, \\mathrm{M}_\\odot$) on proto-galactic disc growth. We\nshow that even in the absence of direct feedback effects, the growth of seed\nBHs reduces the development of gravitational instabilities in host galaxy\ndiscs, suppressing star formation and confining stars to a narrow ring in the\ndisc and leading to galaxies at $z \\sim 6$ which lie above the local BH-stellar\nmass relation. The relative magnitude of cosmic and BH accretion rates governs\nthe evolution of the BH-stellar mass relation. For typical DCBH formation\nepochs, $z_{\\rm{i}} \\sim 10$, we find star formation is inhibited in haloes\ngrowing at the average rate predicted by $\\Lambda$CDM which host BHs capable of\nreaching $M_{\\bullet}\\sim 10^9 \\, \\mathrm{M}_{\\odot}$ by $z\\gtrsim6$. Slower\ngrowing BHs cause a delay in the onset of star formation; a $M_{\\bullet} \\sim\n10^6 $ M$_{\\odot}$ seed growing at $0.25$ times the Eddington limit will delay\nstar formation by $\\sim100$ Myr. This delay is reduced by a factor of $\\sim10$\nif the halo growth rate is increased by $\\sim 0.6\\, \\sigma$. Our results\nsuggest that SMBHs seeded by DCBHs and their host galaxies form in separate\nprogenitor haloes. In the absence of subsequent mergers, higher than average\ncosmic accretion or earlier seed formation ($z_{\\rm i} \\sim 20$) are required\nto place the evolving BH on the local BH-stellar mass relation by $z=6$.", "positive": "Inferring a difference in the star-forming properties of lower versus\n higher X-ray luminosity AGNs: We explore the distribution of RMS=SFR/SFR_MS (where SFR_MS is the star\nformation rate of \"Main Sequence\" star-forming galaxies) for AGN hosts at z=1.\nWe split our sample into two bins of X-ray luminosity divided at Lx=2x10^43erg\ns-1 to investigate whether the RMS distribution changes as a function of AGN\npower. Our main results suggest that, when the RMS distribution of AGN hosts is\nmodelled as a log-normal distribution (i.e. the same shape as that of MS\ngalaxies), galaxies hosting more powerful X-ray AGNs (i.e. Lx>2x10^43erg s-1)\ndisplay a narrower RMS distribution that is shifted to higher values compared\nto their lower Lx counterparts. In addition, we find that more powerful X-ray\nAGNs have SFRs that are more consistent with that of MS galaxies compared to\nlower Lx AGNs. Despite this, the mean SFRs (as opposed to RMS) measured from\nthese distributions are consistent with the previously observed flat\nrelationship between SFR and Lx. Our results suggest that the typical\nstar-forming properties of AGN hosts change with Lx , and that more powerful\nAGNs typically reside in more MS-like star-forming galaxies compared to lower\nLx AGNs." }, { "anchor": "The VMC survey - XVII. The proper motion of the Small Magellanic Cloud\n and of the Milky Way globular cluster 47 Tucanae: In this study we use multi-epoch near-infrared observations from the VISTA\nsurvey of the Magellanic Cloud system (VMC) to measure the proper motion of\ndifferent stellar populations in a tile of 1.5 deg sq. in size in the direction\nof the Galactic globular cluster 47 Tuc. We obtain the proper motion of the\ncluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way\nstars. Stars of the three main stellar components are selected from their\nspatial distribution and their distribution in colour-magnitude diagrams. Their\naverage coordinate displacement is computed from the difference between\nmultiple Ks-band observations for stars as faint as Ks=19 mag. Proper motions\nare derived from the slope of the best-fitting line among 10 VMC epochs over a\ntime baseline of ~1 yr. Background galaxies are used to calibrate the absolute\nastrometric reference frame. The resulting absolute proper motion of 47 Tuc is\n(mu_alpha cos(delta), mu_delta)=(+7.26+/-0.03, -1.25+/-0.03) mas/yr. This\nmeasurement refers to about 35000 sources distributed between 10 and 60 arcmin\nfrom the cluster centre. For the SMC we obtain (mu_alpha cos(delta),\nmu_delta)=(+1.16+/-0.07, -0.81+/-0.07) mas/yr from about 5250 red clump and red\ngiant branch stars. The absolute proper motion of the Milky Way population in\nthe line-of-sight (l =305.9, b =-44.9) of this VISTA tile is (mu_alpha\ncos(delta), mu_delta)=(+10.22+/-0.14, -1.27+/-0.12) mas/yr and results from\nabout 4000 sources. Systematic uncertainties associated to the astrometric\nreference system are 0.18 mas/yr. Thanks to the proper motion we detect 47 Tuc\nstars beyond its tidal radius.", "positive": "Merger identification through photometric bands, colours, and their\n errors: Aims. We present the application of a fully connected neural network (NN) for\ngalaxy merger identification using exclusively photometric information. Our\npurpose is not only to test the method's efficiency, but also to understand\nwhat merger properties the NN can learn and what their physical interpretation\nis. Methods. We created a class-balanced training dataset of 5\\,860 galaxies\nsplit into mergers and non-mergers. The galaxy observations came from SDSS DR6\nand were visually identified in Galaxy Zoo. The 2$\\,$930 mergers were selected\nfrom known SDSS mergers and the respective non-mergers were the closest match\nin both redshift and $r$ magnitude. The NN architecture was built by testing a\ndifferent number of layers with different sizes and variations of the dropout\nrate. We compared input spaces constructed using: the five SDSS filters: $u$,\n$g$, $r$, $i$, and $z$; combinations of bands, colours, and their errors; six\nmagnitude types; and variations of input normalization. Results. We find that\nthe fibre magnitude errors contribute the most to the training accuracy.\nStudying the parameters from which they are calculated, we show that the input\nspace built from the sky error background in the five SDSS bands alone leads to\n92.64 $\\pm$ 0.15 \\% training accuracy. We also find that the input\nnormalization, that is to say, how the data are presented to the NN, has a\nsignificant effect on the training performance. Conclusions. We conclude that,\nfrom all the SDSS photometric information, the sky error background is the most\nsensitive to merging processes. This finding is supported by an analysis of its\nfive-band feature space by means of data visualization. Moreover, studying the\nplane of the $g$ and $r$ sky error bands shows that a decision boundary line is\nenough to achieve an accuracy of 91.59\\%." }, { "anchor": "A Comparative Study of Mid-Infrared Star-Formation Rate Tracers and\n Their Metallicity Dependence: We present a comparative study of a set of star-formation rate tracers based\non mid-infrared emission in the 12.81$\\mu$m [Ne II] line, the 15.56$\\mu$m [Ne\nIII] line, and emission features from polycyclic aromatic hydrocarbons (PAHs)\nbetween 5.2 and 14.7$\\mu$m. We calibrate our tracers with the thermal component\nof the radio continuum emission at 33 GHz from 33 extranuclear star-forming\nregions observed in nearby galaxies. Correlations between mid-IR emission\nfeatures and thermal 33 GHz star-formation rates (SFR) show significant\nmetallicity-dependent scatter and offsets. We find similar\nmetallicity-dependent trends in commonly used SFR tracers such as H$\\alpha$ and\n24$\\mu$m. As seen in previous studies, PAH emission alone is a poor SFR tracer\ndue to a strong metallicity dependence: lower metallicity regions show\ndecreased PAH emission relative to their SFR compared to higher metallicity\nregions. We construct combinations of PAH bands, neon emission lines, and their\nrespective ratios to minimize metallicity trends. The calibrations that most\naccurately trace SFR with minimal metallicity dependence involve the sum of the\nintegrated intensities of the 12.81$\\mu$m [Ne II] line and the 15.56$\\mu$m [Ne\nIII] line combined with any major PAH feature normalized by dust continuum\nemission. This mid-IR calibration is a useful tool for measuring SFR as it is\nminimally sensitive to variations in metallicity and it is composed of bright,\nubiquitous emission features. The Mid-Infrared Instrument (MIRI) on the James\nWebb Space Telescope will detect these features from galaxies as far as\nredshift z$\\sim$1. We also investigate the behavior of the PAH band ratios and\nfind that subtracting the local background surrounding a star-forming region\ndecreases the ratio of PAH 11.3$\\mu$m to 7.7$\\mu$m emission. This implies PAHs\nare more ionized in star-forming regions relative to their surroundings.", "positive": "A comparison of cosmological filaments catalogues: In this work we compare three catalogues of cosmological filaments identified\nin the Sloan Digital Sky Survey by means of different algorithms by Tempel et\nal., Pereyra et al., and Mart\\'inez et al. We analyse how different\nidentification techniques determine differences in the filament statistical\nproperties: length, elongation, redshift distribution, and abundance. We find\nthat the statistical properties of the filaments strongly depend on the\nidentification algorithm. We use a volume limited sample of galaxies to\ncharacterise other properties of filaments such as: galaxy overdensity,\nluminosity function of galaxies, mean galaxy luminosity, filament luminosity,\nand the overdensity profile of galaxies around filaments. In general, we find\nthat these properties primarily depended on filament length. Shorter filaments\nhave larger overdensities, are more populated by red galaxies, and have better\ndefined galaxy overdensity profiles, than longer filaments. Concluding that\ngalaxies belonging to filaments have characteristic signatures depending on the\nidentification algorithm used." }, { "anchor": "The Local Bubble is a Local Chimney: A New Model from 3D Dust Mapping: Leveraging a high-resolution 3D dust map of the solar neighborhood from\nEdenhofer et al. (2023), we derive a new 3D model for the dust-traced surface\nof the Local Bubble, the supernova-driven cavity surrounding the Sun. We find\nthat the surface of the Local Bubble is highly irregular in shape, with its\npeak extinction surface falling at an average distance of 170 pc from the Sun\n(spanning 70-600+ pc) with a typical thickness of 35 pc and a total dust-traced\nmass of $(6.0 \\pm 0.7) \\times 10^5 \\ \\rm{M}_{\\odot}$. The Local Bubble displays\nan extension in the Galactic Northern hemisphere that is morphologically\nconsistent with representing a \"Local Chimney.\" We argue this chimney was\nlikely created by the \"bursting\" of this supernova-driven superbubble, leading\nto the funneling of interstellar medium ejecta into the lower Galactic halo. We\nfind that many well-known dust features and molecular clouds fall on the\nsurface of the Local Bubble and that several tunnels to other adjacent cavities\nin the interstellar medium may be present. Our new, parsec-resolution view of\nthe Local Bubble may be used to inform future analysis of the evolution of\nnearby gas and young stars, the investigation of direct links between the solar\nneighborhood and the Milky Way's lower halo, and numerous other applications.", "positive": "Spectral Classification and Ionized Gas Outflows in $z\\sim2$\n WISE-Selected Hot Dust-Obscured Galaxies: We present VLT/XSHOOTER rest-frame UV-optical spectra of 10 Hot Dust-Obscured\nGalaxies (Hot DOGs) at $z\\sim2$ to investigate AGN diagnostics and to assess\nthe presence and effect of ionized gas outflows. Most Hot DOGs in this sample\nare narrow-line dominated AGN (type 1.8 or higher), and have higher Balmer\ndecrements than typical type 2 quasars. Almost all (8/9) sources show evidence\nfor ionized gas outflows in the form of broad and blueshifted [O III] profiles,\nand some sources have such profiles in H$\\alpha$ (5/7) or [O II] (3/6).\nCombined with the literature, these results support additional sources of\nobscuration beyond the simple torus invoked by AGN unification models. Outflow\nrates derived from the broad [O III] line ($\\rm\n\\gtrsim10^{3}\\,M_{\\odot}\\,yr^{-1}$) are greater than the black hole accretion\nand star formation rates, with feedback efficiencies ($\\sim0.1-1\\%$) consistent\nwith negative feedback to the host galaxy's star formation in merger-driven\nquasar activity scenarios. We find the broad emission lines in luminous,\nobscured quasars are often better explained by outflows within the narrow line\nregion, and caution that black hole mass estimates for such sources in the\nliterature may have substantial uncertainty. Regardless, we find lower bounds\non the Eddington ratio for Hot DOGs near unity." }, { "anchor": "Project Icarus: Astronomical Considerations Relating to the Choice of\n Target Star: In this paper we outline the considerations required in order to select a\ntarget star system for the Icarus interstellar mission. It is considered that\nthe maximum likely range for the Icarus vehicle will be 15 light-years, and a\nlist is provided of all known stars within this distance range. As the\nscientific objectives of Icarus are weighted towards planetary science and\nastrobiology, a final choice of target star(s) cannot be made until we have a\nclearer understanding of the prevalence of planetary systems within 15\nlight-years of the Sun, and we summarize what is currently known regarding\nplanetary systems within this volume. We stress that by the time an\ninterstellar mission such as Icarus is actually undertaken, astronomical\nobservations from the solar system will have provided this information.\nFinally, given the high proportion of multiple star systems within 15\nlight-years (including the closest of all stars to the Sun in the {\\alpha}\nCentauri system), we stress that a flexible mission architecture, able to visit\nstars and accompanying planets within multiple systems, is desirable. This\npaper is a submission of the Project Icarus Study Group.", "positive": "Abundance Patterns in the Interstellar Medium of Early-type Galaxies\n Observed with Suzaku: We have analyzed 17 early-type galaxies, 13 ellipticals and 4 S0's, observed\nwith Suzaku, and investigated metal abundances (O, Mg, Si, and Fe) and\nabundance ratios (O/Fe, Mg/Fe, and Si/Fe) in the interstellar medium (ISM). The\nemission from each on-source region, which is 4 times effective radius, r_e, is\nreproduced with one- or two- temperature thermal plasma models as well as a\nmulti-temperature model, using APEC plasma code v2.0.1. The multi-temperature\nmodel gave almost the same abundances and abundance ratios with the 1T or 2T\nmodels. The weighted averages of the O, Mg, Si, and Fe abundances of all the\nsample galaxies derived from the multi-temperature model fits are 0.83+-0.04,\n0.93+-0.03, 0.80+-0.02, and 0.80+-0.02 solar, respectively, in solar units\naccording to the solar abundance table by Lodders (2003). These abundances show\nno significant dependence on the morphology and environment. The systematic\ndifferences in the derived metal abundances between the version 2.0.1 and 1.3.1\nof APEC plasma codes were investigated. The derived O and Mg abundances in the\nISM agree with the stellar metallicity within a aperture with a radius of one\nr_e derived from optical spectroscopy. From these results, we discuss the past\nand present SN Ia rates and star formation histories in early-type galaxies." }, { "anchor": "An ensemble study of turbulence in extended QSO nebulae at\n $z\\approx0.5$--1: Turbulent motions in the circumgalactic medium (CGM) play a critical role in\nregulating the evolution of galaxies, yet their detailed characterization\nremains elusive. Using two-dimensional velocity maps constructed from\nspatially-extended [OII] and [OIII] emission, Chen et al. (2023b) measured the\nvelocity structure functions (VSFs) of four quasar nebulae at\n$z\\approx\\!0.5$--1.1. One of these exhibits a spectacular Kolmogorov relation.\nHere we carry out an ensemble study using an expanded sample incorporating four\nnew nebulae from three additional QSO fields. The VSFs measured for all eight\nnebulae are best explained by subsonic turbulence revealed by the line-emitting\ngas, which in turn strongly suggests that the cool gas ($T\\!\\sim\\!10^4$ K) is\ndynamically coupled to the hot ambient medium. Previous work demonstrates that\nthe largest nebulae in our sample reside in group environments with clear signs\nof tidal interactions, suggesting that environmental effects are vital in\nseeding and enhancing turbulence within the gaseous halos, ultimately promoting\nthe formation of the extended nebulae. No discernible differences are observed\nin the VSF properties between radio-loud and radio-quiet QSO fields. We\nestimate the turbulent heating rate per unit volume, $Q_{\\rm turb}$, in the QSO\nnebulae to be $\\sim 10^{-26}$--$10^{-22}$ erg cm$^{-3}$ s$^{-1}$ for the cool\nphase and $\\sim 10^{-28}$--$10^{-25}$ erg cm$^{-3}$ s$^{-1}$ for the hot phase.\nThis range aligns with measurements in the intracluster medium and star-forming\nmolecular clouds but is $\\sim10^3$ times higher than the $Q_{\\rm turb}$\nobserved inside cool gas clumps on scales $\\lesssim1$ kpc using absorption-line\ntechniques. We discuss the prospect of bridging the gap between emission and\nabsorption studies by pushing the emission-based VSF measurements to below\n$\\approx\\!10$ kpc.", "positive": "Searching for the sources of excess extragalactic dispersion of FRBs: The FLIMFLAM survey is collecting spectroscopic data of field galaxies near\nfast radio burst (FRB) sightlines to constrain key parameters describing the\ndistribution of matter in the Universe. In this work, we leverage the survey\ndata to determine the source of the excess extragalactic dispersion measure\n(DM), compared to the Macquart relation estimate of four FRBs: FRB20190714A,\nFRB20200430A, FRB20200906A, and FRB20210117A. By modeling the gas distribution\naround the foreground galaxy halos and galaxy groups of the sightlines, we\nestimate $\\rm DM_{halos}$, their contribution to the FRB dispersion measures.\nThe FRB20190714A sightline shows a clear excess of foreground halos which\ncontribute roughly 2/3$^{rd}$ of the observed excess DM, thus implying a\nbaryon-dense sightline. FRB20200906A shows a smaller but non-negligible\nforeground halo contribution, and further analysis of the IGM is necessary to\nascertain the true cosmic contribution to its DM. RB20200430A and FRB20210117A\nshow negligible foreground contributions, implying a large host galaxy excess\nand/or progenitor environment excess." }, { "anchor": "Near-Infrared Variability Study of the Central 2.3 arcmin x 2.3 arcmin\n of the Galactic Centre I. Catalog of Variable Sources: We used four-year baseline HST/WFC3 IR observations of the Galactic Centre in\nthe F153M band (1.53 micron) to identify variable stars in the central\n~2.3'x2.3' field. We classified 3845 long-term (periods from months to years)\nand 76 short-term (periods of a few days or less) variables among a total\nsample of 33070 stars. For 36 of the latter ones, we also derived their periods\n(<3 days). Our catalog not only confirms bright long period variables and\nmassive eclipsing binaries identified in previous works, but also contains many\nnewly recognized dim variable stars. For example, we found \\delta Scuti and RR\nLyrae stars towards the Galactic Centre for the first time, as well as one BL\nHer star (period < 1.3 d). We cross-correlated our catalog with previous\nspectroscopic studies and found that 319 variables have well-defined stellar\ntypes, such as Wolf-Rayet, OB main sequence, supergiants and asymptotic giant\nbranch stars. We used colours and magnitudes to infer the probable variable\ntypes for those stars without accurately measured periods or spectroscopic\ninformation. We conclude that the majority of unclassified variables could\npotentially be eclipsing/ellipsoidal binaries and Type II Cepheids. Our source\ncatalog will be valuable for future studies aimed at constraining the distance,\nstar formation history and massive binary fraction of the Milky Way nuclear\nstar cluster.", "positive": "Studies of the distinct regions due to CO selective dissociation in the\n Aquila molecular cloud: Aims. We investigate the role of selective dissociation in the process of\nstar formation by comparing the physical parameters of protostellar-prestellar\ncores and the distinct regions with the CO isotope distributions in\nphotodissociation regions. We seek to understand whether there is a better\nconnection between the evolutionary age of star forming regions and the effect\nof selective dissociation\n Methods. Wide-field observations of the $\\rm ^{12}CO$, $\\rm ^{13}CO$, and\n$\\rm C^{18}O$ ( J = 1 - 0) emission lines are used to study the ongoing star\nformation activity in the Aquila molecular region, and the 70 $\\mu$m and 250\n$\\mu$m data are used to describe the heating of the surrounding material and as\nan indicator of the evolutionary age of the core.\n Results. The protostellar-prestellar cores are found at locations with the\nhighest $\\rm C^{18}O$ column densities and their increasing evolutionary age\nwould relate to an increasing 70$\\mu$m/250$\\mu$m emission ratio at their\nlocation. An evolutionary age of the cores may also follow from the $\\rm\n^{13}CO$ versus $\\rm C^{18}O$ abundance ratio, which decreases with increasing\n$\\rm C^{18}O$ column densities. The original mass has been estimated for nine\nrepresentative star formation regions and the original mass of the region\ncorrelated well with the integrated 70 $\\mu$m flux density. Similarly, the $\nX_{\\rm ^{13}CO}$/$X_{\\rm C^{18}O}$ implying the dissociation rate for these\nregions correlates with the 70$\\mu$m/250$\\mu$m flux density ratio and reflects\nthe evolutionary age of the star formation activity." }, { "anchor": "Morphology of star-forming clumps in ram-pressure stripped galaxies as\n seen by HST: We characterize the morphological properties of a statistically relevant\nsample of H$\\alpha$ and UV young star-forming clumps and optical complexes,\nobserved with the \\textit{Hubble Space Telescope} in six galaxies of the GASP\nsample undergoing ram-pressure stripping. The catalogs comprise 2406 (323 in\nthe tails) H$\\alpha$ clumps, 3750 (899) UV clumps and 424 tail optical\ncomplexes. About 15-20\\% of the clumps and 50\\% of the complexes are resolved\nin size. We find that more than half of the complexes contain no H$\\alpha$\nclumps, while most of them contain at least one UV clump. The clump number and\nsize increase with the complex size, while the median complex filling factor is\nlarger for UV clumps ($0.27$) than for H$\\alpha$ clumps ($0.10$) and does not\ncorrelate with almost any morphological property. This suggests that the clumps\nnumber and size grow with the complex keeping the filling factor constant. When\nstudying the position of the clumps inside their complexes, H$\\alpha$ clumps,\nand UV clumps to a lesser extent, show a displacement from the complex center\nof $0.1-1$ kpc and, in $\\sim 60$\\% of the cases, they are displaced away from\nthe galactic disk. This is in accordance with the fireball configuration,\nalready observed in the tails of stripped galaxies. Finally, the filling factor\nand the clump radius increase with the distance from the galactic disk,\nsuggesting that the reciprocal displacement of the different stellar\ngenerations increases as a consequence of the velocity gradient caused by ram\npressure.", "positive": "Vorticity from irrotationally forced flow: In the interstellar medium the turbulence is believed to be forced mostly\nthrough supernova explosions. In a first approximation these flows can be\nwritten as a gradient of a potential being thus devoid of vorticity. There are\nseveral mechanisms that could lead to vorticity generation, like viscosity and\nbaroclinic terms, rotation, shear and magnetic fields, but it is not clear how\neffective they are, neither is it clear whether the vorticity is essential in\ndetermining the turbulent diffusion acting in the ISM. Here we present a study\nof the role of rotation, shear and baroclinicity in the generation of vorticity\nin the ISM." }, { "anchor": "The VMC survey XXX. Stellar proper motions in the central parts of the\n Small Magellanic Cloud: We present the first spatially resolved map of stellar proper motions within\nthe central ($\\sim$3.1 $\\times$ 2.4 kpc) regions of the Small Magellanic Cloud\n(SMC). The data used for this study encompasses four tiles from the ongoing\nnear-infrared VISTA survey of the Magellanic Clouds system and covers a total\ncontiguous area on the sky of $\\sim$6.81 deg$^2$. Proper motions have been\ncalculated independently in two dimensions from the spatial offsets in the\n$K_s$ filter over time baselines between 22 and 27 months. The reflex motions\nof $\\sim$33~000 background galaxies are used to calibrate the stellar motions\nto an absolute scale. The resulting catalog is composed of more than 690 000\nstars which have been selected based on their position in the $(J-K_s, K_s)$\ncolor-magnitude diagram. For the median absolute proper motion of the SMC, we\nfind ($\\mu_{\\alpha}\\mathrm{cos}(\\delta)$, $\\mu_{\\delta}$) = (1.087 $\\pm$ 0.192\n(sys.) $\\pm$ 0.003 (stat.), $-$1.187 $\\pm$ 0.008 (sys.) $\\pm$ 0.003 (stat.))\nmas yr$^{-1}$, consistent with previous studies. Mapping the proper motions as\na function of position within the SMC reveals a non uniform velocity pattern\nindicative of a tidal feature behind the main body of the SMC and a flow of\nstars in the South-East moving predominantly along the line-of-sight.", "positive": "AGN impact on the molecular gas in galactic centers as probed by CO\n lines: We present a detailed analysis of the X-ray, infrared, and carbon monoxide\n(CO) emission for a sample of 35 local ($z \\leq 0.15$), active ($L_X \\geq\n10^{42}$ erg s$^{-1}$) galaxies. Our goal is to infer the contribution of\nfar-ultraviolet (FUV) radiation from star formation (SF), and X-ray radiation\nfrom the active galactic nuclei (AGN), respectively producing photodissociation\nregions (PDRs) and X-ray dominated regions (XDRs), to the molecular gas\nheating. To this aim, we exploit the CO spectral line energy distribution (CO\nSLED) as traced by Herschel, complemented with data from single-dish telescopes\nfor the low-J lines, and high-resolution ALMA images of the mid-J CO emitting\nregion. By comparing our results to the Schmidt-Kennicutt relation, we find no\nevidence for AGN influence on the cold and low-density gas on kpc-scales. On\nnuclear (r = 250 pc) scales, we find weak correlations between the CO line\nratios and either the FUV or X-ray fluxes: this may indicate that neither SF\nnor AGN radiation dominates the gas excitation, at least at r = 250 pc. From a\ncomparison of the CO line ratios with PDR and XDR models, we find that PDRs can\nreproduce observations only in presence of extremely high gas densities ($n >\n10^5$ cm$^{-3}$). In the XDR case, instead, the models suggest moderate\ndensities ($n \\approx 10^{2-4}$ cm$^{-3}$). We conclude that a mix of the two\nmechanisms (PDR for the mid-J, XDR or possibly shocks for the high-J) is\nnecessary to explain the observed CO excitation in active galaxies." }, { "anchor": "The HMXB Luminosity Functions of Dwarf Galaxies: Drawing from the Chandra archive and using a carefully selected set of nearby\ndwarf galaxies, we present a calibrated high-mass X-ray binary (HMXB)\nluminosity function in the low-mass galaxy regime and search for an already\nhinted at dependence on metallicity. Our study introduces a new sample of local\ndwarf galaxies (D < 12.5 Mpc and M* < 5 x 10^9 M_sun), expanding the specific\nstar-formation rates (sSFR) and gas-phase metallicities probed in previous\ninvestigations. Our analysis of the observed X-ray luminosity function\nindicates a shallower power-law slope for the dwarf galaxy HMXB population. In\nour study, we focus on dwarf galaxies that are more representative in terms of\nsSFR compared to prior work. In this regime, the HMXB luminosity function\nexhibits significant stochastic sampling at high luminosities. This likely\naccounts for the pronounced scatter observed in the galaxy-integrated HMXB\npopulation's Lx/SFR versus metallicity for our galaxy sample. Our calibration\nis necessary to understand the AGN content of low mass galaxies identified in\ncurrent and future X-ray survey fields and has implications for binary\npopulation synthesis models, as well as X-ray driven cosmic heating in the\nearly universe.", "positive": "Overview of North Ecliptic Pole Deep multi-wavelength Survey (NEP-Deep): The recent updates of the North Ecliptic Pole deep (0.5~deg$^2$, NEP-Deep)\nmulti-wavelength survey covering from X-ray to radio-wave is presented. The\nNEP-Deep provides us with several thousands of 15~$\\mu$m or 18~$\\mu$m selected\nsample of galaxies, which is the largest sample ever made at this wavelengths.\nA continuous filter coverage in the mid-infrared wavelength (7, 9, 11, 15, 18,\nand 24~$\\mu$m) is unique and vital to diagnose the contributions from\nstarbursts and AGNs in the galaxies out to $z$=2.The new goal of the project is\nto resolve the nature of the cosmic star formation history at the violent epoch\n(e.g. $z$=1--2), and to find a clue to understand its decline from $z$=1 to\npresent universe by utilizing the unique power of the multi-wavelength survey.\nThe progress in this context is briefly mentioned." }, { "anchor": "ABYSS I: Targeting strategy for APOGEE & BOSS young star survey in\n SDSS-V: The fifth iteration of the Sloan Digital Sky Survey (SDSS-V) is set to obtain\noptical and near-infrared spectra of $\\sim$5 million stars of all ages and\nmasses throughout the Milky Way. As a part of these efforts, APOGEE & BOSS\nYoung Star Survey (ABYSS) will observe $\\sim10^5$ stars with ages $<$30 Myr\nthat have been selected using a set of homogeneous selection functions that\nmake use of different tracers of youth. The ABYSS targeting strategy we\ndescribe in this paper is aimed to provide the largest spectroscopic census of\nyoung stars to-date. It consists of 8 different types of selection criteria\nthat take the position on the HR diagram, infrared excess, variability, as well\nas the position in phase space in consideration. The resulting catalog of\n$\\sim$200,000 sources (of which a half are expected to be observed) provides\nrepresentative coverage of the young Galaxy, including both nearby diffuse\nassociations as well as more distant massive complexes, reaching towards the\ninner Galaxy and the Galactic center.", "positive": "The Halos and Environments of Nearby Galaxies (HERON) Survey IV:\n Complexity in the boxy galaxies NGC 720 and NGC 2768: The shapes of galaxies, in particular their outer regions, are important\nguideposts to their formation and evolution. Here we report on the discovery of\nstrongly box-shaped morphologies of the, otherwise well-studied, elliptical and\nlenticular galaxies NGC 720 and NGC 2768 from deep imaging. The boxiness is\nstrongly manifested in the shape parameter $A_4/a$ of $-0.04$ in both objects,\nand also significant center shifts of the isophotes of $\\sim$ 2--4 kpc are\nseen. One reason for such asymmetries commonly stated in the literature is a\nmerger origin, although the number of such cases is still sparse and the exact\nproperties of the individual boxy objects is highly diverse. Indeed, for NGC\n2768, we identify a progenitor candidate (dubbed Pelops) in the residual\nimages, which appears to be a dwarf satellite that is currently merging with\nNGC 2768. At its absolute magnitude of M$_r$ of $-$12.2 mag, the corresponding\nSersic radius of 2.4 kpc is more extended than those of typical dwarf galaxies\nfrom the literature. However, systematically larger radii are known to occur in\nsystems that are in tidal disruption. This finding is bolstered by the presence\nof a tentative tidal stream feature on archival GALEX data. Finally, further\nstructures in the fascinating host galaxy comprise rich dust lanes and a\nvestigial X-shaped bulge component." }, { "anchor": "Two Growing Modes and the Morphology-Quiescence Relation in Galaxies: Quiescence in galaxies correlates strongly with the central\ndensity/morphology of the stellar distribution. We investigate two possible\nexplanations for this morphology-quiescence relation: 1) the central density\nresults from a dissipative core-building event (\"compaction\") that feeds an AGN\nthat quenches the galaxy and 2) the central density results from inside-out\ngrowth by galaxy-wide star formation that is quenched by processes unrelated to\nthe central density. We aim to distinguish these two scenarios using the MaNGA\nsurvey to determine profiles of stellar age, specific star formation rate\n(sSFR) and gas phase metallicity (O/H) as a function of stellar mass surface\ndensity within 1 kpc (Sigma_1kpc) and total stellar mass (M*). We find that\ngradients in age, sSFR and O/H depend on the galaxy's position on the\nSigma_1kpc-M* diagram, suggesting at least two evolutionary pathways. The first\npathway consists of galaxies with low Sigma_1kpc for their M* whose centres are\nold, metal-rich and suppressed in sSFR compared to their outskirts, consistent\nwith the inside-out growth scenario. The second pathway, consistent with a\ncompaction-like core-building scenario, consists of galaxies with higher\nSigma_1kpc for their M*, whose centres are younger, enhanced in sSFR and\nmetal-deficient compared to their outskirts. Moreover, the WISE-selected AGN\nfraction peaks in the same area of the Sigma_1kpc-M* diagram as the\ncore-building pathway. The sSFR profiles of the quiescent population suggest\nthat galaxies on the compaction-like path quench uniformly, while those on the\ninside-out growing path quench their centres first. Our results imply that both\npathways contribute to the morphology-quiescence relation.", "positive": "Nano-diamonds in proto-planetary discs: Life on the edge: Nano-diamonds remain an intriguing component of the dust in the few sources\nwhere they have been observed in emission. This work focusses on the\nnano-diamonds observed in circumstellar discs and is an attempt to derive\ncritical information about their possible sizes, compositions, and evolution\nusing a recently-derived set of optical constants. The complex indices of\nrefraction of nano-diamonds and their optical properties (the efficiency\nfactors Qext, Qsca, Qabs, and Qpr) were used to determine their temperatures,\nlifetimes, and drift velocities as a function of their radii (0.5-100 nm),\ncomposition (surface hydrogenation and irradiated states), and distance from\nthe central stars in circumstellar regions. The nano-diamond temperature\nprofiles were determined for the stars HR 4049, Elias 1, and HD 97048 in the\noptically-thin limit. The results indicate that large nano-diamonds (a = 30 -\n100 nm) are the hottest and therefore the least resistant in the inner disc\nregions (~ 10-50 AU), while small (a < 10 nm) fully-hydrogenated nano-diamonds\nremain significantly cooler in these same regions. We discuss these results\nwithin the context of nano-diamond formation in circumstellar discs. Large\nnano-diamonds, being the hottest, are most affected by the stellar radiation\nfield, however, the effects of radiation pressure appear to be insufficient to\nmove them out of harm's way. The nano-diamonds that best survive and therefore\nshine in the inner regions of proto-planetary discs are then seemingly small (a\n< 10 nm), hydrogenated, and close in size to pre-solar nano-diamonds (a ~ 1.4\nnm). Nevertheless, it does not yet appear possible to reconcile their existence\nthere with their seemingly short lifetimes in such regions." }, { "anchor": "Gravitational Instabilities in Two-Component Galaxy Disks with Gas\n Dissipation: Growth rates for gravitational instabilities in a thick disk of gas and stars\nare determined for a turbulent gas that dissipates on the local crossing time.\nThe scale heights are derived from vertical equilibrium. The accuracy of the\nusual thickness correction, 1/(1+kH), is better than 6% in the growth rate when\ncompared to exact integrations for the gravitational acceleration in the disk.\nGas dissipation extends the instability to small scales, removing the minimum\nJeans length. This makes infinitesimally thin disks unstable for all Toomre-Q\nvalues, and reasonably thick disks stable at high Q primarily because of\nthickness effects. The conventional gas+star threshold, Qtot increases from ~1\nwithout dissipation to 2 or 3 when dissipation has a rate equal to the crossing\nrate over a perturbation scale. Observations of Qtot~2-3 and the presence of\nsupersonic turbulence suggest that disks are unstable over a wide range of\nscales. Such instabilities drive spiral structure if there is shear and clumpy\nstructure if shear is weak; they may dominate the generation of turbulence.\nFeedback regulation of Qtot is complex because the stellar component does not\ncool; the range of spiral strengths from multiple arm to flocculent galaxies\nsuggests that feedback is weak. Gravitational instabilities may have a\nconnection to star formation even when the star formation rate scales directly\nwith the molecular mass because the instabilities return dispersed gas to\nmolecular clouds and complete the cycle of cloud formation and destruction. The\nmass flow to dense clouds by instabilities can be 10 times larger than the star\nformation rate.", "positive": "CO Multi-line Imaging of Nearby Galaxies (COMING). X. Physical\n conditions of molecular gas and the local SFR-Mass relation: We investigate the molecular gas properties of galaxies across the main\nsequence of star-forming (SF) galaxies in the local Universe using\n$^{12}$CO($J=1-0$) (hereafter $^{12}$CO) and $^{13}$CO($J=1-0$) ($^{13}$CO)\nmapping data of 147 nearby galaxies obtained in the COMING project, a legacy\nproject of the Nobeyama Radio Observatory. In order to improve signal-to-noise\nratios of both lines, we stack all the pixels where $^{12}$CO emission is\ndetected after aligning the line center expected from the first-moment map of\n$^{12}$CO. As a result, $^{13}$CO emission is successfully detected in 80\ngalaxies with a signal-to-noise ratio larger than three. The error-weighted\nmean of integrated-intensity ratio of $^{12}$CO to $^{13}$CO lines ($R_{1213}$)\nof the 80 galaxies is $10.9$ with a standard deviation of $7.0$. We find that\n(1) $R_{1213}$ positively correlates to specific star-formation rate (sSFR)\nwith a correlation coefficient of $0.46$, and (2) both flux ratio of IRAS\n60~$\\mu$m to 100~$\\mu$m ($f_{60}/f_{100}$) and inclination-corrected linewidth\nof $^{12}$CO stacked spectra ($\\sigma_{{\\rm ^{12}CO},i}$) also correlate with\nsSFR for galaxies with the $R_{1213}$ measurement. Our results support the\nscenario where $R_{1213}$ variation is mainly caused by the changes in\nmolecular-gas properties such as temperature and turbulence. The consequent\nvariation of CO-to-H$_2$ conversion factor across the SF main sequence is not\nlarge enough to completely extinguish the known correlations between sSFR and\n$M_{\\rm mol}/M_{\\rm star}$ ($\\mu_{\\rm mol}$) or star-formation efficiency (SFE)\nreported in previous studies, while this variation would strengthen (weaken)\nthe sSFR-SFE (sSFR-$\\mu_{\\rm mol}$) correlation." }, { "anchor": "A dormant, overmassive black hole in the early Universe: Recent observations have found a large number of supermassive black holes\nalready in place in the first few hundred million years after Big Bang. The\nchannels of formation and growth of these early, massive black holes are not\nclear, with scenarios ranging from heavy seeds to light seeds experiencing\nbursts of high accretion rate. Here we present the detection, from the JADES\nsurvey, of broad Halpha emission in a galaxy at z=6.68, which traces a black\nhole with mass of ~ 4 * 10^8 Msun and accreting at a rate of only 0.02 times\nthe Eddington limit. The host galaxy has low star formation rate (~ 1 Msun/yr,\na factor of 3 below the star forming main sequence). The black hole to stellar\nmass ratio is ~ 0.4, i.e. about 1,000 times above the local relation, while the\nsystem is closer to the local relations in terms of dynamical mass and velocity\ndispersion of the host galaxy. This object is most likely the tip of the\niceberg of a much larger population of dormant black holes around the epoch of\nreionisation. Its properties are consistent with scenarios in which short\nbursts of super-Eddington accretion have resulted in black hole overgrowth and\nmassive gas expulsion from the accretion disk; in between bursts, black holes\nspend most of their life in a dormant state.", "positive": "Search for 7Be in the outburst of four recent novae: Following the recent detection of 7Be in the outburst spectra of Classical\nNovae we report the search for this isotope in the outbursts of four recent\nbright novae by means of high resolution UVES observations. The 7BeII 313.0583,\n313.1228 nm doublet resonance lines are detected in the high velocity\ncomponents of Nova Mus 2018 and ASASSN-18fv during outburst. On the other hand\n7BeII is neither detected in ASASSN-17hx and possibly nor in Nova Cir 2018,\ntherefore showing that the 7BeII is not always ejected in the thermonuclear\nrunaway. Taking into account the 7Be decay we find X(7Be)/X(H) approx 1.5 x10\n^{-5} and 2.2 x 10 ^{-5} in Nova Mus 2018 and ASASSN-18fv, respectively. A\nvalue of 7Be/H about 2 x10 ^{-5} is found in 5 out of the 7 extant measurements\nand it might be considered as a typical 7Be yield for novae. However, this\nvalue is almost one order of magnitude larger than predicted by current\ntheoretical models. We argue that the variety of high 7Be/H abundances could be\noriginated in a higher than solar content of 3He in the donor star. The cases\nwith 7Be not detected might be related to a small mass of the WD or to\nrelatively little mixing with the core material of the WD. The 7Be /H, or\n7Li/H, abundance is about 4 dex above meteoritic thus confirming the novae as\nthe main sources of 7Li in the Milky Way." }, { "anchor": "From 'bathtub' galaxy evolution models to metallicity gradients: We model gas phase metallicity radial profiles of galaxies in the local\nUniverse by building on the `bathtub' chemical evolution formalism - where a\ngalaxy's gas content is determined by the interplay between inflow, star\nformation and outflows. In particular, we take into account inside-out disc\ngrowth and add physically-motivated prescriptions for radial gradients in star\nformation efficiency (SFE). We fit analytical models against the metallicity\nradial profiles of low-redshift star-forming galaxies in the mass range\n$\\log(M_\\star/M_\\odot)$ = [9.0-11.0] derived by Belfiore et al. 2017, using\ndata from the MaNGA survey. The models provide excellent fits to the data and\nare capable of reproducing the change in shape of the radial metallicity\nprofiles, including the flattening observed in the centres of massive galaxies.\nWe derive the posterior probability distribution functions for the model\nparameters and find significant degeneracies between them. The parameters\ndescribing the disc assembly timescale are not strongly constrained from the\nmetallicity profiles, while useful constrains are obtained for the SFE (and its\nradial dependence) and the outflow loading factor. The inferred value for the\nSFE is in good agreement with observational determinations. The inferred\noutflow loading factor is found to decrease with stellar mass, going from\nnearly unity at $\\log(M_\\star/M_\\odot) = 9.0$ to close to zero at\n$\\log(M_\\star/M_\\odot) =11.0$, in general agreement with previous empirical\ndeterminations. These values are the lowest we can obtain for a\nphysically-motivated choice of initial mass function and metallicity\ncalibration. We explore alternative choices which produce larger loading\nfactors at all masses, up to order unity at the high-mass end.", "positive": "Correlations between H$\u03b1$ Equivalent Width and Galaxy Properties at\n $z = 0.47$: Physical or Selection-driven?: The H$\\alpha$ equivalent width (EW) is an observational proxy for specific\nstar formation rate (sSFR) and a tracer of episodic star-formation activity.\nPrevious assessments show that EW strongly anti-correlates with stellar mass as\n$M^{-0.25}$ similar to the sSFR -- stellar mass relation. However, such a\ncorrelation may be driven/formed by selection effects. In this study, we\ninvestigate how H$\\alpha$ EWs correlate with galaxy properties and how\nselection biases could alter such correlations using a $z = 0.47$\nnarrowband-selected sample of 1572 H$\\alpha$ emitters from the Ly$\\alpha$\nGalaxies in the Epoch of Reionization (LAGER) survey. The sample covers 3\ndeg$^2$ of COSMOS and $1.1\\times10^5$ cMpc$^3$. We assume an intrinsic EW\ndistribution to form mock samples of H$\\alpha$ emitters (HAEs) and propagate\nthe selection criteria to match observations, giving us control on how\nselection biases can affect the underlying results. We find EW intrinsically\ncorrelates with stellar mass as $W_0 \\propto M^{-0.16\\pm0.03}$ and decreases by\na factor of $\\sim 3$ from $10^{7}$ to $10^{10}$ M$_\\odot$. We find low-mass\nHAEs to be $\\sim 320$ times more likely to have rest-frame EW$ > 200$\\AA\ncompared to high-mass HAEs. Combining the intrinsic EW -- stellar mass\ncorrelation with an observed SMF correctly reproduces the observed H$\\alpha$\nLF, while not correcting for selection effects underestimates the number of\nbright HAEs. This suggests that the intrinsic EW -- stellar mass correlation is\nphysically significant and reproduces three statistical distributions of galaxy\npopulations (LF, SMF, EW distribution). At lower masses, we find there are more\nhigh-EW outliers compared to high masses, even after taking into account\nselection effects. Our results suggest that high sSFR outliers indicative of\nbursty SF activity are intrinsically more prevalent in low-mass HAEs and not a\nbyproduct of selection effects." }, { "anchor": "Forward-modelling the Luminosity, Distance, and Size distributions of\n the Milky Way Satellites: We use \\texttt{GRUMPY}, a simple regulator-type model for dwarf galaxy\nformation and evolution, to forward model the dwarf galaxy satellite population\nof the Milky Way (MW) using the Caterpillar zoom-in simulation suite. We show\nthat luminosity and distance distributions of the model satellites are\nconsistent with the distributions measured in the DES, PS1 and SDSS surveys,\neven without including a model for the orphan galaxies. We also show that our\nmodel for dwarf galaxy sizes can simultaneously reproduce the observed {\\it\ndistribution} of stellar half-mass radii, $r_{1/2}$, of the MW satellites and\nthe overall $r_{1/2}-M_\\star$ relation exhibited by observed dwarf galaxies.\nThe model predicts that some of the observed faint stellar systems with\n$r_{1/2}<10$ pc are ultra-faint dwarf galaxies. Scaling of the stellar mass\n$M_\\star$ and peak halo mass $M_{\\rm peak}$ for the model satellites is not\ndescribed by a power law, but has a clear flattening of $M_\\star-M_{\\rm peak}$\nscaling at $M_{\\rm peak}<10^8\\,M_\\odot$ imprinted by reionization. As a result,\nthe fraction of low mass haloes ($M_{\\rm peak} < 10^8\\, M_\\odot$) hosting\ngalaxies with $M_V<0$ is predicted to be 50% at $M_{\\rm peak} \\sim 3.6 \\times\n10^7\\,M_\\odot$. We find that such high fraction at that halo mass helps to\nreproduce the number of dwarf galaxies discovered recently in the HSC-SSP\nsurvey. Using the model we forecast that there should be the total of\n$440^{+201}_{-147}$ (68\\% confidence interval) MW satellites with $M_V < 0$ and\n$r_{1/2} > 10$ pc within 300 kpc and make specific predictions for the HSC-SSP,\nDELVE-WIDE and LSST surveys.", "positive": "Self-gravity, resonances and orbital diffusion in stellar discs: Fluctuations in a stellar system's gravitational field cause the orbits of\nstars to evolve. The resulting evolution of the system can be computed with the\norbit-averaged Fokker-Planck equation once the diffusion tensor is known. We\npresent the formalism that enables one to compute the diffusion tensor from a\ngiven source of noise in the gravitational field when the system's dynamical\nresponse to that noise is included. In the case of a cool stellar disc we are\nable to reduce the computation of the diffusion tensor to a one-dimensional\nintegral. We implement this formula for a tapered Mestel disc that is exposed\nto shot noise and find that we are able to explain analytically the principal\nfeatures of a numerical simulation of such a disc. In particular the formation\nof narrow ridges of enhanced density in action space is recovered. As the\ndisc's value of Toomre's $Q$ is reduced and the disc becomes more responsive,\nthere is a transition from a regime of heating in the inner regions of the disc\nthrough the inner Lindblad resonance to one of radial migration of\nnear-circular orbits via the corotation resonance in the intermediate regions\nof the disc. The formalism developed here provides the ideal framework in which\nto study the long-term evolution of all kinds of stellar discs." }, { "anchor": "VALES VII: Molecular and ionized gas properties in pressure balanced\n interstellar medium of starburst galaxies at z ~ 0.15: Context. Spatially resolved observations of the ionized and molecular gas are\ncritical for understanding the physical processes that govern the interstellar\nmedium (ISM) in galaxies. Aims. To study the morpho-kinematic properties of the\nionized and molecular gas in three dusty starburst galaxies at $z = 0.12-0.17$\nto explore the relation between molecular ISM gas phase dynamics and the\nstar-formation activity. Methods. We analyse $\\sim$kpc-scale ALMA CO(1--0) and\nseeing limited SINFONI Paschen-$\\alpha$ observations. We use a dynamical mass\nmodel, which accounts for beam-smearing effects, to constrain the CO-to-H$_2$\nconversion factor. Results. One starburst galaxy shows irregular morphology\nwhich may indicate a major merger, while the other two systems show disc-like\nmorpho-kinematics. The two disc-like starbursts show molecular gas velocity\ndispersion values comparable with that seen in local LIRG/ULIRGs, but in an ISM\nwith molecular gas fraction and surface density values consistent to that\nreported for local star-forming galaxies. These molecular gas velocity\ndispersion values can be explained by assuming vertical pressure equilibrium.\nThe star-formation activity is correlated with the molecular gas content\nsuggesting depletion times of the order of $\\sim 0.1-1$ Gyr. The star formation\nrate surface density ($\\Sigma_{\\rm SFR}$) correlates with the ISM pressure set\nby self-gravity ($P_{\\rm grav}$) following a power law with an exponent close\nto 0.8. Conclusions. In dusty disc-like starburst galaxies, our data support\nthe scenario in which the molecular gas velocity dispersion values are driven\nby the ISM pressure set by self-gravity, responsible to maintain the vertical\npressure balance. The correlation between $\\Sigma_{\\rm SFR}$ and $P_{\\rm grav}$\nsuggests that, in these dusty starbursts galaxies, the star formation activity\narises as a consequence of the ISM pressure balance.", "positive": "Comparing the Inner and Outer Star Forming Complexes in the Nearby\n Spiral Galaxies NGC 628, NGC 5457 and NGC 6946 using UVIT Observations: We present a far-UV (FUV) study of the star-forming complexes (SFCs) in three\nnearby galaxies using the Ultraviolet Imaging Telescope (UVIT). The galaxies\nare close to face-on and show significant outer disk star formation. Two of\nthem are isolated (NGC 628, NGC 6946), and one is interacting with distant\ncompanions (NGC 5457). We compared the properties of the SFCs inside and\noutside the optical radius (R$_{25}$). We estimated the sizes, star formation\nrates (SFRs), metallicities, and the Toomre Q parameter of the SFCs. We find\nthat the outer disk SFCs are at least ten times smaller in area than those in\nthe inner disk. The SFR per unit area ($\\Sigma_{SFR}$) in both regions have\nsimilar mean values, but the outer SFCs have a much smaller range of\n$\\Sigma_{SFR}$. They are also metal-poor compared to the inner disk SFCs. The\nFUV emission is well correlated with the neutral hydrogen gas (\\HI)\ndistribution and is detected within and near several \\HI~holes. Our estimation\nof the Q parameter in the outer disks of the two isolated galaxies suggests\nthat their outer disks are stable (Q$>$1). However, their FUV images indicate\nthat there is ongoing star formation in these regions. This suggests that there\nmay be some non-luminous mass or dark matter in their outer disks, which\nincreases the disk surface density and supports the formation of local\ngravitational instabilities. In the interacting galaxy, NGC 5457, the baryonic\nsurface density is sufficient (Q$<$1) to trigger local disk instabilities in\nthe outer disk." }, { "anchor": "Ionizing feedback from massive stars in massive clusters III: Disruption\n of partially unbound clouds: We extend our previous SPH parameter study of the effects of photoionization\nfrom O-stars on star-forming clouds to include initially unbound clouds. We\ngenerate a set of model clouds in the mass range $10^{4}-10^{6}$M$_{\\odot}$\nwith initial virial ratios $E_{\\rm kin}/E_{\\rm pot}$=2.3, allow them to form\nstars, and study the impact of the photoionizing radiation produced by the\nmassive stars. We find that, on the 3Myr timescale before supernovae are\nexpected to begin detonating, the fractions of mass expelled by ionizing\nfeedback is a very strong function of the cloud escape velocities. High-mass\nclouds are largely unaffected dynamically, while lower-mass clouds have large\nfractions of their gas reserves expelled on this timescale. However, the\nfractions of stellar mass unbound are modest and significant portions of the\nunbound stars are so only because the clouds themselves are initially partially\nunbound. We find that ionization is much more able to create well-cleared\nbubbles in the unbound clouds, owing to their intrinsic expansion, but that the\npresence of such bubbles does not necessarily indicate that a given cloud has\nbeen strongly influenced by feedback. We also find, in common with the bound\nclouds from our earlier work, that many of the systems simulated here are\nhighly porous to photons and supernova ejecta, and that most of them will\nlikely survive their first supernova explosions.", "positive": "JWST observations of $^{13}$CO$_{2}$ ice: Tracing the chemical\n environment and thermal history of ices in protostellar envelopes: The structure and composition of simple ices can be modified during stellar\nevolution by protostellar heating. Key to understanding the involved processes\nare thermal and chemical tracers that can diagnose the history and environment\nof the ice. The 15.2 $\\mu$m bending mode of $^{12}$CO$_2$ has proven to be a\nvaluable tracer of ice heating events but suffers from grain shape and size\neffects. A viable alternative tracer is the weaker $^{13}$CO$_2$ isotopologue\nband at 4.39 $\\mu$m which has now become accessible at high S/N with the\n$\\textit{James Webb}$ Space Telescope (JWST). We present JWST NIRSpec\nobservations of $^{13}$CO$_2$ ice in five deeply embedded Class 0 sources\nspanning a wide range in luminosities (0.2 - 10$^4$ L$_{\\odot}$ ) taken as part\nof the Investigating Protostellar Accretion Across the Mass Spectrum (IPA)\nprogram. The band profiles vary significantly, with the most luminous sources\nshowing a distinct narrow peak at 4.38 $\\mu$m. We first apply a\nphenomenological approach and show that a minimum of 3-4 Gaussian profiles are\nneeded to fit the $^{13}$CO$_2$ absorption feature. We then combine these\nfindings with laboratory data and show that a 15.2 $\\mu$m $^{12}$CO$_2$ band\ninspired five-component decomposition can be applied for the isotopologue band\nwhere each component is representative of CO$_2$ ice in a specific molecular\nenvironment. The final solution consists of cold mixtures of CO$_2$ with\nCH$_3$OH, H$_2$O and CO as well as segregated heated pure CO$_2$ ice. Our\nresults are in agreement with previous studies of the $^{12}$CO$_2$ ice band,\nfurther confirming that $^{13}$CO$_{2}$ is a useful alternative tracer of\nprotostellar heating events. We also propose an alternative solution consisting\nonly of heated CO$_2$:CH$_3$OH and CO$_2$:H$_2$O ices and warm pure CO$_2$ ice\nfor decomposing the ice profiles of the two most luminous sources in our\nsample." }, { "anchor": "3D extinction mapping of the Milky Way using Convolutional Neural\n Networks: Presentation of the method and demonstration in the Carina Arm\n region: Context. Several methods have been proposed to build 3D extinction maps of\nthe Milky Way (MW), most often based on Bayesian approaches. Although some\nstudies employed machine learning (ML) methods in part of their procedure, or\nto specific targets, no 3D extinction map of a large volume of the MW solely\nbased on a Neural Network method has been reported so far. Aims. We aim to\napply deep learning as a solution to build 3D extinction maps of the MW.\nMethods. We built a convolutional neural network (CNN) using the CIANNA\nframework, and trained it with synthetic 2MASS data. We used the Besan\\c{c}on\nGalaxy model to generate mock star catalogs, and 1D Gaussian random fields to\nsimulate the extinction profiles. From these data we computed color-magnitude\ndiagrams (CMDs) to train the network, using the corresponding extinction\nprofiles as targets. A forward pass with observed 2MASS CMDs provided\nextinction profile estimates for a grid of lines of sight. Results. We trained\nour network with data simulating lines of sight in the area of the Carina\nspiral arm tangent and obtained a 3D extinction map for a large sector in this\nregion ($l = 257 - 303$ deg, $|b| \\le 5$ deg), with distance and angular\nresolutions of $100$ pc and $30$ arcmin, respectively, and reaching up to $\\sim\n10$ kpc. Although each sightline is computed independently in the forward\nphase, the so-called fingers-of-God artifacts are weaker than in many other 3D\nextinction maps. We found that our CNN was efficient in taking advantage of\nredundancy across lines of sight, enabling us to train it with only 9\nsightlines simultaneously to build the whole map. Conclusions. We found deep\nlearning to be a reliable approach to produce 3D extinction maps from large\nsurveys. With this methodology, we expect to easily combine heterogeneous\nsurveys without cross-matching, and therefore to exploit several surveys in a\ncomplementary fashion.", "positive": "A new synthetic library of the Near-Infrared CaII triplet indices.\n I.Index Definition, Calibration and Relations with stellar atmospheric\n parameters: Adopting the SPECTRUM package, we have synthesized a set of 2,890\nNear-InfraRed (NIR) synthetic spectra with a resolution and wavelength sampling\nsimilar to the SDSS and the forthcoming LAMOST spectra. During the synthesis,\nwe have applied the `New grids of ATLAS9 Model Atmosphere' to provide a grid of\nlocal thermodynamic equilibrium (LTE) model atmospheres. This synthetic stellar\nlibrary is composed of 1,350 solor scaled abundance (SSA) and 1,530 non-solar\nscaled abundance (NSSA) spectra, grounding on which we have defined a new set\nof NIR CaII triplet indices and an index CaT as the sum of the three. Then,\nthese defined indices have been automatically measured on the synthetic spectra\nand calibrated with the indices computed on the observational spectra from the\nINDO-U.S. stellar library. In order to check the effect of alpha-element\nenhancement on the so-defined CaII indices, we have compared indices measured\non the SSA spectra with those on the NSSA ones at the same terns of stellar\nparameters (Teff, log g, [Fe/H]), and luckily, little influences of\nalpha-element enhancement has been found. Furthermore, comparisons of synthetic\nindices with the observational ones from the INDO-U.S. spectra, the SDSS-DR7,\nand DR8 spectroscopic survey have been presented respectively for dwarfs and\ngiants in detail. Finally, a new synthetic library of NIR CaII indices has been\nfounded for deeper studies on the NIR waveband of stellar spectra, and is\nparticularly appropriate for the SDSS and the forthcoming LAMOST stellar\nspectra. Later on, we have regressed the strength of the CaT index as a\nfunction of stellar parameters for both dwarfs and giants after a series of\nexperimental investigations into relations of the indices with stellar\nparameters. Ultimately, a supplemental experimentation has been carried out to\nshow that spectral noises do have effects on our set of NIR CaII indices." }, { "anchor": "PISCO: The Pmas/ppak Integral-field Supernova hosts COmpilation: We present the Pmas/ppak Integral-field Supernova hosts COmpilation (PISCO)\nwhich comprises Integral Field Spectroscopy (IFS) of 232 supernova (SN) host\ngalaxies, that hosted 272 SNe, observed over several semesters with the 3.5m\ntelescope at the Calar Alto Observatory (CAHA). PISCO is the largest collection\nof SN host galaxies observed with wide-field IFS, totaling 466,347 individual\nspectra covering a typical spatial resolution of $\\sim$380 pc. While focused\nstudies regarding specific SN Ia- related topics will be published elsewhere,\nthis paper aims to present the properties of the SN environments with stellar\npopulation (SP) synthesis and the gas-phase ISM, providing additional results\nseparating stripped-envelope SNe into their subtypes. With 11,270 HII regions\ndetected in all galaxies, we present for the first time an HII region\nstatistical analysis, that puts HII regions that have hosted SNe in context\nwith all other SF clumps within their galaxies. SNe Ic are associated to more\nmetal-rich, higher EW(H{\\alpha}) and higher SF rate environments within their\nhost galaxies than the mean of all HII regions detected within each host, on\ncontrary SNe IIb occur at the most different environments compared to other CC\nSNe types. We find two clear components of young and old SP at SNe IIn\nlocations. We find that SNe II fast-decliners (IIL) tend to explode at\nlocations where {\\Sigma}SFR is more intense. Finally, we outline how a future\ndedicated IFS survey of galaxies in parallel to an untargeted SN search would\novercome the biases in current environmental studies.", "positive": "Improved mass constraints for two nearby strong-lensing elliptical\n galaxies from Hubble Space Telescope Imaging: We analyse newly obtained Hubble Space Telescope (HST) imaging for two nearby\nstrong lensing elliptical galaxies, SNL-1 (z = 0.03) and SNL-2 (z = 0.05), in\norder to improve the lensing mass constraints. The imaging reveals previously\nunseen structure in both the lens galaxies and lensed images. For SNL-1 which\nhas a well resolved source, we break the mass-vs-shear degeneracy using the\nrelative magnification information, and measure a lensing mass of 9.49 $\\pm$\n0.15 $\\times$ 10$^{10}$ M$_{\\odot}$, a 7 per cent increase on the previous\nestimate. For SNL-2 the imaging reveals a bright unresolved component to the\nsource and this presents additional complexity due to possible AGN microlensing\nor variability. We tentatively use the relative magnification information to\nconstrain the contribution from SNL-2's nearby companion galaxy, measuring a\nlensing mass of 12.59 $\\pm$ 0.30 $\\times$ 10$^{10}$ M$_{\\odot}$, a 9 per cent\nincrease in mass. Our improved lens modelling reduces the mass uncertainty from\n5 and 10 per cent to 2 and 3 per cent respectively. Our results support the\nconclusions of the previous analysis, with newly measured mass excess\nparameters of 1.17 $\\pm$ 0.09 and 0.96 $\\pm$ 0.10 for SNL-1 and SNL-2, relative\nto a Milky-Way like (Kroupa) initial mass function." }, { "anchor": "Placing LOFAR-detected quasars in CIV emission space: implications for\n winds, jets and star formation: We present an investigation of the low-frequency radio and ultraviolet\nproperties of a sample of $\\simeq$10,500 quasars from the Sloan Digital Sky\nSurvey Data Release 14, observed as part of the first data release of the\nLow-Frequency-Array Two-metre Sky Survey. The quasars have redshifts $1.5 < z <\n3.5$ and luminosities $44.6 < \\log(L_{\\text{bol}}/\\text{erg s}^{-1}) < 47.2$.\nWe employ ultraviolet spectral reconstructions based on an independent\ncomponent analysis to parametrize the CIV$\\lambda$1549-emission line that is\nused to infer the strength of accretion disc winds, and the HeII$\\lambda$1640\nline, an indicator of the soft X-ray flux. We find that radio-detected quasars\nare found in the same region of CIV blueshift versus equivalent-width space as\nradio-undetected quasars, but that the loudest, most luminous and largest radio\nsources exist preferentially at low CIV blueshifts. Additionally, the\nradio-detection fraction increases with blueshift whereas the radio-loud\nfraction decreases. In the radio-quiet population, we observe a range of HeII\nequivalent widths as well as a Baldwin effect with bolometric luminosity,\nwhilst the radio-loud population has mostly strong HeII, consistent with a\nstronger soft X-ray flux. The presence of strong HeII is a necessary but not\nsufficient condition to detect radio-loud emission suggesting some degree of\nstochasticity in jet formation. Using energetic arguments and Monte Carlo\nsimulations, we explore the plausibility of winds, compact jets and star\nformation as sources of the radio quiet emission, ruling out none. The\nexistence of quasars with similar ultraviolet properties but differing radio\nproperties suggests, perhaps, that the radio and ultraviolet emission is\ntracing activity occurring on different timescales.", "positive": "Polarized Light from Massive Protoclusters (POLIMAP). I. Dissecting the\n role of magnetic fields in the massive infrared dark cloud G28.37+0.07: Magnetic fields may play a crucial role in setting the initial conditions of\nmassive star and star cluster formation. To investigate this, we report\nSOFIA-HAWC+ $214\\:\\mu$m observations of polarized thermal dust emission and\nhigh-resolution GBT-Argus C$^{18}$O(1-0) observations toward the massive\nInfrared Dark Cloud (IRDC) G28.37+0.07. Considering the local dispersion of\n$B$-field orientations, we produce a map of $B$-field strength of the IRDC,\nwhich exhibits values between $\\sim0.03 - 1\\:$mG based on a refined\nDavis-Chandrasekhar-Fermi (r-DCF) method proposed by Skalidis \\& Tassis.\nComparing to a map of inferred density, the IRDC exhibits a $B-n$ relation with\na power law index of $0.51\\pm0.02$, which is consistent with a scenario of\nmagnetically-regulated anisotropic collapse. Consideration of the mass-to-flux\nratio map indicates that magnetic fields are dynamically important in most\nregions of the IRDC. A virial analysis of a sample of massive, dense cores in\nthe IRDC, including evaluation of magnetic and kinetic internal and surface\nterms, indicates consistency with virial equilibrium, sub-Alfv\\'enic conditions\nand a dominant role for $B-$fields in regulating collapse. A clear alignment of\nmagnetic field morphology with direction of steepest column density gradient is\nalso detected. However, there is no preferred orientation of protostellar\noutflow directions with the $B-$field. Overall, these results indicate that\nmagnetic fields play a crucial role in regulating massive star and star cluster\nformation and so need to be accounted for in theoretical models of these\nprocesses." }, { "anchor": "Droplets I: Pressure-Dominated Sub-0.1 pc Coherent Structures in L1688\n and B18: We present the observation and analysis of newly discovered coherent\nstructures in the L1688 region of Ophiuchus and the B18 region of Taurus. Using\ndata from the Green Bank Ammonia Survey (GAS), we identify regions of high\ndensity and near-constant, almost-thermal, velocity dispersion. Eighteen\ncoherent structures are revealed, twelve in L1688 and six in B18, each of which\nshows a sharp \"transition to coherence\" in velocity dispersion around its\nperiphery. The identification of these structures provides a chance to study\nthe coherent structures in molecular clouds statistically. The identified\ncoherent structures have a typical radius of 0.04 pc and a typical mass of 0.4\nMsun, generally smaller than previously known coherent cores identified by\nGoodman et al. (1998), Caselli et al. (2002), and Pineda et al. (2010). We call\nthese structures \"droplets.\" We find that unlike previously known coherent\ncores, these structures are not virially bound by self-gravity and are instead\npredominantly confined by ambient pressure. The droplets have density profiles\nshallower than a critical Bonnor-Ebert sphere, and they have a velocity (VLSR)\ndistribution consistent with the dense gas motions traced by NH3 emission.\nThese results point to a potential formation mechanism through pressure\ncompression and turbulent processes in the dense gas. We present a comparison\nwith a magnetohydrodynamic simulation of a star-forming region, and we\nspeculate on the relationship of droplets with larger, gravitationally bound\ncoherent cores, as well as on the role that droplets and other coherent\nstructures play in the star formation process.", "positive": "Modes of a stellar system I: ergodic systems: The excursions of star clusters and galaxies around statistical equilibria\nare studied. For a stable ergodic model Antonov's Hermitian operator on\nsix-dimensional phase space has the normal modes as its eigenfunctions. The\nexcitation energy of the system is just the sum of the (positive) energies\nassociated with each normal mode. Formulae are given for the DFs of modes,\nwhich are of the type first described by van Kampen rather than Landau, and\nLandau `modes' can be expressed as sums of van Kampen modes. Each van Kampen\nmode comprises the response of non-resonant stars to driving by the\ngravitational field of stars on a group of resonant tori, so its structure is\nsensitive to the degree of self gravity. The emergence of global distortions in\nN-body models when particles are started from an analytical equilibrium is\nexplained in terms of the interplay of normal modes. The positivity of modal\nenergies opens the way to modelling the thermal properties of clusters in close\nanalogy with those of crystals." }, { "anchor": "Isolated starless cores in IRDCs in the Hi-GAL survey: In a previous paper we identified cores within infrared dark clouds (IRDCs).\nWe regarded those without embedded sources as the least evolved, and labelled\nthem starless. Here we identify the most isolated starless cores and model them\nusing a three-dimensional, multi-wavelength, Monte Carlo, radiative transfer\ncode. We derive the cores' physical parameters and discuss the relation between\nthe mass, temperature, density, size and the surrounding interstellar radiation\nfield (ISRF) for the cores. The masses of the cores were found not to correlate\nwith their radial size or central density. The temperature at the surface of a\ncore was seen to depend almost entirely on the level of the ISRF surrounding\nthe core. No correlation was found between the temperature at the centre of a\ncore and its local ISRF. This was seen to depend, instead, on the density and\nmass of the core.", "positive": "The clustering of galaxies in the DESI imaging legacy surveys DR8: I.\n the luminosity and color dependent intrinsic clustering: In a recent study, we developed a method to model the impact of photometric\nredshift uncertainty on the two-point correlation function (2PCF). In this\nmethod, we can obtain both the intrinsic clustering strength and the\nphotometric redshift errors simultaneously by fitting the projected 2PCF with\ntwo integration depths along the line-of-sight. Here we apply this method to\nthe DESI Legacy Imaging Surveys Data Release 8 (LS DR8), the largest galaxy\nsample currently available. We separate galaxies into 20 samples in 8 redshift\nbins from $z=0.1$ to $z=1.0$, and a few $\\rm z$-band absolute magnitude bins,\nwith $M_{\\rm z} \\le -20$. These galaxies are further separated into red and\nblue sub-samples according to their $M^{0.5}_{\\rm r}-M^{0.5}_{\\rm z}$ colors.\nWe measure the projected 2PCFs for all these galaxy (sub-)samples, and fit them\nusing our photometric redshift 2PCF model. We find that the photometric\nredshift errors are smaller in red sub-samples than the overall population. On\nthe other hand, there might be some systematic photometric redshift errors in\nthe blue sub-samples, so that some of the sub-samples show significantly\nenhanced 2PCF at large scales. Therefore, focusing only on the red and all\n(sub-)samples, we find that the biases of galaxies in these (sub-)samples show\nclear color, redshift and luminosity dependencies, in that red brighter\ngalaxies at higher redshift are more biased than their bluer and low redshift\ncounterparts. Apart from the best fit set of parameters, $\\sigma_{z}$ and $b$,\nfrom this state-of-the-art photometric redshift survey, we obtain high\nprecision intrinsic clustering measurements for these 40 red and all galaxy\n(sub-)samples. These measurements on large and small scales hold important\ninformation regarding the cosmology and galaxy formation, which will be used in\nour subsequent probes in this series." }, { "anchor": "A bottom-up search for Lyman-continuum leakage in the Hubble Ultra Deep\n Field: Context: Studies of the production and escape of Lyman Continuum from\ngalaxies often rely on array of indirect observational tracers in preselection\nof candidate leakers.\n Aims: Here, we investigate how much ionizing radiation might be missed due to\nthese selection criteria by completely removing them and performing a search\nselected purely from rest-frame LyC emission; and how that affects our\nestimates of the ionizing background.\n Methods: We invert the conventional method and perform a bottom-up search for\nLyman-continuum leaking galaxies at redshifts $2 < z < 3.5$. Using archival\ndata from HST and VLT/MUSE, we run source finding software on UV-filter HST\nimages from the HUDF, and subject all detected sources to a series of tests to\neliminate those that are inconsistent with being ionizing sources.\n Results: We find 6 new and one previously identified candidate leakers with\nabsolute escape fractions ranging from 36% to 100%. Our filtering criteria\neliminate one object previously reported as a candidate ionizing emitter in the\nliterature, while we report non-detection in the rest frame Lyman continuum of\ntwo other previously reported sources. We find that our candidates make a\ncontribution to the metagalactic ionizing field of $\\log_{10}(\\epsilon_{\\nu}) =\n25.32(+0.25)(-0.21)$ and $25.29(+0.27)(-0.22)$ erg/s/Hz/cMpc$^3$ for the full\nset of candidates and for the 4 strongest candidates only; both values are\nhigher than but consistent with other recent figures in the literature.\n Conclusions: Our findings suggest that galaxies that do not meet the usual\nselection criteria may make a non-negligible contribution to the cosmic\nionizing field. We recommend that similar searches be carried out on a larger\nscale in well-studied fields with both UV and large ancillary data coverage,\nfor example in the full set of CANDELS fields.", "positive": "Hints of a disrupted binary dwarf galaxy in the Sagittarius stream: In this work, we look for evidence of a non-unity mass ratio binary dwarf\ngalaxy merger in the Sagittarius stream. Simulations of such a merger show\nthat, upon merging with a host, particles from the less-massive galaxy will\noften mostly be found in the extended stream and less-so in the central\nremnant. Motivated by these simulations, we use APOGEE DR17 chemical data from\napproximately 1100 stars in both the Sagittarius remnant and stream to look for\nevidence of contamination from a second dwarf galaxy. This search is initially\njustified by the idea that disrupted binary dwarf galaxies provide a possible\nexplanation of the Sagittarius bifurcation, and the location of the massive,\nchemically peculiar globular cluster NGC 2419 found within the stream of\nSagittarius. We separate the Sagittarius data into its remnant and stream and\ncompare the [Mg/Fe] content of the two populations. In particular, we select\n[Mg/Fe] to search for hints of unique star formation histories among our sample\nstars. Comparing the stream and remnant populations, we find regions have\ndistinct [Mg/Fe] distributions for fixed [Fe/H], in addition to distinct\nchemical tracks in [Mg/Fe] -- [Fe/H] abundance space. We show that there are\nlarge regions of the tracks for which the probability of the two samples being\ndrawn from the same distribution is very low (p < 0.05). Furthermore, we show\nthat the two tracks can be fit with unique star formation histories using\nsimple, one zone galactic chemical evolution models. While more work must be\ndone to discern whether the hypothesis presented here is true, our work hints\nat the possibility that Sagittarius may consist of two dwarf galaxy\nprogenitors." }, { "anchor": "A small radio galaxy at z=4.026: Less than $200$ radio-loud active galactic nuclei (AGN) are known above\nredshift $4$. Around $40$ of them have been observed at milliarcsecond (mas)\nscale resolution with very long baseline interferometry (VLBI) technique. Some\nof them are unresolved, compact, relativistically beamed objects, blazars with\njets pointing at small angles to the observer's line of sight. But there are\nalso objects with no sign of relativistic beaming possibly having larger jet\ninclination angles. In a couple of cases, X-ray observations indicate the\npresence of relativistic beaming in contrary to the VLBI measurements made with\nthe European VLBI Network (EVN). J1420$+$1205 is a prominent example, where our\n$30-100$ mas-scale enhanced Multi Element Remotely Linked Interferometer\nNetwork (e-MERLIN) radio observations revealed a rich structure reminiscent of\na small radio galaxy. It shows a bright hotspot which might be related to the\ndenser interstellar medium around a young galaxy at an early cosmological\nepoch.", "positive": "A Likely Super Massive Black Hole Revealed by its Einstein Radius in\n Hubble Frontier Fields Images: At cosmological distances, gravitational lensing can provide a direct\nmeasurement of supermassive black hole (SMBH) masses irrespective of their\nluminosities. Here, we directly estimate the mass of a SMBH in the brightest\ncluster galaxy (BCG) of MACS J1149+2223.5 at $z=0.54$ through one of the\nmultiply-lensed images of a background spiral galaxy at $z=1.49$ projected\nclose to the BCG. In this particular image, an intrinsically compact region in\none of the spiral arms is lensed into an arc that curves towards the BCG\ncenter. This arc has a radius of curvature of only $\\sim$0.\"6, betraying the\npresence of a local compact deflector. Its curvature is most simply reproduced\nby a point-like object with a mass of $8.4^{+4.3}_{-1.8}\\times10^{9}M_\\odot$,\nsimilar to SMBH masses in local elliptical galaxies having comparable\nluminosities. The SMBH is noticeably offset by $4.4\\pm0.3$ kpc from the BCG\nlight centre, plausibly the result of a kick imparted $\\sim2.0\\times10^7$ years\nago during the merger of two SMBHs, placing it just beyond the stellar core. A\nsimilar curvature can be produced by replacing the offset SMBH with a compact\ngalaxy having a mass of $\\sim2\\times 10^{10}M_\\odot$ within a cutoff radius of\n$<4$ kpc, and an unusually large $M/L>50(M/L)_\\odot$ to make it undetectable in\nthe deep Hubble Frontiers Fields image, at or close to the cluster redshift;\nsuch a lensing galaxy, however, perturbs the adjacent lensed images in an\nundesirable way." }, { "anchor": "Separating the conjoined red clump in the Galactic Bulge: Kinematics and\n Abundances: We have used the AAOMEGA spectrograph to obtain R $\\sim 1500$ spectra of 714\nstars that are members of two red clumps in the Plaut Window Galactic bulge\nfield $(l,b)=0^{\\circ},-8^{\\circ}$. We discern no difference between the clump\npopulations based on radial velocities or abundances measured from the Mg$b$\nindex. The velocity dispersion has a strong trend with Mg$b$-index metallicity,\nin the sense of a declining velocity dispersion at higher metallicity. We also\nfind a strong trend in mean radial velocity with abundance. Our red clump\nsample shows distinctly different kinematics for stars with [Fe/H] $<-1$, which\nmay plausibly be attributable to a minority classical bulge or inner halo\npopulation. The transition between the two groups is smooth. The\nchemo-dynamical properties of our sample are reminiscent of those of the Milky\nWay globular cluster system. If correct, this argues for no bulge/halo\ndichotomy and a relatively rapid star formation history. Large surveys of the\ncomposition and kinematics of the bulge clump and red giant branch are needed\nto define further these trends.", "positive": "X-ray and multiwavelength view of NGC 4278. A LINER-Seyfert connection?: (Abridged) Based on UV to X-ray and radio to UV flux ratios, some argue that\nlow ionization emission line regions (LINERs) and low luminosity AGN (LLAGN)\nare a scaled-down version of their more luminous predecessors Seyfert galaxies.\nOthers, based on the lack of X-ray short (hours) time-scale variability, the\nnon-detection of an iron line at 6.4 keV, and the faint UV emission, suggest\nthe truncation of the classical thin accretion disk in the inner regions of the\nAGN where a radiatively inefficient accretion flow (RIAF) structure forms. We\ninvestigate the LINER-Seyfert connection by studying the unabsorbed, AGN\npowered, LINER galaxy NGC 4278. We analyzed one XMM-Newton and seven Chandra\nX-ray observations of NGC 4278 spread over a three year period. We detected a\nflux increase by a factor of ~3 on a ~3 months time-scale and by a factor of 5\nbetween the faintest and the brightest observation separated by ~3 years.\nDuring only the XMM-Newton observation, where the highest flux level is\ndetected, we found a 10% flux increase on a ~1 hour time-scale. A combination\nof an absorbed power law (N(H)~10^20 cm^-2, Gamma~2.2) plus a thermal component\n(kT~0.6 keV) were able to fit the Chandra spectra. The XMM-Newton spectra,\nwhere the highest X-ray flux is detected, are well fitted with a single\nabsorbed power-law. No Fe K(alpha) emission line is detected at 6.4 keV. We\nconstructed SEDs based on simultaneous or quasi simultaneous observations and\ncompared them to LINER, radio-loud, and radio-quiet quasar SEDs. We find that\nat a low X-ray flux the NGC 4278 SED resembles that of typical LINER sources\nwhere the radio to X-ray emission can be considered as originating from a jet\nand/or RIAF, whereas at a high X-ray flux, NGC 4278 SED is more like a low\nluminosity Seyfert SED. Consequently, NGC 4278 could exhibit both LINER and\nSeyfert nuclear activity depending on the strength of its X-ray emission." }, { "anchor": "Large-scale environmental dependence of the abundance ratio of nitrogen\n to oxygen in blue, star-forming galaxies fainter than L*: We examine how the cosmic environment affects the chemical evolution of\ngalaxies in the Universe by comparing the N/O ratio of dwarf galaxies in voids\nwith dwarf galaxies in more dense regions. Ratios of the forbidden [O III] and\n[S II] transitions provide estimates of a region's electron temperature and\nnumber density. We estimate the abundances of oxygen and nitrogen using these\ntemperature and density estimates and the emission line fluxes [O II] 3727, [O\nIII] 4959, 5007, and [N II] 6548, 6584 with the direct Te method. Using\nspectroscopic observations from the Sloan Digital Sky Survey Data Release 7, we\nare able to estimate the N/O ratio in 42 void dwarf galaxies and 89 dwarf\ngalaxies in more dense regions. The N/O ratio for void dwarfs (Mr > -17) is\nslightly lower (12%) than for dwarf galaxies in denser regions. We also\nestimate the nitrogen and oxygen abundances of 2050 void galaxies and 3883\ngalaxies in more dense regions with Mr > -20. These somewhat brighter galaxies\n(but still fainter than L*) also display similar minor shifts in the N/O ratio.\nThe shifts in the average and median element abundance values in all absolute\nmagnitude bins studied are in the same direction, suggesting that the\nlarge-scale environment may influence the chemical evolution of galaxies. We\ndiscuss possible causes of such a large-scale environmental dependence of the\nchemical evolution of galaxies, including retarded star formation and a higher\ndark matter halo mass to stellar mass ratio in void galaxies.", "positive": "Globular clusters as probes of dark matter cusp-core transformations: Bursty star formation in dwarf galaxies can slowly transform a steep dark\nmatter cusp into a constant density core. We explore the possibility that\nglobular clusters (GCs) retain a dynamical memory of this transformation. To\ntest this, we use the nbody6df code to simulate the dynamical evolution of GCs,\nincluding stellar evolution, orbiting in static and time-varying potentials for\na Hubble time. We find that GCs orbiting within a cored dark matter halo, or\nwithin a halo that has undergone a cusp-core transformation, grow to a size\nthat is substantially larger ($R_{\\rm eff} > 10$ pc) than those in a static\ncusped dark matter halo. They also produce much less tidal debris. We find that\nthe cleanest signal of an historic cusp-core transformation is the presence of\nlarge GCs with tidal debris. However, the effect is small and will be\nchallenging to observe in real galaxies. Finally, we qualitatively compare our\nsimulated GCs with the observed GC populations in the Fornax, NGC 6822, IKN and\nSagittarius dwarf galaxies. We find that the GCs in these dwarf galaxies are\nsystematically larger ($\\langle R_{\\rm eff}\\rangle \\simeq 7.8$ pc), and have\nsubstantially more scatter in their sizes, than in-situ metal rich GCs in the\nMilky Way and young massive star clusters forming in M83 ($\\langle R_{\\rm eff}\n\\rangle \\simeq 2.5$ pc). We show that the size, scatter and survival of GCs in\ndwarf galaxies are all consistent with them having evolved in a constant\ndensity core, or a potential that has undergone a cusp-core transformation, but\nnot in a dark matter cusp." }, { "anchor": "Linking Ly-alpha and Low-Ionization Transitions at Low Optical Depth: We suggest that low optical depth in the Lyman continuum (LyC) may relate the\nLy-alpha emission, C II and Si II absorption, and C II* and Si II* emission\nseen in high-redshift galaxies. We base this analysis on Hubble Space Telescope\nCOS spectra of four Green Pea (GP) galaxies, which may be analogs of z>2\nLy-alpha emitters (LAEs). In the two GPs with the strongest Ly-alpha emission,\nthe Ly-alpha line profiles show reduced signs of resonant scattering. Instead,\nthe Ly-alpha profiles resemble the H-alpha line profiles of evolved star\nejecta, suggesting that the Ly-alpha emission originates from a low column\ndensity and similar outflow geometry. The weak C II absorption and presence of\nnon-resonant C II* emission in these GPs support this interpretation and imply\na low LyC optical depth along the line of sight. In two additional GPs, weak\nLy-alpha emission and strong C II absorption suggest a higher optical depth.\nThese two GPs differ in their Ly-alpha profile shapes and C II* emission\nstrengths, however, indicating different inclinations of the outflows to our\nline of sight. With these four GPs as examples, we explain the observed trends\nlinking Ly-alpha, C II, and C II* in stacked LAE spectra, in the context of\noptical depth and geometric effects. Specifically, in some galaxies with strong\nLy-alpha emission, a low LyC optical depth may allow Ly-alpha to escape with\nreduced scattering. Furthermore, C II absorption, C II* emission, and Ly-alpha\nprofile shape can reveal the optical depth, constrain the orientation of\nneutral outflows in LAEs, and identify candidate LyC emitters.", "positive": "Ghost of a Shell: Magnetic Fields of Galactic Supershell GSH\n 006$-$15$+$7: We identify a counterpart to a Galactic supershell in diffuse radio\npolarisation, and use this to determine the magnetic fields associated with\nthis object. GSH 006$-$15$+$7 has perturbed the polarised emission at\n2.3$\\,$GHz, as observed in the S-band Polarisation All Sky Survey (S-PASS),\nacting as a Faraday screen. We model the Faraday rotation over the shell, and\nproduce a map of Faraday depth over the area across it. Such models require\ninformation about the polarised emission behind the screen, which we obtain\nfrom the Wilkinson Microwave Anisotropy Probe (WMAP), scaled from 23$\\,$GHz to\n2.3$\\,$GHz, to estimate the synchrotron background behind GSH 006$-$15$+$7.\nUsing the modelled Faraday thickness we determine the magnitude and the\nplane-of-the-sky structure of the line-of-sight magnetic field in the shell. We\nfind a peak line-of-sight field strength of $|B_\\parallel|_\\text{peak} =\n2.0\\substack{+0.01 \\\\ -0.7}\\,\\mu$G. Our measurement probes weak magnetic fields\nin a low-density regime (number densities of $\\sim0.4\\,$cm$^{-3}$) of the ISM,\nthus providing crucial information about the magnetic fields in the\npartially-ionised phase." }, { "anchor": "Galactic Winds and the Role Played by Massive Stars: Galactic winds from star-forming galaxies play at key role in the evolution\nof galaxies and the inter-galactic medium. They transport metals out of\ngalaxies, chemically-enriching the inter-galactic medium and modifying the\nchemical evolution of galaxies. They affect the surrounding inter-stellar and\ncircum-galactic media, thereby influencing the growth of galaxies through gas\naccretion and star-formation. In this contribution we first summarize the\nphysical mechanisms by which the momentum and energy output from a population\nof massive stars and associated supernovae can drive galactic winds. We use the\nproto-typical example of M82 to illustrate the multiphase nature of galactic\nwinds. We then describe how the basic properties of galactic winds are derived\nfrom the data, and summarize how the properties of galactic winds vary\nsystematically with the properties of the galaxies that launch them. We\nconclude with a brief discussion of the broad implications of galactic winds.", "positive": "N$_2$H$^+$ and N$^{15}$NH$^+$ towards the prestellar core 16293E in\n L1689N: Understanding the processes that could lead to enrichment of molecules in\n$^{15}$N atoms is of particular interest in order to shed light on the\nrelatively large variations observed in the $^{14}$N/$^{15}$N ratio in various\nsolar system environments. Currently, the sample of molecular clouds where\n$^{14}$N/$^{15}$N ratios have been measured is small and has to be enlarged in\norder to allow statistically significant studies. In particular, the N$_2$H$^+$\nmolecule currently shows the largest spread of $^{14}$N/$^{15}$N ratios in\nhigh-mass star forming regions. However, the $^{14}$N/$^{15}$N ratio in\nN$_2$H$^+$ was obtained in only two low-mass star forming regions (L1544 and\nB1b). The current work extends this sample to a third dark cloud. We targeted\nthe 16293E prestellar core, where the N$^{15}$NH$^+$ $J$=1-0 line was detected.\nUsing a model previously developed for the physical structure of the source, we\nsolved the molecular excitation with a non-local radiative transfer code. For\nthat purpose, we computed specific collisional rate coefficients for the\nN$^{15}$NH$^+$-H$_2$ collisional system. As a first step of the analysis, the\nN$_2$H$^+$ abundance profile was constrained by reproducing the N$_2$H$^+$\n$J$=1-0 and 3-2 maps. A scaling factor was then applied to this profile to\nmatch the N$^{15}$NH$^+$ $J$=1-0 spectrum. We derive a column density ratio\nN$_2$H$^+$ / N$^{15}$NH$^+$ = $330^{+170}_{-100}$. The current estimate\n$\\sim$330 agrees with the value typical of the elemental isotopic ratio in the\nlocal ISM. It is however lower than in some other cores, where values as high\nas 1300 have been reported." }, { "anchor": "The lifecycle of molecular clouds in nearby star-forming disc galaxies: It remains a major challenge to derive a theory of cloud-scale ($\\lesssim100$\npc) star formation and feedback, describing how galaxies convert gas into stars\nas a function of the galactic environment. Progress has been hampered by a lack\nof robust empirical constraints on the giant molecular cloud (GMC) lifecycle.\nWe address this problem by systematically applying a new statistical method for\nmeasuring the evolutionary timeline of the GMC lifecycle, star formation, and\nfeedback to a sample of nine nearby disc galaxies, observed as part of the\nPHANGS-ALMA survey. We measure the spatially-resolved ($\\sim100$ pc)\nCO-to-H$\\alpha$ flux ratio and find a universal de-correlation between\nmolecular gas and young stars on GMC scales, allowing us to quantify the\nunderlying evolutionary timeline. GMC lifetimes are short, typically 10-30 Myr,\nand exhibit environmental variation, between and within galaxies. At kpc-scale\nmolecular gas surface densities $\\Sigma_{\\rm\nH_2}\\geqslant8$M$_{\\odot}$pc$^{-2}$, the GMC lifetime correlates with\ntime-scales for galactic dynamical processes, whereas at $\\Sigma_{\\rm\nH_2}\\leqslant8$M$_{\\odot}$pc$^{-2}$ GMCs decouple from galactic dynamics and\nlive for an internal dynamical time-scale. After a long inert phase without\nmassive star formation traced by H$\\alpha$ (75-90% of the cloud lifetime), GMCs\ndisperse within just 1-5 Myr once massive stars emerge. The dispersal is most\nlikely due to early stellar feedback, causing GMCs to achieve integrated star\nformation efficiencies of 4-10% These results show that galactic star formation\nis governed by cloud-scale, environmentally-dependent, dynamical processes\ndriving rapid evolutionary cycling. GMCs and HII regions are the fundamental\nunits undergoing these lifecycles, with mean separations of 100-300 pc in\nstar-forming discs. Future work should characterise the multi-scale physics and\nmass flows driving these lifecycles.", "positive": "Detection of molecular gas in an ALMA [CII]-identified Submillimetre\n Galaxy at z = 4.44: We present the detection of $^{12}$CO(2-1) in the $z = 4.44$ submillimetre\ngalaxy ALESS65.1 using the Australia Telescope Compact Array. A previous ALMA\nstudy of submillimetre galaxies in the Extended Chandra Deep Field South\ndetermined the redshift of this optically and near-infrared undetected source\nthrough the measurement of [CII] 157.74 $\\mu$m emission. Using the luminosity\nof the $^{12}$CO(2-1) emission we estimate the gas mass to be $M_{\\rm gas} \\sim\n1.7 \\times 10^{10}$ ${\\rm M}_\\odot$. The gas depletion timescale of ALESS65.1\nis $\\sim$ 25 Myr, similar to other high redshift submillimetre galaxies and\nconsistent with $z > 4$ SMGs being the progenitors of massive \"red-and-dead\"\ngalaxies at $z > 2$. The ratio of the [CII], $^{12}$CO and far-infrared\nluminosities implies a strong far-ultraviolet field of $G_0 \\sim 10^{3.25}$,\nwhich is at the high end of the far-ultraviolet fields seen in local\nstarbursts, but weaker than the far-ultraviolet fields of most nearby ULIRGs.\nThe high ratio of $L_{\\rm [CII]}/L_{\\rm FIR} = 1.0 \\times 10^{-3}$ observed in\nALESS65.1, combined with $L_{\\rm [CII]}/L_{\\rm CO} \\sim 2300$, is consistent\nwith ALESS65.1 having more extended regions of intense star formation than\nlocal ULIRGs." }, { "anchor": "Galactic-center S-Stars as a prospective test of the Einstein\n Equivalence Principle: The S-Stars in the Galactic-center region are found to be on near-perfect\nKeplerian orbits around presumably a supermassive black hole, with periods of\n15-50 yr. Since these stars reach a few percent of light speed at pericenter,\nvarious relativistic effects are expected, and have been discussed in the\nliterature. We argue that an elegant test of the Einstein equivalence principle\nshould be possible with existing instruments, through spectroscopic monitoring\nof an S-star concentrated during the months around pericenter, supplemented\nwith an already-adequate astrometric determination of the inclination. In\nessence, the spectrum of an S-star can be considered a heterogeneous ensemble\nof clocks in a freely-falling frame, which near pericenter is moving at\nrelativistic speeds.", "positive": "Mitigating Bias in Deep Learning: Training Unbiased Models on Biased\n Data for the Morphological Classification of Galaxies: Galaxy morphologies and their relation with physical properties have been a\nrelevant subject of study in the past. Most galaxy morphology catalogs have\nbeen labelled by human annotators or by machine learning models trained on\nhuman labelled data. Human generated labels have been shown to contain biases\nin terms of the observational properties of the data, such as image resolution.\nThese biases are independent of the annotators, that is, are present even in\ncatalogs labelled by experts. In this work, we demonstrate that training deep\nlearning models on biased galaxy data produce biased models, meaning that the\nbiases in the training data are transferred to the predictions of the new\nmodels. We also propose a method to train deep learning models that considers\nthis inherent labelling bias, to obtain a de-biased model even when training on\nbiased data. We show that models trained using our deep de-biasing method are\ncapable of reducing the bias of human labelled datasets." }, { "anchor": "Modeling chemistry during star formation: Water deuteration in dynamic\n star-forming regions: Recent observations of the HDO/H$_2$O ratio toward protostars in isolated and\nclustered environments show an apparent dichotomy, where isolated sources show\nhigher D/H ratios than clustered counterparts. Establishing which physical and\nchemical processes create this differentiation can provide insights into the\nchemical evolution of water during star formation and the chemical diversity\nduring the star formation process and in young planetary systems. Methods: The\nevolution of water is modeled using 3D physicochemical models of a dynamic\nstar-forming environment. The physical evolution during the protostellar\ncollapse is described by tracer particles from a 3D MHD simulation of a\nmolecular cloud region. Each particle trajectory is post-processed using\nRADMC-3D to calculate the temperature and radiation field. The chemical\nevolution is simulated using a three-phase grain-surface chemistry model and\nthe results are compared with interferometric observations of H$_2$O, HDO, and\nD$_2$O in hot corinos toward low-mass protostars. Results: The physicochemical\nmodel reproduces the observed HDO/H$_2$O and D$_2$O/HDO ratios in hot corinos,\nbut shows no correlation with cloud environment for similar identical\nconditions. The observed dichotomy in water D/H ratios requires variation in\nthe initial conditions (e.g., the duration and temperature of the prestellar\nphase). Reproducing the observed D/H ratios in hot corinos requires a\nprestellar phase duration $t\\sim$1-3 Myr and temperatures in the range $T \\sim$\n10-20 K prior to collapse. This work demonstrates that the observed\ndifferentiation between clustered and isolated protostars stems from\ndifferences in the molecular cloud or prestellar core conditions and does not\narise during the protostellar collapse itself.", "positive": "The SINS/zC-SINF Survey of z~2 Galaxy Kinematics: Rest-frame Morphology,\n Structure, and Colors from Near-infrared Hubble Space Telescope Imaging: We present the analysis of HST $J$- and $H$-band imaging for 29 galaxies on\nthe star-forming main sequence at $z\\sim2$, which have Adaptive Optics VLT\nSINFONI integral field spectroscopy from our SINS/zC-SINF program. The SINFONI\nH$\\alpha$ data resolve the on-going star-formation and the ionized gas\nkinematics on scales of $1-2$ kpc; the near-IR images trace the galaxies'\nrest-frame optical morphologies and distributions of stellar mass in old\nstellar populations at a similar resolution. The global light profiles of most\ngalaxies show disk-like properties well described by a single S\\'ersic profile\nwith $n\\sim1$, with only $\\sim15%$ requiring a high $n>3$ S\\'ersic index, all\nmore massive than $10^{10}M_\\odot$. In bulge+disk fits, about $40%$ of galaxies\nhave a measurable bulge component in the light profiles, with $\\sim15%$ showing\na substantial bulge-to-total ratio $B/T\\ge0.3$. This is a lower limit to the\nfrequency of $z\\sim2$ massive galaxies with a developed bulge component in\nstellar mass because it could be hidden by dust and/or outshined by a thick\nactively star-forming disk component. The galaxies' rest-optical half-light\nradii range between $1-7$ kpc, with a median of 2.1 kpc, and lie slightly above\nthe size-mass relation at these epochs reported in the literature. This is\nattributed to differences in sample selection and definitions of size and/or\nmass measurements. The $(u-g)_{rest}$ color gradient and scatter within\nindividual $z\\sim2$ massive galaxies with $\\ge10^{11}M_\\odot$ are as high as in\n$z=0$ low-mass, late-type galaxies, and are consistent with the high\nstar-formation rates of massive $z\\sim2$ galaxies being sustained at large\ngalactocentric distances." }, { "anchor": "Near-infrared spectroscopy in NGC 7538: The characterisation of the stellar population toward young high-mass\nstar-forming regions allows to constrain fundamental cluster properties like\ndistance and age. These are essential when using high-mass clusters as probes\nto conduct Galactic studies. NGC 7538 is a star-forming region with an embedded\nstellar population only unearthed in the near-infrared. We present the first\nnear-infrared spectro-photometric study of the candidate high-mass stellar\ncontent in NGC 7538. We obtained H and K spectra of 21 sources with both the\nmulti-object and long-slit modes of LIRIS at the WHT, and complement these data\nwith sub-arcsecond JHKs photometry of the region using the imaging mode of the\nsame instrument. We find a wide variety of objects within the studied stellar\npopulation of NGC 7538. Our results discriminate between a stellar population\nassociated to the HII region, but not contained within its extent, and several\npockets of more recent star formation. We report the detection of CO bandhead\nemission toward several sources as well as other features indicative of a young\nstellar nature. We infer a spectro-photometric distance of 2.7+-0.5 kpc, an age\nspread in the range 0.5-2.2 Myr and a total mass ~1.7x10^3 Msun for the older\npopulation.", "positive": "SimClust - A Program to Simulate Star Clusters: We present a program tool, SimClust, designed for Monte-Carlo modeling of\nstar clusters. It populates the available stellar isochrones with stars\naccording to the initial mass function and distributes stars randomly following\nthe analytical surface number density profile. The tool is aimed at simulating\nrealistic images of extragalactic star clusters and can be used to: (i)\noptimize object detection algorithms, (ii) perform artificial cluster tests for\nthe analysis of star cluster surveys, and (iii) assess the stochastic effects\nintroduced into photometric and structural parameters of clusters due to random\ndistribution of luminous stars and non-uniform interstellar extinction. By\napplying SimClust, we have demonstrated a significant influence of stochastic\neffects on the determined photometric and structural parameters of low-mass\nstar clusters in the M31 galaxy disk. The source code and examples are\navailable at the SimClust website: http://www.astro.ff.vu.lt/software/simclust/" }, { "anchor": "Nature versus nurture: relic nature and environment of the most massive\n passive galaxies at $z < 0.5$: Relic galaxies are thought to be the progenitors of high-redshift red nuggets\nthat for some reason missed the channels of size growth and evolved passively\nand undisturbed since the first star formation burst (at $z>2$). These local\nultracompact old galaxies are unique laboratories for studying the star\nformation processes at high redshift and thus the early stage of galaxy\nformation scenarios. Counterintuitively, theoretical and observational studies\nindicate that relics are more common in denser environments, where merging\nevents predominate. To verify this scenario, we compared the number counts of a\nsample of ultracompact massive galaxies (UCMGs) selected within the third data\nrelease of the Kilo Degree Survey, that is, systems with sizes $R_{\\rm e} < 1.5\n\\, \\rm kpc$ and stellar masses $M_{\\rm \\star} > 8 \\times 10^{10}\\, \\rm\nM_{\\odot}$, with the number counts of galaxies with the same masses but normal\nsizes in field and cluster environments. Based on their optical and\nnear-infrared colors, these UCMGs are likely to be mainly old, and hence\nrepresentative of the relic population. We find that both UCMGs and normal-size\ngalaxies are more abundant in clusters and their relative fraction depends only\nmildly on the global environment, with denser environments penalizing the\nsurvival of relics. Hence, UCMGs (and likely relics overall) are not special\nbecause of the environment effect on their nurture, but rather they are just a\nproduct of the stochasticity of the merging processes regardless of the global\nenvironment in which they live.", "positive": "The JADES Origins Field: A New JWST Deep Field in the JADES Second\n NIRCam Data Release: We summarize the properties and initial data release of the JADES Origins\nField (JOF), which will soon be the deepest imaging field yet observed with the\nJames Webb Space Telescope (JWST). This field falls within the GOODS-S region\nabout 8' south-west of the Hubble Ultra Deep Field (HUDF), where it was formed\ninitially in Cycle 1 as a parallel field of HUDF spectroscopic observations\nwithin the JWST Advanced Deep Extragalactic Survey (JADES). This imaging will\nbe greatly extended in Cycle 2 program 3215, which will observe the JOF for 5\ndays in six medium-band filters, seeking robust candidates for z>15 galaxies.\nThis program will also include ultra-deep parallel NIRSpec spectroscopy (up to\n104 hours on-source, summing over the dispersion modes) on the HUDF. Cycle 3\nobservations from program 4540 will add 20 hours of NIRCam slitless\nspectroscopy to the JOF. With these three campaigns, the JOF will be observed\nfor 380 open-shutter hours with NIRCam using 15 imaging filters and 2 grism\nbandpasses. Further, parts of the JOF have deep 43 hr MIRI observations in\nF770W. Taken together, the JOF will soon be one of the most compelling deep\nfields available with JWST and a powerful window into the early Universe. This\npaper presents the second data release from JADES, featuring the imaging and\ncatalogs from the year 1 JOF observations." }, { "anchor": "The miniJPAS survey: Maximising the photo-z accuracy from multi-survey\n datasets with probability conflation: We present a new method for obtaining photometric redshifts (photo-z) for\nsources observed by multiple photometric surveys using a combination\n(conflation) of the redshift probability distributions (PDZs) obtained\nindependently from each survey. The conflation of the PDZs has several\nadvantages over the usual method of modelling all the photometry together,\nincluding modularity, speed, and accuracy of the results. Using a sample of\ngalaxies with narrow-band photometry in 56 bands from J-PAS and deeper grizy\nphotometry from the Hyper-SuprimeCam Subaru Strategic program (HSC-SSP), we\nshow that PDZ conflation significantly improves photo-z accuracy compared to\nfitting all the photometry or using a weighted average of point estimates. The\nimprovement over J-PAS alone is particularly strong for i>22 sources, which\nhave low signal-to-noise ratio in the J-PAS bands. For the entire i<22.5\nsample, we obtain a 64% (45%) increase in the number of sources with redshift\nerrors |Dz|<0.003, a factor 3.3 (1.9) decrease in the normalised median\nabsolute deviation of the errors (sigma_NMAD), and a factor 3.2 (1.3) decrease\nin the outlier rate compared to J-PAS (HSC-SSP) alone. The photo-z accuracy\ngains from combining the PDZs of J-PAS with a deeper broadband survey such as\nHSC-SSP are equivalent to increasing the depth of J-PAS observations by\n~1.2--1.5 magnitudes. These results demonstrate the potential of PDZ conflation\nand highlight the importance of including the full PDZs in photo-z catalogues.", "positive": "Cool Subdwarf Investigations II: Multiplicity: Cool subdwarfs of types K and M are the fainter counterparts of cool main\nsequence dwarfs that dominate the Galactic population. In this paper we present\nthe results of an optical speckle survey of 62 confirmed cool subdwarf systems\nwithin 60 pc. We have resolved two new companions and confirmed two previously\nknown companions with separations 0\\farcs13 to 3\\farcs29. After including\npreviously known wide companions and all known spectroscopic binaries, we\ndetermine the multiplicity rate of cool subdwarfs to be 26$\\pm$6%, which is\nsomewhat lower than comparable main sequence stars, which have a multiplicity\nrate of 37$\\pm$5%. We find that only 3% of the cool subdwarfs surveyed have\ncompanions within 10 AU, 3% have companions between 10 and 100 AU, and 14% have\ncompanions beyond 100 AU. The other 6% of cool subdwarfs are spectroscopic\nbinaries. This is very different from K/M dwarfs that have most companions\n(13%) at separations closer than 10 AU. However, because a search for close\nbinaries among a large sample of nearby cool subdwarfs remains elusive, it is\nnot yet settled whether or not the multiplicity rates are significantly\ndifferent. Nonetheless, several different observational results and theories\npointing to a possible dearth of subdwarf multiples are discussed." }, { "anchor": "X-ray AGNs with SRG/eROSITA: Multi-wavelength observations reveal merger\n triggering and post-coalescence circumnuclear blowout: Major mergers between galaxies are predicted to fuel their central\nsupermassive black holes (SMBHs), particularly after coalescence. However,\ndetermining the prevalence of active galactic nuclei (AGNs) in mergers remains\na challenge, because AGN diagnostics are sensitive to details of the central\nstructure (e.g., nuclear gas clouds, geometry and orientation of a dusty torus)\nthat are partly decoupled from SMBH accretion. X-rays, expected to be\nubiquitous among accreting systems, are detectable through non-Compton-thick\nscreens of obscuring material, and thus offer the potential for a more complete\nassessment of AGNs in mergers. But, extant statistical X-ray studies of AGNs in\nmergers have been limited by either sparse, heterogeneous, or shallow on-sky\ncoverage. We use new X-ray observations from the first SRG/eROSITA all-sky data\nrelease to characterize the incidence, luminosity, and observability of AGNs in\nmergers. Combining machine learning and visual classification, we identify 923\npost-mergers in Dark Energy Camera Legacy Survey (DECaLS) imaging and select\n4,565 interacting galaxy pairs (with separations <120 kpc and mass ratios\nwithin 1:10) from the Sloan Digital Sky Survey. We find that galaxies with\nX-ray AGNs are 2.0+/-0.24 times as likely to be identified as post-mergers\ncompared to non-AGN controls, and that post-mergers are 1.8+/-0.1 times as\nlikely to host an X-ray AGN as non-interacting controls. A multi-wavelength\ncensus of X-ray, optical, and mid-IR-selected AGNs suggests a picture wherein\nthe underlying AGN fraction increases during pair-phase interactions, that\ngalaxy pairs within ~20 kpc become heavily obscured, and that the obscuration\noften clears post-coalescence.", "positive": "A New Stellar Mass Proxy for Subhalo Abundance Matching: Subhalo abundance matching (SHAM) has played an important role in improving\nour understanding of how galaxies populate their host dark matter halos. In\nessence, the SHAM framework is to find a dark matter halo property that best\ncorrelates with an attribute of galaxies, such as stellar mass. The peak value\nof the maximum circular velocity ($V_{\\rm max}$) a halo/subhalo has ever\nattained throughout its lifetime, $V_{\\rm peak}$, has been a popular choice for\nSHAM. A recent study by Tonnesen & Ostriker (2021) suggested that quantity\n$\\phi$, which combines the present-day $V_{\\rm max}$ and the peak value of halo\ndark matter mass, performs better in predicting stellar mass than $V_{\\rm\npeak}$. Inspired by their approach, in this work, we find that further\nimprovement can be achieved by a quantity $\\psi_5$ that combines the 90th\npercentile of $V_{\\rm max}$ a halo/subhalo has ever achieved with the 60th\npercentile of the dark matter halo time variation rate. Tests based on the\nsimulation IllustrisTNG300 show that our new SHAM scheme, with just three free\nparameters, can improve the stellar mass prediction and mass-dependent\nclustering by 15% and 16% from $\\phi$, respectively, over the redshift range\n$z=0-2$." }, { "anchor": "The Effects of Orbital Inclination on the Scale Size and Evolution of\n Tidally Filling Star Clusters: We have performed N-body simulations of tidally filling star clusters with a\nrange of orbits in a Milky Way-like potential to study the effects of orbital\ninclination and eccentricity on their structure and evolution. At small\ngalactocentric distances Rgc, a non-zero inclination results in increased mass\nloss rates. Tidal heating and disk shocking, the latter sometimes consisting of\ntwo shocking events as the cluster moves towards and away from the disk, help\nremove stars from the cluster. Clusters with inclined orbits at large Rgc have\ndecreased mass loss rates than the non-inclined case, since the strength the\ndisk potential decreases with Rgc. Clusters with inclined and eccentric orbits\nexperience increased tidal heating due to a constantly changing potential,\nweaker disk shocks since passages occur at higher Rgc, and an additional tidal\nshock at perigalacticon. The effects of orbital inclination decrease with\norbital eccentricity, as a highly eccentric cluster spends the majority of its\nlifetime at a large Rgc. The limiting radii of clusters with inclined orbits\nare best represented by the rt of the cluster when at its maximum height above\nthe disk, where the cluster spends the majority of its lifetime and the rate of\nchange in rt is a minimum. Conversely, the effective radius is independent of\ninclination in all cases.", "positive": "Global HI asymmetries in IllustrisTNG: a diversity of physical processes\n disturb the cold gas in galaxies: Observations of the cold neutral atomic hydrogen (HI) in and around disc\ngalaxies have revealed that spatial and kinematic asymmetries are commonplace,\nand are reflected in the global HI spectra. We use the TNG100 box from the\nIllustrisTNG suite of cosmological simulations to study the conditions under\nwhich these asymmetries may arise in current theoretical galaxy formation\nmodels. We find that more than 50% of the sample has at least a 10% difference\nin integrated flux between the high- and low-velocity half of the spectrum,\nthus the typical TNG100 galaxy has an HI profile that is not fully symmetric.\nWe find that satellite galaxies are a more asymmetric population than centrals,\nconsistent with observational results. Using halo mass as a proxy for\nenvironment, this trend appears to be driven by the satellite population within\nthe virial radius of haloes more massive than $10^{13} M_{\\odot}$, typical of\nmedium/large groups. We show that, while the excess of HI asymmetry in group\nsatellites is likely driven by ram pressure, the bulk of the asymmetric HI\nprofiles observed in TNG100 are driven by physical processes able to affect\nboth the central and satellite populations. Our results highlight how\nasymmetries are not driven solely by environment, and multiple physical\nprocesses can produce the same asymmetric shape in global HI spectra." }, { "anchor": "Galactic rotation in Gaia DR1: The spatial variations of the velocity field of local stars provide direct\nevidence of Galactic differential rotation. The local divergence, shear, and\nvorticity of the velocity field---the traditional Oort constants---can be\nmeasured based purely on astrometric measurements and in particular depend\nlinearly on proper motion and parallax. I use data for 304,267 main-sequence\nstars from the Gaia DR1 Tycho-Gaia Astrometric Solution to perform a local,\nprecise measurement of the Oort constants at a typical heliocentric distance of\n230 pc. The pattern of proper motions for these stars clearly displays the\nexpected effects from differential rotation. I measure the Oort constants to\nbe: A = 15.3+/-0.4 km/s/kpc, B = -11.9+/-0.4 km/s/kpc, C = -3.2+/-0.4 km/s/kpc\nand K = -3.3+/-0.6 km/s/kpc, with no color trend over a wide range of stellar\npopulations. These first confident measurements of C and K clearly demonstrate\nthe importance of non-axisymmetry for the velocity field of local stars and\nthey provide strong constraints on non-axisymmetric models of the Milky Way.", "positive": "Infrared photometry and CaT spectroscopy of globular cluster M 28 (NGC\n 6626): Recent studies show that the inner Galactic regions host genuine bulge\nglobular clusters, but also halo intruders, complex remnants of primordial\nbuilding blocks, and objects likely accreted during major merging events. In\nthis study we focus on the properties of M 28, a very old and massive cluster\ncurrently located in the Galactic bulge. We analysed wide-field infrared\nphotometry collected by the VVV survey, VVV proper motions, and\nintermediate-resolution spectra in the calcium triplet range for 113 targets in\nthe cluster area. Our results in general confirm previous estimates of the\ncluster properties available in the literature. We find no evidence of\ndifferences in metallicity between cluster stars, setting an upper limit of\nDelta[Fe/H]<0.08 dex to any internal inhomogeneity. We confirm that M 28 is one\nof the oldest objects in the Galactic bulge (13-14 Gyr). From this result and\nthe literature data, we find evidence of a weak age-metallicity relation among\nbulge globular clusters that suggests formation and chemical enrichment. In\naddition, wide-field density maps show that M 28 is tidally stressed and that\nit is losing mass into the general bulge field. Our study indicates that M 28\nis a genuine bulge globular cluster, but its very old age and its mass loss\nsuggest that this cluster could be the remnant of a larger structure, possibly\na primeval bulge building block." }, { "anchor": "Strategies for optimal sky subtraction in the low surface brightness\n regime: The low surface brightness (LSB) regime ($\\mu_{g} \\gtrsim 26$ mag\narcsec$^{-2}$) comprises a vast, mostly unexplored discovery space, from dwarf\ngalaxies to the diffuse interstellar medium. Accessing this regime requires\nprecisely removing instrumental signatures and light contamination, including,\nmost critically, night sky emission. This is not trivial, as faint\nastrophysical and instrumental contamination can bias sky models at the\nprecision needed to characterize LSB structures. Using idealized synthetic\nimages, we assess how this bias impacts two common LSB-oriented sky-estimation\nalgorithms: 1.) masking and parametric modelling, and 2.) stacking and\nsmoothing dithered exposures. Undetected flux limits both methods by imposing a\npedestal offset to all derived sky models. Careful, deep masking of fixed\nsources can mitigate this, but source density always imposes a fundamental\nlimit. Stellar scattered light can contribute $\\sim28$--$29$ mag arcsec$^{-2}$\nof background flux even in low-density fields; its removal is critical prior to\nsky estimation. For complex skies, image combining is an effective\nnon-parametric approach, although it strongly depends on observing strategy and\nadds noise to images on the smoothing kernel scale. Preemptive subtraction of\nfixed sources may be the only practical approach for robust sky estimation. We\nthus tested a third algorithm, subtracting a preliminary sky-subtracted coadd\nfrom exposures to isolate sky emission. Unfortunately, initial errors in sky\nestimation propagate through all subsequent sky models, making the method\nimpractical. For large-scale surveys like LSST, where key science goals\nconstrain observing strategy, masking and modelling remains the optimal sky\nestimation approach, assuming stellar scattered light is removed first.", "positive": "Millimeter wave spectrum and search for vinyl isocyanate toward Sgr\n B2(N) with ALMA: The interstellar detections of isocyanic acid, methyl isocyanate, and very\nrecently also ethyl isocyanate, open the question of the possible detection of\nvinyl isocyanate in the interstellar medium. The aim of this study is to extend\nthe laboratory rotational spectrum of vinyl isocyanate into the millimeter wave\nregion and to undertake a check for its presence in the high-mass star forming\nregion Sgr B2. The rotational spectrum of vinyl isocyanate was recorded in the\nfrequency regions 127.5-218 and 285-330 GHz using the Prague millimeter wave\nspectrometer. The spectral analysis was supported by high-level\nquantum-chemical calculations. We assumed local thermodynamic equilibrium to\ncompute synthetic spectra of vinyl isocyanate and to search for it in the\nReMoCA survey performed with ALMA toward Sgr B2(N). We also searched for ethyl\nisocyanate in the same source. Accurate values for the rotational and\ncentrifugal distortion constants are reported for the ground vibrational states\nof trans and cis vinyl isocyanate. We report nondetections of vinyl and ethyl\nisocyanate toward the main hot core of Sgr B2(N). We find that vinyl and ethyl\nisocyanate are at least 11 and 3 times less abundant than methyl isocyanate in\nthis source, respectively. Although the precise formation mechanism of\ninterstellar methyl isocyanate itself remains uncertain, we infer from existing\nastrochemical models that our observational upper limit for the CH3NCO:C2H5NCO\nratio in Sgr B2(N) is consistent with ethyl isocyanate being formed on dust\ngrains via the abstraction or photodissociation of an H atom from methyl\nisocyanate, followed by the addition of a methyl radical. The dominance of such\na process for ethyl isocyanate production, combined with the absence of an\nanalogous mechanism for vinyl isocyanate, would indicate that the ratio\nC2H3NCO:C2H5NCO should be rather less than unity." }, { "anchor": "The Vista Variables in the Via Lactea (VVV) ESO Public Survey: Current\n Status and First Results: Vista Variables in the Via Lactea (VVV) is an ESO Public Survey that is\nperforming a variability survey of the Galactic bulge and part of the inner\ndisk using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA).\nThe survey covers 520 deg^2 of sky area in the ZYJHK_S filters, for a total\nobserving time of 1929 hours, including ~ 10^9 point sources and an estimated ~\n10^6 variable stars. Here we describe the current status of the VVV Survey, in\naddition to a variety of new results based on VVV data, including light curves\nfor variable stars, newly discovered globular clusters, open clusters, and\nassociations. A set of reddening-free indices based on the ZYJHK_S system is\nalso introduced. Finally, we provide an overview of the VVV Templates Project,\nwhose main goal is to derive well-defined light curve templates in the near-IR,\nfor the automated classification of VVV light curves.", "positive": "Metal Enrichment in the Reionization Epoch: The presence of elements heavier than helium (\"metals\") is of fundamental\nimportance for a large number of astrophysical processes occurring in planet,\nstar and galaxy formation; it also affects cosmic structure formation and\nevolution in several ways. Even a small amount of heavy elements can\ndramatically alter the chemistry of the gas, opening the path to complex\nmolecules. Metals might enhance the ability of the gas to radiate away its\nthermal energy, thus favoring the formation of gravitationally bound objects;\nthey can also condensate in a solid phase (dust grains), partly or totally\nblocking radiation from luminous sources. Finally, they represent useful\ntracers of energy deposition by stars and probe the physical properties of the\nenvironment by absorption or emission lines. Last, but certainly not least,\nlife -- as we know it on Earth -- is tightly related to the presence of at\nleast some of the heavy elements. In this pedagogical review I will concentrate\non the connection between early metal enrichment and cosmic reionization. As we\nwill see these two processes are intimately connected and their joint study\nmight turn out to be fundamental in understanding the overall evolution of the\nUniverse during the first billion years after the Big Bang, an epoch\ncorresponding to redshifts z>6." }, { "anchor": "Radio Continuum Sources behind the Large Magellanic Cloud: We present a comprehensive multi-frequency catalogue of radio sources behind\nthe Large Magellanic Cloud between 0.2 and 20 GHz, gathered from a combination\nof new and legacy radio continuum surveys. This catalogue covers an area of\n$\\sim$144~deg$^2$ at angular resolutions from 45 arcsec to $\\sim$3 arcmin. We\nfind 6434 discrete radio sources in total, of which 3789 are detected at two or\nmore radio frequencies. We estimate the median spectral index ($\\alpha$; where\n$S_{v}\\sim\\nu^\\alpha$) of $\\alpha = -0.89 $ and mean of $-0.88 \\pm 0.48$ for\n3636 sources detected exclusively at two frequencies (0.843 and 1.384 GHz) with\nsimilar resolution (FWHM $\\sim$40-45 arcsec). The large frequency range of the\nsurveys makes it an effective tool to investigate Gigahertz Peak Spectrum\n(GPS), Compact Steep Spectrum (CSS) and Infrared Faint Radio sources\npopulations within our sample. We find 10 GPS candidates with peak frequencies\nnear 5 GHz, from which we estimate their linear size. 1866 sources from our\ncatalogue are (CSS) candidates with $\\alpha <-0.8$. We found six candidates for\nHigh Frequency Peaker (HFP) sources, whose radio fluxes peak above 5 GHz and no\nsources with unconstrained peaks and $\\alpha~>0.5$. We found optical\ncounterparts for 343 of the radio continuum sources, of which 128have a\nredshift measurement. Finally, we investigate the population of 123 Infrared\nFaint Radio Sources (IFRSs) found in this study.", "positive": "What can Gaia (with TMT) say about Sculptor's Core?: Walker et al.'s Magellan/MMFS Survey survey identified 1355 red giant\ncandidates in the dwarf spheroidal galaxy Sculptor. We find that the Gaia\nsatellite will be able to measure the proper motions of 139 of these with a\nprecision of between 13 and 20 km/s. Using a Jeans analysis and 5-parameter\ndensity model we show that this allows a determination of the mass within the\ndeprojected half-light radius to within 16% and a measurement of the dark\nmatter density exponent gamma to within 0.68 within that radius. If, even at\nfirst light, the TMT observes Sculptor then the combined observations will\nimprove the precision on these proper motions to about 5 km/s, about 5 years\nearlier than would be possible without Gaia, further improving the precision of\ngamma to 0.27. Using a bimodal stellar population model for Sculptor the\nprecision of gamma improves by about 30%. This suggests that Gaia (with TMT) is\ncapable of excluding a cored profile of the kind predicted by CDM simulations\nwith 2 sigma (4 sigma) of confidence." }, { "anchor": "Simple MCBR models of chemical evolution: an application to the thin and\n the thick disk: Simple MCBR models of chemical evolution are extended to the limit of\ndominant gas inflow or outflow with respect to gas locked up into long-lived\nstars and remnants. For an assigned empirical differential oxygen abundance\ndistribution, which can be linearly fitted, a family of theoretical curves is\nbuilt up with assigned prescriptions. For curves with increasing cut parameter,\nthe gas mass fraction locked up into long-lived stars and remnants is found to\nattain a maximum and then decrease towards zero as the flow tends to infinity,\nwhile the remaining parameters show a monotonic trend. The theoretical integral\noxygen abundance distribution is also expressed. An application is performed to\nthe empirical distribution deduced from two different samples of disk stars,\nfor both the thin and the thick disk. The constraints on formation and\nevolution are discussed in the light of the model. The evolution is tentatively\nsubdivided into four stages, A, F, C, E. The empirical distribution related to\nany stage is fitted by all curves for a wide range of the cut parameter. The F\nstage may safely be described by a steady inflow regime, implying a flat\ntheoretical distribution, in agreement with the results of hydrodynamical\nsimulations. Finally, (1) the change of fractional mass due to the extension of\nthe linear fit to the empirical distribution, towards both the (undetected)\nlow-metallicity and high-metallicity tail, is evaluated and (2) the idea of a\nthick disk-thin disk collapse is discussed, in the light of the model.", "positive": "FRAMEx II: Simultaneous X-ray and Radio Variability in Active Galactic\n Nuclei $-$ The Case of NGC 2992: Using simultaneous Very Long Baseline Array and Neil Gehrels Swift\nObservatory X-ray Telescope observations of the active galactic nucleus (AGN)\nin NGC 2992 over a six-month observing campaign, we observed a large drop in\ncore 5 cm radio luminosity, by a factor of $>3$, in tandem with factor of $>5$\nincrease in $2-10$ keV X-ray luminosity. While NGC 2992 has long been an\nimportant object for studies of X-ray variability, our study is the first\nsimultaneous X-ray and radio variability campaign on this object. We observe\nthat the X-ray spectral index does not change over the course of the flare,\nconsistent with a change in the bulk amount of Comptonizing plasma, potentially\ndue to a magnetic reconnection event in the accretion disk. The drop in\napparent radio luminosity can be explained by a change in free-free absorption,\nwhich we calculate to correspond to an ionized region with physical extent and\nelectron density consistent with the broad line region (BLR). Our results are\nconsistent with magnetic reconnection events in the dynamic accretion disk\ncreating outbursts of ionizing material, increasing Compton up-scattering of UV\naccretion disk photons and feeding material into the BLR. These findings\npresent an important physical picture for the dynamical relationship between\nX-ray and radio emission in AGNs." }, { "anchor": "Detection of Extremely Broad Water Emission from the molecular cloud\n interacting Supernova Remnant G349.7+0.2: We performed Herschel HIFI, PACS and SPIRE observations towards the molecular\ncloud interacting supernova remnant G349.7+0.2. An extremely broad emission\nline was detected at 557 GHz from the ground state transition 1_{10}-1_{01} of\northo-water. This water line can be separated into three velocity components\nwith widths of 144, 27 and 4 km/s. The 144 km/s component is the broadest water\nline detected to date in the literature. This extremely broad line width shows\nimportance of probing shock dynamics. PACS observations revealed 3 additional\northo-water lines, as well as numerous high-J carbon monoxide (CO) lines. No\npara-water lines were detected. The extremely broad water line is indicative of\na high velocity shock, which is supported by the observed CO rotational diagram\nthat was reproduced with a J-shock model with a density of 10^4 cm^{-3} and a\nshock velocity of 80 km/s. Two far-infrared fine-structure lines, [O~I] at 145\nmicron and [C~II] line at 157 micron, are also consistent with the high\nvelocity J-shock model. The extremely broad water line could be simply from\nshort-lived molecules that have not been destroyed in high velocity J-shocks;\nhowever, it may be from more complicated geometry such as high-velocity water\nbullets or a shell expanding in high velocity. We estimate the CO and H2O\ndensities, column densities, and temperatures by comparison with RADEX and\ndetailed shock models. Detection of Extremely Broad Water Emission from the\nmolecular cloud interacting Supernova Remnant G349.7+0.2", "positive": "Investigating the Effect of Galaxy Interactions on Star Formation at\n 0.510^{10}M_\\odot$) major\n($1 10.6$) per cluster\nand average sSFR rise significantly with redshift. For CO detections, we find\n$f_{gas} \\sim 0.2$, comparable to those of field galaxies, and gas depletion\ntimescales of about 2 Gyr. We use radio observations to distinguish active\ngalactic nuclei (AGNs) from star-forming galaxies. At least four of our 19\nHerschel cluster members have $q_{IR} < 1.8$, implying an AGN fraction $f_{AGN}\n\\gtrsim 0.2$ for our PACS-selected sample.", "positive": "The early growth of supermassive black holes in cosmological\n hydrodynamic simulations with constrained Gaussian realizations: The paper examines the early growth of supermassive black holes (SMBHs) in\ncosmological hydrodynamic simulations with different BH seeding scenarios.\nEmploying the constrained Gaussian realization, we reconstruct the initial\nconditions in the large-volume BlueTides simulation and run them to $z=6$ to\ncross-validate that the method reproduces the first quasars and their\nenvironments. Our constrained simulations in a volume of $(15\\, h^{-1}{\\rm\nMpc})^3$ successfully recover the evolution of large-scale structure and the\nstellar and BH masses in the vicinity of a $\\sim10^{12}\\, M_{\\odot}$ halo which\nwe identified in BlueTides at $z\\sim7$ hosting a $\\sim10^9\\, M_{\\odot}$ SMBH.\nAmong our constrained simulations, only the ones with a low-tidal field and\nhigh-density peak in the initial conditions induce the fastest BH growth\nrequired to explain the $z>6$ quasars. We run two sets of simulations with\ndifferent BH seed masses of $5\\times10^3$, $5\\times10^4$, and $5\\times10^5\\,\nh^{-1}M_{\\odot}$, (a) with the same ratio of halo to BH seed mass and (b) with\nthe same halo threshold mass. At $z=6$, all the SMBHs converge in mass to\n$\\sim10^9\\, M_{\\odot}$ except for the one with the smallest seed in (b)\nundergoing critical BH growth and reaching $10^8$ -- $10^9\\, M_{\\odot}$, albeit\nwith most of the growth in (b) delayed compared to set (a). The finding of\neight BH mergers in the small-seed scenario (four with masses $10^4$ -- $10^6\\,\nM_{\\odot}$ at $z>12$), six in the intermediate-seed scenario, and zero in the\nlarge-seed scenario suggests that the vast BHs in the small-seed scenario merge\nfrequently during the early phases of the growth of SMBHs. The increased BH\nmerger rate for the low-mass BH seed and halo threshold scenario provides an\nexciting prospect for discriminating BH formation mechanisms with the advent of\nmulti-messenger astrophysics and next-generation gravitational wave facilities." }, { "anchor": "GNOMES II: Analysis of the Galactic diffuse molecular ISM in all four\n ground state hydroxyl transitions using Amoeba: We present observations of the four 2 Pi 3/2 J = 3/2 ground-rotational state\ntransitions of the hydroxyl molecule (OH) along 107 lines of sight both in and\nout of the Galactic plane: 92 sets of observations from the Arecibo telescope\nand 15 sets of observations from the Australia Telescope Compact Array (ATCA).\nOur Arecibo observations included off-source pointings, allowing us to measure\nexcitation temperature (Tex) and optical depth, while our ATCA observations\ngive optical depth only. We perform Gaussian decomposition using the Automated\nMolecular Excitation Bayesian line-fitting Algorithm 'AMOEBA' (Petzler, Dawson,\nand Wardle 2021) fitting all four transitions simultaneously with shared\ncentroid velocity and width. We identify 109 features across 38 sightlines\n(including 58 detections along 27 sightlines with excitation temperature\nmeasurements). While the main lines at 1665 and 1667 MHz tend to have similar\nexcitation temperatures (median Tex(main) difference = 0.6 K, 84% show\nTex(main) difference < 2 K), large differences in the 1612 and 1720 MHz\nsatellite line excitation temperatures show that the gas is generally not in\nLTE. For a selection of sightlines we compare our OH features to associated\n(on-sky and in velocity) HI cold gas components (CNM) identified by Nguyen et\nal. (2019) and find no strong correlations. We speculate that this may indicate\nan effective decoupling of the molecular gas from the CNM once it accumulates.", "positive": "The OGLE View of Microlensing towards the Magellanic Clouds. I. A\n Trickle of Events in the OGLE-II LMC data: We present the results from the OGLE-II survey (1996-2000) towards the Large\nMagellanic Cloud (LMC), which has the aim of detecting the microlensing\nphenomena caused by dark matter compact objects in the Galactic Halo (Machos).\n We use high resolution HST images of the OGLE fields and derive the\ncorrection for the number of monitored stars in each field. This also yield\nblending distributions which we use in 'catalogue level' Monte Carlo\nsimulations of the microlensing events in order to calculate the detection\nefficiency of the events.\n We detect two candidates for microlensing events in the All Stars Sample,\nwhich translates into an optical depth of 0.43+-0.33x 10e-7. If both events\nwere due to Macho the fraction of mass of compact dark matter objects in the\nGalactic halo would be 8+-6 per cent. This optical depth, however, along with\nthe characteristics of the events, seems to be consistent with the self-lensing\nscenario, i.e., self-lensing alone is sufficient to explain the observed\nmicrolensing signal. Our results indicate a non-detection of Machos lensing\ntowards the LMC with an upper limit on their abundance in the Galactic halo of\n19 per cent for M=0.4 Msun and 10 per cent for masses between 0.01 and 0.2\nMsun." }, { "anchor": "The AGORA High-Resolution Galaxy Simulations Comparison Project: We introduce the AGORA project, a comprehensive numerical study of\nwell-resolved galaxies within the LCDM cosmology. Cosmological hydrodynamic\nsimulations with force resolutions of ~100 proper pc or better will be run with\na variety of code platforms to follow the hierarchical growth, star formation\nhistory, morphological transformation, and the cycle of baryons in and out of 8\ngalaxies with halo masses M_vir ~= 1e10, 1e11, 1e12, and 1e13 Msun at z=0 and\ntwo different (\"violent\" and \"quiescent\") assembly histories. The numerical\ntechniques and implementations used in this project include the smoothed\nparticle hydrodynamics codes GADGET and GASOLINE, and the adaptive mesh\nrefinement codes ART, ENZO, and RAMSES. The codes will share common initial\nconditions and common astrophysics packages including UV background,\nmetal-dependent radiative cooling, metal and energy yields of supernovae, and\nstellar initial mass function. These are described in detail in the present\npaper. Subgrid star formation and feedback prescriptions will be tuned to\nprovide a realistic interstellar and circumgalactic medium using a\nnon-cosmological disk galaxy simulation. Cosmological runs will be\nsystematically compared with each other using a common analysis toolkit, and\nvalidated against observations to verify that the solutions are robust - i.e.,\nthat the astrophysical assumptions are responsible for any success, rather than\nartifacts of particular implementations. The goals of the AGORA project are,\nbroadly speaking, to raise the realism and predictive power of galaxy\nsimulations and the understanding of the feedback processes that regulate\ngalaxy \"metabolism.\" The proof-of-concept dark matter-only test of the\nformation of a galactic halo with a z=0 mass of M_vir ~= 1.7e11 Msun by 9\ndifferent versions of the participating codes is also presented to validate the\ninfrastructure of the project.", "positive": "The faint end of the Centaurus A satellite luminosity function: The Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) is\nconstructing a wide-field map of the resolved stellar populations in the\nextended halos of these two nearby, prominent galaxies. We present new\nMagellan/Megacam imaging of a $\\sim3$ deg$^2$ area around Centaurus A (Cen A),\nwhich filled in much of our coverage to its south, leaving a nearly complete\nhalo map out to a projected radius of $\\sim$150 kpc and allowing us to identify\ntwo new resolved dwarf galaxies. We have additionally obtained deep Hubble\nSpace Telescope (HST) optical imaging of eleven out of the thirteen candidate\ndwarf galaxies identified around Cen A and presented in Crnojevi\\'c et al.\n(2016): seven are confirmed to be satellites of Cen A, while four are found to\nbe background galaxies. We derive accurate distances, structural parameters,\nluminosities and photometric metallicities for the seven candidates confirmed\nby our HST/ACS imaging. We further study the stellar population along the\n$\\sim$60 kpc long (in projection) stream associated with Dw3, which likely had\nan initial brightness of $M_{V}$$\\sim$$-$15 and shows evidence for a\nmetallicity gradient along its length. Using the total sample of eleven dwarf\nsatellites discovered by the PISCeS survey, as well as thirteen brighter\npreviously known satellites of Cen A, we present a revised galaxy luminosity\nfunction for the Cen A group down to a limiting magnitude of $M_V\\sim-8$, which\nhas a slope of $-1.14\\pm0.17$, comparable to that seen in the Local Group and\nin other nearby groups of galaxies." }, { "anchor": "A closer view of the radio-FIR correlation: disentangling the\n contributions of star formation and AGN activity: We extend the Unified Radio Catalog, a catalog of sources detected by various\n(NVSS, FIRST, WENSS, GB6) radio surveys, and SDSS, to IR wavelengths by\nmatching it to the IRAS Point and Faint Source catalogs. By fitting each\nNVSS-selected galaxy's NUV-NIR spectral energy distribution (SED) with stellar\npopulation synthesis models we add to the catalog star formation rates, stellar\nmasses, and attenuations.We further add information about optical emission line\nproperties for NVSS-selected galaxies with available SDSS spectroscopy. Using\nan NVSS 20cm (F_{1.4GHz} ge 2.5mJy) selected sample, matched to the SDSS\nspectroscopic (\"main\" galaxy and quasar) catalogs and IRAS data (0.04100 km/s) absorption feature. Around 70-75% of the gas mass,\nconcentrated in just the 27% densest molecular clumps, is associated with\nrotating structures and show evidences of association with each of the arcs of\nionized gas in the mini-spiral structure. Chemical differentiation has been\nproven to be a powerful tool to disentangle the many overlapping molecular\ncomponents in this crowded and heavily obscured region.", "positive": "First Sub-pc Sale Mapping of Magnetic Fields in the Vicinity of a Very\n Low Luminosity Object, L1521F-IRS: L1521F is found to be forming multiple cores and it is cited as an example of\nthe densest core with an embedded VeLLO in a highly dynamical environment. We\npresent the core-scale magnetic fields (B-fields) in the near vicinity of the\nVeLLO L1521F-IRS using submm polarization measurements at 850$~\\mu$m using JCMT\nPOL-2. This is the first attempt to use high-sensitivity observations to map\nthe sub-parsec scale B-fields in a core with a VeLLO. The B-fields are ordered\nand very well connected to the parsec-scale field geometry seen in our earlier\noptical polarization observations and the large-scale structure seen in Planck\ndust polarization. The core scale B-field strength estimated using\nDavis-Chandrasekhar-Fermi relation is $\\rm 330\\pm100~\\mu$G which is more than\nten times of the value we obtained in the envelope (envelope in this paper is\n\"core envelope\"). This indicates that B-fields are getting stronger on smaller\nscales. The magnetic energies are found to be 1 to 2 orders of magnitude higher\nthan non-thermal kinetic energies in the envelope and core. This suggests that\nmagnetic fields are more important than turbulence in the energy budget of\nL1521F. The mass-to-flux ratio of 2.3$\\pm$0.7 suggests that the core is\nmagnetically-supercritical. The degree of polarization is steadily decreasing\ntowards the denser part of the core with a power law slope of -0.86." }, { "anchor": "New Near-Infrared Imaging and Spectroscopy of NGC 2071-IR: We present high resolution images of NGC 2071-IR in the $J$, $H$, and $K$\nbands and in the emission at 2.12 $\\mu$m of the v=$1-0$ $S$(1) line of\nmolecular hydrogen. We also present moderate resolution K-band spectra of two\nyoung stellar objects, IRS 1 and IRS 3, within NGC 2071-IR, that are candidates\nsources of one or more of the outflows observed in the region. Two of the eight\noriginally identified infrared point sources in NGC 2071-IR are binaries, and\nwe identifiy two new sources, one coincident with the radio source VLA-1 and\nhighly reddened. The H2 $Q$(3)/$S$(1) line intensity ratios at IRS 1 and IRS 3\nyield high and very high extinctions, respectively, to them, as is implied by\ntheir near-infrared colors and K-band continuum slopes. The spectra also reveal\nthe presence of hot, dense circumstellar molecular gas in each, suggesting that\nboth are strong candidates for having energetic molecular outflows. We agree\nwith a previous suggestion that IRS 1 is the likely source of an E-W-oriented\noutflow and conclude that this outflow is probably largely out of the plane of\nthe sky. We also conclude that if IRS 3 is the source of the large scale NE-SW\noutflow, as has been previously suggested, its jet/wind must precess in order\nto explain the angular width of that outflow. We discuss the natures of the\npoint sources and their probable contributions, if any, to the complex\nmorphology of the H2 line emission.", "positive": "Quantifying kinematic substructure in star-forming regions with\n statistical tests of spatial autocorrelation: We investigate whether spatial-kinematic substructure in young star-forming\nregions can be quantified using Moran's $I$ statistic. Its presence in young\nstar clusters would provide an indication that the system formed from initially\nsubstructured conditions, as expected by the hierarchical model of star cluster\nformation, even if the cluster were spatially smooth and centrally\nconcentrated. Its absence, on the other hand, would be evidence that star\nclusters form monolithically. The Moran's $I$ statistic is applied to $N$-body\nsimulations of star clusters with different primordial spatial-velocity\nstructures, and its evolution over time is studied. It is found that this\nstatistic can be used to reliably quantify spatial-kinematic substructure, and\ncan be used to provide evidence as to whether the spatial-kinematic structure\nof regions with ages $\\lesssim$ 6 Myr is best reproduced by the hierarchical or\nmonolithic models of star formation. Moran's $I$ statistic is also able to\nconclusively say whether the data are $not$ consistent with initial conditions\nthat lack kinematic substructure, such as the monolithic model, in regions with\nages up to, and potentially beyond, 10 Myrs. This can therefore provide a\nkinematic signature of the star cluster formation process that is observable\nfor many Myr after any initial spatial structure has been erased." }, { "anchor": "The Panchromatic Hubble Andromeda Treasury. VI. The reliability of\n far-ultraviolet flux as a star formation tracer on sub-kpc scales: We have used optical observations of resolved stars from the Panchromatic\nHubble Andromeda Treasury (PHAT) to measure the recent (< 500 Myr) star\nformation histories (SFHs) of 33 FUV-bright regions in M31. The region areas\nranged from ~$10^4$ to $10^6$ pc$^2$, which allowed us to test the reliability\nof FUV flux as a tracer of recent star formation on sub-kpc scales. The star\nformation rates (SFRs) derived from the extinction-corrected observed FUV\nfluxes were, on average, consistent with the 100-Myr mean SFRs of the SFHs to\nwithin the 1$\\sigma$ scatter. Overall, the scatter was larger than the\nuncertainties in the SFRs and particularly evident among the smallest regions.\nThe scatter was consistent with an even combination of discrete sampling of the\ninitial mass function and high variability in the SFHs. This result\ndemonstrates the importance of satisfying both the full-IMF and the\nconstant-SFR assumptions for obtaining precise SFR estimates from FUV flux.\nAssuming a robust FUV extinction correction, we estimate that a factor of 2.5\nuncertainty can be expected in FUV-based SFRs for regions smaller than $10^5$\npc$^2$, or a few hundred pc. We also examined ages and masses derived from UV\nflux under the common assumption that the regions are simple stellar\npopulations (SSPs). The SFHs showed that most of the regions are not SSPs, and\nthe age and mass estimates were correspondingly discrepant from the SFHs. For\nthose regions with SSP-like SFHs, we found mean discrepancies of 10 Myr in age\nand a factor of 3 to 4 in mass. It was not possible to distinguish the SSP-like\nregions from the others based on integrated FUV flux.", "positive": "Subhalo abundance and satellite spatial distribution in Milky\n Way-Andromeda-like paired haloes: We study the subhalo and satellite populations in haloes similar to the Milky\nWay (MW)-Andromeda paired configuration in the Millennium II and P-Millennium\nsimulations. We find subhaloes are $5\\%-15\\%$ more abundant in paired haloes\nthan their isolated counterparts that have the same halo mass and large-scale\nenvironmental density. Paired haloes tend to reside in a more isotropic\nenvironment than isolated haloes, the shear tensor of their large-scale tidal\nfield is possibly responsible for this difference. We also study the thickness\nof the spatial distribution of the top 11 most massive satellite galaxies\nobtained in the semi-analytic galaxy sample constructed from the Millennium II\nsimulation. Moreover, satellites that have lost their host subhaloes due to the\nresolution limit of the simulation have been taken into account. As a result,\nwe find that the difference in the distribution of the satellite thickness\nbetween isolated and paired haloes is indistinguishable, which suggests that\nthe paired configuration is not responsible for the observed plane of\nsatellites in the Milky Way. The results in this study indicate the paired\nconfiguration could bring some nonnegligible effect on the subhalo abundance in\nthe investigation of the Milky Way's satellite problems." }, { "anchor": "In Search of an Interface between Warm and Hot Gas within the Local\n Bubble: We have examined UV spectra recorded by the Space Telescope Imaging\nSpectrograph (STIS) on the Hubble Space Telescope for three stars, HD32309, 41\nAri, and $\\eta$~Tel, that are located well inside the boundary of the Local Hot\nBubble in our search for absorption features of Si IV, C IV, and N V that could\nreveal the presence of an interface between the local warm ($T\\sim 7000$ K)\nneutral medium and a more distant hot ($T\\sim 10^6$ K) interstellar medium. In\nall cases, we failed to detect such ions. Our most meaningful upper limit is\nthat for log N(C IV)< 11.86 toward HD32309, which is below the expectation for\na sight line that penetrates either a conductive/evaporative interface or a\nturbulent mixing layer. We offer conjectures on the reasons for these negative\nresults in terms of either a suppression of a conductive layer caused by the\nshielding of the local cloud by other clouds, which may make it more difficult\nfor us to sense discrete absorption features from gases at intermediate\ntemperatures, or by the presence of a tangential magnetic field at most\nlocations on the surface of the local cloud.", "positive": "The evolution of M 2-9 from 2000 to 2010: M 2-9, the Butterfly nebula, is an outstanding representative of extreme\naspherical flows. It presents unique features such as a pair of high-velocity\ndusty polar blobs and a mirror-symmetric rotating pattern in the inner lobes.\nImaging monitoring of the evolution of the nebula in the past decade is\npresented. We determine the proper motions of the dusty blobs, which infer a\nnew distance estimate of 1.3+-0.2 kpc, a total nebular size of 0.8 pc, a speed\nof 147 km/s, and a kinematical age of 2500 yr. The corkscrew geometry of the\ninner rotating pattern is quantified. Different recombination timescales for\ndifferent ions explain the observed surface brightness distribution. According\nto the images taken after 1999, the pattern rotates with a period of 92+-4 yr.\nOn the other hand, the analysis of images taken between 1952 and 1977 measures\na faster angular velocity. If the phenomenon were related to orbital motion,\nthis would correspond to a modest orbital eccentricity (e=0.10+-0.05), and a\nslightly shorter period (86+-5 yr). New features have appeared after 2005 on\nthe west side of the lobes and at the base of the pattern. The geometry and\ntravelling times of the rotating pattern support our previous proposal that the\nphenomenon is produced by a collimated spray of high velocity particles (jet)\nfrom the central source, which excites the walls of the inner cavity of M 2-9,\nrather than by a ionizing photon beam. The speed of such a jet would be\nremarkable: between 11000 and 16000 km/s. The rotating-jet scenario may explain\nthe formation and excitation of most of the features observed in the inner\nnebula, with no need for additional mechanisms, winds, or ionization sources.\nAll properties point to a symbiotic-like interacting binary as the central\nsource of M 2-9." }, { "anchor": "A Model for Clumpy Self-Enrichment in Globular Clusters: Detailed observations of globular clusters (GCs) have revealed evidence of\nself-enrichment: some of the heavy elements that we see in stars today were\nproduced by cluster stars themselves. Moreover, GCs have internal\nsubpopulations with different elemental abundances, including, in some cases,\nin elements such as iron that are produced by supernovae. This paper presents a\ntheoretical model for GC formation motivated by observations of Milky Way star\nforming regions and simulations of star formation, where giant molecular clouds\nfragment into multiple clumps which undergo star formation at slightly\ndifferent times. Core collapse supernovae from earlier-forming clumps can\nenrich later-forming clumps to the degree that the ejecta can be retained\nwithin the gravitational potential well, resulting in subpopulations with\ndifferent total metallicities once the clumps merge to form the final cluster.\nThe model matches the mass-metallicity relation seen in GC populations around\nmassive elliptical galaxies, and predicts metallicity spreads within clusters\nin excellent agreement with those seen in Milky Way GCs, even for those whose\ninternal abundance spreads are so large that their entire identity as a GC is\nin question. The internal metallicity spread serves as an excellent measurement\nof how much self-enrichment has occurred in a cluster, a result that is very\nrobust to variation in the model parameters.", "positive": "GLACE survey: galaxy activity in ZwCl0024+1652 cluster from strong\n optical emission lines: Although ZwCl0024+1652 galaxy cluster at $z\\sim0.4$ has been thoroughly\nanalysed, it lacks a comprehensive study of star formation and nuclear activity\nof its members. With GaLAxy Cluster Evolution (GLACE) survey, a total of 174\nH$\\alpha$ emission-line galaxies (ELGs) were detected, most of them having\n[NII}]. We reduced and analysed a set of [OIII] and H$\\beta$ tunable filter\n(TF) observations within GLACE survey. Using H$\\alpha$ priors, we identified\n[OIII] and H$\\beta$ in 35 ($\\sim$20%) and 59 ($\\sim$34%) sources, respectively,\nwith 21 of them having both emission lines, and 20 having in addition [NII].\nApplying BPT-NII diagnostic diagram, we classified these ELGs into 40%\nstar-forming (SF), 55% composites, and 5% LINERs. Star formation rate (SFR)\nmeasured through extinction corrected H$\\alpha$ fluxes increases with stellar\nmass ($\\mathrm{M}_{*}$), attaining its peak at\n$\\mathrm{M}_{*}\\sim10^{9.8}\\mathrm{M}_\\odot$. We observed that the cluster\ncentre to $\\sim$1.3Mpc is devoid of SF galaxies and AGN. Our results suggest\nthat the star formation efficiency declines as the local density increases in\nthe cluster medium. Moreover, the SF and AGN fractions drop sharply towards\nhigh-density environments. We observed a strong decline in SF fraction in high\n$\\mathrm{M}_*$, confirming that star formation is highly suppressed in\nhigh-mass cluster galaxies. Finally, we determined that SFR correlates with\n$\\mathrm{M}_*$ while specific SFR (sSFR) anti-correlates with $\\mathrm{M}_*$,\nboth for cluster and field. This work shows the importance and strength of TF\nobservations when studying ELGs in clusters at higher redshifts. We provide\nwith this paper a catalogue of ELGs with H$\\beta$ and/or [OIII] lines in\nZwCl0024+1652 cluster." }, { "anchor": "Carbon and nitrogen abundances of individual stars in the Sculptor dwarf\n spheroidal galaxy: We present [C/Fe] and [N/Fe] abundance ratios and CH({\\lambda}4300) and\nS({\\lambda}3883) index measurements for 94 red giant branch (RGB) stars in the\nSculptor dwarf spheroidal galaxy from VLT/VIMOS MOS observations at a resolving\npower R= 1150 at 4020 {\\AA}. This is the first time that [N/Fe] abundances are\nderived for a large number of stars in a dwarf spheroidal. We found a trend for\nthe [C/Fe] abundance to decrease with increasing luminosity on the RGB across\nthe whole metallicity range, a phenomenon observed in both field and globular\ncluster giants, which can be interpreted in the framework of evolutionary\nmixing of partially processed CNO material. Both our measurements of [C/Fe] and\n[N/Fe] are in good agreement with the theoretical predictions for stars at\nsimilar luminosity and metallicity. We detected a dispersion in the carbon\nabundance at a given [Fe/H], which cannot be ascribed to measurement\nuncertainties alone. We interpret this observational evidence as the result of\nthe contribution of different nucleosynthesis sources over time to a not\nwell-mixed interstellar medium. We report the discovery of two new\ncarbon-enhanced, metal-poor stars. These are likely the result of pollution\nfrom material enriched by asymptotic giant branch stars, as indicated by our\nestimates of [Ba/Fe]> +1. We also attempted a search for dissolved globular\nclusters in the field of the galaxy by looking for the distinctive C-N pattern\nof second population globular clusters stars in a previously detected, very\nmetal-poor, chemodynamical substructure. We do not detect chemical anomalies\namong this group of stars. However, small number statistics and limited spatial\ncoverage do not allow us to exclude the hypotheses that this substructure forms\npart of a tidally shredded globular cluster.", "positive": "Warm gas in the rotating disk of the Red Rectangle: accurate models of\n molecular line emission: We aim to study the excitation conditions of the molecular gas in the\nrotating disk of the Red Rectangle, the only post-Asymptotic-Giant-Branch\nobject in which the existence of an equatorial rotating disk has been\ndemonstrated. For this purpose, we developed a complex numerical code that\naccurately treats radiative transfer in 2-D, adapted to the study of molecular\nlines from rotating disks.\n We present far-infrared Herschel/HIFI observations of the 12CO and 13CO\nJ=6-5, J=10-9, and J=16-15 transitions in the Red Rectangle. We also present\nour code in detail and discuss the accuracy of its predictions, from comparison\nwith well-tested codes. Theoretical line profiles are compared with the\nempirical data to deduce the physical conditions in the disk by means of model\nfitting.\n We conclude that our code is very efficient and produces reliable results.\nThe comparison of the theoretical predictions with our observations reveals\nthat the temperature of the Red Rectangle disk is typically ~ 100-150 K, about\ntwice as high as previously deduced from mm-wave observations of lower-J lines.\nWe discuss the relevance of these new temperature estimates for understanding\nthe thermodynamics and dynamics of this prototype object, as well as for\ninterpreting observations of other rarely studied post-AGB disks. Despite our\nsophisticated treatment of the line formation, our model cannot explain the\nrelatively strong line-wing emission for intermediate-J transitions. We argue\nthat a model including a rotating disk only cannot reproduce these data and\nsuggest that there is an additional extended (probably bipolar) structure\nexpanding at about 7--15 km/s." }, { "anchor": "Nuclear Star Clusters: We review the current knowledge about nuclear star clusters (NSCs), the\nspectacularly dense and massive assemblies of stars found at the centers of\nmost galaxies. Recent observational and theoretical work suggest that many NSC\nproperties, including their masses, densities, and stellar populations vary\nwith the properties of their host galaxies. Understanding the formation,\ngrowth, and ultimate fate of NSCs therefore is crucial for a complete picture\nof galaxy evolution. Throughout the review, we attempt to combine and distill\nthe available evidence into a coherent picture of NSC evolution. Combined, this\nevidence points to a clear transition mass in galaxies of ~10^9 solar masses\nwhere the characteristics of nuclear star clusters change. We argue that at\nlower masses, NSCs are formed primarily from globular clusters that inspiral\ninto the center of the galaxy, while at higher masses, star formation within\nthe nucleus forms the bulk of the NSC. We also discuss the coexistence of NSCs\nand central black holes, and how their growth may be linked. The extreme\ndensities of NSCs and their interaction with massive black holes lead to a wide\nrange of unique phenomena including tidal disruption and gravitational wave\nevents. Lastly, we review the evidence that many NSCs end up in the halos of\nmassive galaxies stripped of the stars that surrounded them, thus providing\nvaluable tracers of the galaxies' accretion histories.", "positive": "Measuring the local dark matter density: We examine systematic problems in determining the local matter density from\nthe vertical motion of stars, i.e. the 'Oort limit'. Using collisionless\nsimulations and a Monte Carlo Markov Chain technique, we determine the data\nquality required to detect local dark matter at its expected density. We find\nthat systematic errors are more important than observational errors and apply\nour technique to Hipparcos data to reassign realistic error bars to the local\ndark matter density." }, { "anchor": "Revisiting Rotation Measures from the Canadian Galactic Plane Survey:\n the Magnetic Field in the Disk of the Outer Galaxy: Faraday rotation provides a valuable tracer of magnetic fields in the\ninterstellar medium; catalogs of Faraday rotation measures provide key\nobservations for studies of the Galactic magnetic field. We present a new\ncatalog of rotation measures derived from the Canadian Galactic Plane Survey,\ncovering a large region of the Galactic plane spanning 52 deg < l < 192 deg, -3\ndeg < b < 5 deg, along with northern and southern latitude extensions around l\n~ 105 deg. We have derived rotation measures for 2234 sources (4 of which are\nknown pulsars), 75% of which have no previous measurements, over an area of\napproximately 1300 square degrees. These new rotation measures increase the\nmeasurement density for this region of the Galactic plane by a factor of two.", "positive": "Galaxy and Mass Assembly (GAMA): Accurate number densities &\n environments of massive ultracompact galaxies at 0.02 < z < 0.3: Massive Ultracompact Galaxies (MUGs) are common at z=2-3, but very rare in\nthe nearby Universe. Simulations predict that the few surviving MUGs should\nreside in galaxy clusters, whose large relative velocities prevent them from\nmerging, thus maintaining their original properties (namely stellar\npopulations, masses, sizes and dynamical state). We take advantage of the\nhigh-completeness, large-area spectroscopic GAMA survey, complementing it with\ndeeper imaging from the KiDS and VIKING surveys. We find a set of 22 bona-fide\nMUGs, defined as having high stellar mass (>8x10^10 M_Sun) and compact size\n(R_e<2 Kpc) at 0.02 < z < 0.3. An additional set of 7 lower-mass objects\n(6x10^10 < M_star/M_Sun < 8x10^10) are also potential candidates according to\ntypical mass uncertainties. The comoving number density of MUGs at low redshift\n(z < 0.3) is constrained at $(1.0\\pm 0.4)x 10^-6 Mpc^-3, consistent with galaxy\nevolution models. However, we find a mixed distribution of old and young\ngalaxies, with a quarter of the sample representing (old) relics. MUGs have a\npredominantly early/swollen disk morphology (Sersic index 1 ~ 10^10 M_Sun Kpc^-2). Interestingly, a\nlarge fraction feature close companions -- at least in projection -- suggesting\nthat many (but not all) reside in the central regions of groups. Halo masses\nshow these galaxies inhabit average-mass groups. As MUGs are found to be almost\nequally distributed among environments of different masses, their relative\nfraction is higher in more massive overdensities, matching the expectations\nthat some of these galaxies fell in these regions at early times. However,\nthere must be another channel leading some of these galaxies to an abnormally\nlow merger history because our sample shows a number of objects that do not\ninhabit particularly dense environments. (abridged)" }, { "anchor": "Bulgeless Galaxies at Intermediate Redshift: Sample Selection, Colour\n Properties, and the Existence of Powerful AGN: We present a catalogue of bulgeless galaxies, which includes 19225 objects\nselected in four of the deepest, largest multi-wavelength datasets available --\nCOSMOS, AEGIS, GEMS and GOODS -- at intermediate redshift ($0.4 \\leq z \\leq\n1.0$). The morphological classification was provided by the Advanced Camera for\nSurveys General Catalogue (ACS-GC), which used publicly available data obtained\nwith the ACS instrument on the Hubble Space Telescope. Rest-frame photometric\nquantities were derived using kcorrect. We analyse the properties of the sample\nand the evolution of pure-disc systems with redshift. Very massive [$\\log\n(M_\\star/M_{\\odot}) > 10.5$] bulgeless galaxies contribute to ~30% of the total\ngalaxy population number density at $z \\geq 0.7$, but their number density\ndrops substantially with decreasing redshift. We show that only a negligible\nfraction of pure discs appear to be quiescent systems, and red sequence\nbulgeless galaxies show indications of dust-obscured star formation. X-ray\ncatalogues were used to search for X-ray emission within our sample. After\nvisual inspection and detailed parametric morphological fitting we identify 30\nAGN that reside in galaxies without a classical bulge. The finding of such\npeculiar objects at intermediate redshift shows that while AGN growth in\nmerger-free systems is a rare event (0.2% AGN hosts in this sample of bulgeless\ngalaxies), it can indeed happen relatively early in the Universe history.", "positive": "Deep and narrow CO absorption revealing molecular clouds in the Hydra-A\n brightest cluster galaxy: Active galactic nuclei play a crucial role in the accretion and ejection of\ngas in galaxies. Although their outflows are well studied, finding direct\nevidence of accretion has proved very difficult and has so far been done for\nvery few sources. A promising way to study the significance of cold accretion\nis by observing the absorption of an active galactic nucleus's extremely bright\nradio emission by the cold gas lying along the line-of-sight. As such, we\npresent ALMA CO(1-0) and CO(2-1) observations of the Hydra-A brightest cluster\ngalaxy (z=0.054) which reveal the existence of cold, molecular gas clouds along\nthe line-of-sight to the galaxy's extremely bright and compact mm-continuum\nsource. They have apparent motions relative to the central supermassive black\nhole of between -43 and -4 km s$^{-1}$ and are most likely moving along stable,\nlow ellipticity orbits. The identified clouds form part of a $\\sim$$10^{9}$\n$\\text{M}_{\\odot}$, approximately edge-on disc of cold molecular gas. With peak\nCO(2-1) optical depths of $\\tau$=0.88 $^{+0.06}_{-0.06}$, they include the\nnarrowest and by far the deepest absorption of this type which has been\nobserved to date in a brightest cluster galaxy. By comparing the relative\nstrengths of the lines for the most strongly absorbing region, we are able to\nestimate a gas temperature of $42^{+25}_{-11}$ K and line-of-sight column\ndensities of $N_{CO}=2^{+3}_{-1}\\times 10 ^{17} cm^{-2}$ and $N_{ H_{2}\n}=7^{+10}_{-4}\\times 10 ^{20} cm^{-2}$." }, { "anchor": "Regulation of Star Formation Rates in Multiphase Galactic Disks:\n Numerical Tests of the Thermal/Dynamical Equilibrium Model: We use vertically-resolved numerical hydrodynamic simulations to study star\nformation and the interstellar medium (ISM) in galactic disks. We focus on\nouter disk regions where diffuse HI dominates, with gas surface densities\nSigma_SFR=3-20 Msun/kpc^2/yr and star-plus-dark matter volume densities\nrho_sd=0.003-0.5 Msun/pc^3. Star formation occurs in very dense, cold,\nself-gravitating clouds. Turbulence, driven by momentum feedback from supernova\nevents, destroys bound clouds and puffs up the disk vertically. Time-dependent\nradiative heating (FUV) offsets gas cooling. We use our simulations to test a\nnew theory for self-regulated star formation. Consistent with this theory, the\ndisks evolve to a state of vertical dynamical equilibrium and thermal\nequilibrium with both warm and cold phases. The range of star formation surface\ndensities and midplane thermal pressures is Sigma_SFR ~ 0.0001 - 0.01\nMsun/kpc^2/yr and P_th/k_B ~ 100 -10000 cm^-3 K. In agreement with\nobservations, turbulent velocity dispersions are ~7 km/s and the ratio of the\ntotal (effective) to thermal pressure is P_tot/P_th~4-5, across this whole\nrange. We show that Sigma_SFR is not well correlated with Sigma alone, but\nrather with Sigma*(rho_sd)^1/2, because the vertical gravity from stars and\ndark matter dominates in outer disks. We also find that Sigma_SFR has a strong,\nnearly linear correlation with P_tot, which itself is within ~13% of the\ndynamical-equilibrium estimate P_tot,DE. The quantitative relationships we find\nbetween Sigma_SFR and the turbulent and thermal pressures show that star\nformation is highly efficient for energy and momentum production, in contrast\nto the low efficiency of mass consumption. Star formation rates adjust until\nthe ISM's energy and momentum losses are replenished by feedback within a\ndynamical time.", "positive": "Detection of a second high velocity component in the highly ionized wind\n from PG 1211+143: An extended XMM-Newton observation of the luminous narrow line Seyfert galaxy\nPG 1211+143 in 2014 has revealed a more complex highly ionized, high velocity\noutflow. The detection of previously unresolved spectral structure in Fe K\nabsorption finds a second outflow velocity component of the highly ionized\nwind, with an outflow velocity of v~0.066+/-0.003c, in addition to a still\nhigher velocity outflow of v~0.129+/-0.002c consistent with that first seen in\n2001. We note that chaotic accretion, consisting of many prograde and\nretrograde events, offers an intriguing explanation of the dual velocity wind.\nIn that context the persisting outflow velocities could relate to physically\ndistinct orientations of the inner accretion flow, with prograde accretion\nyielding a higher launch velocity than retrograde accretion in a ratio close to\nthat observed." }, { "anchor": "Seyfert 1 Composite Spectrum using SDSS Legacy Survey Data: We present a rest-frame composite spectrum for Seyfert 1 galaxies using\nspectra obtained from the DR12 release of the Sloan Digital Sky Survey (SDSS).\nThe spectrum is constructed by combining data from a total of 10,112 galaxies,\nspanning a redshift range of 0 to 0.793. We produce an electronic table of the\nmedian and geometric mean composite Seyfert 1 spectrum. We measure the spectral\nindex of the composite spectrum, and compare it with that of the composite\nquasar spectrum. We also measure the flux and width of the strong emission\nlines present in the composite spectrum. We compare the entire spectrum with\nthe quasar spectrum in the context of the AGN unification model. The two\ncomposite spectra match extremely well in the blue part of the spectrum, while\nthere is an offset in flux in the red portion of the spectrum.", "positive": "Low star-formation activity and low gas content of quiescent galaxies at\n $z=$ 3.5-4.0 constrained with ALMA: The discovery in deep near-infrared surveys of a population of massive\nquiescent galaxies at $z>3$ has given rise to the question of how they came to\nbe quenched so early in the history of the Universe. Measuring their molecular\ngas properties can distinguish between physical processes where they stop\nforming stars due to a lack of fuel versus those where star-formation\nefficiency is reduced and the gas is retained. We conducted Atacama Large\nMillimeter/sub-millimeter Array (ALMA) observations of four quiescent galaxies\nat $z=$ 3.5-4.0 found by the Fourstar Galaxy Evolution Survey (ZFOURGE) and a\nserendipitous optically dark galaxy at $z=3.71$. We aim to investigate the\npresence of dust-obscured star-formation and their gas content by observing the\ndust continuum emission at Band-7 and the atomic carbon [C I]($^3P_1$-$^3P_0$)\nline at 492.16 GHz. Among the four quiescent galaxies, only one source is\ndetected in the dust continuum at $\\lambda_{\\rm obs} = 870 {\\rm \\mu m}$. The\nsub-mm observations confirm their passive nature, and all of them are located\nmore than four times below the main sequence of star-forming galaxies at\n$z=3.7$. None of the targets are detected in [C I], constraining their gas mass\nfractions to be $<$ 20%. These gas mass fractions are more than three times\nlower than the scaling relation for star-forming galaxies at $z=3.7$. These\nresults support scenarios where massive galaxies at $z=$ 3.5-4.0 quench by\nconsuming/expelling all the gas rather than by reducing the efficiency of the\nconversion of their gas into stars." }, { "anchor": "Red Giant Branch Bump Brightness and Number Counts in 72 Galactic\n Globular Clusters Observed with the Hubble Space Telescope: We present the broadest and most precise empirical investigation of red giant\nbranch bump (RGBB) brightness and number counts ever conducted. We implement a\nnew method and use data from two \\textit{Hubble Space Telescope (HST)} globular\ncluster (GC) surveys to measure the brightness and star counts of the RGBB in\n72 GCs. The brightness is measured to a precision better than 0.01 mag while\nthe precision in number counts reaches 10%. The position of the main-sequence\nturnoff (MSTO) and the number of horizontal branch (HB) stars are used as\ncomparisons where appropriate. Several independent scientific conclusions are\nnewly possible with our parametrization of the RGBB. Both brightness and number\ncounts are shown to have second parameters in addition to their strong\ndependence on metallicity. The RGBBs are found to be anomalous in the GCs NGC\n2808, 5286, 6388 and 6441, likely due to the presence of multiple populations.\nFinally, we use our empirical calibration to predict the properties of the\nGalactic bulge RGBB if the assumption of similar stellar physics for the bulge\nand Galactic GC system holds. The RGBB properties for the bulge are shown to\ndiffer from those of the Galactic GC system, with the former having lower\nnumber counts, a lower brightness dispersion and a brighter peak luminosity\nthan would be expected from the latter. This discrepancy is well explained by\nthe Galactic bulge having a higher helium abundance than expected from GCs,\n${\\Delta}$Y$\\sim +$0.06 at the median metallicity.", "positive": "An Analysis of the Population of Extended Main Sequence Turn-off\n Clusters in the Large Magellanic Cloud: We combine a number of recent studies of the extended main sequence turn-off\n(eMSTO) phenomenon in intermediate age stellar ($1-2$ Gyr) clusters in the\nLarge Magellanic Cloud (LMC) in order to investigate its origin. By employing\nthe largest sample of eMSTO LMC clusters so far used, we show that cluster core\nradii, masses, and dynamical state are not related to the genesis of eMSTOs.\nIndeed, clusters in our sample have core radii, masses and age-relaxation time\nratios in the range $\\approx$ 2--6 pc, 3.35- 5.50 (log($M_{cls}$/$M_\\odot$) and\n0.2-8.0, respectively. These results imply that the eMSTO phenomenon is not\ncaused by actual age spreads within the clusters. Furthermore, we confirm from\na larger cluster sample recent results including young eMSTO LMC clusters, that\nthe FWHM at the MSTOs correlates most strongly with cluster age, suggesting\nthat a stellar evolutionary effect is the underlying cause." }, { "anchor": "Reconstructing the genesis of a globular cluster system at a look-back\n time of 9.1 Gyr with the JWST: Using early-release data from the JWST, Mowla et al. and Claeyssens et al.\nrecently measured various properties for gravitationally lensed compact sources\n(`sparkles') around the `Sparkler' galaxy at a redshift of 1.378 (a look-back\ntime of 9.1 Gyr). Here, we focus on the Mowla et al. as they were able to break\nthe age-metallicity degeneracy and derive independent ages, metallicities and\nextinctions for each source. They identified 5 metal-rich, old GC candidates\n(with formation ages up to $\\sim$13 Gyr). We examine the age--metallicity\nrelation (AMR) for the GC candidates and other Sparkler compact sources. The\nSparkler galaxy, which has a current estimated stellar mass of 10$^9$\nM$_{\\odot}$, is compared to the Large Magellanic Cloud (LMC), the disrupted\ndwarf galaxy Gaia--Enceladus and the Milky Way (MW). The Sparkler galaxy\nappears to have undergone very rapid chemical enrichment in the first few\nhundred Myr after formation, with its GC candidates similar to those of the\nMW's metal-rich subpopulation. We also compare the Sparkler to theoretical AMRs\nand formation ages from the E-MOSAICS simulation, finding the early formation\nage of its GCs to be in some tension with these predictions for MW-like\ngalaxies. The metallicity of the Sparkler's star forming regions are more akin\nto a galaxy of stellar mass $\\ge$ 10$^{10.5}$ M$_{\\odot}$, i.e. at the top end\nof the expected mass growth over 9.1 Gyr of cosmic time. We conclude that the\nSparkler galaxy may represent a progenitor of a MW-like galaxy, even including\nthe ongoing accretion of a satellite galaxy.", "positive": "A Formation Scenario for the Disk of Satellites: Accretion of Satellites\n during Mergers: The Disk of Satellites (DoS) observed in the Andromeda galaxy is a thin and\nextended group of satellites, nearly perpendicular to the disk plane, that\nshare a common direction of rotation about the centre of Andromeda. Although a\nDoS is also observed in the Milky Way galaxy, the prevalance of such structures\nin more distant galaxies remains controversial. Explanations for the formation\nof such DoSs vary widely from filamentary infall, or flattening due to the\npotential field from large scale structure, to galaxy interactions in a Mondian\nparadigm. Here we present an alternative scenario -- during a merger, a galaxy\nmay bring its own satellite population when merging with another galaxy. We\ndemonstrate how, under the correct circumstances, during the coalescence of the\ntwo galaxies, the satellite population can be spread into an extended,\nflattened structure, with a common direction of rotation about the merger\nremnant. We investigate the key parameters of the interaction, and the\nsatellite population, that are required to form a DoS in this scenario." }, { "anchor": "A catalogue of faint local radio AGN and the properties of their host\n galaxies: We present a catalogue of local ($z<0.1$) galaxies that contain faint AGN. We\nselect these objects by identifying galaxies that exhibit a significant excess\nin their radio luminosities, compared to what is expected from the observed\nlevels of star-formation activity in these systems. This is achieved by\ncomparing the optical (spectroscopic) star formation rate (SFR) to the 1.4~GHz\nluminosity measured from the FIRST survey. The majority of the AGN identified\nin this study are fainter than those in previous work, such as in the Best and\nHeckman (2012) catalogue. We show that these faint AGN make a non-negligible\ncontribution to the radio luminosity function at low luminosities (below\n$10^{22.5}$ W Hz$^{-1}$), and host $\\sim$13 per cent of the local radio\nluminosity budget. Their host galaxies are predominantly high stellar-mass\nsystems (with a median stellar mass of $10^{11}\\textrm{M}_{\\odot}$), are found\nacross a range of environments (but typically in denser environments than\nstar-forming galaxies) and have early-type morphologies. This study\ndemonstrates a general technique to identify AGN in galaxy populations where\nreliable optical SFRs can be extracted using spectro-photometry and where radio\ndata are also available so that a radio excess can be measured. Our results\nalso demonstrate that it is unsafe to infer SFRs from radio emission\n\\textit{alone}, even if bright AGN have been excluded from a sample, since\nthere is a significant population of faint radio AGN which may contaminate the\nradio-derived SFRs.", "positive": "CO ro-vibrational lines in HD100546: A search for disc asymmetries and\n the role of fluorescence: We have studied the emission of CO ro-vibrational lines in the disc around\nthe Herbig Be star HD100546 with the final goal of using these lines as a\ndiagnostic to understand inner disc structure in the context of planet\nformation. High-resolution IR spectra of CO ro-vibrational emission at eight\ndifferent position angles were taken with CRIRES at the VLT. From these spectra\nflux tables, CO ro-vibrational line profiles, and population diagrams were\nproduced. We have investigated variations in the line profile shapes and line\nstrengths as a function of slit position angle. We used the thermochemical disc\nmodelling code ProDiMo based on the chemistry, radiation field, and temperature\nstructure of a previously published model for HD100546. Comparing observations\nand the model, we investigated the possibility of disc asymmetries, the\nexcitation mechanism (UV fluorescence), the geometry, and physical conditions\nof the inner disc. The observed CO ro-vibrational lines are largely emitted\nfrom the inner rim of the outer disc at 10-13 AU. The line shapes are similar\nfor all v levels and line fluxes from all vibrational levels vary only within\none order of magnitude. All line profile asymmetries and variations can be\nexplained with a symmetric disc model to which a slit correction and pointing\noffset is applied. Because the angular size of the CO emitting region (10-13\nAU) and the slit width are comparable the line profiles are very sensitive to\nthe placing of the slit. The model reproduces the line shapes and the fluxes of\nthe v=1-0 lines as well as the spatial extent of the CO ro-vibrational\nemission. It does not reproduce the observed band ratios of 0.5-0.2 with higher\nvibrational bands. We find that lower gas volume densities at the surface of\nthe inner rim of the outer disc can make the fluorescence pumping more effcient\nand reproduce the observed band ratios." }, { "anchor": "Spatially resolved properties for extremely metal-poor star-forming\n galaxies with Wolf-Rayet features and high-ionization lines: Extremely metal-poor, high-ionizing starbursts in the local Universe provide\nunique laboratories for exploring in detail the physics of high-redshift\nsystems. Also, their ongoing star-formation and haphazard morphology make them\noutstanding proxies for primordial galaxies. Using integral field spectroscopy,\nwe spatially resolved the ISM properties and massive stars of two first-class\nlow metallicity galaxies with Wolf-Rayet features and nebular HeII emission:\nMrk178 and IZw18. In this review, we summarize our main results for these two\nobjects.", "positive": "Spikes and accretion of unbound, collisionless matter around black holes: We consider the steady-state density and velocity dispersion profiles of\ncollisionless matter around a Schwarzschild black hole (BH) and its associated\nrate of accretion onto the BH. We treat matter, which could be stars or dark\nmatter particles, whose orbits are {\\it unbound} to the BH, but still governed\nby its gravitational field. We consider two opposite spatial geometries for the\nmatter distributions: an infinite, 3D cluster and a 2D razor-thin disk, both\nwith zero net angular momentum. We demonstrate that the results depend\ncritically on the adopted geometry, even in the absence of angular momentum. We\nadopt a simple monoenergetic, isotropic, phase-space distribution function for\nthe matter as a convenient example to illustrate this dependence. The effect of\nbreaking strict isotropy by incorporating an unreplenished loss cone due to BH\ncapture of low-angular momentum matter is also considered. Calculations are all\nanalytic and performed in full general relativity, though key results are also\nevaluated in the Newtonian limit. We consider one application to show that the\nrate of BH accretion from an ambient cluster can be significantly less than\nthat from a thin disk to which it may collapse, although both rates are\nconsiderably smaller than Bondi accretion for a (collisional) fluid with a\nsimilar asymptotic particle density and velocity dispersion (i.e., sound\nspeed)." }, { "anchor": "Disk Polarization From Both Emission and Scattering of Magnetically\n Aligned Grains: The Case of NGC 1333 IRAS4A1: Dust polarization in millimeter (and centimeter) has been mapped in disks\naround an increasing number of young stellar objects. It is usually thought to\ncome from emission by magnetically aligned (non-spherical) grains, but can also\nbe produced by dust scattering. We present a semi-analytic theory of disk\npolarization that includes both the direction emission and scattering, with an\nemphasis on their relative importance and how they are affected by the disk\ninclination. For face-on disks, both emission and scattering tend to produce\npolarization in the radial direction, making them difficult to distinguish,\nalthough the scattering-induced polarization can switch to the azimuthal\ndirection if the incident radiation is beamed strongly enough in the radial\ndirection in the disk plane. Disk inclination affects the polarizations from\nemission and scattering differently, especially on the major axis where, in the\nedge-on limit, the former vanishes while the latter reaches a polarization\nfraction as large as 1/3. The polarizations from the two competing mechanisms\ntend to cancel each other on the major axis, producing two low polarization\n\"holes\" (one on each side of the center) under certain conditions. We find\ntantalizing evidence for at least one such \"hole\" in NGC1333 IRAS4A1, whose\npolarization observed at 8 mm on the 100 AU scale is indicative of a pattern\ndominated by scattering close to the center and by direction emission in the\nouter region. If true, it would imply not only that a magnetic field exists on\nthe disk scale, but that it is strong enough to align large, possibly mm-sized,\ngrains.", "positive": "Does the HCN/CO ratio trace the star-forming fraction of gas? I. A\n comparison with analytical models of star formation: We use archival ALMA observations of the HCN and CO $J=1-0$ transitions, in\naddition to the radio continuum at 93 GHz, to assess the relationship between\ndense gas, star formation, and gas dynamics in ten, nearby (U)LIRGs and\nlate-type galaxy centers. We frame our results in the context of turbulent and\ngravoturbulent models of star formation to assess if the HCN/CO ratio tracks\nthe gravitationally-bound, star-forming gas in molecular clouds\n($f_\\mathrm{grav}$) at sub-kpc scales in nearby galaxies. We confirm that the\nHCN/CO ratio is a tracer of gas above $n_\\mathrm{SF}\\approx10^{4.5}$ cm$^{-3}$,\nbut the sub-kpc variations in HCN/CO do not universally track\n$f_\\mathrm{grav}$. We find strong evidence for the use of varying star\nformation density threshold models, which are able to reproduce trends observed\nin $t_\\mathrm{dep}$ and $\\epsilon_\\mathrm{ff}$ that fixed threshold models\ncannot. Composite lognormal and powerlaw models outperform pure lognormal\nmodels in reproducing the observed trends, even when using a fixed powerlaw\nslope. The ability of the composite models to better reproduce star formation\nproperties of the gas provides additional indirect evidence that the star\nformation efficiency per free-fall time is proportional to the fraction of\ngravitationally-bound gas." }, { "anchor": "RAVE stars in K2 - I. Improving RAVE red giants spectroscopy using\n asteroseismology from K2 Campaign 1: We present a set of 87 RAVE stars with detected solar like oscillations,\nobserved during Campaign 1 of the K2 mission (RAVE K2-C1 sample). This dataset\nprovides a useful benchmark for testing the gravities provided in RAVE Data\nRelease 4 (DR4), and is key for the calibration of the RAVE Data Release 5\n(DR5). In the present work, we use two different pipelines, GAUFRE (Valentini\net al. 2013) and Sp_Ace (Boeche & Grebel 2016), to determine atmospheric\nparameters and abundances by fixing log(g) to the seismic one. Our strategy\nensures highly consistent values among all stellar parameters, leading to more\naccurate chemical abundances. A comparison of the chemical abundances obtained\nhere with and without the use of seismic log(g) information has shown that an\nunderestimated (overestimated) gravity leads to an underestimated\n(overestimated) elemental abundance (e.g. [Mg/H] is underestimated by ~0.25 dex\nwhen the gravity is underestimated by 0.5 dex). We then perform a comparison\nbetween the seismic gravities and the spectroscopic gravities presented in the\nRAVE DR4 catalogue, extracting a calibration for log(g) of RAVE giants in the\ncolour interval 0.50<(J - Ks)<0.85. Finally, we show a comparison of the\ndistances, temperatures, extinctions (and ages) derived here for our RAVE K2-C1\nsample with those derived in RAVE DR4 and DR5.DR5 performs better than DR4\nthanks to the seismic calibration, although discrepancies can still be\nimportant for objects for which the difference between DR4/DR5 and seismic\ngravities differ by more than ~0.5 dex. The method illustrated in this work\nwill be used for analysing RAVE targets present in the other K2 campaigns, in\nthe framework of Galactic Archaeology investigations.", "positive": "The role of turbulence in the warm ionized medium: We discuss the role of turbulence in establishing the observed emission\nmeasures and ionization of the warm ionized medium. A Monte Carlo radiative\ntransfer code applied to a snapshot of a simulation of a supernova-driven,\nmulti-temperature, stratified ISM reproduces the essential observed features of\nthe WIM." }, { "anchor": "Prospects for detecting CII emission during the Epoch of Reionization: We produce simulations of emission of the atomic CII line in large sky fields\nin order to determine the current prospects for mapping this line during the\nhigh redshift Epoch of Reionization. We estimate the CII line intensity,\nredshift evolution and spatial fluctuations using observational relations\nbetween CII emission and the SFR in a galaxy for the frequency range of 200 GHz\nto 300 GHz. We obtained a frequency averaged intensity of CII emission of ${\\rm\nI_{\\rm CII}=(4 \\pm 2)\\times10^{2}\\, Jy\\, \\rm sr^{-1}}$ in the redshift range\n$z\\, \\sim\\, 5.3\\, -\\, 8.5$. Observations of CII emission in this frequency\nrange will suffer contamination from emission lines at lower redshifts, in\nparticular from the CO rotation lines. For the relevant frequency range we\nestimated the CO contamination (originated in emission from galaxies at $z\\,\n<\\, 2.5$), using simulations, to be ${\\rm I_{\\rm CO} \\approx 10^{3}\\, Jy \\,\nsr^{-1}}$ and independently confirmed the result based in observational\nrelations. We generated maps as a function of angle and frequency using\ndetailed simulations of the CII and CO emission across several redshifts in\norder to properly take into account the observational pipeline and light cone\neffects. In order to reduce the foreground contamination we found that we\nshould mask galaxies below redshifts $\\sim 2.5$ with a CO flux in one of the\nCO(J:2-1) to CO(J:6-5) lines higher than ${\\rm 5\\times 10^{-22}\\, W\\ m^{-2}}$\nor a AB magnitude lower than ${\\rm m_{\\rm K}\\, =\\, 22}$. We estimate that the\nadditional continuum contamination is of the order of ${\\rm 10^{5}\\, Jy\\,\nsr^{-1}}$. It is also considered the possibility of cross correlating\nforeground lines with galaxies in order to probe the intensity of the\nforegrounds.", "positive": "The Gaia-ESO survey: the non-universality of the\n age-chemical-clocks-metallicity relations in the Galactic disc: In the era of large spectroscopic surveys, massive databases of high-quality\nspectra provide tools to outline a new picture of our Galaxy. In this\nframework, an important piece of information is provided by our ability to\ninfer stellar ages. We aim to provide empirical relations between stellar ages\nand abundance ratios for a sample of solar-like stars. We investigate the\ndependence on metallicity, and we apply our relations to Gaia-ESO samples of\nopen clusters and field stars. We analyse high-resolution and high-S/N HARPS\nspectra of a sample of solar-like stars to obtain precise determinations of\ntheir atmospheric parameters and abundances through differential spectral\nanalysis and age through isochrone fitting. We investigate the relations\nbetween ages and abundance ratios. For the abundance ratios with a steeper\ndependence on age, we perform multivariate linear regressions, including the\ndependence on metallicity. We apply our relations to a sample of open clusters\nlocated in 47 kpc. In these clusters, the\ncontent of s-elements is lower than expected from chemical evolution models,\nand consequently the [s/$\\alpha$] are lower than in clusters of the same age\nlocated in the solar neighbourhood. With our chemical evolution model and a set\nof empirical yields, we suggest that a strong dependence on the star formation\nhistory and metallicity-dependent yields of s-elements can substantially modify\nthe slope of the [s/$\\alpha$]-[Fe/H]-age relation in different regions of the\nGalaxy. Our results point towards a non-universal relation\n[s/$\\alpha$]-[Fe/H]-age, indicating the existence of relations at different\nR$_{GC}$ or for different star formation history. A better understanding of the\ns-process at high metallicity is necessary to fully understand the origin of\nthese variations." }, { "anchor": "A panoptic view of the Taurus molecular cloud I. The cloud dynamics\n revealed by gas emission and 3D dust: We present a study of the three-dimensional (3D) distribution of interstellar\ndust derived from stellar extinction observations toward the Taurus molecular\ncloud (MC) and its relation with the neutral atomic hydrogen (HI) emission at\n21 cm wavelength and the carbon monoxide $^{12}$CO and $^{13}$CO emission in\nthe $J=1\\rightarrow0$ transition. We used the histogram of oriented gradients\n(HOG) method to match the morphology in a 3D reconstruction of the dust density\n(3D dust) and the distribution of the gas tracers' emission. The result of the\nHOG analysis is a map of the relationship between the distances and radial\nvelocities. The HOG comparison between the 3D dust and the HI emission\nindicates a morphological match at the distance of Taurus but an\nanti-correlation between the dust density and the HI emission, which uncovers a\nsignificant amount of cold HI within the Taurus MC. The HOG between the 3D dust\nand $^{12}$CO reveals a pattern in radial velocities and distances that is\nconsistent with converging motions of the gas in the Taurus MC, with the near\nside of the cloud moving at higher velocities and the far side moving at lower\nvelocities. This convergence of flows is likely triggered by the large-scale\ngas compression caused by the interaction of the Local Bubble and the Per-Tau\nshell, with Taurus lying at the intersection of the two bubble surfaces.", "positive": "HII versus HI in the `green valley' galaxies: direct comparison: We study the morphology and kinematics of the ionization state of the gas in\nfour 'green valley' early-type galaxies at different stages of their transition\nfrom a 'blue cloud' of star-forming galaxies to the sequence of passive\nevolution. The previous HI mapping of the considered sample reveals a spatial\noffset between the cold gas reservoirs and stellar discs depending on the\npost-starburst age. Consideration of the ionized-gas properties is essential to\nunderstand the role of various feedback processes in star formation quenching.\nWe performed long-slit and 3D optical spectroscopic observations at the 6-m\nRussian telescope and compared the gas and stellar kinematics. Spatial\ndistribution of the ionized gas is in agreement with HI maps; however, the\none-order higher angular resolution in the HII velocity fields allows us to\nstudy non-circular gas motions in detail, like the AGN-driven outflow in the\nnucleus of J1117+51. The most intriguing result is the global HI+HII gas\ncounter-rotation relative to the stellar disc in J1237+39. Therefore, in this\ncase all the observed gas in the 'green valley' galaxy was captured from the\nenvironment via accretion or minor merging." }, { "anchor": "The Effect of Filaments and Tendrils on the HI Content of Galaxies: We use the ALFALFA HI survey to examine whether the cold gas reservoirs of\ngalaxies are inhibited or enhanced in large-scale filaments. Our sample\nincludes 9947 late-type galaxies with HI detections, and 4236 late-type\ngalaxies with well-determined HI detection limits that we incorporate using\nsurvival analysis statistics. We find that, even at fixed local density and\nstellar mass, and with group galaxies removed, the HI deficiency of galaxies in\nthe stellar mass range 8.5 2$. This is due to the strong dust attenuation common in massive galaxies at\nthe epoch and the scarcity of high-resolution, high-sensitivity\nextinction-independent imaging. To search for disk substructures, we subtracted\nthe central stellar-mass disk from the JWST/NIRCam rest-frame 1.2 $\\mu$m image\n($0.13''$ resolution) and subtracted, in the visibility plane, the central\nstarburst disk from ALMA rest-frame 240 $\\mu$m observations ($0.03''$\nresolution). The residual images revealed substructures at rest-frame 1.2\n$\\mu$m co-located with those found at rest-frame 240 $\\mu$m, $\\simeq 2$ kpc\naway from the galactic center. The largest substructure contains $\\simeq20$% of\nthe total stellar mass and $\\simeq5$% of the total SFR of the galaxy. While\nUDF2 exhibits a kinematically-ordered velocity field of molecular gas\nconsistent with a secularly evolving disk, more sensitive observations are\nrequired to characterize the nature and the origin of this substructure (spiral\narms, minor merger, or other types of disk instabilities). UDF2 resides in an\noverdense region ($N \\geqslant 4$ massive galaxies within 70 kpc projected\ndistance at $z=2.690-2.697$) and the substructures may be associated with\ninteraction-induced instabilities. Importantly, a statistical sample of such\nsubstructures identified with JWST and ALMA could play a key role in bridging\nthe gap between the bulge-forming starburst and the rest of the galaxy.", "positive": "Discovery of three new pulsars in a 610 MHz pulsar survey with the GMRT: We report on the discovery of three new pulsars in the first blind survey of\nthe north Galactic plane (45 degrees < l < 135 degrees; |b| < 1 degrees with\nthe Giant Meterwave Radio telescope (GMRT) at an intermediate frequency of 610\nMHz. The survey covered 106 square degrees with a sensitivity of roughly 1 mJy\nto long-period pulsars (pulsars with period longer than 1 s). The three new\npulsars have periods of 318, 933, and 1056 ms. Their timing parameters and flux\ndensities, obtained in follow up observations with the Lovell Telescope at\nJodrell Bank and the GMRT, are presented. We also report on pulse nulling\nbehaviour in one of the newly discovered pulsars, PSR J2208+5500." }, { "anchor": "Observability of pulsar beam bending by the Sgr~A* black hole: According to some models, there may be a significant population of radio\npulsars in the Galactic center. In principle, a beam from one of these pulsars\ncould pass close to the supermassive black hole (SMBH) at the center, be\ndeflected, and be detected by Earth telescopes. Such a configuration would be\nan unprecedented probe of the properties of spacetime in the moderate- to\nstrong-field regime of the SMBH. We present here background on the problem, and\napproximations for the probability of detection of such beams. We conclude that\ndetection is marginally probable with current telescopes, but that telescopes\nthat will be operating in the near future, with an appropriate multiyear\nobservational program, will have a good chance of detecting a beam deflected by\nthe SMBH.", "positive": "Properties of Hi-GAL clumps in the inner Galaxy]{The Hi-GAL compact\n source catalogue. I. The physical properties of the clumps in the inner\n Galaxy ($-71.0^{\\circ}< \\ell < 67.0^{\\circ}$): Hi-GAL is a large-scale survey of the Galactic plane, performed with Herschel\nin five infrared continuum bands between 70 and 500 $\\mu$m. We present a\nband-merged catalogue of spatially matched sources and their properties derived\nfrom fits to the spectral energy distributions (SEDs) and heliocentric\ndistances, based on the photometric catalogs presented in Molinari et al.\n(2016a), covering the portion of Galactic plane $-71.0^{\\circ}< \\ell <\n67.0^{\\circ}$. The band-merged catalogue contains 100922 sources with a regular\nSED, 24584 of which show a 70 $\\mu$m counterpart and are thus considered\nproto-stellar, while the remainder are considered starless. Thanks to this huge\nnumber of sources, we are able to carry out a preliminary analysis of early\nstages of star formation, identifying the conditions that characterise\ndifferent evolutionary phases on a statistically significant basis. We\ncalculate surface densities to investigate the gravitational stability of\nclumps and their potential to form massive stars. We also explore evolutionary\nstatus metrics such as the dust temperature, luminosity and bolometric\ntemperature, finding that these are higher in proto-stellar sources compared to\npre-stellar ones. The surface density of sources follows an increasing trend as\nthey evolve from pre-stellar to proto-stellar, but then it is found to decrease\nagain in the majority of the most evolved clumps. Finally, we study the\nphysical parameters of sources with respect to Galactic longitude and the\nassociation with spiral arms, finding only minor or no differences between the\naverage evolutionary status of sources in the fourth and first Galactic\nquadrants, or between \"on-arm\" and \"inter-arm\" positions." }, { "anchor": "Molecular ion abundances in the diffuse ISM : CF+, HCO+, HOC+, and C3H+: The transition between atomic and molecular hydrogen is associated with\nimportant changes in the structure of interstellar clouds, and marks the\nbeginning of interstellar chemistry. Because of the relatively simple networks\ncontrolling their abundances, molecular ions are usually good probes of the\nunderlying physical conditions including for instance the fraction of gas in\nmolecular form or the fractional ionization. In this paper we focus on three\npossible probes of the molecular hydrogen column density, HCO+, HOC+, and CF+.\nWe presented high sensitivity ALMA absorption data toward a sample of compact\nHII regions and bright QSOs with prominent foreground absorption, in the ground\nstate transitions of the molecular ions HCO+, HOC+, and CF+ and the neutral\nspecies HCN and HNC, and from the excited state transitions of C3H+(4-3) and\n13CS(2-1). These data are compared with Herschel absorption spectra of the\nground state transition of HF and p-H2O. We show that the HCO+, HOC+, and CF+\ncolumn densities are well correlated with each other. HCO+ and HOC+ are tightly\ncorrelated with p-H2O, while they exhibit a different correlation pattern with\nHF depending on whether the absorbing matter is located in the Galactic disk or\nin the central molecular zone. We report new detections of C3H+ confirming that\nthis ion is ubiquitous in the diffuse matter, with an abundance relative to H2\nof ~7E-11. We confirm that the CF+ abundance is lower than predicted by simple\nchemical models and propose that the rate of the main formation reaction is\nlower by a factor of about 3 than usually assumed. In the absence of CH or HF\ndata, we recommend to use the ground state transitions of HCO+, CCH, and HOC+\nto trace diffuse molecular hydrogen, with mean abundances relative to H2 of\n3E-9, 4E-8 and 4E-11.", "positive": "A Census of Early Phase High-Mass Star Formation in the Central\n Molecular Zone: We present new observations of C-band continuum emission and masers to assess\nhigh-mass ($>$8 $M_\\odot$) star formation at early evolutionary phases in the\ninner 200 pc of the Central Molecular Zone (CMZ) of the Galaxy. The continuum\nobservation is complete to free-free emission from stars above 10-11 $M_\\odot$\nin 91% of the covered area. We identify 104 compact sources in the continuum\nemission, among which five are confirmed ultracompact H II regions, 12 are\ncandidates of ultra-compact H II regions, and the remaining 87 sources are\nmostly massive stars in clusters, field stars, evolved stars, pulsars,\nextragalactic sources, or of unknown nature that is to be investigated. We\ndetect class II CH$_3$OH masers at 23 positions, among which six are new\ndetections. We confirm six known H$_2$CO masers in two high-mass star forming\nregions, and detect two new H$_2$CO masers toward the Sgr C cloud, making it\nthe ninth region in the Galaxy that contains masers of this type. In spite of\nthese detections, we find that current high-mass star formation in the inner\nCMZ is only taking place in seven isolated clouds. The results suggest that\nstar formation at early evolutionary phases in the CMZ is about 10 times less\nefficient than expected by the dense gas star formation relation, which is in\nline with previous studies that focus on more evolved phases of star formation.\nThis means that if there will be any impending, next burst of star formation in\nthe CMZ, it has not yet begun." }, { "anchor": "Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes). IV.\n Ultra-Diffuse Satellites of Milky Way Analogs: To better understand the formation of large, low surface brightness galaxies,\nwe measure the correlation function between ultra-diffuse galaxy (UDG)\ncandidates and Milky Way analogs (MWAs). We find that (1) the projected radial\ndistribution of UDG satellites (projected surface density $\\propto\nr^{-0.84\\pm0.06}$) is consistent with that of normal satellite galaxies, (2)\nthe number of UDG satellites per MWA ($S_{\\rm UDG}$) is $\\sim 0.5\\pm0.1$ over\nprojected radii from 20 to 250 kpc and $-17< M_r < -13.5$, (3) $S_{\\rm UDG}$ is\nconsistent with a linear extrapolation of the relationship between the number\nof UDGs per halo vs. halo mass obtained over galaxy group and cluster scales,\n(4) red UDG satellites dominate the population of UDG satellites ($\\sim80$%),\n(5) over the range of satellite magnitudes studied, UDG satellites comprise\n$\\sim$ 10% of the satellite galaxy population of MWAs, (6) a significant\nfraction of these ($\\sim$13%) have estimated total masses $>$ 10$^{10.9}$\nM$_\\odot$ or, equivalently, at least half the halo mass of the LMC, and\npopulate a large fraction ($\\sim$ 18%) of the expected subhalos down to these\nmasses. All of these results suggest a close association between the overall\nlow mass galaxy population and UDGs, which we interpret as favoring models\nwhere UDG formation principally occurs within the general context of low mass\ngalaxy formation over models invoking more exotic physical processes\nspecifically invoked to form UDGs.", "positive": "Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). XVI. 69\n New Quasars at 5.8 < z < 7.0: We present the spectroscopic discovery of 69 quasars at 5.8 < z < 7.0, drawn\nfrom the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) imaging survey\ndata. This is the 16th publication from the Subaru High-z Exploration of\nLow-Luminosity Quasars (SHELLQs) project, and completes identification of all\nbut the faintest candidates (i.e., i-band dropouts with zAB < 24 and y-band\ndetections, and z-band dropouts with yAB < 24) with Bayesian quasar probability\nPq > 0.1 in the HSC-SSP third public data release (PDR3). The sample reported\nhere also includes three quasars with Pq < 0.1 at z ~ 6.6, which we selected in\nan effort to completely cover the reddest point sources with simple color cuts.\nThe number of high-z quasars discovered in SHELLQs has now grown to 162,\nincluding 23 type-II quasar candidates. This paper also presents identification\nof seven galaxies at 5.6 < z < 6.7, an [O III] emitter at z = 0.954, and 31\nGalactic cool stars and brown dwarfs. High-z quasars and galaxies comprise 75 %\nand 16 % respectively of all the spectroscopic SHELLQs objects that pass our\nlatest selection algorithm with the PDR3 photometry. That is, a total of 91 %\nof the objects lie at z > 5.6. This demonstrates that the algorithm has very\nhigh efficiency, even though we are probing an unprecedentedly low-luminosity\npopulation down to M1450 ~ -21 mag." }, { "anchor": "Portrait of a Dark Horse: a Photometric and Spectroscopic Study of the\n Ultra-faint Milky Way Satellite Pegasus III: Pegasus III (Peg III) is one of the few known ultra-faint stellar systems in\nthe outer halo of the Milky Way. We present the results from a follow-up\ncampaign with Magellan/IMACS and Keck/DEIMOS. Deep stellar photometry down to\n$r_0\\approx 25$ mag at 50% completeness level has allowed accurate measurements\nof its photometric and structural properties. The color-magnitude diagram of\nPeg III confirms that the stellar system is well described by an old\n($\\gtrsim12$ Gyr) and metal-poor ([Fe/H]$\\lesssim-2.0$ dex) stellar population\nat a heliocentric distance of $215\\pm12$ kpc. The revised half-light radius\n$r_{h}=53\\pm14$ pc, ellipticity $\\epsilon=0.38^{+0.22}_{-0.38}$, and total\nluminosity $M_{V}=-3.4\\pm0.4$ are in good agreement with the values quoted in\nour previous paper. We further report on the spectroscopic identification of\nseven, possibly eight member stars of Peg III. The Ca II triplet lines of the\nbrightest member stars indicate that Peg III contains stars with metallicity as\nlow as [Fe/H]=$-2.55\\pm0.15$ dex. Peg III has a systemic velocity of $-222.9\n\\pm 2.6$ km s$^{-1}$ and a velocity dispersion of $5.4^{+3.0}_{-2.5}$ km\ns$^{-1}$. The inferred dynamical mass within the half-light radius is\n$1.4^{+3.0}_{-1.1} \\times 10^6\\rm{M_{\\odot}}$ and the mass-to-light ratio\n$\\rm{M/L}$$_{V} = 1470^{+5660}_{-1240}$ $\\rm{M_{\\odot}/L_{\\odot}}$, providing\nfurther evidence that Peg III is a dwarf galaxy satellite. We find that Peg III\nand another distant dwarf satellite Pisces II lie relatively close to each\nother ($\\Delta d_{spatial}=43\\pm19$ kpc) and share similar radial velocities in\nthe Galactic standard-of-rest frame ($\\Delta v_{GSR}=12.3\\pm3.7$ km s$^{-1}$).\nThis suggests that they may share a common origin.", "positive": "Gas-phase Elemental abundances in Molecular cloudS (GEMS) III. Unlocking\n the CS chemistry: the CS+O reaction: CS is among the most abundant gas-phase S-bearing molecules in cold dark\nmolecular clouds. It is easily observable with several transitions in the\nmillimeter wavelength range, and has been widely used as a tracer of the gas\ndensity in the interstellar medium in our Galaxy and external galaxies.\nChemical models fail to account for the observed CS abundances when assuming\nthe cosmic value for the elemental abundance of sulfur. The CS+O -> CO + S\nreaction has been proposed as a relevant CS destruction mechanism at low\ntemperatures, and could explain the discrepancy between models and\nobservations. Its reaction rate has been experimentally measured at\ntemperatures of 150-400 K, but the extrapolation to lower temperatures is\ndoubtful. Here we calculate the CS+O reaction rate at temperatures <150 K which\nare prevailing in the interstellar medium. We performed ab initio calculations\nto obtain the three lowest PES of the CS+O system. These PESs are used to study\nthe reaction dynamics, using several methods to eventually calculate the CS+O\nthermal reaction rates. We compare the results of our theoretical calculations\nfor 150-400 K with those obtained in the laboratory. Our detailed theoretical\nstudy on the CS+O reaction, which is in agreement with the experimental data\nobtained at 150-400 K, demonstrates the reliability of our approach. After a\ncareful analysis at lower temperatures, we find that the rate constant at 10 K\nis negligible, which is consistent with the extrapolation of experimental data\nusing the Arrhenius expression. We use the updated chemical network to model\nthe sulfur chemistry in TMC1 based on molecular abundances determined from GEMS\nproject observations. In our model, we take into account the expected decrease\nof the cosmic ray ionization rate along the cloud. The abundance of CS is still\noverestimated when assuming the cosmic value for the sulfur abundance." }, { "anchor": "Circumgalactic Oxygen Absorption and Feedback: OVI absorption in quasar spectra caused by intervening circumgalactic\natmospheres suggests a downturn in the atmospheric column density in sightlines\npassing beyond about 100 kpc from central star-forming galaxies. This turnover\nsupports the hypothesis that the oxygen originates in the central galaxies.\nWhen converted into oxygen space density using an Abel integral inversion, the\nOVI columns require greater than $\\approx 10^9 M_\\odot$ of oxygen concentrated\nnear 100 kpc. Circumgalactic gas within this radius cools in less than 1 Gyr\nand radiates $\\sim 10^{42.2}$ erg s$^{-1}$ overall. The feedback power\nnecessary to maintain such oxygen-rich atmospheres for many Gyrs cannot be\neasily supplied by galactic supernovae. However, massive central black holes in\nstar-forming galaxies may generate sufficient accretion power and intermittent\nshock waves at $r \\sim 100$ kpc to balance circumgalactic radiation losses in\nlate-type $L^\\star$ galaxies. The relative absence of OVI absorption observed\nin early-type, passive $L^{\\star}$ galaxies may arise from enhanced AGN\nfeedback from their more massive central black holes.", "positive": "Small-scale dynamo with finite correlation times: Fluctuation dynamos occur in most turbulent plasmas in astrophysics and are\nthe prime candidates for amplifying and maintaining cosmic magnetic fields. A\nfew analytical models exist to describe their behaviour but they are based on\nsimplifying assumptions. For instance the well-known Kazantsev model assumes an\nincompressible flow that is delta-correlated in time. However, these\nassumptions can break down in the interstellar medium as it is highly\ncompressible and the velocity field has a finite correlation time. Using the\nrenewing flow method developed by Bhat and Subramanian (2014), we aim to extend\nKazantsev's results to a more general class of turbulent flows. The cumulative\neffect of both compressibility and finite correlation time over the Kazantsev\nspectrum is studied analytically. We derive an equation for the longitudinal\ntwo-point magnetic correlation function in real space to first order in the\ncorrelation time $\\tau$ and for an arbitrary degree of compressibility (DOC).\nThis generalised Kazantsev equation encapsulates the original Kazantsev\nequation. In the limit of small Strouhal numbers $St \\propto \\tau$ we use the\nWKB approximation to derive the growth rate and scaling of the magnetic power\nspectrum. We find the result that the Kazantsev spectrum is preserved, i.e.\n$M_k(k)\\sim k^{3/2}$. The growth rate is also negligibly affected by the finite\ncorrelation time; however, it is reduced by the finite magnetic diffusivity,\nand the DOC together." }, { "anchor": "Near-Infrared Photometric Survey of Herbig Ae/Be Candidate Stars: We report near-infrared photometric measurements of 35 Herbig Ae/Be candidate\nstars obtained with direct imaging and aperture photometry. Observations were\nmade through the broadband J, H, and K' filters, with each source imaged in at\nleast one of the wavebands. We achieved subarcsecond angular resolution for all\nobservations, providing us with the opportunity to search for close binary\ncandidates and extended structure. The imaging revealed five newly identified\nbinary candidates and one previously resolved T Tauri binary among the target\nsources with separations of <~2.5\". Separate photometry is provided for each of\nthe binary candidate stars. We detect one extended source that has been\nidentified as a protoplanetary nebula. Comparing our magnitudes to past\nmeasurements yields significant differences for some sources, possibly\nindicating photometric variability. H-band finding charts for all of our\nsources are provided to aid follow-up high-resolution imaging.", "positive": "Hot Dust-Obscured Galaxies with Excess Blue Light: Hot Dust-Obscured Galaxies (Hot DOGs) are among the most luminous galaxies in\nthe Universe. Powered by highly obscured, possibly Compton-thick, active\ngalactic nuclei (AGNs), Hot DOGs are characterized by SEDs that are very red in\nthe mid-IR yet dominated by the host galaxy stellar emission in the UV and\noptical. An earlier study identified a sub-sample of Hot DOGs with\nsignificantly enhanced UV emission. One target, W0204-0506, was studied in\ndetail and, based on Chandra observations, it was concluded that the enhanced\nemission was most likely due to either extreme unobscured star-formation (${\\rm\nSFR}>1000~M_{\\odot}~\\rm yr^{-1}$) or to light from the highly obscured AGN\nscattered by gas or dust into our line of sight. Here, we present a follow-up\nstudy of W0204-0506 as well as two more Hot DOGs with excess UV emission. For\nthe two new objects we obtained Chandra/ACIS-S observations, and for all three\ntargets we obtained HST/WFC3 F555W and F160W imaging. We conclude that the\nexcess UV emission is primarily dominated by light from the central highly\nobscured, hyper-luminous AGN that has been scattered into our line of sight. We\ncannot rule out, however, that star-formation may significantly contribute to\nthe UV excess of W0204-0506." }, { "anchor": "Molecular hydrogen in IllustrisTNG galaxies: carefully comparing\n signatures of environment with local CO & SFR data: We examine how the post-processed content of molecular hydrogen (H$_2$) in\ngalaxies from the TNG100 cosmological, hydrodynamic simulation changes with\nenvironment at $z\\!=\\!0$, assessing central/satellite status and host halo\nmass. We make close comparisons with the carbon monoxide (CO) emission survey\nxCOLD GASS where possible, having mock-observed TNG100 galaxies to match the\nsurvey's specifications. For a representative sample of host haloes across\n$10^{11}\\!\\lesssim\\!M_{\\rm 200c}/{\\rm M}_{\\odot}\\!<\\!10^{14.6}$, TNG100\npredicts that satellites with $m_*\\!\\geq\\!10^9\\,{\\rm M}_{\\odot}$ should have a\nmedian deficit in their H$_2$ fractions of $\\sim$0.6 dex relative to centrals\nof the same stellar mass. Once observational and group-finding uncertainties\nare accounted for, the signature of this deficit decreases to $\\sim$0.2 dex.\nRemarkably, we calculate a deficit in xCOLD GASS satellites' H$_2$ content\nrelative to centrals of 0.2--0.3 dex, in line with our prediction. We further\nshow that TNG100 and SDSS data exhibit continuous declines in the average star\nformation rates of galaxies at fixed stellar mass in denser environments, in\nquantitative agreement with each other. By tracking satellites from their\nmoment of infall in TNG100, we directly show that atomic hydrogen (HI) is\ndepleted at fractionally higher rates than H$_2$ on average. Supporting this\npicture, we find that the H$_2$/HI mass ratios of satellites are elevated\nrelative to centrals in xCOLD GASS. We provide additional predictions for the\neffect of environment on H$_2$ -- both absolute and relative to HI -- that can\nbe tested with spectral stacking in future CO surveys.", "positive": "Modeling the molecular gas content and CO-to-H2 conversion factors in\n low-metallicity star-forming dwarf galaxies: Low-metallicity dwarf galaxies often show no or little CO emission, despite\nthe intense star formation observed in local samples. Both simulations and\nresolved observations indicate that molecular gas in low-metallicity galaxies\nmay reside in small dense clumps, surrounded by a substantial amount of more\ndiffuse gas, not traced by CO. Constraining the relative importance of\nCO-bright versus CO-dark H2 star-forming reservoirs is crucial to understand\nhow star formation proceeds at low metallicity. We put to the test classically\nused single component radiative transfer models and compare their results to\nthose obtained assuming an increasingly complex structure of the interstellar\ngas, mimicking an inhomogeneous distribution of clouds with various physical\nproperties. We compute representative models of the interstellar medium as\ncombinations of several gas components, each with a specific set of physical\nparameters. We introduce physically-motivated models assuming power-law\ndistributions for the density, ionization parameter, and the depth of molecular\nclouds. We confirm the presence of a predominantly CO-dark molecular reservoir\nin low-metallicity galaxies. The predicted total H2 mass is best traced by [C\nII]158um and, to a lesser extent, by [CI] 609um, rather than by CO(1-0). We\nexamine the CO-to-H2 conversion factor vs. metallicity relation and find that\nits dispersion increases significantly when different geometries of the gas are\nconsidered. We define a clumpiness parameter that anti-correlates with [CII]/CO\nand explains the dispersion of the CO-to-H2 conversion factor vs. metallicity\nrelation. We find that low-metallicity galaxies with high clumpiness may have\nCO-to-H2 conversion factor as low as the Galactic value. We identify the\nclumpiness of molecular gas as a key parameter to understand variations of\ngeometry-sensitive quantities, such as CO-to-H2 conversion factor." }, { "anchor": "Newly Identified Star Clusters in M33. III. Structural Parameters: We present the morphological properties of 161 star clusters in M33 using the\nAdvanced Camera For Surveys Wide Field Channel onboard the Hubble Space\nTelescope using observations with the F606W and F814W filters. We obtain, for\nthe first time, ellipticities, position angles, and surface brightness profiles\nfor a significant number of clusters. On average, M33 clusters are more\nflattened than those of the Milky Way and M31, and more similar to clusters in\nthe Small Magellanic Cloud. The ellipticities do not show any correlation with\nage or mass, suggesting that rotation is not the main cause of elongation in\nthe M33 clusters. The position angles of the clusters show a bimodality with a\nstrong peak perpendicular to the position angle of the galaxy major axis. These\nresults support the notion that tidal forces are the reason for the cluster\nflattening. We fit King and EFF models to the surface brightness profiles and\nderive structural parameters including core radii, concentration, half-light\nradii and central surface brightness for both filters. The surface brightness\nprofiles of a significant number of clusters show irregularities such as bumps\nand dips. Young clusters (Log age < 8) are notably better fitted by models with\nno radial truncation (EFF models), while older clusters show no significant\ndifferences between King or EFF fits. M33 star clusters seem to have smaller\nsizes, smaller concentrations, and smaller central surface brightness as\ncompared to clusters in the MW, M31, LMC and SMC. Analysis of the structural\nparameters presents a age-radius relation also detected in other star cluster\nsystems. The overall analysis shows differences in the structural evolution\nbetween the M33 cluster system and cluster systems in nearby galaxies. These\ndifferences could have been caused by the strong differences in these various\nenvironments.", "positive": "An accurate strong lensing model of the Abell 2163 core: Abell 2163 at $z \\simeq 0.201$ is one of the most massive galaxy clusters\nknown, very likely in a post-merging phase. Data from several observational\nwindows suggest a complex mass structure with interacting subsystems, which\nmakes the reconstruction of a realistic merging scenario very difficult. A\nmissing key element in this sense is unveiling the cluster mass distribution at\nhigh resolution. We perform such a reconstruction of the cluster inner total\nmass through a strong lensing model based on new spectroscopic redshift\nmeasurements. We use data from the Multi Unit Spectroscopic Explorer (MUSE) on\nthe Very Large Telescope (VLT) to confirm 12 multiple images of 4 sources with\nredshift values from 1.16 to 2.72. We also discover four new multiple images\nand identify 29 cluster members and 35 foreground and background sources. The\nresulting galaxy member and image catalogs are used to build five cluster total\nmass models. The fiducial model consists of 111 small-scale subhalos plus a\ndiffuse component, which is centered $\\sim2$ arcseconds away from the BCG\nbelonging to the east Abell 2163 subcluster. We confirm that the latter is well\nrepresented by a single, large-scale mass component. Its strong elongation\ntowards a second (west) subcluster confirms the existence of a preferential\naxis, corresponding to the merging direction. From the fiducial model, we\nextrapolate the cumulative projected total mass profile and measure a value of\n$M(<300\\,$kpc$) = 1.43^{+0.07}_{-0.06}\\times 10^{14}\\,$M$_{\\odot}$, which has a\nsignificantly reduced statistical error compared with previous estimates,\nthanks to the inclusion of the spectroscopic redshifts. Our strong lensing\nresults are very accurate: the model-predicted positions of the multiple images\nare, on average, only $0.15$ arcseconds away from the observed ones." }, { "anchor": "Stellar Masses and SFRs for 1M Galaxies from SDSS and WISE: We combine SDSS and WISE photometry for the full SDSS spectroscopic galaxy\nsample, creating SEDs that cover lambda=0.4-22 micron for an unprecedented\nlarge and comprehensive sample of 858,365 present-epoch galaxies. Using MAGPHYS\nwe then model simultaneously and consistently both the attenuated stellar SED\nand the dust emission at 12 micron and 22 micron, producing robust new\ncalibrations for monochromatic mid-IR star formation rate proxies. These\nmodeling results provide the first mid-IR-based view of the bi-modality in star\nformation activity among galaxies, exhibiting the sequence of star-forming\ngalaxies (main sequence) with a slope of dlogSFR/dlogM*=0.80 and a scatter of\n0.39 dex. We find that these new star-formation rates along the SF main\nsequence are systematically lower by a factor of 1.4 than those derived from\noptical spectroscopy. We show that for most present-day galaxies the 0.4-22\nmicron SED fits can exquisitely predict the fluxes measured by Herschel at much\nlonger wavelengths. Our analysis also illustrates that the majorities of stars\nin the present-day universe is formed in luminous galaxies (~L*) in and around\nthe green valley of the color-luminosity plane. We make the matched photometry\ncatalog and SED modeling results publicly available.", "positive": "AGN feedback in dwarf galaxies?: Dwarf galaxy anomalies, such as their abundance and cusp-core problems,\nremain a prime challenge in our understanding of galaxy formation. The\ninclusion of baryonic physics could potentially solve these issues, but the\nefficiency of stellar feedback is still controversial. We analytically explore\nthe possibility of feedback from Active Galactic Nuclei (AGN) in dwarf galaxies\nand compare AGN and supernova (SN) feedback. We assume the presence of an\nintermediate mass black hole within low mass galaxies and standard scaling\nrelations between the relevant physical quantities. We model the propagation\nand properties of the outflow and explore the critical condition for global gas\nejection. Performing the same calculation for SNe, we compare the ability of\nAGN and SNe to drive gas out of galaxies. We find that a critical halo mass\nexists below which AGN feedback can remove gas from the host halo and that the\ncritical halo mass for AGN is greater than the equivalent for SNe in a\nsignificant part of the parameter space, suggesting that AGN could provide an\nalternative and more successful source of negative feedback than SNe, even in\nthe most massive dwarf galaxies." }, { "anchor": "The MURALES survey. I. A dual AGN in the radio galaxy 3C459?: We observed the FRII radio galaxy 3C459 (z=0.22) with the MUSE spectrograph\nat the Very Large Telescope (VLT) as part of the MURALES project (a MUse RAdio\nLoud Emission line Snapshot survey). We detected diffuse nuclear emission and a\nfilamentary ionized gas structure forming a one-sided, triangular-shaped region\nextending out to $\\sim$80 kpc. The central emission line region is dominated by\ntwo compact knots of similar flux: the first (N1) cospatial with the radio core\nand the (N2) second located 1.2\" (5.3 kpc) to the SE. The two regions differ\ndramatically from the point of view of velocity (with an offset of ~400 km/s),\nline widths, and line ratios. This suggests that we are observing a dual AGN\nsystem formed by a radio loud AGN and type 2 QSO companion, which is the result\nof the recent merger that also produced its disturbed host morphology. The\nalternative possibility that N2 is just a bright emission line knot resulting\nfrom, for example, a jet-cloud interaction, is disfavored because of 1) the\npresence of a high ionization bicone whose apex is located at N2; 2) the\nobserved narrow line widths; 3) its line luminosity (~10^42 erg s-1) typical of\nluminous QSOs; and 4) its location, which is offset from the jet path. The\nputative secondary AGN must be highly obscured, since we do not detect any\nemission in the Chandra and infrared Hubble Space Telescope images.", "positive": "Full spectrum fitting with photometry in pPXF: stellar population versus\n dynamical masses, non-parametric star formation history and metallicity for\n 3200 LEGA-C galaxies at redshift z~0.8: I introduce some improvements to the pPXF method, which measures the stellar\nand gas kinematics, star formation history (SFH) and chemical composition of\ngalaxies. I describe the new optimization algorithm that pPXF uses and the\nchanges I made to fit both spectra and photometry simultaneously. I apply the\nupdated pPXF method to a sample of 3200 galaxies at redshift $0.63\\times10^{10}$ M$_\\odot$), using spectroscopy\nfrom the LEGA-C survey (DR3) and 28-bands photometry from two different\nsources. I compare the masses from new JAM dynamical models with the pPXF\nstellar population $M_\\ast$ and show the latter are more reliable than previous\nestimates. I use three different stellar population synthesis (SPS) models in\npPXF and both photometric sources. I confirm the main trend of the galaxies'\nglobal ages and metallicity $[M/H]$ with stellar velocity dispersion\n$\\sigma_\\ast$ (or central density), but I also find that $[M/H]$ depends on age\nat fixed $\\sigma_\\ast$. The SFHs reveal a sharp transition from star formation\nto quenching for galaxies with $\\lg(\\sigma_\\ast/\\mathrm{km\\, s^{-1}})>2.3$, or\naverage mass density within 1 kpc $\\lg(\\Sigma_1^{\\rm JAM}/\\mathrm{M_\\odot\nkpc^{-2}})>9.9$, or with $[M/H]>-0.1$, or with Sersic index $\\lg n_{\\rm\nSer}>0.5$. However, the transition is smoother as a function of $M_\\ast$. These\nresults are consistent for two SPS models and both photometric sources, but\nthey differ significantly from the third SPS model, which demonstrates the\nimportance of comparing model assumptions. The pPXF software is available from\nhttps://pypi.org/project/ppxf/." }, { "anchor": "Braginskii viscosity on an unstructured, moving mesh accelerated with\n super-time-stepping: We present a method for efficiently modelling Braginskii viscosity on an\nunstructured, moving mesh. Braginskii viscosity, i.e., anisotropic transport of\nmomentum with respect to the direction of the magnetic field, is thought to be\nof prime importance for studies of the weakly collisional plasma that comprises\nthe intracluster medium (ICM) of galaxy clusters. Here anisotropic transport of\nheat and momentum has been shown to have profound consequences for the\nstability properties of the ICM. Our new method for modelling Braginskii\nviscosity has been implemented in the moving mesh code Arepo. We present a\nnumber of examples that serve to test the implementation and illustrate the\nmodified dynamics found when including Braginskii viscosity in simulations.\nThese include (but are not limited to) damping of fast magneto-sonic waves,\ninterruption of linearly polarized Alfv\\'en waves by the firehose instability\nand the inhibition of the Kelvin-Helmholtz instability by Braginskii viscosity.\nAn explicit update of Braginskii viscosity is associated with a severe time\nstep constraint that scales with $(\\Delta x)^2$ where $\\Delta x$ is the grid\nsize. In our implementation, this restrictive time step constraint is\nalleviated by employing 2nd order accurate Runge-Kutta-Legendre\nsuper-time-stepping. We envision including Braginskii viscosity in future\nlarge-scale simulations of Kelvin-Helmholtz unstable cold fronts in cluster\nmergers and AGN-generated bubbles in central cluster regions.", "positive": "Extremely red galaxies at $z=5-9$ with MIRI and NIRSpec: dusty galaxies\n or obscured AGNs?: We study a new population of extremely red objects (EROs) recently discovered\nby JWST based on their NIRCam colors F277W$-$F444W $>1.5$ mag. We find 37 EROs\nin the CEERS field with F444W $<28$ mag and photometric redshifts between\n$57$ by up to a factor $\\sim$60. Similarly, if\nthey are OSOs with luminosities in the L$_{\\rm bol}>10^{46-47}$ erg s$^{-1}$\nrange, their number would exceed that of bright blue QSOs by more than two\norders of magnitude. Additional photometry at mid-IR wavelengths will reveal\nthe true nature of the red continuum emission in these EROs and will place this\npuzzling population in the right context of galaxy evolution." }, { "anchor": "The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in\n the Southern Galactic Cap I. The Spectroscopic Redshift Catalog: We present a spectroscopic redshift catalog from the LAMOST Complete\nSpectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap\n(SGC), which is designed to observe all sources (Galactic and extra-galactic)\nby using repeating observations with a limiting magnitude of $r=18.1~mag$ in\ntwo $20~deg^2$ fields. The project is mainly focusing on the completeness of\nLAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source\nselection methods and the basic performance parameters of LAMOST telescope. In\nboth fields, more than 95% of galaxies have been observed. A post-processing\nhas been applied to LAMOST 1D spectrum to remove the majority of remaining sky\nbackground residuals. More than 10,000 spectra have been visually inspected to\nmeasure the redshift by using combinations of different emission/absorption\nfeatures with uncertainty of $\\sigma_{z}/(1+z)<0.001$. In total, there are 1528\nredshifts (623 absorption and 905 emission line galaxies) in Field A and 1570\nredshifts (569 absorption and 1001 emission line galaxies) in Field B have been\nmeasured. The results show that it is possible to derive redshift from low SNR\ngalaxies with our post-processing and visual inspection. Our analysis also\nindicates that up to 1/4 of the input targets for a typical extra-galactic\nspectroscopic survey might be unreliable. The multi-wavelength data analysis\nshows that the majority of mid-infrared-detected absorption (91.3%) and\nemission line galaxies (93.3%) can be well separated by an empirical criterion\nof $W2-W3=2.4$. Meanwhile, a fainter sequence paralleled to the main population\nof galaxies has been witnessed both in $M_r$/$W2-W3$ and $M_*$/$W2-W3$\ndiagrams, which could be the population of luminous dwarf galaxies but\ncontaminated by the edge-on/highly inclined galaxies ($\\sim30\\%$).", "positive": "Double DCO+ rings reveal CO ice desorption in the outer disk around IM\n Lup: In a protoplanetary disk, a combination of thermal and non-thermal desorption\nprocesses regulate where volatiles are liberated from icy grain mantles into\nthe gas phase. Non-thermal desorption should result in volatile-enriched gas in\ndisk-regions where complete freeze-out is otherwise expected. We present ALMA\nobservations of the disk around the young star IM Lup in 1.4 mm continuum, C18O\n2-1, H13CO+ 3-2 and DCO+ 3-2 emission at ~0\".5 resolution. The images of these\ndust and gas tracers are clearly resolved. The DCO+ line exhibits a striking\npair of concentric rings of emission that peak at radii of ~0\".6 and 2\" (~90\nand 300 AU, respectively). Based on disk chemistry model comparison, the inner\nDCO+ ring is associated with the balance of CO freeze-out and thermal\ndesorption due to a radial decrease in disk temperature. The outer DCO+ ring is\nexplained by non-thermal desorption of CO ice in the low-column-density outer\ndisk, repopulating the disk midplane with cold CO gas. The CO gas then reacts\nwith abundant H2D+ to form the observed DCO+ outer ring. These observations\ndemonstrate that spatially resolved DCO+ emission can be used to trace\notherwise hidden cold gas reservoirs in the outmost disk regions, opening a new\nwindow onto their chemistry and kinematics." }, { "anchor": "Estimating the Oblateness Of Dark Matter Halos Using Neutral Hydrogen\n Velocity Dispersion: We derive the oblateness parameter q of the dark matter halo of a sample of\ngas rich, face-on disk galaxies. We have assumed that the halos are triaxial in\nshape but their axes in the disk plane (a and b) are equal, so that q=c/a\nmeasures the halo flattening. We have used the HI velocity dispersion, derived\nfrom the stacked HI emission lines and the disk surface density to determine\nthe disk potential and the halo shape at the R25 and 1.5R25 radii. We have\napplied our model to 20 nearby galaxies, of which 6 are large disk galaxies\nwith M(stellar)>10^10 solar mass, 8 have moderate stellar masses and 6 are low\nsurface brightness dwarf galaxies. Our most important result is that gas rich\ngalaxies that have M(gas)/M(baryons)>0.5 have oblate halos (q < 0.55), whereas\nstellar dominated galaxies have a range of q values, ranging from 0.21+-0.07 in\nNGC4190 to 1.27+-0.61 in NGC5194. Our results also suggest a positive\ncorrelation between the stellar mass and the halo oblateness q, which indicates\nthat galaxies with massive stellar disks have a higher probability of having\nhalos that are spherical or slightly prolate, whereas low mass galaxies have\noblate halos (q < 0.55).", "positive": "Identifying the progenitors of present-day early-type galaxies in\n observational surveys: correcting `progenitor bias' using the Horizon-AGN\n simulation: As endpoints of the hierarchical mass-assembly process, the stellar\npopulations of local early-type galaxies encode the assembly history of\ngalaxies over cosmic time. We use Horizon-AGN, a cosmological hydrodynamical\nsimulation, to study the merger histories of local early-type galaxies and\ntrack how the morphological mix of their progenitors evolves over time. We\nprovide a framework for alleviating `progenitor bias' -- the bias that occurs\nif one uses only early-type galaxies to study the progenitor population.\nEarly-types attain their final morphology at relatively early epochs -- by\n$z\\sim1$, around 60 per cent of today's early-types have had their last\nsignificant merger. At all redshifts, the majority of mergers have one\nlate-type progenitor, with late-late mergers dominating at $z>1.5$ and\nearly-early mergers becoming significant only at $z<0.5$. Progenitor bias is\nsevere at all but the lowest redshifts -- e.g. at $z\\sim0.6$, less than 50 per\ncent of the stellar mass in today's early-types is actually in progenitors with\nearly-type morphology, while, at $z\\sim2$, studying only early-types misses\nalmost all (80 per cent) of the stellar mass that eventually ends up in local\nearly-type systems. At high redshift, almost all massive late-type galaxies,\nregardless of their local environment or star-formation rate, are progenitors\nof local early-type galaxies, as are lower-mass (M$_\\star$ $<$ 10$^{10.5}$\nM$_{\\odot}$) late-types as long as they reside in high density environments. In\nthis new era of large observational surveys (e.g. LSST, JWST), this study\nprovides a framework for studying how today's early-type galaxies have been\nbuilt up over cosmic time." }, { "anchor": "Forming clusters within clusters: How 30 Doradus recollapsed and gave\n birth again: The 30 Doradus Nebula in the Large Magellanic Cloud (LMC) contains the\nmassive starburst cluster NGC 2070 with a massive and probably younger stellar\nsub clump at its center: R136. It is not clear how such a massive inner cluster\ncould form several million years after the older stars in NGC 2070, given that\nstellar feedback is usually thought to expel gas and inhibit further star\nformation. Using the recently developed 1D feedback scheme WARPFIELD to scan a\nlarge range of cloud and cluster properties, we show that an age offset of\nseveral million years between the stellar populations is in fact to be expected\ngiven the interplay between feedback and gravity in a giant molecular cloud\n(GMC) with a density $\\gtrsim 500$ cm$^{-3}$ due to re-accretion of gas onto\nthe older stellar population. Neither capture of field stars nor gas retention\ninside the cluster have to be invoked in order to explain the observed age\noffset in NGC 2070 as well as the structure of the interstellar medium (ISM)\naround it.", "positive": "Star Formation in Disk Galaxies. III. Does stellar feedback result in\n cloud death?: Stellar feedback, star formation and gravitational interactions are major\ncontrolling forces in the evolution of Giant Molecular Clouds (GMCs). To\nexplore their relative roles, we examine the properties and evolution of GMCs\nforming in an isolated galactic disk simulation that includes both localised\nthermal feedback and photoelectric heating. The results are compared with the\nthree previous simulations in this series which consists of a model with no\nstar formation, star formation but no form of feedback and star formation with\nphotoelectric heating in a set with steadily increasing physical effects. We\nfind that the addition of localised thermal feedback greatly suppresses star\nformation but does not destroy the surrounding GMC, giving cloud properties\nclosely resembling the run in which no stellar physics is included. The\noutflows from the feedback reduce the mass of the cloud but do not destroy it,\nallowing the cloud to survive its stellar children. This suggests that weak\nthermal feedback such as the lower bound expected for supernova may play a\nrelatively minor role in the galactic structure of quiescent Milky Way-type\ngalaxies, compared to gravitational interactions and disk shear." }, { "anchor": "Low-frequency High-resolution Radio Observations of the TeV-emitting\n Blazar SHBLJ001355.9-185406: In the framework of the unification scheme of radio-loud active galactic\nnuclei, BL Lac objects and quasars are the beamed end-on counterparts of\nlow-power (FRI) and high-power (FRII) radio galaxies, respectively. Some BL\nLacs have been found to possess the FRII-type large-scale radio morphology,\nsuggesting that the parent population of BL Lacs is a mixture of low- and\nhigh-power radio galaxies. This seems to apply only to `low frequency-peaked'\nBL Lacs, since all the `high frequency-peaked' BL Lacs studied so far were\nshown to host exclusively the FRI-type radio jets. While analyzing the NVSS\nsurvey maps of the TeV detected BL Lacs, we have however discovered that the\nhigh frequency-peaked object SHBL J001355.9-185406 is associated uniquely with\nthe one-sided, arcmin-scale, and edge-brightened jet/lobe-like feature\nextending to the south-west from the blazar core. In order to investigate in\ndetail the large-scale morphology of SHBL J001355.9-185406, we have performed\nlow-frequency and high-resolution observations of the source at 156, 259 and\n629 MHz using the Giant Metrewave Radio Telescope. Our analysis indicates that\nno diffuse arcmin-scale emission is present around the unresolved blazar core,\nand that the arcmin-scale structure seen on the NVSS map breaks into three\ndistinct features unrelated to the blazar, but instead associated with\nbackground AGN. The upper limits for the extended radio halo around the\nTeV-emitting BL Lac object SHBL J001355.9-185406 read as < 10% - 1% at\n$156-629$ MHz. The fact that the integrated radio spectrum of the unresolved\nblazar core is flat down to 156 MHz indicates that a self-similar character of\nthe jet in the source holds up to relatively large distances from the jet base.", "positive": "Exploring the parent population of beamed NLS1s: from the black hole to\n the jet: The aim of this work is to understand the nature of the parent population of\nbeamed narrow-line Seyfert 1 galaxies (NLS1s), by studying the physical\nproperties of three parent candidates samples: steep-spectrum radio-loud NLS1s,\nradio-quiet NLS1s and disk-hosted radio-galaxies. In particular, we focused on\nthe black hole mass and Eddington ratio distribution and on the interactions\nbetween the jet and the narrow-line region." }, { "anchor": "Stronger Constraints on the Evolution of the $M_{\\rm{BH}}-\u03c3_*$\n Relation up to $z\\sim0.6$: We revisit the possibility of redshift evolution in the\n$M_{\\rm{BH}}-\\sigma_*$ relation with a sample of 22 Seyfert 1 galaxies with\nblack holes (BHs) in the mass range $10^{6.3}-10^{8.3}~M_\\odot$ and redshift\nrange $0.03~0.43. For each evolutionary\ntrack, RT simulations are performed at selected stages, with temperature\nprofiles, SEDs, and images produced. At a given stage the envelope temperature\nis highly dependent on Sigma_cl, but only weakly dependent on M_c. The SED and\nMIR images depend sensitively on the evolving outflow cavity, which gradually\nwides as the protostar grows. The fluxes at <~100 microns increase\ndramatically, and the far-IR peaks move to shorter wavelengths. We find that,\ndespite scatter caused by different M_c, Sigma_cl, beta, and inclinations,\nsources at a given evolutionary stage appear in similar regions on color-color\ndiagrams, especially when using colors at >~ 70 microns, where the scatter due\nto the inclination is minimized, implying that such diagrams can be useful\ndiagnostic tools of evolutionary stages of massive protostars. We discuss how\nintensity profiles along or perpendicular to the outflow axis are affected by\nenvironmental conditions and source evolution." }, { "anchor": "The Web Epoch of Reionization Lyman-$\u03b1$ Survey (WERLS) I. MOSFIRE\n Spectroscopy of $\\mathbf{z \\sim 7-8}$ Lyman-$\u03b1$ Emitters: We present the first results from the Web Epoch of Reionization\nLyman-$\\alpha$ Survey (WERLS), a spectroscopic survey of Lyman-$\\alpha$\nemission using Keck I/MOSFIRE and LRIS. WERLS targets bright ($J<26$) galaxy\ncandidates with photometric redshifts of $5.5\\lesssim z \\lesssim 8$ selected\nfrom pre-JWST imaging embedded in the Epoch of Reionization (EoR) within three\nJWST deep fields: CEERS, PRIMER, and COSMOS-Web. Here, we report 11 $z\\sim7-8$\nLyman-$\\alpha$ emitters (LAEs; 3 secure and 8 tentative candidates) detected in\nthe first five nights of WERLS MOSFIRE data. We estimate our observed LAE yield\nis $\\sim13$%, broadly consistent with expectations assuming some loss from\nredshift uncertainty, contamination from sky OH lines, and that the Universe is\napproximately half-ionized at this epoch, whereby observable Lyman-$\\alpha$\nemission is unlikely for galaxies embedded in a neutral intergalactic medium.\nOur targets are selected to be UV-bright, and span a range of absolute UV\nmagnitudes with $-23.1 < M_{\\text{UV}} < -19.8$. With two LAEs detected at\n$z=7.68$, we also consider the possibility of an ionized bubble at this\nredshift. Future synergistic Keck+JWST efforts will provide a powerful tool for\npinpointing beacons of reionization and mapping the large scale distribution of\nmass relative to the ionization state of the Universe.", "positive": "On the BL Lacertae objects/radio quasars and the FRI/II dichotomy: In the frame of unification schemes for radio-loud active galactic nuclei\n(AGNs), FR I radio galaxies are believed to be BL Lacertae (BL Lac) objects\nwith the relativistic jet misaligned to our line of sight, and FR II radio\ngalaxies correspond to misaligned radio quasars. The Ledlow-Owen dividing line\nfor FR I/FR II dichotomy in the optical absolute magnitude of host galaxy-radio\nluminosity (M_R-L_Rad) plane can be translated to the line in the black hole\nmass-jet power (M_bh-Q_jet) plane by using two empirical relations: Q_jet-L_Rad\nand M_bh}-M_R. We use a sample of radio quasars and BL Lac objects with\nmeasured black hole masses to explore the relation of the jet power with black\nhole mass, in which the jet power is estimated from the extended radio\nemission. It is found that the BL Lac objects are clearly separated from radio\nquasars by the Ledlow & Owen FR I/II dividing line in the M_bh-Q_jet plane.\nThis strongly supports the unification schemes for FR I/BL Lac object and FR\nII/radio quasar. We find that the Eddington ratios L_bol/L_Edd of BL Lac\nobjects are systematically lower than those of radio quasars in the sample with\na rough division at L_bol/L_Edd 0.01, and the distribution of Eddington ratios\nof BL Lac objects/quasars exhibits a bimodal nature, which imply that the\naccretion mode of BL Lac objects may be different from that of radio quasars." }, { "anchor": "Direct Imaging of a Compact Molecular Outflow from a Very Low-luminosity\n Object; L1521F-IRS: We report interferometric observations of the VeLLO L1521F-IRS, in 12CO (2-1)\nline emission and the 1.3 mm continuum emission, using the Submillimeter Array\n(SMA). With the 12CO high-resolution observations, we have spatially resolved a\ncompact but poorly collimated molecular outflow associated with L1521F-IRS for\nthe first time. The blueshifted and redshifted lobes are aligned along the east\nand west side of L1521F-IRS with a lobe size of ~1000 AU. The estimated outflow\nmass, maximum outflow velocity, and outflow force are (9.0-80)x10^{-4} M_{sol},\n7.2 km s^{-1}, and (7.4-66)x10^{-7} M_{sol} km s^{-1} yr^{-1}, respectively.\nThe estimated outflow parameters such as size, mass, and momentum rate are\nsimilar to values derived for other VeLLOs, and are located at the lower end of\nvalues compared to previously studied outflows associated with low- to\nhigh-mass star forming regions. Low-velocity less collimated (1.5 km\ns^{-1}/1200 AU) and higher-velocity compact (4.0 km s^{-1}/920 AU) outflow\ncomponents are suggested by the data. These velocity structures are not\nconsistent with those expected in the jet driven or wind driven outflow models,\nperhaps suggesting a remnant outflow from the FHSC as well as an undeveloped\noutflow from the protostar. Detection of an infrared source and compact\nmillimeter continuum emission suggest the presence of the protostar, while its\nlow bolometric luminosity (0.034-0.07 L$_{\\odot}$), and small outflow, suggests\nthat L1521F is in the earliest protostellar stage ($<10^{4}$ yr) and contains a\nsubstellar mass object. The bolometric (or internal) luminosity of L1521F-IRS\nsuggests that the current mass accretion rate is an order-of-magnitude lower\nthan expected in the standard mass accretion model (~10^{-6} M_{sol} yr^{-1}),\nwhich may imply that L1521F-IRS is currently in a low activity phase.", "positive": "The Shape of Dark Matter Haloes, V. Analysis of observations of edge-on\n galaxies: In the previous papers in this series, we have measured the stellar and \\hi\ncontent in a sample of edge-on galaxies. In the present paper, we perform a\nsimultaneous rotation curve and vertical force field gradient decomposition for\nfive of these edge-on galaxies. The rotation curve decomposition provides a\nmeasure of the radial dark matter potential, while the vertical force field\ngradient provide a measure of the vertical dark matter potential. We fit dark\nmatter halo models to these potentials. Using our \\hi self-absorption results,\nwe find that a typical dark matter halo has a less dense core\n($0.094\\pm0.230$\\,M$_\\odot$/pc$^3$) compared to an optically thin \\hi model\n($0.150\\pm0.124$\\,M$_\\odot$/pc$^3$). The HI self-absorption dark matter halo\nhas a longer scale length $R_c$ of $1.42\\pm 3.48$\\,kpc, versus $1.10\\pm\n1.81$\\,kpc for the optically thin HI model. The median halo shape is spherical,\nat $q=1.0\\pm0.6$ (self-absorbing \\hi), while it is prolate at $q=1.5\\pm0.6$ for\nthe optically thin. Our best results were obtained for ESO\\,274-G001 and\nUGC\\,7321, for which we were able to measure the velocity dispersion in Paper\nIII. These two galaxies have drastically different halo shapes, with one oblate\nand one strongly prolate. Overall, we find that the many assumptions required\nmake this type of analysis susceptible to errors." }, { "anchor": "Modal analysis of gravitational instabilities in nearly Keplerian,\n counter-rotating collisionless discs: We present a modal analysis of instabilities of counter-rotating,\nself-gravitating collisionless stellar discs, using the recently introduced\nmodified WKB formulation of spiral density waves for collisionless systems\n(Gulati \\& Saini). The discs are assumed to be axisymmetric and in coplanar\norbits around a massive object at the common center of the discs. The mass in\nboth discs is assumed to be much smaller than the mass of the central object.\nFor each disc, the disc particles are assumed to be in near circular orbits.\nThe two discs are coupled to each other gravitationally. The perturbed dynamics\nof the discs evolves on the order of the precession time scale of the discs,\nwhich is much longer than the Keplerian time scale. We present results for the\nazimuthal wave number $m=1$ and $m=2$, for the full range of disc mass ratio\nbetween the prograde and retrograde discs. The eigenspectra are in general\ncomplex, therefore all eigenmodes are unstable. Eigenfunctions are radially\nmore compact for $m = 1$ as compared to $m = 2$. Pattern speed of eigenmodes is\nalways prograde with respect to the more massive disc. The growth rate of\nunstable modes increases with increasing mass fraction in the retrograde disc,\nand decreases with $m$; therefore $m=1$ instability is likely to play the\ndominant role in the dynamics of such systems.", "positive": "An Ordered Envelope-disk Transition in the Massive Protostellar Source\n G339.88-1.26: We report molecular line observations of the massive protostellar source\nG339.88-1.26 with the Atacama Large Millimeter/Submillimeter Array. The\nobservations reveal a highly collimated SiO jet extending from the 1.3 mm\ncontinuum source, which connects to a slightly wider but still highly\ncollimated CO outflow. Rotational features perpendicular to the outflow axis\nare detected in various molecular emissions, including SiO, SO2, H2S, CH3OH,\nand H2CO emissions. Based on their spatial distributions and kinematics, we\nfind that they trace different parts of the envelope-disk system. The SiO\nemission traces the disk and inner envelope in addition to the jet. The CH3OH\nand H2CO emissions mostly trace the infalling-rotating envelope, and are\nenhanced around the transition region between envelope and disk, i.e., the\ncentrifugal barrier. The SO2 and H2S emissions are enhanced around the\ncentrifugal barrier, and also trace the outer part of the disk. Envelope\nkinematics are consistent with rotating-infalling motion, while those of the\ndisk are consistent with Keplerian rotation. The radius and velocity of the\ncentrifugal barrier are estimated to be about 530 au and 6 km/s, leading to a\ncentral mass of about 11 solar masses, consistent with estimates based on\nspectral energy distribution fitting. These results indicate that an ordered\ntransition from an infalling-rotating envelope to a Keplerian disk through a\ncentrifugal barrier, accompanied by changes of types of molecular line\nemissions, is a valid description of this massive protostellar source. This\nimplies that at least some massive stars form in a similar way as low-mass\nstars via Core Accretion." }, { "anchor": "New constraints on quasar broad absorption and emission line regions\n from gravitational microlensing: Gravitational microlensing is a powerful tool allowing one to probe the\nstructure of quasars on sub-parsec scale. We report recent results, focusing on\nthe broad absorption and emission line regions. In particular microlensing\nreveals the intrinsic absorption hidden in the P Cygni-type line profiles\nobserved in the broad absorption line quasar H1413+117, as well as the\nexistence of an extended continuum source. In addition, polarization\nmicrolensing provides constraints on the scattering region. In the quasar\nQ2237+030, microlensing differently distorts the H$\\alpha$ and CIV broad\nemission line profiles, indicating that the low- and high-ionization broad\nemission lines must originate from regions with distinct kinematical\nproperties. We also present simulations of the effect of microlensing on line\nprofiles considering simple but representative models of the broad emission\nline region. Comparison of observations to simulations allows us to conclude\nthat the H$\\alpha$ emitting region in Q2237+030 is best represented by a\nKeplerian disk.", "positive": "Three dimensional projection effects on chemistry in a Planck galactic\n cold clump: Offsets of molecular line emission peaks from continuum peaks are very common\nbut frequently difficult to explain with a single spherical cloud chemical\nmodel. We propose that the spatial projection effects of an irregular three\ndimensional (3D) cloud structure can be a solution. This work shows that the\nidea can be successfully applied to the Planck cold clump G224.4-0.6 by\napproximating it with four individual spherically symmetric cloud cores whose\nchemical patterns overlap with each other to produce observable line maps. With\nthe empirical physical structures inferred from the observation data of this\nclump and a gas-grain chemical model, the four cores can satisfactorily\nreproduce its 850 $\\mu$m continuum map and the diverse peak offsets of CCS,\nHC$_3$N and N$_2$H$^+$ simultaneously at chemical ages of about $8\\times\n10^5\\sim 3\\times 10^6$ yrs. The 3D projection effects on chemistry has the\npotential to explain such asymmetrical distributions of chemicals in many other\nmolecular clouds." }, { "anchor": "Ultraviolet Measurements of Interstellar C2: We analyzed archival spectra acquired with the Hubble Space Telescope for a\nstudy of interstellar C2. Absorption from the electronic transitions, D\n^1Sigma^+_u -- X ^1Sigma^+_g (0,0) as well as F ^1Pi_u -- X ^1Sigma^+_g (0,0)\nand (1,0), was the focus of the study. Our profile syntheses revealed that the\nlines of the F-X bands were broadened as a result of a perturbation involving\nthe upper levels. Further evidence for the perturbation came from anomalies in\nline strength and position for the F-X (0,0) band. The perturbation likely\narises from a combination of triplet-singlet interactions involving spin-orbit\nmixing between ^3Pi_u states and F ^1Pi_u and an avoided crossing between the\n^3Pi_u states. Tunneling through a potential barrier caused by the 3 and 4\n^1Pi_u states and spin-orbit mixing with other close-lying triplet states of\nungerade symmetry are less likely. Except for the broadening, lines in the F-X\n(1,0) band appear free from anomalies and can be used to study interstellar C2;\nnew results for 10 sight lines are presented.", "positive": "Absorption-selected galaxies trace the low-mass, late-type, star-forming\n population at $z\\sim2-3$: We report on the stellar content, half-light radii and star formation rates\nof a sample of 10 known high-redshift ($z\\gtrsim 2$) galaxies selected on\nstrong neutral hydrogen (HI) absorption (log(N(HI)/cm$^{-2})>19$) toward\nbackground quasars. We use observations from the {\\it Hubble Space Telescope}\n(HST) Wide Field Camera 3 in three broad-band filters to study the spectral\nenergy distribution(SED) of the galaxies. Using careful quasar point spread\nfunction subtraction, we study their galactic environments, and perform the\nfirst systematic morphological characterisation of such absorption-selected\ngalaxies at high redshifts. Our analysis reveals complex, irregular hosts with\nmultiple star-forming clumps. At a spatial sampling of 0.067 arcsec per pixel\n(corresponding to 0.55 kpc at the median redshift of our sample), 40% of our\nsample requires multiple S\\'ersic components for an accurate modelling of the\nobserved light distributions. Placed on the mass-size relation and the `main\nsequence' of star-forming galaxies, we find that absorption-selected galaxies\nat high redshift extend known relations determined from deep\nluminosity-selected surveys to an order of magnitude lower stellar mass, with\nobjects primarily composed of star-forming, late-type galaxies. We measure\nhalf-light radii in the range $r_{1/2} \\sim$ 0.4 to 2.6 kpc based on the\nreddest band (F160W) to trace the oldest stellar populations, and stellar\nmasses in the range $\\log (\\mathrm{M}_{\\star}/\\mathrm{M}_{\\odot}) \\sim$ 8 to 10\nderived from fits to the broad-band SED. Spectroscopic and SED-based star\nformation rates are broadly consistent, and lie in the range log(SFR/M$_{\\odot}\n$yr$^{-1}$) $\\sim$0.0 to 1.7." }, { "anchor": "Benchmark Studies on the Isomerization Enthalpies for Interstellar\n Molecular Species: With the well-established correlation between the relative stabilities of\nisomers and their interstellar abundances coupled with the prevalence of\nisomeric species among the interstellar molecular species, isomerization\nremains a plausible formation route for isomers in the interstellar medium. The\npresent work reports an extensive investigation of the isomerization energies\nof 246 molecular species from 65 isomeric groups using the Gaussian-4 theory\ncomposite method with atoms ranging from 3 to 12. From the results, the high\nabundances of the most stable isomers coupled with the energy sources in\ninterstellar medium drive the isomerization process even for barriers as high\nas 67.4 kcal/mol. Specifically, the cyanides and their corresponding\nisocyanides pairs appear to be effectively synthesized via this process. The\nfollowing potential interstellar molecules; CNC, NCCN, c-C5H, methylene ketene,\nmethyl Ketene, CH3SCH3, C5O, 1,1-ethanediol, propanoic acid, propan-2-ol, and\npropanol are identified and discussed. The study further reaffirms the\nimportance of thermodynamics in interstellar formation processes on a larger\nscale and accounts for the known isomeric species. In all the isomeric groups,\nisomerization appears to be an effective route for the formation of the less\nstable isomers (which are probably less abundant) from the most stable ones\nthat are perhaps more abundant.", "positive": "Diffuse Gas in Galaxies Sheds New Light on the Origin of Type Ia\n Supernovae: We measure the strength of HeII$\\lambda$4686 nebular emission in passively\nevolving (\"retired\") galaxies, aiming to constrain their populations of hot\naccreting white dwarfs (WDs) in the context of the single degenerate (SD)\nscenario of Type Ia supernovae (SNe Ia). In the SD scenario, as a WD burns\nhydrogen-rich material accreted from a companion star, it becomes a powerful\nsource of ionizing UV emission. If significant populations of such sources\nexist in galaxies, strong emission in the recombination lines of HeII should be\nexpected from the interstellar medium. To explore this conjecture, we select\nfrom the Sloan Digital Sky Survey ~11 500 emission line galaxies with stellar\nages >1 Gyr showing no signs of AGN activity and co-add their spectra in bins\nof stellar population age. For the first time, we detect HeII$\\lambda$4686\nnebular emission in retired galaxies and find it to be significantly weaker\nthan that expected in the SD scenario, especially in the youngest age bin (1-4\nGyr) where the SN Ia rate is the highest. Instead, the strength of the observed\nHeII$\\lambda$4686 nebular emission is consistent with post-asymptotic giant\nbranch stars being the sole ionizing source in all age bins. These results\nlimit populations of accreting WDs with photospheric temperatures ($T_{\\rm\neff}$) in the range ~(1.5-6)$\\cdot 10^5$ K to the level at which they can\naccount for no more than ~5-10% of the observed SN Ia rate. Conversely, should\nall WD progenitors of SN Ia go through the phase of steady nuclear burning with\n$T_{\\rm eff}$~(1.5-6)$\\cdot 10^5$ K, they do not increase their mass by more\nthan ~0.03 $M_\\odot$ in this regime." }, { "anchor": "Trigonometric Parallaxes of Massive Star-Forming Regions. IX. The Outer\n Arm in the First Quadrant: We report a trigonometric parallax measurement with the Very Long Baseline\nArray for the water maser in the distant high-mass star-forming region\nG75.30+1.32. This source has a heliocentric distance of 9.25+-0.45 kpc, which\nplaces it in the Outer arm in the first Galactic quadrant. It lies 200 pc above\nthe Galactic plane and is associated with a substantial HI enhancement at the\nborder of a large molecular cloud. At a Galactocentric radius of 10.7 kpc,\nG75.30+1.32 is in a region of the Galaxy where the disk is significantly warped\ntoward the North Galactic Pole. While the star-forming region has an\ninstantaneous Galactic orbit that is nearly circular, it displays a significant\nmotion of 18 km/s toward the Galactic plane. The present results, when combined\nwith two previous maser studies in the Outer arm, yield a pitch angle of about\n12 degrees for a large section of the arm extending from the first quadrant to\nthe third.", "positive": "Extended narrow-line region in Seyfert galaxies: We present our recent results about the extended narrow-line region (ENLR) of\ntwo nearby Seyfert 2 galaxies (IC 5063 and NGC 7212) obtained by modelling the\nobserved line profiles and spectra with composite models\n(photoionization+shocks) in the different regions surrounding the AGN. Then, we\ncompare the Seyfert 2 ENLRs with the very extended one recently discovered in\nthe narrow-line Seyfert 1 (NLS1) galaxy Mrk 783. We have found several\nevidences of interaction between the ISM of the galaxies and their radio jets,\nsuch as a) the contribution of shocks in ionizing the high velocity gas, b) the\ncomplex kinematics showed by the profile of the emission lines, c) the high\nfragmentation of matter, etc. The results suggest that the ENLR of IC 5063 have\na hollow bi-conical shape, with one edge aligned to the galaxy disk, which may\ncause some kind of dependence on velocity of the ionization parameter.\nRegarding the Mrk 783 properties, it is found that the extension of the optical\nemission is almost twice the size of the radio one and it seems due to the AGN\nactivity, although there is contamination by star formation around 12 arcsec\nfrom the nucleus. Diagnostic diagrams excluded the contribution of star\nformation in IC 5063 and NGC 7212, while the shock contribution was used to\nexplain the spectra emitted by their high velocity gas." }, { "anchor": "Breaking Orion's Veil bubble with fossil outflows: The role of feedback in the self-regulation of star formation is a\nfundamental question in astrophysics. The Orion Nebula is the nearest site of\nongoing and recent massive star formation. It is a unique laboratory for the\nstudy of stellar feedback. Recent SOFIA [CII] 158 $\\mu$m observations revealed\nan expanding bubble, the Veil shell, being powered by stellar winds and\nionization feedback. We have identified a protrusion-like substructure in the\nNorthwest portion of the Orion Veil Shell that may indicate additional feedback\nmechanisms that are highly directional. Our goal is to investigate the origin\nof the protrusion by quantifying its possible driving mechanisms. We use the\n[CII] 158 $\\mu$m map of the Orion Nebula obtained with the upGREAT instrument\nonboard SOFIA. The spectral and spatial resolution of the observations are 0.3\nkm/s and 16 arcsec, respectively.\n We consider three possible origins for this protrusion: Fossil outflow\ncavities created by jets/outflows during the protostellar accretion phase,\npre-existing clumpiness in the OMC-1 core, and the stellar wind during the main\nsequence phase. Based on the energetics and the morphology, we conclude that\nthe northwestern part of the pre-existing cloud was locally perturbed by\noutflows ejected from massive protostars in the Trapezium cluster. This\nsuggests that the protrusion of the Veil is the result of mechanical rather\nthan radiative feedback. Furthermore, we argue that the location of the\nprotrusion is a suitable place to break the Orion Veil owing to the\nphoto-ablation from the walls of the protrusion. We conclude that the outflows\nof massive protostars can influence the morphology of the future \\hii\\,region\nand even cause breakages in the ionization front. Specifically, the interaction\nof stellar winds of main-sequence stars with the molecular core pre-processed\nby the protostellar jet is important.", "positive": "Modeling the Resolved Disk Around the Class 0 Protostar L1527: We present high-resolution sub/millimeter interferometric imaging of the\nClass 0 protostar L1527 IRS (IRAS 04368+2557) at 870 micron and 3.4 mm from the\nSubmillimeter Array (SMA) and Combined Array for Research in Millimeter\nAstronomy (CARMA). We detect the signature of an edge-on disk surrounding the\nprotostar with an observed diameter of 180 AU in the sub/millimeter images. The\nmass of the disk is estimated to be 0.007 M_sun, assuming optically thin,\nisothermal dust emission. The millimeter spectral index is observed to be quite\nshallow at all the spatial scales probed; alpha ~ 2, implying a dust opacity\nspectral index beta ~ 0. We model the emission from the disk and surrounding\nenvelope using Monte Carlo radiative transfer codes, simultaneously fitting the\nsub/millimeter visibility amplitudes, sub/millimeter images, resolved L\\arcmin\\\nimage, spectral energy distribution, and mid-infrared spectrum. The best\nfitting model has a disk radius of R = 125 AU, is highly flared (H ~ R^1.3),\nhas a radial density profile rho ~ R^-2.5, and has a mass of 0.0075 M_sun. The\nscale height at 100 AU is 48 AU, about a factor of two greater than vertical\nhydrostatic equilibrium. The resolved millimeter observations indicate that\ndisks may grow rapidly throughout the Class 0 phase. The mass and radius of the\nyoung disk around L1527 is comparable to disks around pre-main sequence stars;\nhowever, the disk is considerably more vertically extended, possibly due to a\ncombination of lower protostellar mass, infall onto the disk upper layers, and\nlittle settling of ~1 micron-sized dust grains." }, { "anchor": "Testing metallicity indicators at z~1.4 with the gravitationally lensed\n galaxy CASSOWARY 20: We present X-shooter observations of CASSOWARY 20 (CSWA 20), a star-forming\n(SFR ~6 Msol/yr) galaxy at z=1.433, magnified by a factor of 11.5 by the\ngravitational lensing produced by a massive foreground galaxy at z=0.741. We\nanalysed the integrated physical properties of the HII regions of CSWA 20 using\ntemperature- and density-sensitive emission lines. We find the abundance of\noxygen to be ~1/7 of solar, while carbon is ~50 times less abundant than in the\nSun. The unusually low C/O ratio may be an indication of a particularly rapid\ntimescale of chemical enrichment. The wide wavelength coverage of X-shooter\ngives us access to five different methods for determining the metallicity of\nCSWA 20, three based on emission lines from HII regions and two on absorption\nfeatures formed in the atmospheres of massive stars. All five estimates are in\nagreement, within the factor of ~2 uncertainty of each method. The interstellar\nmedium of CSWA 20 only partially covers the star-forming region as viewed from\nour direction; in particular, absorption lines from neutrals and first ions are\nexceptionally weak. We find evidence for large-scale outflows of the\ninterstellar medium (ISM) with speeds of up 750 km/s, similar to the values\nmeasured in other high-z galaxies sustaining much higher rates of star\nformation.", "positive": "Big Three Dragons: Molecular Gas in a Bright Lyman-Break Galaxy at\n $z=7.15$: We report ALMA Band 3 observations of CO(6-5), CO(7-6), and [CI](2-1) in\nB14-65666 (``Big Three Dragons''), one of the brightest Lyman-Break Galaxies at\n$z>7$ in the rest-frame ultraviolet continuum, far-infrared continuum, and\nemission lines of [OIII] 88 $\\mu$m and [CII] 158 $\\mu$m. CO(6-5), CO(7-6), and\n[CI](2-1), whose $3\\sigma$ upper limits on the luminosities are approximately\n40 times fainter than the [CII] luminosity, are all not detected. The $L_{\\rm\n[CII]}$/$L_{\\rm CO(6-5)}$ and $L_{\\rm [CII]}$/$L_{\\rm CO(7-6)}$ ratios are\nhigher than the typical ratios obtained in dusty star-forming galaxies or\nquasar host galaxies at similar redshifts, and they may suggest a lower gas\ndensity in the photodissociated region in B14-65666. By using the (1) [CII]\nluminosity, (2) dust mass-to-gas mass ratio, and (3) a dynamical mass estimate,\nwe find that the molecular gas mass ($M_{\\rm{mol}}$) is\n$(0.05-11)\\times10^{10}$ $M_{\\rm \\odot}$. This value is consistent with the\nupper limit inferred from the nondetection of mid-$J$ CO and [CI](2-1). Despite\nthe large uncertauinty in $M_{\\rm mol}$, we estimate a molecular gas-to-stellar\nmass ratio ($\\mu_{\\rm{gas}}$) of $0.65-140$ and a gas depletion time\n($\\tau_{\\rm dep}$) of $2.5-550$ Myr; these values are broadly consistent with\nthose of other high-redshift galaxies. B14-65666 could be an ancestor of a\npassive galaxy at $z\\gtrsim4$ if no gas is fueled from outside the galaxy." }, { "anchor": "Neutral versus ionized gas kinematics at z~2.6: The AGN-host starburst\n galaxy PKS 0529-549: We present a multiwavelength study of the AGN-host starburst galaxy PKS\n0529-549 at z~2.6. We use (1) new ALMA observations of the dust continuum and\nof the [CI] 370 um line, tracing molecular gas, (2) SINFONI spectroscopy of the\n[OIII] 5007 Ang line, tracing ionized gas, and (3) ATCA radio continuum images,\ntracing synchrotron emission. Both [CI] and [OIII] show regular velocity\ngradients, but their systemic velocities and position angles differ by ~300\nkm/s and ~30 degrees, respectively. The [CI] is consistent with a rotating\ndisc, aligned with the dust and stellar continuum, while the [OIII] likely\ntraces an outflow, aligned with two AGN-driven radio lobes. We model the [CI]\ncube using 3D disc models, which give best-fit rotation velocities V~310 km/s\nand velocity dispersions sigma<30 km/s. Hence, the [CI] disc has V/sigma>10 and\nis not particularly turbulent, similar to local galaxy discs. The dynamical\nmass (~10^11 Msun) is comparable to the baryonic mass within the errors. This\nsuggests that baryons dominate the inner galaxy dynamics, similar to massive\ngalaxies at z=0. Remarkably, PKS 0529-549 lies on the local baryonic\nTully-Fisher relation, indicating that at least some massive galaxies are\nalready in place and kinematically relaxed at z~2.6. This work highlights the\npotential of the [CI] line to trace galaxy dynamics at high z, as well as the\nimportance of multiwavelength data to interpret gas kinematics.", "positive": "Quasars Have Fewer Close Companions than Normal Galaxies: We investigate the distribution of companion galaxies around quasars using\n{\\em Hubble Space Telescope} ({\\em HST}) Advanced Camera for Surveys Wide Field\nCamera (ACS/WFC) archival images. Our master sample contains 532 quasars which\nhave been observed by {\\em HST} ACS/WFC, spanning a wide range of luminosity\n$(-3190\\%)$ even for the faintest companions\nof interest. The number of physical companions is estimated by subtracting a\nbackground density from the number density of projected companions. We divide\nall the companions into three groups (faint, intermediate and bright) according\nto their fluxes. A control sample of galaxies is constructed to have similar\nredshift distribution and stellar mass range as the quasar sample using the\ndata from {\\em HST} deep fields. We find that quasars and control sample\ngalaxies have similar numbers of faint and bright companions, while quasars\nshow a $3.7\\sigma$ deficit of intermediate companions compared to galaxies. The\nnumbers of companions in all three groups do not show strong evolution with\nredshift, and the number of intermediate companions around quasars decreases\nwith quasar luminosity. Assuming that merger-triggered quasars have entered the\nfinal coalescence stage during which individual companions are no longer\ndetectable at large separations, our result is consistent with a picture in\nwhich a significant fraction of quasars is triggered by mergers." }, { "anchor": "First M87 Event Horizon Telescope Results. I. The Shadow of the\n Supermassive Black Hole: When surrounded by a transparent emission region, black holes are expected to\nreveal a dark shadow caused by gravitational light bending and photon capture\nat the event horizon. To image and study this phenomenon, we have assembled the\nEvent Horizon Telescope, a global very long baseline interferometry array\nobserving at a wavelength of 1.3 mm. This allows us to reconstruct\nevent-horizon-scale images of the supermassive black hole candidate in the\ncenter of the giant elliptical galaxy M87. We have resolved the central compact\nradio source as an asymmetric bright emission ring with a diameter of 42+/-3\nmicro-as, which is circular and encompasses a central depression in brightness\nwith a flux ratio ~10:1. The emission ring is recovered using different\ncalibration and imaging schemes, with its diameter and width remaining stable\nover four different observations carried out in different days. Overall, the\nobserved image is consistent with expectations for the shadow of a Kerr black\nhole as predicted by general relativity. The asymmetry in brightness in the\nring can be explained in terms of relativistic beaming of the emission from a\nplasma rotating close to the speed of light around a black hole. We compare our\nimages to an extensive library of ray-traced general-relativistic\nmagnetohydrodynamic simulations of black holes and derive a central mass of M =\n(6.5+/-0.7) x 10^9 Msun. Our radio-wave observations thus provide powerful\nevidence for the presence of supermassive black holes in centers of galaxies\nand as the central engines of active galactic nuclei. They also present a new\ntool to explore gravity in its most extreme limit and on a mass scale that was\nso far not accessible.", "positive": "Machine Learning and galaxy morphology: for what purpose?: Classification of galaxies is traditionally associated with their\nmorphologies through visual inspection of images. The amount of data to come\nrenders this task inhuman and Machine Learning (mainly Deep Learning) has been\ncalled to the rescue for more than a decade. However, the results look mitigate\nand there seems to be a shift away from the paradigm of the traditional\nmorphological classification of galaxies. In this paper, I want to show that\nthe algorithms indeed are very sensitive to the features present in images,\nfeatures that do not necessarily correspond to the Hubble or de Vaucouleurs\nvision of a galaxy. However, this does not preclude to get the correct insights\ninto the physics of galaxies. I have applied a state-of-the-art ''traditional''\nMachine Learning clustering tool, called Fisher-EM, a latent discriminant\nsubspace Gaussian Mixture Model algorithm, to 4458 galaxies carefully\nclassified into 18 types by the EFIGI project. The optimum number of clusters\ngiven by the Integrated Complete Likelihood criterion is 47. The correspondence\nwith the EFIGI classification is correct, but it appears that the Fisher-EM\nalgorithm gives a great importance to the distribution of light which\ntranslates to characteristics such as the bulge to disk ratio, the inclination\nor the presence of foreground stars. The discrimination of some physical\nparameters (bulge-to-total luminosity ratio, $(B -- B)T$ , intrinsic diameter,\npresence of flocculence or dust, arm strength) is very comparable in the two\nclassifications." }, { "anchor": "The Spatial Relation between Young Star Clusters and Molecular Clouds in\n M 51 with LEGUS: We present a study correlating the spatial locations of young star clusters\nwith those of molecular clouds in NGC~5194, in order to investigate the\ntimescale over which clusters separate from their birth clouds. The star\ncluster catalogues are from the Legacy ExtraGalactic UV Survey (LEGUS) and the\nmolecular clouds from the Plateau de Bure Interefrometer Arcsecond Whirpool\nSurvey (PAWS). We find that younger star clusters are spatially closer to\nmolecular clouds than older star clusters. The median ages for clusters\nassociated with clouds is 4~Myr whereas it is 50~Myr for clusters that are\nsufficiently separated from a molecular cloud to be considered unassociated.\nAfter $\\sim$6~Myr, the majority of the star clusters lose association with\ntheir molecular gas. Younger star clusters are also preferentially located in\nstellar spiral arms where they are hierarchically distributed in kpc-size\nregions for 50-100~Myr before dispersing. The youngest star clusters are more\nstrongly clustered, yielding a two-point correlation function with\n$\\alpha=-0.28\\pm0.04$, than the GMCs ($\\alpha=-0.09\\pm0.03$) within the same\nPAWS field. However, the clustering strength of the most massive GMCs,\nsupposedly the progenitors of the young clusters for a star formation\nefficiency of a few percent, is comparable ($\\alpha=-0.35\\pm0.05$) to that of\nthe clusters. We find a galactocentric-dependence for the coherence of star\nformation, in which clusters located in the inner region of the galaxy reside\nin smaller star-forming complexes and display more homogeneous distributions\nthan clusters further from the centre. This result suggests a correlation\nbetween the survival of a cluster complex and its environment.", "positive": "Linking UV spectral properties of MUSE Ly-alpha emitters at z>3 to Lyman\n continuum escape: The physical conditions giving rise to high escape fractions of ionizing\nradiation (LyC $f_{\\rm{esc}}$) in star-forming galaxies - most likely\nprotagonists of cosmic reionization - are not yet fully understood. Using the\nVLT/MUSE observations of ~1400 Ly$\\alpha$ emitters at 2.9 < z < 6.7, we compare\nstacked rest-frame UV spectra of candidates for LyC leakers and non-leakers\nselected based on their Ly$\\alpha$ profiles. We find that the stacks of\npotential LyC leakers, i.e. galaxies with narrow, symmetric Ly$\\alpha$ profiles\nwith small peak separation, generally show (i) strong nebular OIII]1666,\n[SiIII]1883, and [CIII]1907+CIII]1909 emission, indicating a high-ionization\nstate of the interstellar medium (ISM); (ii) high equivalent widths of HeII1640\n(~1-3 A), suggesting the presence of hard ionizing radiation fields; (iii)\nSiII*1533 emission, revealing substantial amounts of neutral hydrogen off the\nline of sight; (iv) high CIV1548,1550 to [CIII]1907+CIII]1909 ratios (CIV/CIII]\n> 0.75), signalling the presence of low column density channels in the ISM. In\ncontrast, the stacks with broad, asymmetric Ly$\\alpha$ profiles with large peak\nseparation show weak nebular emission lines, low HeII1640 equivalent widths (<1\nA), and low CIV/CIII] (<0.25), implying low-ionization states and high-neutral\nhydrogen column densities. Our results suggest that CIV/CIII] might be\nsensitive to the physical conditions that govern LyC photon escape, providing a\npromising tool for identification of ionizing sources among star-forming\ngalaxies in the epoch of reionization." }, { "anchor": "LoCuSS: exploring the connection between local environment, star\n formation and dust mass in Abell 1758: We explore the connection between dust and star formation, in the context of\nenvironmental effects on galaxy evolution. In particular, we exploit the\nsusceptibility of dust to external processes to assess the influence of dense\nenvironment on star-forming galaxies. We have selected cluster Abell 1758 from\nthe Local Cluster Substructure Survey (LoCuSS). Its complex dynamical state is\nan ideal test-bench to track dust removal and destruction in galaxies due to\nmerger and accretion shocks. We present a systematic panchromatic study (from\n0.15 $\\rm \\mu$m with GALEX to 500 $\\rm \\mu$m with Herschel) of\nspectroscopically confirmed star-forming cluster galaxies at intermediate\nredshift. We observe that the main subclusters (A1758N and A1758S) belong to\ntwo separate large-scale structures, with no overlapping galaxy members.\nStar-forming cluster members are distributed preferentially outside cluster\ncentral regions, and are not grouped in substructures. Rather, these galaxies\nare being funneled towards the main subclusters along separate accretion\nfilaments. Additionally, we present the first study of dust-to-stellar (DTS)\nmass ratio used as indicator for local environmental influence on galaxy\nevolution. Star-forming cluster members show lower mean values (32% at 2.4$\\rm\n\\sigma$) of DTS mass ratio and lower levels of infrared emission from birth\nclouds with respect to coeval star-forming field galaxies. This picture is\nconsistent with the majority of star-forming cluster members infalling in\nisolation. Upon accretion, star-formation is observed to decrease and warm dust\nis destroyed due to heating from the intracluster medium radiation,\nram-pressure stripping and merger shocks.", "positive": "The dependence of subhalo abundance matching on galaxy photometry and\n selection criteria: Subhalo abundance matching (SHAM) is a popular technique for assigning galaxy\nmass or luminosity to haloes produced in N-body simulations. The method works\nby matching the cumulative number functions of the galaxy and halo properties,\nand is therefore sensitive both to the precise definitions of those properties\nand to the selection criteria used to define the samples. Further dependence\nfollows when SHAM parameters are calibrated with galaxy clustering, which is\nknown to depend strongly on the manner in which galaxies are selected. In this\npaper we introduce a new parametrisation for SHAM and derive the best-fit SHAM\nparameters as a function of various properties of the selection of the galaxy\nsample and of the photometric definition, including S\\'ersic vs Petrosian\nmagnitudes, stellar masses vs r-band magnitudes and optical (SDSS) vs HI\n(ALFALFA) selection. In each case we calculate the models' goodness-of-fit to\nmeasurements of the projected two-point galaxy correlation function. In the\noptically-selected samples we find strong evidence that the scatter in the\ngalaxy-halo connection increases towards the faint end, and that AM performs\nbetter with luminosity than stellar mass. The SHAM parameters of optically- and\nHI-selected galaxies are mutually exclusive, with the latter suggesting the\nimportance of properties beyond halo mass. We provide best-fit parameters for\nthe SHAM galaxy-halo connection as a function of each of our input choices,\nextending the domain of validity of the model while reducing potential\nsystematic error in its use." }, { "anchor": "Spectral Stacking of Radio-Interferometric Data: Mapping molecular line emission beyond the bright low-J CO transitions is\nstill challenging in extragalactic studies, even with the latest generation of\n(sub-)mm interferometers, such as ALMA and NOEMA. We summarise and test a\nspectral stacking method that has been used in the literature to recover\nlow-intensity molecular line emission, such as HCN(1-0), HCO+(1-0), and even\nfainter lines in external galaxies. The goal is to study the capabilities and\nlimitations of the stacking technique when applied to imaged interferometric\nobservations. The core idea of spectral stacking is to align spectra of the low\nS/N spectral lines to a known velocity field calculated from a higher S/N line\nexpected to share the kinematics of the fainter line, e.g., CO(1-0) or 21-cm\nemission. Then these aligned spectra can be coherently averaged to produce\npotentially high S/N spectral stacks. Here, we use imaged simulated\ninterferometric and total power observations at different signal-to-noise\nlevels, based on real CO observations. For the combined interferometric and\ntotal power data, we find that the spectral stacking technique is capable of\nrecovering the integrated intensities even at low S/N levels across most of the\nregion where the high S/N prior is detected. However, when stacking\ninterferometer-only data for low S/N emission, the stacks can miss up to 50% of\nthe emission from the fainter line. A key result of this analysis is that the\nspectral stacking method is able to recover the true mean line intensities in\nlow S/N cubes and to accurately measure the statistical significance of the\nrecovered lines. To facilitate the application of this technique we provide a\npublic Python package, called PyStacker.", "positive": "6-meter telescope observations of three dwarf spheroidal galaxies with\n very low surface brightness: Dwarf spheroidal galaxies (dSphs) are mostly investigated in the Local Group.\nDSphs are difficult targets for observations because of their small size and\nvery low surface brightness. Here we measure spectroscopic and photometric\nparameters of three candidates for isolated dSphs, KKH65=BTS23, KK180, and\nKK227, outside the Local Group. The galaxies are found to be of low metallicity\nand low velocity dispersion. They are among the lowest surface brightness\nobjects in the Local Universe. According to the measured radial velocities,\nmetallicities, and structural and photometric parameters, KKH65 and KK227 are\nrepresentatives of the ultra-diffuse quenched galaxies. KKH65 and KK227 belong\nto the outer parts of the groups NGC3414 and NGC5371, respectively. KK180 is\nlocated in the Virgo cluster infall region." }, { "anchor": "Photometric Calibration of the $[\u03b1/$Fe] Element: II. Calibration\n with SDSS Photometry: We present the calibration of the [$\\alpha/$Fe] element in terms of\nultra-violet excess for 465 dwarf stars with spectral type F0-K2. We used a\nsingle calibration, fitted to a third degree polynomial with a square of the\ncorrelation coefficient 0.74 and standard deviation 0.05 mag, for all stars due\nto their small colour range, $0.1<(g-r)_0\\leq 0.6$ mag, and high frequency in\nthe blueward of the spectrum which minimize the guillotine effect. Our\ncalibration provides [$\\alpha/$Fe] elements in the range $(-0.05, 0.35]$ dex.\nWe applied the procedure to a high-latitude field, $85^\\circ \\leq b \\leq\n90^\\circ$ with size 78 deg$^2$ and we could estimate the [$\\alpha/$Fe] elements\nof 23,414 dwarf stars which occupy a Galactic region up to a vertical distance\nof $z=9$ kpc. We could detect a small positive gradient, $d[\\alpha/{\\rm\nFe}]/dz=+0.032 \\pm0.002$ dex kpc$^{-1}$, for the range $0 10~\n\\rm Gyr$) owing to reionization-related quenching. More massive systems, in\ncontrast, all have late-time star formation. Our results suggest that $M_{\\rm\nhalo} \\simeq 5 \\times 10^9 M_{\\odot}$ is a probable dividing line between halos\nhosting reionization \"fossils\" and those hosting dwarfs that can continue to\nform stars in isolation after reionization.", "positive": "Jellyfish galaxies with the IllustrisTNG simulations -- Citizen-science\n results towards large distances, low-mass hosts, and high redshifts: We present the ``Cosmological Jellyfish'' project - a citizen-science\nclassification program to identify jellyfish galaxies within the IllustrisTNG\ncosmological simulations. Jellyfish (JF) are satellite galaxies that exhibit\nlong trailing gas features -- `tails' -- extending from their stellar body.\nTheir distinctive morphology arises due to ram-pressure stripping (RPS) as they\nmove through the background gaseous medium. Using the TNG50 and TNG100\nsimulations, we construct a sample of $\\sim 80,000$ satellite galaxies spanning\nan unprecedented range of stellar masses, $10^{8.3-12.3}\\,\\mathrm{M_\\odot}$,\nand host masses of $M_\\mathrm{200,c}=10^{10.4-14.6}\\,\\mathrm{M_\\odot}$ back to\n$z=2$ \\citep[extending the work of][]{yun_jellyfish_2019}. Based on this\nsample, $\\sim 90,000$ galaxy images were presented to volunteers in a\ncitizen-science project on the Zooniverse platform who were asked to determine\nif each galaxy image resembles a jellyfish. Based on volunteer votes, each\ngalaxy was assigned a score determining if it is a JF or not. This paper\ndescribes the project, the inspected satellite sample, the methodology, and the\nclassification process that resulted in a dataset of $5,307$\nvisually-identified jellyfish galaxies. We find that JF galaxies are common in\nnearly all group- and cluster-sized systems, with the JF fraction increasing\nwith host mass and decreasing with satellite stellar mass. We highlight JF\ngalaxies in three relatively unexplored regimes: low-mass hosts of\n$M_\\mathrm{200,c}\\sim10^{11.5-13}\\,\\mathrm{M_\\odot}$, radial positions within\nhosts exceeding the virial radius $R_\\mathrm{200,c}$, and at high redshift up\nto $z=2$. The full dataset of our jellyfish scores is publicly available and\ncan be used to select and study JF galaxies in the IllustrisTNG simulations." }, { "anchor": "New evidence for the ubiquity of prominent polar dust emission in AGN on\n tens of parsec scales: The key ingredient of active galactic nuclei (AGN) unification, the dusty\nobscuring torus was so far held responsible for the observed mid-infrared (MIR)\nemission of AGN. However, the best studied objects with VLTI/MIDI show that\ninstead a polar dusty wind is dominating these wavelengths, leaving little room\nfor a torus contribution. But is this wind an ubiquitous part of the AGN? To\ntest this, we conducted a straightforward detection experiment, using the\nupgraded VLT/VISIR for deep subarcsecond resolution MIR imaging of a sample of\nnine [O IV]-bright, obscured AGN, all of which were predicted to have\ndetectable polar emission. Indeed, the new data reveal such emission in all\nobjects but one. We further estimate lower limits on the extent of the polar\ndust and show that the polar dust emission is dominating the total MIR emission\nof the AGN. These findings support the scenario that polar dust is not only\nubiquitous in AGN but also an integral part of its structure, processing a\nsignificant part of the primary radiation. The polar dust has to be optically\nthin on average, which explains, e.g., the small dispersion in the observed\nmid-infrared--X-ray luminosity correlation. At the same time, it has to be\ntaken into account when deriving covering factors of obscuring material from\nmid-infrared to bolometric luminosity ratios. Finally, we find a new tentative\ntrend of increasing MIR emission size with increasing Eddington ratio.", "positive": "Effect of dynamical interactions on integrated properties of globular\n clusters: Globular Clusters (GCs) are generally treated as natural validators of simple\nstellar population (SSP) models. However, there are still some differences\nbetween real GCs and SSPs. In this work we use a direct $N$-body simulation\ncode {\\hf Nbody6} to study the influences of dynamical interactions,\nmetallicity and primordial binaries on Milky Way globular clusters' integrated\nproperties. Our models start with $N=100,000$ stars, covering a metallicity\nrange $Z=0.0001-0.02$, a subset of our models contain primordial binaries,\nresulting in a binary fraction as currently observed at a model age of\nGCs.Stellar evolution and external tidal field representative for an average\nMilky Way GC are taken into consideration. The integrated colours and Lick\nindices are calculated using BaSeL and Bluered stellar spectral libraries\nseparately.\n By including dynamical interactions, our model clusters show integrated\nfeatures (colours up to 0.01mag bluer, H$\\beta$ up to 0.1\\AA $ $ greater and\n[MgFe]$'$ 0.05\\AA $ $ smaller) making the clusters appear slightly younger than\nthe model clusters without dynamical interactions. This effect is caused mainly\nby the preferential loss of low-mass stars which have a stronger contribution\nto redder passbands as well as different spectral features compared to\nhigher-mass stars. In addition, this effect is larger at lower metallicities.\nOn the contrary, the incorporation of primordial binaries reduces this effect." }, { "anchor": "A critical look at the merger scenario to explain multiple populations\n and rotation in iron-complex globular clusters: Merging has been proposed to explain multiple populations in globular\nclusters (GCs) where there is a spread in iron abundance (hereafter,\niron-complex GCs). By means of N-body simulations, we investigate if merging is\nconsistent with the observations of sub-populations and rotation in\niron-complex GCs. The key parameters are the initial mass and density ratios of\nthe progenitors. When densities are similar, the more massive progenitor\ndominates the central part of the merger remnant and the less massive\nprogenitor forms an extended rotating population. The low-mass progenitor can\nbecome the majority population in the central regions of the merger remnant\nonly if its initial density is higher by roughly the mass ratio. To match the\nradial distribution of multiple populations in two iron-complex GCs ({\\omega}\nCen and NGC 1851), the less massive progenitor needs to be four times as dense\nas the larger one. Our merger remnants show solid-body rotation in the inner\nparts, becoming differential in the outer parts. Rotation velocity V and\nellipticity {\\epsilon} are in agreement with models for oblate rotators with\nisotropic dispersion. We discuss several kinematic signatures of a merger with\na denser lower mass progenitor that can be tested with future observations.", "positive": "HI-MaNGA: HI Followup for the MaNGA Survey: We present the HI-MaNGA programme of HI follow-up for the Mapping Nearby\nGalaxies at Apache Point Observatory (MaNGA) survey. MaNGA, which is part of\nthe Fourth phase of the Sloan Digital Sky Surveys (SDSS-IV), is in the process\nof obtaining integral field unit (IFU) spectroscopy for a sample of ~10,000\nnearby galaxies. We give an overview of the HI 21cm radio follow-up observing\nplans and progress and present data for the first 331 galaxies observed in the\n2016 observing season at the Robert C. Bryd Green Bank Telescope (GBT). We also\nprovide a cross match of the current MaNGA (DR15) sample with publicly\navailable HI data from the Arecibo Legacy Fast Arecibo L-band Feed Array\n(ALFALFA) survey. The addition of HI data to the MaNGA data set will strengthen\nthe survey's ability to address several of its key science goals that relate to\nthe gas content of galaxies, while also increasing the legacy of this survey\nfor all extragalactic science." }, { "anchor": "Spatially-resolved relation between [CI] $^{3}P_{1}$-$^{3}P_{0}$ and\n $^{12}$CO (1-0) in Arp 220: We present $\\sim$0.\"3 (114 pc) resolution maps of [CI]\n$^{3}P_{1}$-$^{3}P_{0}$ (hereafter [CI] (1-0)) and $^{12}$CO (1-0) obtained\ntoward Arp 220 with the Atacama Large Millimeter/submillimeter Array. The\noverall distribution of the [CI] (1-0) emission is consistent with the CO\n(1-0). While the [CI] (1-0) and CO (1-0) luminosities of the system follow the\nempirical linear relation for the unresolved ULIRG sample, we find a sublinear\nrelation between [CI] (1-0) and CO (1-0) using the spatially-resolved data. We\nmeasure the [CI] (1-0)/CO (1-0) luminosity ratio per pixel in star-forming\nenvironments of Arp 220 and investigate its dependence on the CO (3-2)/CO (1-0)\nratio ($R_{\\rm CO}$). On average, the [CI] (1-0)/CO (1-0) luminosity ratio is\nalmost constant up to $R_{\\rm CO} \\simeq 1$ and then increases with $R_{\\rm\nCO}$. According to the radiative transfer analysis, a high CI/CO abundance\nratio is required in regions with high [CI] (1-0)/CO (1-0) luminosity ratios\nand $R_{\\rm CO} > 1$, suggesting that the CI/CO abundance ratio varies at\n$\\sim$100 pc scale in Arp 220. The [CI] (1-0)/CO (1-0) luminosity ratio depends\non multiple factors and may not be straightforward to interpret. We also find\nthe high-velocity components traced by [CI] (1-0) in the western nucleus,\nlikely associated with the molecular outflow. The [CI] (1-0)/CO (1-0)\nluminosity ratio in the putative outflow is 0.87 $\\pm$ 0.28, which is four\ntimes higher than the average ratio of Arp 220. While there is a possibility\nthat the [CI] (1-0) and CO (1-0) emission traces different components, we\nsuggest that the high line ratios are likely because of elevated CI/CO\nabundance ratios based on our radiative transfer analysis. A CI-rich and\nCO-poor gas phase in outflows could be caused by the irradiation of the cosmic\nrays, the shock heating, and the intense radiation field.", "positive": "A low-luminosity type-1 QSO sample; III. Optical spectroscopic\n properties and activity classification: We report on the optical spectroscopic analysis of a sample of 99\nlow-luminosity quasi-stellar objects (LLQSOs) at $z\\leq 0.06$ base the\nHamburg/ESO QSO survey (HES). The LLQSOs presented here offer the possibility\nof studying the faint end of the QSO population at smaller cosmological\ndistances and, therefore, in greater detail. A small number of our LLQSO\npresent no broad component. Two sources show double broad components, whereas\nsix comply with the classic NLS1 requirements. As expected in NLR of broad line\nAGNs, the [S{\\sc{ii}}]$-$based electron density values range between 100 and\n1000 N$_{e}$/cm$^{3}$. Using the optical characteristics of Populations A and\nB, we find that 50\\% of our sources with H$\\beta$ broad emission are consistent\nwith the radio-quiet sources definition. The remaining sources could be\ninterpreted as low-luminosity radio-loud quasar. The BPT-based classification\nrenders an AGN/Seyfert activity between 50 to 60\\%. For the remaining sources,\nthe possible star burst contribution might control the LINER and HII\nclassification. Finally, we discuss the aperture effect as responsible for the\ndifferences found between data sets, although variability in the BLR could play\na significant role as well." }, { "anchor": "Redshift Evolution of the H2/HI Mass Ratio In Galaxies: In this paper we present an attempt to estimate the redshift evolution of the\nmolecular to neutral gas mass ratio within galaxies (at fixed stellar mass).\nFor a sample of five nearby grand design spirals located on the Main Sequence\n(MS) of star forming galaxies, we exploit maps at 500 pc resolution of stellar\nmass and star formation rate ($M_{\\star}$ and SFR). For the same cells, we also\nhave estimates of the neutral ($M_{\\rm HI}$) and molecular ($M_{\\rm H_2}$) gas\nmasses. To compute the redshift evolution we exploit two relations: {\\it i)}\none between the molecular-to-neutral mass ratio and the total gas mass ($M_{\\rm\ngas}$), whose scatter shows a strong dependence with the distance from the\nspatially resolved MS, and {\\it ii)} the one between\n$\\log(M_{\\rm{H_2}}/M_{\\star})$ and $\\log(M_{\\rm{HI}}/M_{\\star})$. For both\nmethods, we find that $M_{\\rm H_2}$/$M_{\\rm HI}$ within the optical radius\nslightly decreases with redshift, contrary to common expectations of galaxies\nbecoming progressively more dominated by molecular hydrogen at high redshifts.\nWe discuss possible implications of this trend on our understanding of the\ninternal working of high redshift galaxies.", "positive": "Mechanochemical synthesis of Aromatic Infrared Band carriers. The\n top-down chemistry of interstellar carbonaceous dust grain analogues: Interstellar space hosts nanometre- to micron-sized dust grains. The\ncarbonaceous-rich component of these grain populations emits in infrared bands,\nobserved remotely for decades with telescopes and satellites. They are a key\ningredient of astrochemical dust evolution. The precise carriers for most of\nthese bands are still unknown and not well reproduced in the laboratory. In\nthis work, we show the high-energy mechanochemical synthesis of disordered\naromatic and aliphatic analogues provides interstellar relevant dust particles.\nThe mechanochemical milling of carbon-based solids under a hydrogen atmosphere\nproduces particles with a spectroscopic match to astrophysical observations of\naromatic infrared band (AIB) emission. The H/C ratio for the analogues that\nbest reproduce these astronomical infrared observations lies in the 5$\\pm$2%\nrange. This value is much lower than diffuse interstellar hydrogenated\namorphous carbons, another Galactic dust grain component observed in\nabsorption, and it most probably provides a constraint on the hydrogenation\ndegree of the most aromatic carbonaceous dust grain carriers. A broad band,\nobserved in AIBs, in the 7.4-8.3 $\\mu$m range is correlated to the hydrogen\ncontent, and thus the structural evolution in the analogues produced. The\nmechanochemical process can be seen as an experimental reactor to stimulate\nlocal energetic chemical reactions. It introduces bond disorder and hydrogen\nchemical attachment on the produced defects, with an effect similar to the\ninterstellar space very localised chemical reactions with solids. From the\nvantage point of astrophysics, these laboratory interstellar dust analogues\nwill be used to predict dust grain evolution under simulated interstellar\nconditions, including harsh radiative environments. Such interstellar analogues\noffer an opportunity to derive a global view on the cycling of matter in other\nstar forming systems." }, { "anchor": "Dust models compatible with Planck intensity and polarization data in\n translucent lines of sight: The dust properties inferred from the analysis of Planck observations in\ntotal and polarized emission challenge current dust models. We propose new dust\nmodels compatible with polarized and unpolarized data in extinction and\nemission for translucent lines of sight ($0.5 < A_V < 2.5$). We amended the\nDustEM tool to model polarized extinction and emission. We fit the spectral\ndependence of the mean extinction, polarized extinction, SED and polarized SED\nwith PAHs, astrosilicates and amorphous carbon (a-C). The astrosilicate\npopulation is aligned along the magnetic field lines, while the a-C population\nmay be aligned or not. With their current optical properties, oblate\nastrosilicate grains are not emissive enough to reproduce the emission to\nextinction polarization ratio $P_{353}/p_V$ derived with Planck data. Models\nusing prolate astrosilicate grains with an elongation $a/b=3$ and an inclusion\nof 20% of porosity succeed. The spectral dependence of the polarized SED is\nsteeper in our models than in the data. Models perform slightly better when a-C\ngrains are aligned. A small (6%) volume inclusion of a-C in the astrosilicate\nmatrix removes the need for porosity and perfect grain alignment, and improves\nthe fit to the polarized SED. Dust models based on astrosilicates can be\nreconciled with Planck data by adapting the shape of grains and adding\ninclusions of porosity or a-C in the astrosilicate matrix.", "positive": "Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies:\n Black Hole Scaling Relations Are Not Biased by Selection Effects: The oral version of this paper summarized Kormendy & Ho 2013, ARA&A, 51, 511.\nHowever, earlier speakers at this Symposium worried that selection effects bias\nthe derivation of black hole scaling relations. I therefore added -- and this\nproceedings paper emphasizes -- a discussion of why we can be confident that\nselection effects do not bias the observed correlations between BH mass M_BH\nand the luminosity, stellar mass, and velocity dispersion of host ellipticals\nand classical bulges. These are the only galaxy components that show tight\nBH-host correlations. The scatter plots of M_BH with host properties for\npseudobulges and disks are upper envelopes of scatter that does extend to lower\nBH masses. BH correlations are most consistent with a picture in which BHs\ncoevolve only with classical bulges and ellipticals. Four physical regimes of\ncoevolution (or not) are suggested by Kormendy & Ho 2013 and are summarized\nhere." }, { "anchor": "The Unusual Galactic Center Radio Source N3: Here we report on new, multi-wavelength radio observations of the unusual\npoint source \"N3\" that appears to be located in the vicinity of the Galactic\nCenter. VLA observations between 2 and 50 GHz reveal that N3 is a compact and\nbright source (56 mJy at 10 GHz) with a non-thermal spectrum superimposed upon\nthe non-thermal radio filaments (NTFs) of the Radio Arc. Our highest frequency\nobservations place a strict upper limit of 65 x 28 mas on the size of N3. We\ncompare our observations to those of Yusef-Zadeh & Morris (1987) and Lang et\nal. (1997) and conclude that N3 is variable over long time scales.\nAdditionally, we present the detection of a compact molecular cloud located\nadjacent to N3 in projection. CH3CN, CH3OH, CS, HC3N, HNCO, SiO, SO, and NH3\nare detected in the cloud and most transitions have FWHM line widths of ~20\nkm/s. The rotational temperature determined from the metastable NH3 transitions\nranges from 79 K to 183 K depending on the transitions used. We present\nevidence that this molecular cloud is interacting with N3. After exploring the\nrelationship between the NTFs, molecular cloud, and N3, we conclude that N3\nlikely lies within the Galactic Center. We are able to rule out the HII region,\nyoung supernova, active star, AGN, and micro-quasar hypotheses for N3. While a\nmicro-blazar may provide a viable explanation for N3, additional observations\nare needed to determine the physical counterpart of this mysterious source.", "positive": "CN Zeeman observations of the NGC 2264-C protocluster: From an observational point of view, the role of magnetic fields in star\nformation remains unclear, and two main theoretical scenarios have been\nproposed so far to regulate the star-formation processes. The first model\nassumes that turbulence in star-forming clumps plays a crucial role, and\nespecially that protostellar outflow-driven turbulence is crucial to support\ncluster-forming clumps; while the second scenario is based on the consideration\nof a magnetically-supported clump. Previous studies of the NGC 2264-C\nprotocluster indicate that, in addition to thermal pressure, some extra support\nmight effectively act against the gravitational collapse of this\ncluster-forming clump. We previously showed that this extra support is not due\nto the numerous protostellar outflows, nor the enhanced turbulence in this\nprotocluster. Here we present the results of the first polarimetric campaign\ndedicated to quantifying the magnetic support at work in the NGC 2264-C clump.\nOur Zeeman observations of the CN(1-0) hyperfine lines provide an upper limit\nto the magnetic field strength B_los \\leq0.6 mG in the protocluster (projected\nalong the line of sight). While these results do not provide sufficiently tight\nconstraints to fully quantify the magnetic support at work in NGC 2264-C, they\nsuggest that, within the uncertainties, the core could be either magnetically\nsuper or sub-critical, with the former being more likely." }, { "anchor": "Evaporating Very Small Grains as tracers of the UV radiation field in\n Photo-dissociation Regions: Context. In photo-dissociation regions (PDRs), Polycyclic Aromatic\nHydrocarbons (PAHs) could be produced by evaporation of Very Small Grains\n(VSGs) by the impinging UV radiation field from a nearby star. Aims. We\ninvestigate quantitatively the transition zone between evaporating Very Small\nGrains (eVSGs) and PAHs in several PDRs. Methods. We study the relative\ncontribution of PAHs and eVSGs to the mid-IR emission in a wide range of\nexcitation conditions. We fit the observed mid-IR emission of PDRs by using a\nset of template band emission spectra of PAHs, eVSGs and gas lines. The fitting\ntool PAHTAT (PAH Toulouse Astronomical Templates) is made available to the\ncommunity as an IDL routine. From the results of the fit, we derive the\nfraction of carbon f_eVSG locked in eVSGs and compare it to the intensity of\nthe local UV radiation field. Results. We show a clear decrease of f_eVSG with\nincreasing intensity of the local UV radiation field, which supports the\nscenario of photo-destruction of eVSGs. Conversely, this dependence can be used\nto quantify the intensity of the UV radiation field for different PDRs,\nincluding non resolved ones. Conclusions. PAHTAT can be used to trace the\nintensity of the local UV radiation field in regions where eVSGs evaporate,\nwhich correspond to relatively dense (nH = [100, 10^5 ] cm-3) and UV irradiated\nPDRs (G0 = [100, 5x10^4]) where H2 emits in rotational lines.", "positive": "Organic chemistry in the protosolar analogue HOPS-108: Environment\n matters: Hot corinos are compact regions around solar-mass protostellar objects that\nare very rich in interstellar complex organic molecules (iCOMs). They are\nbelieved to represent the very early phases of our Solar System's birth, which\nwas very likely also characterized by rich organic chemistry. While most of the\nstudied hot corinos are either isolated or born in a loose protocluster, our\nSun was born in a densely packed star cluster, near massive stars whose\nultraviolet radiation must have contributed to shaping the evolution of the\nsurrounding environment. In addition, internal irradiation from energetic\nparticles ($>$10 Mev), whose imprint is seen today in the products of\nshort-lived radionuclides in meteoritic material, is also known to have\noccurred during the Solar System formation. How did all these conditions affect\nthe chemistry of the proto-Sun and its surroundings is still an open question.\nTo answer this question, we studied HOPS-108, the hot corino located in the\nprotosolar analogue OMC-2 FIR4. The study was carried out with ALMA at 1.3mm\nwith an angular resolution of $\\sim$100 AU. We detected 11 iCOMs such as\nCH$_{3}$OH HCOOCH$_{3}$ and CH$_{3}$OCH$_{3}$. Our results can be summarized as\nfollows: (1) an enhancement of HCOOCH3 with respect to other hot corinos, (2) a\n[CH$_{3}$OCH$_{3}$]/[HCOOCH$_{3}$] abundance ratio of $\\sim$0.2 marginally\ndeviating from the usual trend seen in other sources\n([CH$_{3}$OCH$_{3}$]/[HCOOCH$_{3}$] $\\sim$1), (3) a [CH$_{2}$DOH]/[CH$_{3}$OH]\nratio of 2.5\\% which is lower than what is seen in Perseus and Ophiuchus hot\ncorinos ($\\sim$7\\%-9\\%) and similar to that seen in HH212 another source\nlocated in Orion. This might result from different physical conditions in the\nOrion molecular complex compared to other regions." }, { "anchor": "The impact of early massive mergers on the chemical evolution of Milky\n Way-like galaxies: insights from NIHAO-UHD simulations: Recent observations of the Milky Way (MW) found an unexpected steepening of\nthe star-forming gas metallicity gradient around the time of the\nGaia-Sausage-Enceladus (GSE) merger event. Here we investigate the influence of\nearly ($t_{\\mathrm{merger}}\\lesssim5$ Gyr) massive\n($M_{\\mathrm{gas}}^{\\mathrm{merger}}/M_{\\mathrm{gas}}^{\\mathrm{main}}(t_{\\mathrm{merger}})\\gtrsim10\\%$)\nmerger events such as the Gaia-Sausage Enceladus merger in the MW on the\nevolution of the cold gas metallicity gradient. We use the NIHAO-UHD suite of\ncosmological hydrodynamical simulations of MW-mass galaxies to study the\nfrequency of massive early mergers and their detailed impact on the morphology\nand chemistry of the gaseous disks. We find a strong steepening of the\nmetallicity gradient at early times for all four galaxies in our sample which\nis caused by a sudden increase in the cold gas disk size (up to a factor of 2)\nin combination with the supply of un-enriched gas ($\\sim0.75$ dex lower\ncompared to the main galaxy) by the merging dwarf galaxies. The mergers mostly\naffect the galaxy outskirts and lead to an increase in cold gas surface density\nof up to 200% outside of $\\sim8$ kpc. The addition of un-enriched gas breaks\nthe self-similar enrichment of the inter-stellar-medium and causes a dilution\nof the cold gas in the outskirts of the galaxies. The accreted stars and the\nones formed later out of the accreted gas inhabit distinct tracks offset to\nlower [$\\alpha$/Fe] and [Fe/H] values compared to the main galaxy's stars. We\nfind that such mergers can contribute significantly to the formation of a\nsecond, low-$\\alpha$ sequence as is observed in the MW.", "positive": "Kinematical Analysis of Substructure in the Southern Periphery of the\n Large Magellanic Cloud: We report the first 3-D kinematical measurements of 88 stars in the direction\nof several recently discovered substructures in the southern periphery of the\nLarge Magellanic Cloud (LMC) using a combination of Gaia proper motions and\nradial velocities from the APOGEE-2 survey. More specifically, we explore stars\nlie in assorted APOGEE-2 pointings in a region of the LMC periphery where\nvarious overdensities of stars have previously been identified in maps of stars\nfrom Gaia and DECam. By using a model of the LMC disk rotation, we find that a\nsizeable fraction of the APOGEE-2 stars have extreme space velocities that are\ndistinct from, and not a simple extension of, the LMC disk. Using N-body\nhydrodynamical simulations of the past dynamical evolution and interaction of\nthe LMC and Small Magellanic Cloud (SMC), we explore whether the extreme\nvelocity stars may be accounted for as tidal debris created in the course of\nthat interaction. We conclude that the combination of LMC and SMC debris\nproduced from their interaction is a promising explanation, although we cannot\nrule out other possible origins, and that these new data should be used to\nconstrain future simulations of the LMC-SMC interaction. We also conclude that\nmany of the stars in the southern periphery of the LMC lie out of the LMC plane\nby several kpc. Given that the metallicity of these stars suggest they are\nlikely of Magellanic origin, our results suggest that a wider exploration of\nthe past interaction history of the Magellanic Clouds is needed." }, { "anchor": "Galaxy And Mass Assembly (GAMA): The Dependence of Star Formation on\n Surface Brightness in Low Redshift Galaxies: The star formation rate in galaxies is well known to correlate with stellar\nmass (the `star-forming main sequence'). Here we extend this further to explore\nany additional dependence on galaxy surface brightness, a proxy for stellar\nmass surface density. We use a large sample of low redshift ($z \\leq 0.08$)\ngalaxies from the GAMA survey which have both SED derived star formation rates\nand photometric bulge-disc decompositions, the latter providing measures of\ndisc surface brightness and disc masses. Using two samples, one of galaxies\nfitted by a single component with S\\'{e}rsic index below 2 and one of the discs\nfrom two-component fits, we find that once the overall mass dependence of star\nformation rate is accounted for, there is no evidence in either sample for a\nfurther dependence on stellar surface density.", "positive": "Galaxy And Mass Assembly (GAMA): Stellar mass functions by Hubble type: We present an estimate of the galaxy stellar mass function and its division\nby morphological type in the local (0.025 < z < 0.06) Universe. Adopting robust\nmorphological classifications as previously presented (Kelvin et al.) for a\nsample of 3,727 galaxies taken from the Galaxy And Mass Assembly survey, we\ndefine a local volume and stellar mass limited sub-sample of 2,711 galaxies to\na lower stellar mass limit of M = 10^9.0 M_sun. We confirm that the galaxy\nstellar mass function is well described by a double Schechter function given by\nM* = 10^10.64 M_sun, {\\alpha}1 = -0.43, {\\phi}*1 = 4.18 dex^-1 Mpc^-3,\n{\\alpha}2 = -1.50 and {\\phi}*2 = 0.74 dex^-1 Mpc^-3. The constituent\nmorphological-type stellar mass functions are well sampled above our lower\nstellar mass limit, excepting the faint little blue spheroid population of\ngalaxies. We find approximately 71+3-4% of the stellar mass in the local\nUniverse is found within spheroid dominated galaxies; ellipticals and S0-Sas.\nThe remaining 29+4-3% falls predominantly within late type disk dominated\nsystems, Sab-Scds and Sd-Irrs. Adopting reasonable bulge-to-total ratios\nimplies that approximately half the stellar mass today resides in spheroidal\nstructures, and half in disk structures. Within this local sample, we find\napproximate stellar mass proportions for E : S0-Sa : Sab-Scd : Sd-Irr of 34 :\n37 : 24 : 5." }, { "anchor": "A possible influence on standard model of quasars and active galactic\n nuclei in strong magnetic field: Recent observational evidence indicates that the center of our Milky Way\nharbours a super-massive object with ultra-strong radial magnetic field\n(Eatough et al., 2013). Here we demonstrate that the radiations observed in the\nvicinity of the Galactic Center (GC) (Falcke and Marko 2013) cannot be emitted\nby the gas of the accretion disk since the accreting plasma is prevented from\napproaching to the GC by the abnormally strong radial magnetic field. These\nfields obstruct the infalling accretion flow from the inner region of the disk\nand the central massive black hole in the standard model. It is expected that\nthe observed radiations near the Galactic Center cannot be generated by the\ncentral black hole.\n We also demonstrate that the observed ultra-strong radial magnetic field near\nthe Galactic Center ( Eatough et al., 2013) cannot be generated by the -\nturbulence dynamo mechanism of Parker since preliminary qualitative estimate in\nterms of this mechanism gives a magnetic field strength six orders of magnitude\nsmaller than the observed field strength at . However, both these difficulties\nor the dilemma of the standard model can be overcome if the central black hole\nin the standard model is replaced by a supper-massive stellar object containing\nmagnetic monopoles ( SMSOMM, Peng and Chou, 2001). The observed power peaking\nof the thermal radiation is essentially the same as our theoretical prediction.\nIn addition, the discovery of the ultra-strong radial magnetic field near the\nGalactic Center can be naturally explained and is consistent with the\nprediction of our model( Peng and Chou 2001). Furthermore, the observed\nultra-strong radial magnetic field in the vicinity of the Galactic Center may\nbe considered as the astronomical evidence for the existence of magnetic\nmonopoles as predicted by the Grand Unified Theory of particle physics.", "positive": "The APEX-CHAMP+ view of the Orion Molecular Cloud 1 core - Constraining\n the excitation with submillimeter CO multi-line observations: A high density portion of the Orion Molecular Cloud 1 (OMC-1) contains the\nprominent, warm Kleinmann-Low (KL) nebula that is internally powered by an\nenergetic event plus a farther region in which intermediate to high mass stars\nare forming. Its outside is affected by ultraviolet radiation from the\nneighboring Orion Nebula Cluster and forms the archetypical photon-dominated\nregion (PDR) with the prominent bar feature. Its nearness makes the OMC-1 core\nregion a touchstone for research on the dense molecular interstellar medium and\nPDRs. Using the Atacama Pathfinder Experiment telescope (APEX), we have imaged\nthe line emission from the multiple transitions of several carbon monoxide (CO)\nisotopologues over the OMC-1 core region. Our observations employed the 2x7\npixel submillimeter CHAMP+ array to produce maps (~ 300 arcsec x 350 arcsec) of\n12CO, 13CO, and C18O from mid-J transitions (J=6-5 to 8-7). We also obtained\nthe 13CO and C18O J=3-2 images toward this region. The 12CO line emission shows\na well-defined structure which is shaped and excited by a variety of phenomena,\nincluding the energetic photons from hot, massive stars in the nearby Orion\nNebula's central Trapezium cluster, active high- and intermediate-mass star\nformation, and a past energetic event that excites the KL nebula. Radiative\ntransfer modeling of the various isotopologic CO lines implies typical H2\ndensities in the OMC-1 core region of ~10^4-10^6 cm^-3 and generally elevated\ntemperatures (~ 50-250 K). We estimate a warm gas mass in the OMC-1 core region\nof 86-285 solar masses." }, { "anchor": "Nowhere to Hide: Radio-faint AGN in the GOODS-N field. II.\n Multi-wavelength AGN selection techniques and host galaxy properties: Obtaining a census of active galactic nuclei (AGN) activity across cosmic\ntime is critical to our understanding of galaxy evolution and formation. Many\nAGN classification techniques are compromised by dust obscuration. However,\nvery long baseline interferometry (VLBI) can be used to identify compact\nemission that can only be attributed to AGN activity.\n This is the second in a series of papers dealing with the compact radio\npopulation in the GOODS-N field. We review 14 different AGN classification\ntechniques in the context of a VLBI-detected sample, and use these to\ninvestigate the nature of the AGN as well as their host galaxies.\n We find that no single identification technique can identify all VLBI objects\nas AGN. Infrared colour-colour selection is most notably incomplete. However,\nthe usage of multiple classification schemes can identify all VLBI-selected\nAGN, independently verifying similar approaches used in other deep field\nsurveys. In the era of large area surveys with instruments such as the SKA and\nngVLA, multi-wavelength coverage, which relies heavily upon observations from\nspace, is often unavailable. Therefore, VLBI remains an integral component in\ndetecting AGN of the jetted efficient and inefficient accretion types. A\nsubstantial fraction (46%) of the VLBI AGN have no X-ray counterpart, which is\nmost likely due to lack of sensitivity in the X-ray band. A high fraction of\nthe VLBI AGN reside in low or intermediate redshift dust-poor early-type\ngalaxies. These most likely exhibit inefficient accretion. Finally, a\nsignificant fraction of the VLBI AGN reside in symbiotic dusty starburst - AGN\nsystems. We present an extensive compilation of the multi-wavelength properties\nof all the VLBI-selected AGN in GOODS-N in the Appendix.", "positive": "Detecting Direct Collapse Black Holes: making the case for CR7: We propose that one of the sources in the recently detected system CR7 by\nSobral et al. (2015) through spectro-photometric measurements at $z = 6.6$\nharbors a direct collapse blackhole (DCBH). We argue that the LW radiation\nfield required for direct collapse in source A is provided by sources B and C.\nBy tracing the LW production history and star formation rate over cosmic time\nfor the halo hosting CR7 in a $\\Lambda$CDM universe, we demonstrate that a DCBH\ncould have formed at $z\\sim 20$. The spectrum of source A is well fit by\nnebular emission from primordial gas around a BH with MBH $\\sim 4.4 \\times 10^6\n\\ \\rm M_{\\odot}$ accreting at a 40 % of the Eddington rate, which strongly\nsupports our interpretation of the data. Combining these lines of evidence, we\nargue that CR7 might well be the first DCBH candidate." }, { "anchor": "Have proto-planetary discs formed planets?: It has recently been noted that many discs around T Tauri stars appear to\ncomprise only a few Jupiter-masses of gas and dust. Using millimetre surveys of\ndiscs within six local star-formation regions, we confirm this result, and find\nthat only a few percent of young stars have enough circumstellar material to\nbuild gas giant planets, in standard core accretion models. Since the frequency\nof observed exo-planets is greater than this, there is a `missing mass'\nproblem. As alternatives to simply adjusting the conversion of dust-flux to\ndisc mass, we investigate three other classes of solution. Migration of planets\ncould hypothetically sweep up the disc mass reservoir more efficiently, but\ntrends in multi-planet systems do not support such a model, and theoretical\nmodels suggest that the gas accretion timescale is too short for migration to\nsweep the disc. Enhanced inner-disc mass reservoirs are possible, agreeing with\npredictions of disc evolution through self-gravity, but not adding to\nmillimetre dust-flux as the inner disc is optically thick. Finally, the\nincidence of massive discs is shown to be higher at the {\\it proto}stellar\nstages, Classes 0 and I, where discs substantial enough to form planets via\ncore accretion are abundant enough to match the frequency of exo-planets.\nGravitational instability may also operate in the Class 0 epoch, where half the\nobjects have potentially unstable discs of $\\ga$30 % of the stellar mass.\nHowever, recent calculations indicate that forming gas giants inside 50 AU by\ninstability is unlikely, even in such massive discs. Overall, the results\npresented suggest that the canonically 'proto-planetary' discs of Class II T\nTauri stars {\\bf have globally low masses in dust observable at millimetre\nwavelengths, and conversion to larger bodies (anywhere from small rocks up to\nplanetary cores) must already have occurred.}", "positive": "Models for the 3-D axisymmetric gravitational potential of the Milky Way\n Galaxy - A detailed modelling of the Galactic disk: Aims. Galaxy mass models based on simple and analytical functions for the\ndensity and potential pairs have been widely proposed in the literature. Disk\nmodels constrained by kinematic data alone give information on the global disk\nstructure only very near the Galactic plane. We attempt to circumvent this\nissue by constructing disk mass models whose three-dimensional structures are\nconstrained by a recent Galactic star counts model in the near-infrared and\nalso by observations of the hydrogen distribution in the disk. Our main aim is\nto provide models for the gravitational potential of the Galaxy that are fully\nanalytical but also with a more realistic description of the density\ndistribution in the disk component. Methods. From the disk model directly based\non the observations (here divided into the thin and thick stellar disks and the\nHI and H$_2$ disks subcomponents), we produce fitted mass models by combining\nthree Miyamoto-Nagai disk profiles of any \"model order\" (1, 2, or 3) for each\ndisk subcomponent. The Miyamoto-Nagai disks are combined with models for the\nbulge and \"dark halo\" components and the total set of parameters is adjusted by\nobservational kinematic constraints. A model which includes a ring density\nstructure in the disk, beyond the solar Galactic radius, is also investigated.\nResults. The Galactic mass models return very good matches to the imposed\nobservational constraints. In particular, the model with the ring density\nstructure provides a greater contribution of the disk to the rotational support\ninside the solar circle. The gravitational potential models and their\nassociated force-fields are described in analytically closed forms, and in\naddition, they are also compatible with our best knowledge of the stellar and\ngas distributions in the disk component. The gravitational potential models are\nsuited for investigations of orbits in the Galactic disk." }, { "anchor": "Bondi-Hoyle-Littleton accretion and the upper mass stellar IMF: We report on a series of numerical simulations of gas clouds with\nself-gravity forming sink particles, adopting an isothermal equation of state\nto isolate the effects of gravity from thermal physics on the resulting sink\nmass distributions. Simulations starting with supersonic velocity fluctuations\ndevelop sink mass functions with a high-mass power-law tail $dN/d\\log M \\propto\nM^{\\Gamma}$, $\\Gamma = -1 \\pm 0.1$, independent of the initial Mach number of\nthe velocity field. Similar results but with weaker statistical significance\nhold for a simulation starting with initial density fluctuations. This mass\nfunction power-law dependence agrees with the asymptotic limit found by\nZinnecker assuming Bondi-Hoyle-Littleton (BHL) accretion, even though the mass\naccretion rates of individual sinks show significant departures from the\npredicted $\\mdot \\propto M^2$ behavior. While BHL accretion is not strictly\napplicable due to the complexity of the environment, we argue that the final\nmass functions are the result of a {\\em relative} $M^2$ dependence resulting\nfrom gravitationally-focused accretion. Our simulations may show the power-law\nmass function particularly clearly compared with others because our adoption of\nan isothermal equation of state limits the effects of thermal physics in\nproducing a broad initial fragmentation spectrum; $\\Gamma \\rightarrow -1$ is an\nasymptotic limit found only when sink masses grow well beyond their initial\nvalues. While we have purposely eliminated many additional physical processes\n(radiative transfer, feedback) which can affect the stellar mass function, our\nresults emphasize the importance of gravitational focusing for massive star\nformation.", "positive": "Digging deeper into the Southern skies: a compact Milky-Way companion\n discovered in first-year Dark Energy Survey data: The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern\nhemisphere, which is rapidly reducing the existing north-south asymmetry in the\ncensus of MW satellites and other stellar substructure. We use the first-year\nDES data down to previously unprobed photometric depths to search for stellar\nsystems in the Galactic halo, therefore complementing the previous analysis of\nthe same data carried out by our group earlier this year. Our search is based\non a matched filter algorithm that produces stellar density maps consistent\nwith stellar population models of various ages, metallicities, and distances\nover the survey area. The most conspicuous density peaks in these maps have\nbeen identified automatically and ranked according to their significance and\nrecurrence for different input models. We report the discovery of one\nadditional stellar system besides those previously found by several authors\nusing the same first-year DES data. The object is compact, and consistent with\nbeing dominated by an old and metal-poor population. DES J0034-4902 is found at\nhigh significance and appears in the DES images as a compact concentration of\nfaint blue point sources at ~ 87 {kpc}. Its half-light radius of r_h = 9.88 +/-\n4.31 {pc} and total luminosity of M_V ~ -3.05_{-0.42}^{+0.69} are consistent\nwith it being a low mass halo cluster. It is also found to have a very\nelongated shape. In addition, our deeper probe of DES 1st year data confirms\nthe recently reported satellite galaxy candidate Horologium II as a significant\nstellar overdensity. We also infer its structural properties and compare them\nto those reported in the literature." }, { "anchor": "Velocity-inverted three-dimensional distribution of the gas clouds in\n the Type 2 AGN NGC1068: Spatially-resolved velocity maps at high resolutions of 1-10 pc are becoming\navailable for many nearby AGNs in both optical/infrared atomic emission lines\nand sub-mm molecular lines. For the former, it has been known that a linear\nrelationship appears to exist between the velocity of the ionized gas clouds\nand the distance from the nucleus in the inner ~100 pc region, where these\nclouds are outflowing. Here we demonstrate that, in such a case, we can\nactually derive the three-dimensional (3D) geometrical distribution of the\nclouds directly from the velocity map. Revisiting such a velocity map taken by\nHST for the prototypical Type 2 AGN NGC1068, we implement the visualization of\nthe 3D distribution derived from the map, and show that this inner narrow-line\nregion has indeed a hollow-cone structure, consistent with previous modeling\nresults. Quite possibly, this is the outer extended part of the polar elongated\ndusty material seen in the recent mid-IR interferometry at pc scale.\nConversely, the latter small-scale geometry is inferred to have a hollow-cone\noutflowing structure as the inward extension of the derived 3D distribution\nabove. The AGN obscuring \"torus\" is argued to be the inner optically thick part\nof this hollow-cone outflow, and its shadowed side would probably be associated\nwith the molecular outflow seen in certain sub-mm lines. We discuss the nature\nof the linear velocity field, which could be from an episodic acceleration that\nhad occurred ~10^5 years ago.", "positive": "Building the Stellar Halo Through Feedback in Dwarf Galaxies: We present a new model for the formation of stellar halos in dwarf galaxies.\nWe demonstrate that the stars and star clusters that form naturally in the\ninner regions of dwarfs are expected to migrate from the gas rich, star forming\ncentre to join the stellar spheroid. For dwarf galaxies, this process could be\nthe dominant source of halo stars. The effect is caused by stellar\nfeedback-driven bulk motions of dense gas which, by causing potential\nfluctuations in the inner regions of the halo, couple to all collisionless\ncomponents. This effect has been demonstrated to generate cores in otherwise\ncuspy cold dark matter profiles and is particularly effective in dwarf galaxy\nhaloes. It can build a stellar spheroid with larger ages and lower\nmetallicities at greater radii without requiring an outside-in formation model.\nGlobular cluster-type star clusters can be created in the galactic ISM and then\nmigrate to the spheroid on 100\\thinspace Myr timescales. Once outside the inner\nregions they are less susceptible to tidal disruption and are thus long lived;\nclusters on wider orbits may be easily unbound from the dwarf to join the halo\nof a larger galaxy during a merger. A simulated dwarf galaxy\n($\\text{M}_{vir}\\simeq10^{9}\\text{M}_{\\odot}$ at $z=5$) is used to examine this\ngravitational coupling to dark matter and stars." }, { "anchor": "The impact of human expert visual inspection on the discovery of strong\n gravitational lenses: We investigate the ability of human 'expert' classifiers to identify strong\ngravitational lens candidates in Dark Energy Survey like imaging. We recruited\na total of 55 people that completed more than 25$\\%$ of the project. During the\nclassification task, we present to the participants 1489 images. The sample\ncontains a variety of data including lens simulations, real lenses, non-lens\nexamples, and unlabeled data. We find that experts are extremely good at\nfinding bright, well-resolved Einstein rings, whilst arcs with $g$-band\nsignal-to-noise less than $\\sim$25 or Einstein radii less than $\\sim$1.2 times\nthe seeing are rarely recovered. Very few non-lenses are scored highly. There\nis substantial variation in the performance of individual classifiers, but they\ndo not appear to depend on the classifier's experience, confidence or academic\nposition. These variations can be mitigated with a team of 6 or more\nindependent classifiers. Our results give confidence that humans are a reliable\npruning step for lens candidates, providing pure and quantifiably complete\nsamples for follow-up studies.", "positive": "Evidence for Ultra-Diffuse Galaxy Formation Through Tidal Heating of\n Normal Dwarfs: We have followed up two ultra-diffuse galaxies (UDGs), detected adjacent to\nstellar streams, with Hubble Space Telescope (HST) imaging and HI mapping with\nthe Jansky Very Large Array (VLA) in order to investigate the possibility that\nthey might have a tidal origin. With the HST F814W and F555W images we measure\nthe globular cluster (GC) counts for NGC 2708-Dw1 and NGC 5631-Dw1 as\n$2^{+1}_{-1}$ and $5^{+1}_{-2}$, respectively. NGC 2708-Dw1 is undetected in HI\ndown to a 3$\\sigma$ limit of $\\log (M_\\mathrm{HI}/\\mathrm{M_\\odot}) = 7.3$, and\nthere is no apparent HI associated with the nearby stellar stream. There is a\n2$\\sigma$ HI feature coincident with NGC 5631-Dw1. However, this emission is\nblended with a large gaseous tail emanating from NGC 5631 and is not\nnecessarily associated with the UDG. The presence of any GCs and the lack of\nclear HI connections between the UDGs and their parent galaxies strongly\ndisfavor a tidal dwarf galaxy origin, but cannot entirely rule it out. The GC\ncounts are consistent with those of normal dwarf galaxies, and the most\nprobable formation mechanism is one where these UDGs were born as normal dwarfs\nand were later tidally stripped and heated. We also identify an over-luminous\n($M_\\mathrm{V} = -11.1$) GC candidate in NGC 2708-Dw1, which may be a nuclear\nstar cluster transitioning to an ultra-compact dwarf as the surrounding dwarf\ngalaxy gets stripped of stars." }, { "anchor": "Early formation and recent starburst activity in the nuclear disc of the\n Milky Way: The nuclear disc is a dense stellar structure at the centre of the Milky Way,\nwith a radius of $\\sim$150 pc. It has been a place of intense star formation in\nthe past several tens of millions of years but its overall formation history\nhas remained unknown up to now. Here we report the first detailed star\nformation history of this region. The bulk of its stars formed at least eight\nbillion years ago. This initial activity was followed by a long period of\nquiescence that was ended by an outstanding event about 1 Gyr ago, during which\nroughly 5% of its mass formed in a time window $\\sim$100 Myr, in what may\narguably have been one of the most energetic events in the history of the Milky\nWay. Star formation continued subsequently on a lower level, creating a few\npercent of the stellar mass in the past $\\sim$500 Myr, with an increased rate\nup to $\\sim$30 Myr ago. Our findings contradict the previously accepted\nparadigm of quasi-continuous star formation at the centre of the Milky Way. The\nlong quiescent phase agrees with the overall quiescent history of the Milky Way\nand suggests that our Galaxy's bar may not have existed until recently, or that\ngas transport through the bar was extremely inefficient during a long stretch\nof the Milky Way's life, and that the central black hole may have acquired most\nof its mass already in the early days of the Milky Way.", "positive": "Brightest Cluster Galaxies Are Statistically Special From $z=0.3$ to\n $z=1$: We study Brightest Cluster Galaxies (BCGs) in $\\sim5000$ galaxy clusters from\nthe Hyper Suprime-Cam (HSC) Subaru Strategic Program. The sample is selected\nover an area of 830 $\\textrm{deg}^2$ and is uniformly distributed in redshift\nover the range $z=0.3-1.0$. The clusters have stellar masses in the range\n$10^{11.8} - 10^{12.9} M_{\\odot}$. We compare the stellar mass of the BCGs in\neach cluster to what we would expect if their masses were drawn from the mass\ndistribution of the other member galaxies of the clusters. The BCGs are found\nto be \"special\", in the sense that they are not consistent with being a\nstatistical extreme of the mass distribution of other cluster galaxies. This\nresult is robust over the full range of cluster stellar masses and redshifts in\nthe sample, indicating that BCGs are special up to a redshift of $z=1.0$.\nHowever, BCGs with a large separation from the center of the cluster are found\nto be consistent with being statistical extremes of the cluster member mass\ndistribution. We discuss the implications of these findings for BCG formation\nscenarios." }, { "anchor": "ALMA Lensing Cluster Survey: an ALMA galaxy signposting a MUSE galaxy\n group at z=4.3 behind 'El Gordo': We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy\ngroup at z=4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El\nGordo) at z=0.87, associated with a 1.2 mm source which is at a 2.07+/-0.88 kpc\nprojected distance from one of the group galaxies. Three images of the whole\nsystem appear in the image plane. The 1.2 mm source has been detected within\nthe Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey\n(ALCS). As this ALMA source is undetected at wavelengths lambda < 2 microns,\nits redshift cannot be independently determined, however, the three lensing\ncomponents indicate that it belongs to the same galaxy group at z=4.32. The\nfour members of the MUSE galaxy group have low to intermediate stellar masses\n(~ 10^7-10^{10} Msun) and star formation rates (SFRs) of 0.4-24 Msun/yr,\nresulting in high specific SFRs (sSFRs) for two of them, which suggest that\nthese galaxies are growing fast (with stellar-mass doubling times of only ~\n2x10^7 years). This high incidence of starburst galaxies is likely a\nconsequence of interactions within the galaxy group, which is compact and has\nhigh velocity dispersion. Based on the magnification-corrected sub-/millimetre\ncontinuum flux density and estimated stellar mass, we infer that the ALMA\nsource is classified as an ordinary ultra-luminous infrared galaxy (with\nassociated dust-obscured SFR~200-300 Msun/yr) and lies on the star-formation\nmain sequence. This reported case of an ALMA/MUSE group association suggests\nthat some presumably isolated ALMA sources are in fact signposts of richer\nstar-forming environments at high redshifts.", "positive": "Searching for the connection between ionizing-photon escape and the\n surface density of star formation at z~3: The connection between the escape fraction of ionizing photons ($f_{\\rm\nesc}$) and star-formation rate surface density ($\\Sigma_{\\rm SFR}$) is a key\ninput for reionization models, but remains untested at high redshift. We\nanalyse 35 z~3 galaxies from the Keck Lyman Continuum Survey (KLCS) covered by\ndeep, rest far-UV spectra of the Lyman continuum (LyC) and high-resolution HST\nV$_{606}$ imaging, enabling estimates of both $f_{\\rm esc}$ and rest-UV sizes.\nUsing S\\'ersic profile fits to HST images and spectral-energy distribution fits\nto multi-band photometry, we measure effective sizes and star-formation rates\nfor the galaxies in our sample, and separate the sample into two bins of\n$\\Sigma_{\\rm SFR}$. Based on composite spectra, we estimate <$f_{\\rm esc}$> for\nboth $\\Sigma_{\\rm SFR}$ subsamples, finding no significant difference in\n<$f_{\\rm esc}$> between the two. To test the representativeness of the KLCS HST\nsample and the robustness of this result, we attempt to recover the\nwell-established correlation between $f_{\\rm esc}$ and Ly$\\alpha$ equivalent\nwidth. This correlation is not significant within the KLCS HST sample,\nindicating that the sample is not sufficient for correlating $f_{\\rm esc}$ and\ngalaxy properties such as $\\Sigma_{\\rm SFR}$. We perform stacking simulations\nusing the KLCS parent sample to determine the optimal sample size for robust\nprobes of the $f_{\\rm esc}$-$\\Sigma_{\\rm SFR}$ connection to inform future HST\nLyC observing programs. For a program with a selection independent of ionizing\nproperties, >= 90 objects are required; for one preferentially observing\nstrongly-leaking LyC sources, >= 58 objects are required. More generally,\nmeasuring the connection between $f_{\\rm esc}$ and $\\Sigma_{\\rm SFR}$ requires\na larger, representative sample spanning a wide dynamic range in galaxies\nproperties such as $\\Sigma_{\\rm SFR}$." }, { "anchor": "The Way to Quench: Galaxy evolution in Abell 2142: We show how the star formation activity of galaxies is progressively\ninhibited from the outer region to the center of the massive cluster A2142.\nFrom an extended spectroscopic redshift survey of 2239 galaxies covering a\ncircular area of radius $\\sim 11$~Mpc from the cluster center, we extract a\nsample of 333 galaxies with known stellar mass, star formation rate, and\nspectral index $D_n4000$. We use the Blooming Tree algorithm to identify the\nsubstructures of the cluster and separate the galaxy sample into substructure\ngalaxies, halo galaxies and outskirt galaxies. The substructure and halo\ngalaxies are cluster members, whereas the outskirt galaxies are only weakly\ngravitationally bound to the cluster. For the cluster members, the star\nformation rate per stellar mass decreases with decreasing distance $R$ from the\ncluster center. Similarly, the spectral index $D_n4000$ increases with $R$,\nindicating an increasingly average age of the stellar population in galaxies\ncloser to the cluster center. In addition, star formation in substructure\ngalaxies is generally more active than in halo galaxies and less active than in\noutskirt galaxies, proving that substructures tend to slow down the transition\nbetween field galaxies and cluster galaxies. We finally show that most actively\nstar forming galaxies are within the cluster infall region, whereas most\ngalaxies in the central region are quiescent.", "positive": "Low-mass and High-mass Supermassive Blackholes In Radio-Loud AGNs Are\n Spun-up in Different Evolution Paths: How Supermassive Blackholes (SMBHs) are spun-up is a key issue of modern\nastrophysics. As an extension of the study in Wang et al. (2016), we here\naddress the issue by comparing the host galaxy properties of nearby ($z<0.05$)\nradio-selected Seyfert 2 galaxies. With the two-dimensional bulge+disk\ndecompositions for the SDSS $r$-band images, we identify a dichotomy on various\nhost galaxy properties for the radio-powerful SMBHs. By assuming the radio\nemission from the jet reflects a high SMBH spin, which stems from the\nwell-known BZ mechanism of jet production, high-mass SMBHs (i.e.,\n$M_{\\mathrm{BH}}>10^{7.9}M_\\odot$) have a preference for being spun-up in\nclassical bulges, and low-mass SMBHs (i.e., $M_{\\mathrm{BH}}=10^{6-7}M_\\odot$)\nin pseudo-bulges. This dichotomy suggests and confirms that high-mass and\nlow-mass SMBHs are spun-up in different ways, i.e., a major \"dry\" merger and a\nsecular evolution." }, { "anchor": "Galactic Archaeology with CoRoT and APOGEE: Creating mock observations\n from a chemodynamical model: In a companion paper, we have presented the combined\nasteroseismic-spectroscopic dataset obtained from CoRoT lightcurves and APOGEE\ninfra-red spectra for 678 solar-like oscillating red giants in two fields of\nthe Galactic disc (CoRoGEE). We have measured chemical abundance patterns,\ndistances, and ages of these field stars which are spread over a large radial\nrange of the Milky Way's disc. Here we show how to simulate this dataset using\na chemodynamical Galaxy model. We also demonstrate how the observation\nprocedure influences the accuracy of our estimated ages.", "positive": "Exploring metallicity-dependent rates of Type Ia supernovae and their\n impact on galaxy formation: Type Ia supernovae play a critical role in stellar feedback and elemental\nenrichment in galaxies. Recent transient surveys like the All-Sky Automated\nSurvey for Supernova (ASAS-SN) and the Dark Energy Survey (DES) find that the\nspecific Ia rate at z ~ 0 may be ~ 15-50 times higher in lower-mass galaxies\nthan at Milky Way-mass. Independently, Milky Way observations show that the\nclose-binary fraction of solar-type stars is higher at lower metallicity.\nMotivated by these observations, we use the FIRE-2 cosmological zoom-in\nsimulations to explore the impact of varying Ia rate models, including\nmetallicity dependence, on galaxies across a range of stellar masses: 10^7 Msun\n- 10^{11} Msun. First, we benchmark our simulated star-formation histories\n(SFHs) against observations. We show that assumed SFHs and stellar mass\nfunctions play a major role in determining the degree of tension between\nobservations and metallicity-independent Ia rate models, and potentially cause\nASAS-SN and DES observations to be much more consistent with each other than\nmight naively appear. Models in which the Ia rate increases with decreasing\nmetallicity (as ~ Z^{-0.5} to Z^{-1}) provide significantly better agreement\nwith observations. Encouragingly, these increases in Ia rate (> 10 times in\nlow-mass galaxies) do not significantly impact galaxy stellar masses and\nmorphologies: effective radii, axis ratios, and v/sigma remain largely\nunaffected except for our most extreme rate models. We explore implications for\nboth [Fe/H] and [alpha/Fe] enrichment: metallicity-dependent Ia rate models can\nimprove agreement with observed stellar mass-metallicity relations in low-mass\ngalaxies. Our results demonstrate that a wide range of metallicity-dependent Ia\nmodels are viable for galaxy formation and motivate future work in this area." }, { "anchor": "Identification of a transition from stochastic to secular star formation\n around $z=9$ with JWST: Star formation histories (SFH) of early (6$9$, 87% of massive galaxies,\n($\\log(M_\\ast/M_\\odot)\\gtrsim$9), have SFR gradients consistent with a\nstochastic star-formation activity during the last 100 Myr, while this fraction\ndrops to 15% at $z<7$. On the other hand, we see an increasing fraction of\ngalaxies with a star-formation activity following a common stream on the\nSFR-$M_\\ast$ plane with cosmic time, indicating that a secular mode of\nstar-formation is emerging. We place our results in the context of the observed\nexcess of UV emission as probed by the UV luminosity function at $z\\gtrsim10$,\nby estimating $\\sigma_{UV}$, the dispersion of the UV absolute magnitude\ndistribution, to be of the order of 1.2mag and compare it with predictions from\nthe literature. In conclusion, we find a transition of star-formation mode\nhappening around $z\\sim9$: Galaxies with stochastic SFHs dominates at\n$z\\gtrsim9$, although this level of stochasticity is too low to reach those\ninvoked by recent models to reproduce the observed UV luminosity function.", "positive": "Determining the Orientation Parameters of the ICRS/UCAC2 System Using\n the Kharkov Catalog of Absolute Stellar Proper Motions: The absolute proper motions of about 275 million stars from the Kharkov XPM\ncatalog have been obtained by comparing their positions in the 2MASS and\nUSNO--A2.0 catalogs with an epoch difference of about 45 yr for\nnorthern-hemisphere stars and about 17 yr for southern-hemisphere stars. The\nzero point of the system of absolute proper motions has been determined using\n1.45 million galaxies. The equatorial components of the residual rotation\nvector of the ICRS/UCAC2 coordinate system relative to the system of\nextragalactic sources have been determined by comparing the XPM and UCAC2\nstellar proper motions: \\omega_{x,y,z}=(-0.06,0.17,-0.84)+/-(0.15,0.14,0.14)\nmas yr^{-1}. These parameters have been calculated using about 1 million\nfaintest UCAC2 stars with magnitudes R_{UCAC2}>16^m and J>14^m.7,for which the\ncolor and magnitude equation effects are negligible." }, { "anchor": "The Extreme Microlensing Event OGLE-2007-BLG-224: Terrestrial Parallax\n Observation of a Thick-Disk Brown Dwarf: Parallax is the most fundamental technique to measure distances to\nastronomical objects. Although terrestrial parallax was pioneered over 2000\nyears ago by Hipparchus (ca. 140 BCE) to measure the distance to the Moon, the\nbaseline of the Earth is so small that terrestrial parallax can generally only\nbe applied to objects in the Solar System. However, there exists a class of\nextreme gravitational microlensing events in which the effects of terrestrial\nparallax can be readily detected and so permit the measurement of the distance,\nmass, and transverse velocity of the lens. Here we report observations of the\nfirst such extreme microlensing event OGLE-2007-BLG-224, from which we infer\nthat the lens is a brown dwarf of mass M=0.056 +- 0.004 Msun, with a distance\nof 525 +- 40 pc and a transverse velocity of 113 +- 21 km/s. The velocity\nplaces the lens in the thick disk, making this the lowest-mass thick-disk brown\ndwarf detected so far. Follow-up observations may allow one to observe the\nlight from the brown dwarf itself, thus serving as an important constraint for\nevolutionary models of these objects and potentially opening a new window on\nsub-stellar objects. The low a priori probability of detecting a thick-disk\nbrown dwarf in this event, when combined with additional evidence from other\nobservations, suggests that old substellar objects may be more common than\npreviously assumed.", "positive": "Yule-Simpson's paradox in Galactic Archaeology: Simpson's paradox, or Yule-Simpson effect, arises when a trend appears in\ndifferent subsets of data but disappears or reverses when these subsets are\ncombined. We describe here seven cases of this phenomenon for chemo-kinematical\nrelations believed to constrain the Milky Way disk formation and evolution. We\nshow that interpreting trends in relations, such as the radial and vertical\nchemical abundance gradients, the age-metallicity relation, and the\nmetallicity-rotational velocity relation (MVR), can lead to conflicting\nconclusions about the Galaxy past if analyses marginalize over stellar age\nand/or birth radius. It is demonstrated that the MVR in RAVE giants is\nconsistent with being always strongly negative, when narrow bins of [Mg/Fe] are\nconsidered. This is directly related to the negative radial metallicity\ngradients of stars grouped by common age (mono-age populations) due to the\ninside out disk formation. The effect of the asymmetric drift can then give\nrise to a positive MVR trend in high-[alpha/Fe] stars, with a slope dependent\non a given survey's selection function and observational uncertainties. We also\nstudy the variation of lithium abundance, A(Li), with [Fe/H] of AMBRE:HARPS\ndwarfs. A strong reversal in the positive A(Li)-[Fe/H] trend of the total\nsample is found for mono-age populations, flattening for younger groups of\nstars. Dissecting by birth radius shows strengthening in the positive\nA(Li)-[Fe/H] trend, shifting to higher [Fe/H] with decreasing birth radius;\nthese observational results suggest new constraints on chemical evolution\nmodels. This work highlights the necessity for precise age estimates for large\nstellar samples covering wide spatial regions." }, { "anchor": "The Globular Cluster System of NGC 5128: Ages, Metallicities,\n Kinematics, and Structural Parameters: We review our recent studies of the globular cluster system of NGC 5128.\nFirst, we have obtained low-resolution, high signal-to-noise spectroscopy of 72\nglobular clusters using Gemini-S/GMOS to obtain the ages, metallicities, and\nthe level of alpha enrichment of the metal-poor and metal-rich globular cluster\nsubpopulations. Second, we have explored the rotational signature and velocity\ndispersion of the galaxy's halo using over 560 globular clusters with radial\nvelocity measurements. We have also compared the dependence of these properties\non galactocentric distance and globular cluster age and metallicity. Using\nglobular clusters as tracer objects, we have analyzed the mass, and M/L ratio\nof NGC 5128. Last, we have measured the structural parameters, such as\nhalf-light radii, of over 570 globular clusters from a superb 1.2 square degree\nMagellan/IMACS image. We will present the findings of these studies and discuss\nthe connection to the formation and evolution of NGC 5128.", "positive": "Extended radio emission in the galaxy cluster MS 0735.6+7421 detected\n with the Karl G. Jansky Very Large Array: MS 0735.6+7421 ($z = 0.216$) is a massive cool core galaxy cluster hosting\none of the most powerful active galactic nuclei (AGN) outbursts known. The\nradio jets of the AGN have carved out an unusually large pair of X-ray\ncavities, each reaching a diameter of $200$ kpc. This makes MS 0735.6+7421 a\nunique case to investigate active galactic nuclei feedback processes, as well\nas other cluster astrophysics at radio wavelengths. We present new\nlow-radio-frequency observations of MS 0735.6+7421 taken with the Karl G.\nJansky Very Large Array (VLA): 5 hours of P-band ($224-480$ MHz) and 5 hours of\nL-band ($1-2$ GHz) observations, both in C configuration. Our VLA P-band\n($224-480$ MHz) observations reveal the presence of a new diffuse radio\ncomponent reaching a scale of $\\sim$ $900$ kpc in the direction of the jets and\nof $\\sim$ $500$ kpc in the direction perpendicular to the jets. This component\nis centered on the cluster core and has a radio power scaled at $1.4$ GHz of\n$P_{1.4\\text{ GHz}} = (4\\pm2)\\times 10^{24}$ WHz$^{-1}$. Its properties are\nconsistent with those expected from a radio mini-halo as seen in other massive\ncool core clusters, although it may also be associated with radio plasma that\nhas diffused out of the X-ray cavities. Observations at higher spatial\nresolution are needed to fully characterize the properties and nature of this\ncomponent. We also suggest that if radio mini-halos originate from jetted\nactivity, we may be witnessing the early stages of this process." }, { "anchor": "Mapping low frequency carbon radio recombination lines towards\n Cassiopeia A at 340, 148, 54 and 43 MHz: Quantitative understanding of the interstellar medium requires knowledge of\nits physical conditions. Low frequency carbon radio recombination lines (CRRLs)\ntrace cold interstellar gas, and can be used to determine its physical\nconditions (e.g., electron temperature and density). In this work we present\nspatially resolved observations of the low frequency ($\\leq390$ MHz) CRRLs\ncentered around C$268\\alpha$, C$357\\alpha$, C$494\\alpha$ and C$539\\alpha$\ntowards Cassiopeia A on scales of $\\leq1.2$ pc. We compare the spatial\ndistribution of CRRLs with other ISM tracers. This comparison reveals a spatial\noffset between the peak of the CRRLs and other tracers, which is very\ncharacteristic for photodissociation regions and that we take as evidence for\nCRRLs being preferentially detected from the surfaces of molecular clouds.\nUsing the CRRLs we constrain the gas electron temperature and density. These\nconstraints on the gas conditions suggest variations of less than a factor of\ntwo in pressure over $\\sim1$ pc scales, and an average hydrogen density of\n$200$-$470$ cm$^{-3}$. From the electron temperature and density maps we also\nconstrain the ionized carbon emission measure, column density and path length.\nBased on these, the hydrogen column density is larger than $10^{22}$ cm$^{-2}$,\nwith a peak of $\\sim4\\times10^{22}$ cm$^{-2}$ towards the South of Cassiopeia\nA. Towards the southern peak the line of sight length is $\\sim40$ pc over a\n$\\sim2$ pc wide structure, which implies that the gas is a thin surface layer\non a large (molecular) cloud that is only partially intersected by Cassiopeia\nA. These observations highlight the utility of CRRLs as tracers of low density\nextended HI and CO-dark gas halo's around molecular clouds.", "positive": "Difference in the spatial distribution between H_2O and CO_2 ices in M82\n found with AKARI: With AKARI, we obtain the spatially-resolved near-infrared (2.5 - 5.0 um)\nspectra for the nearby starburst galaxy M82. These spectra clearly show the\nabsorption features due to interstellar ices. Based on the spectra, we created\nthe column density maps of H_2O and CO_2 ices. As a result, we find that the\nspatial distribution of H_2O ice is significantly different from that of CO_2\nice; H_2O ice is widely distributed, while CO_2 ice is concentrated near the\ngalactic center. Our result for the first time reveals variations in CO_2/H_2O\nice abundance ratio on a galactic scale, suggesting that the ice-forming\ninterstellar environment changes within a galaxy. We discuss the cause of the\nspatial variations in the ice abundance ratio, utilizing spectral information\non the hydrogen recombination Br{\\alpha} and Br{\\beta} lines and the polycyclic\naromatic hydrocarbon 3.3 um emission appearing in the AKARI near-infrared\nspectra." }, { "anchor": "Kinematics of the diffuse intragroup and intracluster light in groups\n and clusters of galaxies in the Local Universe within 100 Mpc distance: Nearly all intragroup (IGL) and intracluster light (ICL) comes from stars\nthat are not bound to any single galaxy but were formed in galaxies and later\nunbound from them. In this review we focus on the physical properties - phase\nspace properties, metallicity and age distribution - of the ICL and IGL\ncomponents of the groups and clusters in the local universe, within 100 Mpc\ndistance. Kinematic information on these very low surface brightness structures\nmostly comes from discrete tracers such as planetary nebulae and globular\nclusters, showing highly unrelaxed velocity distributions. Cosmological\nhydrodynamical simulations provide key predictions for the dynamical state of\nIGL and ICL and find that most IC stars are dissolved from galaxies that\nsubsequently merge with the central galaxy. The increase of the measured\nvelocity dispersion with radius in the outer halos of bright galaxies is a\nphysical feature that makes it possible to identify IGL and ICL components. In\nthe local groups and clusters, IGL and ICL are located in the dense regions of\nthese structures. Their light fractions relative to the total luminosity of the\nsatellite galaxies in a given group or cluster are between a few to ten\npercent, significantly lower than the average values in more evolved, more\ndistant clusters. IGL and ICL in the Leo I and M49 groups, and the Virgo\ncluster core around M87, has been found to arise from mostly old (>~10 Gyr)\nmetal-poor ([Fe/H]<-1.0) stars of low-mass progenitor galaxies. New imaging\nfacilities such as LSST, Euclid, and the `big eyes' on the sky - ELT and JWST\nwith their advanced instrumentation-promise to greatly increase our knowledge\nof the progenitors of the IGL and ICL stars, their ages, metal content, masses\nand evolution, thereby increasing our understanding of this enigmatic\ncomponent.", "positive": "Large Variety of New Pulsating Stars in the OGLE-III Galactic Disk\n Fields: We present the results of a search for pulsating stars in the 7.12 deg^2\nOGLE-III Galactic disk area in the direction tangent to the Centaurus Arm. We\nreport the identification of 20 Classical Cepheids, 45 RR Lyr type stars, 31\nLong-Period Variables, such as Miras and Semi-Regular Variables, one pulsating\nwhite dwarf, and 58 very likely delta Sct type stars. Based on asteroseismic\nmodels constructed for one quadruple-mode and six triple-mode delta Sct type\npulsators, we estimated masses, metallicities, ages, and distance moduli to\nthese objects. The modeled stars have masses in the range 0.9-2.5 M_sun and are\nlocated at distances between 2.5 kpc and 6.2 kpc. Two triple-mode and one\ndouble-mode pulsators seem to be Population II stars of the SX Phe type,\nprobably from the Galactic halo. Our sample also includes candidates for Type\nII Cepheids and unclassified short-period (P<0.23 d) multi-mode stars which\ncould be either delta Sct or beta Cep type stars. One of the detected variables\nis a very likely delta Sct star with an exceptionally high peak-to-peak I-band\namplitude of 0.35 mag at the very short period of 0.0196 d. All reported\npulsating variables but one object are new discoveries. They are included in\nthe OGLE-III Catalog of Variable Stars. Finally, we introduce the on-going\nOGLE-IV Galactic Disk Survey, which covers more than half of the Galactic\nplane. For the purposes of future works on the spiral structure and star\nformation history of the Milky Way, we have already compiled a list of known\nGalactic Classical Cepheids." }, { "anchor": "Characterization of Optical Light Curves of Extreme Variability Quasars\n Over a ~16-yr Baseline: We study the optical light curves - primarily probing the variable emission\nfrom the accretion disk - of ~ 900 extreme variability quasars (EVQs, with\nmaximum flux variations more than 1 mag) over an observed-frame baseline of ~\n16 years using public data from the SDSS Stripe 82, PanSTARRS-1 and the Dark\nEnergy Survey. We classify the multi-year long-term light curves of EVQs into\nthree categories roughly in the order of decreasing smoothness: monotonic\ndecreasing or increasing (3.7%), single broad peak and dip (56.8%), and more\ncomplex patterns (39.5%). The rareness of monotonic cases suggests that the\nmajor mechanisms driving the extreme optical variability do not operate over\ntimescales much longer than a few years. Simulated light curves with a damped\nrandom walk model generally under-predict the first two categories with\nsmoother long-term trends. Despite the different long-term behaviors of these\nEVQs, there is little dependence of the long-term trend on the physical\nproperties of quasars, such as their luminosity, BH mass, and Eddington ratio.\nThe large dynamic range of optical flux variability over multi-year timescales\nof these EVQs allows us to explore the ensemble correlation between the\nshort-term (< 6 months) variability and the seasonal-average flux across the\ndecade-long baseline (the rms-mean flux relation). We find that unlike the\nresults for X-ray variability studies, the linear short-term flux variations do\nnot scale with the seasonal-average flux, indicating different mechanisms that\ndrive the short-term flickering and long-term extreme variability of accretion\ndisk emission. Finally, we present a sample of 16 EVQs, where the approximately\nbell-shaped large amplitude variation in the light curve can be reasonably well\nfit by a simple microlensing model.", "positive": "Starburst galaxies: The rate of star formation varies between galaxy types and evolves with\nredshift. Most stars in the universe have formed in episodes of an\nexceptionally high star-forming activity, commonly called a starburst. We here\nsummarize basic definitions and general properties of starbursts, together with\ntheir observational signatures.We overviewthe main types of starburst galaxies\nboth in the local universe and at high redshift, where they were much more\ncommon. We specify similarities and differences between the local and distant\nsamples and specify the possible evolutionary links. We describe the role of\nstarburst galaxies in the era of cosmic reionization, relying on the most\nrecent observational results." }, { "anchor": "An Origin for Multi-Phase Gas in Galactic Winds and Halos: The physical origin of high velocity cool gas seen in galactic winds remains\nunknown. Following Wang (1995), we argue that radiative cooling in initially\nhot thermally-driven outflows can produce fast neutral atomic and photoionized\ncool gas. The inevitability of adiabatic cooling from the flow's initial\n10^7-10^8K temperature and the shape of the cooling function for T<10^7K imply\nthat outflows with hot gas mass-loss rate relative to star formation rate of\nbeta=Mdot_hot/Mdot_star > 0.5 cool radiatively on scales ranging from the size\nof the energy injection region to tens of kpc. We highlight the beta and star\nformation rate surface density dependence of the column density, emission\nmeasure, radiative efficiency, and velocity. At r_cool, the gas produces X-ray\nand then UV/optical line emission with a total power bounded by 10^{-2} L_star\nif the flow is powered by steady-state star formation with luminosity L_star.\nThe wind is thermally unstable at r_cool, potentially leading to a multi-phase\nmedium. Cooled winds decelerate significantly in the extended gravitational\npotential of galaxies. The cool gas precipitated from hot outflows may explain\nits prevalence in galactic halos. We forward a picture of winds whereby cool\nclouds are initially accelerated by the ram pressure of the hot flow, but are\nrapidly shredded by hydrodynamical instabilities, thereby increasing beta,\nseeding radiative and thermal instability, and cool gas rebirth. If the cooled\nwind shocks as it sweeps up the circumgalactic medium, its cooling time is\nshort, thus depositing cool gas far out into the halo. Finally, conduction can\ndominate energy transport in low-beta hot winds, leading to flatter temperature\nprofiles than otherwise expected, potentially consistent with X-ray\nobservations of some starbursts.", "positive": "Tests of AGN Feedback Kernels in Simulated Galaxy Clusters: In cool-core galaxy clusters with central cooling times much shorter than a\nHubble time, condensation of the ambient central gas is regulated by a heating\nmechanism, probably an active galactic nucleus (AGN). Previous analytical work\nhas suggested that certain radial distributions of heat input may result in\nconvergence to a quasi-steady global state that does not substantively change\non the timescale for radiative cooling, even if the heating and cooling are not\nlocally in balance. To test this hypothesis, we simulate idealized galaxy\ncluster halos using the \\ENZO code with an idealized, spherically symmetric\nheat-input kernel intended to emulate. Thermal energy is distributed with\nradius according to a range of kernels, in which total heating is updated to\nmatch total cooling every $10 ~\\text{Myr}$. Some heating kernels can maintain\nquasi-steady global configurations, but no kernel we tested produces a\nquasi-steady state with central entropy as low as those observed in cool-core\nclusters. The general behavior of the simulations depends on the proportion of\nheating in the inner $10 ~\\text{kpc}$, with low central heating leading to\ncentral cooling catastrophes, high central heating creating a central\nconvective zone with an inverted entropy gradient, and intermediate central\nheating resulting in a flat central entropy profile that exceeds observations.\nThe timescale on which our simulated halos fall into an unsteady multiphase\nstate is proportional to the square of the cooling time of the lowest entropy\ngas, allowing more centrally concentrated heating to maintain a longer lasting\nsteady state." }, { "anchor": "Direct determination of oxygen abundances in line emitting star-forming\n galaxies at intermediate redshift: We present a sample of 22 blue ($(B-V)_{AB}<0.45$), luminous\n($M_{B,AB}<-18.9$), metal-poor galaxies in the $0.69 100 m$\\AA$ C IV\nabsorption detected at low z. Comparing the C IV covering fraction with\nhydrodynamical simulations, we find that an energy-driven wind model is\nconsistent with the observations whereas a wind model of constant velocity\nfails to reproduce the CGM or the galaxy properties.", "positive": "Setting the Stage for Cosmic Chronometers. II. Impact of Stellar\n Population Synthesis Models Systematics and Full Covariance Matrix: The evolution of differential ages of passive galaxies at different redshifts\n(cosmic chronometers) has been proved to be a method potentially able to\nconstrain the Hubble parameter in a cosmology-independent way, but the\nsystematic uncertainties must be carefully evaluated. In this paper, we compute\nthe contribution to the full covariance matrix of systematic uncertainties due\nto the choice of initial mass function, stellar library, and metallicity,\nexploring a variety of stellar population synthesis models. Through simulations\nin the redshift range 0 0.012$.", "positive": "First Gaia Local Group Dynamics: Magellanic Clouds Proper Motion and\n Rotation: We use the Gaia data release 1 (DR1) to study the proper motion (PM) fields\nof the Large and Small Magellanic Clouds (LMC, SMC). This uses the Tycho-Gaia\nAstrometric Solution (TGAS) PMs for 29 Hipparcos stars in the LMC and 8 in the\nSMC. The LMC PM in the West and North directions is inferred to be\n$(\\mu_W,\\mu_N) = (-1.872 \\pm 0.045, 0.224 \\pm 0.054)$ mas/yr, and the SMC PM\n$(\\mu_W,\\mu_N) = (-0.874 \\pm 0.066, -1.229 \\pm 0.047)$ mas/yr. These results\nhave similar accuracy and agree to within the uncertainties with existing\nHubble Space Telescope (HST) PM measurements. Since TGAS uses different methods\nwith different systematics, this provides an external validation of both data\nsets and their underlying approaches. Residual DR1 systematics may affect the\nTGAS results, but the HST agreement implies this must be below the random\nerrors. Also in agreement with prior HST studies, the TGAS LMC PM field clearly\nshows the clockwise rotation of the disk, even though it takes the LMC disk in\nexcess of $10^8$ years to complete one revolution. The implied rotation curve\namplitude for young LMC stars is consistent with that inferred from\nline-of-sight (LOS) velocity measurements. Comparison of the PM and LOS\nrotation curves implies a kinematic LMC distance modulus $m-M = 18.54 \\pm\n0.39$, consistent but not yet competitive with photometric methods. These first\nresults from Gaia on the topic of Local Group dynamics provide an indication of\nhow its future data releases will revolutionize this field." }, { "anchor": "The Role of Star-Formation and AGN in Dust Heating of z=0.3-2.8 Galaxies\n - II. Informing IR AGN fraction estimates through simulations: A key question in extragalactic studies is the determination of the relative\nroles of stars and AGN in powering dusty galaxies at $z\\sim$1-3 where the bulk\nof star-formation and AGN activity took place. In Paper I, we present a sample\nof $336$ 24$\\mu$m-selected (Ultra)Luminous Infrared Galaxies, (U)LIRGs, at $z\n\\sim 0.3$-$2.8$, where we focus on determining the AGN contribution to the IR\nluminosity. Here, we use hydrodynamic simulations with dust radiative transfer\nof isolated and merging galaxies, to investigate how well the simulations\nreproduce our empirical IR AGN fraction estimates and determine how IR AGN\nfractions relate to the UV-mm AGN fraction. We find that: 1) IR AGN fraction\nestimates based on simulations are in qualitative agreement with the empirical\nvalues when host reprocessing of the AGN light is considered; 2) for\nstar-forming galaxy-AGN composites our empirical methods may be underestimating\nthe role of AGN, as our simulations imply $>$50% AGN fractions, $\\sim$3$\\times$\nhigher than previous estimates; 3) 6% of our empirically classified \"SFG\" have\nAGN fractions $\\gtrsim$50%. While this is a small percentage of SFGs, if\nconfirmed, would imply the true number density of AGN may be underestimated; 4)\nthis comparison depends on the adopted AGN template -- those that neglect the\ncontribution of warm dust lower the empirical fractions by up to 2$\\times$; and\n5) the IR AGN fraction is only a good proxy for the intrinsic UV-mm AGN\nfraction when the extinction is high ($A_V\\gtrsim 1$ or up to and including\ncoalescence in a merger).", "positive": "The physical origins and dominant emission mechanisms of Lyman-alpha\n halos: results from the TNG50 simulation in comparison to MUSE observations: Extended Lyman-alpha emission is now commonly detected around high redshift\ngalaxies through stacking and even on individual basis. Despite recent\nobservational advances, the physical origin of these Lyman-alpha halos (LAHs),\nas well as their relationships to galaxies, quasars, circumgalactic gas, and\nother environmental factors remains unclear. We present results from our new\nLyman-alpha full radiative transfer code voroILTIS which runs directly on the\nunstructured Voronoi tessellation of cosmological hydrodynamical simulations.\nWe make use of the TNG50 simulation and simulate LAHs from redshift $z=2$ to\n$z=5$, focusing on star-forming galaxies with $8.0 <\n\\log_{10}{(M_\\star/\\rm{M}_\\odot)} < 10.5$. While TNG50 does not directly follow\nionizing radiation, it includes an on-the-fly treatment for active galactic\nnuclei and ultraviolet background radiation with self-shielding, which are\nimportant processes impacting the cooling and ionization of the gas. Based on\nthis model, we present the predictions for the stacked radial surface\nbrightness profiles of Ly$\\alpha$ as a function of galaxy mass and redshift.\nComparison with data from the MUSE UDF at $z>3$ reveals a promising level of\nagreement. We measure the correlations of LAH size and central brightness with\ngalaxy properties, finding that at the masses of $8.5 \\leq \\log_{10}\n\\left(M_\\star/\\rm{M}_\\odot\\right) \\leq 9.5$, physical LAH sizes roughly double\nfrom $z=2$ to $z=5$. Finally, we decompose the profiles into contributions from\ndiffuse emission and scattered photons from star-forming regions. In our\nsimulations, we find rescattered photons from star-forming regions to be the\nmajor source in observed LAHs. Unexpectedly, we find that the flattening of LAH\nprofiles at large radii becomes dominated by photons originating from other\nnearby halos rather than diffuse emission itself." }, { "anchor": "APOGEE DR16: a multi-zone chemical evolution model for the Galactic disc\n based on MCMC methods: The analysis of the APOGEE DR16 data suggests the existence of a clear\ndistinction between two sequences of disc stars at different Galactocentric\ndistances in the [$\\alpha$/Fe] vs. [Fe/H] abundance ratio space: the so-called\nhigh-$\\alpha$ sequence, classically associated to an old population of stars in\nthe thick disc, and the low-$\\alpha$ sequence, which mostly comprises\nrelatively young stars in the thin disc. We perform a Bayesian analysis based\non a Markov Chain Monte Carlo method to constrain a multi-zone two-infall\nchemical evolution model designed for regions at different Galactocentric\ndistances using measured chemical abundances from the APOGEE DR16 sample. An\ninside-out formation of the Galaxy disc naturally emerges from the best fit of\nour two-infall chemical-evolution model to APOGEE-DR16: inner Galactic regions\nare assembled on shorter time-scales compared to the external ones. In the\nouter disc (with radii $R>6$ kpc), the chemical dilution due to a late\naccretion event of gas with primordial chemical composition is the main driver\nof the [Mg/Fe] vs. [Fe/H] abundance pattern in the low-$\\alpha$ sequence. In\nthe inner disc, in the framework of the two-infall model, we confirm the\npresence of an enriched gas infall in the low-$\\alpha$ phase as suggested by\nchemo-dynamical models. Our Bayesian analysis of the recent APOGEE DR16 data\nsuggests a significant delay time, ranging from $\\sim$3.0 to 4.7 Gyr, between\nthe first and second gas infall events for all the analyzed Galactocentric\nregions. Our results propose a clear interpretation of the [Mg/Fe] vs. [Fe/H]\nrelations along the Galactic discs. The signatures of a delayed gas-rich merger\nwhich gives rise to a hiatus in the star formation history of the Galaxy are\nimpressed in the [Mg/Fe] vs. [Fe/H] relation, determining how the low-$\\alpha$\nstars are distributed in the abundance space at different Galactocentric\ndistances.", "positive": "Gaia Data Release 2: Mapping the Milky Way disc kinematics: To illustrate the potential of GDR2, we provide a first look at the\nkinematics of the Milky Way disc, within a radius of several kiloparsecs around\nthe Sun. We benefit for the first time from a sample of 6.4 million F-G-K stars\nwith full 6D phase-space coordinates, precise parallaxes, and precise Galactic\ncylindrical velocities . From this sample, we extracted a sub-sample of 3.2\nmillion giant stars to map the velocity field of the Galactic disc from\n$\\sim$5~kpc to $\\sim$13~kpc from the Galactic centre and up to 2~kpc above and\nbelow the plane. We also study the distribution of 0.3 million solar\nneighbourhood stars ($r < 200$~pc), with median velocity uncertainties of\n0.4~km/s, in velocity space and use the full sample to examine how the\nover-densities evolve in more distant regions. GDR2 allows us to draw 3D maps\nof the Galactocentric median velocities and velocity dispersions with\nunprecedented accuracy, precision, and spatial resolution. The maps show the\ncomplexity and richness of the velocity field of the galactic disc. We observe\nstreaming motions in all the components of the velocities as well as patterns\nin the velocity dispersions. For example, we confirm the previously reported\nnegative and positive galactocentric radial velocity gradients in the inner and\nouter disc, respectively. Here, we see them as part of a non-axisymmetric\nkinematic oscillation, and we map its azimuthal and vertical behaviour. We also\nwitness a new global arrangement of stars in the velocity plane of the solar\nneighbourhood and in distant regions in which stars are organised in thin\nsubstructures with the shape of circular arches that are oriented approximately\nalong the horizontal direction in the $U-V$ plane. Moreover, in distant\nregions, we see variations in the velocity substructures more clearly than ever\nbefore, in particular, variations in the velocity of the Hercules stream.\n(abridged)" }, { "anchor": "The Galactic center chimneys: The base of the multiphase outflow of the\n Milky Way: Outflows and feedback are key ingredients of galaxy evolution. Evidence for\nan outflow arising from the Galactic center (GC) has recently been discovered\nat different wavelength. We show that the X-ray, radio, and infrared emissions\nare deeply interconnected, affecting one another and forming coherent features\non scales of hundreds of parsecs, therefore indicating a common physical link\nassociated with the GC outflow. We debate the location of the northern chimney\nand suggest that it might be located on the front side of the GC because of a\nsignificant tilt of the chimneys toward us. We report the presence of strong\nshocks at the interface between the chimneys and the interstellar medium, which\nare traced by radio and warm dust emission. We observe entrained molecular gas\noutflowing within the chimneys, revealing the multiphase nature of the outflow.\nIn particular, the molecular outflow produces a long, strong, and structured\nshock along the northwestern wall of the chimney. Because of the different\ndynamical times of the various components of the outflow, the chimneys appear\nto be shaped by directed large-scale winds launched at different epochs. The\ndata support the idea that the chimneys are embedded in an (often dominant)\nvertical magnetic field, which likely diverges with increasing latitude. We\nobserve that the thermal pressure associated with the hot plasma appears to be\nsmaller than the ram pressure of the molecular outflow and the magnetic\npressure. This leaves open the possibility that either the main driver of the\noutflow is more powerful than the observed hot plasma, or the chimneys\nrepresent a \"relic\" of past and more powerful activity. These multiwavelength\nobservations corroborate the idea that the chimneys represent the channel\nconnecting the quasi-continuous, but intermittent, activity at the GC with the\nbase of the Fermi bubbles.", "positive": "Beyond halo mass: quenching galaxy mass assembly at the edge of\n filaments: We examine how the mass assembly of central galaxies depends on their\nlocation in the cosmic web. The HORIZON-AGN simulation is analysed at z~2 using\nthe DISPERSE code to extract multi-scale cosmic filaments. We find that the\ndependency of galaxy properties on large-scale environment is mostly inherited\nfrom the (large-scale) environmental dependency of their host halo mass. When\nadopting a residual analysis that removes the host halo mass effect, we detect\na direct and non-negligible influence of cosmic filaments. Proximity to\nfilaments enhances the build-up of stellar mass, a result in agreement with\nprevious studies. However, our multi-scale analysis also reveals that, at the\nedge of filaments, star formation is suppressed. In addition, we find clues for\ncompaction of the stellar distribution at close proximity to filaments. We\nsuggest that gas transfer from the outside to the inside of the haloes (where\ngalaxies reside) becomes less efficient closer to filaments, due to high\nangular momentum supply at the vorticity-rich edge of filaments. This quenching\nmechanism may partly explain the larger fraction of passive galaxies in\nfilaments, as inferred from observations at lower redshifts." }, { "anchor": "Proper motions and membership probabilities of stars in the region of\n open cluster NGC 3766: Relative proper motions and cluster membership probabilities have been\nderived for ~ 2500 stars in the field of the open star cluster NGC 3766. The\ncluster has been observed in $B$ and $V$ broadband filters at two epochs\nseparated by ~ 6 years using a wide-field imager mounted on the WFI@ESO2.2m\ntelescope. All CCD frames were reduced using the astrometric techniques\ndescribed in Anderson et al. (2006). The proper motion r.m.s. error for stars\nbrighter than $V$ ~ 15 mag is 2.0 mas/yr but it gradually increases up to ~4\nmas/yr at $V$ ~20 mag. Using proper motion data, membership probabilities have\nbeen derived for the stars in the region of the cluster. They indicate that\nthree Be and one Ap stars are member of the cluster. The reddening\n$E(B-V)=0.22\\pm0.05$ mag, a distance 2.5$\\pm$0.5 kpc and an age of ~ 20 Myr are\nderived using stars of $P_{\\mu}>70%$. Mass function slope $x=1.60\\pm0.10$ is\nderived for the cluster and cluster was found to be dynamically relaxed.\nFinally, we provide positions, calibrated $B$ and $V$ magnitudes, relative\nproper motions and membership probabilities for the stars in the field of NGC\n3766. We have produced a catalog that is electronically available to the\nastronomical community.", "positive": "Stellar diffusion in barred spiral galaxies: We characterize empirically the radial diffusion of stars in the plane of a\ntypical barred disk galaxy by calculating the local spatial diffusion\ncoefficient and diffusion time-scale for bulge-disk-halo N-body self-consistent\nsystems which initially differ in the Safronov-Toomre-Q_T parameter. We find\ndifferent diffusion scenarios that depend on the bar strength and on the degree\nof instability of the disk. Marginally stable disks, with Q_T \\sim 1, have two\nfamilies of bar orbits with different values of angular momentum and energy,\nwhich determine a large diffusion in the corotation region. In hot disks, Q_T>\n1, stellar diffusion is reduced with respect to the case of marginally stable\ndisks. In cold models, we find that spatial diffusion is not constant in time\nand strongly depends on the activity of the bar, which can move stars all over\nthe disk recurrently. We conclude that to realistically study the impact of\nradial migration on the chemical evolution modeling of the Milky Way the role\nof the bar has to be taken into account." }, { "anchor": "CFHTLenS: Weak lensing constraints on the ellipticity of galaxy-scale\n matter haloes and the galaxy-halo misalignment: We present weak lensing constraints on the ellipticity of galaxy-scale matter\nhaloes and the galaxy-halo misalignment. Using data from the\nCanada-France-Hawaii Telescope Lensing Survey (CFHTLenS), we measure the\nweighted-average ratio of the aligned projected ellipticity components of\ngalaxy matter haloes and their embedded galaxies, $f_\\mathrm{h}$, split by\ngalaxy type. We then compare our observations to measurements taken from the\nMillennium Simulation, assuming different models of galaxy-halo misalignment.\nUsing the Millennium Simulation we verify that the statistical estimator used\nremoves contamination from cosmic shear. We also detect an additional signal in\nthe simulation, which we interpret as the impact of intrinsic shape-shear\nalignments between the lenses and their large-scale structure environment.\nThese alignments are likely to have caused some of the previous observational\nconstraints on $f_\\mathrm{h}$ to be biased high. From CFHTLenS we find\n$f_\\mathrm{h}=-0.04 \\pm 0.25$ for early-type galaxies, which is consistent with\ncurrent models for the galaxy-halo misalignment predicting $f_\\mathrm{h}\\simeq\n0.20$. For late-type galaxies we measure $f_\\mathrm{h}=0.69_{-0.36}^{+0.37}$\nfrom CFHTLenS. This can be compared to the simulated results which yield\n$f_\\mathrm{h}\\simeq 0.02$ for misaligned late-type models.", "positive": "HI column density statistics of the cold neutral medium from absorption\n studies: Physical properties of the tiny scale structures in the cold neutral medium\n(CNM) of galaxies is a long-standing puzzle. Only a few lines of sights in our\nGalaxy have been studies with mixed results on the scale-invariant properties\nof such structures. Moreover, since these studies measure the variation of\nneutral hydrogen optical depth, they do not directly constrain the density\nstructures. In this letter, we investigate the possibility of measuring the\nproperties of density and spin temperature structures of the \\HI from\nabsorption studies of \\HI. Our calculations show that irrespective of the\nthermal properties of the clouds, the scale structure of the \\HI column density\ncan be estimated, whereas, \\HI absorption studies alone cannot shed much light\non either the amplitude of the density fluctuations and their temperature\nstructures. Detailed methodology and calculations with some fiducial examples\nare presented." }, { "anchor": "An investigation of open cluster Melotte 72 using Gaia DR2: The estimation of the main parameters of star clusters is significant in\nastrophysical studies. The most important aspect of using the Gaia DR2 survey\nlies in the positions, parallax, and proper motions of cluster stars with\nhomogeneous photometry that make the membership probability determine with high\naccuracy. In this respect, depending on Gaia DR2 database, an analysis of the\nopen star cluster Melotte 72 is taking place here. It is located at a distance\nof 2345+/-108 pc with an age of 1.0+/-0.5 Gyr. In studying the radial density\nprofile, the radius is found to be 5.0+/-0.15 arcmin. The reddening, the\nluminosity and mass functions, the total mass of the cluster, and the galactic\ngeometrical distances (X_Sun, Y_Sun, Z_Sun), and the distance from the galactic\ncenter (R_g ) have been estimated as well. Our study has shown a dynamical\nrelaxation behavior of Melotte 72.", "positive": "Gravitational microlensing as a probe for dark matter clumps: Extended dark matter (DM) substructures may play the role of microlenses in\nthe Milky Way and in extragalactic gravitational lens systems (GLSs). We\ncompare microlensing effects caused by point masses (Schwarzschild lenses) and\nextended clumps of matter using a simple model for the lens mapping. A\nsuperposition of the point mass and the extended clump is also considered. For\nspecial choices of the parameters, this model may represent a cusped clump of\ncold DM, a cored clump of self-interacting dark matter (SIDM) or an ultra\ncompact minihalo of DM surrounding a massive point-like object. We built the\nresulting micro-amplification curves for various parameters of one clump moving\nwith respect to the source in order to estimate differences between the light\ncurves caused by clumps and by point lenses. The results show that it may be\ndifficult to distinguish between these models. However, some region of the\nclump parameters can be restricted by considering the high amplification events\nat the present level of photometric accuracy. Then we estimate the statistical\nproperties of the amplification curves in extragalactic GLSs. For this purpose,\nan ensemble of amplification curves is generated yielding the autocorrelation\nfunctions (ACFs) of the curves for different choices of the system parameters.\nWe find that there can be a significant difference between these ACFs if the\nclump size is comparable with typical Einstein radii; as a rule, the\ncontribution of clumps makes the ACFs less steep." }, { "anchor": "3D Relativistic MHD numerical simulations of X-shaped radio sources: A significant fraction of extended radio sources presents a peculiar X-shaped\nradio morphology: in addition to the classical double lobed structure, radio\nemission is also observed along a second axis of simmetry in the form of\ndiffuse wings or tails. In a previous investigation we showed the existence of\na connection between the radio morphology and the properties of the host\ngalaxies. Motivated by this connection we performed two-dimensional numerical\nsimulations showing that X-shaped radio sources may naturally form as a jet\npropagates along the major axis a highly elliptical density distribution,\nbecause of the fast expansion of the cocoon along the minor axis of the\ndistribution.\n We intend to extend our analysis by performing three-dimensional numerical\nsimulations and investigating the role of different parameters is determining\nthe formation of the X-shaped morphology.\n The problem is addressed by numerical means, carrying out three-dimensional\nrelativistic magnetohydrodynamic simulations of bidirectional jets propagating\nin a triaxial density distribution.\n We show that only jets with power $\\lesssim 10^{44}$ erg s$^{-1}$ can give\norigin to an X-shaped morphology and that a misalignment of $30^o$ between the\njet axis and the major axis of the density distribution is still favourable to\nthe formation of this kind of morphology. In addition we compute synthetic\nradio emission maps and polarization maps.\n In our scenario for the formation of X-shaped radio sources only low power\nFRII can give origin to such kind of morphology. Our synthetic emission maps\nshow that the different observed morphologies of X-shaped sources can be the\nresult of similar structures viewed under different perspectives.", "positive": "Dwarf spheroidal $J$-factor likelihoods for generalized NFW profiles: Indirect detection strategies of particle Dark Matter (DM) in Dwarf\nspheroidal satellite galaxies (dSphs) typically entail searching for\nannihilation signals above the astrophysical background. To robustly compare\nmodel predictions with the observed fluxes of product particles, most analyses\nof astrophysical data -- which are generally frequentist -- rely on estimating\nthe abundance of DM by calculating the so-called $\\textit{J-factor}$. This\nquantity is usually inferred from the kinematic properties of the stellar\npopulation of a dSph using Jeans equation, commonly by means of Bayesian\ntechniques which entail the presence (and additional systematic uncertainty) of\nprior choice. Here, extending earlier work, we develop a scheme to derive the\nprofile likelihood for $J$-factors of dwarf spheroidals for models with five or\nmore free parameters. We validate our method on a publicly available simulation\nsuite, released by the Gaia Challenge, finding satisfactory statistical\nproperties for coverage and bias. We present the profile likelihood function\nand maximum likelihood estimates for the $J$-factor of ten dSphs . As an\nillustration, we apply these profiles likelihood to recently published analyses\nof gamma-ray data with the Fermi Large Area Telescope to derive new, consistent\nupper limits on the DM annihilation cross-section. We do this for a subset of\nsystems, generally referred to as $\\textit{classical dwarfs}$. The implications\nof these findings for DM searches are discussed, together with future\nimprovements and extensions of this technique." }, { "anchor": "Population synthesis of double neutron stars: Using the StarTrack binary population synthesis code we model the population\nof double neutron stars in the Galaxy. We include a detailed treatment of the\nspin evolution of each pulsar due to processes such as spin-down and spin-up\nduring accretion events as well as magnetic field decay. We also model the\nspatial distribution of double neutron stars by including their natal kicks and\nsubsequent propagation in the Galactic gravitational potential. This synthetic\npulsar population is compared to the observed sample of double neutron stars\ntaking into account the selection effects of detection in the radio band, to\ndetermine the most likely evolutionary parameters. With these parameters we\ndetermine the properties of the double neutron star binaries detectable in\ngravitational waves by the high frequency interferometers LIGO and VIRGO. In\nparticular, we discuss the distributions of chirp masses and mass ratios in\nsamples selected by their radio or gravitational wave emission.", "positive": "Hundreds of Low-Mass Active Galaxies in the Galaxy And Mass Assembly\n (GAMA) Survey: We present an entirely new sample of 388 low-mass galaxies ($M_\\star \\leq\n10^{10} M_\\odot$) that have spectroscopic signatures indicating the presence of\nmassive black holes (BHs) in the form of active galactic nuclei (AGNs) or tidal\ndisruption events (TDEs). Of these, 70 have stellar masses in the dwarf galaxy\nregime with $10^8 \\lesssim M_\\star/M_\\odot \\lesssim 10^{9.5}$. We identify the\nactive galaxies by analyzing optical spectra of a parent sample of $\\sim$23,000\nlow-mass emission-line galaxies in the Galaxy and Mass Assembly (GAMA) Survey\nData Release 4, and employing four different diagnostics based on narrow\nemission line ratios and the detection of high-ionization coronal lines. We\nfind that 47 of the 388 low-mass active galaxies exhibit broad H$\\alpha$ in\ntheir spectra, corresponding to virial BH masses in the range $M_{\\rm BH} \\sim\n10^{5.0-7.7} M_\\odot$ with a median BH mass of $\\langle M_{\\rm BH}\\rangle \\sim\n10^{6.2} M_\\odot$. Our sample extends to higher redshifts ($z \\le 0.3; \\langle\nz \\rangle=0.13$) than previous samples of AGNs in low-mass/dwarf galaxies based\non Sloan Digital Sky Survey spectroscopy, which can be attributed to the\nspectroscopic limit of GAMA being $\\sim 2$ magnitudes deeper. Moreover, our\nmulti-diagnostic approach has revealed low-mass active galaxies spanning a wide\nrange of properties, from blue star-forming dwarfs to luminous \"miniquasars\"\npowered by low-mass BHs. As such, this work has implications for BH seeding and\nAGN feedback at low masses." }, { "anchor": "The Underluminous Nature of Sgr A*: In the last several years, a number of observing campaigns of the massive\nblack hole Sgr A* has been carried out in order to address two important\nissues: one concerns the underluminous nature of Sgr A* with its bolometric\nluminosity being several orders of magnitude less than those of its more\nmassive counterparts. It turns out that the angular momentum of the ionized\nstellar winds from orbiting stars in one or two disks orbiting Sgr A* could be\na critical factor in estimating accurately the accretion rate unto Sgr A*. A\nnet angular momentum of ionized gas feeding Sgr A* could lower the Bondi rate.\nFurthermore, the recent time delay picture of the peak flare emission can be\nunderstood in the context of adiabatic expansion of hot plasma. The expansion\nspeed of the plasma is estimated to be sub-relativistic. However, relativistic\nbulk motion of the plasma could lead to outflow from Sgr A*. Significant\noutflow from Sgr A* could then act as a feedback which could then reduce Bondi\naccretion rate. These uncertain factors can in part explain the underluminous\nnature of Sgr A*. The other issue is related to the emission mechanism and the\ncause of flare activity in different wavelength bands. Modeling of X-ray and\nnear-IR flares suggests that inverse Compton scattering (ICS) of IR flare\nphotons by the energetic electrons responsible for the submm emission can\naccount for the X-ray flares. A time delay of minutes to tens of minutes is\npredicted between the peak flaring in the near-IR and X-rays, NOT due to\nadiabatic expansion of optically thick hot plasma, but to the time taken for IR\nflare photons to cross the accretion flow before being upscattered.", "positive": "The abundance of $z \\gtrsim 10$ galaxy candidates in the HUDF using deep\n JWST NIRCam medium-band imaging: We utilise JWST NIRCam medium-band imaging to search for extreme redshift ($z\n\\geq 9.5$) galaxy candidates in the Hubble Ultra Deep Field (HUDF) and the\nadditional pointing within the GOODS-South field provided by the second NIRCam\nmodule. Our search reveals 6 robust candidates, 3 of which have recently been\nspectroscopically confirmed. One of these 3 is the previously controversial $z\n\\simeq 12$ galaxy candidate UDF-22980 which is now detected in five JWST NIRCam\nmedium-band filters (F182M, F210M, F430M, F460M and F480M), efficiently\nexcluding alternative low-redshift solutions and allowing us to now report a\nsecure photometric redshift of $z = 11.6 \\pm 0.2$. We also detect 2 galaxies at\n$z \\geq 12.5$ including a newly-detected candidate in the imaging provided by\nthe second NIRCam module (south-west of the HUDF) at $z = 12.6 \\pm 0.6$. We\ndetermine the physical properties of the 6 galaxies by fitting the 14-band\nphotometry with Bagpipes. We find stellar masses of $\\log(M_{\\star}/{\\rm\n{M_{\\odot}}}) \\simeq 7.5 - 8.7$ and star-formation rates of\n$\\log(\\rm{SFR}/M_{\\odot}^{-1} \\rm{yr}^{-1}) \\simeq 0.3 - 5.0$. Despite the\nrelatively small cosmological volume covered by the HUDF itself and the second\nNIRCam module imaging, we find that the existence of these galaxies is fully\nconsistent with the latest measurements of both the UV luminosity function and\ncosmic star-formation rate density at $z\\simeq11$, supporting a gradual steady\ndecline in the cosmic star-formation rate density out to at least $z\\simeq15$." }, { "anchor": "Unveiling the Massive Stars in the Galactic Center: We present our recent efforts to unveil and understand the origin of massive\nstars outside the three massive star clusters in the Galactic Center. From our\nHST/NICMOS survey of the Galactic Center, we have identified 180 Paschen-alpha\nemitting sources, most of which should be evolved massive stars with strong\noptically thin stellar winds. Recently, we obtained Gemini GNIRS/NIFS H- and\nK-band spectra of eight massive stars near the Arches cluster. From their\nradial velocities, ages and masses, we suggest that in our sample, two stars\nare previous members of the Arches cluster, while other two stars embedded in\nthe H1/H2 HII regions formed in-situ.", "positive": "BUFFALO/Flashlights: Constraints on the abundance of lensed supergiant\n stars in the Spock galaxy at redshift 1: We present a constraint on the abundance of supergiant (SG) stars at redshift\nz approx. 1, based on recent observations of a strongly lensed arc at this\nredshift. First we derive a free-form model of MACS J0416.1-2403 using data\nfrom the BUFFALO program. The new lens model is based on 72 multiply lensed\ngalaxies that produce 214 multiple images, making it the largest sample of\nspectroscopically confirmed lensed galaxies on this cluster. The larger\ncoverage in BUFFALO allows us to measure the shear up to the outskirts of the\ncluster, and extend the range of lensing constraints up to ~ 1 Mpc from the\ncentral region, providing a mass estimate up to this radius. As an application,\nwe make predictions for the number of high-redshift multiply-lensed galaxies\ndetected in future observations with JWST. Then we focus on a previously known\nlensed galaxy at z=1.0054, nicknamed Spock, which contains four previously\nreported transients. We interpret these transients as microcaustic crossings of\nSG stars and compute the probability of such events. Based on simplifications\nregarding the stellar evolution, we find that microlensing (by stars in the\nintracluster medium) of SG stars at z=1.0054 can fully explain these events.\nThe inferred abundance of SG stars is consistent with either (1) a number\ndensity of stars with bolometric luminosities beyond the Humphreys-Davidson\n(HD) limit (L ~ $6\\times10^5 L_{\\odot}$) that is below 400 stars per sq. kpc,\nor (2) the absence of stars beyond the HD limit but with a SG number density of\n~ 9000 per sq. kpc for stars with luminosities between $10^5$ and\n$6\\times10^5$. This is equivalent to one SG star per 10x10 pc$^2$. We finally\nmake predictions for future observations with JWST's NIRcam. We find that in\nobservations made with the F200W filter that reach 29 mag AB, if cool red SG\nstars exist at z~1 beyond the HD limit, they should be easily detected in this\narc" }, { "anchor": "IAUS295 -- The Intriguing Life of Massive Galaxies: Introducing the\n Final Discussion: This is a brief introduction to the closing discussion of the IAU Symposium\n295, \"The Intriguing Life of Massive Galaxies\", that was held in Beijing from\nAugust 27 through 31, 2012. The discussion was focused on only four hot items,\nnamely 1) the redshift evolution of the size of passively evolving galaxies, 2)\nthe evolution with redshift of the specific star formation rate, 3) quenching\nof star formation in galaxies and dry merging, and 4) the IMF.", "positive": "Distribution of Radio Spectral Slopes of Galaxies in Optical Diagnostic\n Diagrams: For about 500 intermediate-redshift sources ($0.041.5 Re) stellar\npopulations for a subset of face-on systems using optical g-r versus r-z\ncolour/colour diagrams. The results are compared with those from control\nsamples that are defined without regard to atomic gas content, but are matched\nin redshift, stellar mass and structural parameters. HI-rich early-type (C>2.6)\nand late-type (C<2.6) galaxies are studied separately. When compared to the\ncontrol sample, the outer stellar populations of the majority of HI-rich\nearly-type galaxies are shifted in the colour/colour plane along a locus\nconsistent with younger stellar ages, but similar metallicities. The outer\ncolours of HI-rich late-type galaxies are much bluer in r-z than the HI-rich\nearly types, and we infer that they have outer disks which are both younger and\nmore metal-poor. We then proceed to analyze the galaxy environments of HI-rich\ngalaxies on scales of 500 kpc. HI-rich early-type galaxies with low (log M* <\n10.5) stellar masses differ significantly from the control sample in that they\nare more likely to be central rather than satellite systems. Their satellites\nare also less massive and have younger stellar populations. Similar, but weaker\neffects are found for low mass HI-rich late-type galaxies. In addition, we find\nthat the satellites of HI-rich late-types exhibit a greater tendency to align\nalong the major axis of the primary. No environmental differences are found for\nmassive (log M* > 10.5) HI-rich galaxies, regardless of type.", "positive": "The young Galactic cluster NGC 225: binary stars content and total mass\n estimate: Galactic star clusters are known to harbour a significant amount of binary\nstars, yet their role in the dynamical evolution of the cluster as a whole is\nnot comprehensively understood. We investigated the influence of binary stars\non the total mass estimate for the case of the moderately populated Galactic\nstar cluster NGC 225. The analysis of multi-epoch radial velocities of the 29\nbrightest cluster members, obtained over two observational campaigns, in\n1990-1991 and in 2019-2020, yields a value of binary fraction of $\\alpha =0.52$\n(15 stars out of 29). Using theoretical isochrones and Monte Carlo simulations\nwe found that the cluster mass increases at least 1.23 times when binaries are\nproperly taken into account. By combining Gaia EDR3 photometric data with our\nspectroscopic observations, we derived estimates of NGC 225 fundamental\nparameters as follows: mean radial velocity $ = -9.8 \\pm 0.7$ km s$^{-1}$,\n$\\log(\\tau)$=8.0-8.2 dex, distance $ D = 676 \\pm 22$ pc, and colour excess\n$E(B-V) = 0.29 \\pm 0.01$ mag." }, { "anchor": "UHZ1 and the other three most distant quasars observed: possible\n evidence for Supermassive Dark Stars: The James Webb Space Telescope (JWST) has recently uncovered a new\nrecord-breaking quasar, UHZ1, at a redshift of $z\\sim10$. This discovery\ncontinues JWST's trend of confronting the expectations from the standard\n$\\Lambda$CDM model of cosmology with challenges. Namely, too many very massive\ngalaxies and quasars have been observed at very high redshifts, when the\nuniverse was only a few hundred million years old. We have previously shown\nthat Supermassive Dark Stars (SMDSs) may offer a solution to this puzzle. These\nfascinating objects would be the first stars in the universe, growing to be\n$\\sim 10^5-10^7 M_{\\odot}$ and shining as bright as $10^9$ suns. Unlike\nPopulation III stars (the major alternative proposed model for the first stars\nin the universe, which would also have zero metallicity and would be powered by\nnuclear fusion), SMDSs would be powered by dark matter heating (e.g. dark\nmatter annihilation) and would be comparatively cooler. At the ends of their\nlives (when they run out of dark matter fuel), SMDSs would directly collapse\ninto black holes, thus providing possible seeds for the first quasars. Previous\npapers have shown that to form at $z\\sim10$, UHZ1 would require an incredibly\nmassive seed ($\\sim 10^4 -10^5 M_{\\odot}$), which was assumed to be a Direct\nCollapse Black Hole (DCBH). In this paper, we demonstrate that Supermassive\nDark Stars (SMDSs) offer an equally valid solution to the mystery of the first\nquasars, by examining the four most distant known quasars: UHZ1, J0313-1806,\nJ1342+0928, and J1007+2115, with particular emphasis on UHZ1.", "positive": "Interstellar Hydrides: Interstellar hydrides -- that is, molecules containing a single heavy element\natom with one or more hydrogen atoms -- were among the first molecules detected\noutside the solar system. They lie at the root of interstellar chemistry, being\namong the first species to form in initially-atomic gas, along with molecular\nhydrogen and its associated ions. Because the chemical pathways leading to the\nformation of interstellar hydrides are relatively simple, the analysis of the\nobserved abundances is relatively straightforward and provides key information\nabout the environments where hydrides are found. Recent years have seen rapid\nprogress in our understanding of interstellar hydrides, thanks largely to\nfar-IR and submillimeter observations performed with the Herschel Space\nObservatory. In this review, we will discuss observations of interstellar\nhydrides, along with the advanced modeling approaches that have been used to\ninterpret them, and the unique information that has thereby been obtained." }, { "anchor": "Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding\n 6: The existence of massive ($10^{11}$ solar masses) elliptical galaxies by\nredshift z~4 (when the Universe was 1.5 billion years old) necessitates the\npresence of galaxies with star-formation rates exceeding 100 solar masses per\nyear at z>6 (corresponding to an age of the Universe of less than 1 billion\nyears). Surveys have discovered hundreds of galaxies at these early cosmic\nepochs, but their star-formation rates are more than an order of magnitude\nlower. The only known galaxies with very high star-formation rates at z>6 are,\nwith only one exception, the host galaxies of quasars, but these galaxies also\nhost accreting supermassive (more than $10^9$ solar masses) black holes, which\nprobably affect the properties of the galaxies. Here we report observations of\nan emission line of singly ionized carbon ([CII] at a wavelength of 158\nmicrometres) in four galaxies at z>6 that are companions of quasars, with\nvelocity offsets of less than 600 kilometers per second and linear offsets of\nless than 600 kiloparsecs. The discovery of these four galaxies was\nserendipitous; they are close to their companion quasars and appear bright in\nthe far-infrared. On the basis of the [CII] measurements, we estimate\nstar-formation rates in the companions of more than 100 solar masses per year.\nThese sources are similar to the host galaxies of the quasars in [CII]\nbrightness, linewidth and implied dynamical masses, but do not show evidence\nfor accreting supermassive black holes. Similar systems have previously been\nfound at lower redshift. We find such close companions in four out of\ntwenty-five z>6 quasars surveyed, a fraction that needs to be accounted for in\nsimulations. If they are representative of the bright end of the [CII]\nluminosity function, then they can account for the population of massive\nelliptical galaxies at z~4 in terms of cosmic space density.", "positive": "Abundance ratios in dwarf elliptical galaxies: We determine abundance ratios of 37 dwarf ellipticals (dEs) in the nearby\nVirgo cluster. This sample is representative of the early-type population of\ngalaxies in the absolute magnitude range -19.0 < Mr < -16.0. We analyze their\nabsorption line-strength indices by means of index-index diagrams and scaling\nrelations and use the stellar population models to interpret them. We present\nages, metallicities and abundance ratios obtained from these dEs within an\naperture size of Re/8. We calculate [Na/Fe] from NaD, [Ca/Fe] from Ca4227 and\n[Mg/Fe] from Mgb. We find that [Na/Fe] is under-abundant with respect to solar\nwhile [Mg/Fe] is around solar. This is exactly opposite to what is found for\ngiant ellipticals, but follows the trend with metallicity found previously for\nthe Fornax dwarf NGC 1396. We discuss possible formation scenarios that can\nresult in such elemental abundance patterns and we speculate that dEs have\ndisk-like SFH favouring them to originate from late-type dwarfs or small\nspirals. Na-yields appear to be very metal-dependent, in agreement with studies\nof giant ellipticals, probably due to the large dependence on the\nneutron-excess in stars. We conclude that dEs have undergone a considerable\namount of chemical evolution, they are therefore not uniformly old, but have\nextended SFH, similar to many of the Local Group galaxies." }, { "anchor": "The Gas-Star Formation Cycle in Nearby Star-forming Galaxies II.\n Resolved Distributions of CO and H$\u03b1$ Emission for 49 PHANGS Galaxies: The relative distribution of molecular gas and star formation in galaxies\ngives insight into the physical processes and timescales of the cycle between\ngas and stars. In this work, we track the relative spatial configuration of CO\nand H$\\alpha$ emission at high resolution in each of our galaxy targets, and\nuse these measurements to quantify the distributions of regions in different\nevolutionary stages of star formation: from molecular gas without star\nformation traced by H$\\alpha$ to star-forming gas, and to HII regions. The\nlarge sample, drawn from the Physics at High Angular resolution in Nearby\nGalaxieS ALMA and narrowband H$\\alpha$ (PHANGS-ALMA and PHANGS-H$\\alpha$)\nsurveys, spans a wide range of stellar mass and morphological types, allowing\nus to investigate the dependencies of the gas-star formation cycle on global\ngalaxy properties. At a resolution of 150 pc, the incidence of regions in\ndifferent stages shows a dependence on stellar mass and Hubble type of galaxies\nover the radial range probed. Massive and/or earlier-type galaxies exhibit a\nsignificant reservoir of molecular gas without star formation traced by\nH$\\alpha$, while lower-mass galaxies harbor substantial HII regions that may\nhave dispersed their birth clouds or formed from low-mass, more isolated\nclouds. Galactic structures add a further layer of complexity to relative\ndistribution of CO and H$\\alpha$ emission. Trends between galaxy properties and\ndistributions of gas traced by CO and H$\\alpha$ are visible only when the\nobserved spatial scale is $\\ll$ 500 pc, reflecting the critical resolution\nrequirement to distinguish stages of star formation process.", "positive": "The Disruption of Dark Matter Minihalos by Successive Stellar Encounters: Scenarios such as the QCD axion with the Peccei-Quinn symmetry broken after\ninflation predict an enhanced matter power spectrum on sub-parsec scales. These\ntheories lead to the formation of dense dark matter structures known as\nminihalos, which provide insights into early Universe dynamics and have\nimplications for direct detection experiments. We examine the mass loss of\nminihalos during stellar encounters, building on previous studies that derived\nformulas for mass loss and performed N-body simulations. We propose a new\nformula for the mass loss that accounts for changes in the minihalo profile\nafter disruption by a passing star. We also investigate the mass loss for\nmultiple stellar encounters. We demonstrate that accurately assessing the mass\nloss in minihalos due to multiple stellar encounters necessitates considering\nthe alterations in the minihalo's binding energy after each encounter, as\noverlooking this aspect results in a substantial underestimation of the mass\nloss." }, { "anchor": "Discovery of two new hypervelocity stars from the LAMOST spectroscopic\n surveys: We report the discovery of two new unbound hypervelocity stars (HVSs) from\nthe LAMOST spectroscopic surveys. They are respectively a B2V type star of ~ 7\nM$_{\\rm \\odot}$ with a Galactic rest-frame radial velocity of 502 km/s at a\nGalactocentric radius of ~ 21 kpc and a B7V type star of ~ 4 M$_{\\rm \\odot}$\nwith a Galactic rest-frame radial velocity of 408 km/s at a Galactocentric\nradius of ~ 30 kpc. The origins of the two HVSs are not clear given their\ncurrently poorly measured proper motions. However, the future data releases of\nGaia should provide proper motion measurements accurate enough to solve this\nproblem. The ongoing LAMOST spectroscopic surveys are expected to yield more\nHVSs to form a statistical sample, providing vital constraint on understanding\nthe nature of HVSs and their ejection mechanisms.", "positive": "A Corona Australis cloud filament seen in NIR scattered light II:\n Comparison with sub-millimeter data: We study a northern part of the Corona Australis molecular cloud that\nconsists of a filament and a dense sub-millimetre core inside the filament. Our\naim is to measure dust temperature and sub-mm emissivity within the region. We\nalso look for confirmation that near-infrared (NIR) surface brightness can be\nused to study the structure of even very dense clouds. We extend our previous\nNIR mapping south of the filament. The dust colour temperatures are estimated\nusing Spitzer 160um and APEX/Laboca 870um maps. The column densities derived\nbased on the reddening of background stars, NIR surface brightness, and thermal\nsub-mm dust emission are compared. A three dimensional toy model of the\nfilament is used to study the effect of anisotropic illumination on\nnear-infrared surface brightness and the reliability of dust temperature\ndetermination. Relative to visual extinction, the estimated emissivity at 870um\nis kappa(870) = (1.3 +- 0.4) x 10^{-5} 1/mag. This is similar to the values\nfound in diffuse medium. A significant increase in the sub-millimetre\nemissivity seems to be excluded. In spite of saturation, NIR surface brightness\nwas able to accurately pinpoint, and better than measurements of the colour\nexcesses of background stars, the exact location of the column density maximum.\nBoth near- and far-infrared data show that the intensity of the radiation field\nis higher south of the filament." }, { "anchor": "Observaci\u00f3n de lentes gravitatorias con ALMA: Gravitational lensing is a fundamental tool for cosmology. A recent\ninstrument which will provide more information for models of these objects is\nALMA. Our goal is to select lens candidates to observe with ALMA and then model\nthem using GravLens Software. We had selected 12 quadruple images systems from\nthe CASTLES database, which show a high probability of observing extended\nsources in the submillimetric range. These new data will allow us to improve\nexisting models.\n Las lentes gravitatorias son una herramienta fundamental para la\ncosmolog\\'ia. Un nuevo instrumento que nos proporcionar\\'a mayor informaci\\'on\npara los modelos de estos objetos, es ALMA. Nuestro objetivo es seleccionar\nlentes candidatas para observar con ALMA y posteriormente modelarlas mediante\nel programa GravLens. Seleccionamos de la base de datos de CASTLES, 12 sistemas\ncu\\'adruples, los cuales tienen mayor probabilidad de observar fuentes\nextendidas en el rango submilim\\'etrico. Estos nuevos datos nos permitir\\'an\nmejorar los modelos exitentes para dichos sistemas.", "positive": "Dust evolution, a global view: III. Core/mantle grains, organic\n nano-globules, comets and surface chemistry: Within the framework of The Heterogeneous dust Evolution Model at the IaS\n(THEMIS) this work investigates in detail the surface processes and chemistry\nrelating to core/mantle interstellar and cometary grain structures and its\ninfluence on the nature of these fascinating particles. It appears that a\nrealistic consideration of the nature and chemical reactivity of interstellar\ngrain surfaces could self-consistently and within a coherent framework explain:\nthe anomalous oxygen depletion, the nature of the CO dark gas, the formation of\n'polar ice' mantles, the red wing on the 3 um water ice band, the basis for the\nO-rich chemistry observed in hot cores, the origin of organic nano-globules and\nthe \\sim 3.2 um 'carbonyl' absorption band observed in comet reflectance\nspectra. It is proposed that the reaction of gas phase species with\ncarbonaceous a- C(:H) grain surfaces in the interstellar medium, in particular\nthe incorporation of atomic oxygen into grain surfaces in epoxide functional\ngroups, is the key to explaining these observations. Thus, the chemistry of\ncosmic dust is much more intimately related with that of the interstellar gas\nthan has previously been considered. The current models for interstellar gas\nand dust chemistry will therefore most likely need to be fundamentally modified\nto include these new grain surface processes." }, { "anchor": "The near-to-mid infrared spectrum of quasars: We analyse a sample of 85 luminous (log(nuLnu(3\\um)/erg s-1)>45.5) quasars\nwith restframe ~2-11 \\um spectroscopy from AKARI and Spitzer. Their high\nluminosity allows a direct determination of the near-infrared quasar spectrum\nfree from host galaxy emission. A semi-empirical model consisting of a single\ntemplate for the accretion disk and two blackbodies for the dust emission\nsuccessfully reproduces the 0.1-10 \\um spectral energy distributions (SEDs).\nExcess emission at 1-2 \\um over the best-fitting model suggests that hotter\ndust is necessary in addition to the ~1200 K blackbody and the disk to\nreproduce the entire near-infrared spectrum. Variation in the extinction\naffecting the disk and in the relative strength of the disk and dust components\naccounts for the diversity of individual SEDs. Quasars with higher dust-to-disk\nluminosity ratios show slightly redder infrared continua and less prominent\nsilicate emission. We find no luminosity dependence in the shape of the average\ninfrared quasar spectrum. We generate a new quasar template that covers the\nrestframe range 0.1-11 \\um, and separate templates for the disk and dust\ncomponents. Comparison with other infrared quasar composites suggests that\nprevious ones are less reliable in the 2-4 \\um range. Our template is the first\none to provide a detailed view of the infrared emission on both sides of the 4\n\\um bump.", "positive": "Multi-Epoch Observations of Extremely High-Velocity Emergent Broad\n Absorption: We present the discovery of the highest velocity CIV broad absorption line to\ndate in the z=2.47 quasar SDSS J023011.28+005913.6, hereafter J0230. In\ncomparing the public DR7 and DR9 spectra of J0230, we discovered an emerging\nbroad absorption trough outflowing at ~60,000 km/s, which we refer to as trough\nA. In pursuing follow up observations of trough A, we discovered a second\nemergent CIV broad absorption trough outflowing at ~40,000 km/s, namely trough\nB. In total, we collected seven spectral epochs of J0230 that demonstrate\nemergent and rapidly (~10 days in the rest-frame) varying broad absorption. We\ninvestigate two possible scenarios that could cause these rapid changes: bulk\nmotion and ionization variability. Given our multi-epoch data, we were able to\nrule out some simple models of bulk motion, but have proposed two more\nrealistic models to explain the variability of both troughs. Trough A is likely\nan augmented `crossing disk' scenario with the absorber moving at 10,000 < v\n(km/s) < 18,000. Trough B can be explained by a flow-tube feature travelling\nacross the emitting region at 8,000 < v (km/s) < 56,000. If ionization\nvariability is the cause for the changes observed, trough A's absorber has n_e\n>= 724 cm^-3 and is at r_{equal} >=2.00 kpc, or is at r < 2.00 kpc with no\nconstraint on the density; trough B's absorber either has n_e >= 1540 cm^-3 and\nis at r_{equal} >= 1.37 kpc, or is at r < 1.37 kpc with no constraint on the\ndensity." }, { "anchor": "The VLA-COSMOS Survey: V. 324 MHz continuum observations: We present 90 cm VLA imaging of the COSMOS field, comprising a circular area\nof 3.14 square degrees at 8.0\"x6.0\" angular resolution with an average rms of\n0.5 mJy/beam. The extracted catalog contains 182 sources (down to 5.5sigma), 30\nof which are multi-component sources. Using Monte Carlo artificial source\nsimulations we derive the completeness of the catalog, and we show that our 90\ncm source counts agree very well with those from previous studies. Using X-ray,\nNUV-NIR and radio COSMOS data to investigate the population mix of our 90 cm\nradio sample, we find that our sample is dominated by active galactic nuclei\n(AGN). The average 90-20 cm spectral index (S_nu~nu**alpha, where S_nu is the\nflux density at frequency nu, and alpha the spectral index) of our 90 cm\nselected sources is -0.70, with an interquartile range of -0.90 to -0.53. Only\na few ultra-steep-spectrum sources are present in our sample, consistent with\nresults in the literature for similar fields. Our data do not show clear\nsteepening of the spectral index with redshift. Nevertheless, our sample\nsuggests that sources with spectral indices steeper than -1 all lie at z>1, in\nagreement with the idea that ultra-steep-spectrum radio sources may trace\nintermediate-redshift galaxies (z>1).", "positive": "The power spectrum and structure function of the Gamma Ray emission from\n the Large Magellanic Cloud: The Fermi-LAT observational data of the diffuse $\\gamma$ ray emission from\nthe Large Magellanic Cloud (LMC), were examined to test for the existence of\nunderlying long range correlations. A statistical test applied to the data\nindicated that the probability that data are random is $\\sim 10^{-99}$. Thus we\nproceeded and have used the counts-number data to compute 2D spatial\nautocorrelation, power spectrum, and structure function.\n The most important result of the present study is a clear indication for\nlarge scale spatial underlying correlations. This is evident in {\\bf all} the\nfunctions mentioned above. The 2D power spectrum has a logarithmic slope of -3\non large spatial scales and a logarithmic slope of -4 on small spatial scales.\nThe structure function has logarithmic slopes equaling 1 and 2 for the large\nand small scales respectively. The logarithmic slopes of the structure function\nand the power spectrum are consistent.\n A plausible interpretation of these results is the existence of a large scale\n{\\it compressible turbulence} with a 3D logarithmic slope of -4 extending over\nthe entire extent of the LMC. This may reflect the fact that the $\\gamma$ Ray\nemission is in star forming regions, where jets and shocks are abundant.\n Both the power spectrum and structure function exhibit steeper logarithmic\nslopes for smaller spatial scales. This is interpreted as an indication that\nthe turbulent region has an effective depth of about 1.5 kpc." }, { "anchor": "Entropy Driven Winds: Outflows and Fountains Lifted Gently by Buoyancy: We present a new theoretical framework for using entropy to understand how\noutflows driven by supernovae are launched from disc galaxies: via continuous,\nbuoyant acceleration through the circumgalactic medium (CGM). When young star\nclusters detonate supernovae in the interstellar medium (ISM) of a galaxy, they\ngenerate hot, diffuse bubbles that push on the surrounding ISM and evaporate\nthat ISM into their interiors. As these bubbles reach the scale height of the\nISM, they break out of the disc, rising into the CGM. Once these bubbles break\nout, if they have sufficiently high entropy, they will feel an upward\nacceleration, owing to a local buoyant force. This upward force will accelerate\nthese bubbles, driving them to high galactocentric radii, keeping them in the\nCGM for $>\\Gyr$, even if their initial velocity is much lower than the local\nescape velocity. We derive an equation of motion for these entropy-driven winds\nthat connects the ISM properties, halo mass, and CGM profile of galaxies to the\nultimate evolution of feedback-driven winds. We explore the parameter space of\nthese equations, and show how this novel framework can explain both\nself-consistent simulations of star formation and galactic outflows as well as\nthe new wealth of observations of CGM kinematics. We show that these\nentropy-driven winds can produce long wind recycling times, while still\ncarrying a significant amount of mass. Comparisons to simulations and\nobservations show entropy-driven winds convincingly explain the kinematics of\ngalactic outflows.", "positive": "A simple approach to CO cooling in molecular clouds: CO plays an important role in interstellar molecular clouds, both as a\ncoolant, and as a diagnostic molecule. However, a proper evaluation of the\ncooling rate due to CO requires a determination of the populations of many\nlevels, the spontaneous and stimulated radiative de-excitation rates between\nthese levels, and the transfer of the emitted multi-line radiation;\nadditionally, this must be done for three isotopologues. It would be useful to\nhave a simple analytic formulation that avoided these complications; this could\nthen be used in situations where CO plays an important role as a coolant, but\nthe details of this role are not the main concern. We derive such a formulation\nhere, by first considering the two asymptotic forms that obtain in the limits\nof (a) low volume-density and optical depth, and (b) high volume-density and\noptical depth. These forms are then combined in such a way as to fit the\ndetailed numerical results from Goldsmith \\& Langer (1978), which cover low\ntemperatures, and a range of physical conditions where the interplay of thermal\nand sub-thermal excitation, optical-depth effects, and the contributions from\nrare isotopologues, are all important. The fit is obtained using the\nMetropolis-Hastings method, and reproduces the results of GL78 well. It is a\npurely local and analytic function of state --- specifically a function of the\ndensity, $\\rho$, isothermal sound speed, $a$, CO abundance, $X_{_{\\rm CO}}$,\nand velocity divergence, $\\nabla\\cdot{\\boldsymbol\\upsilon}$. As an application,\nwe consider the cooling layer following a slow steady non-magnetic planar\nJ-shock. We show that, if the post-shock cooling is dominated by CO and its\nisotopologues, the thickness of the post-shock cooling layer is very small and\napproximately independent of the pre-shock velocity, $\\upsilon_o$, or pre-shock\nisothermal sound speed, $a_o$." }, { "anchor": "Resolved properties of classical bulge and pseudo-bulge galaxies: We compare properties of classical and pseudo-bulges and properties of their\nhosting galaxies selected from the MaNGA survey. Bulge types are identified\nbased on the S$\\mathrm{\\acute{e}}$rsic index n of bulge component and the\nposition of bulges on the Kormandy diagram. For the 393 classical bulges and\n422 pseudo-bulges selected and their hosting galaxies, we study their kinematic\nproperties including a proxy for specific angular momentum and central velocity\ndispersion, their stellar population properties including stellar age,\nmetallicity, and specific star formation rate, as well as HI fractions of the\ngalaxies. Our results show that at given stellar mass, disc components of\npseudo-bulge galaxies are younger, have more active star formation, rotate\nmore, and may contain more HI content compared with those of classical bulge\ngalaxies, and the differences are larger than those between bulges themselves.\nThe correlations between bulge types and disc properties indicate that\ndifferent types of bulges are shaped by different processes that may regulate\nboth growth of central components and evolution of outer discs in galaxies. In\naddition, we propose a stellar mass dependent divider of central velocity\ndispersion to separate galaxies with classical bulges from those with\npseudo-bulges in galaxy mass range of $10.4<\\mathrm{log}(M_*/M_\\odot)<11.4$:\n$\\mathrm{log}(\\sigma_0) = 0.23 \\times \\mathrm{log}(M_*/M_\\odot)-0.46$. Galaxies\nwith larger/smaller $\\sigma_0$ can be classified as hosts of\nclassical/pseudo-bulges.", "positive": "CLASH-VLT: Is there a dependence in metallicity evolution on galaxy\n structures?: We investigate the environmental dependence of the mass-metallicty (MZ)\nrelation and it's connection to galaxy stellar structures and morphologies. In\nour studies, we analyze galaxies in massive clusters at z~0.4 from the CLASH\n(HST) and CLASH-VLT surveys and measure their gas metallicities, star-formation\nrates, stellar structures and morphologies. We establish the MZ relation for 90\ncluster and 40 field galaxies finding a shift of ~-0.3 dex in comparison to the\nlocal trends seen in SDSS for the majority of galaxies with logM<10.5. We do\nnot find significant differences of the distribution of 4 distinct\nmorphological types that we introduce by our classification scheme (smooth,\ndisc-like, peculiar, compact). Some variations between cluster and field\ngalaxies in the MZ relation are visible at the high mass end. However, obvious\ntrends for cluster specific interactions (enhancements or quenching of SFRs)\nare missing. In particular, galaxies with peculiar stellar structures that hold\nsigns for galaxy interactions, are distributed in a similar way as disc-like\ngalaxies - in SFRs, masses and O/H abundances. We further show that our sample\nfalls around an extrapolation of the star-forming main sequence (the SFR-M*\nrelation) at this redshift, indicating that emission-line selected samples do\nnot have preferentially high star-formation rates (SFRs). However, we find that\nhalf of the high mass cluster members (M*>10^10Msun) lie below the main\nsequence which corresponds to the higher mass objects that reach solar\nabundances in the MZ diagram." }, { "anchor": "The Close AGN Reference Survey (CARS): Locating the [O III] wing\n component in luminous local Type 1 AGN: [Abridged]The strong asymmetry in the optical [O III]$\\lambda$5007 emission\nline is one of the best signatures of AGN-driven warm (~10$^4$ K) ionized gas\noutflows on host galaxy scales. While large spectroscopic surveys like SDSS\nhave characterized the kinematics of [O III] for large samples of AGN,\nestimating the associated energetics requires spatially resolving these\noutflows with, for example, IFU studies. As part of CARS we obtained\nspatially-resolved IFU spectroscopy for a representative sample of 39 luminous\ntype 1 AGN at 0.0180 % of the flux\nassociated with a point-like source. We measure <100 pc offsets in the spatial\nlocation of the outflow from the AGN nucleus using the spectro-astrometry\ntechnique for these sources. For the other 13 AGN, the [O III] wing emission is\nresolved and possibly extended on kpc scale. We conclude that [O III] wing\nemission can be compact or extended in an unbiased luminous AGN sample, where\nboth cases are likely to appear. Electron density in the compact [O III] wing\nregions (median $n_e$~1900 cm$^{-3}$) is nearly a magnitude higher than in the\nextended ones (median $n_e$~500 cm$^{-3}$). The presence of spatially extended\nand compact [O III] wing emission is unrelated to the AGN bolometric luminosity\nand to inclination effects, which means other features such as time delays, or\nmechanical feedback/radio jets may shape the ionized gas outflow properties.", "positive": "A Candidate Tidal Disruption Event in a Quasar at z=2.359 from Abundance\n Ratio Variability: A small fraction of quasars show an unusually high nitrogen-to-carbon ratio\n(N/C) in their spectra. These \"nitrogen-rich\" (N-rich) quasars are a\nlong-standing puzzle because their interstellar medium implies stellar\npopulations with abnormally high metallicities. It has recently been proposed\nthat N-rich quasars may result from tidal disruption events (TDEs) of stars by\nsupermassive black holes. The rapid enhancement of nitrogen and the depletion\nof carbon due to the carbon--nitrogen--oxygen cycle in supersolar mass stars\ncould naturally produce high N/C. However, the TDE hypothesis predicts that the\nN/C should change with time, which has never hitherto been observed. Here we\nreport the discovery of the first N-rich quasar with rapid N/C variability that\ncould be caused by a TDE. Two spectra separated by 1.7 years (rest-frame) show\nthat the N III]\\lambda 1750/C III]\\lambda 1909 intensity ratio decayed by\n~86%+/-14% (1 \\sigma). Optical (rest-frame UV) light-curve and X-ray\nobservations are qualitatively consistent with the TDE hypothesis; though, the\ntime baseline falls short of a definitive proof. Putting the single-object\ndiscovery into context, statistical analyses of the ~80 known N-rich quasars\nwith high-quality archival spectra show evidence (at a 5\\sigma\\ significance\nlevel) of a decrease in N/C on timescales of >1 year (rest-frame) and a\nconstant level of ionization (indicated by the C III]\\lambda 1909/C IV\\lambda\n1549 intensity ratio). If confirmed, our results demonstrate the method of\nidentifying TDE candidates in quasars via abundance ratio variability, opening\na new window of TDE observations at high redshift (z>2) with upcoming\nlarge-scale time-domain spectroscopic surveys." }, { "anchor": "Astro2020: How does dust escape from galaxies?: Whenever gas is blown out of a galaxy, chances are that it contains some\ncosmic dust. This dust is an important part of the metals budget for the\ncircumgalactic and intergalactic media, and traces the outflow and stripping\nhistory of the galaxy. The dust is also interesting in its own right, as dust\nplays an essential role in many astrophysical processes. We have only begun to\nlearn about circumgalactic dust, and in particular we do not know how (and\nwhen) it escapes its host galaxy. Here we describe the prospects for measuring\nthe dust mass and properties around many individual galaxies, which will form\nthe basis for understanding how the dust got there.", "positive": "The chemical composition of TS 01, the most oxygen-deficient planetary\n nebula. AGB nucleosynthesis in a metal-poor binary star: The planetary nebula TS 01 (also called PN G 135.9+55.9 or SBS 1150+599A),\nwith its record-holding low oxygen abundance and its double degenerate close\nbinary core (period 3.9 h), is an exceptional object located in the Galactic\nhalo. We have secured observational data in a complete wavelength range in\norder to pin down the abundances of half a dozen elements in the nebula. The\nabundances are obtained via detailed photoionization modelling taking into\naccount all the observational constraints (including geometry and aperture\neffects) using the pseudo-3D photoionization code Cloudy_3D. The spectral\nenergy distribution of the ionizing radiation is taken from appropriate model\natmospheres. Both stellar components contribute to the ionization: the ``cool''\none provides the bulk of hydrogen ionization, and the ``hot'' one is\nresponsible for the presence of the most highly charged ions, which explains\nwhy previous attempts to model the nebula experienced difficulties. The nebular\nabundances of C, N, O, and Ne are found to be respectively, 1/3.5, 1/4.2, 1/70,\nand 1/11 of the Solar value, with uncertainties of a factor 2. Thus the extreme\nO deficiency of this object is confirmed. The abundances of S and Ar are less\nthan 1/30 of Solar. Standard models of stellar evolution and nucleosynthesis\ncannot explain the abundance pattern observed in the nebula. To obtain an\nextreme oxygen deficiency in a star whose progenitor has an initial mass of\nabout 1 msun requires an additional mixing process, which can be induced by\nstellar rotation and/or by the presence of the close companion. We have\ncomputed a stellar model with initial mass of 1 msun, appropriate metallicity,\nand initial rotation of 100 kms, and find that rotation greatly improves the\nagreement between the predicted and observed abundances." }, { "anchor": "Physical properties of more than one thousand brightest cluster galaxies\n detected in the Canada France Hawaii Telescope Legacy Survey: Brightest cluster galaxies (BCGs) are very massive elliptical galaxies found\nat the centers of clusters. Their study gives clues on the formation and\nevolution of the clusters in which they are embedded. We analysed here in a\nhomogeneous way the properties of a sample of more than one thousand BCGs in\nthe redshift range 0.15 < z < 0.7, based on images from the Canada France\nHawaii Telescope Legacy Survey. Based on the cluster catalogue of 1371 clusters\nby Sarron et al. (2018), we applied our automatic BCG detection algorithm and\nidentified successfully 70% of the BCGs in our sample. We analysed their 2D\nphotometric properties with GALFIT. We also compared the position angles of the\nBCG major axes with those of the overall cluster to which they belong. We found\nno evolution of the BCG properties with redshift up to z = 0.7, in agreement\nwith previous results by Chu et al. (2021), who analysed an order of magnitude\nsmaller sample, but reaching a redshift z = 1.8. The Kormendy relation for BCGs\nis tight and consistent with that of normal elliptical galaxies and BCGs\nmeasured by other authors. The position angles of the BCGs and of the cluster\nto which they belong agree within 30 degrees for 55% of the objects with well\ndefined position angles. The study of this very large sample of more than one\nthousand BCGs shows that they were mainly formed before z = 0.7, as we find no\nsignificant growth for the luminosities and sizes of central galaxies. We\ndiscuss the importance of the intracluster light in the interpretation of these\nresults. We highlight the role of image depth in the modelisation of the\nluminosity profiles of BCGs, and give evidence for the presence of an inner\nstructure which can only be resolved on deep surveys with limiting apparent\nmagnitude at 80% completeness m80 > 26 mag/arcsec2.", "positive": "The BLAST View of the Star Forming Region in Aquila (ell=45deg,b=0deg): We have carried out the first general submillimeter analysis of the field\ntowards GRSMC 45.46+0.05, a massive star forming region in Aquila. The\ndeconvolved 6 deg^2 (3\\degree X 2\\degree) maps provided by BLAST in 2005 at\n250, 350, and 500 micron were used to perform a preliminary characterization of\nthe clump population previously investigated in the infrared, radio, and\nmolecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to\ncharacterize the Ultracompact HII regions (UCHIIRs) within the main clumps. By\nmeans of the BLAST maps we have produced an initial census of the submillimeter\nstructures that will be observed by Herschel, several of which are known\nInfrared Dark Clouds (IRDCs). Our spectral energy distributions of the main\nclumps in the field, located at ~7 kpc, reveal an active population with\ntemperatures of T~35-40 K and masses of ~10^3 Msun for a dust emissivity index\nbeta=1.5. The clump evolutionary stages range from evolved sources, with\nextended HII regions and prominent IR stellar population, to massive young\nstellar objects, prior to the formation of an UCHIIR.The CORNISH data have\nrevealed the details of the stellar content and structure of the UCHIIRs. In\nmost cases, the ionizing stars corresponding to the brightest radio detections\nare capable of accounting for the clump bolometric luminosity, in most cases\npowered by embedded OB stellar clusters." }, { "anchor": "Cholla-MHD: An Exascale-Capable Magnetohydrodynamic Extension to the\n Cholla Astrophysical Simulation Code: We present an extension of the massively parallel, GPU native, astrophysical\nhydrodynamics code Cholla to magnetohydrodynamics (MHD). Cholla solves the\nideal MHD equations in their Eulerian form on a static Cartesian mesh utilizing\nthe Van Leer + Constrained Transport integrator, the HLLD Riemann solver, and\nreconstruction methods at second and third order. Cholla's MHD module can\nperform over 200 million cell updates per GPU-second while using the HLLD\nRiemann solver and second order reconstruction. The inherently parallel nature\nof GPUs combined with increased memory in new hardware allows Cholla's MHD\nmodule to perform simulation with resolutions of $>450^3$ cells on a single\nGPU. We employ GPU direct MPI to attain nearly perfect weak scaling on the\nexascale supercomputer \\textit{Frontier}, while using up to 74,000 GPUs and\nsimulating a total grid size of over 1.2 trillion cells. A suite of test\nproblems highlights the accuracy of Cholla's MHD module and demonstrates that\nzero magnetic divergence in solutions is maintained to round off error. We also\npresent new testing and continuous integration tools using GoogleTest, GitHub\nActions, and Jenkins that have made development more robust and accurate and\nensure reliability in the future.", "positive": "The quiescent phase of galactic disc growth: We perform a series of controlled N-body simulations of growing disc galaxies\nwithin non-growing, live dark matter haloes of varying mass and concentration.\nOur initial conditions include either a low-mass disc or a compact bulge. New\nstellar particles are continuously added on near-circular orbits to the\nexisting disc, so spiral structure is continuously excited. To study the effect\nof combined spiral and giant molecular cloud (GMC) heating on the discs we\nintroduce massive, short-lived particles that sample a GMC mass function. An\nisothermal gas component is introduced for a subset of the models. We perform a\nresolution study and vary parameters governing the GMC population, the\nhistories of star formation and radial scale growth. Models with GMCs and\nstandard values for the disc mass and halo density provide the right level of\nself-gravity to explain the age velocity dispersion relation of the Solar\nneighbourhood (Snhd). GMC heating generates remarkably exponential vertical\nprofiles with scaleheights that are radially constant and agree with\nobservations of galactic thin discs. GMCs are also capable of significantly\ndelaying bar formation. The amount of spiral induced radial migration agrees\nwith what is required for the metallicity distribution of the Snhd. However, in\nour standard models the outward migrating populations are not hot enough\nvertically to create thick discs. Thick discs can form in models with high\nbaryon fractions, but the corresponding bars are too long, the young stellar\npopulations too hot and the discs flare considerably." }, { "anchor": "Measuring the ICM velocity structure in the Ophiuchus cluster: We have found evidence of bulk velocities following active galactic nucleus\n(AGN) bubbles in the Virgo cluster and galaxy motions in the Centaurus cluster.\nIn order to increase the sample and improve our understanding of the\nintracluster medium (ICM), we present the results of a detailed mapping of the\nOphiuchus cluster with {\\it XMM-Newton} to measure bulk flows through very\naccurate Fe~K measurements. To measure the gas velocities we use a novel\nEPIC-pn energy scale calibration, which uses the Cu K$\\alpha$ instrumental line\nas reference for the line emission. We created 2D spectral maps for the\nvelocity, metallicity, temperature, density, entropy and pressure with a\nspatial resolution of 0.25$'$ ($\\sim 26$~kpc). The ICM velocities in the\ncentral regions where AGN feedback is most important are similar to the\nvelocity of the brightest cluster galaxy (BCG). We have found a large interface\nregion where the velocity changes abruptly from blueshifted to redshifted gas\nwhich follows a sharp surface brightness discontinuity. We also found that the\nmetallicities and temperatures do not change as we move outwards from the giant\nradio fossil previously identified in radio observations of the cluster.\nFinally, we have found a contribution from the kinetic component of $<25\\%$to\nthe total energy budget for large distances.", "positive": "Not In Our Backyard: Spectroscopic Support for the CLASH z=11 Candidate\n MACS0647-JD: We report on our first set of spectroscopic Hubble Space Telescope\nobservations of the z~11 candidate galaxy strongly lensed by the\nMACSJ0647.7+7015 galaxy cluster. The three lensed images are faint and we show\nthat these early slitless grism observations are of sufficient depth to\ninvestigate whether this high-redshift candidate, identified by its strong\nphotometric break at ~1.5 micron, could possibly be an emission line galaxy at\na much lower redshift. While such an interloper would imply the existence of a\nrather peculiar object, we show here that such strong emission lines would\nclearly have been detected. Comparing realistic, two-dimensional simulations to\nthese new observations we would expect the necessary emission lines to be\ndetected at >5 sigma while we see no evidence for such lines in the dispersed\ndata of any of the three lensed images. We therefore exclude that this object\ncould be a low redshift emission line interloper, which significantly increases\nthe likelihood of this candidate being a bona fide z~11 galaxy." }, { "anchor": "When Gas Dynamics Decouples from Galactic Rotation: Characterizing ISM\n Circulation in Disk Galaxies: In galactic disks, galactic rotation sets the bulk motion of gas, and its\nenergy and momentum can be transferred toward small scales. Additionally, in\nthe interstellar medium, random and noncircular motions arise from stellar\nfeedback, cloud-cloud interactions, and instabilities, among other processes.\nOur aim is to comprehend to which extent small-scale gas dynamics is decoupled\nfrom galactic rotation. We study the relative contributions of galactic\nrotation and local noncircular motions to the circulation of gas, $\\Gamma$, a\nmacroscopic measure of local rotation, defined as the line integral of the\nvelocity field around a closed path. We measure the circulation distribution as\na function of spatial scale in a set of simulated disk galaxies and we model\nthe velocity field as the sum of galactic rotation and a Gaussian random field.\nThe random field is parameterized by a broken power law in Fourier space, with\na break at the scale $\\lambda_c$. We define the spatial scale $\\lambda_{\\rm\neq}$ at which galactic rotation and non-circular motions contribute equally to\n$\\Gamma$. For our simulated galaxies, the gas dynamics at the scale of\nmolecular clouds is usually dominated by noncircular motions, but in the center\nof galactic disks galactic rotation is still relevant. Our model shows that the\ntransfer of rotation from large scales breaks at the scale $\\lambda_c$ and this\ntransition is necessary to reproduce the circulation distribution. We find that\n$\\lambda_{\\rm eq}$, and therefore the structure of the gas velocity field, is\nset by the local conditions of gravitational stability and stellar feedback.", "positive": "Supernova induced processing of interstellar dust: impact of ISM gas\n density and gas turbulence: Quantifying the efficiency of dust destruction in the interstellar medium\n(ISM) due to supernovae (SNe) is crucial for the understanding of galactic dust\nevolution. We present 3D hydrodynamic simulations of an SN blast wave\npropagating through the ISM. The interaction between the forward shock of the\nremnant and the surrounding ISM leads to destruction of ISM dust by the shock\nheated gas. We consider the dust processing due to ion sputtering, accretion of\natoms/molecules and grain-grain collisions. Using 2D slices from the simulation\ntimeseries, we apply post-processing calculations using the Paperboats code. We\nfind that efficiency of dust destruction depends strongly on the rate of grain\nshattering due to grain-grain collisions. The effective dust destruction is\nsimilar to previous theoretical estimates when grain-grain collisions are\nomitted, but with grain shattering included, the net destruction efficiency is\nroughly one order of magnitude higher. This result indicates that the dust\ndestruction rate in the ISM may have been severely underestimated in previous\nwork, which only exacerbates the dust-budget crises seen in galaxies at high\nredshifts." }, { "anchor": "The conformity of HI galaxies in ALFALFA-SDSS sample: The conformity effect, indicating the evolution of a galaxy is related to its\nsurrounding neighbour galaxies as far as a few Mpc, is an interesting\nphenomenon in the modeling of galaxy and evolution. Here we study the\nconformity effect of HI galaxies in a matched galaxy sample between SDSS DR7\nand ALFALFA surveys. By checking the probability difference for the detected HI\ngalaxies as a function of distance around a normal or an HI galaxy, we find\nthat this effect is significant out to 5 Mpc. It also shows a dependence on the\nstellar mass of galaxies, with the strength the strongest in the stellar mass\nrange of 10^10~10^10.5. However, when the sample is confined to central\ngalaxies in groups with virial radii smaller than 1 Mpc, the 1-halo conformity\nsignal is still evident, while the 2-halo conformity signal is reduced to a\nvery weak amplitude. Our results confirm the previous study in the optical band\nthat the 2-halo term is possibly caused by the bias effect in the sample\nselection. Furthermore, we confirm the existence of the 1-halo conformity\ndiscovered in the optical and radio band in previous lectures. Our results\nprovide another viewpoint of the conformity effect and hope to shed the light\non the co-evolution of the galaxies and their neighbours in the current galaxy\nformation models.", "positive": "Does the X-ray outflow quasar PDS 456 have a UV outflow at 0.3c?: The quasar PDS 456 (at redshift ~0.184) has a prototype ultra-fast outflow\n(UFO) measured in X-rays. This outflow is highly ionized with relativistic\nspeeds, large total column densities log N_H(cm^-2) > 23, and large kinetic\nenergies that could be important for feedback to the host galaxy. A UV spectrum\nof PDS 456 obtained with the Hubble Space Telescope in 2000 contains one\nwell-measured broad absorption line (BAL) at ~1346A (observed) that might be\nLy-alpha at v ~ 0.06c or NV 1240 at v ~ 0.08c. However, we use photoionisation\nmodels and comparisons to other outflow quasars to show that these BAL\nidentifications are problematic because other lines that should accompany them\nare not detected. We argue that the UV BAL is probably CIV 1549 at v ~ 0.30c.\nThis would be the fastest UV outflow ever reported, but its speed is similar to\nthe X-ray outflow and its appearance overall is similar to relativistic UV BALs\nobserved in other quasars. The CIV BAL identification is also supported\nindirectly by the tentative detection of another broad CIV line at v ~ 0.19c.\nThe high speeds suggest that the UV outflow originates with the X-ray UFO\ncrudely 20 to 30 r_g from the central black hole. We speculate that the CIV BAL\nmight form in dense clumps embedded in the X-ray UFO, requiring density\nenhancements of only >0.4 dex compared clumpy structures already inferred for\nthe soft X-ray absorber in PDS 456. The CIV BAL might therefore be the first\ndetection of low-ionisation clumps proposed previously to boost the opacities\nin UFOs for radiative driving." }, { "anchor": "SuperBoRG: Exploration of point sources at $z\\sim8$ in HST parallel\n fields: To extend the search for quasars in the epoch of reionization beyond the tip\nof the luminosity function, we explore point source candidates at redshift\n$z\\sim8$ in SuperBoRG, a compilation of $\\sim$0.4deg$^2$ archival medium-deep\n($m_{\\rm F160W}\\sim 26.5$ABmag, 5$\\sigma$) parallel IR images taken with the\nHubble Space Telescope (HST). Initial candidates are selected by using the\nLyman-break technique. We then carefully analyze source morphology, and\nrobustly identify 3 point sources at $z\\sim8$. Photometric redshift analysis\nreveals that they are preferentially fit by extra-galactic templates, and we\nconclude that they are unlikely to be low-$z$ interlopers, including brown\ndwarfs. A clear IRAC ch2 flux excess is seen in one of the point sources, which\nis expected if the source has strong H$\\beta$+[O III] emission with rest-frame\nequivalent width of $\\sim3000$AA. Deep spectroscopic data taken with\nKeck/MOSFIRE, however, do not reveal Ly$\\alpha$ emission from the object. In\ncombination with the estimated H$\\beta$+[O III] equivalent width, we place an\nupper limit on its Ly$\\alpha$ escape fraction $f_{\\rm esc, Ly\\alpha}< 2 \\%$. We\nestimate the number density of these point sources\n$\\sim1\\times10^{-6}$Mpc$^{-3}$mag$^{-1}$ at $M_{\\rm UV}\\sim-23$mag. The final\ninterpretation of our results remains inconclusive: extrapolation from low-$z$\nstudies of $faint$ quasars suggests that $>100\\times$ survey volume may be\nrequired to find one of this luminosity. The James Webb Space Telescope will be\nable to conclusively determine the nature of our luminous point source\ncandidates, while the Roman Space Telescope will probe $\\sim 200$ times the\narea of the sky with the same observing time considered in this HST study.", "positive": "Impact of turbulence intensity and fragmentation velocity on dust\n particle size evolution and non-ideal magnetohydrodynamics effects: We investigate the influence of dust particle size evolution on non-ideal\nmagnetohydrodynamic effects during the collapsing phase of star-forming cores,\ntaking both the turbulence intensity in the collapsing cloud core and the\nfragmentation velocity of dust particles as parameters. When the turbulence\nintensity is small, the dust particles do not grow significantly, and the\nnon-ideal MHD effects work efficiently in high-density regions. The dust\nparticles rapidly grow in a strongly turbulent environment, while the\nefficiency of non-ideal MHD effects in such an environment depends on the\nfragmentation velocity of the dust particles. When the fragmentation velocity\nis small, turbulence promotes coagulation growth and collisional fragmentation\nof dust particles, producing small dust particles. In this case, the adsorption\nof charged particles on the dust particle surfaces becomes efficient and the\nabundance of charged particles decreases, making non-ideal MHD effects\neffective at high densities. On the other hand, when the fragmentation velocity\nis high, dust particles are less likely to fragment, even if the turbulence is\nstrong. In this case, the production of small dust particles become inefficient\nand non-ideal MHD effects become less effective. We also investigate the effect\nof the dust composition on the star and disk formation processes. We constrain\nthe turbulence intensity of a collapsing core and the fragmentation velocity of\ndust for circumstellar disk formation due to the dissipation of the magnetic\nfield." }, { "anchor": "Young stellar population gradients in central cluster galaxies from NUV\n and optical spectroscopy: Central cluster galaxies are the largest and most massive galaxies in the\nUniverse. Although they host very old stellar populations, several studies\nfound the existence of blue cores in some BCGs indicating ongoing star\nformation. We analyse VLT/X-Shooter stacked spectra of 6 nearby massive central\ngalaxies with high central velocity dispersions ($\\sigma$>300 km/s) at\ndifferent galactocentric distances. We quantify the young stellar population\nout to 4 kpc by fitting near-UV and optical absorption line indices with\npredictions of composite stellar populations modelled by an old and a young\nstellar component. We also use IMF-sensitive indices since these galaxies have\nbeen found to host a bottom-heavy IMF in their central regions. We derive\nnegative young stellar populations gradients, with mass fractions of stars\nyounger than 1 Gyr decreasing with galactocentric distance, from 0.70% within\n0.8 kpc to zero beyond 2 kpc. We also measure the mass fraction in young stars\nfor individual galaxies in the highest S/N central regions. All the galaxies\nhave young components of less than one percent. Our results clearly suggest\nthat the star formation in massive central cluster galaxies takes place in\ntheir galaxy cores (<2 kpc), which, with deeper gravitational potential wells,\nare capable of retaining more gas. Among the possible sources for the gas\nrequired to form these young stars, our results are consistent with an in-situ\norigin via stellar evolution, which is sufficient to produce the observed young\nstellar populations.", "positive": "Optical Observations of star clusters NGC 1513 and NGC 4147; white dwarf\n WD1145+017 and $K$ band imaging of star forming region Sh2-61 with the 3.6\n meter Devasthal Optical Telescope: The $UBVRI$ CCD photometric data of open star cluster NGC 1513 are obtained\nwith the 3.6-m Indo-Belgian Devasthal optical telescope (DOT). Analyses of the\nGAIA EDR3 astrometric data have identified 106 possible cluster members. The\nmean proper motion of the cluster is estimated as\n$\\mu_{\\alpha}Cos{\\delta}=1.29\\pm0.02$ and $\\mu_{\\delta}=-3.74\\pm0.02$ mas\nyr$^{-1}$. Estimated values of reddening $E(B-V)$ and distance to the NGC 1513\nare 0.65$\\pm$0.03 mag and 1.33$\\pm$0.1 kpc respectively. An age of $225\\pm25$\nMyr is assigned to the cluster by comparing theoretical isochrones with deep\nobserved cluster sequence. Using observations taken with the 3.6-m DOT, values\nof distance and age of the galactic globular cluster NGC 4147 are estimated as\n$18.2\\pm0.2$ Kpc and $14\\pm2$ Gyr respectively. The optical observations of\nplanetary transit around white dwarf WD1145+017 and $K$-band imaging of\nstar-forming region Sharpless Sh 2-61 demonstrate observing capability of 3.6-m\nDOT. Optical and near-infrared observations of celestial objects and events are\nbeing carried out routinely with the 3.6-m DOT. They indicate that the\nperformance of the telescope is at par with those of other similar telescopes\nlocated elsewhere in the world. We therefore state that this observing facility\naugurs well for multi-wavelength astronomy including study of astrophysical\njets." }, { "anchor": "The fourth data release of the Kilo-Degree Survey: ugri imaging and\n nine-band optical-IR photometry over 1000 square degrees: The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey\nwith the OmegaCAM camera at the VLT Survey Telescope, specifically designed for\nmeasuring weak gravitational lensing by galaxies and large-scale structure.\nWhen completed it will consist of 1350 square degrees imaged in four filters\n(ugri). Here we present the fourth public data release which more than doubles\nthe area of sky covered by data release 3. We also include aperture-matched\nZYJHKs photometry from our partner VIKING survey on the VISTA telescope in the\nphotometry catalogue. We illustrate the data quality and describe the catalogue\ncontent. Two dedicated pipelines are used for the production of the optical\ndata. The Astro-WISE information system is used for the production of co-added\nimages in the four survey bands, while a separate reduction of the r-band\nimages using the theli pipeline is used to provide a source catalogue suitable\nfor the core weak lensing science case. All data have been re-reduced for this\ndata release using the latest versions of the pipelines. The VIKING photometry\nis obtained as forced photometry on the theli sources, using a re-reduction of\nthe VIKING data that starts from the VISTA pawprints. Modifications to the\npipelines with respect to earlier releases are described in detail. The\nphotometry is calibrated to the Gaia DR2 G band using stellar locus regression.\nIn this data release a total of 1006 square-degree survey tiles with stacked\nugri images are made available, accompanied by weight maps, masks, and\nsingle-band source lists. We also provide a multi-band catalogue based on\nr-band detections, including homogenized photometry and photometric redshifts,\nfor the whole dataset. Mean limiting magnitudes (5 sigma in a 2\" aperture) are\n24.23, 25.12, 25.02, 23.68 in ugri, respectively, and the mean r-band seeing is\n0.70\".", "positive": "Spectroscopic Identification and Chemical Distribution of HII Regions in\n the Galactic Anti-center Area from LAMOST: We spectroscopically identify 101 Galactic HII regions using spectra from the\nLarge Sky Area Multi- Object Fiber Spectroscopic Telescope (LAMOST) survey,\ncross-matched with an HII region catalog derived from the all-sky Wide-Field\nInfrared Survey Explorer(WISE) data. Among all HII regions in our sample, 47\nsources are newly confirmed. Spatially, most of our identified HII regions are\nlocated in the anti-center area of the Galaxy. For each of the HII regions, we\naccurately extract and measure the nebular emission lines of the spectra, and\nestimate the oxygen abundances using the strong-line method. We focus on the\nabundance distribution of HII regions in the Galactic anti-center area.\nAccordingly, we derive the oxygen abundance gradient with a slope of -0.036\n+/-0.004 dex/kpc, covering a range of RG from 8.1 to 19.3 kpc. In particular,\nwe also fit the outer disk objects with a slope of -0.039 +/- 0.012 dex /kpc,\nwhich indicates that there is no flattening of the radial oxygen gradient in\nthe outer Galactic disk." }, { "anchor": "Angular momentum variation of the Milky Way thick disk: The dependence\n of chemical abundance and the evidence on inside-out formation scenario: We investigate the angular momentum of mono-abundance populations (MAPs) of\nthe Milky Way thick disk by using a sample of 26,076 giant stars taken from\nAPOGEE DR17 and Gaia EDR3. The vertical and perpendicular angular momentum\ncomponents, $L_Z$ and $L_P$, of MAPs in narrow bins have significant variations\nacross the [$\\alpha$/M]-[M/H] plane. $L_Z$ and $L_P$ systematically change with\n[M/H] and [$\\alpha$/M] and can be alternatively quantified by the chemical\ngradients: $d[{\\rm M/H}]/dL_Z = 1.2\\times 10^{-3}\n$\\,dex\\,kpc$^{-1}$\\,km$^{-1}$\\,s, $d{\\rm [M/H]}/dL_P = -5.0\\times\n10^{-3}$\\,dec\\,kpc$^{-1}$\\,km$^{-1}$\\,s, and $d[\\alpha/{\\rm M}]/dL_Z =\n-3.0\\times 10^{-4} $\\,dex\\,kpc$^{-1}$\\,km$^{-1}$\\,s, $d[\\alpha/{\\rm M}]/dL_P =\n1.2\\times 10^{-3}$\\,dec\\,kpc$^{-1}$\\,km$^{-1}$\\,s. These correlations can also\nbe explained as the chemical-dependence of the spatial distribution shape of\nMAPs. We also exhibit the corresponding age dependence of angular momentum\ncomponents. Under the assumption that the guiding radius ($R_g$) is\nproportional to $L_Z$, it provides direct observational evidence of the\ninside-out structure formation scenario of the thick disk, with $dR_g/dAge =\n-1.9$\\,kpc\\,Gyr$^{-1}$. The progressive changes in the disk thickness can be\nexplained by the upside-down formation or/and the consequent kinematical\nheating.", "positive": "Line emission from filaments in molecular clouds: Filamentary structures are often identified in column density maps of\nmolecular clouds, and appear to be important for both low- and high-mass star\nformation. Theoretically, these structures are expected to form in regions\nwhere the supersonic cloud-scale turbulent velocity field converges. While this\nmodel of filament formation successfully reproduces several of their properties\nderived from column densities, it is unclear whether it can also reproduce\ntheir kinematic features. We use a combination of hydrodynamical, chemical and\nradiative transfer modelling to predict the emission properties of these\ndynamically-forming filaments in the $^{13}$CO, HCN and N$_2$H$^+$ $J=1-0$\nrotational lines. The results are largely in agreement with observations; in\nparticular, line widths are typically subsonic to transonic, even for filaments\nwhich have formed from highly supersonic inflows. If the observed filaments are\nformed dynamically, as our results suggest, no equilibrium analysis is\npossible, and simulations which presuppose the existence of a filament are\nlikely to produce unrealistic results." }, { "anchor": "The formation of low surface brightness galaxies in the IllustrisTNG\n simulation: We explore the nature of low surface brightness galaxies (LSBGs) in the\nhydrodynamic cosmological simulation TNG100 of the IllustrisTNG project,\nselecting a sample of LSBGs ($r$-band effective surface brightness $\\mu_r >\n22.0$ mag arcsec$^{-2}$) at $z=0$ over a wide range of stellar masses\n($M_{\\ast} = 10^{9}$-$10^{12}$ M$_\\odot$). We find LSBGs of all stellar masses,\nalthough they are particularly prevalent at $M_{\\ast} < 10^{10}$ M$_\\odot$. We\nshow that the specific star formation rates of LSBGs are not significantly\ndifferent from those of high surface brightness galaxies (HSBGs) but, as a\npopulation, LSBGs are systematically less massive and more extended than HSBGs,\nand tend to display late-type morphologies according to a kinematic criterion.\nAt fixed stellar mass, we find that haloes hosting LSBGs are systematically\nmore massive and have a higher baryonic fraction than those hosting HSBGs. We\nfind that LSBGs have higher stellar specific angular momentum and halo spin\nparameter values compared to HSBGs, as suggested by previous works. We track\nthe evolution of these quantities back in time, finding that the spin\nparameters of the haloes hosting LSBGs and HSBGs exhibit a clear bifurcation at\n$z \\sim 2$, which causes a similar separation in the evolutionary tracks of\nother properties such as galactic angular momentum and effective radius,\nultimately resulting in the values observed at $z =$ 0. The higher values of\nspecific stellar angular momentum and halo spin in LSBGs seem to be responsible\nfor their extended nature, preventing material from collapsing into the central\nregions of the galaxies, also causing LSBGs to host less massive black holes at\ntheir centres.", "positive": "Does the evolution of the radio luminosity function of star-forming\n galaxies match that of the star-formation rate function?: The assessment of the relationship between radio continuum luminosity and\nstar formation rate (SFR) is of crucial importance to make reliable predictions\nfor the forthcoming ultra-deep radio surveys and to allow a full exploitation\nof their results to measure the cosmic star formation history. We have\naddressed this issue by matching recent accurate determinations of the SFR\nfunction up to high redshifts with literature estimates of the 1.4 GHz\nluminosity functions of star forming galaxies (SFGs). This was done considering\ntwo options, proposed in the literature, for the relationship between the\nsynchrotron emission ($L_{\\rm synch}$), that dominates at 1.4 GHz, and the SFR:\na linear relation with a decline of the $L_{\\rm synch}$/SFR ratio at low\nluminosities or a mildly non-linear relation at all luminosities. In both cases\nwe get good agreement with the observed radio luminosity functions but, in the\nnon-linear case, the deviation from linearity must be small. The luminosity\nfunction data are consistent with a moderate increase of the $L_{\\rm\nsynch}$/SFR ratio with increasing redshift, indicated by other data sets,\nalthough a constant ratio cannot be ruled out. A stronger indication of such\nincrease is provided by recent deep 1.4 GHz counts, down to $\\mu$Jy levels.\nThis is in contradiction with models predicting a decrease of that ratio due to\ninverse Compton cooling of relativistic electrons at high redshifts.\nSynchrotron losses appear to dominate up to $z\\simeq 5$. We have also updated\nthe Massardi et al. (2010) evolutionary model for radio loud AGNs." }, { "anchor": "Delayed Massive-Star Mechanical Feedback at Low Metallicity: The classical model of massive-star mechanical feedback is based on effects\nat solar metallicity (Zsun), yet feedback parameters are very different at low\nmetallicity. Metal-poor stellar winds are much weaker, and more massive\nsupernova progenitors likely collapse directly to black holes without\nexploding. Thus, for ~0.4 Zsun we find reductions in the total integrated\nmechanical energy and momentum of ~40% and 75%, respectively, compared to\nvalues classically expected at solar metallicity. But in particular, these\nchanges effectively delay the onset of mechanical feedback until ages of ~10\nMyr. Feedback from high-mass X-ray binaries could slightly increase mechanical\nluminosity between ages 5-10 Myr, but it is stochastic and unlikely to be\nsignificant on this timescale. Stellar dynamical mechanisms remove most massive\nstars from clusters well before 10 Myr, which would further promote this\neffect; this process is exacerbated by gas retention implied by weak feedback.\nDelayed mechanical feedback implies that radiation feedback therefore dominates\nat early ages, which is consistent with the observed absence of superwinds in\nsome extreme starbursts. This scenario may lead to higher star-formation\nefficiencies, multiple stellar populations in clusters, and higher Lyman\ncontinuum escape. This could explain the giant star-forming complexes in\nmetal-poor galaxies and the small sizes of OB superbubble shells relative to\ntheir inferred ages. It could also drive modest effects on galactic chemical\nevolution, including on oxygen abundances. Thus, delayed low-metallicity\nmechanical feedback may have broad implications, including for early cosmic\nepochs.", "positive": "Magnetic fields in our Milky Way Galaxy and nearby galaxies: Magnetic fields in our Galaxy and nearby galaxies have been revealed by\nstarlight polarization, polarized emission from dust grains and clouds at\nmillimeter and submillimeter wavelength, the Zeeman effect of spectral lines or\nmaser lines from clouds or clumps, diffuse radio synchrotron emission from\nrelativistic electrons in interstellar magnetic fields, and the Faraday\nrotation of background radio sources as well as pulsars for our Milky Way. It\nis easy to get a global structure for magnetic fields in nearby galaxies, while\nwe have observed many details of magnetic fields in our Milky Way, especially\nby using pulsar rotation measure data. In general, magnetic fields in spiral\ngalaxies probably have a large-scale structure. The fields follow the spiral\narms with or without the field direction reversals. In the halo of spiral\ngalaxies magnetic fields exist and probably also have a large-scale structure\nas toroidal and poloidal fields, but seem to be slightly weaker than those in\nthe disk. In the central region of some galaxies, poloidal fields have been\ndetected as vertical components. Magnetic field directions in galaxies seem to\nhave been preserved during cloud formation and star formation, from large-scale\ndiffuse interstellar medium to molecular clouds and then to the cloud cores in\nstar formation regions or clumps for the maser spots. Magnetic fields in\ngalaxies are passive to dynamics." }, { "anchor": "The nature of [S III]\u03bb\u03bb9096, 9532 emitters at z = 1.34\n and 1.23: A study of [S III]$\\lambda\\lambda9096,9532$ emitters at $z$ = 1.34 and 1.23\nis presented using our deep narrow-band $H_2S1$ (centered at 2.13 $\\mu$m)\nimaging survey of the Extended Chandra Deep Field South (ECDFS). We combine our\ndata with multi-wavelength data of ECDFS to build up spectral energy\ndistributions (SEDs) from the $U$ to the $K_{s}$-band for emitter candidates\nselected with strong excess in $H_2S1 - K_{s}$ and derive photometric\nredshifts, line luminosities, stellar masses and extinction. A sample of 14 [S\nIII] emitters are identified with $H_2S1<22.8$ and $K_{\\rm s}<24.8$ (AB) over\n381 arcmin$^{2}$ area, having [S III] line luminosity $L_{[SIII]}= \\sim\n10^{41.5-42.6}$erg s$^{-1}$. None of the [S III] emitters is found to have\nX-ray counterpart in the deepest Chandra 4 Ms observation, suggesting that they\nare unlikely powered by AGN. HST/ACS F606W and HST/WFC3 F160W images show their\nrest-frame UV and optical morphologies. About half of the [S III] emitters are\nmergers and at least one third are disk-type galaxies. Nearly all [S III]\nemitters exhibit a prominent Balmer break in their SEDs, indicating the\npresence of a significant post-starburst component. Taken together, our results\nimply that both shock heating in post-starburst and photoionization caused by\nyoung massive stars are likely to excite strong [S III] emission lines. We\nconclude that the emitters in our sample are dominated by star-forming galaxies\nwith stellar mass $8.7<\\log (M/M_{sun})<9.9$.", "positive": "Chemical differentiation and gas kinematics around massive young stellar\n objects in RCW 120: We present results of a spectral survey towards a dense molecular\ncondensation and young stellar objects (YSOs) projected on the border of the\nHII region RCW 120 and discuss emission of 20 molecules which produce the\nbrightest lines. The survey was performed with the APEX telescope in the\nfrequency range 200 -- 260 GHz. We provide evidences for two outflows in the\ndense gas. The first one is powered by the RCW 120 S2 YSO and oriented along\nthe line of sight. The second outflow around RCW 120 S1 is aligned almost\nperpendicular to the line of sight. We show that area with bright emission of\nCH$_3$OH, CH$_3$CCH and CH$_3$CN are organised into an onion-like structure\nwhere CH$_3$CN traces warmer regions around the YSOs than the other molecules.\nMethanol seems to be released to the gas phase by shock waves in the vicinity\nof the outflows while thermal evaporation still does not work towards the YSOs.\nWe find only a single manifestation of the UV radiation to the molecules,\nnamely, enhanced abundances of small hydrocarbons CCH and c-C$_3$H$_2$ in the\nphoto-dissociation region." }, { "anchor": "FRBs Lensed by Point Masses II. The multi-peaked FRBs from the point\n view of microlensing: The microlensing effect has developed into a powerful technique for a diverse\nrange of applications including exoplanet discoveries, structure of the Milky\nWay, constraints on MAssive Compact Halo Objects, and measurements of the size\nand profile of quasar accretion discs. In this paper, we consider a special\ntype of microlensing events where the sources are fast radio bursts with\n$\\sim$milliseconds (ms) durations for which the relative motion between the\nlens and source is negligible. In this scenario, it is possible to temporally\nresolve the individual microimages. As a result, a method beyond the inverse\nray shooting (IRS) method, which only evaluates the total magnification of all\nmicroimages, is needed. We therefore implement an algorithm for identifying\nindividual microimages and computing their magnifications and relative time\ndelays. We validate our algorithm by comparing to analytical predictions for a\nsingle microlens case and find excellent agreement. We show that the\nsuperposition of pulses from individual microimages produces a light curve that\nappears as multi-peaked FRBs. The relative time delays between pulses can reach\n0.1--1 ms for stellar-mass lenses and hence can already be resolved temporally\nby current facilities. Although not yet discovered, microlensing of FRBs will\nbecome regular events and surpass the number of quasar microlensing events in\nthe near future when $10^{4-5}$ FRBs are expected to be discovered on a daily\nbasis. Our algorithm provides a way of generating the microlensing light curve\nthat can be used for constraining stellar mass distribution in distant\ngalaxies.", "positive": "Gathering dust: A galaxy-wide study of dust emission from cloud\n complexes in NGC 300: We used multi-band observations by the Herschel Space Observatory to study\nthe dust emission properties of the nearby spiral galaxy NGC 300. We compiled a\nfirst catalogue of the population of giant dust clouds (GDCs) in NGC 300 and\ngive an estimate of the total dust mass of the galaxy. We carried out source\ndetection with the multiwavelength source extraction algorithm getsources and\ncalculated physical properties of the GDCs, including mass and temperature,\nfrom five-band Herschel PACS and SPIRE observations from 100-500 $\\mu$m; the\nfinal size and mass estimates are based on the observations at 250 $\\mu$m that\nhave an effective spatial resolution of $\\sim$170 pc. We correlated our final\ncatalogue of GDCs to pre-existing catalogues of HII regions to infer the number\nof GDCs associated with high-mass star formation and determined the H$\\alpha$\nemission of the GDCs. Our final catalogue of GDCs includes 146 sources, 90 of\nwhich are associated with known HII regions. We find that the dust masses of\nthe GDCs are completely dominated by the cold dust component and range from\n$\\sim$1.1$\\cdot$10$^{3}$ - 1.4$\\cdot$10$^{4}$ M$_{\\odot}$. The GDCs have\neffective temperatures of $\\sim$13-23 K and show a distinct cold dust effective\ntemperature gradient from the centre towards the outer parts of the stellar\ndisk. We find that the population of GDCs in our catalogue constitutes\n$\\sim$16% of the total dust mass of NGC 300, which we estimate to be about\n5.4$\\cdot$10$^{6}$ M$_{\\odot}$. At least about 87% of our GDCs have a high\nenough average dust mass surface density to provide sufficient shielding to\nharbour molecular clouds. We compare our results to previous pointed molecular\ngas observations in NGC 300 and results from other nearby galaxies and also\nconclude that it is very likely that most of our GDCs are associated with\ncomplexes of giant molecular clouds." }, { "anchor": "The Chandra COSMOS Legacy Survey: Compton Thick AGN at high redshift: The existence of a large population of Compton thick (CT, $N_{H}>10^{24}\ncm^{-2}$) AGN is a key ingredient of most Cosmic X-ray background synthesis\nmodels. However, direct identification of these sources, especially at high\nredshift, is difficult due to the flux suppression and complex spectral shape\nproduced by CT obscuration. We explored the Chandra COSMOS Legacy point source\ncatalog, comprising 1855 sources, to select via X-ray spectroscopy, a large\nsample of CT candidates at high redshift. Adopting a physical model to\nreproduce the toroidal absorber, and a Monte-Carlo sampling method, we selected\n67 individual sources with >5% probability of being CT, in the redshift range\n$0.0410^{24} cm^{-2}$, gives\na total of 41.9 effective CT, corrected for classification bias. We derive\nnumber counts in the 2-10 keV band in three redshift bins. The observed\nlogN-logS is consistent with an increase of the intrinsic CT fraction\n($f_{CT}$) from $\\sim0.30$ to $\\sim0.55$ from low to high redshift. When\nrescaled to a common luminosity (log(L$_{\\rm X}$/erg/s)$=44.5$) we find an\nincrease from $f_{CT}=0.19_{-0.06}^{+0.07}$ to $f_{CT}=0.30_{-0.08}^{+0.10}$\nand $f_{CT}=0.49_{-0.11}^{+0.12}$ from low to high z. This evolution can be\nparametrized as $f_{CT}=0.11_{-0.04}^{+0.05}(1+z)^{1.11\\pm0.13}$. Thanks to\nHST-ACS deep imaging, we find that the fraction of CT AGN in\nmergers/interacting systems increases with luminosity and redshift and is\nsignificantly higher than for non-CT AGN hosts.", "positive": "Evolution of virial clouds-I: from surface of last scattering up to the\n formation of population-III stars: The analysis of WMAP and Planck CMB data has shown the presence of\ntemperature asymmetries towards the halos of several galaxies, which is\nprobably due to the rotation of clouds present in these halos about the\nrotational axis of the galaxies. It had been proposed that these are hydrogen\nclouds that {\\it should} be in equilibrium with the CMB. However, standard\ntheory did not allow equilibrium of such clouds at the very low CMB\ntemperature, but it was recently shown that the equilibrium {\\it could} be\nstable. This still does not prove that the cloud concentration and that the\nobserved temperature asymmetry is due to clouds in equilibrium with the CMB. To\ninvestigate the matter further, it would be necessary to trace the evolution of\nsuch clouds, which we call \"virial clouds\", from their formation epoch to the\npresent, so as to confront the model with the observational data. The task is\nto be done in two steps: (1) from the cloud formation before the formation of\nfirst generation of stars; (2) from that time to the present. In this paper we\ndeal with the first step leaving the second one to a subsequent analysis." }, { "anchor": "Evidence in favour of density wave theory through star formation history\n maps and spatially resolved stellar clusters: Stationary Density Wave Theory predicts the existence of an age gradient\nacross the spiral arms with a phase crossing at the co-rotation radius. Using\nstar formation history (SFH) maps of 12 nearby spiral galaxies derived from\n\\textsc{LIGHTNING} \\citep{Eufracio:2017}, a spectral energy distribution (SED)\nfitting procedure, and by using \\textsc{Spirality} \\citep{Shield:2015} a\n\\textsc{MATLAB}-based code which plots synthetic spiral arms over \\textsc{FITS}\nimages, we have found a gradual decrement in pitch angles with increasing age,\nthus providing us with evidence in favour of the Stationary Density Wave\nTheory. We have also used azimuthal offsets of spatially resolved stellar\nclusters in 3 LEGUS galaxies to observe age trends.", "positive": "Hubble Space Telescope Observations of Two Faint Dwarf Satellites of\n Nearby LMC Analogs from MADCASH: We present a deep Hubble Space Telescope (HST) imaging study of two dwarf\ngalaxies in the halos of Local Volume Large Magellanic Cloud (LMC) analogs.\nThese dwarfs were discovered as part of our Subaru+Hyper Suprime-Cam MADCASH\nsurvey: MADCASH-1, which is a satellite of NGC 2403 (D~3.2 Mpc), and MADCASH-2,\na previously unknown dwarf galaxy near NGC 4214 (D~3.0 Mpc). Our HST data reach\n>3.5 mag below the tip of the red giant branch (TRGB) of each dwarf, allowing\nus to derive their structural parameters and assess their stellar populations.\nWe measure TRGB distances ($D=3.41^{+0.24}_{-0.23}$ Mpc for MADCASH-1, and\n$D=3.00^{+0.13}_{-0.15}$ Mpc for MADCASH-2), and confirm their associations\nwith their host galaxies. MADCASH-1 is a predominantly old, metal-poor stellar\nsystem (age ~13.5 Gyr, [M/H] ~ -2.0), similar to many Local Group dwarfs.\nModelling of MADCASH-2's CMD suggests that it contains mostly ancient,\nmetal-poor stars (age ~13.5 Gyr, [M/H] ~ -2.0), but that ~10% of its stellar\nmass was formed 1.1--1.5 Gyr ago, and ~1% was formed 400--500 Myr ago. Given\nits recent star formation, we search MADCASH-2 for neutral hydrogen using the\nGreen Bank Telescope, but find no emission and estimate an upper limit on the\nHI mass of $<4.8\\times10^4 M_{\\odot}$. These are the faintest dwarf satellites\nknown around host galaxies of LMC mass outside the Local Group\n($M_{V,\\text{MADCASH-1}}=-7.81\\pm0.18$, $M_{V,\\text{MADCASH-2}}=-9.15\\pm0.12$),\nand one of them shows signs of recent environmental quenching by its host. Once\nthe MADCASH survey for faint dwarf satellites is complete, our census will\nenable us to test CDM predictions for hierarchical structure formation, and\ndiscover the physical mechanisms by which low-mass hosts influence the\nevolution of their satellites." }, { "anchor": "Hot magnetic halo of NGC628 (M74): In several spiral galaxies that are observed face-on, large-scale ordered\nmagnetic fields (the so-called magnetic arms) were found. One of the\nexplanations was the action of the magnetic reconnection, which leads to a\nhigher ordering of the magnetic fields. Because it simultaneously converts the\nenergy of the magnetic fields into thermal energy of the surroundings, magnetic\nreconnection has been considered as a heating mechanism of the interstellar\nmedium for many years. Until recently, no clear observational evidence for this\nphenomenon was found. We search for possible signatures of gas heating by\nmagnetic reconnection effects in the radio and X-ray data for the face-on\nspiral galaxy NGC628 (M74), which presents pronounced magnetic arms and\nevidence for vertical magnetic fields. The strengths and energy densities of\nthe magnetic field in the spiral and magnetic arms were derived, as were the\ntemperatures and thermal energy densities of the hot gas, for the disk and halo\nemission. In the regions of magnetic arms, higher order and lower energy\ndensity of the magnetic field is found than in the stellar spiral arms. The\nglobal temperature of the hot gas is roughly constant throughout the disk. The\ncomparison of the findings with those obtained for the starburst galaxy M83\nsuggests that magnetic reconnection heating may be present in the halo of\nNGC628. The joint analysis of the properties of the magnetic fields and the hot\ngas in NGC628 also provided clues for possible tidal interaction with the\ncompanion galaxy.", "positive": "X-ray Shadowing Experiments Toward Infrared Dark Clouds: We searched for X-ray shadowing toward two infrared dark clouds (IRDCs) using\nthe MOS detectors on XMM-Newton to learn about the Galactic distribution of\nX-ray emitting plasma. IRDCs make ideal X-ray shadowing targets of 3/4 kev\nphotons due to their high column densities, relatively large angular sizes, and\nknown kinematic distances. Here we focus on two clouds near 30 deg. Galactic\nlongitude at distances of 2 and 5 kpc from the Sun. We derive the foreground\nand background column densities of molecular and atomic gas in the direction of\nthe clouds. We find that the 3/4 kev emission must be distributed throughout\nthe Galactic disk. It is therefore linked to the structure of the cooler\nmaterial of the ISM, and to the birth of stars." }, { "anchor": "Stars behind bars II: A cosmological formation scenario for the Milky\n Way's central stellar structure: The stellar populations in the inner kiloparsecs of the Milky Way (MW) show\ncomplex kinematical and chemical structures. The origin and evolution of these\nstructures is still under debate. Here we study the central region of a fully\ncosmological hydrodynamical simulation of a disk galaxy that reproduces key\nproperties of the inner kiloparsecs of the MW: it has a boxy morphology and\nshows an overall rotation and dispersion profile in agreement with\nobservations. We use a clustering algorithm on stellar kinematics to identify a\nnumber of discrete kinematic components: a high- and low-spin disk, a stellar\nhalo and two bulge components; one fast rotating and one slow-rotating. We\nfocus on the two bulge components and show that the slow rotating one is\nspherically symmetric while the fast rotating component shows a boxy/peanut\nmorphology. Although the two bulge components are kinematically discrete\npopulations at present-day, they are both mostly formed over similar time\nscales, from disk material. We find that stellar particles with lower initial\nbirth angular momentum (most likely thick disc stars) end up in the\nslow-rotating low-spin bulge, while stars with higher birth angular momentum\n(most likely thin disc stars) are found in the high-spin bulge. This has the\nimportant consequence that a bulge population with a spheroidal morphology does\nnot necessarily indicate a merger origin. In fact, we do find that only\n$\\sim2.3$\\% of the stars in the bulge components are ex-situ stars brought in\nby accreted dwarf galaxies early on. We identify these ex-situ stars as the\noldest and most metal-poor stars on highly radial orbits with large vertical\nexcursions from the disk.", "positive": "Dissecting a 30 kpc galactic outflow at $z \\sim$ 1.7: We present the spatially resolved measurements of a cool galactic outflow in\nthe gravitationally lensed galaxy RCS0327 at $z \\approx 1.703$ using VLT/MUSE\nIFU observations. We probe the cool outflowing gas, traced by blueshifted Mg II\nand Fe II absorption lines, in 15 distinct regions of the same galaxy in its\nimage-plane. Different physical regions, 5 to 7 kpc apart within the galaxy,\ndrive the outflows at different velocities ($V_{out} \\sim $ $-161$ to $-240$ km\ns$^{-1}$), and mass outflow rates ($\\dot{M}_{out} \\sim$ 183 to 527 $M_{\\odot}\\\nyr^{-1}$). The outflow velocities from different regions of the same galaxy\nvary by 80 km s$^{-1}$, which is comparable to the variation seen in a large\nsample of star-burst galaxies in the local Universe. Using multiply lensed\nimages of RCS0327, we probe the same star-forming region at different spatial\nscales (0.5 kpc$^2$-25 kpc$^2$), we find that outflow velocities vary between $\n\\sim $ $-120$ to $-242$ km s$^{-1}$, and the mass outflow rates vary between\n$\\sim$ 37 to 254 $M_{\\odot}\\ yr^{-1}$. The outflow momentum flux in this galaxy\nis $\\geq$ 100% of the momentum flux provided by star-formation in individual\nregions, and outflow energy flux is $\\approx$ 10% of the total energy flux\nprovided by star-formation. These estimates suggest that the outflow in RCS0327\nis energy driven. This work shows the importance of small scale variations of\noutflow properties due to the variations of local stellar properties of the\nhost galaxy in the context of galaxy evolution." }, { "anchor": "Quasar emission lines as probes of orientation: implications for disc\n wind geometries and unification: The incidence of broad absorption lines (BALs) in quasar samples is often\ninterpreted in the context of a geometric unification model consisting of an\naccretion disc and an associated outflow. We use the the Sloan Digital Sky\nSurvey (SDSS) quasar sample to test this model by examining the equivalent\nwidths (EWs) of CIV 1550\\AA, Mg II 2800\\AA, [OIII] 5007\\AA\\ and C III] 1909\\AA.\nWe find that the emission line EW distributions in BAL and non-BAL quasars are\nremarkably similar -- a property that is inconsistent with scenarios in which a\nBAL outflow rises equatorially from a geometrically thin, optically thick\naccretion disc. We construct simple models to predict the distributions from\nvarious geometries; these models confirm the above finding and disfavour\nequatorial geometries. We show that obscuration, line anisotropy and general\nrelativistic effects on the disc continuum are unlikely to hide an EW\ninclination dependence. We carefully examine the radio and polarisation\nproperties of BAL quasars. Both suggest that they are most likely viewed (on\naverage) from intermediate inclinations, between type 1 and type 2 AGN. We also\nfind that the low-ionization BAL quasars in our sample are not confined to one\nregion of `Eigenvector I' parameter space. Overall, our work leads to one of\nthe following conclusions, or some combination thereof: (i) the continuum does\nnot emit like a geometrically thin, optically thick disc; (ii) BAL quasars are\nviewed from similar angles to non-BAL quasars, i.e. low inclinations; (iii)\ngeometric unification does not explain the fraction of BALs in quasar samples.", "positive": "Self-organization in Turbulent Molecular Clouds: Compressional versus\n Solenoidal Modes: We use three-dimensional numerical simulations to study self-organization in\nsupersonic turbulence in molecular clouds. Our numerical experiments describe\ndecaying and driven turbulent flows with an isothermal equation of state, sonic\nMach numbers from 2 to 10, and various degrees of magnetization. We focus on\nproperties of the velocity field and, specifically, on the level of its\npotential (dilatational) component as a function of turbulent Mach number,\nmagnetic field strength, and scale. We show how extreme choices of either\npurely solenoidal or purely potential forcing can reduce the extent of the\ninertial range in the context of periodic box models for molecular cloud\nturbulence. We suggest an optimized forcing to maximize the effective Reynolds\nnumber in numerical models." }, { "anchor": "Compact groups from semi-analytical models of galaxy formation -- V:\n their assembly channels as a function of the environment: We delved into the assembly pathways and environments of compact groups (CGs)\nof galaxies using mock catalogues generated from semi-analytical models (SAMs)\non the Millennium simulation. We investigate the ability of SAMs to replicate\nthe observed CG environments and whether CGs with different assembly histories\ntend to inhabit specific cosmic environments. We also analyse whether the\nenvironment or the assembly history is more important in tailoring CG\nproperties. We find that about half of the CGs in SAMs are non-embedded\nsystems, 40% are inhabiting loose groups or nodes of filaments, while the rest\ndistribute evenly in filaments and voids, in agreement with observations. We\nobserve that early-assembled CGs preferentially inhabit large galaxy systems (~\n60%), while around 30% remain non-embedded. Conversely, lately-formed CGs\nexhibit the opposite trend. We also obtain that lately-formed CGs have lower\nvelocity dispersions and larger crossing times than early-formed CGs, but\nmainly because they are preferentially non-embedded. Those lately-formed CGs\nthat inhabit large systems do not show the same features. Therefore, the\nenvironment plays a strong role in these properties for lately-formed CGs.\nEarly-formed CGs are more evolved, displaying larger velocity dispersions,\nshorter crossing times, and more dominant first-ranked galaxies, regardless of\nthe environment. Finally, the difference in brightness between the two\nbrightest members of CGs is dependent only on the assembly history and not on\nthe environment. CGs residing in diverse environments have undergone varied\nassembly processes, making them suitable for studying their evolution and the\ninterplay of nature and nurture on their traits.", "positive": "Masses of Isolated Spiral KIG Galaxies: We have updated the classification of late-type galaxies presented in the\nCatalog of Isolated Galaxies (KIG) using the advanced digital sky surveys. Our\nsearch for companions around 959 KIG galaxies revealed 141 neighbors associated\nwith 111 KIG galaxies within the mutual projection separation of less than 330\nkpc and the radial velocity difference not exceeding 500 km s$^{-1}$. Typical\nluminosity of the companions turned out to be weaker than the luminosity of the\nmain galaxies by more than an order of magnitude. Considering these small\ncompanions as test particles that move around the KIG galaxies along the\nKeplerian orbits with eccentricity of $e\\simeq0.7$, we estimated the total\n(orbital) masses of spiral KIG galaxies. Their average orbital mass-to-$K$-band\nluminosity ratio, $(20.9\\pm3.1) M_{\\odot}/L_{\\odot}$, is in a good agreement\nwith the corresponding value for the nearby Milky Way, M31 and M81-type massive\nspirals. Isolated disk-shaped galaxies have an on the average 2-3 times smaller\ntotal-mass-to-stellar-mass ratio than those of isolated bulge-shaped galaxies." }, { "anchor": "Galaxy and Mass Assembly (GAMA): Demonstrating the power of WISE in the\n study of Galaxy Groups to $z<0.1$: Combining high-fidelity group characterisation from the Galaxy and Mass\nAssembly (GAMA) survey and source-tailored $z<0.1$ photometry from the WISE\nsurvey, we present a comprehensive study of the properties of ungrouped\ngalaxies, compared to 497 galaxy groups (4$\\leq$ N$_{\\rm FoF}$ $\\leq$ 20) as a\nfunction of stellar and halo mass. Ungrouped galaxies are largely unimodal in\nWISE color, the result of being dominated by star-forming, late-type galaxies.\nGrouped galaxies, however, show a clear bimodality in WISE color, which\ncorrelates strongly with stellar mass and morphology. We find evidence for an\nincreasing early-type fraction, in stellar mass bins between\n$10^{10}\\lesssim$M$_{\\rm stellar} \\lesssim10^{11}$ M$_\\odot$, with increasing\nhalo mass. Using ungrouped, late-type galaxies with star-forming colors\n(W2$-$W3$>$3), we define a star-forming main-sequence (SFMS), which we use to\ndelineate systems that have moved below the sequence (\"quenched\" for the\npurposes of this work). We find that with increasing halo mass, the relative\nnumber of late-type systems on the SFMS decreases, with a corresponding\nincrease in early-type, quenched systems at high stellar mass (M$_{\\rm\nstellar}>{10}^{10.5}$ M$_\\odot$), consistent with mass quenching. Group\ngalaxies with masses M$_{\\rm stellar}<{10}^{10.5}$ M$_\\odot$ show evidence of\nquenching consistent with environmentally-driven processes. The stellar mass\ndistribution of late-type, quenched galaxies suggests they may be an\nintermediate population as systems transition from being star-forming and\nlate-type to the \"red sequence\". Finally, we use the projected area of groups\non the sky to extract groups that are (relatively) compact for their halo mass.\nAlthough these show a marginal increase in their proportion of high mass and\nearly-type galaxies compared to nominal groups, a clear increase in quenched\nfraction is not evident.", "positive": "Kinematics and Metallicities in the Bootes III Stellar Overdensity: a\n Disrupted Dwarf Galaxy?: We report the results of a spectroscopic study of the Bootes III (BooIII)\nstellar overdensity carried out with the Hectospec multifiber spectrograph on\nthe MMT telescope. Radial velocities have been measured for 193 BooIII\ncandidate stars selected to have magnitudes and colors consistent with its\nupper main sequence and lower red giant branch, as well as a number of\nhorizontal branch candidates. From 20 identified candidate BooIII members, we\nmeasure a systemic velocity of V_sun=197.5+-3.8 km/s and a velocity dispersion\nof sigma_o=14.0+-3.2 km/s. We use the somewhat large velocity dispersion and\nthe implied highly radial orbit, along with morphological evidence from\nGrillmair (2009) and stellar abundances, to argue that BooIII is likely the\nfirst known object observed in a transitional state between being a bound dwarf\ngalaxy and a completely unbound tidal stream." }, { "anchor": "Jeans Analysis for Dwarf Spheroidal Galaxies in Wave Dark Matter: Although still under debate, observations generally suggest that dwarf\nspheroidal (dSph) galaxies exhibit large constant-density cores in the centers,\nwhich can hardly be explained by dissipationless cold dark matter simulations\nwithout baryonic feedback. Wave dark matter (${\\psi {\\rm DM}}$), characterized\nby a single parameter, the dark matter particle mass $m_{\\psi}$, predicts a\ncentral soliton core in every galaxy arising from quantum pressure against\ngravity. Here we apply Jeans analysis assuming a soliton core profile to the\nkinematic data of eight classical dSphs so as to constrain $m_{\\psi}$, and\nobtain $m_{\\psi}=1.18_{-0.24}^{+0.28}\\times10^{-22}{\\,\\rm eV}$ and\n$m_{\\psi}=1.79_{-0.33}^{+0.35}\\times10^{-22}{\\,\\rm eV}~(2\\sigma)$ using the\nobservational data sets of Walker et al. (2007) and Walker et al. (2009b),\nrespectively. We show that the estimate of $m_{\\psi}$ is sensitive to the dSphs\nkinematic data sets and is robust to various models of stellar density profile.\nWe also consider multiple stellar subpopulations in dSphs and find consistent\nresults. This mass range of $m_{\\psi}$ is in good agreement with other\nindependent estimates, such as the high-redshift luminosity functions, the\nreionization history, and the Thomson optical depth to the cosmic microwave\nbackground.", "positive": "On the Survival of Cool Clouds in the Circum-Galactic Medium: We explore the survival of cool clouds in multi-phase circum-galactic media.\nWe revisit the \"cloud crushing problem\" in a large survey of simulations\nincluding radiative cooling, self-shielding, self-gravity, magnetic fields, and\nanisotropic Braginskii conduction and viscosity (with saturation). We explore a\nwide range of parameters including cloud size, velocity, ambient temperature\nand density, as well as a variety of magnetic field configurations and cloud\nturbulence. We find that realistic magnetic fields and turbulence have weaker\neffects on cloud survival; the most important physics is radiative cooling and\nconduction. Self-gravity and self-shielding are important for clouds which are\ninitially Jeans-unstable, but largely irrelevant otherwise.\nNon-self-gravitating, realistically magnetized clouds separate into four\nregimes: (1) At low column densities, clouds evaporate rapidly via conduction.\n(2) A \"failed pressure confinement\" regime, where the ambient hot gas cools too\nrapidly to provide pressure confinement for the cloud. (3) An \"infinitely\nlong-lived\" regime, in which the cloud lifetime becomes longer than the cooling\ntime of gas swept up in the leading bow shock, so the cloud begins to accrete\nand grow. (4) A \"classical cloud destruction\" regime, where clouds are\neventually destroyed by instabilities. In the final regime, the cloud lifetime\ncan exceed the naive cloud-crushing time owing to conduction-induced\ncompression. However, small and/or slow-moving clouds can also evaporate more\nrapidly than the cloud-crushing time. We develop simple analytic models that\nexplain the simulated cloud destruction times in this regime." }, { "anchor": "Complete element abundances of nine stars in the r-process galaxy\n Reticulum II: We present chemical abundances derived from high-resolution Magellan/MIKE\nspectra of the nine brightest known red giant members of the ultra-faint dwarf\ngalaxy Reticulum II. These stars span the full metallicity range of Ret II\n(-3.5 < [Fe/H] < -2). Seven of the nine stars have extremely high levels of\nr-process material ([Eu/Fe]~1.7), in contrast to the extremely low\nneutron-capture element abundances found in every other ultra-faint dwarf\ngalaxy studied to date. The other two stars are the most metal-poor stars in\nthe system ([Fe/H] < -3), and they have neutron-capture element abundance\nlimits similar to those in other ultra-faint dwarf galaxies. We confirm that\nthe relative abundances of Sr, Y, and Zr in these stars are similar to those\nfound in r-process halo stars but ~0.5 dex lower than the solar r-process\npattern. If the universal r-process pattern extends to those elements, the\nstars in Ret II display the least contaminated known r-process pattern. The\nabundances of lighter elements up to the iron peak are otherwise similar to\nabundances of stars in the halo and in other ultra-faint dwarf galaxies.\nHowever, the scatter in abundance ratios is large enough to suggest that\ninhomogeneous metal mixing is required to explain the chemical evolution of\nthis galaxy. The presence of low amounts of neutron-capture elements in other\nultra-faint dwarf galaxies may imply the existence of additional r-process\nsites besides the source of r-process elements in Ret II. Galaxies like Ret II\nmay be the original birth sites of r-process enhanced stars now found in the\nhalo.", "positive": "Criteria for gravitational instability and quasi-isolated gravitational\n collapse in turbulent medium: We study the evolution of structures in turbulent, self-gravitating media,\nand present an analytical criterion $M_{\\rm crit} \\approx \\epsilon_{\\rm\ncascade}^{2/3} \\eta^{-2/3} G^{-1} l^{5/3}$ (where $M_{\\rm crit}$ is the\ncritical mass, $l$ is the scale, $\\epsilon_{\\rm cascade}\\approx \\eta\n\\sigma_{\\rm v}^3 /l $ is the turbulence energy dissipation rate of the ambient\nmedium, $G$ is the gravitational constant, $\\sigma_{\\rm v}$ is the velocity\ndispersion, $l$ is the scale and $\\eta\\approx 0.2$ is an efficiency parameter)\nfor an object to undergo quasi-isolated gravitational collapse. The criterion\nalso defines the critical scale ($l_{\\rm crit} \\approx \\epsilon_{\\rm\ncascade}^{1/2} \\eta^{-1/2} G^{-3/4} \\rho^{-3/4}$) for turbulent gravitational\ninstability to develop. The analytical formalism explains the size dependence\nof the masses of the progenitors of star clusters ($M_{\\rm cluster} \\sim R_{\\rm\ncluster}^{1.67}$) in our Galaxy." }, { "anchor": "Little Red Dots: an abundant population of faint AGN at z~5 revealed by\n the EIGER and FRESCO JWST surveys: Characterising the prevalence and properties of faint active galactic nuclei\n(AGN) in the early Universe is key for understanding the formation of\nsupermassive black holes (SMBHs) and determining their role in cosmic\nreionization. We perform a spectroscopic search for broad H$\\alpha$ emitters at\n$z\\approx4-6$ using deep JWST/NIRCam imaging and wide field slitless\nspectroscopy from the EIGER and FRESCO surveys. We identify 20 H$\\alpha$ lines\nat $z=4.2-5.5$ that have broad components with line widths from $\\sim1200-3700$\nkm s$^{-1}$, contributing $\\sim30-90$ % of the total line flux. We interpret\nthese broad components as being powered by accretion onto SMBHs with implied\nmasses $\\sim10^{7-8}$ M$_{\\odot}$. In the UV luminosity range M$_{\\rm UV}=-21$\nto $-18$, we measure number densities of $\\approx10^{-5}$ cMpc$^{-3}$. This is\nan order of magnitude higher than expected from extrapolating quasar UV\nluminosity functions. Yet, such AGN are found in only $<1$ % of star-forming\ngalaxies at $z\\sim5$. The SMBH mass function agrees with large cosmological\nsimulations. In two objects we detect narrow red- and blue-shifted H$\\alpha$\nabsorption indicative, respectively, of dense gas fueling SMBH growth and\noutflows. We may be witnessing early AGN feedback that will clear dust-free\npathways through which more massive blue quasars are seen. We uncover a strong\ncorrelation between reddening and the fraction of total galaxy luminosity\narising from faint AGN. This implies that early SMBH growth is highly obscured\nand that faint AGN are only minor contributors to cosmic reionization.", "positive": "Primordial magnetic fields in Population III star formation: a\n magnetised resolution study: Population III stars form in groups due to the fragmentation of primordial\ngas. While uniform magnetic fields have been shown to support against\nfragmentation in present day star formation, it is unclear whether realistic\nk^3/2 primordial fields can have the same effect. We bypass the issues\nassociated with simulating the turbulent dynamo by introducing a saturated\nmagnetic field at equipartition with the velocity field when the central\ndensities reaches 10-13 g cm-3. We test a range of sink particle creation\ndensities from 10-10-10-8 g cm-3. Within the range tested, the fields did not\nsuppress fragmentation of the gas and hence could not prevent the degree of\nfragmentation from increasing with increased resolution. The number of sink\nparticles formed and total mass in sink particles was unaffected by the\nmagnetic field across all seed fields and resolutions. The magnetic pressure\nremained sub-dominant to the gas pressure except in the highest density regions\nof the simulation box, where it became equal to but never exceeded gas\npressure. Our results suggest that the inclusion of magnetic fields in\nnumerical simulations of Pop III star formation is largely unimportant." }, { "anchor": "Tracing the cosmic growth of super massive black holes to z ~ 3 with\n Herschel: We study a sample of Herschel-PACS selected galaxies within the GOODS-South\nand the COSMOS fields in the framework of the PACS Evolutionary Probe (PEP)\nproject. Starting from the rich multi-wavelength photometric data-sets\navailable in both fields, we perform a broad-band Spectral Energy Distribution\n(SED) decomposition to disentangle the possible active galactic nucleus (AGN)\ncontribution from that related to the host galaxy. We find that 37 per cent of\nthe Herschel-selected sample shows signatures of nuclear activity at the 99 per\ncent confidence level. The probability to reveal AGN activity increases for\nbright ($L_{\\rm 1-1000} > 10^{11} \\rm L_{\\odot}$) star-forming galaxies at\n$z>0.3$, becoming about 80 per cent for the brightest ($L_{\\rm 1-1000} >\n10^{12} \\rm L_{\\odot}$) infrared (IR) galaxies at $z \\geq 1$. Finally, we\nreconstruct the AGN bolometric luminosity function and the super-massive black\nhole growth rate across cosmic time up to $z \\sim 3$ from a Far-Infrared (FIR)\nperspective. This work shows general agreement with most of the panchromatic\nestimates from the literature, with the global black hole growth peaking at $z\n\\sim 2$ and reproducing the observed local black hole mass density with\nconsistent values of the radiative efficiency $\\epsilon_{\\rm rad}$\n($\\sim$0.07).", "positive": "Machine learning technique for morphological classification of galaxies\n from SDSS. II. The image-based morphological catalogs of galaxies at\n 0.02 10^6 solar mass and mass ratios > 1/4. Among these, the\nremnant galaxies characterized by the fastest formation of close,\ngravitationally bound MBHs have one or more of the following properties: (1)\nlarge stellar bulge, (2) comparable mass MBHs and (3) a galactic gas disk\nrotating close to the circular speed. In such galaxies, the MBHs with the\nshortest inspiral times, which are likely progenitors of coalescing MBHs, are\neither on circular prograde orbits or on very eccentric retrograde orbits. Our\nmodel also indicates that remnant galaxies with opposite properties, that host\nslowly evolving MBH pairs, are the most likely hosts of dual AGNs at kiloparsec\nseparations." }, { "anchor": "The Young Open Clusters King 12, NGC 7788, and NGC 7790: Pre-Main\n Sequence Stars and Extended Stellar Halos: The stellar contents of the open clusters King 12, NGC 7788, and NGC 7790 are\ninvestigated using MegaCam images. Comparisons with isochrones yield an age <\n20 Myr for King 12, 20--40 Myr for NGC 7788, and 60 -- 80 Myr for NGC 7790\nbased on the properties of stars near the main sequence turn-off (MSTO) in each\ncluster. The reddening of NGC 7788 is much larger than previously estimated.\nThe luminosity functions (LFs) of King 12 and NGC 7788 show breaks that are\nattributed to the onset of pre-main sequence (PMS) objects, and comparisons\nwith models of PMS evolution yield ages that are consistent with those measured\nfrom stars near the MSTO. In contrast, the r' LF of main sequence stars in NGC\n7790 is matched to r' = 20 by a model that is based on the solar neighborhood\nmass function. The structural properties of all three clusters are investigated\nby examining the two-point angular correlation function of blue main sequence\nstars. King 12 and NGC 7788 are each surrounded by a stellar halo that extends\nout to 5 arcmin (~ 3.4 parsecs) radius. It is suggested that these halos form\nin response to large-scale mass ejection early in the evolution of the\nclusters, as predicted by models. In contrast, blue main sequence stars in NGC\n7790 are traced out to a radius of ~ 7.5 arcmin, with no evidence of a halo. It\nis suggested that all three clusters may have originated in the same\nstar-forming complex, but not in the same giant molecular cloud.", "positive": "Dynamical population synthesis: Constructing the stellar single and\n binary contents of galactic field populations: [abridged] The galactic field's late-type stellar single and binary\npopulation is calculated on the supposition that all stars form as binaries in\nembedded star clusters. A recently developed tool (Marks, Kroupa & Oh) is used\nto evolve the binary star distributions in star clusters for a few Myr so that\na particular mixture of single and binary stars is achieved. On cluster\ndissolution the population enters the galactic field with these\ncharacteristics. The different contributions of single stars and binaries from\nindividual star clusters which are selected from a power-law embedded star\ncluster mass function are then added up. This gives rise to integrated galactic\nfield binary distribution functions (IGBDFs) resembling a galactic field's\nstellar content (Dynamical Population Synthesis). It is found that the binary\nproportion in the galactic field of a galaxy is larger the lower the minimum\ncluster mass, the lower the star formation rate, the steeper the embedded star\ncluster mass function and the larger the typical size of forming star clusters\nin the considered galaxy. In particular, period-, mass-ratio- and eccentricity\nIGBDFs for the Milky Way are modelled. The afore mentioned theoretical IGBDFs\nagree with independently observed distributions. Of all late-type binaries, 50%\nstem from M<300M_sun clusters, while 50% of all single stars were born in\nM>10^4M_sun clusters. Comparison of the G-dwarf and M-dwarf binary population\nindicates that the stars formed in mass-segregated clusters. In particular it\nis pointed out that although in the present model all M-dwarfs are born in\nbinary systems, in the Milky Way's Galactic field the majority ends up being\nsingle stars. This work predicts that today's binary frequency in elliptical\ngalaxies is lower than in spiral and in dwarf-galaxies. The period and\nmass-ratio distributions in these galaxies are explicitly predicted." }, { "anchor": "Infall of nearby galaxies into the Virgo cluster as traced with HST: We measured the Tip of the Red Giant Branch distances to nine galaxies in the\ndirection to the Virgo cluster using the Advanced Camera for Surveys on the\nHubble Space Telescope. These distances put seven galaxies: GR 34, UGC 7512,\nNGC 4517, IC 3583, NGC 4600, VCC 2037 and KDG 215 in front of the Virgo, and\ntwo galaxies: IC 3023, KDG 177 likely inside the cluster. Distances and radial\nvelocities of the galaxies situated between us and the Virgo core clearly\nexhibit the infall phenomenon toward the cluster. In the case of spherically\nsymmetric radial infall we estimate the radius of the \"zero-velocity surface\"\nto be (7.2+-0.7) Mpc that yields the total mass of the Virgo cluster to be\n(8.0+-2.3) X 10^{14} M_sun in good agreement with its virial mass estimates. We\nconclude that the Virgo outskirts does not contain significant amounts of dark\nmatter beyond its virial radius.", "positive": "Faint Submillimeter Galaxies Revealed by Multifield Deep ALMA\n Observations: Number Counts, Spatial Clustering, and A Dark Submillimeter\n Line Emitter: We present the statistics of faint submillimeter/millimeter galaxies (SMGs)\nand serendipitous detections of a submillimeter/millimeter line emitter (SLE)\nwith no multi-wavelength continuum counterpart revealed by the deep ALMA\nobservations. We identify faint SMGs with flux densities of 0.1-1.0 mJy in the\ndeep Band 6 and Band 7 maps of 10 independent fields that reduce cosmic\nvariance effects. The differential number counts at 1.2 mm are found to\nincrease with decreasing flux density down to 0.1 mJy. Our number counts\nindicate that the faint (0.1-1.0 mJy, or SFR_IR ~ 30-300 Msun/yr) SMGs\ncontribute nearly a half of the extragalactic background light (EBL), while the\nremaining half of the EBL is mostly contributed by very faint sources with flux\ndensities of <0.1 mJy (SFR_IR <~ 30 Msun/yr). We conduct counts-in-cells\nanalysis with the multifield ALMA data for the faint SMGs, and obtain a coarse\nestimate of galaxy bias, b_g <4. The galaxy bias suggests that the dark halo\nmasses of the faint SMGs are <~ 7x10^12 Msun, which is smaller than those of\nbright (>1 mJy) SMGs, but consistent with abundant high-z star-forming\npopulations such as sBzKs, LBGs, and LAEs. Finally, we report the serendipitous\ndetection of SLE-1 with continuum counterparts neither in our 1.2 mm-band nor\nmulti-wavelength images including ultra deep HST/WFC3 and Spitzer data. The SLE\nhas a significant line at 249.9 GHz with a signal-to-noise ratio of 7.1. If the\nSLE is not a spurious source made by unknown systematic noise of ALMA, the\nstrong upper limits of our multi-wavelength data suggest that the SLE would be\na faint galaxy at z >~ 6." }, { "anchor": "The hyperfine structure in the rotational spectrum of CF+: Context. CF+ has recently been detected in the Horsehead and Orion Bar\nphoto-dissociation regions. The J=1-0 line in the Horsehead is double-peaked in\ncontrast to other millimeter lines. The origin of this double-peak profile may\nbe kinematic or spectroscopic. Aims. We investigate the effect of hyperfine\ninteractions due to the fluorine nucleus in CF+ on the rotational transitions.\nMethods. We compute the fluorine spin rotation constant of CF+ using high-level\nquantum chemical methods and determine the relative positions and intensities\nof each hyperfine component. This information is used to fit the theoretical\nhyperfine components to the observed CF+ line profiles, thereby employing the\nhyperfine fitting method in GILDAS. Results. The fluorine spin rotation\nconstant of CF+ is 229.2 kHz. This way, the double-peaked CF+ line profiles are\nwell fitted by the hyperfine components predicted by the calculations. The\nunusually large hyperfine splitting of the CF+ line therefore explains the\nshape of the lines detected in the Horsehead nebula, without invoking intricate\nkinematics in the UV-illuminated gas.", "positive": "GMCs and their Type classification in M74: Toward understanding star\n formation and cloud evolution: We investigated the giant molecular clouds (GMCs) in M74 (NGC 628) obtained\nby the PHANGS project. We applied the GMC Types according to the activity of\nstar formation: Type I without star formation, Type II with H$\\alpha$\nluminosity ($L_{\\mathrm{H\\alpha}}$) smaller than $10^{37.5}\n\\mathrm{erg~s^{-1}}$, and Type III with $L_{\\mathrm{H\\alpha}}$ greater than\n$10^{37.5} \\mathrm{erg~s^{-1}}$. In total, 432 GMCs were identified, where the\nindividual GMC Types are 65, 203, and 164, for Type I, Type II, and Type III,\nrespectively. The size and mass of the GMCs range from 23 - 237 pc and\n$10^{4.9}$ - $10^{7.1}$ M$_{\\odot}$, showing a trend that mass and radius\nincrease from Type I to II to III. Clusters younger than 4 Myr and HII regions\nare found to be concentrated within 150 pc of a GMC, indicating a tight\nassociation of these young objects with the GMCs. The virial ratio tends to\ndecrease from Type I to III, indicating that Type III GMCs are most relaxed\ngravitationally among the three. We interpret that GMCs evolve from Type I to\nIII, as previously found in the LMC. The evolutionary timescales of the three\nTypes are estimated to be 2 Myr, 6 Myr, and 4 Myr, respectively, on a steady\nstate assumption, where we assume the timescale of Type III is equal to the age\nof the associated clusters, indicating a GMC lifetime of 12 Myr or longer.\nChevance et al. (2020) investigated GMCs using the same PHANGS dataset of M74,\nwhile these authors did not define a GMC, reaching an evolutionary picture with\na 20 Myr duration of the non-star forming phase, five times longer than 4 Myr.\nWe compare the present results with those by Chevance et al. (2020) and argue\nthat defining individual GMCs is essential to understanding GMC evolution." }, { "anchor": "Investigating the UV-excess in star clusters with $N$-body simulations:\n predictions for future CSST observations: We study the origin of the UV-excess in star clusters by performing N-body\nsimulations of six clusters with N=10k and N=100k (single stars & binary\nsystems) and metallicities of Z=0.01, 0.001, and 0.0001, using PETAR. All\nmodels initially have a 50 percent primordial binary fraction. Using GalevNB we\nconvert the simulated data into synthetic spectra and photometry for the China\nSpace Station Telescope (CSST) and Hubble Space Telescope (HST). From the\nspectral energy distributions we identify three stellar populations that\ncontribute to the UV-excess: (1) second asymptotic giant branch stars, which\ncontribute to the UV flux at early times; (2) naked helium stars, and (3) white\ndwarfs, which are long-term contributors to the FUV spectra. Binary stars\nconsisting of a white dwarf and a main-sequence star are cataclysmic variable\n(CV) candidates. The magnitude distribution of CV candidates is bimodal up to 2\nGyr. The bright CV population is particularly bright in FUV-NUV. The FUV-NUV\ncolor of our model clusters is 1-2 mag redder than the UV-excess globular\nclusters in M 87 and in the Milky Way. This discrepancy may be induced by\nhelium enrichment in observed clusters. Our simulations are based on simple\nstellar evolution; we do not include the effects of variations in helium and\nlight elements or multiple stellar populations. A positive radial color\ngradient is present in CSST NUV-y for main-sequence stars of all models with a\ncolor difference of 0.2-0.5 mag, up to 4 half-mass radii. The CSST NUV-g color\ncorrelates strongly with HST FUV-NUV for NUV-g>1 mag, with the linear relation\n$FUV-NUV=(1.09\\pm0.12)\\times(NUV-g)+(-1.01\\pm0.22)$. This allows for conversion\nof future CSST NUV-g colors into HST FUV-NUV colors, which are sensitive to\nUV-excess features. We find that CSST will be able to detect UV-excess in\ngalactic/extra-galactic star clusters with ages >200 Myr.", "positive": "Tracing extended low-velocity shocks through SiO emission - Case study\n of the W43-MM1 ridge: Previous literature suggests that the densest structures in the interstellar\nmedium form through colliding flows, but patent evidence of this process is\nstill missing. Recent literature proposes using SiO line emission to trace\nlow-velocity shocks associated with cloud formation through collision. In this\npaper we investigate the bright and extended SiO(2-1) emission observed along\nthe ~5 pc-long W43-MM1 ridge to determine its origin. We used high angular\nresolution images of the SiO(2-1) and HCN(1-0) emission lines obtained with the\nIRAM plateau de Bure (PdBI) interferometer and combined with data from the IRAM\n30 m radiotelescope. These data were complemented by a Herschel column density\nmap of the region. We performed spectral analysis of SiO and HCN emission line\nprofiles to identify protostellar outflows and spatially disentangle two\nvelocity components associated with low- and high-velocity shocks. Then, we\ncompared the low-velocity shock component to a dedicated grid of\none-dimensional (1D) radiative shock models. We find that the SiO emission\noriginates from a mixture of high-velocity shocks caused by bipolar outflows\nand low-velocity shocks. Using SiO and HCN emission lines, we extract seven\nbipolar outflows associated with massive dense cores previously identified\nwithin the W43-MM1 mini-starburst cluster. Comparing observations with\ndedicated Paris-Durham shock models constrains the velocity of the low-velocity\nshock component from 7 to 12km/s. The SiO arising from low-velocity shocks\nspreads along the complete length of the ridge. Its contribution represents at\nleast 45% and up to 100% of the total SiO emission depending on the area\nconsidered. The low-velocity component of SiO is most likely associated with\nthe ridge formation through colliding flows or cloud-cloud collision." }, { "anchor": "A comprehensive chemical abundance study of the outer halo globular\n cluster M 75: Context: M 75 is a relatively young Globular Cluster (GC) found at 15 kpc\nfrom the Galactic centre at the transition region between the inner and outer\nMilky Way halos. Aims: Our aims are to perform a comprehensive abundance study\nof a variety of chemical elements in this GC such as to investigate its\nchemical enrichment history in terms of early star formation, and to search for\nany multiple populations. Methods: We have obtained high resolution\nspectroscopy with the MIKE instrument at the Magellan telescope for 16 red\ngiant stars. Their membership within the GC is confirmed from radial velocity\nmeasurements. Our chemical abundance analysis is performed via equivalent width\nmeasurements and spectral synthesis, assuming local thermodynamic equilibrium\n(LTE). Results: We present the first comprehensive abundance study of M 75 to\ndate. The cluster is metal-rich ([Fe/H]=-1.16+/-0.02 dex,\n[alpha/Fe]=+0.30+/-0.02 dex), and shows a marginal spread in [Fe/H] of 0.07\ndex, typical of most GCs of similar luminosity. A moderately extended O-Na\nanticorrelation is clearly visible, likely showing three generations of stars,\nformed on a short timescale. Additionally the two most Na-rich stars are also\nBa-enhanced by 0.4 and 0.6 dex, respectively, indicative of pollution by lower\nmass (M ~ 4-5 M_Sun) Asymptotic Giant Branch (AGB) stars. The overall n-capture\nelement pattern is compatible with predominant r-process enrichment, which is\nrarely the case in GCs of such a high metallicity.", "positive": "Ionizing stellar population in the disk of NGC 3310 $-$ I. The impact of\n a minor merger on galaxy evolution: Numerical simulations of minor mergers predict little enhancement in the\nglobal star formation activity. However, it is still unclear the impact they\nhave on the chemical state of the whole galaxy and on the mass build-up in the\ngalaxy bulge and disc. We present a two-dimensional analysis of NCG 3310,\ncurrently undergoing an intense starburst likely caused by a recent minor\ninteraction, using data from the PPAK Integral Field Spectroscopy (IFS) Nearby\nGalaxies Survey (PINGS). With data from a large sample of about a hundred HII\nregions identified throughout the disc and spiral arms we derive, using\nstrong-line metallicity indicators and direct derivations, a rather flat\ngaseous abundance gradient. Thus, metal mixing processes occurred, as in\nobserved galaxy interactions. Spectra from PINGS data and additional\nmultiwavelength imaging were used to perform a spectral energy distribution\nfitting to the stellar emission and a photoionization modelling of the nebulae.\nThe ionizing stellar population is characterized by single populations with a\nnarrow age range (2.5-5 Myr) and a broad range of masses ($10^4-6\\times10^6\nM_\\odot$). The effect of dust grains in the nebulae is important, indicating\nthat 25-70% of the ultraviolet photons can be absorbed by dust. The ionizing\nstellar population within the HII regions represents typically a few percent of\nthe total stellar mass. This ratio, a proxy to the specific star formation\nrate, presents a flat or negative radial gradient. Therefore, minor\ninteractions may indeed play an important role in the mass build-up of the\nbulge." }, { "anchor": "The role of gas infall in the evolution of disc galaxies: Spiral galaxies are thought to acquire their gas through a protracted infall\nphase resulting in the inside-out growth of their associated discs. For field\nspirals, this infall occurs in the lower density environments of the cosmic\nweb. The overall infall rate, as well as the galactocentric radius at which\nthis infall is incorporated into the star-forming disc, plays a pivotal role in\nshaping the characteristics observed today. Indeed, characterising the\nfunctional form of this spatio-temporal infall in-situ is exceedingly\ndifficult, and one is forced to constrain these forms using the present day\nstate of galaxies with model or simulation predictions. We present the infall\nrates used as input to a grid of chemical evolution models spanning the mass\nspectrum of discs observed today. We provide a systematic comparison with\nalternate analytical infall schemes in the literature, including a first\ncomparison with cosmological simulations. Identifying the degeneracies\nassociated with the adopted infall rate prescriptions in galaxy models is an\nimportant step in the development of a consistent picture of disc galaxy\nformation and evolution.", "positive": "Deciphering the Origin of Ionized Gas in IC 1459 with VLT/MUSE: IC 1459 is an early-type galaxy (ETG) with a rapidly counter-rotating stellar\ncore, and is the central galaxy in a gas-rich group of spirals. In this work,\nwe investigate the abundant ionized gas in IC 1459 and present new stellar\norbital models to connect its complex array of observed properties and build a\nmore complete picture of its evolution. Using the Multi-Unit Spectroscopic\nExplorer (MUSE), the optical integral field unit (IFU) on the Very Large\nTelescope (VLT), we examine the gas and stellar properties of IC 1459 to\ndecipher the origin and powering mechanism of the galaxy's ionized gas. We\ndetect ionized gas in a non-disk-like structure rotating in the opposite sense\nto the central stars. Using emission-line flux ratios and velocity dispersion\nfrom full-spectral fitting, we find two kinematically distinct regions of\nshocked emission-line gas in IC 1459, which we distinguished using narrow\n($\\sigma$ $\\leq$ 155 km s$^{-1}$) and broad ($\\sigma$ $>$ 155 km s$^{-1}$)\nprofiles. Our results imply that the emission-line gas in IC 1459 has a\ndifferent origin than that of its counter-rotating stellar component. We\npropose that the ionized gas is from late-stage accretion of gas from the group\nenvironment, which occurred long after the formation of the central stellar\ncomponent. We find that shock heating and AGN activity are both ionizing\nmechanisms in IC 1459 but that the dominant excitation mechanism is by\npost-asymptotic giant branch stars from its old stellar population." }, { "anchor": "Tidally induced bars in dwarf galaxies on different orbits around a\n Milky Way-like host: Bars in galaxies may develop through a global instability or due to an\ninteraction with another system. We study bar formation in disky dwarf galaxies\norbiting a Milky Way-like galaxy. We employ $N$-body simulations to study the\nimpact of initial orbital parameters: the size of the dwarf galaxy orbit and\nthe inclination of its disc with respect to the orbital plane. In all cases a\nbar develops in the center of the dwarf during the first pericenter on its\norbit around the host. Between subsequent pericenter passages the bars are\nstable, but at the pericenters they are usually weakened and shortened. The\ninitial properties and details of the further evolution of the bars depend\nheavily on the orbital configuration. We find that for the exactly prograde\norientation, the strongest bar is formed for the intermediate-size orbit. On\nthe tighter orbit, the disc is too disturbed and stripped to form a strong bar.\nOn the wider orbit, the tidal interaction is too weak. The dependence on the\ndisc inclination is such that weaker bars form in more inclined discs. The bars\nexperience either a very weak buckling or none at all. We do not observe any\nsecular evolution, possibly because the dwarfs are perturbed at each pericenter\npassage. The rotation speed of the bars can be classified as slow\n($R_\\mathrm{CR}/l_\\mathrm{bar}\\sim2-3$). We attribute this to the loss of a\nsignificant fraction of the disc's rotation during the encounter with the host\ngalaxy.", "positive": "Spatially Extended NaI D Resonant Emission and Absorption in the\n Galactic Wind of the Nearby Infrared-Luminous Quasar F05189-2524: Emission from metal resonant lines has recently emerged as a potentially\npowerful probe of the structure of galactic winds at low and high redshift. In\nthis work, we present only the second example of spatially resolved\nobservations of NaI D emission from a galactic wind in a nearby galaxy (and the\nfirst 3D observations at any redshift). F05189-2524, a nearby (z=0.043) ultra\nluminous infrared galaxy powered by a quasar, was observed with the integral\nfield unit on the Gemini Multi-Object Spectrograph (GMOS) at Gemini North. NaI\nD absorption in the system traces dusty filaments on the near side of an\nextended, AGN-driven galactic wind (with projected velocities up to 2000 km/s).\nThese filaments (A_V < 4) and N(H) < 10^22 cm^-2) simultaneously obscure the\nstellar continuum and NaI D emission lines. The NaI D emission lines serve as a\ncomplementary probe of the wind; they are strongest in regions of low\nforeground obscuration and extend up to the limits of the field of view\n(galactocentric radii of 4 kpc). An azimuthally symmetric Sersic model\nextincted by the same foreground screen as the stellar continuum reproduces the\nNaI D emission line surface brightness distribution except in the inner regions\nof the wind, where some emission-line filling of absorption lines may occur.\nThe presence of detectable NaI D emission in F05189-2524 may be due to its high\ncontinuum surface brightness at the rest wavelength of NaI D. These data\nuniquely constrain current models of cool gas in galactic winds and serve as a\nbenchmark for future observations and models." }, { "anchor": "Eccentricity dynamics of wide binaries -- I. The effect of Galactic\n tides: A major puzzle concerning the wide stellar binaries (semimajor axes $a\\gtrsim\n10^3$\\,AU) in the Solar neighborhood is the origin of their observed\nsuperthermal eccentricity distribution function (DF), which is\nwell-approximated by $P(e)\\propto e^\\alpha$ with $\\alpha\\approx 1.3$. This DF\nevolves under the combined influence of (i) tidal torques from the Galactic\ndisk and (ii) scattering by passing stars, molecular clouds, and substructure.\nRecently, it was demonstrated that Galactic tides alone cannot produce a\nsuperthermal eccentricity DF from an initially isotropic, non-superthermal one,\nunder the restrictive assumptions that the eccentricity DF was initially of\npower law form and then was rapidly phase-mixed toward a steady state by the\ntidal perturbation. In this paper we first prove analytically that this\nconclusion is valid at all times, regardless of these assumptions. We then\nadopt a thin Galactic disk model and numerically integrate the equations of\nmotion for several ensembles of tidally perturbed wide binaries to study the\ntime evolution in detail. We find that even non-power law DFs can be described\nby an effective power law index $\\alpha_\\mathrm{eff}$ which accurately\ncharacterizes both their initial and final states, and that a DF with initial\n(effective or exact) power law index $\\alpha_\\mathrm{i}$ is transformed by\nGalactic tides into another power law with index $\\alpha_\\mathrm{f}\\approx\n(1+\\alpha_\\mathrm{i})/2$ on a timescale $ \\sim\n4\\,\\mathrm{Gyr}\\,(a/10^4\\mathrm{AU})^{-3/2}$. In a companion paper, we\ninvestigate separately the effect of stellar scattering. As the GAIA data\ncontinues to improve, these results will place strong constraints on wide\nbinary formation channels.", "positive": "New radial velocities for dwarf galaxies in the Local Volume: Radial velocities measured with the 6-meter telescope are given for 5 faint\ndwarf galaxies. All of these galaxies are confirmed as very nearby objects. Two\nof them, KK135 (dIr) and UGC 1703 (dSph/dTr), are local isolated dwarfs, and\nthe three others, UGCA 127sat (dIr), NGC 2683dw1 (dIr), and NGC891dwA (dTr),\nbelong to companions of nearby massive spirals." }, { "anchor": "Clustering Properties of Far-Infrared Sources in Hi-GAL Science\n Demonstration Phase Fields: We use a Minimum Spanning Tree algorithm to characterize the spatial\ndistribution of Galactic Far-IR sources and derive their clustering properties.\nWe aim to reveal the spatial imprint of different types of star forming\nprocesses, e.g. isolated spontaneous fragmentation of dense molecular clouds,\nor events of triggered star formation around HII regions, and highlight global\nproperties of star formation in the Galaxy. We plan to exploit the entire\nHi-GAL survey of the inner Galactic plane to gather significant statistics on\nthe clustering properties of star forming regions, and to look for possible\ncorrelations with source properties such as mass, temperature or evolutionary\nstage. In this paper we present a pilot study based on the two 2x2 square\ndegree fields centered at longitudes l=30 and l=59 obtained during the Science\nDemonstration Phase (SDP) of the Herschel mission. We find that over half of\nthe clustered sources are associated with HII regions and infrared dark clouds.\nOur analysis also reveals a smooth chromatic evolution of the spatial\ndistribution where sources detected at short-wavelengths, likely proto-stars\nsurrounded by warm circumstellar material emitting in the far-infrared, tend to\nbe clustered in dense and compact groups around HII regions while sources\ndetected at long-wavelengths, presumably cold and dusty density enhancements of\nthe ISM emitting in the sub-millimeter, are distributed in larger and looser\ngroups.", "positive": "IAU-FM6-- Angular momentum -- Conference summary: Angular momentum (AM) is a key parameter to understand galaxy formation and\nevolution. AM originates in tidal torques between proto-structures at turn\naround, and from this the specific AM is expected to scale as a power-law of\nslope 2/3 with mass. However, subsequent evolution re-shuffles this through\nmatter accretion from filaments, mergers, star formation and feedback, secular\nevolution and AM exchange between baryons and dark matter. Outer parts of\ngalaxies are essential to study since they retain most of the AM and the\ndiagnostics of the evolution. Galaxy IFU surveys have recently provided a\nwealth of kinematical information in the local universe. In the future, we can\nexpect more statistics in the outer parts, and evolution at high z, including\natomic gas with SKA." }, { "anchor": "The spatial distribution of an aromatic molecule, C6H5CN, in the cold\n dark cloud TMC-1: We present a highly sensitive 2D line survey of TMC-1 obtained with the Yebes\n40m radio telescope in the Q-band (31.13-49.53 GHz). These maps cover a region\nof 320 arcsec x 320 arcsec centred on the position of the QUIJOTE line survey\nwith a spatial sampling of 20 arcsec. The region covering 240 arcsec x 240\narcsec, where a longer integration time was used, shows a homogenous\nsensitivity of 2-4 mK across the band. We present in this work the first\ndetermination of the spatial extent of benzonitrile (C6H5CN), which follows\nthat of cyanopolyynes rather well, but differs significantly from that of the\nradicals CnH and CnN. We definitively conclude that aromatic species in TMC-1\nare formed from chemical reactions involving smaller species in the densest\nzones of the cloud.", "positive": "TRINITY IV: Predictions for Supermassive Black Holes at $z \\gtrsim 7$: We present predictions for the high-redshift halo-galaxy-supermassive black\nhole (SMBH) connection from the TRINITY model. Constrained by a comprehensive\ncompilation of galaxy ($0\\leq z \\leq 10$) and SMBH datasets ($0\\leq z \\leq\n6.5$), TRINITY finds: 1) The number of SMBHs with $M_\\bullet > 10^9 M_\\odot$ in\nthe observable Universe increases by six orders of magnitude from $z\\sim10$ to\n$z\\sim2$, and by another factor of $\\sim 3$ from $z\\sim2$ to $z=0$; 2) The\n$M_\\bullet > 10^9/10^{10} M_\\odot$ SMBHs at $z\\sim 6$ live in haloes with $\\sim\n(2-3)/(3-5) \\times 10^{12} M_\\odot$; 3) the new JWST AGNs at $7\\lesssim z\n\\lesssim 11$ are broadly consistent with the median SMBH mass-galaxy mass\nrelation for AGNs from TRINITY; 4) Seeds from runaway mergers in nuclear star\nclusters are viable progenitors for the SMBHs in GN-z11 ($z=10.6$) and\nCEERS_1019 ($z=8.7$); 5) $z=6-10$ quasar luminosity functions from wide area\nsurveys by, e.g., Roman and Euclid, will reduce uncertainties in the $z=6-10$\nSMBH mass-galaxy mass relation by up to $\\sim 0.5$ dex." }, { "anchor": "Protostellar classification using supervised machine learning algorithms: Classification of young stellar objects (YSOs) into different evolutionary\nstages helps us to understand the formation process of new stars and planetary\nsystems. Such classification has traditionally been based on spectral energy\ndistributions (SEDs). An alternative approach is provided by supervised machine\nlearning algorithms. We attempt to classify a sample of Orion YSOs into\ndifferent classes, where each source has already been classified using\nmultiwavelength SED analysis. We used 8 different learning algorithms to\nclassify the target YSOs, namely a decision tree, random forest, gradient\nboosting machine (GBM), logistic regression, na\\\"ive Bayes classifier,\n$k$-nearest neighbour classifier, support vector machine, and neural network.\nThe classifiers were trained and tested by using a 10-fold cross-validation\nprocedure. As the learning features, we employed ten continuum flux densities\nspanning from the near-IR to submm. With a classification accuracy of 82% (with\nrespect to the SED-based classes), a GBM algorithm was found to exhibit the\nbest performance. The lowest accuracy of 47% was obtained with a na\\\"ive Bayes\nclassifier. Our analysis suggests that the inclusion of the 3.6 $\\mu$m and 24\n$\\mu$m flux densities is useful to maximise the YSO classification accuracy.\nAlthough machine learning has the potential to provide a rapid and fairly\nreliable way to classify YSOs, an SED analysis is still needed to derive the\nphysical properties of the sources, and to create the labelled training data.\nThe classification accuracies can be improved with respect to the present\nresults by using larger data sets, more detailed missing value imputation, and\nadvanced ensemble methods. Overall, the application of machine learning is\nexpected to be very useful in the era of big astronomical data, for example to\nquickly assemble interesting target source samples for follow-up studies.", "positive": "Magnetic Fields in Massive Star-Forming Regions (MagMaR) I. Linear\n Polarized Imaging of the UCHII Region G5.89-0.39: We report 1.2 mm polarized continuum emission observations carried out with\nthe Atacama Large Millimeter/submillimeter Array (ALMA) toward the high-mass\nstar formation region G5.89-0.39. The observations show a prominent 0.2 pc\nnorth-south filamentary structure. The UCHII in G5.89-0.39 breaks the filament\nin two pieces. Its millimeter emission shows a dusty belt with a mass of 55-115\nM$_{\\odot}$ and 4,500 au in radius, surrounding an inner part comprising mostly\nionized gas with a dust emission only accounting about 30% of the total\nmillimeter emission. We also found a lattice of convex arches which may be\nproduced by dragged dust and gas from the explosive dispersal event involving\nthe O5 Feldt's star. The north-south filament has a mass between 300-600\nM$_{\\odot}$ and harbours a cluster of about 20 millimeter envelopes with a\nmedian size and mass of 1700 au and 1.5 M$_{\\odot}$, respectively, some of\nwhich are already forming protostars.\n We interpret the polarized emission in the filament as mainly coming from\nmagnetically aligned dust grains. The polarization fraction is ~4.4% in the\nfilaments and 2.1% at the shell. The magnetic fields are along the North\nFilament and perpendicular to the South Filament. In the Central Shell, the\nmagnetic fields are roughly radial in a ring surrounding the dusty belt between\n4,500 and 7,500 au, similar to the pattern recently found in the surroundings\nof Orion BN/KL. This may be an independent observational signpost of explosive\ndispersal outflows and should be further investigated in other regions." }, { "anchor": "Kelvin-Helmholtz Instability in Self-Gravitating Streams: Self-gravitating gaseous filaments exist on many astrophysical scales, from\nsub-pc filaments in the interstellar medium to Mpc scale streams feeding\ngalaxies from the cosmic web. These filaments are often subject to\nKelvin-Helmotz Instability (KHI) due to shearing against a confining background\nmedium. We study the nonlinear evolution of KHI in pressure-confined\nself-gravitating gas streams initially in hydrostatic equilibrium, using\nanalytic models and hydrodynamic simulations, not including radiative cooling.\nWe derive a critical line-mass as a function of the stream Mach number and\ndensity contrast with respect to the background, $\\mu_{cr}(M_b,\\delta_c)\\le 1$,\nwhere $\\mu=1$ is normalized to the maximal line mass for which initial\nhydrostatic equilibrium is possible. For $\\mu<\\mu_{cr}$, KHI dominates the\nstream evolution. A turbulent shear layer expands into the background and leads\nto stream deceleration at a similar rate to the non-gravitating case. However,\nwith gravity, penetration of the shear layer into the stream is halted at\nroughly half the initial stream radius by stabilizing buoyancy forces,\nsignificantly delaying total stream disruption. Streams with $\\mu_{cr}<\\mu\\le\n1$ fragment and form round, long-lived clumps by gravitational instability\n(GI), with typical separations roughly 8 times the stream radius, similar to\nthe case without KHI. When KHI is still somewhat effective, these clumps are\nbelow the spherical Jeans mass and are partially confined by external pressure,\nbut they approach the Jeans mass as $\\mu\\rightarrow 1$ and GI dominates. We\ndiscuss potential applications of our results to filaments in the ISM and dense\nstreams feeding galaxies at high redshift.", "positive": "The Metal Abundances across Cosmic Time ($\\mathcal{MACT}$) Survey. III\n -- The relationship between stellar mass and star formation rate in extremely\n low-mass galaxies: Extragalactic studies have demonstrated there is a moderately tight\n($\\approx$0.3 dex) relationship between galaxy stellar mass ($M_{\\star}$) and\nstar formation rate (SFR) that holds for star-forming galaxies at $M_{\\star}\n\\sim 3 \\times 10^8$-10$^{11}~M_{\\odot}$, i.e., the \"star formation main\nsequence.\" However, it has yet to be determined whether such a relationship\nextends to even lower mass galaxies, particularly at intermediate or higher\nredshifts. We present new results using observations for 714 narrowband\nH$\\alpha$-selected galaxies with stellar masses between $10^6$ and\n$10^{10}~M_{\\odot}$ (average of $10^{8.2}~M_{\\odot}$) at $z \\approx$ 0.07-0.5.\nThese galaxies have sensitive UV to near-infrared photometric measurements and\noptical spectroscopy. The latter allows us to correct our H$\\alpha$ SFRs for\ndust attenuation using Balmer decrements. Our study reveals: (1) for low-SFR\ngalaxies, our H$\\alpha$ SFRs systematically underpredict compared to FUV\nmeasurements, consistent with other studies; (2) at a given stellar mass\n($\\approx $10$ ^{8}~M_{\\odot}$), log(specific SFR) evolves as $ A \\log(1+z) $\nwith $ A = 5.26 \\pm 0.75 $, and on average, specific SFR increases with\ndecreasing stellar mass; (3) the SFR-$M_{\\star}$ relation holds for galaxies\ndown to $\\sim$10$^6~M_{\\odot}$ ($\\sim$1.5 dex below previous studies), and over\nlookback times of up to 5 Gyr, follows a redshift-dependent relation of\n$\\log{({\\rm SFR})} \\propto \\alpha \\log(M_{\\star}/M_{\\odot}) + \\beta z$ with\n$\\alpha = 0.60 \\pm 0.01$ and $\\beta = 1.86 \\pm 0.07$; and (4) the observed\ndispersion in the SFR-$M_{\\star}$ relation at low stellar masses is\n$\\approx$0.3 dex. Accounting for survey selection effects using simulated\ngalaxies, we estimate the true dispersion is $\\approx$0.5 dex." }, { "anchor": "Young Massive Clusters: Their Population Properties, Formation and\n Evolution, and Their Relation to the Ancient Globular Clusters: This review summarises the main properties of Young Massive Clusters (YMCs),\nincluding their population properties, particularly focusing on extragalactic\ncluster samples. We discuss potential biases and caveats that can affect the\nconstruction of cluster samples and how incompleteness effects can result in\nerroneous conclusions regarding the long term survival of clusters. In addition\nto the luminosity, mass and age distributions of the clusters, we discuss the\nsize distribution and profile evolution of the clusters. We also briefly\ndiscuss the stellar populations within YMCs. The final part of the review\nfocusses on the connections between YMCs and the ancient globular clusters,\nwhether or not they are related objects and how we can use what we know about\nYMC formation and evolution to understand how GCs formed in the early universe\nand how they relate to galaxy formation/evolution.", "positive": "The SAMI Galaxy Survey: Using concentrated star-formation and stellar\n population ages to understand environmental quenching: We study environmental quenching using the spatial distribution of current\nstar-formation and stellar population ages with the full SAMI Galaxy Survey. By\nusing a star-formation concentration index [C-index, defined as\nlog10(r_{50,Halpha}/r_{50,cont})], we separate our sample into regular galaxies\n(C-index>-0.2) and galaxies with centrally concentrated star-formation\n(SF-concentrated; C-index<-0.2). Concentrated star-formation is a potential\nindicator of galaxies currently undergoing `outside-in' quenching. Our\nenvironments cover ungrouped galaxies, low-mass groups (M_200<10^12.5 M_sun),\nhigh-mass groups (M_200 in the range 10^{12.5-14} M_sun) and clusters\n(M_200>10^14 M_sun). We find the fraction of SF-concentrated galaxies increases\nas halo mass increases with 9\\pm2 per cent, 8\\pm3 per cent, 19\\pm4 per cent and\n29\\pm4 per cent for ungrouped galaxies, low-mass groups, high-mass groups and\nclusters, respectively. We interpret these results as evidence for `outside-in'\nquenching in groups and clusters. To investigate the quenching time-scale in\nSF-concentrated galaxies, we calculate light-weighted age (Age_L) and\nmass-weighted age (Age_M) using full spectral fitting, as well as the Dn4000\nand Hdelta_A indices. We assume that the average galaxy age radial profile\nbefore entering a group or cluster is similar to ungrouped regular galaxies. At\nlarge radius (1-2 R_e), SF-concentrated galaxies in high-mass groups have older\nages than ungrouped regular galaxies with an age difference of 1.83\\pm0.38 Gyr\nfor Age_L and 1.34\\pm0.56 Gyr for Age_M. This suggests that while `outside-in'\nquenching can be effective in groups, the process will not quickly quench the\nentire galaxy. In contrast, the ages at 1-2 R_e of cluster SF-concentrated\ngalaxies and ungrouped regular galaxies are consistent (0.19\\pm0.21 Gyr for\nAge_L, 0.40\\pm0.61 Gyr for Age_M), suggesting the quenching process must be\nrapid." }, { "anchor": "Metal-Poor Stars and the Chemical Enrichment of the Universe: Metal-poor stars hold the key to our understanding of the origin of the\nelements and the chemical evolution of the Universe. This chapter describes the\nprocess of discovery of these rare stars, the manner in which their surface\nabundances (produced in supernovae and other evolved stars) are determined from\nthe analysis of their spectra, and the interpretation of their abundance\npatterns to elucidate questions of origin and evolution. More generally,\nstudies of these stars contribute to other fundamental areas that include\nnuclear astrophysics, conditions at the earliest times, the nature of the first\nstars, and the formation and evolution of galaxies -- including our own Milky\nWay. We illustrate this with results from studies of lithium formed during the\nBig Bang; of stars dated to within ~1 Gyr of that event; of the most metal-poor\nstars, with abundance signatures very different from all other stars; and of\nthe build-up of the elements over the first several Gyr. The combination of\nabundance and kinematic signatures constrains how the Milky Way formed, while\nrecent discoveries of extremely metal-poor stars in the Milky Way's dwarf\ngalaxy satellites constrain the hierarchical build-up of its stellar halo from\nsmall dark-matter dominated systems. [abridged]", "positive": "Mid-Infrared Outbursts in Nearby Galaxies: Nuclear Obscuration and\n Connections to Hidden Tidal Disruption Events and Changing-Look Active\n Galactic Nuclei: We study the properties of galaxies hosting mid-infrared outbursts in the\ncontext of a catalog of five hundred thousand galaxies from the Sloan Digital\nSky Survey. We find that nuclear obscuration, as inferred by the surrounding\ndust mass, does not correlate with host galaxy type, stellar properties (e.g.\ntotal mass and mean age), or with the extinction of the host galaxy as\nestimated by the Balmer decrement. This implies that nuclear obscuration may\nnot be able to explain any over-representation of tidal disruption events in\nparticular host galaxies. We identify a region in the galaxy catalog parameter\nspace that contains all unobscured tidal disruption events but only harbors\n$\\lesssim $ 11\\% of the mid-infrared outburst hosts. We find that mid-infrared\noutburst hosts appear more centrally concentrated and have higher galaxy\nS\\'ersic indices than galaxies hosting active galactic nuclei (AGN) selected\nusing the BPT classification. We thus conclude that the majority of\nmid-infrared outbursts are not hidden tidal disruption events but are instead\nconsistent with being obscured AGN that are highly variable, such as\nchanging-look AGN." }, { "anchor": "Age and Metallicity of galaxies in different environments of the Coma\n supercluster: We analyse luminosity-weighted ages and metallicity (Z) of galaxies in a\ncontinuous range of environments, i.e. clusters, filaments and voids prevalent\nin the Coma supercluster ($\\sim 100 h^{-1}$ Mpc). Specifically, we employ two\nabsorption line indices, H$\\beta$ and $\\langle\\rm{Fe}\\rangle$ as tracers of age\nand metallicity of galaxies. We find that the stellar-phase metallicity of\ngalaxies declines with increasing age as a function of stellar mass ($M^*$) as\nwell as environment. On the filaments, metallicity of galaxies varies as a\nfunction of their distance from the spine of the filament, such that galaxies\ncloser to the centre of the filaments have lower metallicity relative to their\ncounterparts 1 Mpc away from it. The mean age of intermediate mass galaxies\n($10^{10} < M^*/M_{\\odot} < 10^{10.5}$) galaxies is statistically significantly\ndifferent in different environments such that, the galaxies in clusters are\nolder than the filament galaxies by 1-1.5 Gyr, while their counterparts in the\nvoids are younger than filament galaxies by $\\sim 1$ Gyr. The massive galaxies\n($M^*/M_{\\odot} > 10^{10.5}$), on the other hand show no such difference for\nthe galaxies in clusters and filaments, but their counterparts in voids are\nfound to be younger by $\\sim 0.5$ Gyr. At fixed age however, Z of galaxies is\nindependent of their $M^*$ in all environments, except the most massive\n($M^*/M_{\\odot} \\gtrsim 10^{10.7}$), oldest galaxies ($\\gtrsim 9$ Gyr) which\nshow a sharp decline in their Z with $M^*$. Our results support a scenario\nwhere galaxies in the nearby Universe have grown by accreting smaller galaxies\nor primordial gas from the large-scale cosmic web.", "positive": "Optical photometry and basic parameters of 10 unstudied open clusters: We present BVI CCD photometry of 10 northern open clusters, Berkeley 43,\nBerkeley 45, Berkeley 47, NGC 6846, Berkeley 49, Berkeley 51, Berkeley 89,\nBerkeley 91, Tombaugh 4 and Berkeley 9, and estimate their fundamental\nparameters. Eight of the clusters are located in the first galactic quadrant\nand 2 are in the second. This is the first optical photometry for 8 clusters.\nAll of them are embedded in rich galactic fields and have large reddening\ntowards them (E(B-V) = 1.0 - 2.3 mag). There is a possibility that some of\nthese difficult-to-study clusters may be asterisms rather than physical\nsystems, but assuming they are physical clusters, we find that 8 of them are\nlocated beyond 2 kpc, and 6 clusters (60% of the sample) are located well above\nor below the Galactic plane. Seven clusters have ages 500 Myr or less and the\nother 3 are 1 Gyr or more in age. This sample of clusters has increased the\noptical photometry of clusters in the second half of the first galactic\nquadrant, beyond 2 kpc, from 10 to 15. NGC 6846 is found to be one of the most\ndistant clusters in this region of the Galaxy." }, { "anchor": "Variable Stars in Local Group Galaxies. I: Tracing the Early Chemical\n Enrichment and Radial Gradients in the Sculptor dSph with RR Lyrae Stars: We identified and characterized the largest (536) RR Lyrae (RRL) sample in a\nMilky Way dSph satellite (Sculptor) based on optical photometry data collected\nover $\\sim$24 years.\n The RRLs display a spread in V-magnitude ($\\sim$0.35 mag) which appears\nlarger than photometric errors and the horizontal branch (HB) luminosity\nevolution of a mono-metallic population. Using several calibrations of two\ndifferent reddening free and metal independent Period-Wesenheit relations we\nprovide a new distance estimate $\\mu$=19.62 mag ($\\sigma_{\\mu}$=0.04 mag) that\nagrees well with literature estimates. We constrained the metallicity\ndistribution of the old population, using the $M_I$ Period-Luminosity relation,\nand we found that it ranges from -2.3 to -1.5 dex. The current estimate is\nnarrower than suggested by low and intermediate spectroscopy of RGBs\n($\\Delta$[Fe/H] $\\le$ 1.5).\n We also investigated the HB morphology as a function of the galactocentric\ndistance. The HB in the innermost regions is dominated by red HB stars and by\nRRLs, consistent with a more metal-rich population, while in the outermost\nregions it is dominated by blue HB stars and RRLs typical of a metal-poor\npopulation. Our results suggest that fast chemical evolution occurred in\nSculptor, and that the radial gradients were in place at an early epoch.", "positive": "Using CO line ratios to trace the physical properties of molecular\n clouds: The carbon monoxide (CO) rotational transition lines are the most common\ntracers of molecular gas within giant molecular clouds (MCs). We study the\nratio ($R_{2-1/1-0}$) between CO's first two emission lines and examine what\ninformation it provides about the physical properties of the cloud. To study\n$R_{2-1/1-0}$ we perform smooth particle hydrodynamic simulations with time\ndependent chemistry (using GADGET-2), along with post-process radiative\ntransfer calculations on an adaptive grid (using RADMC-3D) to create synthetic\nemission maps of a MC. $R_{2-1/1-0}$ has a bimodal distribution that is a\nconsequence of the excitation properties of each line, given that $J=1$ reaches\nlocal thermal equilibrium (LTE) while $J=2$ is still sub-thermally excited in\nthe considered clouds. The bimodality of $R_{2-1/1-0}$ serves as a tracer of\nthe physical properties of different regions of the cloud and it helps\nconstrain local temperatures, densities and opacities. Additionally this\nbimodal structure shows an important portion of the CO emission comes from\ndiffuse regions of the cloud, suggesting that the commonly used conversion\nfactor of $R_{2-1/1-0}\\sim 0.7$ between both lines may need to be studied\nfurther." }, { "anchor": "The intracluster light on Frontier Fields clusters Abell 370 and Abell\n S1063: We analyzed the contribution of the intracluster light (ICL) to the total\nluminosity of two massive galaxy clusters observed by the Hubble Space\nTelescope within the Frontier Fields program, Abell 370 (z ~ 0.375) and Abell\nS1063 (z ~ 0.348), in order to correlate it with the dynamical stage of these\nsystems.We applied an algorithm based on the Chebyshev-Fourier functions called\nCICLE, specially developed to disentangle the ICL from the light of galaxies\nand measure the ICL fraction. We measured the ICL fraction in three broadband\noptical filters, F435W, F606W, and F814W, without assuming any prior hypothesis\nabout the ICL physical properties or morphology. The results obtained from the\nICL fraction vary between ~7% - 25%, and ~3% - 22% for both A370 and AS1063,\nrespectively, which are consistent with theoretical predictions for the total\namount of ICL obtained by ICL formation and evolution simulations.We found\nenhanced ICL fractions in the intermediate filter F606W for both clusters and\nwe suggest that this is due to the presence of an excess of\nyounger/lower-metallicity stars in the ICL compared to the cluster galaxies. We\nconclude that both Abell 370 and Abell S1063 are merging systems since they\nexhibit a similar feature as merging CLASH and Frontier Fields clusters\nsub-sample previously analyzed. We compare these results to the dynamical\nindicators obtained through different methods and we reinforce the use of ICL\nas a new and independent method to determine the dynamical state of clusters of\ngalaxies.", "positive": "NGC 7538 IRS2 in [NeII]: Shell and Cavity Kinematics of a Compact HII\n Region: NGC 7538 IRS2 is a compact HII region and recent star formation source, with\na shell morphology, lying on the border of the visible HII region NGC 7538. We\npresent a spectral cube of the [NeII] 12.8 micron emission line obtained with\nthe TEXES spectrometer on Gemini North with velocity resolution approximately 4\nkm/s and angular resolution 0.3\". The kinematics of the data cube show ionized\ngas flowing along multiple cavity walls. We have simulated the kinematics and\nstructure of IRS2 with a model of superimposed cavities created by outflows\nfrom embedded stars in a cloud with density gradients. Most of the cavities,\nincluding the largest that dominates IRS2 structure, are associated with B-type\nstars; the outflow of the bright ionizing O star binary IRS2a/b is small in\nextent and lies in a high-density clump. The IRS2 model shows that the behavior\nof an HII region is not a matter of only the most massive star present; cloud\nclumpiness and activity of lower mass stars may determine the structure and\nkinematics." }, { "anchor": "Optically selected fossil groups; X-ray observations and galaxy\n properties: We report on the X-ray and optical observations of galaxy groups selected\nfrom the 2dfGRS group catalog, to explore the possibility that galaxy groups\nhosting a giant elliptical galaxy and a large optical luminosity gap present\nbetween the two brightest group galaxies, can be associated with an extended\nX-ray emission, similar to that observed in fossil galaxy groups. The X-ray\nobservations of 4 galaxy groups were carried out with Chandra telescope with\n10-20 ksec exposure time. Combining the X-ray and the optical observations we\nfind evidences for the presence of a diffuse extended X-ray emission beyond the\noptical size of the brightest group galaxy. Taking both the X-ray and the\noptical criteria, one of the groups is identified as a fossil group and one is\nruled out because of the contamination in the earlier optical selection. For\nthe two remaining systems, the X-ay luminosity threshold is close to the\nconvention know for fossil groups. In all cases the X-ray luminosity is below\nthe expected value from the X-ray selected fossils for a given optical\nluminosity of the group. A rough estimation for the comoving number density of\nfossil groups is obtained and found to be in broad agreement with the\nestimations from observations of X-ray selected fossils and predictions of\ncosmological simulations.", "positive": "The Pan-STARRS1 z>5.6 quasar survey II: Discovery of 55 Quasars at\n 5.66 enables detailed studies of\nsupermassive black holes, massive galaxies, structure formation, and the state\nof the intergalactic medium within the first billion years after the Big Bang.\nWe present the spectroscopic confirmation of 55 quasars at redshifts 5.6 10 exp(11) cm^(-3) at the\ncenter of the accretion disk. IRAS23226-3843 shows unusually strong FeII blends\nwith respect to the broad line widths, in contrast to what is known from\nEigenvector 1 studies.", "positive": "The Effects of $\u039b$CDM Dark Matter Substructure on the Orbital\n Evolution of Star Clusters: We present a comprehensive study on how perturbations due to a distribution\nof $\\Lambda$CDM dark matter subhalos can lead to star clusters deviating from\ntheir orbits. Through a large suite of massless test particle simulations, we\nfind that (1) subhalos with masses less than $10^8 M_{\\odot}$ negligibly affect\ntest particle orbits, (2) perturbations lead to orbital deviations only in\nenvironments with substructure fractions $f_{sub} \\geq 1\\%$, (3) perturbations\nfrom denser subhalos produce larger orbital deviations, and (4) subhalo\nperturbations that are strong relative to the background tidal field lead to\nlarger orbital deviations. To predict how the variation in test particle\norbital energy $\\sigma_e(t)$ increases with time, we test the applicability of\ntheory derived from single-mass subhalo populations to populations where\nsubhalos have a mass spectrum. We find $\\sigma_e(t)$ can be predicted for test\nparticle evolution within a mass spectrum of subhalos by assuming subhalos all\nhave masses equal to the mean subhalo mass and by using the local mean subhalo\nseparation to estimate the change in test particle velocities due to subhalo\ninteractions. Furthermore, the orbital distance variation at an orbital\ndistance $r$ can be calculated via $\\sigma_r=2.98 \\times 10^{-5} \\pm 8 \\times\n10^{-8} (\\rm kpc^{-1} km^{-2} s^{2}) \\times r \\times \\sigma_e$ with a\ndispersion about the line of best fit equalling 0.08 kpc. Finally, we conclude\nthat clusters that orbit within 100 kpc of Milky Way-like galaxies experience a\nchange no greater than $2\\%$ in their dissolution times." }, { "anchor": "The stellar population responsible for a kiloparsec size superbubble\n seen in the JWST \"phantom\" images of NGC628: We here study the multi-band properties of a kiloparsec-size superbubble in\nthe late-type spiral galaxy NGC628. The superbubble is the largest of many\nholes seen in the early release images using JWST/MIRI filters that trace the\nPolycyclic Aromatic Hydrocarbon (PAH) emissions. The superbubble is located in\nthe interarm region ~3 kpc from the galactic center in the south-east\ndirection. The shell surrounding the superbubble is detected in HI, CO, and\nHalpha with an expansion velocity of 12 km/s, and contains as much as 2x10^7\nMsun of mass in gas that is mostly in molecular form. We find a clear excess of\nblue, bright stars inside the bubble as compared to the surrounding disk on the\nHST/ACS images. These excess blue, bright stars are part of a stellar\npopulation of 10^5 Msun mass that is formed over the last 50 Myr in different\nstar formation episodes, as determined from an analysis of color-magnitude\ndiagrams using a Bayesian technique. The mechanical power injected by the\nmassive stars of these populations is sufficient to provide the energy\nnecessary for the expansion of the shell gas. Slow and steady, rather than\nviolent, injection of energy is probably the reason for the maintenance of the\nshell structure over the kiloparsec scale. The expanding shell is currently the\nsite for triggered star formation as inferred from the JWST 21 micron (F2100W\nfilter) and the Halpha images.", "positive": "Learning algorithms at the service of WISE survey: We have undertaken a dedicated program of automatic source classification in\nthe WISE database merged with SuperCOSMOS scans, comprehensively identifying\ngalaxies, quasars and stars on most of the unconfused sky. We use the Support\nVector Machines classifier for that purpose, trained on SDSS spectroscopic\ndata. The classification has been applied to a photometric dataset based on\nall-sky WISE 3.4 and 4.6 $\\mu$m information cross-matched with SuperCOSMOS B\nand R bands, which provides a reliable sample of $\\sim170$ million sources,\nincluding galaxies at $z_{\\rm med}\\sim0.2$, as well as quasars and stars. The\nresults of our classification method show very high purity and completeness\n(more than 96\\%) of the separated sources, and the resultant catalogs can be\nused for sophisticated analyses, such as generating all-sky photometric\nredshifts." }, { "anchor": "An Estimate of the Binary Star Fraction Among Young Stars at the\n Galactic Center: Possible Evidence of a Radial Dependence: We present the first estimate of the intrinsic binary fraction of young stars\nacross the central $\\approx$ 0.4 pc surrounding the supermassive black hole\n(SMBH) at the Milky Way Galactic center (GC). This experiment searched for\nphotometric variability in 102 young stars, using 119 nights of 10\"-wide\nadaptive optics imaging observations taken at Keck Observatory over 16 years in\nthe K'- and H-bands. We photometrically detected three binary stars, all of\nwhich are situated more than 1\" (0.04 pc) from the SMBH and one of which,\nS2-36, is newly reported here with spectroscopic confirmation. To convert the\nobserved binary fraction into an estimate of the underlying binary fraction, we\ndetermined experiment sensitivity through detailed light curve simulations,\nincorporating photometric effects of eclipses, irradiation, and tidal\ndistortion in binaries. The simulations assumed a population of young binaries,\nwith stellar ages (4 Myr) and masses matched to the most probable values\nmeasured for the GC young star population and underlying binary system\nparameters similar to those of local massive stars. The detections and\nsimulations imply young, massive stars in the GC have a stellar binary fraction\n$\\geq$ 71% (68% confidence), or $\\geq$ 42% (95% confidence). This inferred GC\nyoung star binary fraction is consistent with that typically seen in young\nstellar populations in the solar neighborhood. Furthermore, our measured binary\nfraction is significantly higher than that recently reported by Chu et al.\n(2023) based on RV measurements of young stars <~1\" of the SMBH. Constrained\nwith these two studies, the probability that the same underlying young binary\nfraction extends across the entire region is <1.4%. This tension provides\nsupport for a radial dependence of the binary star fraction and, therefore, for\nthe dynamical predictions of binary merger and evaporation events close to the\nSMBH.", "positive": "Ionized outflows from active galactic nuclei as the essential elements\n of feedback: Outflows from active galactic nuclei (AGN) are one of the fundamental\nmechanisms by which the central supermassive black hole interacts with its host\ngalaxy. Detected in $\\ge 50\\%$ of nearby AGN, these outflows have been found to\ncarry kinetic energy that is a significant fraction of AGN power, and thereby\ngive negative feedback to their host galaxies. To understand the physical\nprocesses that regulate them, it is important to have a robust estimate of\ntheir physical and dynamical parameters. In this review we summarize our\ncurrent understanding on the physics of the ionized outflows detected in\nabsorption in the UV and X-ray wavelength bands. We discuss the most relevant\nobservations and our current knowledge and uncertainties in the measurements of\nthe outflow parameters. We also discuss their origin and acceleration\nmechanisms. The commissioning and concept studies of large telescope missions\nwith high resolution spectrographs in UV/optical and X-rays along with rapid\nadvancements in simulations offer great promise for discoveries in this field\nover the next decade." }, { "anchor": "Measuring filament orientation: a new quantitative, local approach: The relative orientation between filamentary structures in molecular clouds\nand the ambient magnetic field provides insight into filament formation and\nstability. To calculate the relative orientation, a measurement of filament\norientation is first required. We propose a new method to calculate the\norientation of the one pixel wide filament skeleton that is output by filament\nidentification algorithms such as \\textsc{filfinder}. We derive the local\nfilament orientation from the direction of the intensity gradient in the\nskeleton image using the Sobel filter and a few simple post-processing steps.\nWe call this the `Sobel-gradient method'. The resulting filament orientation\nmap can be compared quantitatively on a local scale with the magnetic field\norientation map to then find the relative orientation of the filament with\nrespect to the magnetic field at each point along the filament. It can also be\nused in constructing radial profiles for filament width fitting. The proposed\nmethod facilitates automation in analysis of filament skeletons, which is\nimperative in this era of `big data'.", "positive": "Continuum polarization reverberation mapping of AGNs: The determination of the size and geometry of the broad line region (BLR) in\nactive galactic nuclei is one of the major ingredients for determining the mass\nof the accreting black hole. This can be done by determining the delay between\nthe optical continuum and the flux reprocessed by the BLR, in particular via\nthe emission lines. We propose here that the delay between polarized and\nunpolarized light can also be used in much the same way to constrain the size\nof the BLR; we check that meaningful results can be expected from observations\nusing this technique. We use our code STOKES for performing polarized radiative\ntransfer simulations. We determine the response of the central source\nenvironment (broad line region, dust torus, polar wind) to fluctuations of the\ncentral source that are randomly generated; we then calculate the cross\ncorrelation between the simulated polarized flux and the total flux to estimate\nthe time delay that would be provided by observations using the same method. We\nfind that the broad line region is the main contributor to the delay between\nthe polarized flux and the total flux; this delay is independent on the\nobservation wavelength. This validates the use of polarized radiation in the\noptical/UV band to estimate the geometrical properties of the broad line region\nin type I AGNs, in which the viewing angle is close to pole-on and the BLR is\nnot obscured by the dust torus." }, { "anchor": "Astrometry of H$_{2}$O Masers in Nearby Star-Forming Regions with VERA\n --- IV. L1448C: We have carried out multi-epoch VLBI observations with VERA (VLBI Exploration\nof Radio Astrometry) of the 22~GHz H$_{2}$O masers associated with a Class 0\nprotostar L1448C in the Perseus molecular cloud. The maser features trace the\nbase of collimated bipolar jet driven by one of the infrared counter parts of\nL1448C named as L1448C(N) or L1448-mm A. We detected possible evidences for\napparent acceleration and precession of the jet according to the\nthree-dimensional velocity structure. Based on the phase-referencing VLBI\nastrometry, we have successfully detected an annual parallax of the H$_{2}$O\nmaser in L1448C to be 4.31$\\pm$0.33~milliarcseconds (mas) which corresponds to\na distance of 232$\\pm$18~pc from the Sun. The present result is in good\nagreement with that of another H$_{2}$O maser source NGC~1333 SVS13A in the\nPerseus molecular cloud, 235~pc. It is also consistent with the photometric\ndistance, 220~pc. Thus, the distance to the western part of the Perseus\nmolecular cloud complex would be constrained to be about 235~pc rather than the\nlarger value, 300~pc, previously reported.", "positive": "Faraday Rotation from Magnesium II Absorbers towards Polarized\n Background Radio Sources: Strong singly-ionized magnesium (MgII) absorption lines in quasar spectra\ntypically serve as a proxy for intervening galaxies along the line of sight.\nPrevious studies have found a correlation between the number of these MgII\nabsorbers and the Faraday rotation measure (RM) at $\\approx5$ GHz. We\ncross-match a sample of 35,752 optically-identified non-intrinsic MgII\nabsorption systems with 25,649 polarized background radio sources for which we\nhave measurements of both the spectral index and RM at 1.4 GHz. We use the\nspectral index to split the resulting sample of 599 sources into flat-spectrum\nand steep-spectrum subsamples. We find that our flat-spectrum sample shows\nsignificant ($\\sim3.5\\sigma$) evidence for a correlation between MgII\nabsorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such\ncorrelation. We argue that such an effect cannot be explained by either\nluminosity or other observational effects, by evolution in another confounding\nvariable, by wavelength-dependent polarization structure in an active galactic\nnucleus, by the Galactic foreground, by cosmological expansion, or by partial\ncoverage models. We conclude that our data are most consistent with intervenors\ndirectly contributing to the Faraday rotation along the line of sight, and that\nthe intervening systems must therefore have coherent magnetic fields of\nsubstantial strength ($\\bar{B}=1.8\\pm0.4$ $\\mu$G). Nevertheless, the weak\nnature of the correlation will require future high-resolution and broadband\nradio observations in order to place it on a much firmer statistical footing." }, { "anchor": "The Turbulence Power Spectrum in Optically Thick Interstellar Clouds: The Fourier power spectrum is one of the most widely used statistical tools\nto analyze the nature of magnetohydrodynamic turbulence in the interstellar\nmedium. Lazarian & Pogosyan (2004) predicted that the spectral slope should\nsaturate to -3 for an optically thick medium and many observations exist in\nsupport of their prediction. However, there have not been any numerical studies\nto-date testing these results. We analyze the spatial power spectrum of MHD\nsimulations with a wide range of sonic and Alfv\\'enic Mach numbers, which\ninclude radiative transfer effects of the $^{13}$CO transition. We confirm\nnumerically the predictions of Lazarian & Pogosyan (2004) that the spectral\nslope of line intensity maps of an optically thick medium saturates to -3.\nFurthermore, for very optically thin supersonic CO gas, where the density or CO\nabundance values are too low to excite emission in all but the densest shock\ncompressed gas, we find that the spectral slope is shallower than expected from\nthe column density. Finally, we find that mixed optically thin/thick CO gas,\nwhich has average optical depths on order of unity, shows mixed behavior: for\nsuper-Alfv\\'enic turbulence, the integrated intensity power spectral slopes\ngenerally follow the same trend with sonic Mach number as the true column\ndensity power spectrum slopes. However, for sub-Alfv\\'enic turbulence the\nspectral slopes are steeper with values near -3 which are similar to the very\noptically thick regime.", "positive": "The Galactic thin and thick discs in the context of galaxy formation: We have obtained high-resolution spectra and carried out a detailed elemental\nabundance analysis for a new sample of 899 F and G dwarf stars in the Solar\nneighbourhood. The results allow us to, in a multi-dimensional space consisting\nof stellar ages, detailed elemental abundances, and full kinematic information\nfor the stars, study and trace their respective origins. Here we briefly\naddress selection criteria and discuss how to define a thick disc star. The\nresults are discussed in the context of galaxy formation." }, { "anchor": "Generalised transport equation of the Autocovariance Function of the\n density field and mass invariant in star-forming clouds: In this Letter, we study the evolution of the autocovariance function (ACF)\nof density field fluctuations in star-forming clouds and thus of the\ncorrelation length $l_c(\\rho)$ of these fluctuations, which can be identified\nas the average size of the most correlated structures within the cloud.\nGeneralizing the transport equation derived by Chandrasekhar (1951) for static,\nhomogeneous turbulence, we show that the mass contained within these structures\nis an invariant, i.e. that the average mass contained in the most correlated\nstructures remains constant during the evolution of the cloud, whatever\ndominates the global dynamics (gravity or turbulence).\n We show that the growing impact of gravity on the turbulent flow yields an\nincrease of the variance of the density fluctuations and thus a drastic\ndecrease of the correlation length. Theoretical relations are successfully\ncompared to numerical simulations. This picture brings a robust support to star\nformation paradigms where the mass concentration in turbulent star-forming\nclouds evolves from initially large, weakly correlated filamentary structures\nto smaller, denser more correlated ones, and eventually to small, tightly\ncorrelated prestellar cores. We stress that the present results rely on a pure\nstatistical approach of density fluctuations and do not involve any specific\ncondition for the formation of prestellar cores. Interestingly enough, we show\nthat, under average conditions typical of Milky Way molecular clouds, this\ninvariant average mass is about a solar mass, providing an appealing\nexplanation for the apparent universality of the IMF under such environments.", "positive": "Ultraviolet spectra of extreme nearby star-forming regions ---\n approaching a local reference sample for JWST: Nearby dwarf galaxies provide a unique laboratory in which to test stellar\npopulation models below $Z_\\odot/2$. Such tests are particularly important for\ninterpreting the surprising high-ionization UV line emission detected at $z>6$\nin recent years. We present HST/COS ultraviolet spectra of ten nearby\nmetal-poor star-forming galaxies selected to show He II emission in SDSS\noptical spectra. The targets span nearly a dex in gas-phase oxygen abundance\n($7.8<12+\\log\\mathrm{O/H}<8.5$) and present uniformly large specific star\nformation rates (sSFR $\\sim 10^2$ $\\mathrm{Gyr}^{-1}$). The UV spectra confirm\nthat metal-poor stellar populations can power extreme nebular emission in\nhigh-ionization UV lines, reaching C III] equivalent widths comparable to those\nseen in systems at $z\\sim 6-7$. Our data reveal a marked transition in UV\nspectral properties with decreasing metallicity, with systems below\n$12+\\log\\mathrm{O/H}\\lesssim 8.0$ ($Z/Z_\\odot \\lesssim 1/5$) presenting minimal\nstellar wind features and prominent nebular emission in He II and C IV. This is\nconsistent with nearly an order of magnitude increase in ionizing photon\nproduction beyond the $\\mathrm{He^+}$-ionizing edge relative to H-ionizing flux\nas metallicity decreases below a fifth solar, well in excess of standard\nstellar population synthesis predictions. Our results suggest that often\nneglected sources of energetic radiation such as stripped binary products and\nvery massive O-stars produce a sharper change in the ionizing spectrum with\ndecreasing metallicity than expected. Consequently, nebular emission in C IV\nand He II powered by these stars may provide useful metallicity constraints in\nthe reionization era." }, { "anchor": "The physical constraints on a new LoBAL QSO at z=4.82: Very few low-ionization broad absorption line (LoBAL) QSOs have been found at\nhigh redshifts to date. One high-redshift LoBAL QSO, J0122+1216, was recently\ndiscovered at the Lijiang 2.4-m Telescope with an initial redshift\ndetermination of 4.76. Aiming to investigate its physical properties, we\ncarried out follow-up observations in the optical and near-IR spectroscopy.\nNear-IR spectra from UKIRT and P200 confirms that it is a LoBAL, with a new\nredshift determination of $4.82\\pm0.01$ based on the \\mgii~ emission-line. The\nnew \\mgii~ redshift determination reveals strong blueshifts and asymmetry of\nthe high-ionization emission lines. We estimated a black hole mass of $\\sim\n2.3\\times 10^9 M_\\odot$ and Eddington ratio of $\\sim 1.0$ according to the\nempirical \\mgii-based single-epoch relation and bolometric correction factor.\nIt is possible that strong outflows are the result of an extreme quasar\nenvironment driven by the high Eddington ratio. A lower limit on the outflowing\nkinetic power ($>0.9\\% L_{Edd}$) was derived from both emission and absorption\nlines, indicating these outflows play a significant role in the feedback\nprocess to regulate the growth of its black hole as well as host galaxy\nevolution.", "positive": "Gas inflows towards the nucleus of NGC1358: We use optical spectra from the inner 1.8 $\\times$ 2.5kpc$^2$ of the Seyfert\n2 galaxy NGC1358, obtained with the GMOS integral field spectrograph on the\nGemini South telescope at a spatial resolution of $\\approx$ 165pc, to assess\nthe feeding and feedback processes in this nearby active galaxy. Five gaseous\nkinematical components are observed in the emission line profiles. One of the\ncomponents is present in the entire field-of-view and we interpret it as due to\ngas rotating in the disk of the galaxy. Three of the remaining components we\ninterpret as associated to active galactic nucleus (AGN) feedback: a compact\nunresolved outflow in the inner 1 arcsec and two gas clouds observed at\nopposite sides of the nucleus, which we propose have been ejected in a previous\nAGN burst. The disk component velocity field is strongly disturbed by a large\nscale bar. The subtraction of a velocity model combining both rotation and bar\nflows reveals three kinematic nuclear spiral arms: two in inflow and one in\noutflow. We estimate the mass inflow rate in the inner 180pc obtaining\n$\\dot{M}_{in}$ $\\approx$ 1.5 $\\times 10^{-2}$M$_{\\odot}$yr$^{-1}$, about 160\ntimes larger than the accretion rate necessary to power this AGN." }, { "anchor": "Galaxy and Mass Assembly (GAMA): Morphological transformation of\n galaxies across the green valley: We explore constraints on the joint photometric and morphological evolution\nof typical low redshift galaxies as they move from the blue cloud through the\ngreen valley and onto the red sequence. We select GAMA survey galaxies with\n$10.25<{\\rm log}(M_*/M_\\odot)<10.75$ and $z<0.2$ classified according to their\nintrinsic $u^*-r^*$ colour. From single component S\\'ersic fits, we find that\nthe stellar mass-sensitive $K-$band profiles of red and green galaxy\npopulations are very similar, while $g-$band profiles indicate more disk-like\nmorphologies for the green galaxies: apparent (optical) morphological\ndifferences arise primarily from radial mass-to-light ratio variations.\nTwo-component fits show that most green galaxies have significant bulge and\ndisk components and that the blue to red evolution is driven by colour change\nin the disk. Together, these strongly suggest that galaxies evolve from blue to\nred through secular disk fading and that a strong bulge is present prior to any\ndecline in star formation. The relative abundance of the green population\nimplies a typical timescale for traversing the green valley $\\sim 1-2$~Gyr and\nis independent of environment, unlike that of the red and blue populations.\nWhile environment likely plays a r\\^ole in triggering the passage across the\ngreen valley, it appears to have little effect on time taken. These results are\nconsistent with a green valley population dominated by (early type) disk\ngalaxies that are insufficiently supplied with gas to maintain previous levels\nof disk star formation, eventually attaining passive colours. No single event\nis needed quench their star formation.", "positive": "M31* and its circumnuclear environment: We present a multiwavelength investigation of the circumnuclear environment\nof M31. Based on Chandra/ACIS data, we tightly constrain the X-ray luminosity\nof M31*, the central supermassive black hole of the galaxy, to be L (0.3-7\nkeV)<= 1.2x10^{36}erg/s, approximately 10^{-10} of the Eddington luminosity.\n From the diffuse X-ray emission, we characterize the circumnuclear hot gas\nwith a temperature of ~0.3 keV and a density of ~0.1 cm^{-3}. In the absence of\nan active SMBH and recent star formation, the most likely heating source for\nthe hot gas is Type Ia SNe. The presence of cooler, dusty gas residing in a\nnuclear spiral has long been known in terms of optical line emission and\nextinction. We further reveal the infrared emission of the nuclear spiral and\nevaluate the relative importance of various possible ionizing sources. We show\nevidence for interaction between the nuclear spiral and the hot gas, probably\nvia thermal evaporation. This mechanism lends natural understandings to 1) the\ninactivity of M31*, in spite of a probably continuous supply of gas from outer\ndisk regions, and 2) the launch of a bulge outflow of hot gas, primarily\nmass-loaded from the circumnuclear regions. One particular prediction of such a\nscenario is the presence of gas with intermediate temperatures arising from the\nconductive interfaces. The FUSE observations do show strong OVI$\\lambda$1032\nand 1038 absorption lines against the bulge starlight, but the effective OVI\ncolumn density (~4x10^{14} cm^{-2}), may be attributed to foreground gas\nlocated in the bulge and/or the highly inclined disk of M31. Our study strongly\nargues that stellar feedback, particularly in the form of energy release from\nSNe Ia, may play an important role in regulating the evolution of SMBHs and the\ninterstellar medium in galactic bulges." }, { "anchor": "Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised\n of Substructure: In the $\\Lambda$CDM paradigm the Galactic stellar halo is predicted to harbor\nthe accreted debris of smaller systems. To identify these systems, the H3\nSpectroscopic Survey, combined with $Gaia$, is gathering 6D phase-space and\nchemical information in the distant Galaxy. Here we present a comprehensive\ninventory of structure within 50 kpc from the Galactic center using a sample of\n5684 giants at $|b|>40^{\\circ}$ and $|Z|>2$ kpc. We identify known structures\nincluding the high-$\\alpha$ disk, the in-situ halo (disk stars heated to\neccentric orbits), Sagittarius (Sgr), $Gaia$-Sausage-Enceladus (GSE), the Helmi\nStreams, Sequoia, and Thamnos. Additionally, we identify the following new\nstructures: (i) Aleph ([Fe/H]$=-0.5$), a low eccentricity structure that rises\na surprising 10 kpc off the plane, (ii, iii) Arjuna ([Fe/H]$=-1.2$) and I'itoi\n([Fe/H]$<-2$), which comprise the high-energy retrograde halo along with\nSequoia, and (iv) Wukong ([Fe/H]$=-1.6$), a prograde phase-space overdensity\nchemically distinct from GSE. For each structure we provide [Fe/H],\n[$\\alpha$/Fe], and orbital parameters. Stars born within the Galaxy are a major\ncomponent at $|Z|\\sim$2 kpc ($\\approx$60$\\%$), but their relative fraction\ndeclines sharply to $\\lesssim$5$\\%$ past 15 kpc. Beyond 15 kpc, $>$80$\\%$ of\nthe halo is built by two massive ($M_{\\star}\\sim10^{8}-10^{9}M_{\\odot}$)\naccreted dwarfs: GSE ([Fe/H]$=-1.2$) within 25 kpc, and Sgr ([Fe/H]$=-1.0$)\nbeyond 25 kpc. This explains the relatively high overall metallicity of the\nhalo ([Fe/H]$\\approx-1.2$). We attribute $\\gtrsim$95$\\%$ of the sample to one\nof the listed structures, pointing to a halo built entirely from accreted\ndwarfs and heating of the disk.", "positive": "The OCCASO survey: Presentation and radial velocities of twelve Milky\n Way Open Clusters: Open clusters (OCs) are crucial for studying the formation and evolution of\nthe Galactic disc. However, the lack of a large number of OCs analyzed\nhomogeneously hampers the investigations about chemical patterns and the\nexistence of Galactocentric radial and vertical gradients, or an\nage-metallicity relation. To overcome this, we have designed the Open Cluster\nChemical Abundances from Spanish Observatories survey (OCCASO). We aim to\nprovide homogeneous radial velocities, physical parameters and individual\nchemical abundances of six or more Red Clump stars for a sample of 25 old and\nintermediate-age OCs visible from the Northern hemisphere. To do so, we use\nhigh resolution spectroscopic facilities (R> 62,000) available at Spanish\nobservatories. We present the motivation, design and current status of the\nsurvey, together with the first data release of radial velocities for 77 stars\nin 12 OCs, which represents about 50% of the survey. We include clusters never\nstudied with high-resolution spectroscopy before (NGC~1907, NGC~6991,\nNGC~7762), and clusters in common with other large spectroscopic surveys like\nthe Gaia-ESO Survey (NGC~6705) and APOGEE (NGC~2682 and NGC~6819). We perform\ninternal comparisons between instruments to evaluate and correct internal\nsystematics of the results, and compare our radial velocities with previous\ndeterminations in the literature, when available. Finally, radial velocities\nfor each cluster are used to perform a preliminar kinematic study in relation\nwith the Galactic disc." }, { "anchor": "Gas and Star Formation in the Circinus Galaxy: We present a detailed study of the Circinus Galaxy, investigating its star\nformation, dust and gas properties both in the inner and outer disk. To achieve\nthis, we obtained high-resolution Spitzer mid-infrared images with the IRAC\n(3.6, 5.8, 4.5, 8.0 micron) and MIPS (24 and 70 micron) instruments and\nsensitive HI data from the Australia Telescope Compact Array (ATCA) and the\n64-m Parkes telescope. These were supplemented by CO maps from the Swedish-ESO\nSubmillimetre Telescope (SEST). Because Circinus is hidden behind the Galactic\nPlane, we demonstrate the careful removal of foreground stars as well as large-\nand small-scale Galactic emission from the Spitzer images. We derive a visual\nextinction of Av = 2.1 mag from the Spectral Energy Distribution of the\nCircinus Galaxy and total stellar and gas masses of 9.5 x 10^{10} Msun and 9 x\n10^9 Msun, respectively. Using various wavelength calibrations, we find\nobscured global star formation rates between 3 and 8 Msun yr^{-1}. Star forming\nregions in the inner spiral arms of Circinus, which are rich in HI, are\nbeautifully unveiled in the Spitzer 8 micron image. The latter is dominated by\npolycyclic aromatic hydrocarbon (PAH) emission from heated interstellar dust.\nWe find a good correlation between the 8 micron emission in the arms and\nregions of dense HI gas. The (PAH 8 micron) / 24 micron surface brightness\nratio shows significant variations across the disk of Circinus.", "positive": "High gas fraction in a CO-selected main-sequence galaxy at $z > 3$: We report NOrthern Extended Millimetre Array (NOEMA) observations of warm\nmolecular gas traced by CO($5-4$) in a $z \\sim 3.2$ gas-rich main-sequence\ngalaxy (MS), initially serendipitously detected in CO($3-2$) emission in\n`blind' deep NOEMA observations. Our target shows a gas excitation consistent\nwith that seen in $z \\sim 1.5$ MS galaxies ($L'_{\\rm CO( 5 - 4)}/L'_{\\rm CO (3\n- 2)} = 0.41 \\pm 0.14$), albeit toward the low end, as well as a similar star\nformation efficiency based on the CO($3-2$) line luminosity and the $L_{\\rm\nIR}$. However, it shows a high molecular gas fraction ($f_{\\rm gas} = 0.9\\pm\n0.2$) as compared to $z\\sim 1.5$ MS galaxies ($f_{\\rm gas} \\sim 0.4$),\nconsistent with a cosmologically increasing gas fraction beyond $z\\gtrsim3$ and\nour current understanding of scaling relations between $z$, $f_{\\rm gas}$, the\nstellar mass $M_*$, and the specific star formation rate sSFR. Our results are\nconsistent with recent findings by the COLDz and ASPECS molecular line scan\nsurveys and suggest that deep searches for CO emission are a powerful means to\nidentify gas-rich, star-forming galaxies at high redshift." }, { "anchor": "Serendipity observations of far infrared cirrus emission in the Spitzer\n Infrared Nearby Galaxies Survey: Analysis of far-infrared correlations: We present an analysis of far-infrared dust emission from diffuse cirrus\nclouds. This study is based on serendipitous observations at 160 microns at\nhigh galactic latitude with the Multiband Imaging Photometer (MIPS) onboard the\nSpitzer Space Telescope by the Spitzer Infrared Nearby Galaxies Survey (SINGS).\nThese observations are complemented with IRIS data at 100 and 60 microns and\nconstitute one of the most sensitive and unbiased samples of far infrared\nobservations at small scale of diffuse interstellar clouds. Outside regions\ndominated by the cosmic infrared background fluctuations, we observe a\nsubstantial scatter in the 160/100 colors from cirrus emission. We compared the\n160/100 color variations to 60/100 colors in the same fields and find a trend\nof decreasing 60/100 with increasing 160/100. This trend can not be accounted\nfor by current dust models by changing solely the interstellar radiation field.\nIt requires a significant change of dust properties such as grain size\ndistribution or emissivity or a mixing of clouds in different physical\nconditions along the line of sight. These variations are important as a\npotential confusing foreground for extragalactic studies.", "positive": "ELVES III: Environmental Quenching by Milky Way-Mass Hosts: Isolated dwarf galaxies usually exhibit robust star formation but satellite\ndwarf galaxies are often devoid of young stars, even in Milky Way-mass groups.\nDwarf galaxies thus offer an important laboratory of the environmental\nprocesses that cease star formation. We explore the balance of quiescent and\nstar-forming galaxies (quenched fractions) for a sample of ~400 satellite\ngalaxies around 30 Local Volume hosts from the Exploration of Local VolumE\nSatellites (ELVES) Survey. We present quenched fractions as a function of\nsatellite stellar mass, projected radius, and host halo mass, to conclude that\noverall, the quenched fractions are similar to the Milky Way, dropping below\n50% at satellite M* ~ 10^8 M_sun. We may see hints that quenching is less\nefficient at larger radius. Through comparison with the semi-analytic modeling\ncode satgen, we are also able to infer average quenching times as a function of\nsatellite mass in host halo-mass bins. There is a gradual increase in quenching\ntime with satellite stellar mass rather than the abrupt change from rapid to\nslow quenching that has been inferred for the Milky Way. We also generally\ninfer longer average quenching times than recent hydrodynamical simulations.\nOur results are consistent with models that suggest a wide range of quenching\ntimes are possible via ram-pressure stripping, depending on the clumpiness of\nthe circumgalactic medium, the orbits of the satellites, and the degree of\nearlier preprocessing." }, { "anchor": "IGM Emission Observations with the Cosmic Web Imager: II. Discovery of\n Extended, Kinematically-Linked Emission around SSA22 Lyman-alpha Blob 2: The intergalactic medium (IGM) is the dominant reservoir of baryons,\ndelineates the large scale structure at low to moderate overdensities, and\nprovides gas from which galaxies form and evolve. Simulations of a Cold Dark\nMatter (CDM) dominated universe predict that the IGM is distributed in a cosmic\nweb of filaments, and that galaxies should form along and at the intersections\nof these filaments (Bond et al. 1994; Miralda-Escude et al. 1996). While\nobservations of QSO absorption lines and the large scale distribution of\ngalaxies have confirmed the CDM paradigm, the cosmic web has never been\nconfirmed by direct imaging. Here we report the Lyman-alpha blob 2 (LAB2) in\nSSA22, with the Cosmic Web Imager. This is an integral field spectrograph\noptimized for low surface brightness, extended emission. With 22 hours of total\nsource exposure, CWI has revealed that LAB2 has extended Lyman-alpha emission\nwhich is consistent with filaments. We perform tests to secure the robustness\nof this result, which relies on data with modest signal-to-noise ratio. We have\ndeveloped a smoothing algorithm that permits visualization of data cube slices\nalong image or spectral-image planes. With both raw and smoothed data cubes we\ndemonstrate that the filaments are kinematically associated with LAB2 and\ndisplay double-peaked profiles of optically thick Lyman-alpha emission. The\nflux is 10 to 20x brighter than expected for the emission from the IGM but is\nconsistent with boosted fluorescence from a buried QSO or gravitation cooling\nradiation. Using emission models we infer a baryon mass in the filaments of at\nleast 1-4x10e11 Solar Mass, and the dark halo mass is at least 2x10e12 Solar\nMass. The spatial kinematic morphology is more consistent with inflow from the\ncosmic web than outflow. LAB2 and the surrounding gas have significant and\ncoaligned angular momentum, strengthening the case for their association.", "positive": "MAGNIF: A Tentative Lensed Rotating Disk at $z=8.34$ detected by JWST\n NIRCam WFSS with Dynamical Forward Modeling: We report galaxy MACS0416-Y3 behind the lensing cluster MACSJ0416.1--2403 as\na tentative rotating disk at $z=8.34$ detected through its [OIII]$\\lambda5007$\nemission in JWST NIRCam wide-field slitless spectroscopic observations. The\ndiscovery is based on our new grism dynamical modeling methodology for JWST\nNIRCam slitless spectroscopy, using the data from ``Median-band Astrophysics\nwith the Grism of NIRCam in Frontier Fields'' (MAGNIF), a JWST Cycle-2 program.\nThe [OIII]$\\lambda5007$ emission line morphology in grism data shows velocity\noffsets compared to the F480M direct imaging, suggestive of rotation. Assuming\na geometrically thin disk model, we constrain the rotation velocity of $v_{\\rm\nrot}=58^{+53}_{-35}$ km s$^{-1}$ via forward modeling of the two-dimensional\n(2D) spectrum. We obtain the kinematic ratio of $v_{\\rm\nrot}/\\sigma_v=1.6^{+1.9}_{-0.9}$, where $\\sigma_v$ is the velocity dispersion,\nin line with a quasi-stable thin disk. The resulting dynamical mass is\nestimated to be $\\log(M_{\\rm dyn}/M_{\\odot})=8.4^{+0.5}_{-0.7}$. If the\nrotation confirmed, our discovery suggests that rotating gaseous disks may have\nalready existed within 600 million years after Big Bang." }, { "anchor": "A 10,000 star spectroscopic survey of the thick disk-halo interface :\n Phase-space sub-structure in the thick disk: We analyse a 10,000 star spectroscopic survey, focused on Galactic thick disk\nstars typically 2-5 kpc from the Sun, carried out using the AAOmega\nSpectrograph on the AAT. We develop methods for completeness-correction of the\nsurvey based on SDSS photometry, and we derive star distances using an improved\nisochrone-fitting method with accuracies better than 10%. We determine the\nlarge-scale kinematic (Vphi=172 km/s and sigma(phi,r,z) = (49,51,40) km/s), and\nabundance properties of the thick disk, showing these representative values are\na fair description within about 3 kpc of the sun, and in the range 1-3 kpc from\nthe Galactic Plane. We identify a substantial overdensity in lines of sight\ntowards the inner Galaxy, with metallicity [Fe/H] -1 dex, and higher line of\nsight velocities than the thick disk, localised along the direction\n(l,b)=(48,-26). This overdensity appears to be towards, but closer than, the\nknown Hercules-Aquila halo overdensity and may be related to the\nHumphreys-Larsen inner galaxy thick disk asymmetry.", "positive": "The X-shooter/ALMA Sample of Quasars in the Epoch of Reionization. II.\n Black Hole Masses, Eddington Ratios, and the Formation of the First Quasars: We present measurements of black hole masses and Eddington ratios for a\nsample of 38 bright (M$_{1450}$ < -24.4 mag) quasars at 5.8 < z < 7.5, derived\nfrom VLT/X-shooter near-IR spectroscopy of their broad CIV and MgII emission\nlines. The black hole masses (on average M$_{BH}$ ~ 4.6 x 10$^9$ M$_{\\odot}$)\nand accretion rates (with Eddington ratios ranging between 0.1 and 1.0) are\nbroadly consistent with that of similarly luminous 0.3 < z < 2.3 quasars, but\nthere is evidence for a mild increase in the median Eddington ratio going\ntowards z > 6. Combined with deep ALMA observations of the [CII] 158 $\\mu$m\nline from the quasar host galaxies and VLT/MUSE investigations of the extended\nLy$\\alpha$ halos, this study provides fundamental clues to models of the\nformation and growth of the first massive galaxies and black holes. Compared to\nlocal scaling relations, z > 5.7 black holes appear to be over-massive with\nrespect to their host galaxies, and their accretion properties do not change\nwith host galaxy morphology. Under the assumption that the kinematics of the T\n~ 10$^4$ K gas, traced by the extended Ly$\\alpha$ halos, are dominated by the\ngravitational potential of the dark matter halo, we report a similar relation\nbetween the black hole mass and circular velocity to the one reported for z ~ 0\ngalaxies. These results paint a picture where the first supermassive black\nholes reside in massive halos at z > 6 and lead the first stages of galaxy\nformation by rapidly growing in mass with a duty cycle of order unity. However,\nthis duty cycle needs to drastically drop towards lower redshifts, while the\nhost galaxies continue forming stars at a rate of hundreds of solar masses per\nyear, sustained by the large reservoirs of cool gas surrounding them." }, { "anchor": "On the rotation curve of disk galaxies in General Relativity: Recently, it has been suggested that the phenomenology of flat rotation\ncurves observed at large radii in the equatorial plane of disk galaxies can be\nexplained as a manifestation of General Relativity instead of the effect of\nDark Matter halos. In this paper, by using the well known weak field, low\nvelocity gravitomagnetic formulation of GR, the expected rotation curves in GR\nare rigorously obtained for purely baryonic disk models with realistic density\nprofiles, and compared with the predictions of newtonian gravity for the same\ndisks in absence of Dark Matter. As expected, the resulting rotation curves are\nindistinguishable, with GR corrections at all radii of the order of\n$v^2/c^2\\approx 10^{-6}$. Next, the gravitomagnetic Jeans equations for\ntwo-integral stellar systems are derived, and then solved for the\nMiyamoto-Nagai disk model, showing that finite-thickness effects do not change\nthe previous conclusions. Therefore, the observed phenomenology of galactic\nrotation curves at large radii requires Dark Matter in GR exactly as in\nnewtonian gravity, unless the cases here explored are reconsidered in the full\nGR framework with substantially different results (with the surprising\nconsequence that the weak field approximation of GR cannot be applied to the\nstudy of rotating systems in the weak field regime). In the paper, the\nmathematical framework is described in detail, so that the present study can be\nextended to other disk models, or to elliptical galaxies (where Dark Matter is\nalso required in newtonian gravity, but their rotational support can be much\nless than in disk galaxies).", "positive": "Accretion driven turbulence in filaments II: Effects of self-gravity: We extend our previous work on simulations with the code RAMSES on accretion\ndriven turbulence by including self-gravity and study the effects of core\nformation and collapse. We show that radial accretion onto filaments drives\nturbulent motions which are not isotropic but radially dominated. In contrast\nto filaments without gravity, the velocity dispersion of self-gravitating\nfilaments does not settle in an equilibrium. Despite showing similar amounts of\ndriven turbulence, they continually dissipate their velocity dispersion until\nthe onset of core formation. This difference is connected to the evolution of\nthe radius as it determines the dissipation rate. In the non-gravitational case\nfilament growth is not limited and its radius grows linearly with time. In\ncontrast, there is a maximum extent in the self-gravitational case resulting in\nan increased dissipation rate. Furthermore, accretion driven turbulence shows a\nradial profile which is anti-correlated with density. This leads to a constant\nturbulent pressure throughout the filament. As the additional turbulent\npressure does not have a radial gradient it does not contribute to the\nstability of filaments and does not increase the critical line-mass. However,\nthis radial turbulence does affect the radius of a filament, adding to the\nextent and setting its maximum value. Moreover, the radius evolution also\naffects the growth timescale of cores which compared to the timescale of\ncollapse of an accreting filament limits core formation to high line-masses." }, { "anchor": "Powerful t-SNE technique leading to clear separation of type-2 AGN and\n HII galaxies in BPT diagrams: Narrow emission-line galaxies can be distinguished in the well-known BPT\ndiagrams through narrow emission line properties. However, there are no\nboundaries visible to the naked eye between type-2 AGN and HII galaxies in BPT\ndiagrams, besides the extreme dividing lines expected by theoretical\nphotoionization models. Here, based on powerful t-SNE technique applied to the\nlocal narrow emission-line galaxies in SDSS DR15, type-2 AGN and HII galaxies\ncan be clearly separated in the t-SNE determined two-dimensional projected map,\nand then the dividing lines can be mathematically determined in BPT diagrams,\nleading to charming harmonization of the theoretical expectations and the\nactual results from real observed properties. The results not only provide an\ninteresting and robust method to determine the dividing lines in BPT diagrams\nthrough the powerful t-SNE technique, but also lead to further confirmation on\npreviously defined composite galaxies more efficiently classified in the BPT\ndiagram of [OIII]/H$\\beta$ versus [NII]/H$\\alpha$.", "positive": "Distribution and mass of diffuse and dense CO gas in the Milky Way: Emission from carbon monoxide (CO) is ubiquitously used as a tracer of dense\nstar forming molecular clouds. There is, however, growing evidence that a\nsignificant fraction of CO emission originates from diffuse molecular gas.\nQuantifying the contribution of diffuse CO-emitting gas is vital for\nunderstanding the relation between molecular gas and star formation. We examine\nthe Galactic distribution of two CO-emitting gas components, a high column\ndensity component detected in 13CO and 12CO, and a low column density component\ndetected in 12CO, but not in 13CO. The \"diffuse\" and \"dense\" components are\nidentified using a combination of smoothing, masking, and erosion/dilation\nprocedures, making use of three large-scale 12CO and 13CO surveys of the Inner\nand Outer Milky Way. The diffuse component, which globally represents 25\n(1.5x1e8 Mo) of the total molecular gas mass (6.5x1e8 Mo), is more extended\nperpendicular to the Galactic plane. The fraction of diffuse gas increases from\n15% at a galactocentric radius of 3 kpc to 50% at 15 kpc, and increases with\ndecreasing surface density. In the Inner Galaxy, a yet denser component traced\nby CS emission represents 14% of the total molecular gas mass traced by 12CO\nemission. Only 14% of the molecular gas mass traced by 12CO emission is\nidentified as part of molecular clouds in 12CO surveys by cloud identification\nalgorithms. This study indicates that CO emission not only traces star forming\nclouds, but also a significant diffuse molecular ISM component." }, { "anchor": "Winds versus jets: a comparison between black hole feedback modes in\n simulations of idealized galaxy groups and clusters: Using the SWIFT simulation code we study different forms of active galactic\nnuclei (AGN) feedback in idealized galaxy groups and clusters. We first present\na physically motivated model of black hole (BH) spin evolution and a numerical\nimplementation of thermal isotropic feedback (representing the effects of\nenergy-driven winds) and collimated kinetic jets that they launch at different\naccretion rates. We find that kinetic jet feedback is more efficient at\nquenching star formation in the brightest cluster galaxies (BCGs) than thermal\nisotropic feedback, while simultaneously yielding cooler cores in the\nintracluster medium (ICM). A hybrid model with both types of AGN feedback\nyields moderate star formation rates, while having the coolest cores. We then\nconsider a simplified implementation of AGN feedback by fixing the feedback\nefficiencies and the jet direction, finding that the same general conclusions\nhold. We vary the feedback energetics (the kick velocity and the heating\ntemperature), the fixed efficiencies and the type of energy (kinetic versus\nthermal) in both the isotropic and the jet case. The isotropic case is largely\ninsensitive to these variations. In particular, we highlight that kinetic\nisotropic feedback (used e.g. in IllustrisTNG) is similar in its effects to its\nthermal counterpart (used e.g. in EAGLE). On the other hand, jet feedback must\nbe kinetic in order to be efficient at quenching. We also find that it is much\nmore sensitive to the choice of energy per feedback event (the jet velocity),\nas well as the efficiency. The former indicates that jet velocities need to be\ncarefully chosen in cosmological simulations, while the latter motivates the\nuse of BH spin evolution models.", "positive": "Interpreting the complex CMDs of the Magellanic Clouds clusters: The Magellanic Clouds host a large population of massive (> 10^4 Msun) star\nclusters with ages ranging from a few Myr to 12 Gyr. In nearly all cases, close\ninspection of their CMDs reveals features that deviate from expectations of a\nclassic isochrone. Young (< 2 Gyr) clusters show extended main sequence\nturnoffs and in some cases split/dual main sequences. Clusters older than ~ 2\nGyr show splitting in the red giant branches when viewed in UV filters that are\nsensitive to abundance variations (in particular nitrogen). A distribution of\nstellar rotation rates appears to be the cause of the complex features observed\nin the young and intermediate age clusters, while above ~ 2 Gyr the features\nseem to be the same light-element abundance variations as observed in the\nancient Galactic globular clusters, a.k.a. \"multiple populations\". Here, we\nprovide an overview of current observations and their interpretations and\nsummarise possible links between all the classes of complexities, regardless of\nage." }, { "anchor": "Towards a Complete Census of AGNs in Nearby Galaxies: The Incidence of\n Growing Black Holes: We investigate the local supermassive black hole (SMBH) density function and\nrelative mass accretion rates of all active galactic nuclei (AGNs) identified\nin a volume-limited sample of infrared (IR) bright galaxies (L_IR > 3 x 10^9\nL_sun) to D<15 Mpc (Goulding & Alexander 2009). A database of accurate SMBH\nmass (M_BH) estimates is compiled from literature sources using physically\nmotivated AGN modeling techniques (reverberation mapping, maser mapping and gas\nkinematics) and well-established indirect M_BH estimation methods (the M-sigma\nand M_BH-L_(K,bul) relations). For the three sources without previously\npublished M_BH estimates, we use 2MASS K-band imaging and GALFIT to constrain\nthe bulge luminosities, and hence SMBH masses. In general, we find the AGNs in\nthe sample host SMBHs which are spread over a wide mass range (M_BH ~ (0.1-30)\nx 10^7 M_sun), but with the majority in the poorly studied M_BH ~ 10^6-10^7\nM_sun region. Using sensitive hard X-ray (2-10 keV) and mid-IR constraints we\ncalculate the bolometric luminosities of the AGNs (L_(Bol,AGN)) and use them to\nestimate relative mass accretion rates. We use these data to calculate the\nvolume-average SMBH growth rate of galaxies in the local Universe and find that\nthe AGNs hosting SMBHs in the mass range M_BH ~ 10^6-10^7 M_sun are dominated\nby optically unidentified AGNs. These relatively small SMBHs are acquiring a\nsignificant proportion of their mass in the present-day, and are amongst the\nmost rapidly growing in the local Universe (SMBH mass doubling times of ~6\nGyrs). Additionally, we find tentative evidence for an increasing\nvolume-weighted AGN fraction with decreasing SMBH mass in the M_BH ~ 10^6-10^8\nM_sun range. Overall, we conclude that significant mass accretion onto small\nSMBHs may be missed in even the most sensitive optical surveys due to absent or\nweak optical AGN signatures.", "positive": "The detections of inflowing gas from narrow absorption lines at the\n parsec scale: Inflows at the dusty torus and smaller scales is crucial to investigate the\nprocess of supermassive black hole accretion. However, only few cases of\ninflowing gas at small scales have been reported through redshifted broad\nabsorption lines so far. Here we report 9 redshifted narrow absorption lines\n(NALs) of $\\rm Mg^+$ ions with inflowing speeds of 1071 -- 1979 km/s, which are\nlikely along the directions close to the axes of accretion disks. The quasars\nshowing inflowing Mg II NALs have on average slightly smaller Eddington ratios\nwhen compared to the sources with outflow Mg II NALs. The upper limits of\nlocations of the detected NALs are at parsec scale, around the distances of\ndusty tori to central SMBHs. The one possible origin of these infalling NALs is\nfrom dusty tori. Of course, these infalling NALs can also be naturally\nexplained by chaotic cold accretion resulted from the nonlinear interaction of\nactive galactic nucleus (AGN) jets with the interstellar medium, and these cold\ngaseous blobs may originally precipitate in metal-rich trailing outflows\nuplifted by AGN jet ejecta. The infalling NALs may thus provide direct evidence\nfor cold gas precipitation and accretion in AGN feedback processes, and provide\nthe direct evidence of inflowing gas along the directions close to quasar jets\nand at parsec scale. It does not matter whether these infalling NALs are from\nthe dusty tori or the interaction of AGN jets with the ISM, the infalling NALs\ncannot provide sufficient fuels to power the quasars." }, { "anchor": "Unveiling The Physics of Star Formation and Feedback in Galaxies: Recent studies show the importance of feedback in the evolution of the star\nformation rate in the Universe. However, the nature and physics of the feedback\nare still pressing questions. Radio continuum observations can provide unique\ndust-unbiased tracers of massive star formation and of the interstellar medium\n(ISM) and hence are ideal to address the regulation of star formation in\ngalaxies. Our multi-frequency and multi-resolution radio surveys in nearby\ngalaxies enable us to trace various phases of star formation and dissect the\nthermal and nonthermal ISM in galaxies. Mapping the cosmic ray electron energy\nindex and magnetic field strength, we have found observational evidence that\nmassive star formation significantly affects the energy balance in the ISM\nthrough the injection and acceleration of cosmic rays and the amplification of\nmagnetic fields. How the next generation of stars could form in such a\nmagnetized and turbulent ISM will be addressed in our 'EVLA cloud-scale survey\nof the local group galaxy M33' and in forthcoming surveys with the SKA.", "positive": "Exploring the SDSS Photometric Galaxies with Clustering Redshifts: We apply clustering-based redshift inference to all extended sources from the\nSloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We\nmap the relationships between colours and redshift, without assumption of the\nsources' spectral energy distributions (SED). We identify and locate\nstar-forming, quiescent galaxies, and AGN, as well as colour changes due to\nspectral features, such as the 4000 \\AA{} break, redshifting through specific\nfilters. Our mapping is globally in good agreement with colour-redshift tracks\ncomputed with SED templates, but reveals informative differences, such as the\nneed for a lower fraction of M-type stars in certain templates. We compare our\nclustering-redshift estimates to photometric redshifts and find these two\nindependent estimators to be in good agreement at each limiting magnitude\nconsidered. Finally, we present the global clustering-redshift distribution of\nall Sloan extended sources, showing objects up to z ~ 0.8. While the overall\nshape agrees with that inferred from photometric redshifts, the clustering\nredshift technique results in a smoother distribution, with no indication of\nstructure in redshift space suggested by the photometric redshift estimates\n(likely artifacts imprinted by their spectroscopic training set). We also infer\na higher fraction of high redshift objects. The mapping between the four\nobserved colours and redshift can be used to estimate the redshift probability\ndistribution function of individual galaxies. This work is an initial step\ntowards producing a general mapping between redshift and all available\nobservables in the photometric space, including brightness, size,\nconcentration, and ellipticity." }, { "anchor": "A first measurement of the Proper Motion of the Leo II dwarf spheroidal\n galaxy: We use 14-year baseline images obtained with the Wide Field Planetary Camera\n2 on board the Hubble Space telescope to derive a proper motion for one of the\nMilky Way's most distant dwarf spheroidal companions, Leo II, relative to an\nextragalactic background reference frame. Astrometric measurements are\nperformed in the effective point spread function (ePSF) formalism using our own\ndeveloped code. An astrometric reference grid is defined using 3,224 stars that\nare members of Leo II that are brighter than magnitude 25 in the F814W band. We\nidentify 17 compact extra-galactic sources, for which we measure a systemic\nproper motion relative to this stellar reference grid. We derive a proper\nmotion [\\mu_{\\alpha},\\mu_{\\delta}]=[+104+/-113,-33+/-151] microarcseconds/yr\nfor Leo II in the heliocentric reference frame. Though marginally detected, the\nproper motion yields constraints on the orbit of Leo II. Given a distance of\n230 Kpc and a heliocentric radial velocity +79 km/s, and after subtraction of\nthe solar motion, our measurement indicates a total orbital motion\n266.1+/-128.7 km/s in the Galactocentric reference frame, with a radial\ncomponent +21.5+/-4.3 km/s and tangential component 265.2+/-129.4 km/s. The\nsmall radial component indicates that Leo II either has a low-eccentricity\norbit, or is currently close to perigalacticon or apogalacticon distance. We\nsee evidence for systematic errors in the astrometry of the extragalactic\nsources which, while close to being point sources, are slightly resolved in the\nHST images. We argue that more extensive observations at later epochs will be\nnecessary to better constrain the proper motion of Leo II. We provide a\ndetailed catalog of the stellar and extragalactic sources identified in the HST\ndata which should provide a solid early-epoch reference for future astrometric\nmeasurements.", "positive": "Renewal of Transient Spiral Modes in Disk Galaxies: Spiral structure in disk galaxies could arise from transient modes that\ncreate conditions conducive for their regeneration; this is the proposal of\nSellwood and Carlberg, based on simulations of stellar disks. The linear\nresponse of an axisymmetric stellar disk, to an adiabatic non-axisymmetric\ntransient mode, gives a final distribution function (DF) that is equal to the\ninitial DF everywhere in phase space, except at the Lindblad and corotation\nresonances where the final DF is singular. We use the nonlinear theory of\nadiabatic capture into resonance to resolve the singularities and calculate the\nfinite changes in the DF. These take the form of axisymmetric \"scars\"\nconcentrated around resonances, whose DFs have simple general forms. Global\nchanges in the physical properties are explored for a cool Mestel disk: we\ncalculate the DFs of scars, and estimate the changes in the disk angular\nmomentum, surface density and orbital frequencies leading to shifts of\nresonances. Resonant torques between disk stars and any new linear\nnon-axisymmetric mode are suppressed within a scar, as is epicyclic heating.\nSince all the resonances of a linear mode with the same angular wavenumber and\npattern speed as its precursor lie inside the scars of the precursor, it\nsuffers less damping. Hence, scars filter the spectrum of noise-generated\nmodes, promoting the renewal of a few select modes. Relic scars sustained by a\ngalaxy disk, due to past tidal interaction with a passing companion, may still\nbe active enablers of non-axisymmetric modes, such as the two-armed \"grand\ndesign\" spiral patterns." }, { "anchor": "A multi-wavelength view of the Galactic center dust ridge reveals little\n star formation: The Galactic center dust ridge consists of a narrow string of massive\ncondensations identified in submillimeter dust continuum emission. To determine\nwhether new high-mass stars are forming in this region, we performed new\nobservations at 870 $\\mu$m with the Atacama Pathfinder Experiment telescope and\nat 8.4 GHz with the Very Large Array. We complement our data with recent maser\nand mid-infrared results. The ridge's clouds are dark at mid-infrared\nwavelengths, indicating the presence of cold, high column density material. In\ncombination with existing temperature measurements in the dust ridge, we\ndetermined the masses of the largest clouds. The results show that the dust\nridge contains a very massive reservoir of molecular material. We find five\nradio sources at 8.4 GHz in the general dust ridge vicinity but outside of the\ndust ridge clouds, which are probably all excited by massive young stars, whose\nproperties we constrain. Our observations exclude the existence of zero age\nmain sequence stars with spectral types earlier than B0.5 within the dust ridge\nclouds. The only indication of ongoing high-mass star formation inside the\nclouds are class II methanol masers that are found in two of the clouds. Except\nfor a weak water maser, found in previous observations, no signs of star\nformation are detected in the massive cloud M0.25+0.012.", "positive": "Galaxy interactions in IllustrisTNG-100, I: The power and limitations of\n visual identification: We present a sample of 446 galaxy pairs constructed using the cosmological\nsimulation IllustrisTNG-100 at z = 0, with M$_{FoF, dm}$ =\n10$^{11}$-10$^{13.5}$ M$_{\\odot}$. We produce ideal mock SDSS g-band images of\nall pairs to test the reliability of visual classification schema employed to\nproduce samples of interacting galaxies. We visually classify each image as\ninteracting or not based on the presence of a close neighbour, the presence of\nstellar debris fields, disturbed discs, and/or tidal features. By inspecting\nthe trajectories of the pairs, we determine that these indicators correctly\nidentify interacting galaxies $\\sim45\\%$ of the time. We subsequently split the\nsample into the visually identified interacting pairs (VIP; 38 pairs) and those\nwhich are interacting but are not visually identified (nonVIP; 47 pairs). We\nfind that VIP have undergone a close passage nearly twice as recently as the\nnonVIP, and typically have higher stellar masses. Further, the VIP sit in dark\nmatter haloes that are approximately 2.5 times as massive, in environments\nnearly 2 times as dense, and are almost a factor of 10 more affected by the\ntidal forces of their surroundings than the nonVIP. These factors conspire to\nincrease the observability of tidal features and disturbed morphologies, making\nthe VIP more likely to be identified. Thus, merger rate calculations which rely\non stellar morphologies are likely to be significantly biased toward massive\ngalaxy pairs which have recently undergone a close passage." }, { "anchor": "A CEMP-no star in the ultra-faint dwarf galaxy Pisces II: A probable carbon enhanced metal-poor (CEMP) star, Pisces II 10694, was\ndiscovered recently in the ultra-faint (UFD) galaxy Pisces II. This galaxy is\nsupposed to be very old, suspected to include dark matter, and likely formed\nthe bulk of its stars before the reionisation of the Universe.\n New abundances have been obtained from observations of Pisces II 10694 at the\nKueyen ESO VLT telescope, using the high-efficiency spectrograph: X-Shooter.\n We found that Pisces II 10694 is a CEMP-no star with [Fe/H]=-2.60 dex.\nCareful measurements of the CH and C2 bands confirm the enhancement of the C\nabundance ([C/Fe]=+1.23). This cool giant has very probably undergone extra\nmixing and thus its original C abundance could be even higher. Nitrogen, O, Na,\nand Mg are also strongly enhanced, but from Ca to Ni the ratios [X/Fe] are\nsimilar to those observed in classical galactic very metal-poor stars. With its\nlow Ba abundance ([Ba/Fe] =-1.10 dex) Pisces II 10694 is a CEMP-no star. No\nvariation in the radial velocity could be detected between the years 2015 and\n2017. The pattern of the elements abundance has a shape similar to the pattern\nfound in galactic CEMP-no stars like CS 22949-037 ([Fe/H]=-4.0) or SDSS\nJ1349+1407 ([Fe/H]=-3.6). The existence of a CEMP-no star in the UFD galaxy\nPisc II suggests that this small galaxy likely hosted zero-metallicity stars.\nThis is consistent with theoretical predictions of cosmological models\nsupporting the idea that UFD galaxies are the living fossils of the first\nstar-forming systems.", "positive": "Simulating the Diverse Instabilities of Dust in Magnetized Gas: Recently Squire & Hopkins showed that charged dust grains moving through\nmagnetized gas under the influence of any external force (e.g. radiation\npressure, gravity) are subject to a spectrum of instabilities. Qualitatively\ndistinct instability families are associated with different Alfvenic or\nmagnetosonic waves and drift or gyro motion. We present a suite of simulations\nexploring these instabilities, for grains in a homogeneous medium subject to an\nexternal acceleration. We vary parameters such as the ratio of Lorentz-to-drag\nforces on dust, plasma $\\beta$, size scale, and acceleration. All regimes\nstudied drive turbulent motions and dust-to-gas fluctuations in the saturated\nstate, can rapidly amplify magnetic fields into equipartition with velocity\nfluctuations, and produce instabilities that persist indefinitely (despite\nrandom grain motions). Different parameters produce diverse morphologies and\nqualitatively different features in dust, but the saturated gas state can be\nbroadly characterized as anisotropic magnetosonic or Alfvenic turbulence.\nQuasi-linear theory can qualitatively predict the gas turbulent properties.\nTurbulence grows from small to large scales, and larger-scale modes usually\ndrive more vigorous gas turbulence, but dust velocity and density fluctuations\nare more complicated. In many regimes, dust forms structures (clumps,\nfilaments, sheets) that reach extreme over-densities (up to $\\gg 10^{9}$ times\nmean), and exhibit substantial sub-structure even in nearly-incompressible gas.\nThese can be even more prominent at lower dust-to-gas ratios. In other regimes,\ndust self-excites scattering via magnetic fluctuations that isotropize and\namplify dust velocities, producing fast, diffusive dust motions." }, { "anchor": "SMASHing THE LMC: Mapping a Ring-like Stellar Overdensity in the LMC\n Disk: We explore the stellar structure of the Large Magellanic Cloud (LMC) disk\nusing data from the Survey of the MAgellanic Stellar History (SMASH) and the\nDark Energy Survey. We detect a ring-like stellar overdensity in the red clump\nstar count map at a radius of ~6 degrees (~5.2 kpc at the LMC distance) that is\ncontinuous over ~270 degrees in position angle and is only limited by the\ncurrent data coverage. The overdensity shows an amplitude up to 2.5 times\nhigher than that of the underlying smooth disk. This structure might be related\nto the multiple arms found by de Vaucouleurs. We find that the overdensity\nshows spatial correlation with intermediate-age star clusters, but not with\nyoung (< 1 Gyr) main-sequence stars, indicating the stellar populations\nassociated with the overdensity are intermediate in age or older. Our findings\non the LMC overdensity can be explained by either of two distinct formation\nmechanisms of a ring-like overdensity: (1) the overdensity formed out of an\nasymmetric one-armed spiral wrapping around the LMC main body, which is induced\nby repeated encounters with the Small Magellanic Cloud (SMC) over the last Gyr,\nor (2) the overdensity formed very recently as a tidal response to a direct\ncollision with the SMC. Although the measured properties of the overdensity\nalone cannot distinguish between the two candidate scenarios, the consistency\nwith both scenarios suggests that the ring-like overdensity is likely a product\nof tidal interaction with the SMC, but not with the Milky Way halo.", "positive": "Tip of the red giant branch distance to the nearby dwarf galaxy [TT2009]\n 25 in the NGC 891 group: Dwarf galaxies are key objects for small-scale cosmological tests like the\nabundance problems or the planes-of-satellites problem. It is therefore a\ncrucial task to get accurate information for as many nearby dwarf galaxies as\npossible. Using extremely deep, ground-based $V$ and $i$-band Subaru Suprime\nCam photometry with a completeness of $i=27$ mag, we measure the tip of the red\ngiant branch distance for the dwarf galaxy [TT2009] 25. This dwarf resides in\nthe field around the Milky Way-analog NGC 891. By using a Bayesian approach, we\nmeasure a distance of $10.28^{+1.17}_{-1.73}$ Mpc, which is consistent with the\ndistance of NGC 891, thus we confirm it as a member of NGC 891. The dwarf\ngalaxy follows the scaling relations defined by the Local Group dwarfs. We do\nnot find an extended stellar halo around [TT2009] 25. In the small field of\nview of 100 kpc covered by the survey, only one bright dwarf galaxy and the\ngiant stream are apparent. This is comparable to the Milky Way, where one\nbright dwarfs reside in the same volume, as well as the Sagittarius stream -\nexcluding satellites which are farther away but would be projected in the\nline-of-sight. It is thus imperative to survey for additional dwarf galaxies in\na larger area around NGC 891 to test the abundance of dwarf galaxies and\ncompare it to the number of satellites around the Milky Way." }, { "anchor": "Detection of Intermediate-Mass Black Holes in Globular Clusters Using\n Gravitational Lensing: Recent observations suggest the presence of supermassive black holes at the\ncenters of many galaxies. The existence of intermediate-mass black holes\n(IMBHs) in globular clusters has also been predicted. We focus on gravitational\nlensing as a new way to explore these entities. It is known that the mass\ndistribution of a self-gravitating system such as a globular cluster changes\ngreatly depending on the presence or absence of a central massive object. After\nconsidering possible mass distributions for a globular cluster belonging to the\nMilky Way galaxy, we estimate that the effect on the separation angle of\ngravitational lensing due to an IMBH would be of milliarcsecond order.", "positive": "The origin of the atomic and molecular gas contents of early-type\n galaxies. II. Misaligned gas accretion: We study the origin of the wide distribution of angles between the angular\nmomenta of the stellar and gas components, $\\alpha_{\\rm G,S}$, in early-type\ngalaxies (ETGs). We use the GALFORM model of galaxy formation, set in the\n$\\Lambda$ cold dark matter framework, and coupled it with a Monte-Carlo\nsimulation to follow the angular momenta flips driven by matter accretion onto\nhaloes and galaxies. We consider a gas disk to be misaligned with respect to\nthe stellar body if $\\alpha_{\\rm G,S}>30$~degrees. By assuming that the only\nsources of misaligments in galaxies are galaxy mergers, we place a lower limit\nof $2-5$ per cent on the fraction of ETGs with misaligned gas/stellar\ncomponents. These low fractions are inconsistent with the observed value of\n$\\approx 42\\pm 6$ per cent in ATLAS$^{\\rm 3D}$. In the more general case, in\nwhich smooth gas accretion in addition to galaxy mergers can drive\nmisalignments, our calculation predicts that $\\approx 46$ per cent of ETGs have\n$\\alpha_{\\rm G,S}>30$~degrees. In this calculation, we find correlations\nbetween $\\alpha_{\\rm G,S}$ and stellar mass, cold gas fraction and star\nformation rate, such that ETGs with high masses, low cold gas fractions and low\nstar formation rates are more likely to display aligned cold gas and stellar\ncomponents. We confirm these trends observationally for the first time using\nATLAS$^{\\rm 3D}$ data. We argue that the high fraction of misaligned gas discs\nobserved in ETGs is mostly due to smooth gas accretion (e.g. cooling from the\nhot halo of galaxies) which takes place after most of the stellar mass of the\ngalaxy is in place and comes misaligned with respect to the stellar component.\nGalaxies that have accreted most of their cold gas content prior to the time\nwhere most of the stellar mass was in place show aligned components." }, { "anchor": "Chemical evolution in star clusters: the role of mass and environment: The process of chemical self-enrichment in stellar systems can be affected by\nthe total mass of the system and the conditions of the large-scale environment.\nGlobular clusters are a special dark matter-free case of chemical evolution, in\nwhich the only self-enrichment comes from material processed in stars, and only\ntwo bursts of star formation occur. We describe how observations of\nintermediate-age star clusters in the Large Magellanic Cloud can provide\ninsight on the ways that mass and environment can affect the process of\nchemical enrichment in star clusters.", "positive": "The Unique Na:O Abundance Distribution in NGC 6791: The First Open(?)\n Cluster with Multiple Populations: Almost all globular clusters investigated exhibit a spread in their light\nelement abundances, the most studied being a Na:O anticorrelation. In contrast,\nopen clusters show a homogeneous composition and are still regarded as Simple\nStellar Populations. The most probable reason for this difference is that\nglobulars had an initial mass high enough to retain primordial gas and ejecta\nfrom the first stellar generation and thus formed a second generation with a\ndistinct composition, an initial mass exceeding that of open clusters. NGC 6791\nis a massive open cluster, and warrants a detailed search for chemical\ninhomogeneities. We collected high resolution, high S/N spectra of 21 members\ncovering a wide range of evolutionary status and measured their Na, O and Fe\ncontent. We found [Fe/H]=+0.42$\\pm 0.01$, in good agreement with previous\nvalues, and no evidence for a spread. However, the Na:O distribution is\ncompletely unprecedented. It becomes the first open cluster to show intrinsic\nabundance variations that cannot be explained by mixing, and thus the first\ndiscovered to host multiple populations. It is also the first star cluster to\nexhibit two subpopulations in the Na:O diagram with one being chemically\nhomogeneous while the second has an intrinsic spread that follows the\nanticorrelation so far displayed only by globular clusters. NGC 6791 is unique\nin many aspects, displaying certain characteristics typical of open clusters,\nothers more reminiscent of globulars, and yet others, in particular its Na:O\nbehavior investigated here, that are totally unprecedented. It clearly had a\ncomplex and fascinating history." }, { "anchor": "High-redshift rotation curves and MOND: Genzel et al. have recently published the rotation curves of six\nhigh-redshift disc galaxies ($z\\sim 0.9-2.4$), which they find to be `baryon\ndominated' within the studies radii. While not up to the standard afforded by\ndata available for analysis in the nearby Universe, these data are valuable in\nconstraining cosmological evolution of either DM scenarios, or -- as I discuss\nhere -- $z$-dependence of MOND. Indeed, these results, if taken at face value,\nteach us useful lessons in connection with MOND. a. The dynamical accelerations\nat the half-light radii, found by Genzel et al., are rather high compared with\nthe MOND acceleration constant, as measured in the nearby Universe:\n$g(R_{1/2})= (3-11)a_0$. MOND then predicts fractions of `phantom matter' at\n$R_{1/2}$ of at most a few tens of percents, which, galaxy by galaxy, agree\nwell with what Genzel et al. find. b. The asymptotic rotational speeds\npredicted by MOND from the baryonic-mass estimates of Genzel et al. are\nsubstantially lower ($0.55-0.75$) than the maximal speeds of the RCs. MOND thus\npredicts a substantial decline of the RCs beyond the maximum. This too is in\nline with what Genzel et al. find. c. Arguably, the most important lesson is\nthat the findings of Genzel et al. cast very meaningful constraints on possible\nvariation of $a_0$ with cosmic time. For example, they all but exclude a value\nof the MOND constant of $\\sim 4a_0$ at $z\\sim 2$, excluding, e.g., $a_0\\propto\n(1+z)^{3/2}$.", "positive": "Active Galactic Nuclei with a Low-Metallicity Narrow-Line Region: Low-metallicity active galactic nuclei (AGNs) are interesting to study the\nearly phase of the AGN evolution. However most AGNs are chemically matured and\naccordingly low-metallicity AGNs are extremely rare. One approach to search for\nlow-metallicity AGNs systematically is utilizing the so-called BPT diagram that\nconsists of the [O III]$\\lambda$5007/H$\\beta$$\\lambda4861$ and [N\nII]$\\lambda6584$/H$\\alpha$$\\lambda6563$ flux ratios. Specifically,\nphotoionization models predict that low-metallicity AGNs show a high [O\nIII]$\\lambda$5007/H$\\beta$$\\lambda$4861 ratio and a relatively low [N\nII]$\\lambda$6584/H$\\alpha$$\\lambda$6563 ratio, that corresponds to the location\nbetween the sequence of star-forming galaxies and that of usual AGNs on the BPT\ndiagram (hereafter \"the BPT valley\"). However, other populations of galaxies\nsuch as star-forming galaxies and AGNs with a high electron density or a high\nionization parameter could be also located in the BPT valley, not only\nlow-metallicity AGNs. In this paper, we examine whether most of emission-line\ngalaxies at the BPT valley are low-metallicity AGNs or not. We select 70\nBPT-valley objects from 212,866 emission line galaxies obtained by the Sloan\nDigital Sky Survey. Among the 70 BPT-valley objects, 43 objects show firm\nevidence of the AGN activity; i.e., the He II$\\lambda$4686 emission and/or weak\nbut significant broad H$\\alpha$ emission. Our analysis shows that those 43\nBPT-valley AGNs are not characterized by a very high gas density nor ionization\nparameter, inferring that at least 43 among 70 BPT-valley objects (i.e., $>60$\n%) are low-metallicity AGNs. This suggests that the BPT diagram is an efficient\ntool to search for low-metallicity AGNs." }, { "anchor": "AstroSat UVIT Detections of Chandra X-ray Sources in M31: An ultraviolet survey of M31 has been carried out during 2017-19 with the\nUVIT instrument onboard the AstroSat Observatory. Here we match the M31 UVIT\nsource catalog (Leahy et al. 2020) with the Chandra source catalog (Vulic et\nal. 2016). We find 67 UVIT/Chandra sources detected in a varying number of UV\nand X-ray bands. The UV and X-ray photometry is analyzed using powerlaw and\nblackbody models. The X-ray types include 15 LMXBs and 5 AGNs. Cross-matches\nwith catalogs of stars, clusters and other source types yield the following. 20\nof the UVIT/Chandra sources match with M31 globular clusters and 9 with\nforeground stars. 3 more globular clusters and 2 more foreground stars are\nconsistent with the UVIT source positions although outside the Chandra match\nradius of 1 arcsec. The UV emission of the UVIT/Chandra sources associated with\nglobular clusters is consistent with emission from blue horizontal branch stars\nrather than from the X-ray source. The LMXBs in globular clusters are among the\nmost luminous globular clusters in M31.Comparison with stellar evolutionary\ntracks shows that the UVIT/Chandra sources with high UV blackbody temperatures\nare consistent with massive (10 to 30 M$_{\\odot}$) stars in M31.", "positive": "Scalar Field (Wave) Dark Matter: Recent high-quality observations of dwarf and low surface brightness (LSB)\ngalaxies have shown that their dark matter (DM) halos prefer flat central\ndensity profiles. On the other hand the standard cold dark matter model\nsimulations predict a more cuspy behavior. Feedback from star formation has\nbeen widely used to reconcile simulations with observations, this might be\nsuccessful in field dwarf galaxies but its success in low mass galaxies remains\nuncertain. One model that have received much attention is the scalar field dark\nmatter model. Here the dark matter is a self-interacting ultra light scalar\nfield that forms a cosmological Bose-Einstein condensate, a mass of\n$10^{-22}$eV/c$^2$ is consistent with flat density profiles in the centers of\ndwarf spheroidal galaxies, reduces the abundance of small halos, might account\nfor the rotation curves even to large radii in spiral galaxies and has an early\ngalaxy formation. The next generation of telescopes will provide better\nconstraints to the model that will help to distinguish this particular\nalternative to the standard model of cosmology shedding light into the nature\nof the mysterious dark matter." }, { "anchor": "Progress towards a universal family of UV-IR extinction laws: We present our progress on the study of extinction laws along three diferent\nlines. [a] We compare how well different families of extinction laws fit\nexisting photometric data for Galactic sightlines and we find that the Ma\\'iz\nApell\\'aniz et al. (2014) family provides better results than those of Cardelli\net al. (1989) or Fitzpatrick (1999). [b] We describe the HST/STIS\nspectrophotometry in the 1700-10 200 Angstrom range that we are obtaining for\nseveral tens of sightlines in 30 Doradus with the purpose of deriving an\nimproved wavelength-detailed family of extinction laws. [c] We present the\nstudy we are conducting on the behavior of the extinction law in the infrared\nby combining 2MASS and WISE photometry with Spitzer and ISO spectrophotometry.", "positive": "Fast Outflows and Luminous He II Emission in Dwarf Galaxies with AGN: While stellar processes are believed to be the main source of feedback in\ndwarf galaxies, the accumulating discoveries of AGN in dwarf galaxies over\nrecent years arouse the interest to also consider AGN feedback in them. Fast,\nAGN-driven outflows, a major mechanism of AGN feedback, have indeed been\ndiscovered in dwarf galaxies and may be powerful enough to provide feedback to\ntheir dwarf hosts. In this paper, we search for outflows traced by the\nblueshifted ultraviolet absorption features in three dwarf galaxies with AGN\nfrom the sample examined in our previous ground-based study. We confirm\noutflows traced by blueshifted absorption features in two objects and\ntentatively detect an outflow in the third object. In one object where the\noutflow is clearly detected in multiple species, photoionization modeling\nsuggests that this outflow is located $\\sim$0.5 kpc from the AGN, implying a\ngalactic-scale impact. This outflow is much faster and possesses higher kinetic\nenergy outflow rate than starburst-driven outflows in sources with similar star\nformation rates, and is likely energetic enough to provide negative feedback to\nits host galaxy as predicted by simulations. Much broader ($\\sim$4000 km\ns$^{-1}$) absorption features are also discovered in this object which may have\nthe same origin as that of broad absorption lines in quasars. Additionally,\nstrong He II $\\lambda$1640 emission is detected in both objects where the\ntransition falls in the wavelength coverage, and is consistent with an AGN\norigin. In one of these two objects, blueshifted He II emission line is clearly\ndetected, likely tracing a highly-ionized AGN wind." }, { "anchor": "Photometric metallicity for 694233 Galactic giant stars from Gaia DR3\n synthetic Stromgren photometry. Metallicity distribution functions of halo\n sub-structures: We use the calibrations by Calamida et al. and by Hilker et al., and the\nstandardised synthetic photometry in the v, b, and y Stromgren passbands from\nGaia DR3 BP/RP spectra, to obtain photometric metallicities for a selected\nsample of 694233 old Galactic giant stars having |b|>20.0 and parallax\nuncertainties lower than 10%. The zero point of both sets of photometric\nmetallicities has been shifted to to ensure optimal match with the\nspectroscopic [Fe/H] values for 44785 stars in common with APOGEE DR17,\nfocusing on the metallicity range where they provide the highest accuracy. The\nmetallicities derived in this way from the Calamida et al. calibration display\na typical accuracy of ~0.1 dex and 1 sigma precision ~0.2 dex in the range -2.2\n<=[Fe/H]<= -0.4, while they show a systematic trend with [Fe/H] at higher\nmetallicity, beyond the applicability range of the relation. Those derived from\nthe Hilker et al. calibration display, in general, worse precision, and lower\naccuracy in the metal-poor regime, but have a median accuracy < 0.05 dex for\n[Fe/H]>= -0.8. These results are confirmed and, consequently, the metallicities\nvalidated, by comparison with large sets of spectroscopic metallicities from\nvarious surveys. The newly obtained metallicities are used to derive\nmetallicity distributions for several previously identified sub-structures in\nthe Galactic halo with an unprecedented number of stars. The catalogue\nincluding both sets of metallicities and the associated uncertainties is made\npublicly available.", "positive": "Evolution of neutron capture elements in dwarf galaxies: We study the evolution of Eu and Ba abundances in local group dwarf\nspheroidal and ultra faint dwarf galaxies by means of detailed chemical\nevolution models and compare our results with new sets of homogeneous\nabundances. The adopted models include gas infall and outflow and have been\npreviously tested. We investigate several production scenarios for r-process\nelements: merging neutron stars and magneto-rotational driven supernovae.\nProduction of Ba through the main s-process acting in low- and intermediate-\nmass stars is considered as well. We also test different sets of\nnucleosynthesis yields. For merging neutron stars we adopt either a constant\nand short delay time for merging or a delay time distribution function. Our\nsimulations show that: i) if r-process elements are produced only by a quick\nsource, it is possible to reproduce the [Eu/Fe] vs [Fe/H], but those models\nfail in reproducing the [Ba/Fe] vs [Fe/H]. ii) If r-process elements are\nproduced only with longer delays the opposite happens. iii) If both a quick\nsource and a delayed one are adopted, such as magneto-rotational driven\nsupernovae and merging neutron stars with a delay time distribution, the\n[Eu/Fe] abundance pattern is successfully reproduced, but models still fail in\nreproducing the [Ba/Fe]. iv) On the other hand, the characteristic abundances\nof Reticulum II can be reproduced only if both the Eu and the r-process\nfraction of Ba are produced on short and constant time delays during a single\nmerging event. We discuss also other possible interpretations, including an\ninhomogeneous mixing of gas which might characterize this galaxy." }, { "anchor": "Mass segregation in the diffuse outer-halo globular cluster Palomar 14: We present an analysis of the radial dependence of the stellar mass function\nin the diffuse outer-halo globular cluster Palomar 14. Using archival HST/WFPC2\ndata of the cluster's central 39 pc (corresponding to ~0.85*r_h) we find that\nthe mass function in the mass range of 0.55 to 0.85 solar masses is well\napproximated by a power-law at all radii. The mass function steepens with\nincreasing radius, from a shallow power-law slope of 0.66+/-0.32 in the\ncluster's centre to a slope of 1.61+/-0.33 beyond the core radius, showing that\nthe cluster is mass-segregated. This is seemingly in conflict with its long\npresent-day half-mass relaxation time of ~20 Gyr, and with the recent finding\nby Beccari et al. (2011), who interpret the cluster's non-concentrated\npopulation of blue straggler stars as evidence that dynamical segregation has\nnot affected the cluster yet. We discuss this apparent conflict and argue that\nthe cluster must have either formed with primordial mass segregation, or that\nits relaxation time scale must have been much smaller in the past, i.e. that\nthe cluster must have undergone a significant expansion.", "positive": "Chemical Evolution on the Scale of Clusters of Galaxies: A Conundrum?: The metal content of clusters of galaxies and its relation to their stellar\ncontent is revisited making use of a cluster sample for which all four basic\nparameters are homogeneously measured within consistent radii, namely\ncore-excised mass-weighted metallicity plus total, stellar and ICM masses. For\nclusters of total mass $M_{500} >$ $\\sim 10^{14}$ $M_{\\odot}$ nice agreement is\nfound between their iron content and what expected from empirical supernova\nyields. For the same clusters, there also appears to be at least as much iron\nin the intracluster medium (ICM) as there is still locked into stars (i.e., the\nICM/stars metal share is about unity). However, for more massive clusters the\nstellar mass fraction appears to drop substantially without being accompanied\nby a drop in the ICM metallicity, thus generating a major tension with the\nnucleosynthesis expectation and inflating the metal share to extremely high\nvalues (up to $\\sim 6$). Various possible solutions of this conundrum are\ndiscussed, but are all considered either astrophysically implausible, or\nlacking an independent observational support. For this reason we still\nentertain the possibility that even some of the best cluster data may be\nfaulty, though we are not able to identify any obvious bias. Finally, based on\nthe stellar mass-metallicity relation for local galaxies we estimate the\ncontribution of galaxies to the ICM enrichment as a function of their mass,\nconcluding that even the most massive galaxies must have lost a major fraction\nof the metals they have produced." }, { "anchor": "Flow of gas detected from beyond the filaments to protostellar scales in\n Barnard 5: The infall of gas from outside natal cores has proven to feed protostars\nafter the main accretion phase (Class 0). This changes our view of star\nformation to a picture that includes asymmetric accretion (streamers), and a\nlarger role of the environment. However, the connection between streamers and\nthe filaments that prevail in star-forming regions is unknown. We investigate\nthe flow of material toward the filaments within Barnard 5 (B5) and the infall\nfrom the envelope to the protostellar disk of the embedded protostar B5-IRS1.\nOur goal is to follow the flow of material from the larger, dense core scale,\nto the protostellar disk scale. We present new HC$_3$N line data from the NOEMA\nand 30m telescopes covering the coherence zone of B5, together with ALMA\nH$_2$CO and C$^{18}$O maps toward the protostellar envelope. We fit multiple\nGaussian components to the lines so as to decompose their individual physical\ncomponents. We investigate the HC$_3$N velocity gradients to determine the\ndirection of chemically-fresh gas flow. At envelope scales, we use a clustering\nalgorithm to disentangle the different kinematic components within H$_2$CO\nemission. At dense core scales, HC$_3$N traces the infall from the B5 region\ntoward the filaments. HC$_3$N velocity gradients are consistent with accretion\ntoward the filament spines plus flow along them. We found a $\\sim2800$ au\nstreamer in H$_2$CO emission which is blueshifted with respect to the protostar\nand deposits gas at outer disk scales. The strongest velocity gradients at\nlarge scales curve toward the position of the streamer at small scales,\nsuggesting a connection between both flows. Our analysis suggests that the gas\ncan flow from the dense core to the protostar. This implies that the mass\navailable for a protostar is not limited to its envelope, and can receiving\nchemically-unprocessed gas after the main accretion phase.", "positive": "The CHESS survey of the L1157-B1 shock: the dissociative jet shock as\n revealed by Herschel--PACS: Outflows generated by protostars heavily affect the kinematics and chemistry\nof the hosting molecular cloud through strong shocks that enhance the abundance\nof some molecules. L1157 is the prototype of chemically active outflows, and a\nstrong shock, called B1, is taking place in its blue lobe between the\nprecessing jet and the hosting cloud. We present the Herschel-PACS 55--210\nmicron spectra of the L1157-B1 shock, showing emission lines from CO, H2O, OH,\nand [OI]. The spatial resolution of the PACS spectrometer allows us to map the\nwarm gas traced by far-infrared (FIR) lines with unprecedented detail. The\nrotational diagram of the high-Jup CO lines indicates high-excitation\nconditions (Tex ~ 210 +/- 10 K). We used a radiative transfer code to model the\nhot CO gas emission observed with PACS and in the CO (13-12) and (10-9) lines\nmeasured by Herschel-HIFI. We derive 20010^5 cm-3. The CO\nemission comes from a region of about 7 arcsec located at the rear of the bow\nshock where the [OI] and OH emission also originate. Comparison with shock\nmodels shows that the bright [OI] and OH emissions trace a dissociative J-type\nshock, which is also supported by a previous detection of [FeII] at the same\nposition. The inferred mass-flux is consistent with the \"reverse\" shock where\nthe jet is impacting on the L1157-B1 bow shock. The same shock may contribute\nsignificantly to the high-Jup CO emission." }, { "anchor": "Abundance analysis of the outer halo globular cluster Palomar 14: We determine the elemental abundances of nine red giant stars belonging to\nPalomar 14 (Pal 14). Pal 14 is an outer halo globular cluster (GC) at a\ndistance of \\sim 70 kpc. Our abundance analysis is based on high-resolution\nspectra and one-dimensional stellar model atmospheres.We derived the abundances\nfor the iron peak elements Sc, V, Cr, Mn, Co, Ni, the {\\alpha}-elements O, Mg,\nSi, Ca, Ti, the light odd element Na, and the neutron-capture elements Y, Zr,\nBa, La, Ce, Nd, Eu, Dy, and Cu. Our data do not permit us to investigate light\nelement (i.e., O to Mg) abundance variations. The neutron-capture elements show\nan r-process signature. We compare our measurements with the abundance ratios\nof inner and other outer halo GCs, halo field stars, GCs of recognized\nextragalactic origin, and stars in dwarf spheroidal galaxies (dSphs). The\nabundance pattern of Pal 14 is almost identical to those of Pal 3 and Pal 4,\nthe next distant members of the outer halo GC population after Pal 14. The\nabundance pattern of Pal 14 is also similar to those of the inner halo GCs,\nhalo field stars, and GCs of recognized extragalactic origin, but differs from\nwhat is customarily found in dSphs field stars. The abundance properties of Pal\n14 as well as those of the other outer halo GCs are thus compatible with an\naccretion origin from dSphs. Whether or not GC accretion played a role, it\nseems that the formation conditions of outer halo GCs and GCs in dSphs were\nsimilar.", "positive": "Unusual Infrared Emission toward Sgr B2: Possible Planar C$_{24}$: Interstellar graphene could be present in the interstellar medium (ISM),\nresulting from the photochemical processing of polycyclic aromatic hydrocarbon\n(PAH) molecules and/or collisional fragmentation of graphitic particles.\nIndeed, by comparing the observed ultraviolet (UV) extinction and infrared (IR)\nemission of the diffuse ISM with that predicted for graphene, as much as $\\sim$\n2% of the total interstellar carbon could have been locked up in graphene\nwithout violating the observational constraints. While the possible detection\nof planar C$_{24}$, a small piece of a graphene sheet, has been reported\ntowards several Galactic and extragalactic planetary nebulae, graphene has not\nyet been detected in interstellar environments. In this work, we search for the\ncharacteristic IR features of C$_{24}$ at $\\sim$ 6.6, 9.8, 20 $\\mu m$ toward\nSgr B2, a high-mass star formation region, and find a candidate target toward\nR.A. (J2000) = $267^{\\circ}.05855$ and Decl. (J2000) = $-28^{\\circ}.01479$ in\nSgr B2 whose Spitzer/IRS spectra exhibit three bands peaking at $\\sim$ 6.637,\n9.853 and 20.050 $\\mu m$ which appear to be coincident with that of C$_{24}$.\nPossible features of C$_{60}$ are also seen in this region. The candidate\nregion is a warm dust environment heated by massive stars or star clusters,\nassociated with a WISE spot (a tracer of star-formation activity), close to the\nHII region candidate IRAS 17450-2759, and is surrounded by seven young stellar\nobject candidates within $\\sim$ 5$^{\\prime}$, suggesting that the creation\nand/or excitation of C$_{24}$ could be related to star formation activities." }, { "anchor": "The effect of gas accretion on the radial gas metallicity profile of\n simulated galaxies: We study the effect of the gas accretion rate ($\\dot M_{\\rm accr}$) on the\nradial gas metallicity profile (RMP) of galaxies using the EAGLE cosmological\nhydrodynamic simulations, focusing on central galaxies of stellar mass $M_\\star\n\\gtrsim 10^9 \\, {\\rm M_\\odot}$ at $z \\le 1$. We find clear relations between\n$\\dot M_{\\rm accr}$ and the slope of the RMP (measured within an effective\nradius), where higher $\\dot M_{\\rm accr}$ are associated with more negative\nslopes. The slope of the RMPs depends more strongly on $\\dot M_{\\rm accr}$ than\non stellar mass, star formation rate or gas fraction, suggesting $\\dot M_{\\rm\naccr}$ to be a more fundamental driver of the RMP slope of galaxies. We find\nthat eliminating the dependence on stellar mass is essential for pinning down\nthe properties that shape the slope of the RMP. Although $\\dot M_{\\rm accr}$ is\nthe main property modulating the slope of the RMP, we find that it causes other\ncorrelations that are more easily testable observationally: at fixed stellar\nmass, galaxies with more negative RMP slopes tend to have higher gas fractions\nand SFRs, while galaxies with lower gas fractions and SFRs tend to have flatter\nmetallicity profiles within an effective radius.", "positive": "Advanced Diagnostics for the Study of Linearly Polarized Emission. I:\n Derivation: Linearly polarized emission is described, in general, in terms of the Stokes\nparameters $Q$ and $U$, from which the polarization intensity and polarization\nangle can be determined. Although the polarization intensity and polarization\nangle provide an intuitive description of the polarization, they are affected\nby the limitations of interferometric data, such as missing single-dish data in\nthe u-v plane, from which radio frequency interferometric data is visualized.\nTo negate the effects of these artefacts, it is desirable for polarization\ndiagnostics to be rotationally and translationally invariant in the $Q$-$U$\nplane. One rotationally and translationally invariant quantity, the\npolarization gradient, has been shown to provide a unique view of spatial\nvariations in the turbulent interstellar medium when applied to diffuse radio\nfrequency synchrotron emission. In this paper we develop a formalism to derive\nadditional rotationally and translationally invariant quantities. We present\nnew diagnostics that can be applied to diffuse or point-like polarized emission\nin any waveband, including a generalization of the polarization gradient, the\npolarization directional curvature, polarization wavelength derivative, and\npolarization wavelength curvature. In Paper II we will apply these diagnostics\nto observed and simulated images of diffuse radio frequency synchrotron\nemission." }, { "anchor": "The Black Hole Mass - Galaxy Luminosity Relationship for Sloan Digital\n Sky Survey Quasars: We investigate the relationship between the mass of the central supermassive\nblack hole, M_bh, and the host galaxy luminosity, L_gal, in a sample of quasars\nfrom the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We use composite\nquasar spectra binned by black hole mass and redshift to assess galaxy features\nthat would otherwise be overwhelmed by noise in individual spectra. The black\nhole mass is calculated using the photoionization method, and the host galaxy\nluminosity is inferred from the depth of the Ca II H + K features in the\ncomposite spectra. We evaluate the evolution in the M_bh - L_gal relationship\nby examining the redshift dependence of Delta log M_bh, the offset in black\nhole mass from the local black hole - bulge relationship. There is little\nsystematic trend in Delta log M_bh out to z = 0.8. Using the width of the [O\nIII] emission line as a proxy for the stellar velocity dispersion, sigma_*, we\nfind agreement of our derived host luminosities with the locally-observed\nFaber-Jackson relation. This supports the utility of the width of the [O III]\nline as a proxy for sigma_* in statistical studies.", "positive": "Local Swift-BAT active galactic nuclei prefer circumnuclear star\n formation: We use Herschel data to analyze the size of the far-infrared 70micron\nemission for z<0.06 local samples of 277 hosts of Swift-BAT selected active\ngalactic nuclei (AGN), and 515 comparison galaxies that are not detected by\nBAT. For modest far-infrared luminosities 8.510.5 (star formation\nrates >~ 6 Msun/yr), possibly because these are typically reached in more\ncompact regions in the first place." }, { "anchor": "A Catalog of 71 Coronal Line Galaxies in MaNGA: [NeV] is an Effective\n AGN Tracer: Despite the importance of AGN in galaxy evolution, accurate AGN\nidentification is often challenging, as common AGN diagnostics can be confused\nby contributions from star formation and other effects (e.g.,\nBaldwin-Phillips-Terlevich diagrams). However, one promising avenue for\nidentifying AGNs are ``coronal emission lines\" (``CLs\"), which are highly\nionized species of gas with ionization potentials $\\ge$ 100 eV. These CLs may\nserve as excellent signatures for the strong ionizing continuum of AGN. To\ndetermine if CLs are in fact strong AGN tracers, we assemble and analyze the\nlargest catalog of optical CL galaxies using the Sloan Digital Sky Survey's\nMapping Nearby Galaxies at Apache Point Observatory (MaNGA) catalog. We detect\nCL emission in 71 MaNGA galaxies, out of the 10,010 unique galaxies from the\nfinal MaNGA catalog, with $\\ge$ 5$\\sigma$ confidence. In our sample, we measure\n[NeV]$\\lambda$3347, $\\lambda$3427, [FeVII]$\\lambda$3586, $\\lambda$3760,\n$\\lambda$6086, and [FeX]$\\lambda$6374 emission and crossmatch the CL galaxies\nwith a catalog of AGNs that were confirmed with broad line, X-ray, IR, and\nradio observations. We find that [NeV] emission, compared to [FeVII] and [FeX]\nemission, is best at identifying high luminosity AGN. Moreover, we find that\nthe CL galaxies with the least dust extinction yield the most iron CL\ndetections. We posit that the bulk of the iron CLs are destroyed by dust grains\nin the galaxies with the highest [OIII] luminosities in our sample, and that\nAGN in the galaxies with low [OIII] luminosities are possibly too weak to be\ndetected using traditional techniques.", "positive": "Discordant optical and X-ray classification of AGN: To provide insight into the apparent mismatch between the optical and X-ray\nabsorption properties observed in 10-30 % of Active Galactic Nuclei (AGN), we\nhave conducted a detailed study of two X-ray unabsorbed AGN with a type-2\noptical spectroscopic classification. In addition to high quality X-ray\nspectroscopic observations, that we used to determine both the AGN luminosities\nand absorption, we have a VLT/XSHOOTER UV-to-near-IR high resolution spectrum\nfor each object, that we used to determine the AGN intrinsic emision corrected\nfor both contamination from the AGN hosts and extinction. Our analysis has\nrevealed that the apparent mismatch is provoked by galaxy dilution. We dilution\nof two AGN with extreme properties: one of them has an intrinsically very high\nBalmer decrement while the other lies in a galaxy more massive than expected." }, { "anchor": "Evidence of bimodal physical properties of intervening, optically-thin\n CIII absorbers at z ~ 2.5: We present the Voigt profile analysis of 132 intervening CIV+CIII components\nassociated with optically-thin HI absorbers at 2.1 < z < 3.4 in the 19\nhigh-quality UVES/VLT and HIRES/Keck QSO spectra. For log N(CIV) = [11.7,\n14.1], N(CIII) is proportional to N(CIV) with an exponent (1.42 +- 0.11) and <\nN(CIII)/N(CIV) > = 1.0 +- 0.3 with a negligible redshift evolution. For 54 CIV\ncomponents tied (aligned) with HI at log N(HI) = [12.2, 16.0] and log N(CIV) =\n[11.8, 13.8], the gas temperature T_b estimated from absorption line widths is\nwell-approximated to a Gaussian peaking at log T_b ~ 4.4 +- 0.3 for log T_b =\n[3.5, 5.5], with a negligible non-thermal contribution. For 32 of 54 tied\nHI+CIV pairs, also tied with CIII at log N(CIII) = [11.7, 13.8], we ran both\nphotoionisation equilibrium (PIE) and non-PIE (using a fixed temperature T_b)\nCloudy models for the Haardt-Madau QSO+galaxy 2012 UV background. We find\nevidence of bimodality in observed and derived physical properties.\nHigh-metallicity branch absorbers have a carbon abundance [C/H]_temp > -1.0, a\nline-of-sight length L_temp < 20 kpc, and a total (neutral and ionised)\nhydrogen volume density log n(H, temp) = [-4.5, -3.3] and and log T_b = [3.9,\n4.5]. Low-metallicity branch absorbers have [C/H]_temp < -1.0, L_temp = [20,\n480] kpc and log n(H, temp) = [-5.2, -4.3] and log T_b ~ 4.5. High-metallicity\nbranch absorbers seem to be originated from extended disks, inner halos or\noutflowing gas of intervening galaxies, while low-metallicity absorbers are\nproduced by galactic halos or the surrounding IGM filament.", "positive": "EMPRESS. IV. Extremely Metal-Poor Galaxies (EMPGs) Including Very\n Low-Mass Primordial Systems with M*=10^4--10^5 M_sun and 2--3% (O/H)_sun:\n High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-Instability\n Supernovae: We present Keck/LRIS follow-up spectroscopy for 13 photometric candidates of\nextremely metal poor galaxies (EMPGs) selected by a machine-learning technique\napplied to the deep (~26 AB mag) optical and wide-area (~500 deg^2) Subaru\nimaging data in the EMPRESS survey. Nine out of the 13 candidates are EMPGs\nwith an oxygen abundance (O/H) less than ~10% solar value (O/H)_sun, and four\nsources are contaminants of moderately metal-rich galaxies or no emission-line\nobjects. Notably, two out of the nine EMPGs have extremely-low stellar masses\nand oxygen abundances of 5*10^4--7*10^5 M_sun and 2--3% (O/H)_sun,\nrespectively. With a sample of five EMPGs with (Fe/O) measurements, two (three)\nof which are taken from this study (the literature), we confirm that two EMPGs\nwith the lowest (O/H) ratios of ~2% (O/H)_sun show high (Fe/O) ratios of ~0.1,\nclose to the solar abundance ratio. Comparing galaxy chemical enrichment\nmodels, we find that the two EMPGs cannot be explained by a scenario of\nmetal-poor gas accretion/episodic star-formation history due to their low (N/O)\nratios. We conclude that the two EMPGs can be reproduced by an inclusion of\nbright hypernovae and/or hypothetical pair-instability supernovae (SNe)\npreferentially produced in a metal-poor environment. This conclusion implies\nthat primordial galaxies at z~10 could have a high abundance of Fe that is not\noriginated from Type Ia SNe with delays, and that Fe may not serve as a cosmic\nclock for primordial galaxies." }, { "anchor": "Long-term orbital evolution of Galactic satellites and the effects on\n their star formation histories: We investigate the orbital motions of dwarf spheroidal galaxies (dSphs) in\nthe halo of the Milky Way (MW) to understand their possible effects on the\ndiversity of the star formation histories seen in these MW satellites. In this\nwork, we explicitly consider a time-varying gravitational potential due to the\ngrowth of the MW's dark halo mass to calculate the long-term orbital evolutions\nof the dSphs, guided with {\\it Gaia} DR2 proper motions, over the past 13.5\nbillion years. We find that the infall time of a satellite, defined at which\nthe galaxy first crosses within the growing virial radius of the MW's halo,\ncoincides well with the time when the star formation rate (SFR) is peaked for\nthe sample of classical dSphs. On the other hand, ultra-faint dSphs already\nfinished their SF activity prior to their infall times as already suggested in\nprevious works, but there is a signature that their earlier SF histories are\naffected by interaction with the growing MW's halo to some extent. We also\nfind, for classical dSphs, that the relative fraction of stars formed after the\npeak of the SFR to the current stellar mass is smaller for the smaller\npericentric radius of the galaxy at its first infall. These results suggest\nthat the infalling properties of the dSphs into the MW and the resultant\nenvironmental effects such as ram-pressure stripping and/or tidal disturbance\nin the MW's dark halo containing hot gas play important roles in their star\nformation histories.", "positive": "Physical Properties of Molecular Clouds at 2 parsec Resolution in the\n Low-Metallicity Dwarf Galaxy NGC 6822 and the Milky Way: We present the ALMA survey of CO(2-1) emission from the 1/5 solar\nmetallicity, Local Group dwarf galaxy NGC 6822. We achieve high (0.9 arcsec ~ 2\npc) spatial resolution while covering large area: four 250 pc x 250 pc regions\nthat encompass ~2/3 of NGC 6822's star formation. In these regions, we resolve\n~150 compact CO clumps that have small radii (~2-3 pc), narrow line width (~1\nkm/s), and low filling factor across the galaxy. This is consistent with other\nrecent studies of low metallicity galaxies, but here shown with a 15 times\nlarger sample. At parsec scales, CO emission correlates with 8 micron emission\nbetter than with 24 micron emission and anti-correlates with Halpha, so that\nPAH emission may be an effective tracer of molecular gas at low metallicity.\nThe properties of the CO clumps resemble those of similar-size structures in\nGalactic clouds except of slightly lower surface brightness and CO-to-H2 ratio\n~1-2 times the Galactic value. The clumps exist inside larger atomic-molecular\ncomplexes with masses typical for giant molecular cloud. Using dust to trace H2\nfor the entire complex, we find CO-to-H2 to be ~20-25 times the Galactic value,\nbut with strong dependence on spatial scale and variations between complexes\nthat may track their evolutionary state. The H2-to-HI ratio is low globally and\nonly mildly above unity within the complexes. The SFR-to-H2 ratio is ~3-5 times\nhigher in the complexes than in massive disk galaxies, but after accounting for\nthe bias from targeting star-forming regions, we conclude that the global\nmolecular gas depletion time may be as long as in massive disk galaxies." }, { "anchor": "VEGAS: A VST Early-type GAlaxy Survey. II. Photometric study of giant\n ellipticals and their stellar halos: Observations of diffuse starlight in the outskirts of galaxies are thought to\nbe a fundamental source of constraints on the cosmological context of galaxy\nassembly in the $\\Lambda$CDM model. Such observations are not trivial because\nof the extreme faintness of such regions. In this work, we investigate the\nphotometric properties of six massive early type galaxies (ETGs) in the VEGAS\nsample (NGC 1399, NGC 3923, NGC 4365, NGC 4472, NGC 5044, and NGC 5846) out to\nextremely low surface brightness levels, with the goal of characterizing the\nglobal structure of their light profiles for comparison to state-of-the-art\ngalaxy formation models. We carry out deep and detailed photometric mapping of\nour ETG sample taking advantage of deep imaging with VST/OmegaCAM in the g and\ni bands. By fitting the light profiles, and comparing the results to\nsimulations of elliptical galaxy assembly, we identify signatures of a\ntransition between \"relaxed\" and \"unrelaxed\" accreted components and can\nconstrain the balance between in situ and accreted stars. The very good\nagreement of our results with predictions from theoretical simulations\ndemonstrates that the full VEGAS sample of $\\sim 100$ ETGs will allow us to use\nthe distribution of diffuse light as a robust statistical probe of the\nhierarchical assembly of massive galaxies.", "positive": "SNR 0104-72.3: A remnant of Type Ia Supernova in a Star-forming region?: We report our 110 ks Chandra observations of the supernova remnant (SNR)\n0104-72.3 in the Small Magellanic Cloud (SMC). The X-ray morphology shows two\nprominent lobes along the northwest-southeast direction and a soft faint arc in\nthe east. Previous low resolution X-ray images attributed the unresolved\nemission from the southeastern lobe to a Be/X-ray star. Our high resolution\nChandra data clearly shows that this emission is diffuse, shock-heated plasma,\nwith negligible X-ray emission from the Be star. The eastern arc is\npositionally coincident with a filament seen in optical and infrared\nobservations. Its X-ray spectrum is well fit by plasma of normal SMC\nabundances, suggesting that it is from shocked ambient gas. The X-ray spectra\nof the lobes show overabundant Fe, which is interpreted as emission from the\nreverse-shocked Fe-rich ejecta. The overall spectral characteristics of the\nlobes and the arc are similar to those of Type Ia SNRs, and we propose that SNR\n0104-72.3 is the first case for a robust candidate Type Ia SNR in the SMC. On\nthe other hand, the remnant appears to be interacting with dense clouds toward\nthe east and to be associated with a nearby star-forming region. These features\nare unusual for a standard Type Ia SNR. Our results suggest an intriguing\npossibility that the progenitor of SNR 0104-72.3 might have been a white dwarf\nof a relatively young population." }, { "anchor": "Interferometric mapping of magnetic fields: The ALMA view of the massive\n star forming clump W43-MM1: Here we present the first results from ALMA observations of 1 mm polarized\ndust emission towards the W43-MM1 high mass star forming clump. We have\ndetected a highly fragmented filament with source masses ranging from 14Msun to\n312Msun, where the largest fragment, source A, is believed to be one of the\nmost massive in our Galaxy. We found a smooth, ordered, and detailed\npolarization pattern throughout the filament which we used to derived magnetic\nfield morphologies and strengths for 12 out of the 15 fragments detected\nranging from 0.2 to 9 mG. The dynamical equilibrium of each fragment was\nevaluated finding that all the fragments are in a super-critical state which is\nconsistent with previously detected infalling motions towards W43-MM1.\nMoreover, there are indications suggesting that the field is being dragged by\ngravity as the whole filament is collapsing.", "positive": "Classical and relativistic laws of motion for spherical supernovas: We derive some first order differential equations which model the classical\nand the relativistic thin layer approximations. The circumstellar medium is\nassumed to follow a density profile which can be exponential, Gaussian,\nPlummer-like, self-gravitating of Lane--Emden ($n=5$) type, or power law. The\nfirst order differential equations are solved analytically, or numerically, or\nby a series expansion, or by recursion, or by Pad\\'e approximation. The initial\nconditions are chosen in order to model the temporal evolution of SN 1993J over\nten years. The Pad\\'e approximated equations of motion are applied to four\nSNRs: Tycho, Cas A, Cygnus loop, and SN~1006." }, { "anchor": "On the dominant role of wind in the quasar feedback mode in the late\n stage evolution of massive elliptical galaxies: In this paper we investigate the role of AGN feedback on the late stage\nevolution of elliptical galaxies by performing high-resolution hydrodynamical\nsimulation in the {\\it MACER} framework. By comparing models that take into\naccount different feedback mechanisms, namely AGN and stellar feedback, we find\nthat AGN feedback is crucial in keeping the black hole in a low accretion state\nand suppressing the star formation. We then compare the energy from AGN\nradiation and wind deposited in the galaxy and find that only wind can\ncompensate for the radiative cooling of the gas in the galaxy. Further, we\ninvestigate which plays the dominant role, the wind from the cold (quasar) or\nhot (radio) feedback modes, by examining the cumulative energy output and\nimpact area to which the wind can heat the interstellar medium and suppress\nstar formation. Our results indicate that first, although AGN spends most of\nits time in hot (radio) mode, the cumulative energy output is dominated by the\noutburst of the cold mode. Second, only the impact area of the cold-mode wind\nis large enough to heat the gas in the halo, while the hot-mode wind is not.\nAdditionally, the cold-mode wind is capable of sweeping up the material from\nstellar mass loss. These results indicate the dominant role of cold-mode wind.\nThe limitations of our model, including the absence of jet feedback, are\ndiscussed.", "positive": "The CALYMHA survey: Lya luminosity function and global escape fraction\n of Lya photons at z=2.23: We present the CAlibrating LYMan-$\\alpha$ with H$\\alpha$ (CALYMHA) pilot\nsurvey and new results on Lyman-$\\alpha$ (Lya) selected galaxies at z~2. We use\na custom-built Lya narrow-band filter at the Isaac Newton Telescope, designed\nto provide a matched volume coverage to the z=2.23 Ha HiZELS survey. Here we\npresent the first results for the COSMOS and UDS fields. Our survey currently\nreaches a 3$\\sigma$ line flux limit of ~4x10$^{-17}$ erg/s/cm$^{2}$, and a Lya\nluminosity limit of ~10$^{42.3}$ erg/s. We find 188 Lya emitters over\n7.3x10$^5$ Mpc$^{3}$, but also find significant numbers of other line emitting\nsources corresponding to HeII, CIII] and CIV emission lines. These sources are\nimportant contaminants, and we carefully remove them, unlike most previous\nstudies. We find that the Lya luminosity function at z=2.23 is very well\ndescribed by a Schechter function up to L~10$^{43}$ erg/s with\nL$^*=10^{42.59+-0.05}$ erg/s, $\\phi^*=10^{-3.09+-0.08}$ Mpc$^{-3}$ and\n$\\alpha$=-1.75+-0.15. Above L~10$^{43}$ erg/s the Lya luminosity function\nbecomes power-law like, driven by X-ray AGN. We find that Lya-selected emitters\nhave a high escape fraction of 37+-7%, anti-correlated with Lya luminosity and\ncorrelated with Lya equivalent width. Lya emitters have ubiquitous large (~40\nkpc) Lya haloes, 2x larger than their Ha extents. By directly comparing our Lya\nand Ha luminosity functions we find that the global/overall escape fraction of\nLya photons (within a 13 kpc radius) from the full population of star-forming\ngalaxies is 5.1+-0.2% at the peak of the star formation history. An extra\n3.3+-0.3% of Lya photons likely still escape, but at larger radii." }, { "anchor": "ALLSMOG: an APEX Low-redshift Legacy Survey for MOlecular Gas. I -\n molecular gas scaling relations, and the effect of the CO/H2 conversion\n factor: We present ALLSMOG, the APEX Low-redshift Legacy Survey for MOlecular Gas.\nALLSMOG is a survey designed to observe the CO(2-1) emission line with the APEX\ntelescope, in a sample of local galaxies (0.01 < z < 0.03), with stellar masses\nin the range 8.5 < log(M*/Msun) < 10. This paper is a data release and initial\nanalysis of the first two semesters of observations, consisting of 42 galaxies\nobserved in CO(2-1). By combining these new CO(2-1) emission line data with\narchival HI data and SDSS optical spectroscopy, we compile a sample of low-mass\ngalaxies with well defined molecular gas masses, atomic gas masses, and\ngas-phase metallicities. We explore scaling relations of gas fraction and gas\nconsumption timescale, and test the extent to which our findings are dependent\non a varying CO/H2 conversion factor. We find an increase in the H2/HI mass\nratio with stellar mass which closely matches semi-analytic predictions. We\nfind a mean molecular gas fraction for ALLSMOG galaxies of MH2/M* = (0.09 -\n0.13), which decreases with stellar mass. We measure a mean molecular gas\nconsumption timescale for ALLSMOG galaxies of 0.4 - 0.7 Gyr. We also confirm\nthe non-universality of the molecular gas consumption timescale, which varies\n(with stellar mass) from ~100 Myr to ~2 Gyr. Importantly, we find that the\ntrends in the H2/HI mass ratio, gas fraction, and the non-universal molecular\ngas consumption timescale are all robust to a range of recent\nmetallicity-dependent CO/H2 conversion factors.", "positive": "The Activation of Galactic Nuclei and Their Accretion Rates are Linked\n to the Star Formation Rates and Bulge-types of Their Host Galaxies: We use bulge-type classifications of 809 representative SDSS galaxies by\nGadotti (2009) to classify a large sample of galaxies into real bulges\n(classical or elliptical) and pseudobulges using Random Forest. We use\nstructural and stellar population predictors that can easily be measured\nwithout image decomposition. Multiple parameters such as the central mass\ndensity with 1 kpc, concentration index, S\\'{e}rsic index and velocity\ndispersion do result in accurate bulge classifications when combined together.\nWe classify $\\sim 44,500$ face-on galaxies above stellar mass of 10$^{10}$\nM$_\\odot$ and redshift $ 0.02 < z < 0.07$ into real bulges or pseudobulges with\n$93 \\pm 2$\\% accuracy. We show that $\\sim 75 - 90\\%$ of AGNs identified by the\noptical line ratio diagnostic are hosted by real bulges. The pseudobulge\nfraction significantly decreases with AGN signature as the line ratios change\nfrom indicating pure star formation ($\\sim 54 \\pm 4$ \\%), to composite of star\nformation and AGN ($\\sim 18 \\pm 3$\\%), and to AGN-dominated galaxies ($\\sim 5\n\\pm 3$\\%). Using the dust-corrected [\\ion{O}{3}] luminosity as an AGN accretion\nindicator, and the stellar mass and radius as proxies for a black hole mass, we\nfind that AGNs in real bulges have lower Eddington ratios than AGNs in\npseudobulges. Real bulges have a wide range of AGN and star formation\nactivities, although most of them are weak AGNs. For both bulge-types, their\nEddington ratios are correlated with specific star formation rates (SSFR). Real\nbulges have lower specific accretion rate but higher AGN fraction than\npseudobulges do at similar SSFRs." }, { "anchor": "UM 625 Revisited: Multiwavelength Study of A Seyfert 1 Galaxy with a\n Low-mass Black Hole: UM 625, previously identified as a narrow-line active galactic nucleus (AGN),\nactually exhibits broad \\ha\\ and \\hb\\ lines whose width and luminosity indicate\na low black hole mass of $1.6 \\times 10^6$ \\msun. We present a detailed\nmultiwavelength study of the nuclear and host galaxy properties of UM 625.\nAnalysis of \\chandra\\ and \\xmm\\ observations suggests that this system contains\na heavily absorbed and intrinsically X-ray weak ($\\aox=-1.72$) nucleus.\nAlthough not strong enough to qualify as radio-loud, UM 625 does belong to a\nminority of low-mass AGNs detected in the radio. The broad-band spectral energy\ndistribution constrains the bolometric luminosity to\n$\\lbol\\approx(0.5-3)\\times10^{43}$ \\lum\\ and $\\lratio\\approx0.02-0.15$. A\ncomprehensive analysis of Sloan Digital Sky Survey and {\\it Hubble Space\nTelescope}\\ images shows that UM 625 is a nearly face-on S0 galaxy with a\nprominent, relatively blue pseudobulge (\\sersic\\ index $n = 1.60$) that\naccounts for $\\sim$60% of the total light in the $R$ band. The extended disk is\nfeatureless, but the central $\\sim150-400$ pc contains a conspicuous semi-ring\nof bright, blue star-forming knots, whose integrated ultraviolet luminosity\nsuggests a star formation rate of $\\sim$0.3 \\msun yr$^{-1}$. The mass of the\ncentral black hole roughly agrees with the value predicted from its bulge\nvelocity dispersion but is significantly lower than that expected from its\nbulge luminosity.", "positive": "Wide-Field Hubble Space Telescope Observations of the Globular Cluster\n System in NGC1399: We present a comprehensive high spatial-resolution imaging study of globular\nclusters (GCs) in NGC1399, the central giant elliptical cD galaxy in the Fornax\ngalaxy cluster, conducted with HST/ACS. Using a novel technique to construct\ndrizzled PSF libraries for HST/ACS data, we accurately determine the fidelity\nof GC structural parameter measurements from detailed artificial star cluster\nexperiments. The measurement of rh for the major fraction of the NGC1399 GC\nsystem reveals a trend of increasing rh versus galactocentric distance, Rgal,\nout to about 10 kpc and a flat relation beyond. This trend is very similar for\nblue and red GCs which are found to have a mean size ratio of\nrh(red)/rh(blue)=0.82+/-0.11 at all galactocentric radii from the core regions\nof the galaxy out to ~40 kpc. This suggests that the size difference between\nblue and red GCs is due to internal mechanisms related to the evolution of\ntheir constituent stellar populations. Modeling the mass density profile of\nNGC1399 shows that additional external dynamical mechanisms are required to\nlimit the GC size in the galaxy halo regions to rh~2 pc. We suggest that this\nmay be realized by an exotic GC orbit distribution function, an extended dark\nmatter halo, and/or tidal stress induced by the increased stochasticity in the\ndwarf halo substructure at larger Rgal. We match our GC rh measurements with\nradial velocity data from the literature and find that compact GCs show a\nsignificantly smaller line-of-sight velocity dispersion, =225+/-25\nkm/s, than their extended counterparts, =317+/-21 km/s. Considering\nthe weaker statistical correlation in the GC rh-color and the GC rh-Rgal\nrelations, the more significant GC size-dynamics relation appears to be\nastrophysically more relevant and hints at the dominant influence of the GC\norbit distribution function on the evolution of GC structural parameters." }, { "anchor": "The Effects of Protostellar Jet Feedback on Turbulent Collapse: We present results of hydrodynamic simulations of massive star forming\nregions with and without protostellar jets. We show that jets change the\nnormalization of the stellar mass accretion rate, but do not strongly affect\nthe dynamics of star formation. In particular, $M_*(t) \\propto f^2 (t-t_*)^2$\nwhere $f = 1 - f_{\\rm jet}$ is the fraction of mass accreted onto the\nprotostar, $f_{\\rm jet}$ is the fraction ejected by the jet, and $(t-t_*)^2$ is\nthe time elapsed since the formation of the first star. The star formation\nefficiency is nonlinear in time. We find that jets have only a small effect (of\norder 25\\%) on the accretion rate onto the protostellar disk (the \"raw\"\naccretion rate). We show that the small scale structure -- the radial density,\nvelocity, and mass accretion profiles are very similar in the jet and no-jet\ncases. Finally, we show that the inclusion of jets does drive turbulence but\nonly on small (parsec) scales.", "positive": "The Role of Inner HI Mass in Regulating the Scatter of the\n Mass-Metallicity Relation: We use 789 disk-like, star-forming galaxies (with 596 HI detections) from HI\nfollow-up observations for the SDSS-IV MaNGA survey to study the possible role\nof inner HI gas in causing secondary dependences in the mass-gas-phase\nmetallicity relation. We use the gas-phase metallicity derived at the effective\nradii of the galaxies. We derive the inner HI mass witHIn the optical radius,\nbut also use the total HI mass and star formation rate (SFR) for a comparison.\nWe confirm the anticorrelation between the total HI mass and gas-phase\nmetallicity at fixed stellar mass, but the anticorrelation is significantly\nstrengthened when the total HI mass is replaced by the inner HI mass.\nIntroducing a secondary relation with the inner HI mass can produce a small but\nnoticeable decrease (16%) in the scatter of the mass-gas-phase metallicity\nrelation, in contrast to the negligible effect with the SFR. The correlation\nwith the inner HI mass is robust when using different diagnostics of\nmetallicity, but the correlation with SFR is not. The correlation with the\ninner HI mass becomes much weaker when the gas-phase metallicity is derived in\nthe central region instead of at the effective radius. These results support\nthe idea that the scatter in the mass-metallicity relation is regulated by gas\naccretion, and not directly by the SFR, and stress the importance of deriving\nthe gas mass and the metallicity from roughly the same region. The new relation\nbetween inner HI mass and gas-phase metallicity will provide new constraints\nfor chemical and galaxy evolution models." }, { "anchor": "ALMA captures feeding and feedback from the active galactic nucleus in\n NGC613: We report ALMA observations of CO(3-2) emission in the Seyfert galaxy NGC613,\nat a spatial resolution of 17pc, as part of our NUclei of GAlaxies sample. Our\naim is to investigate the morphology and dynamics of the gas inside the central\nkpc, and to probe nuclear fueling and feedback phenomena. The morphology of\nCO(3-2) line emission reveals a 2-arm trailing nuclear spiral at\n$r\\lesssim$100pc and a circumnuclear ring at ~350pc radius, that is coincident\nwith the star-forming ring seen in the optical images. The molecular gas in the\ngalaxy disk is in a remarkably regular rotation, however, the kinematics in the\nnuclear region is very skewed. The nuclear spectrum of CO and dense gas tracers\nHCN(4-3), HCO+(4-3), and CS(7-6) show broad wings up to $\\pm$300km/s,\nassociated with a molecular outflow emanating from the nucleus (r~25pc). We\nderive a molecular outflow mass $M_{out}$=2x10$^6$M$_\\odot$ and a mass outflow\nrate of $\\dot{M}_{out}=$27$\\rm M_\\odot yr^{-1}$. The molecular outflow\nenergetics exceed the values predicted by AGN feedback models: the kinetic\npower of the outflow corresponds to 20%L_AGN and the momentum rate is\n$\\dot{M}_{out}v\\sim400L_{AGN}/c$. The outflow is mainly boosted by the AGN\nthrough entrainment by the radio jet, but given the weak nuclear activity of\nNGC613, we might be witnessing a fossil outflow, resulted from a strong past\nAGN that now has already faded. The nuclear trailing spiral observed in CO\nemission is inside the ILR ring of the bar. We compute the gravitational\ntorques exerted in the gas to estimate the efficiency of the angular momentum\nexchange. The gravity torques are negative from 25 to 100pc and the gas loses\nits angular momentum in a rotation period, providing evidence of a highly\nefficient inflow towards the center. This phenomenon shows that the massive\ncentral black hole has a significant dynamical influence on the gas, triggering\nits fueling.", "positive": "Herschel Gould Belt Survey Observations of Dense Cores in the Cepheus\n Flare Clouds: We present Herschel SPIRE and PACS maps of the Cepheus Flare clouds L1157,\nL1172, L1228, L1241, and L1251, observed by the Herschel Gould Belt Survey\n(HGBS) of nearby star-forming molecular clouds. Through modified blackbody fits\nto the SPIRE and PACS data, we determine typical cloud column densities of\n0.5-1.0 $\\times$ 10$^{21}$ cm$^{-2}$ and typical cloud temperatures of 14-15 K.\nUsing the getsources identification algorithm, we extract 832 dense cores from\nthe SPIRE and PACS data at 160-500 $\\mu$m. From placement in a mass vs. size\ndiagram, we consider 303 to be candidate prestellar cores, and 178 of these to\nbe \"robust\" prestellar cores. From an independent extraction of sources at 70\n$\\mu$m, we consider 25 of the 832 dense cores to be protostellar. The\ndistribution of background column densities coincident with candidate\nprestellar cores peaks at 2-4 $\\times$ 10$^{21}$ cm$^{-2}$. About half of the\ncandidate prestellar cores in Cepheus may have formed due to the widespread\nfragmentation expected to occur within filaments of \"transcritical\" line mass.\nThe lognormal robust prestellar core mass function (CMF) drawn from all five\nCepheus clouds peaks at 0.56 M$_{\\odot}$ and has a width of $\\sim$0.5 dex,\nsimilar to that of Aquila's CMF. Indeed, the width of Cepheus' aggregate CMF is\nsimilar to the stellar system Initial Mass Function (IMF). The similarity of\nCMF widths in different clouds and the system IMF suggests a common, possibly\nturbulent origin for seeding the fluctuations that evolve into prestellar cores\nand stars." }, { "anchor": "High-velocity gas towards the LMC resides in the Milky Way halo: To explore the origin of high-velocity gas in the direction of the Large\nMagellanic Cloud (LMC) we analyze absorption lines in the ultraviolet spectrum\nof a Galactic halo star that is located in front of the LMC at d=9.2 kpc\ndistance. We study the velocity-component structure of low and intermediate\nmetal ions in the spectrum of RXJ0439.8-6809, as obtained with the Cosmic\nOrigins Spectrograph (COS) onboard HST, and measure equivalent widths and\ncolumn densities for these ions. We supplement our COS data with a\nFar-Ultraviolet Spectroscopic Explorer spectrum of the nearby LMC star Sk-69 59\nand with HI 21cm data from the Leiden-Argentina-Bonn (LAB) survey. Metal\nabsorption towards RXJ0439.8-6809 is unambiguously detected in three different\nvelocity components near v_LSR=0,+60, and +150 km/s. The presence of absorption\nproves that all three gas components are situated in front of the star, thus\nbeing located in the disk and inner halo of the Milky Way. For the\nhigh-velocity cloud (HVC) at v_LSR=+150 km/s we derive an oxygen abundance of\n[O/H]=-0.63 (~0.2 solar) from the neighbouring Sk-69 59 sightline, in\naccordance with previous abundance measurements for this HVC. From the observed\nkinematics we infer that the HVC hardly participates in the Galactic rotation.\nOur study shows that the HVC towards the LMC represents a Milky Way halo cloud\nthat traces low-column density gas with relatively low metallicity. It rules\nout scenarios in which the HVC represents material close to the LMC that stems\nfrom a LMC outflow.", "positive": "Code Comparison in Galaxy Scale Simulations with Resolved Supernova\n Feedback: Lagrangian vs. Eulerian Methods: We present a suite of high-resolution simulations of an isolated dwarf galaxy\nusing four different hydrodynamical codes: {\\sc Gizmo}, {\\sc Arepo}, {\\sc\nGadget}, and {\\sc Ramses}. All codes adopt the same physical model which\nincludes radiative cooling, photoelectric heating, star formation, and\nsupernova (SN) feedback. Individual SN explosions are directly resolved without\nresorting to sub-grid models, eliminating one of the major uncertainties in\ncosmological simulations. We find reasonable agreement on the time-averaged\nstar formation rates as well as the joint density-temperature distributions\nbetween all codes. However, the Lagrangian codes show significantly burstier\nstar formation, larger supernova-driven bubbles, and stronger galactic outflows\ncompared to the Eulerian code. This is caused by the behavior in the dense,\ncollapsing gas clouds when the Jeans length becomes unresolved: gas in\nLagrangian codes collapses to much higher densities than in Eulerian codes, as\nthe latter is stabilized by the minimal cell size. Therefore, more of the gas\ncloud is converted to stars and SNe are much more clustered in the Lagrangian\nmodels, amplifying their dynamical impact. The differences between Lagrangian\nand Eulerian codes can be reduced by adopting a higher star formation\nefficiency in Eulerian codes, which significantly enhances SN clustering in the\nlatter. Adopting a zero SN delay time reduces burstiness in all codes,\nresulting in vanishing outflows as SN clustering is suppressed." }, { "anchor": "Revealing ringed galaxies in group environments: Aims. We explore galaxies with ringed structures inhabiting poor and rich\ngroups with the aim of assessing the effects of local density environments on\nringed galaxy properties. Methods. We identified galaxies with inner, outer,\nnuclear, inner+outer (inner and outer rings combined), and partial rings that\nreside in groups by cross-correlating a sample of ringed galaxies with a group\ncatalog obtained from Sloan Digital Sky Survey (SDSS). The resulting sample was\ndivided based on group richness. To quantify the effects of rings and the role\nof local density environment on galaxy properties, we constructed a suitable\ncontrol sample for each catalog of ringed galaxies, consisting of non-ringed\ngalaxies with similar values for the z, magnitude, morphology, group masses,\nand environmental density distributions as those of ringed ones. We explored\nthe occurrence of ringed galaxies in poor and rich groups and analyzed several\ngalaxy properties, such as SFR, stellar populations, and colors. Results. We\nobtained a sample of 637 ringed galaxies residing in groups. With 76% of these\ngalaxies inhabiting poor groups and 24% rich groups. In addition, ringed\ngalaxies in groups display a reduction in their star formation activity and\naged stellar populations, compared to non-ringed ones in the control samples.\nHowever, the SFR is higher for nuclear rings in poor groups than for other\ntypes. This disparity may stem from the environmental influence on the internal\nprocesses of galaxies, either enhancing or diminishing star formation. Ringed\ngalaxies also show an excess of red colors and tend to populate the green\nvalley and the red sequence of color-magnitude and color-color diagrams, with a\nsurplus of galaxies in the red sequence, while non-ringed galaxies are found in\nthe green valley and the blue region. These trends are more significant in\ngalaxies with ringed structures residing in rich groups.", "positive": "Exemplary Merging Clusters: Weak-lensing and X-ray Analysis of the\n Double Radio Relic Merging Galaxy Clusters MACS 1752.0+4440 and ZWCL\n 1856.8+6616: The investigation of merging galaxy clusters that exhibit radio relics is\nstrengthening our understanding of the formation and evolution of galaxy\nclusters, the nature of dark matter, the intracluster medium, and astrophysical\nparticle acceleration. Each merging cluster provides only a single view of the\ncluster formation process and the variety of merging clusters is vast. Clusters\nhosting double radio relics are rare and extremely important because they allow\ntight constraints on the merger scenario. We present a weak-lensing and X-ray\nanalysis of MACSJ1752.0+4440 ($z$=0.365) and ZWCL1856.8+6616 ($z$=0.304), two\ndouble radio relic clusters. Our weak-lensing mass estimates show that each\ncluster is a major merger with approximately 1:1 mass ratio. The total mass of\nMACSJ1752.0+4440 (ZWCL1856.8+6616) is $M_{200}=14.7^{+3.8}_{-3.3}\\times10^{14}\\\n$M$_\\odot$ ($M_{200}=2.4^{+0.9}_{-0.7}\\times10^{14}\\ $M$_\\odot$). We find that\nthese two clusters have comparable features in their weak-lensing and gas\ndistributions, even though the systems have vastly different total masses. From\nthe likeness of the X-ray morphologies and the remarkable symmetry of the radio\nrelics, we propose that both systems underwent nearly head-on collisions.\nHowever, revelations from the hot-gas features and our multiwavelength data\nanalysis suggest that ZWCL1856.8+6618 is likely at a later merger phase than\nMACSJ1752.0+4440. We postulate that the SW radio relic in MACSJ1752.0+4440 is a\nresult of particle re-acceleration." }, { "anchor": "Hierarchical Star Formation across the ring galaxy NGC 6503: We present a detailed clustering analysis of the young stellar population\nacross the star-forming ring galaxy NGC 6503, based on the deep HST photometry\nobtained with the Legacy ExtraGalactic UV Survey (LEGUS). We apply a\ncontour-based map analysis technique and identify in the stellar surface\ndensity map 244 distinct star-forming structures at various levels of\nsignificance. These stellar complexes are found to be organized in a\nhierarchical fashion with 95% being members of three dominant super-structures\nlocated along the star-forming ring. The size distribution of the identified\nstructures and the correlation between their radii and numbers of stellar\nmembers show power-law behaviors, as expected from scale-free processes. The\nself-similar distribution of young stars is further quantified from their\nautocorrelation function, with a fractal dimension of ~1.7 for length-scales\nbetween ~20 pc and 2.5 kpc. The young stellar radial distribution sets the\nextent of the star-forming ring at radial distances between 1 and 2.5 kpc.\nAbout 60% of the young stars belong to the detected stellar structures, while\nthe remaining stars are distributed among the complexes, still inside the ring\nof the galaxy. The analysis of the time-dependent clustering of young\npopulations shows a significant change from a more clustered to a more\ndistributed behavior in a time-scale of ~60 Myr. The observed hierarchy in\nstellar clustering is consistent with star formation being regulated by\nturbulence across the ring. The rotational velocity difference between the\nedges of the ring suggests shear as the driving mechanism for this process. Our\nfindings reveal the interesting case of an inner ring forming stars in a\nhierarchical fashion.", "positive": "Cracking the relation between mass and 1P-star fraction of globular\n clusters: I. Present-day cluster masses as a first tool: The phenomenon of multiple stellar populations is exacerbated in massive\nglobular clusters, with the fraction of first-population (1P) stars a\ndecreasing function of the cluster present-day mass. We decipher this relation\nin far greater detail than has been done so far. We assume (i) a fixed stellar\nmass threshold for the formation of second-population (2P) stars, (ii) a\npower-law scaling $F_{1P} \\propto m_{ecl}^{-1}$ between the mass $m_{ecl}$ of\nnewly-formed clusters and their 1P-star fraction $F_{1P}$, and (iii) a constant\n$F_{1P}$ over time. The $F_{1P}(m_{ecl})$ relation is then evolved up to an age\nof 12Gyr for tidal field strengths representative of the entire Galactic halo.\nThe 12Gyr-old model tracks cover extremely well the present-day distribution of\nGalactic globular clusters in (mass,$F_{1P}$) space. The distribution is\ncurtailed on its top-right side by the scarcity of clusters at large\nGalactocentric distances, and on its bottom-left side by the initial scarcity\nof very high-mass clusters, and dynamical friction. Given their distinct\ndissolution rates, \"inner\" and \"outer\" model clusters are offset from each\nother, as observed. The locus of Magellanic Clouds clusters in (mass,$F_{1P}$)\nspace is as expected for intermediate-age clusters evolving in a gentle tidal\nfield. Given the assumed constancy of $F_{1P}$, we conclude that 2P-stars do\nnot necessarily form centrally-concentrated. We infer a minimum mass of $4\n\\cdot 10^5~M_{\\odot}$ for multiple-populations clusters at secular evolution\nonset. This high-mass threshold severely limits the amount of 2P-stars lost\nfrom evolving clusters, thereby fitting the low 2P-star fraction of the\nGalactic halo field." }, { "anchor": "What is limiting near-infrared astrometry in the Galactic Center?: We systematically investigate the error sources for high-precision astrometry\nfrom adaptive optics based near-infrared imaging data. We focus on the\napplication in the crowded stellar field in the Galactic Center. We show that\nat the level of <=100 micro-arcseconds a number of effects are limiting the\naccuracy. Most important are the imperfectly subtracted seeing halos of\nneighboring stars, residual image distortions and unrecognized confusion of the\ntarget source with fainter sources in the background. Further contributors to\nthe error budget are the uncertainty in estimating the point spread function,\nthe signal-to-noise ratio induced statistical uncertainty, coordinate\ntransformation errors, the chromaticity of refraction in Earth's atmosphere,\nthe post adaptive optics differential tilt jitter and anisoplanatism. For stars\nas bright as mK=14, residual image distortions limit the astrometry, for\nfainter stars the limitation is set by the seeing halos of the surrounding\nstars. In order to improve the astrometry substantially at the current\ngeneration of telescopes, an adaptive optics system with high performance and\nweak seeing halos over a relatively small field (r<=3\") is suited best.\nFurthermore, techniques to estimate or reconstruct the seeing halo could be\npromising.", "positive": "Re-interpretation of \"Bar slowdown and the distribution of dark matter\n in barred galaxies\" by Athanassoula: Athanassoula (2014) has claimed that measurements of the ratio of corotation\nradius to bar length in galaxies do not place a constraint on the disk to halo\nmass ratio. Her conclusion was based on a series of simulations published by\nAthanassoula et al. (2013). Here we show that these results are, in fact,\nconsistent with previous work on the slow down of bars due to dynamical\nfriction because gas inflow rearranges the disk mass before the bar settles. It\ntherefore remains true that a bar rotating sufficiently fast that corotation is\nnot far beyond the bar end requires a near maximum disk." }, { "anchor": "A global view on star formation: The GLOSTAR Galactic plane survey. VII.\n Supernova remnants in the Galactic longitude range $28^\\circ -1), the trend is reversed, with < 30% of\nAGN having log NH > 22, which we suggest is mainly due to the small fraction of\ntime spent in a highly obscured state. Considering the Eddington ratio\ndistribution function of narrow-line and broad-line AGN from our prior work, we\nsee a qualitatively similar picture. To disentangle temporal and geometric\neffects at high lamEdd, we explore plausible clearing scenarios such that the\ntime-weighted covering factors agree with the observed population ratio. We\nfind that the low fraction of obscured AGN at high lamEdd is primarily due to\nthe fact that the covering factor drops very rapidly, with more than half the\ntime is spent with < 10% covering factor. We also find that nearly all obscured\nAGN at high-lamEdd exhibit some broad-lines. We suggest that this is because\nthe height of the depleted torus falls below the height of the broad-line\nregion, making the latter visible from all lines of sight.", "positive": "The NH$_2$D hyperfine structure revealed by astrophysical observations: The 1$_{11}$-1$_{01}$ lines of ortho and para--NH$_2$D (o/p-NH$_2$D),\nrespectively at 86 and 110 GHz, are commonly observed to provide constraints on\nthe deuterium fractionation in the interstellar medium. In cold regions, the\nhyperfine structure due to the nitrogen ($^{14}$N) nucleus is resolved. To\ndate, this splitting is the only one which is taken into account in the NH$_2$D\ncolumn density estimates. We investigate how the inclusion of the hyperfine\nsplitting caused by the deuterium (D) nucleus affects the analysis of the\nrotational lines of NH$_2$D. We present 30m IRAM observations of the above\nmentioned lines, as well as APEX o/p-NH$_2$D observations of the\n1$_{01}$-0$_{00}$ lines at 333 GHz. The hyperfine spectra are first analyzed\nwith a line list that only includes the hyperfine splitting due to the $^{14}$N\nnucleus. We find inconsistencies between the line widths of the\n1$_{01}$-0$_{00}$ and 1$_{11}$-1$_{01}$ lines, the latter being larger by a\nfactor of $\\sim$1.6$\\pm0.3$. Such a large difference is unexpected given the\ntwo sets of lines are likely to originate from the same region. We next employ\na newly computed line list for the o/p-NH$_2$D transitions, where the hyperfine\nstructure induced by both nitrogen and deuterium nuclei is included. With this\nnew line list, the analysis of the previous spectra leads to linewidths which\nare compatible. Neglecting the hyperfine structure owing to D leads to\noverestimate the linewidths of the o/p-NH$_2$D lines at 3 mm. The error for a\ncold molecular core is about 50\\%. This error propagates directly to the column\ndensity estimate. It is therefore recommended to take into account the\nhyperfine splittings caused by both the $^{14}$N and D nuclei in any analysis\nrelying on these lines." }, { "anchor": "The star formation history in the last 10 billion years from CIB\n cross-correlations: The Cosmic Infrared Background (CIB) traces the emission of star-forming\ngalaxies throughout all cosmic epochs. Breaking down the contribution from\ngalaxies at different redshifts to the observed CIB maps would allow us to\nprobe the history of star formation. In this paper, we cross-correlate maps of\nthe CIB with galaxy samples covering the range $z\\lesssim2$ to measure the\nbias-weighted star-formation rate (SFR) density $\\langle b\\rho_{\\rm\nSFR}\\rangle$ as a function of time in a model independent way. This quantity is\ncomplementary to direct measurements of the SFR density $\\rho_{\\rm SFR}$,\ngiving a higher weight to more massive haloes, and thus provides additional\ninformation to constrain the physical properties of star formation. Using\ncross-correlations of the CIB with galaxies from the DESI Legacy Survey and the\nextended Baryon Oscillation Spectroscopic Survey, we obtain high\nsignal-to-noise ratio measurements of $\\langle b\\rho_{\\rm SFR}\\rangle$, which\nwe then use to place constraints on halo-based models of the star-formation\nhistory. We fit halo-based SFR models to our data and compare the recovered\n$\\rho_{\\rm SFR}$ with direct measurements of this quantity. We find a\nqualitatively good agreement between both independent datasets, although the\ndetails depend on the specific halo model assumed. This constitutes a useful\nrobustness test for the physical interpretation of the CIB, and reinforces the\nrole of CIB maps as valuable astrophysical probes of the large-scale structure.\nWe report our measurements of $\\langle b\\rho_{\\rm SFR}\\rangle$ as well as a\nthorough account of their statistical uncertainties, which can be used to\nconstrain star formation models in combination with other data.", "positive": "The Cosmic Evolution of Magnesium Isotopes: The abundance of magnesium in the interstellar medium is a powerful probe of\nstar formation processes over cosmological timescales. Magnesium has three\nstable isotopes, 24Mg, 25Mg, 26Mg, which can be produced both in massive and\nintermediate-mass (IM) stars with masses between 2 and 8 M_\\odot. In this work,\nwe use constraints on the cosmic star formation rate density (SFRD) and explore\nthe role and mass range of intermediate mass stars using the observed isotopic\nratios. We compare several models of stellar nucleosynthesis with\nmetallicity-dependent yields and also consider the effect of rotation on the\nyields massive stars and its consequences on the evolution of the Mg isotopes.\nWe use a cosmic evolution model updated with new observational SFRD data and\nnew reionization constraints coming from 2018 Planck collaboration\ndeterminations. We find that the main contribution of 24Mg comes from massive\nstars whereas 25Mg and 26Mg come from intermediate mass stars. To fit the\nobservational data on magnesium isotopic ratios, an additional intermediate\nmass SFRD component is preferred. Moreover, the agreement between model and\ndata is further improved when the range of IM masses is narrowed towards higher\nmasses (5-8 M_\\odot). While some rotation also improves the fit to data, we can\nexclude the case where all stars have high rotational velocities due to an\nover-production of 26Mg." }, { "anchor": "The discovery of blue-cored dwarf early-type galaxies in isolated\n environments: The presence of blue-cored dwarf early-type galaxies (dE(bc)s) in\nhigh-density environments supports the scenario of the transformation of\ninfalling late-type galaxies into quiescent dwarf early-type galaxies by\nenvironmental effects. While low-density environments lacking environmental\nprocesses could not be relevant to the formation of dE(bc)s, we discovered a\nlarge sample of rare dE(bc)s in isolated environments at z < 0.01 using the\nNASA-Sloan Atlas catalog. Thirty-two isolated dE(bc)s were identified by visual\ninspection of the Sloan Digital Sky Survey images and g - r color profiles. We\nfound that (1) isolated dE(bc)s exhibit similar structural parameters to\ndE(bc)s in the Virgo cluster; (2) based on the ultraviolet-r color-magnitude\nrelation, color gradients, and optical emission lines of dE(bc)s, isolated\ndE(bc)s show more vigorous, centrally concentrated SF compared to their\ncounterparts in the Virgo cluster; (3) at a given stellar mass, isolated\ndE(bc)s tend to have a larger fraction of gas mass than their Virgo\ncounterparts. We discuss a scenario of episodic SF sustained by gas accretion,\nsuggested by Sanchez Almeida et al., in which the star-bursting blue compact\ndwarf galaxy (BCD)-quiescent BCD (QBCD) cycle can be repeated during the Hubble\ntime. We suggest that, in this cadence, isolated dE(bc)s might be QBCDs at pre-\nor post-BCD stages. Our results imply that dE(bc)s comprise a mixture of\nobjects with two types of origins, nature or nurture, depending on their\nenvironment.", "positive": "Magnetohydrodynamics using path or stream functions: Magnetization in highly conductive plasmas is ubiquitous to astronomical\nsystems. Flows in such media can be described by three path functions\n$\\Lambda_\\alpha$, or, for a steady flow, by two stream functions\n$\\lambda_\\kappa$ and an additional field such as the mass density $\\rho$,\nvelocity $v$, or travel time $\\Delta t$. While typical analyses of a frozen\nmagnetic field $\\boldsymbol{B}$ are problem-specific and involve nonlocal\ngradients of the fluid element position $\\boldsymbol{x}(t)$, we derive the\ngeneral, local (in $\\Lambda$ or $\\lambda$ space) solution\n$\\boldsymbol{B}=(\\partial\\boldsymbol{x}/\\partial\\Lambda_\\alpha)_t\n\\tilde{B}_\\alpha \\rho/\\tilde{\\rho}$, where Lagrangian constants denoted by a\ntilde are directly fixed at a boundary hypersurface $\\tilde{H}$ on which\n$\\boldsymbol{B}$ is known. For a steady flow,\n$\\tilde{\\rho}\\boldsymbol{B}/\\rho=(\\partial\\boldsymbol{x}/\\partial\\lambda_\\kappa)_{\\Delta\nt}\\tilde{B}_\\kappa+\\boldsymbol{v}\\tilde{B}_3/\\tilde{v}$; here the electric\nfield\n$\\boldsymbol{E}\\sim(\\tilde{B}_2\\boldsymbol{\\nabla}\\lambda_1-\\tilde{B}_1\\boldsymbol{\\nabla}\\lambda_2)/\\tilde{\\rho}$\ndepends only on $\\lambda_\\kappa$ and the boundary conditions. Illustrative\nspecial cases include compressible axisymmetric flows and incompressible flows\naround a sphere, showing that viscosity and compressibility enhance the\nmagnetization and lead to thicker boundary layers. Our method is especially\nuseful for directly computing electric fields, and for addressing upstream\nmagnetic fields that vary in spacetime. We thus estimate the electric fields\nabove heliospheres and magnetospheres, compute the draping of magnetic\nsubstructure around a planetary body, and demonstrate the resulting inverse\npolarity reversal layer. Our analysis can be incorporated into existing\nhydrodynamic codes that are based on stream or path functions. (Abridged)" }, { "anchor": "Gas Accretion via Lyman Limit Systems: In cosmological simulations, a large fraction of the partial Lyman limit\nsystems (pLLSs; 162) redshifts. Here I discuss unambiguous evidence for\nmetal-poor gas at all z probed by the pLLSs and LLSs. At z<1, all the pLLSs and\nLLSs so far studied are located in the CGM of galaxies with projected distances\n<100-200 kpc. Regardless of the exact origin of the low-metallicity pLLSs/LLSs,\nthere is a significant mass of cool, dense, low-metallicity gas in the CGM that\nmay be available as fuel for continuing star formation in galaxies over cosmic\ntime. As such, the metal-poor pLLSs and LLSs are currently among the best\nobservational evidence of cold, metal-poor gas accretion onto galaxies.", "positive": "A large sample of calibration stars for Gaia: log g from Kepler and\n CoRoT: Asteroseismic data can be used to determine surface gravities with precisions\nof < 0.05 dex by using the global seismic quantities Deltanu and nu_max along\nwith Teff and [Fe/H]. Surface gravity is also one of the four stellar\nproperties to be derived by automatic analyses for 1 billion stars from Gaia\ndata (workpackage GSP_Phot). We explore seismic data from MS F, G, K stars\n(solar-like stars) observed by Kepler as a potential calibration source for\nmethods that Gaia will use for object characterisation (log g). We calculate\nlog g for bright nearby stars for which radii and masses are known, and using\ntheir global seismic quantities in a grid-based method, we determine an\nasteroseismic log g to within 0.01 dex of the direct calculation, thus\nvalidating the accuracy of our method. We find that errors in Teff and mainly\n[Fe/H] can cause systematic errors of 0.02 dex. We then apply our method to a\nlist of 40 stars to deliver precise values of surface gravity, i.e. sigma <\n0.02 dex, and we find agreement with recent literature values. Finally, we\nexplore the precision we expect in a sample of 400+ Kepler stars which have\ntheir global seismic quantities measured. We find a mean uncertainty\n(precision) on the order of <0.02 dex in log g over the full explored range 3.8\n< log g < 4.6, with the mean value varying only with stellar magnitude (0.01 -\n0.02 dex). We study sources of systematic errors in log g and find possible\nbiases on the order of 0.04 dex, independent of log g and magnitude, which\naccounts for errors in the Teff and [Fe/H] measurements, as well as from using\na different grid-based method. We conclude that Kepler stars provide a wealth\nof reliable information that can help to calibrate methods that Gaia will use,\nin particular, for source characterisation with GSP_Phot where excellent\nprecision (small uncertainties) and accuracy in log g is obtained from seismic\ndata." }, { "anchor": "The origin and properties of massive prolate galaxies in the Illustris\n simulation: We study galaxy shapes in the Illustris cosmological hydrodynamic simulation.\nWe find that massive galaxies have a higher probability of being prolate. For\ngalaxies with stellar mass larger than $10^{11}\\rm M_{\\odot}$, 35 out of total\n839 galaxies are prolate. For 21 galaxies with stellar mass larger than\n$10^{12}\\rm M_{\\odot}$, 9 are prolate, 4 are triaxial while the others are\nclose to being oblate. There are almost no prolate galaxies with stellar mass\nsmaller than $3\\times10^{11}\\rm M_{\\odot}$. We check the merger history of the\nprolate galaxies, and find that they are formed by major dry mergers. All the\nprolate galaxies have at least one such merger, with most having mass ratios\nbetween $1:1$ and $1:3$. The gas fraction (gas mass to total baryon mass) of\nthe progenitors is 0-3 percent for nearly all these mergers, except for one\nwhose second progenitor contains $\\sim 15\\%$ gas mass, while its main\nprogenitor still contains less than $5\\%$. For the 35 massive prolate galaxies\nthat we find, 18 of them have minor axis rotation, and their angular momenta\nmostly come from the spin angular momenta of the progenitors (usually that of\nthe main progenitor). We analyse the merger orbits of these prolate galaxies\nand find that most of them experienced a nearly radial merger orbit. Oblate\ngalaxies with major dry mergers can have either radial or circular merger\norbits. We further discuss various properties of these prolate galaxies, such\nas spin parameter $\\lambda_{\\rm R}$, spherical anisotropy parameter $\\beta$,\ndark matter fraction, as well as inner density slopes for the stellar, dark\nmatter and total mass distributions.", "positive": "Galaxy cluster cores as seen with VLT/MUSE: new strong-lensing analyses\n of RX J2129.4+0009, MS 0451.6-0305 & MACSJ2129.4-0741: We present strong-lensing analyses of three galaxy clusters, RXJ2129.4+0009\n(z=0.235), MS0451.6-0305 (z=0.55), and MACSJ2129.4-0741 (z=0.589), using the\npowerful combination of Hubble Space Telescope (HST) multi-band observations,\nand Multi-Unit Spectroscopic Explorer (MUSE) spectroscopy. In RXJ2129, we newly\nspectroscopically confirm 15 cluster members. Our resulting mass model uses 8\nmultiple image systems as we include a galaxy-galaxy lensing system North-East\nof the cluster, and is composed of 71 halos including one dark matter\ncluster-scale halo and 2 galaxy-scale halos optimized individually. For MS0451,\nwe report the spectroscopic identification of 2 new systems of multiple images\nin the Northern region, and 112 cluster members. Our mass model uses 16\nmultiple image systems, and 146 halos, including 2 large-scale halos, and 7\ngalaxy-scale halos independently optimized. For MACSJ2129, we report the\nspectroscopic identification of one new multiple image system at z=4.41, and\nnewly measure spectroscopic redshifts for 4 cluster members. Our mass model\nuses 14 multiple image systems, and is composed of 151 halos, including 2\nlarge-scale halos and 4 galaxy-scale halos independently optimized. Our best\nmodels have rms of 0.29'', 0.6'', 0.74'' in the image plane for RXJ2129,\nMS0451, and MACSJ2129 respectively. This analysis presents a detailed\ncomparison with the existing literature showing excellent agreements, and\ndiscuss specific studies of lensed galaxies, e.g. a group of submilimeter\ngalaxies at z=2.9 in MS0451, and a bright z=2.1472 red singly imaged galaxy in\nMACSJ2129." }, { "anchor": "Cosmic Rays in the Milky Way and Beyond: Cosmic rays (CRs) are the probes of the deep space. They allow us to study\nparticle acceleration, chemical composition of the interstellar medium, and\nglobal properties of our Galaxy. However, until recently studies of CRs were\nsimilar to astronomical observations with blurred lenses that capture only the\nintegral brightness of all stars in the field of view. Thanks to the recent\ntechnological developments, our \"lenses\" are now capable of capturing sharp\nimages and making precise measurements of all CR species. We have a full range\nof unique instrumentation for direct measurements of CRs in space and for\nmulti-wavelength observations of their emissions and more missions are coming.\nThe unveiling picture is astonishing. This paper gives a short overview of very\nexciting developments in astrophysics of CRs in the Milky Way and in other\nstar-forming galaxies.", "positive": "Comparative Electron Irradiations of Amorphous and Crystalline\n Astrophysical Ice Analogues: Laboratory studies of the radiation chemistry occurring in astrophysical ices\nhave demonstrated the dependence of this chemistry on a number of experimental\nparameters. One experimental parameter which has received significantly less\nattention is that of the phase of the solid ice under investigation. In this\npresent study, we have performed systematic 2 keV electron irradiations of the\namorphous and crystalline phases of pure CH3OH and N2O astrophysical ice\nanalogues. Radiation-induced decay of these ices and the concomitant formation\nof products were monitored in situ using FT-IR spectroscopy. A direct\ncomparison between the irradiated amorphous and crystalline CH3OH ices revealed\na more rapid decay of the former compared to the latter. Interestingly, a\nsignificantly lesser difference was observed when comparing the decay rates of\nthe amorphous and crystalline N2O ices. These observations have been\nrationalised in terms of the strength and extent of the intermolecular forces\npresent in each ice. The strong and extensive hydrogen-bonding network that\nexists in crystalline CH3OH (but not in the amorphous phase) is suggested to\nsignificantly stabilise this phase against radiation-induced decay. Conversely,\nalthough alignment of the dipole moment of N2O is anticipated to be more\nextensive in the crystalline structure, its weak attractive potential does not\nsignificantly stabilise the crystalline phase against radiation-induced decay,\nhence explaining the smaller difference in decay rates between the amorphous\nand crystalline phases of N2O compared to those of CH3OH. Our results are\nrelevant to the astrochemistry of interstellar ices and icy Solar System\nobjects, which may experience phase changes due to thermally-induced\ncrystallisation or space radiation-induced amorphisation." }, { "anchor": "Detecting Changing Polarization Structures in Sagittarius A* with High\n Frequency VLBI: Sagittarius A* is the source of near infrared, X-ray, radio, and\n(sub)millimeter emission associated with the supermassive black hole at the\nGalactic Center. In the submillimeter regime, Sgr A* exhibits time-variable\nlinear polarization on timescales corresponding to <10 Schwarzschild radii of\nthe presumed 4 million solar mass black hole. In previous work, we demonstrated\nthe potential for total-intensity (sub)millimeter-wavelength VLBI to detect\ntime-variable -- and periodic -- source structure changes in the Sgr A* black\nhole system using nonimaging analyses. Here we extend this work to include full\npolarimetric VLBI observations. We simulate full-polarization (sub)millimeter\nVLBI data of Sgr A* using a hot-spot model that is embedded within an accretion\ndisk, with emphasis on nonimaging polarimetric data products that are robust\nagainst calibration errors. Although the source-integrated linear polarization\nfraction in the models is typically only a few percent, the linear polarization\nfraction on small angular scales can be much higher, enabling the detection of\nchanges in the polarimetric structure of Sgr A* on a wide variety of baselines.\nThe shortest baselines track the source-integrated linear polarization\nfraction, while longer baselines are sensitive to polarization substructures\nthat are beam-diluted by connected-element interferometry. The detection of\nperiodic variability in source polarization should not be significantly\naffected even if instrumental polarization terms cannot be calibrated out. As\nmore antennas are included in the (sub)mm-VLBI array, observations with full\npolarization will provide important new diagnostics to help disentangle\nintrinsic source polarization from Faraday rotation effects in the accretion\nand outflow region close to the black hole event horizon.", "positive": "The hierarchical assembly of galaxies and black holes in the first\n billion years: predictions for the era of gravitational wave astronomy: In this work we include black hole (BH) seeding, growth and feedback into our\nsemi-analytic galaxy formation model, Delphi. Our model now fully tracks the,\naccretion- and merger-driven, hierarchical assembly of the dark matter halo,\nbaryonic and BH masses of high-redshift ($z>5$) galaxies. We use a minimal set\nof mass- and $z$-independent free parameters associated with star formation and\nBH growth (and feedback) and include suppressed BH growth in low-mass galaxies\nto explore a number of physical scenarios including: (i) two types of BH seeds\n(stellar and those from Direct Collapse BH; DCBH); (ii) the impact of\nreionization feedback; and (iii) the impact of instantaneous versus delayed\ngalaxy mergers on the baryonic growth. While both reionization feedback and\ndelayed galaxy mergers have no sensible impact on the evolving ultra-violet\nluminosity function, the latter limits the maximum BH masses achieved at these\nhigh-$z$. We then use this model, baselined against all available high-$z$\ngalaxy and BH data-sets, to predict the LISA detectability of merger events at\n$z > 5$. As expected, the merger rate is dominated by stellar BH mergers for\nall scenarios and our model predicts an expected upper limit of about 20\nmergers in the case of instantaneous merging and no reionization feedback over\nthe 4-year mission duration. Including the impact of delayed mergers and\nreionization feedback reduces this to about 12 events over the same\nobservational time-scale." }, { "anchor": "The Origin of Filamentary Star Forming Clouds in Magnetised Galaxies: Observations show that galaxies and their interstellar media are pervaded by\nstrong magnetic fields with energies in the diffuse component being at least\ncomparable to the thermal and even as large or larger than the turbulent\nenergy. Such strong magnetic fields prevent the formation of stars because\npatches of the interstellar medium are magnetically subcritical. Here we\npresent the results from global numerical simulations of strongly magnetised\nand self-gravitating galactic discs, which show that the buoyancy of the\nmagnetic field due to the Parker instability leads at first to the formation of\ngiant filamentary regions. These filamentary structures become gravitationally\nunstable and fragment into $\\sim10^5 M_{\\odot}$ clouds that attract kpc long,\ncoherent filamentary flows that build them into GMCs. Our results thus provide\na solution to the long-standing problem of how the transition from sub- to\nsupercritical regions in the interstellar medium proceeds.", "positive": "High velocity stars from the interaction of a globular cluster and a\n massive black hole binary: High velocity stars are stars moving at velocities so high to require an\nacceleration mechanism involving binary systems or the presence of a massive\ncentral black hole. In the frame of a galaxy hosting a supermassive black hole\nbinary (of total mass $10^8$ M$_\\odot$), we investigated a mechanism for the\nproduction of high velocity stars due to the close interaction between a\nmassive and orbitally decayed globular cluster and the super massive black hole\nbinary. Some stars of the cluster acquire high velocities by conversion of\ngravitational energy into kinetic energy deriving from their interaction with\nthe black hole binary. After the interaction, few stars reach a velocity\nsufficient to overcome the galactic gravitational well, while some of them are\njust stripped from the globular cluster and start orbiting around the galactic\ncentre." }, { "anchor": "On the Stability of Satellite Planes I: Effects of Mass, Velocity, Halo\n Shape and Alignment: The recently discovered vast thin plane of dwarf satellites orbiting the\nAndromeda Galaxy (M31) adds to the mystery of the small scale distribution of\nthe Local Group's galaxy population. Such well defined planar structures are\napparently rare occurrences in cold dark matter cosmological simulations, and\nwe lack a coherent explanation of their formation and existence. In this paper,\nwe explore the long-term survivability of thin planes of dwarfs in galactic\nhalos, focusing, in particular, on systems mimicking the observed Andromeda\ndistribution. The key results show that, in general, planes of dwarf galaxies\nare fragile, sensitive to the shape of the dark matter halo and other\nperturbing effects. In fact, long lived planes of satellites only exist in\npolar orbits in spherical dark matter halos, presenting a challenge to the\nobserved Andromeda plane which is significantly tilted with respect to the\noptical disk. Our conclusion is that, in standard cosmological models, planes\nof satellites are generally short lived, and hence we must be located at a\nrelatively special time in the evolution of the Andromeda Plane, lucky enough\nto see its coherent pattern.", "positive": "Mass loss rates and the mass evolution of star clusters: We describe the interplay between stellar evolution and dynamical mass loss\nof evolving star clusters, based on the principles of stellar evolution and\ncluster dynamics and on a grid of N-body simulations of cluster models. The\ncluster models have different initial masses, different orbits, including\nelliptical ones, and different initial density profiles. We use two sets of\ncluster models: initially Roche-lobe filling and Roche-lobe underfilling. We\nidentify four distinct mass loss effects: (1) mass loss by stellar evolution,\n(2) loss of stars induced by stellar evolution and (3) relaxation-driven mass\nloss before and (4) after core collapse. Both the evolution-induced loss of\nstars and the relaxation-driven mass loss need time to build up. This is\ndescribed by a delay-function of a few crossing times for Roche-lobe filling\nclusters and a few half mass relaxation times for Roche-lobe underfilling\nclusters. The relaxation-driven mass loss can be described by a simple power\nlaw dependence of the mass dM/dt =-M^{1-gamma}/t0, (with M in Msun) where t0\ndepends on the orbit and environment of the cluster. Gamma is 0.65 for clusters\nwith a King-parameter W0=5 and 0.80 for more concentrated clusters with W0=7.\nFor initially Roche-lobe underfilling clusters the dissolution is described by\nthe same gamma=0.80. The values of the constant t0 are described by simple\nformulae that depend on the orbit of the cluster. The mass loss rate increases\nby about a factor two at core collapse and the mass dependence of the\nrelaxation-driven mass loss changes to gamma=0.70 after core collapse. We also\npresent a simple recipe for predicting the mass evolution of individual star\nclusters with various metallicities and in different environments, with an\naccuracy of a few percent in most cases. This can be used to predict the mass\nevolution of cluster systems." }, { "anchor": "Using Machine Learning to Find Ghostly Damped Ly$\u03b1$ Systems in SDSS\n DR14: We report the discovery of 59 new ghostly absorbers from the Sloan Digital\nSky Survey (SDSS) Data Release 14 (DR14). These absorbers, with $z_{\\rm\nabs}$$\\sim$$z_{\\rm QSO}$, reveal no Ly$\\alpha$ absorption, and they are mainly\nidentified through the detection of strong metal absorption lines in the\nspectra. The number of previously known such systems is 30. The new systems are\nfound with the aid of machine learning algorithms. The spectra of 41 (out of\ntotal of 89) absorbers also cover the Ly$\\beta$ spectral region. By fitting the\ndamping wings of the Ly$\\beta$ absorption in the stacked spectrum of 21 (out of\n41) absorbers with relatively stronger Ly$\\beta$ absorption, we measured an HI\ncolumn density of log$N$(HI)=21.50. This column density is 0.5dex higher than\nthat of the previous work. We also found that the metal absorption lines in the\nstacked spectrum of the 21 ghostly absorbers with stronger Ly$\\beta$ absorption\nhave similar properties as those in the stacked spectrum of the remaining\nsystems. These circumstantial evidence strongly suggest that the majority of\nour ghostly absorbers are indeed DLAs.", "positive": "Two-photon production in low-velocity shocks: The Galactic interstellar medium abounds in low-velocity shocks with\nvelocities less than, say, about 70 km/s. Some are descendants of higher\nvelocity shocks, while others start off at low velocity (e.g., stellar bow\nshocks, intermediate velocity clouds, spiral density waves). Low-velocity\nshocks cool primarily via Ly-alpha, two-photon continuum, optical recombination\nlines (e.g., H-alpha), free-bound emission, free-free emission and forbidden\nlines of metals. The dark far-ultraviolet (FUV) sky, aided by the fact that the\ntwo-photon continuum peaks at 1400 angstroms, makes the FUV band an ideal\ntracer of low-velocity shocks. Recent GALEX FUV images reaffirm this\nexpectation, discovering faint and large interstellar structure in old\nsupernova remnants and thin arcs stretching across the sky. Interstellar bow\nshocks are expected from fast stars from the Galactic disk passing through the\nnumerous gas clouds in the local interstellar medium within 15 pc of the Sun.\nUsing the best atomic data available to date, we present convenient fitting\nformulae for yields of Ly$\\alpha$, two-photon continuum and H$\\alpha$ for pure\nhydrogen plasma in the temperature range of 10^4 K to 10^5 K. The formulae\npresented here can be readily incorporated into time-dependent cooling models\nas well as collisional ionization equilibrium models." }, { "anchor": "A comprehensive analysis using 9 dark matter halo models on the spiral\n galaxy NGC 4321: This paper addressed the dark matter analysis on the spiral galaxy NGC 4321\n(M100) by considering the nine different dark matter profiles so far lacking in\nthe scientific literature, i.e. Pseudoisothermal, Burkert, NFW, Moore, Einasto,\ncore-modified, DC14, coreNFW and Lucky13 profiles. In this paper, we analyzed\nthe rotation curve analysis on the galaxy NGC 4321 by using nonlinear fitting\nof star, gaseous and dark matter halo equations with selected VLA HI\nobservation data. Among the nine dark matter profiles, four dark matter\nprofiles (DC14, Lucky13, Burkert and Moore profiles) showed declining features\nand hence found to be not suitable for this galaxy. This is concluded to be\nmainly due to the characteristics of those dark matter profiles and also due to\nthe varying levels of problems within the inner regions fittings. For the\nremaining five accepted dark matter profiles, we further conducted analysis by\nusing the reduced chi-square test. Four out of the five accepted dark matter\nprofiles lie within the range of 0.40 < reduced chi-square < 1.70, except for\nthe case of the core-modified profile. In addition, Pseudoisothermal profile\nachieved the best fitting i.e. reduced chi-square nearest to 1, mainly due to\nits linearity in the inner region and flatness at large radii.", "positive": "The ISM scaling relations in DustPedia late-type galaxies: A benchmark\n study for the Local Universe: The purpose of this work is the characterization of the main scaling\nrelations between all the ISM components (dust, atomic/molecular/total gas),\ngas-phase metallicity, and other galaxy properties, such as Mstar and galaxy\nmorphology, for late-type galaxies in the Local Universe. This study is\nperformed by extracting late-type galaxies from the entire DustPedia sample and\nby exploiting the large and homogeneous dataset available thanks to the\nDustPedia project. The sample consists of 436 galaxies with morphological stage\nfrom T = 1 to 10, Mstar from 6 x 10^7 to 3 x 10^11 Msun, SFR from 6 x 10^(-4)\nto 60 Msun/yr, and 12 + log(O/H) from 8 to 9.5. The scaling relations involving\nthe molecular gas are studied by assuming both a constant and a\nmetallicity-dependent XCO. The analysis has been performed by means of the\nsurvival analysis technique. We confirm that the dust mass correlates very well\nwith the total gas mass, and find -- for the first time -- that the dust mass\ncorrelates better with the atomic gas mass than the molecular one. We\ncharacterize important mass ratios such as gas fraction, molecular-to-atomic\ngas mass ratio, dust-to-total gas mass ratio (DGR), and dust-to-stellar mass\nratio. Only the assumption of a metallicity-dependent XCO reproduces the\nexpected decrease of the DGR with increasing morphological stage and decreasing\ngas-phase metallicity, with a slope of about 1. DGR, gas-phase metallicity, and\nthe dust-to-stellar mass ratio are, for our galaxy sample, directly linked to\nthe galaxy morphology. The molecular-to-atomic gas mass ratio and the DGR show\na positive correlation for low molecular gas fractions, but for molecular gas\nrich galaxies this trend breaks down. This trend has never been found\npreviously, to our knowledge. It provides new constraints for theoretical\nmodels of galaxy evolution and a reference for high-redshift studies." }, { "anchor": "The ALMaQUEST Survey XII: Dense Molecular Gas as traced by HCN and\n HCO$^{+}$ in Green Valley Galaxies: We present ALMA observations of two dense gas tracers, HCN(1-0) and\nHCO$^{+}$(1-0), for three galaxies in the green valley and two galaxies on the\nstar-forming main sequence with comparable molecular gas fractions as traced by\nthe CO(1-0) emissions, selected from the ALMaQUEST survey. We investigate\nwhether the deficit of molecular gas star formation efficiency (SFE$_{\\rm\nmol}$) that leads to the low specific star formation rate in these green valley\ngalaxies is due to a lack of dense gas (characterized by the dense gas fraction\n$f_{\\rm dense}$) or the low star formation efficiency of dense gas (SFE$_{\\rm\ndense}$). We find that SFE$_{\\rm mol}$ as traced by the CO emissions, when\nconsidering both star-forming and retired spaxels together, is tightly\ncorrelated with SFE$_{\\rm dense}$ and depends only weakly on $f_{\\rm dense}$.\nThe specific star formation rate (sSFR) on kpc scales is primarily driven by\nSFE$_{\\rm mol}$ and SFE$_{\\rm dense}$, followed by the dependence on $f_{\\rm\nmol}$, and is least correlated with $f_{\\rm dense}$ or the dense-to-stellar\nmass ratio ($R_{\\rm dense}$). When compared with other works in the literature,\nwe find that our green valley sample shows lower global SFE$_{\\rm mol}$ as well\nas lower SFE$_{\\rm dense}$ while exhibiting similar dense gas fractions when\ncompared to star-forming and starburst galaxies. We conclude that the star\nformation of the 3 green valley galaxies with a normal abundance of molecular\ngas is suppressed mainly due to the reduced SFE$_{\\rm dense}$ rather than the\nlack of dense gas.", "positive": "Magnetic Field Structure of the Large Magellanic Cloud from Faraday\n Rotation Measures of Diffuse Polarized Emission: We present a study of the magnetic field of the Large Magellanic Cloud (LMC),\ncarried out using diffuse polarized synchrotron emission data at 1.4 GHz\nacquired at the Parkes Radio Telescope and the Australia Telescope Compact\nArray. The observed diffuse polarized emission is likely to originate above the\nLMC disk on the near side of the galaxy. Consistent negative rotation measures\n(RMs) derived from the diffuse emission indicate that the line-of-sight\nmagnetic field in the LMC's near-side halo is directed coherently away from us.\nIn combination with RMs of extragalactic sources that lie behind the galaxy, we\nshow that the LMC's large scale magnetic field is likely to be of quadrupolar\ngeometry, consistent with the prediction of dynamo theory. On smaller scales,\nwe identify two brightly polarized filaments southeast of the LMC, associated\nwith neutral hydrogen arms. The filaments' magnetic field potentially aligns\nwith the direction towards the Small Magellanic Cloud. We suggest that tidal\ninteractions between the Small and the Large Magellanic Clouds in the past 10^9\nyears is likely to have shaped the magnetic field in these filaments." }, { "anchor": "The central mass and mass-to-light profile of the Galactic globular\n cluster M15: We analyze line-of-sight velocity and proper motion data of stars in the\nGalactic globular cluster M15 using a new method to fit dynamical models to\ndiscrete kinematic data. Our fitting method maximizes the likelihood for\nindividual stars and, as such, does not suffer the same loss of spatial and\nvelocity information incurred when spatially binning data or measuring velocity\nmoments. In this paper, we show that the radial variation in M15 of the\nmass-to-light ratio is consistent with previous estimates and theoretical\npredictions, which verifies our method. Our best-fitting axisymmetric Jeans\nmodels do include a central dark mass of $\\sim2 \\pm 1\\cdot 10^3M_\\odot$, which\ncan be explained by a high concentration of stellar remnants at the cluster\ncenter. This paper shows that, from a technical point of view and with current\ncomputing power, spatial binning of data is no longer necessary. This not only\nleads to more accurate fits, but also avoids biased mass estimates due to the\nloss of resolution. Furthermore, we find that the mass concentration in M15 is\nsignificantly higher than previously measured, and is in close agreement with\ntheoretical predictions for core-collapsed globular clusters without a central\nintermediate-mass black hole.", "positive": "Exploring the z=3-4 massive galaxy population with ZFOURGE: the\n prevalence of dusty and quiescent galaxies: Our understanding of the redshift $z>3$ galaxy population relies largely on\nsamples selected using the popular \"dropout\" technique, typically consisting of\nUV-bright galaxies with blue colors and prominent Lyman breaks. As it is\ncurrently unknown if these galaxies are representative of the massive galaxy\npopulation, we here use the FourStar Galaxy Evolution (ZFOURGE) Survey to\ncreate a stellar mass-limited sample at $z=3-4$. Uniquely, ZFOURGE uses deep\nnear-infrared medium-bandwidth filters to derive accurate photometric redshifts\nand stellar population properties. The mass-complete sample consists of 57\ngalaxies with log M $>10.6$, reaching below $M^{\\star}$ at $z=3-4$.\n On average, the massive $z=3-4$ galaxies are extremely faint in the observed\noptical with median $R_{tot}^{AB}=27.48\\pm0.41$ (restframe\n$M_{1700}=-18.05\\pm0.37$). They lie far below the UV luminosity-stellar mass\nrelation for Lyman break galaxies and are about $\\sim100\\times$ fainter at the\nsame mass. The massive galaxies are red ($R-Ks_{AB}=3.9\\pm0.2$; restframe\nUV-slope $\\beta=-0.2\\pm0.3$) likely from dust or old stellar ages. We classify\nthe galaxy SEDs by their restframe $U-V$ and $V-J$ colors and find a diverse\npopulation: $46^{+6+10}_{-6-17}$% of the massive galaxies are quiescent,\n$54^{+8+17}_{-8-10}$% are dusty star-forming galaxies, and only\n$14^{+3+10}_{-3-4}$% resemble luminous blue star forming Lyman break galaxies.\nThis study clearly demonstrates an inherent diversity among massive galaxies at\nhigher redshift than previously known. Furthermore,we uncover a reservoir of\ndusty star-forming galaxies with $4\\times$ lower specific star-formation rates\ncompared to submillimeter-selected starbursts at $z>3$. With $5\\times$ higher\nnumbers, the dusty galaxies may represent a more typical mode of star formation\ncompared to submillimeter-bright starbursts." }, { "anchor": "Simulations of Line Profile Structure in Shell Galaxies: In the context of exploring mass distributions of dark matter haloes in giant\nellipticals, we extend the analysis carried out Merrifield and Kuijken (1998)\nfor stellar line profiles of shells created in nearly radial mergers of\ngalaxies. We show that line-of-sight velocity distributions are more complex\nthan previously predicted. We simulate shell formation and analyze the\ndetectability of spectroscopic signatures of shells after convolution with\nspectral PSFs.", "positive": "Chemodynamically Characterizing the Jhelum Stellar Stream with APOGEE-2: We present the kinematic and chemical profiles of red giant stars observed by\nthe APOGEE-2 survey in the direction of the Jhelum stellar stream, a Milky Way\nsubstructure located in the inner halo of the Milky Way at a distance from the\nSun of $\\approx$ 13 kpc. From the six APOGEE-2 Jhelum pointings, we isolate\nstars with log($g$) $<$ 3.5, leaving a sample of 289 red giant stars. From this\nsample of APOGEE giants, we identified seven stars that are consistent with the\nastrometric signal from $Gaia$ DR2 for this stream. Of these seven, one falls\nonto the RGB along the same sequence as the Jhelum stars presented by\n\\cite{ji20}. This new Jhelum member has [Fe/H]=-2.2 and is at the tip of the\nred giant branch. By selecting high orbital eccentricity, metal-rich stars, we\nidentify red giants in our APOGEE sample that are likely associated with the\n$Gaia$-Enceladus-Sausage (GES) merger. We compare the abundance profiles of the\nJhelum stars and GES stars and find similar trends in $\\alpha$-elements, as\nexpected for low-metallicity populations. However, we find that the orbits for\nGES and Jhelum stars are not generally consistent with a shared origin. The\nchemical abundances for the APOGEE Jhelum star and other confirmed members of\nthe stream are similar to stars in known stellar streams and thus are\nconsistent with an accreted dwarf galaxy origin for the progenitor of the\nstream, although we cannot rule out a globular cluster origin." }, { "anchor": "The WAGGS project - II. The reliability of the calcium triplet as a\n metallicity indicator in integrated stellar light: Using data from the WiFeS Atlas of Galactic Globular cluster Spectra we study\nthe behaviour of the calcium triplet (CaT), a popular metallicity indicator in\nextragalactic stellar population studies. A major caveat of these studies is\nthat the potential sensitivity to other stellar population parameters such as\nage, calcium abundance and the initial mass function has not yet been\nempirically evaluated. Here we present measurements of the strength of the CaT\nfeature for 113 globular clusters in the Milky Way and its satellite galaxies.\nWe derive empirical calibrations between the CaT index and both the iron\nabundance ([Fe/H]) and calcium abundance ([Ca/H]), finding a tighter\nrelationship for [Ca/H] than for [Fe/H]. For stellar populations 3 Gyr and\nolder the CaT can be used to reliably measure [Ca/H] at the 0.1 dex level but\nbecomes less reliable for ages of $\\sim 2$ Gyr and younger. We find that the\nCaT is relatively insensitive to the horizontal branch morphology. The stellar\nmass function however affects the CaT strengths significantly only at low\nmetallicities. Using our newly derived empirical calibration, we convert our\nmeasured CaT indices into [Ca/H] values for the globular clusters in our\nsample.", "positive": "SDSS Absolute Magnitudes for Thin Disc Stars based on Trigonometric\n Parallaxes: We present a new luminosity-colour relation based on trigonometric parallaxes\nfor thin disc main-sequence stars in SDSS photometry. We matched stars from the\nnewly reduced Hipparcos catalogue with the ones taken from 2MASS All-Sky\nCatalogue of Point Sources, and applied a series of constraints, i.e. relative\nparallax errors ($\\sigma_{\\pi}/\\pi\\leq0.05$), metallicity\n($-0.30\\leq[M/H]\\leq0.20$ dex), age ($0\\leq t \\leq 10$ Gyr) and surface gravity\n($\\log g>4$), and obtained a sample of thin disc main-sequence stars. Then, we\nused our previous transformation equations (Bilir et al. 2008a) between SDSS\nand 2MASS photometries and calibrated the $M_{g}$ absolute magnitudes to the\n$(g-r)_{0}$ and $(r-i)_0$ colours. The transformation formulae between 2MASS\nand SDSS photometries along with the absolute magnitude calibration provide\nspace densities for bright stars which saturate the SDSS magnitudes." }, { "anchor": "Star cluster disruption: Star clusters are often used as tracers of major star formation events in\nexternal galaxies as they can be studied up to much larger distances than\nindividual stars. It is vital to understand their evolution if they are used to\nderive, for example, the star formation history of their host galaxy. More\nspecifically, we want to know how cluster lifetimes depend on their environment\nand structural properties such as mass and radius. This review presents a\ntheoretical overview of the early evolution of star clusters and the consequent\nlong term survival chances. It is suggested that clusters forming with initial\ndensities of >10^4 Msun pc-3 survive the gas expulsion, or \"infant mortality\",\nphase. At ~10 Myr they are bound and have densities of 10^{3+/-1} Msun pc-3.\nAfter this time they are stable against expansion by stellar evolution,\nencounters with giant molecular clouds and will most likely survive for another\nHubble time if they are in a moderate tidal field. Clusters with lower initial\ndensities (<100 Msun pc-3) will disperse into the field within a few 10s of\nMyrs. Some discussion is provided on how extra galactic star cluster\npopulations and especially their age distributions can be used to gain insight\nin disruption.", "positive": "Slicing COSMOS with SC4K: the evolution of typical Lya emitters and the\n Lya escape fraction from z~2 to z~6: We present and explore deep narrow- and medium-band data obtained with the\nSubaru and the Isaac Newton telescopes in the ~2 deg$^2$ COSMOS field. We use\nthese data as an extremely wide, low-resolution (R~20-80) IFU survey to slice\nthrough the COSMOS field and obtain a large sample of ~4000 Lyman-$\\alpha$\n(Lya) emitters from z~2 to z~6 in 16 redshift slices (SC4K). We present new Lya\nluminosity functions (LFs) covering a co-moving volume of ~10$^8$Mpc$^3$. SC4K\nextensively complements ultra-deep surveys, jointly covering over 4 dex in Lya\nluminosity and revealing a global (2.53.5, likely\nlinked with the evolution of the AGN population. The Lya luminosity density\nrises by a factor ~2 from z~2 to z~3 but is then found to be roughly constant\n(~$1.1\\times10^{40}$ erg s$^{-1}$ Mpc$^{-3}$) to z~6, despite the ~0.7 dex drop\nin UV luminosity density. The Lya/UV luminosity density ratio rises from\n$4\\pm1$% to $30\\pm6$% from z~2.2 to z~6. Our results imply a rise of a factor\nof ~2 in the global ionisation efficiency ($\\xi_{\\rm ion}$) and a factor\n~$4\\pm1$ in the Lya escape fraction from z~2 to z~6, hinting for evolution in\nboth the typical burstiness/stellar populations and even more so in the typical\nISM conditions allowing Ly$\\alpha$ photons to escape." }, { "anchor": "Downsizing among disk galaxies and the role of the environment: The study of PopI and PopII indicators in galaxies has a profound impact on\nour understanding of galaxy evolution. Their present (z=0) ratio suggests that\nthe star formation history of galaxies was primarily dictated by their global\nmass. Since 1989 Luis Carrasco and I spent most of our sleepless nights\ngathering H_alpha and near infrared surface photometry of galaxies in the local\nUniverse and focused most of our scientific career on these two indicators\ntrying to convince the community that the mass was the key parameter to their\nevolution. We were unsuccessful, until in 2004 the Sloan team rediscovered this\nphenomenon and named it \"downsizing\"", "positive": "Star formation history in the SMC: the case of NGC602: Deep HST/ACS photometry of the young cluster NGC 602, located in the remote\nlow density \"wing\" of the Small Magellanic Cloud, reveals numerous pre-main\nsequence stars as well as young stars on the main sequence. The resolved\nstellar content thus provides a basis for studying the star formation history\ninto recent times and constraining several stellar population properties, such\nas the present day mass function, the initial mass function and the binary\nfraction. To better characterize the pre-main sequence population, we present a\nnew set of model stellar evolutionary tracks for this evolutionary phase with\nmetallicity appropriate for the Small Magellanic Cloud (Z = 0.004). We use a\nstellar population synthesis code, which takes into account a full range of\nstellar evolution phases to derive our best estimate for the star formation\nhistory in the region by comparing observed and synthetic color-magnitude\ndiagrams. The derived present day mass function for NGC 602 is consistent with\nthat resulting from the synthetic diagrams. The star formation rate in the\nregion has increased with time on a scale of tens of Myr, reaching $0.3-0.7\n\\times 10^{-3} M_\\odot yr^{-1}$ in the last 2.5 Myr, comparable to what is\nfound in Galactic OB associations. Star formation is most complete in the main\ncluster but continues at moderate levels in the gas-rich periphery of the\nnebula." }, { "anchor": "First results from the IllustrisTNG simulations: matter and galaxy\n clustering: Hydrodynamical simulations of galaxy formation have now reached sufficient\nvolume to make precision predictions for clustering on cosmologically relevant\nscales. Here we use our new IllustrisTNG simulations to study the non-linear\ncorrelation functions and power spectra of baryons, dark matter, galaxies and\nhaloes over an exceptionally large range of scales. We find that baryonic\neffects increase the clustering of dark matter on small scales and damp the\ntotal matter power spectrum on scales up to k ~ 10 h/Mpc by 20%. The non-linear\ntwo-point correlation function of the stellar mass is close to a power-law over\na wide range of scales and approximately invariant in time from very high\nredshift to the present. The two-point correlation function of the simulated\ngalaxies agrees well with SDSS at its mean redshift z ~ 0.1, both as a function\nof stellar mass and when split according to galaxy colour, apart from a mild\nexcess in the clustering of red galaxies in the stellar mass range 10^9-10^10\nMsun/h^2. Given this agreement, the TNG simulations can make valuable\ntheoretical predictions for the clustering bias of different galaxy samples. We\nfind that the clustering length of the galaxy auto-correlation function depends\nstrongly on stellar mass and redshift. Its power-law slope gamma is nearly\ninvariant with stellar mass, but declines from gamma ~ 1.8 at redshift z=0 to\ngamma ~ 1.6 at redshift z ~ 1, beyond which the slope steepens again. We detect\nsignificant scale-dependencies in the bias of different observational tracers\nof large-scale structure, extending well into the range of the baryonic\nacoustic oscillations and causing nominal (yet fortunately correctable) shifts\nof the acoustic peaks of around ~5%.", "positive": "Synthesizing Stellar Populations in South Pole Telescope Galaxy\n Clusters: I. Ages of Quiescent Member Galaxies at 0.3 < z < 1.4: Using stellar population synthesis models to infer star formation histories\n(SFHs), we analyse photometry and spectroscopy of a large sample of quiescent\ngalaxies which are members of Sunyaev-Zel'dovich (SZ)-selected galaxy clusters\nacross a wide range of redshifts. We calculate stellar masses and mass-weighted\nages for 837 quiescent cluster members at 0.3 < z < 1.4 using rest-frame\noptical spectra and the Python-based Prospector framework, from 61 clusters in\nthe SPT-GMOS Spectroscopic Survey (0.3 < z < 0.9) and 3 clusters in the SPT\nHi-z cluster sample (1.25 < z < 1.4). We analyse spectra of subpopulations\ndivided into bins of redshift, stellar mass, cluster mass, and velocity-radius\nphase-space location, as well as by creating composite spectra of quiescent\nmember galaxies. We find that quiescent galaxies in our dataset sample a\ndiversity of SFHs, with a median formation redshift (corresponding to the\nlookback time from the redshift of observation to when a galaxy forms 50% of\nits mass, t$_{50}$) of $z=2.8\\pm0.5$, which is similar to or marginally higher\nthan that of massive quiescent field and cluster galaxy studies. We also report\nmedian age-stellar mass relations for the full sample (age of the Universe at\n$t_{50}$ (Gyr) = $2.52 (\\pm0.04) - 1.66 (\\pm0.11)$ log$_{10}(M/10^{11}\nM\\odot))$ and recover downsizing trends across stellar mass; we find that\nmassive galaxies in our cluster sample form on aggregate $\\sim0.75$ Gyr earlier\nthan lower mass galaxies. We also find marginally steeper age-mass relations at\nhigh redshifts, and report a bigger difference in formation redshifts across\nstellar mass for fixed environment, relative to formation redshifts across\nenvironment for fixed stellar mass." }, { "anchor": "A Deep Ly$\u03b1$ Survey in ECDF-S and COSMOS: I. General Properties of\n Lyman-alpha Emitters at $z\\sim2$: Ly$\\alpha$ Emitters (LAEs) may represent an important galaxy population in\nthe low mass regime. We present our deep narrowband imaging surveys in the\nCOSMOS and ECDF-S fields and study the properties of LAEs at $z=2.23\\pm0.03$.\nThe narrowband surveys conducted at Magellan II telescope allow us to obtain a\nsample of 452 LAEs reaching a $5\\sigma$ limiting magnitude of $\\sim26$ mag. Our\nLy$\\alpha$ luminosity functions extend to $10^{41.8}$ erg s$^{-1}$ with steep\nfaint-end slope. Using multi-wavelength ancillary data, especially the deep\nSpitzer/IRAC 3.6$\\mu$m and 4.5$\\mu$m photometric data, we obtained reliable\nstellar mass estimates for 130 IRAC-detected LAEs, spanning a range of $8 <\n{\\rm log}(M_\\star/M_\\odot)< 11.5$. For the remaining IRAC-undetected LAEs, the\nmedian-stacked spectral energy distribution yields a stellar mass of ${\\rm\nlog}(M_\\star/M_\\odot)=7.97^{+0.05}_{-0.07}$ and the rest-frame ultraviolet\nemission indicates a median star formation rate of ${\\rm log} (SFR/M_\\odot$\nyr$^{-1})=-0.14\\pm0.35$. There are six LAEs detected by the Spitzer/MIPS\n24$\\mu$m or even Herschel far-infrared observations. Taking into account the\nsix MIR/FIR detected LAEs, our LAEs cover a wide range in the star formation\nrate (${\\rm 1 =10.8^{+0.56}_{-1.1}}$, suggesting\nthat they are progenitors of local Large Magellanic Cloud-like galaxies.", "positive": "Detection of a ~ 0.1c radio knot in M81* associated with a moderate\n X-ray flare: Through very long baseline interferometry observations of one of the closest\nlow-luminosity active galactic nuclei M81* at multifrequencies of 8.8, 22 and\n44GHz, a bright discrete knot with an unusual low apparent speed $\\sim$0.1c was\ndetected. Combining with the contemporary monitoring of X-rays data at 2-10keV,\nit indicates that a moderate X-ray flare happened when the knot launched from\nthe core region. Three possible origins of the knot are proposed to explain our\nobservational results. They are an episodic jet ejection, a low-speed shock\nwave, and a possible secondary black hole in a binary system, respectively.\nFuture intensive multiwavelength monitoring can help to understand the discrete\nknot as well as the central black hole better." }, { "anchor": "The Galactic Thick Disk: An Observational Perspective: In this review, we present a brief description of observational efforts to\nunderstand the Galactic thick disk and its relation to the other Galactic\ncomponents. This review primarily focused on elemental abundance patterns of\nthe thick disk population to pin down the process or processes that were\nresponsible for its existence and evolution. Kinematic and chemical properties\nof disk stars establish that the thick disk is a distinct component in the\nMilky Way. The chemical enrichment and star formation histories hold clues to\nthe bigger picture of understanding the Galaxy formation.", "positive": "The Herschel view of star formation in the Rosette molecular cloud under\n the influence of NGC 2244: The Rosette molecular cloud is promoted as the archetype of a triggered\nstar-formation site. This is mainly due to its morphology, because the central\nOB cluster NGC 2244 has blown a circular-shaped cavity into the cloud and the\nexpanding HII-region now interacts with the cloud. Studying the spatial\ndistribution of the different evolutionary states of all star-forming sites in\nRosette and investigating possible gradients of the dust temperature will help\nto test the 'triggered star-formation' scenario in Rosette. We use continuum\ndata obtained with the PACS (70 and 160 micron) and SPIRE instruments (250,\n350, 500 micron) of the Herschel telescope during the Science Demonstration\nPhase of HOBYS. Three-color images of Rosette impressively show how the\nmolecular gas is heated by the radiative impact of the NGC 2244 cluster. A\nclear negative temperature gradient and a positive density gradient (running\nfrom the HII-region/molecular cloud interface into the cloud) are detected.\nStudying the spatial distribution of the most massive dense cores (size scale\n0.05 to 0.3 pc), we find an age-sequence (from more evolved to younger) with\nincreasing distance to the cluster NGC 2244. No clear gradient is found for the\nclump (size-scale up to 1 pc) distribution. The existence of temperature and\ndensity gradients and the observed age-sequence imply that star formation in\nRosette may indeed be influenced by the radiative impact of the central NGC\n2244 cluster. A more complete overview of the prestellar and protostellar\npopulation in Rosette is required to obtain a firmer result." }, { "anchor": "Radio-loud Narrow Line Seyfert 1 under a different perspective: a\n revised black hole mass estimate from optical spectropolarimetry: Several studies indicate that radio-loud (RL) Active Galactic Nuclei (AGN)\nare produced only by the most massive black holes (BH), $M_{\\rm BH} \\sim\n10^8$-$10^{10} M_\\odot$. This idea has been challenged by the discovery of RL\nNarrow Line Seyfert 1 (RL NLSy1), having estimated masses of $M_{\\rm\nBH}$$\\sim$$10^6$-$10^7$ M$_\\odot$. However, these low $M_{\\rm BH}$ estimates\nmight be due to projection effects. Spectropolarimetry allows us to test this\npossibility by looking at RL NLSy1s under a different perspective, i.e., from\nthe viewing angle of the scattering material. We here report the results of a\npilot study of VLT spectropolarimetric observations of the RL NLSy1 PKS\n2004-447. Its polarization properties are remarkably well reproduced by models\nin which the scattering occurs in an equatorial structure surrounding its broad\nline region, seen close to face-on. In particular, we detect a polarized\nH$\\alpha$ line with a width of $\\sim$ 9,000 km s$^{-1}$, $\\sim 6$ times broader\nthan the width seen in direct light. This corresponds to a revised estimate of\n$M_{\\rm BH}$$\\sim$$6\\times10^8$ M$_\\odot$, well within the typical range of RL\nAGN. The double-peaked polarized broad H$\\alpha$ profile of the target suggests\nthat the rare combination of the orientation effects and a broad line region\ndominated by the rotation might account for this class of objects, casting\ndoubts on the virial estimates of BH mass for type-I AGN.", "positive": "Stellar 3-D kinematics in the Draco dwarf spheroidal galaxy: Aims. We present the first three-dimensional internal motions for individual\nstars in the Draco dwarf spheroidal galaxy. Methods. By combining first-epoch\n$Hubble$ $Space$ $Telescope$ observations and second-epoch $Gaia$ Data Release\n2 positions, we measured the proper motions of $149$ sources in the direction\nof Draco. We determined the line-of-sight velocities for a sub-sample of $81$\nred giant branch stars using medium resolution spectra acquired with the DEIMOS\nspectrograph at the Keck II telescope. Altogether, this resulted in a final\nsample of $45$ Draco members with high-precision and accurate 3D motions, which\nwe present as a table in this paper. Results. Based on this high-quality\ndataset, we determined the velocity dispersions at a projected distance of\n$\\sim120$ pc from the centre of Draco to be $\\sigma_{R} =11.0^{+2.1}_{-1.5}$\nkm/s, $\\sigma_{T}=9.9^{+2.3}_{-3.1}$ km/s and $\\sigma_{LOS}=9.0^{+1.1}_{-1.1}$\nkm/s in the projected radial, tangential, and line-of-sight directions. This\nresults in a velocity anisotropy $\\beta=0.25^{+0.47}_{-1.38}$ at $r \\gtrsim120$\npc. Tighter constraints may be obtained using the spherical Jeans equations and\nassuming constant anisotropy and Navarro-Frenk-White (NFW) mass profiles, also\nbased on the assumption that the 3D velocity dispersion should be lower than\n$\\approx 1/3$ of the escape velocity of the system. In this case, we constrain\nthe maximum circular velocity $V_{max}$ of Draco to be in the range of\n$10.2-17.0$ km/s. The corresponding mass range is in good agreement with\nprevious estimates based on line-of-sight velocities only. Conclusions. Our\nJeans modelling supports the case for a cuspy dark matter profile in this\ngalaxy. Firmer conclusions may be drawn by applying more sophisticated models\nto this dataset and with new datasets from upcoming $Gaia$ releases." }, { "anchor": "The sensitivity of stellar feedback to IMF averaging versus IMF sampling\n in galaxy formation simulations: Galaxy formation simulations frequently use Initial Mass Function (IMF)\naveraged feedback prescriptions, where star particles are assumed to represent\nsingle stellar populations that fully sample the IMF. This approximation breaks\ndown at high mass resolution, where stochastic variations in stellar\npopulations become important. We discuss various schemes to populate star\nparticles with stellar masses explicitly sampled from the IMF. We use Monte\nCarlo numerical experiments to examine the ability of the schemes to reproduce\nan input IMF in an unbiased manner while conserving mass. We present our\npreferred scheme which can easily be added to pre-existing star formation\nprescriptions. We then carry out a series of high resolution isolated\nsimulations of dwarf galaxies with supernovae, photoionization and\nphotoelectric heating to compare the differences between using IMF averaged\nfeedback and explicitly sampling the IMF. We find that if supernovae are the\nonly form of feedback, triggering individual supernovae from IMF averaged rates\ngives identical results to IMF sampling. However, we find that photoionization\nis more effective at regulating star formation when IMF averaged rates are\nused, creating more, smaller H II regions than the rare, bright sources\nproduced by IMF sampling. We note that the increased efficiency of the IMF\naveraged feedback versus IMF sampling is not necessarily a general trend and\nmay be reversed depending on feedback channel, resolution and other details.\nHowever, IMF sampling is always the more physically motivated approach. We\nconservatively suggest that it should be used for star particles less massive\nthan $\\sim500\\,\\mathrm{M_\\odot}$.", "positive": "The Blackhole-Dark Matter Halo Connection: We explore the connection between the central supermassive blackholes (SMBH)\nin galaxies and the dark matter halo through the relation between the masses of\nthe SMBHs and the maximum circular velocities of the host galaxies, as well as\nthe relationship between stellar velocity dispersion of the spheroidal\ncomponent and the circular velocity. Our assumption here is that the circular\nvelocity is a proxy for the mass of the dark matter halo. We rely on a\nheterogeneous sample containing galaxies of all types. The only requirement is\nthat the galaxy has a direct measurement of the mass of its SMBH and a direct\nmeasurement of its circular velocity and its velocity dispersion. Previous\nstudies have analyzed the connection between the SMBH and dark matter halo\nthrough the relationship between the circular velocity and the bulge velocity\ndispersion, with the assumption that the bulge velocity dispersion stands in\nfor the mass of the SMBH, via the well{}-established SMBH mass{}-bulge velocity\ndispersion relation. Using intermediate relations may be misleading when one is\nstudying them to decipher the active ingredients of galaxy formation and\nevolution. We believe that our approach will provide a more direct probe of the\nSMBH and the dark matter halo connection. We find that the correlation between\nthe mass of supermassive blackholes and the circular velocities of the host\ngalaxies is extremely weak, leading us to state the dark matter halo may not\nplay a major role in regulating the blackhole growth in the present Universe." }, { "anchor": "Stellar masses, metallicity gradients and suppressed star formation\n revealed in a new sample of absorption selected galaxies: Context. Absorbing galaxies are selected via the detection of characteristic\nabsorption lines which their gas-rich media imprint in the spectra of distant\nlight-beacons. The proximity of the typically faint foreground absorbing\ngalaxies to bright background sources makes it challenging to robustly identify\nthese in emission, and hence to characterise their relation to the general\ngalaxy population. Aims. We search for emission to confirm and characterise ten\ngalaxies hosting damped, metal-rich quasar absorbers at redshift z < 1.\nMethods. We identify the absorbing galaxies by matching spectroscopic\nabsorption -and emission redshifts and from projected separations. Combining\nemission-line diagnostics with existing absorption spectroscopy and photometry\nof quasar-fields hosting metal-rich, damped absorbers, we compare our new\ndetections with reference samples and place them on scaling relations. Results.\nWe spectroscopically confirm seven galaxies harbouring damped absorbers (a 70%\nsuccess-rate). Our results conform to the emerging picture that neutral gas on\nscales of tens of kpc in galaxies is what causes the characteristic Hi\nabsorption. Our key results are: (I) Absorbing galaxies with $\\log _{10}\n[M_\\star ~(M_\\odot)] \\gtrsim 10$ have star formation rates that are lower than\npredicted for the main sequence of star formation. (II) The distribution of\nimpact parameter with Hi column density and with absorption-metallicity for\nabsorbing galaxies at $z\\sim 2-3$ extends to $z\\sim 0.7$ and to lower Hi column\ndensities. (III) A robust mean metallicity gradient of $\\langle \\Gamma \\rangle\n= 0.022 \\pm 0.001~[dex~kpc^{-1}]$. (IV) By correcting absorption metallicities\nfor $\\langle \\Gamma \\rangle$ and imposing a truncation-radius at\n$12~\\mathrm{kpc}$, absorbing galaxies fall on top of predicted mass-metallicity\nrelations, with a statistically significant decrease in scatter.", "positive": "The physics governing the upper truncation mass of the globular cluster\n mass function: The mass function of globular cluster (GC) populations is a fundamental\nobservable that encodes the physical conditions under which these massive\nstellar clusters formed and evolved. The high-mass end of star cluster mass\nfunctions are commonly described using a Schechter function, with an\nexponential truncation mass $M_{c,*}$. For the GC mass functions in the Virgo\ngalaxy cluster, this truncation mass increases with galaxy mass ($M_{*}$). In\nthis paper we fit Schechter mass functions to the GCs in the most massive\ngalaxy group ($M_{\\mathrm{200}} = 5.14 \\times 10^{13} M_{\\odot}$) in the\nE-MOSAICS simulations. The fiducial cluster formation model in E-MOSAICS\nreproduces the observed trend of $M_{c,*}$ with $M_{*}$ for the Virgo cluster.\nWe therefore examine the origin of the relation by fitting $M_{c,*}$ as a\nfunction of galaxy mass, with and without accounting for mass loss by two-body\nrelaxation, tidal shocks and/or dynamical friction. In the absence of these\nmass-loss mechanisms, the $M_{c,*}$-$M_{*}$ relation is flat above $M_* >\n10^{10} M_{\\odot}$. It is therefore the disruption of high-mass GCs in galaxies\nwith $M_{*}\\sim 10^{10} M_{\\odot}$ that lowers the $M_{c,*}$ in these galaxies.\nHigh-mass GCs are able to survive in more massive galaxies, since there are\nmore mergers to facilitate their redistribution to less-dense environments. The\n$M_{c,*}-M_*$ relation is therefore a consequence of both the formation\nconditions of massive star clusters and their environmentally-dependent\ndisruption mechanisms." }, { "anchor": "Molecular outflow and feedback in the obscured Quasar XID2028 revealed\n by ALMA: We imaged with ALMA and ARGOS/LUCI the molecular gas and the dust and stellar\ncontinuum in XID2028, an obscured QSO at z=1.593, where the presence of a\nmassive outflow in the ionized gas component traced by the [O III]5007 emission\nhas been resolved up to 10 kpc. This target represents a unique test case to\nstudy QSO 'feedback in action' at the peak epoch of AGN-galaxy coevolution. The\nQSO has been detected in the CO(5-4) transition and in the 1.3mm continuum, at\n~30 and ~20 {\\sigma} significance respectively, with both emissions confined in\nthe central (<4 kpc) radius area. Our analysis suggests the presence of a fast\nrotating molecular disc (v~400 km/s) on very compact scales, and well inside\nthe galaxy extent seen in the rest-frame optical light (~10 kpc, as inferred\nfrom the LUCI data). Adding available measurements in additional two CO\ntransitions, CO(2-1) and CO(3-2), we could derive a total gas mass of\n~10$^{10}$ M$_\\odot$, thanks to a critical assessment of CO excitation and the\ncomparison with Rayleigh-Jeans continuum estimate. This translates into a very\nlow gas fraction (<5%) and depletion time scales of 40-75 Myr, reinforcing the\nresult of atypical gas consumption conditions in XID2028, possibly due to\nfeedback effects on the host galaxy. Finally, we also detect at ~5{\\sigma} the\npresence of high velocity CO gas, which we interpret as a signature of\ngalaxy-scale molecular outflow, spatially coincident with the ionised gas\noutflow. XID2028 represents therefore a unique case where the measurement of\ntotal outflowing mass (~500-800 M$_\\odot$/yr) including the molecular and\natomic components, in both the ionised and neutral phases, has been attempted\nfor a high-z QSO.", "positive": "Inquiring into the nature of the Abell 2667 Brightest Cluster Galaxy:\n physical properties from MUSE: Based on HST and MUSE data, we probe the stellar and gas properties (i.e.\nkinematics, stellar mass, star formation rate) of the radio-loud brightest\ncluster galaxy (BCG) located at the centre of the X-ray luminous cool core\ncluster Abell 2667 (z = 0.2343). The bi-dimensional modelling of the BCG\nsurface brightness profile reveals the presence of a complex system of\nsubstructures extending all around the galaxy. Clumps of different size and\nshape plunged into a more diffuse component constitute these substructures,\nwhose intense 'blue' optical colour hints to the presence of a young stellar\npopulation. Our results depict the BCG as a massive (M_star ~ 1.38 x 10^11\nM_sun) dispersion-supported spheroid (v_star < 150 km/s, sigma_0 ~ 216 km/s)\nhosting an active supermassive black hole (M_SMBH ~ 3.8 x 10^9 M_sun) whose\noptical features are typical of low ionisation nuclear emission line regions.\nAlthough the velocity pattern of the stars in the BCG is irregular, the stellar\nkinematics in the regions of the clumps show a positive velocity of ~ 100 km/s,\nsimilarly to the gas component. An analysis of the mechanism giving rise to the\nobserved lines in the clumps through empirical diagnostic diagrams points out\nthat the emission is composite, suggesting the contribution from both star\nformation and AGN. We conclude our analysis describing how scenarios of both\nchaotic cold accretion and merging with a gas-rich disc galaxy can\nefficaciously explain the phenomena the BCG is undergoing." }, { "anchor": "Radio and Far-IR Emission Associated with a Massive Star-forming Galaxy\n Candidate at z$\\simeq$6.8: A Radio-Loud AGN in the Reionization Era?: We report the identification of radio (0.144-3 GHz), mid-IR, far-IR, and\nsub-mm (24-850$\\mu$m) emission at the position of one of 41 UV-bright\n(M$_\\mathrm{UV}^{}\\lesssim-21.25$) $z\\simeq6.6-6.9$ Lyman-break galaxy\ncandidates in the 1.5 deg$^2$ COSMOS field. This source, COS-87259, exhibits a\nsharp flux discontinuity (factor $>$3) between two narrow/intermediate bands at\n9450 and 9700 Angstroms and is undetected in all nine bands blueward of 9600\nAngstroms, as expected from a Lyman-alpha break at $z\\simeq6.8$. The full\nmulti-wavelength (X-ray through radio) data of COS-87529 can be\nself-consistently explained by a very massive (M$_{\\ast}=10^{10.8}$\nM$_{\\odot}$) and extremely red (rest-UV slope $\\beta=-0.59$) $z\\simeq6.8$\ngalaxy with hyperluminous infrared emission (L$_{\\mathrm{IR}}=10^{13.6}$\nL$_{\\odot}$) powered by both an intense burst of highly-obscured star formation\n(SFR$\\approx$1800 M$_{\\odot}$ yr$^{-1}$) and an obscured ($\\tau_{\\mathrm{9.7\\mu\nm}}=7.7\\pm2.5$) radio-loud (L$_{\\mathrm{1.4\\ GHz}}\\approx10^{25.4}$ W\nHz$^{-1}$) AGN. The radio emission is compact (1.04$\\pm$0.12 arcsec) and\nexhibits an ultra-steep spectrum between 1.32-3 GHz\n($\\alpha=-1.57^{+0.22}_{-0.21}$) that flattens at lower frequencies\n($\\alpha=-0.86^{+0.22}_{-0.16}$ between 0.144-1.32 GHz), consistent with known\n$z>4$ radio galaxies. We also demonstrate that COS-87259 may reside in a\nsignificant (11$\\times$) galaxy overdensity at $z\\simeq6.6-6.9$, as common for\nsystems hosting radio-loud AGN. Nonetheless, a spectroscopic redshift will\nultimately be required to establish the true nature of COS-87259 as we cannot\nyet completely rule out low-redshift solutions. If confirmed to lie at\n$z\\simeq6.8$, the properties of COS-87259 would be consistent with a picture\nwherein AGN and highly-obscured star formation activity are fairly common among\nvery massive (M$_{\\ast}>10^{10}$ M$_{\\odot}$) reionization-era galaxies.", "positive": "The MASSIVE Survey XIV -- Stellar Velocity Profiles and Kinematic\n Misalignments from 200 pc to 20 kpc in Massive Early-type Galaxies: We use high spatial resolution stellar velocity maps from the Gemini GMOS\nintegral-field spectrograph (IFS) and wide-field velocity maps from the\nMcDonald Mitchell IFS to study the stellar velocity profiles and kinematic\nmisalignments from $\\sim 200$ pc to $\\sim 20$ kpc in 20 early-type galaxies\nwith stellar mass $M_* > 10^{11.7} M_\\odot$ in the MASSIVE survey. While 80% of\nthe galaxies have low spins ($\\lambda < 0.1$) and low rotational velocities ($<\n50$ km/s) in both the central region and the main body, we find a diverse range\nof velocity features and misalignment angles. For the 18 galaxies with\nmeasurable central kinematic axes, 10 have well aligned kinematic axis and\nphotometric major axis, and the other 8 galaxies have misalignment angles that\nare distributed quite evenly from $15^\\circ$ to the maximal value of\n$90^\\circ$. There is a strong correlation between central kinematic\nmisalignment and galaxy spin, where all 4 galaxies with significant spins have\nwell aligned kinematic and photometric axes, but only 43% of the low-spin\ngalaxies are well aligned. The central and main-body kinematic axes within a\ngalaxy are not always aligned. When the two kinematic axes are aligned ($\\sim\n60$% of the cases), they are either also aligned with the photometric major\naxis or orthogonal to it. We find 13 galaxies to also exhibit noticeable local\nkinematic twists, and one galaxy to have a counter-rotating core. A diverse\nassembly history consisting of multiple gas-poor mergers of a variety of\nprogenitor mass ratios and orbits is likely to be needed to account for the\npredominance of low spins and the wide range of central and main-body velocity\nfeatures reported here for local massive ETGs." }, { "anchor": "First results from the JWST Early Release Science Program Q3D: Benchmark\n Comparison of Optical and Mid-IR Tracers of a Dusty, Ionized Red Quasar Wind\n at z=0.435: The [OIII] 5007 A emission line is the most common tracer of warm, ionized\noutflows in active galactic nuclei across cosmic time. JWST newly allows us to\nuse mid-infrared spectral features at both high spatial and spectral resolution\nto probe these same winds. Here we present a comparison of ground-based,\nseeing-limited [OIII] and space-based, diffraction-limited [SIV] 10.51 micron\nmaps of the powerful, kiloparsec-scale outflow in the Type 1 red quasar SDSS\nJ110648.32+480712.3. The JWST data are from the Mid-InfraRed Instrument (MIRI).\nThere is a close match in resolution between the datasets (0.\"6), in ionization\npotential of the O$^{+2}$ and S$^{+3}$ ions (35 eV), and in line sensitivity\n(1e-17 to 2e-17 erg/s/cm$^2$/arcsec$^2$). The [OIII] and [SIV] line shapes\nmatch in velocity and linewidth over much of the 20 kpc outflowing nebula, and\n[SIV] is the brightest line in the rest-frame 3.5-19.5 micron range,\ndemonstrating its usefulness as a mid-IR probe of quasar outflows. [OIII] is\nnevertheless intriniscally brighter and provides better contrast with the\npoint-source continuum, which is strong in the mid-IR. There is a strong\nanticorrelation of [OIII]/[SIV] with average velocity, which is consistent with\na scenario of differential obscuration between the approaching (blueshifted)\nand receding (redshifted) sides of the flow. The dust in the wind may also\nobscure the central quasar, consistent with models that attribute red quasar\nextinction to dusty winds.", "positive": "Toward Astrometric Constraints on a Supermassive Black Hole Binary in\n the Early-Type Galaxy NGC\\,4472: The merger of two galaxies, each hosting a supermassive black hole (SMBH) of\nmass $10^6$\\,M$_{\\odot}$ or more, could yield a bound SMBH binary. For the\nearly-type galaxy NGC\\,4472, we study how astrometry with a next-generation\nVery Large Array (ngVLA) could be used to monitor the reflex motion of the\nprimary SMBH of mass $M_{\\rm pri}$, as it is tugged on by the secondary SMBH of\nmass $M_{\\rm sec}$. Casting the orbit of the putative SMBH binary in terms of\nits period $P$, semimajor axis $a_{\\rm bin}$, and mass ratio $q = M_{\\rm sec} /\nM_{\\rm pri} \\le 1$, we find the following: (1) Orbits with fiducial periods of\n$P = 4$\\,yr and 40\\,yr could be spatially resolved and monitored. (2) For a\n95\\% accuracy of $2\\,\\mu$as per monitoring epoch, sub-parsec values of $a_{\\rm\nbin}$ could be accessed over a range of mass ratios notionally encompassing\nmajor ($q > \\frac{1}{4}$) and minor ($q < \\frac{1}{4}$) galaxy mergers. (3) If\nno reflex motion is detected for $M_{\\rm pri}$ after 1(10)\\,yr of monitoring, a\nSMBH binary with period $P = 4(40)$\\,yr and mass ratio $q > 0.01(0.003)$ could\nbe excluded. This would suggest no present-day evidence for a past major merger\nlike that recently simulated, where scouring by a $q \\sim 1$ SMBH binary formed\na stellar core with kinematic traits like those of NGC\\,4472. (4) Astrometric\nmonitoring could independently check the upper limits on $q$ from searches for\ncontinuous gravitational waves from NGC\\,4472." }, { "anchor": "AGNs at the cosmic dawn: predictions for future surveys from a\n $\u039b$CDM cosmological model: Telescopes to be launched over the next decade-and-a-half, such as JWST,\nEUCLID, ATHENA and Lynx, promise to revolutionise the study of the high\nredshift Universe and greatly advance our understanding of the early stages of\ngalaxy formation. We use a model that follows the evolution of the masses and\nspins of supermassive black holes (SMBHs) within a semi-analytic model of\ngalaxy formation to make predictions for the Active Galactic Nucleus (AGN)\nluminosity function at $z\\geq7$ in the broadband filters of JWST and EUCLID at\nnear-infrared wavelengths, and ATHENA and Lynx at X-ray energies. The\npredictions of our model are relatively insensitive to the choice of seed black\nhole mass, except at the lowest luminosities\n($L_{\\mathrm{bol}}<10^{43}\\mathrm{ergs^{-1}}$) and the highest redshifts\n($z>10$). We predict that surveys with these different telescopes will select\nsomewhat different samples of SMBHs, with EUCLID unveiling the most massive,\nhighest accretion rate SMBHs, Lynx the least massive, lowest accretion rate\nSMBHs, and JWST and ATHENA covering objects inbetween. At $z=7$, we predict\nthat typical detectable SMBHs will have masses,\n$M_{\\mathrm{BH}}\\sim10^{5-8}M_{\\odot}$, and Eddington normalised mass accretion\nrates, $\\dot{M}/\\dot{M}_{\\mathrm{Edd}}\\sim0.6-2$. The SMBHs will be hosted by\ngalaxies of stellar mass $M_{\\star}\\sim10^{8-10}M_{\\odot}$, and dark matter\nhaloes of mass $M_{\\mathrm{halo}}\\sim10^{11-12}M_{\\odot}$. We predict that the\ndetectable SMBHs at $z=10$ will have slightly smaller black holes, accreting at\nslightly higher Eddington normalised mass accretion rates, in slightly lower\nmass host galaxies compared to those at $z=7$, and reside in haloes of mass\n$M_{\\mathrm{halo}}\\sim10^{10-11}M_{\\odot}$.", "positive": "The gMOSS: the galaxy survey and galaxy populations of the large\n homogeneous field: We present the gMOSS (Galaxies of Medium-band One-meter Schmidt telescope\nSurvey) catalog of $\\sim$ 19,000 galaxies in 20 filters (4 broadband SDSS and\n16 medium-band filters). We observed 2.386 $\\mathrm{deg^2}$ on the central part\nof the HS47.5-22 field with the 1-m Schmidt telescope of the Byurakan\nAstrophysical Observatory. The gMOSS is a complete flux-limited sample of\ngalaxies with a threshold magnitude of $r$ SDSS $\\le$ 22.5 AB. From photometric\nmeasurements with 16 medium-band filters and $u$ SDSS, we get spectral energy\ndistributions for each object in the field, which are used for further\nanalysis. Galaxy classification and photometric redshift estimation based on\nspectral template matching with ZEBRA software. The obtained redshift accuracy\nis $\\sigma_\\mathrm{{NMAD}} < 0.0043$. Using the SED-fitting CIGALE code, we\nobtained the main properties of the stellar population of galaxies, such as\nrest-frame $(u - r)_{\\mathrm{res}}$ colour, stellar mass, extinction, and\nmass-weighted age with a precision of $0.16 \\pm 0.07$ mag, $0.14 \\pm 0.04$ dex,\n$0.27 \\pm 0.1$ mag, and $0.08 \\pm 0.04$ dex, respectively. Using a\ndust-corrected colour-mass diagram, we divided the full sample into populations\nof red and blue galaxies and considered the dependencies between stellar mass\nand age. Throughout cosmic time, red sequence galaxies remain older and more\nmassive than blue cloud galaxies. The star formation history of a complete\nsubsample of galaxies selected in the redshift range $0.05\\le z\\le0.015$ with\n<$\\mathrm{log} M \\mathrm{>}_\\mathrm{[M_\\odot]}$>8.3 shows an increase in the\nSFRD up to $z\\sim3$, under the results obtained in earlier studies." }, { "anchor": "The ages, metallicities and element abundance ratios of massive quenched\n galaxies at z~1.6: We investigate the stellar population properties of a sample of 24 massive\nquenched galaxies at $1.257 the\nmajority of galaxies detected with Ly$\\alpha$ are in candidate overdensities.\nHere we quantify the probability of these galaxies residing in large ionised\nbubbles. We create (1.6 Gpc)$^3$ reionising intergalactic medium (IGM)\nsimulations, providing sufficient volume to robustly measure bubble size\ndistributions around UV-bright galaxies and rare overdensities. We find $M_{\\rm\nUV} \\lesssim -16$ galaxies and overdensities are $\\gtrsim$10-1000x more likely\nto trace ionised bubbles compared to randomly selected positions. The brightest\ngalaxies and strongest overdensities have bubble size distributions with\nhighest characteristic size and least scatter. We compare two models: gradual\nreionisation driven by numerous UV-faint galaxies versus more rapid\nreionisation by rarer brighter galaxies, producing larger bubbles at fixed\nneutral fraction. We demonstrate that recently observed z~7 overdensities are\nhighly likely to trace large ionised bubbles, corroborated by their high\nLy$\\alpha$ detection rates. However, the z~8.7 association of Ly$\\alpha$\nemitters in EGS and GN-z11, with Ly$\\alpha$ at z=10.6, are unlikely to trace\nlarge bubbles in our fiducial model -- 11% and 7% probability of >1 proper Mpc\nbubbles, respectively. Ly$\\alpha$ detections at such high redshifts could be\nexplained by: a less neutral IGM than previously expected; larger ionised\nregions at fixed neutral fraction; or if intrinsic Ly$\\alpha$ flux is unusually\nstrong in these galaxies. We discuss how to test these scenarios with JWST and\nthe prospects for using upcoming wide-area surveys to distinguish between\nreionisation models.", "positive": "Croatian Black Hole School 2010 lecture notes on IMBHs in GCs: Black holes are fascinating objects. As a class of solutions to the Einstein\nequations they have been studied a great deal, yielding a wealth of theoretical\nresults. But do they really exist? What do astronomers really mean when they\nclaim to have observational evidence of their existence? To answer these\nquestions, I will focus on a particular range of black-hole masses,\napproximately from 100 to 10000 solar masses. Black holes of this size are\nnamed Intermediate Mass Black Holes (IMBHs) and their existence is still\nheavily disputed, so they will be perfect for illustrating the observational\nchallenges faced by a black hole hunter" }, { "anchor": "Atomic and molecular gas in IllustrisTNG galaxies at low redshift: We have recently developed a post-processing framework to estimate the\nabundance of atomic and molecular hydrogen (HI and H2, respectively) in\ngalaxies in large-volume cosmological simulations. Here we compare the HI and\nH2 content of IllustrisTNG galaxies to observations. We mostly restrict this\ncomparison to $z \\approx 0$ and consider six observational metrics: the overall\nabundance of HI and H2, their mass functions, gas fractions as a function of\nstellar mass, the correlation between H2 and star formation rate, the spatial\ndistribution of gas, and the correlation between gas content and morphology. We\nfind generally good agreement between simulations and observations,\nparticularly for the gas fractions and the HI mass-size relation. The H2 mass\ncorrelates with star formation rate as expected, revealing an almost constant\ndepletion time that evolves up to z = 2 as observed. However, we also discover\na number of tensions with varying degrees of significance, including an\noverestimate of the total neutral gas abundance at z = 0 by about a factor of\ntwo and a possible excess of satellites with no or very little neutral gas.\nThese conclusions are robust to the modelling of the HI/H2 transition. In terms\nof their neutral gas properties, the IllustrisTNG simulations represent an\nenormous improvement over the original Illustris run. All data used in this\npaper are publicly available as part of the IllustrisTNG data release.", "positive": "The global gas and dust budget of the Small Magellanic Cloud: In order to understand the evolution of the interstellar medium (ISM) of a\ngalaxy, we have analysed the gas and dust budget of the Small Magellanic Cloud\n(SMC). Using the Spitzer Space Telescope, we measured the integrated gas\nmass-loss rate across asymptotic giant branch (AGB) stars and red supergiants\n(RSGs) in the SMC, and obtained a rate of 1.4x10^-3 Msun yr-1. This is much\nsmaller than the estimated gas ejection rate from type II supernovae (SNe)\n(2-4x10^-2 Msun yr-1). The SMC underwent a an increase in starformation rate in\nthe last 12 Myrs, and consequently the galaxy has a relatively high SN rate at\npresent. Thus, SNe are more important gas sources than AGB stars in the SMC.\nThe total gas input from stellar sources into the ISM is 2-4x10^-2 Msun yr-1.\nThis is slightly smaller than the ISM gas consumed by starformation (~8x10^-2\nMsun yr-1). Starformation in the SMC relies on a gas reservoir in the ISM, but\neventually the starformation rate will decline in this galaxy, unless gas\ninfalls into the ISM from an external source. The dust injection rate from AGB\nand RSG candidates is 1x10^-5 Msun yr-1. Dust injection from SNe is in the\nrange of 0.2--11x10^-4 Msun yr-1, although the SN contribution is rather\nuncertain. Stellar sources could be important for ISM dust (3x10^5 Msun yr-1)\nin the SMC, if the dust lifetime is about 1.4 Gyrs. We found that the presence\nof poly-aromatic hydrocarbons (PAHs) in the ISM cannot be explained entirely by\ncarbon-rich AGB stars. Carbon-rich AGB stars could inject only 7x10^-9 Msun\nyr-1 of PAHs at most, which could contribute up to 100 Msun of PAHs in the\nlifetime of a PAH. The estimated PAH mass of 1800 Msun in the SMC can not be\nexplained. Additional PAH sources, or ISM reprocessing should be needed." }, { "anchor": "Simulating Jellyfish Galaxies: A Case Study for a Gas-Rich Dwarf Galaxy: We investigate the formation of jellyfish galaxies using\nradiation-hydrodynamic simulations of gas-rich dwarf galaxies with a\nmulti-phase interstellar medium (ISM). We find that the ram-pressure-stripped\n(RPS) ISM is the dominant source of molecular clumps in the near wake within 10\nkpc from the galactic plane, while in-situ formation is the major channel for\ndense gas in the distant tail of the gas-rich galaxy. Only 20% of the molecular\nclumps in the near wake originate from the intracluster medium (ICM); however,\nthe fraction reaches 50% in the clumps located at $80\\,{\\rm kpc}$ from the\ngalactic center since the cooling time of the RPS gas tends to be short due to\nthe ISM--ICM mixing ($\\lesssim$ 10 Myr). The tail region exhibits a star\nformation rate of $0.001-0.01\\,{\\rm M_{\\odot}\\,yr^{-1}}$, and most of the tail\nstars are born in the stripped wake within 10 kpc from the galactic plane.\nThese stars induce bright H$\\alpha$ blobs in the tail, while H$\\alpha$ tails\nfainter than $6\\times10^{38}\\,{\\rm erg\\,s^{-1}\\,kpc^{-2}}$ are mostly formed\nvia collisional radiation and heating due to mixing. We also find that the\nstripped tails have intermediate X-ray to H$\\alpha$ surface brightness ratios\n(1.5$\\lesssim F_{\\rm X}/F_{\\rm H\\alpha}\\lesssim$20), compared to the ISM\n($\\lesssim$1.5) or pure ICM ($\\gg$20). Our results suggest that jellyfish\nfeatures emerge when the ISM from gas-rich galaxies is stripped by strong ram\npressure, mixes with the ICM, and enhances the cooling in the tail.", "positive": "Tracing Dark Matter Halos with Satellite Kinematics and the Central\n Stellar Velocity Dispersion of Galaxies: It has been suggested that the central stellar velocity dispersion of\ngalaxies can trace dark matter halo mass directly. We test this hypothesis\nusing a complete spectroscopic sample of isolated galaxies surrounded by faint\nsatellite galaxies from the Sloan Digital Sky Survey Data Release 12. We apply\na friends-of-friends algorithm with projected linking length $\\Delta D < 100$\nkpc and radial velocity linking length $\\Delta V < 1000$ km s$^{-1}$ to\nconstruct our sample. Our sample includes 2807 isolated galaxies with 3417\nsatellite galaxies at $0.01 < z < 0.14$. We divide the sample into two groups\nbased on the primary galaxy color: red and blue primary galaxies separated at\n$(g-r)_{0} = 0.85$. The central stellar velocity dispersions of the primary\ngalaxies are proportional to the luminosities and stellar masses of the same\ngalaxies. Stacking the sample based on the central velocity dispersion of the\nprimary galaxies, we derive the velocity dispersions of their satellite\ngalaxies, which trace the dark matter halo mass of the primary galaxies. The\nsystem velocity dispersion of the satellite galaxies shows a remarkably tight\ncorrelation with the central velocity dispersion of the primary galaxies for\nboth red and blue samples. In particular, the slope of the relation is\nidentical to 1 for red primary systems. This tight relation suggests that the\ncentral stellar velocity dispersion of galaxies is indeed an efficient and\nrobust tracer for dark matter halo mass. We provide empirical relations between\nthe central stellar velocity dispersion and the dark matter halo mass." }, { "anchor": "Revisiting a detached stellar structure in the outer northeastern region\n of the Small Magellanic Cloud: The outer northeastern region of the Small Magellanic Cloud (SMC) is\npopulated by a shell-like overdensity whose nature was recently investigated.\nWe analyzed twenty catalogued star clusters projected onto it from Survey of\nthe MAgellanic Stellar History data sets. After carrying out a cleaning of\nfield stars in the star cluster colour-magnitude diagrams (CMDs), and deriving\ntheir astrophysical properties from the comparison between the observed and\nsynthetic CMDs, we found that four objects are not genuine star clusters, while\nthe remaining ones are young star clusters (11, age $\\sim$ 30-200 Myr) and\nintermediate-age (5, age $\\sim$ 1.7-2.8 Gyr) star clusters, respectively. The\nresulting distances show that intermediate-age and some young star clusters\nbelong to the SMC main body, while the remaining young star clusters are nearly\n13.0 kpc far away from those in the SMC, revealing that the shell-like\noverdensity is more extended along the line-of-sight than previously thought.\nWe also found a clear age trend and a blurred metallicity correlation along the\nline-of-sight of young clusters, in the sense that the farther a star cluster\nfrom the SMC, the younger, the more metal rich, and the less massive it is.\nThese young clusters are also affected by a slightly larger interstellar\nreddening than the older ones in the shell-like overdensity. These outcomes\nsuggest that the shell-like overdensity can possibly be another tidally\nperturbed/formed SMC stellar structure from gas striped off its body, caused by\nthe interaction with the Large Magellanic Cloud or the Milky Way.", "positive": "JWST discovers an AGN ionization cone but only weak radiative-driven\n feedback in a powerful $z$$\\approx$3.5 radio-loud AGN: We present the first results from a JWST program studying the role played by\npowerful radio jets in the evolution of the most massive galaxies at the onset\nof Cosmic Noon. Using NIRSpec integral field spectroscopy, we detect 24\nrest-frame optical emission lines from the $z=3.5892$ radio galaxy 4C+19.71.\n4C+19.71 contains one of the most energetic radio jets known, making it perfect\nfor testing radio-mode feedback on the interstellar medium (ISM) of a\n$M_{\\star}\\sim10^{11}\\,\\rm M_{\\odot}$ galaxy. The rich spectrum enables line\nratio diagnostics showing that the radiation from the active galactic nucleus\n(AGN) dominates the ionization of the entire ISM out to at least $25\\,$kpc, the\nedge of the detection. Sub-kpc resolution reveals filamentary structures and\nemission blobs in the warm ionized ISM distributed on scales of $\\sim5$ to\n$\\sim20\\,$kpc. A large fraction of the extended gaseous nebula is located near\nthe systemic velocity. This nebula may thus be the patchy ISM which is\nilluminated by the AGN after the passage of the jet. A radiatively-driven\noutflow is observed within $\\sim5\\,$kpc from the nucleus. The inefficient\ncoupling ($\\lesssim 10^{-4}$) between this outflow and the quasar and the lack\nof extreme gas motions on galactic scales are inconsistent with other high-$z$\npowerful quasars. Combining our data with ground-based studies, we conclude\nthat only a minor fraction of the feedback processes is happening on $<25\\,$kpc\nscales." }, { "anchor": "A comprehensive rotational study of astronomical iso-pentane within 84\n to 111 GHz: The rotational line survey by ALMA (Atacama Large Millimeter/submillimeter\nArray) recently revealed the presence of i-C3H7CN (i-PrCN) and n-C3H7CN\n(n-PrCN) in 3-mm atmospheric window between 84 to 111 GHz towards the hot core\nregion Sagittarius B2(N) (Sgr B2(N)). This was the first interstellar detection\nof a linear straight chain molecule. In this light, we report the rotational\nspectra of C5H12 isomeric group in the same frequency range. We performed\nquantum chemical calculations for spectroscopic parameters. The pure rotational\nspectrum of the species has been simulated using the PGOPHER program. The\nrotational spectrum of this molecule makes it a good candidate for future\nastronomical detections since the radio lines can be calculated to very high\naccuracy in mm/sub-mm wave region.", "positive": "Peeking beneath the precision floor I: metallicity spreads and multiple\n elemental dispersions in the globular clusters NGC 288 and NGC 362: The view of globular clusters (GCs) as simple systems continues to unravel,\nrevealing complex objects hosting multiple chemical peculiarities. Using\ndifferential abundance analysis, we probe the chemistry of the Type I GC, NGC\n288 and the Type II GC, NGC 362 at the 2\\% level for the first time. We measure\n20 elements and find differential measurement uncertainties on the order\n0.01-0.02 dex in both clusters. The smallest uncertainties are measured for Fe\nI in both clusters, with an average uncertainty of $\\sim$0.013 dex. Dispersion\nin the abundances of Na, Al, Ti I, Ni, Fe I, Y, Zr, Ba and Nd are recovered in\nNGC 288, none of which can be explained by a spread in He. This is the first\ntime, to our knowledge, a statistically significant spread in $s$-process\nelements and a potential spread in metallicity has been detected in NGC 288. In\nNGC 362, we find significant dispersion in the same elements as NGC 288, with\nthe addition of Co, Cu, Zn, Sr, La, Ce, and Eu. Two distinct groups are\nrecovered in NGC 362, separated by 0.3 dex in average differential $s$-process\nabundances. Given strong correlations between Al and several $s$-process\nelements, and a significant correlation between Mg and Si, we propose that the\n$s$-process rich group is younger. This agrees with asymptotic giant branch\nstar (AGB) enrichment between generations, if there is overlap between low- and\nintermediate-mass AGBs. In our scenario, the older population is dominated by\nthe $r$-process with a $\\Delta^{\\mathrm{La}}-\\Delta^{\\mathrm{Eu}}$ ratio of\n$-0.16\\pm0.06$. We propose that the $r$-process dominance and dispersion found\nin NGC 362 are primordial." }, { "anchor": "J01020100-7122208: an accreted evolved blue straggler that wasn't\n ejected from a supermassive black hole: J01020100-7122208 is a star whose origin and nature still challenges us. It\nwas first believed to be a yellow super giant ejected from the Small Magellanic\nCloud, but it was more recently claimed to be a red giant accelerated by the\nMilky Way's central black hole. In order to unveil its nature, we analysed\nphotometric, astrometric and high resolution spectroscopic observations to\nestimate the orbit, age, and 16 elemental abundances. Our results show that\nthis star has a retrograde and highly-eccentric orbit,\n$e=0.914_{-0.020}^{+0.016}$. Correspondingly, it likely crossed the Galactic\ndisk at $550\\;\\mathrm{pc}$ from the Galactic centre. We obtained a\nspectroscopic mass and age of $1.09\\pm0.10$ $M_\\odot$ and $4.51\\pm1.44$ Gyr\nrespectively. Its chemical composition is similar to the abundance of other\nretrograde halo stars. We found that the star is enriched in europium, having\n[Eu/Fe] = 0.93 $\\pm$ 0.24, and is more metal-poor than reported in the\nliterature, with [Fe/H] = -1.30 $\\pm$ 0.10. This information was used to\nconclude that J01020100-7122208 is likely not a star ejected from the central\nblack of the Milky Way or from the Small Magellanic Cloud. Instead, we propose\nthat it is simply a halo star which was likely accreted by the Milky Way in the\ndistant past but its mass and age suggest it is probably an evolved blue\nstraggler.", "positive": "Herschel/HIFI observations of spectrally resolved methylidyne signatures\n toward the high-mass star-forming core NGC6334I: In contrast to extensively studied dense star-forming cores, little is known\nabout diffuse gas surrounding star-forming regions. We study molecular gas in\nthe high-mass star-forming region NGC6334I, which contains diffuse, quiescent\ncomponents that are inconspicuous in widely used molecular tracers such as CO.\nWe present Herschel/HIFI observations of CH toward NGC6334I observed as part of\nthe CHESS key program. HIFI resolves the hyperfine components of its J=3/2-1/2\ntransition, observed in both emission and absorption. The CH emission appears\nclose to the systemic velocity of NGC6334I, while its measured linewidth of 3\nkm/s is smaller than previously observed in dense gas tracers such as NH3 and\nSiO. The CH abundance in the hot core is 7 10^-11, two to three orders of\nmagnitude lower than in diffuse clouds. While other studies find distinct\noutflows in, e.g., CO and H2O toward NGC6334I, we do not detect outflow\nsignatures in CH. To explain the absorption signatures, at least two absorbing\ncomponents are needed at -3.0 and +6.5 km/s with N(CH)=7 10^13 and 3 10^13\ncm^-2. Two additional absorbing clouds are found at +8.0 and 0.0 km/s, both\nwith N(CH)=2 10^13 cm^-2. Turbulent linewidths for the four absorption\ncomponents vary between 1.5 and 5.0 km/s in FWHM. We constrain physical\nproperties of our CH clouds by matching our CH absorbers with other absorption\nsignatures. In the hot core, molecules such as H2O and CO trace gas that is\nheated and dynamically influenced by outflow activity, whereas CH traces more\nquiescent material. The four CH absorbers have column densities and turbulent\nproperties consistent with diffuse clouds: two are located near NGC6334, and\ntwo are unrelated foreground clouds. Local density and dynamical effects\ninfluence the chemical composition of physical components of NGC6334, causing\nsome components to be seen in CH but not in other tracers, and vice versa." }, { "anchor": "Velocity Dispersion, Size, S\u00e9rsic Index and $D_n4000$: The Scaling of\n Stellar Mass with Dynamical Mass for Quiescent Galaxies: We examine the relation between stellar mass, velocity dispersion, size,\nS\\'ersic index and $D_n4000$ for ~40,000 quiescent galaxies in the SDSS. At a\nfixed stellar mass, galaxies with higher $D_n4000$ have larger velocity\ndispersions and smaller sizes. $D_n4000$ is a proxy for stellar population age,\nthus these trends suggest that older galaxies typically have larger velocity\ndispersions and smaller sizes. We combine velocity dispersion and size into a\ndynamical mass estimator, $\\sigma^2 R$. At a fixed stellar mass, $\\sigma^2 R$\ndepends on $D_n4000$. The S\\'ersic index is also correlated with $D_n4000$. The\ndependence of $\\sigma^2 R$ and S\\'ersic index on $D_n4000$ suggests that\nquiescent galaxies are not structurally homologous systems. We derive an\nempirical correction for non-homology which is consistent with the analytical\ncorrection derived from the virial theorem. After accounting for non-homologous\ngalactic structure, we measure $M_\\ast \\propto M_d^{0.998 \\pm 0.004}$ where\n$M_\\ast$ is the stellar mass and $M_d$ is the dynamical mass derived from the\nvelocity dispersion and size; stellar mass is directly proportional to\ndynamical mass. Quiescent galaxies appear to be in approximate virial\nequilibrium and deviations of the fundamental plane parameters from the\nexpected virial relation may result from mass-to-light ratio variations,\nselection effects and the non-homology of quiescent galaxies. We infer the\nredshift evolution of velocity dispersion and size for galaxies in our sample\nassuming purely passive evolution. The inferred evolution is inconsistent with\ndirect measurements at higher redshifts. Thus quiescent galaxies do not\npassively evolve. Quiescent galaxies have properties consistent with standard\ngalaxy formation in $\\Lambda$CDM. They form at different epochs and evolve\nmodestly increasing their size, velocity dispersion and S\\'ersic index after\nthey cease star formation.", "positive": "A Non-Equilibrium Ionization Model of the Local and Loop I Bubbles -\n Tracing the Ovi Distribution: We present the first to date three-dimensional high-resolution hydrodynamical\nsimulation tracing the non-equilibrium ionization evolution (using the Eborae\nAtomic and Molecular Plasma Emission Code - E(A+M)PEC) of the Local Bubble and\nLoop I superbubbles embedded in a turbulent supernova-driven interstellar\nmedium." }, { "anchor": "Automated Detection of Double Nuclei Galaxies using GOTHIC and the\n Discovery of a Large Sample of Dual AGN: We present a novel algorithm to detect double nuclei galaxies (DNG) called\nGOTHIC (Graph BOosted iterated HIll Climbing) - that detects whether a given\nimage of a galaxy has two or more closely separated nuclei. Our aim is to\ndetect samples of dual or multiple active galactic nuclei (AGN) in galaxies.\nAlthough galaxy mergers are common, the detection of dual AGN is rare. Their\ndetection is very important as they help us understand the formation of\nsupermassive black hole (SMBH) binaries, SMBH growth and AGN feedback effects\nin multiple nuclei systems. There is thus a need for an algorithm to do a\nsystematic survey of existing imaging data for the discovery of DNGs and dual\nAGN. We have tested GOTHIC on a known sample of DNGs and subsequently applied\nit to a sample of a million SDSS DR16 galaxies lying in the redshift range of 0\nto 0.75 approximately, and have available spectroscopic data. We have detected\n159 dual AGN in this sample, of which 2 are triple AGN systems. Our results\nshow that dual AGN are not common, and triple AGN even rarer. The color (u-r)\nmagnitude plots of the DNGs indicate that star formation is quenched as the\nnuclei come closer and as the AGN fraction increases. The quenching is\nespecially prominent for dual/triple AGN galaxies that lie in the extreme end\nof the red sequence.", "positive": "Wolf-Rayet stars in the Antennae unveiled by MUSE: We present the analysis of archival Very Large Telescope (VLT) Multi Unit\nSpectroscopic Explorer (MUSE) observations of the interacting galaxies NGC\n4038/39 (a.k.a. the Antennae) at a distance of 18.1 Mpc. Up to 38 young\nstar-forming complexes with evident contribution from Wolf-Rayet (WR) stars are\nunveiled. We use publicly available templates of Galactic WR stars in\nconjunction with available photometric extinction measurements to quantify and\nclassify the WR population in each star-forming region, on the basis of its\nnearly Solar oxygen abundance. The total estimated number of WR stars in the\nAntennae is 4053 $\\pm$ 84, of which there are 2021 $\\pm$ 60 WNL and 2032 $\\pm$\n59 WC-types. Our analysis suggests a global WC to WN-type ratio of 1.01 $\\pm$\n0.04, which is consistent with the predictions of the single star evolutionary\nscenario in the most recent BPASS stellar population synthesis models." }, { "anchor": "CNN Architecture Comparison for Radio Galaxy Classification: The morphological classification of radio sources is important to gain a full\nunderstanding of galaxy evolution processes and their relation with local\nenvironmental properties. Furthermore, the complex nature of the problem, its\nappeal for citizen scientists and the large data rates generated by existing\nand upcoming radio telescopes combine to make the morphological classification\nof radio sources an ideal test case for the application of machine learning\ntechniques. One approach that has shown great promise recently is Convolutional\nNeural Networks (CNNs). Literature, however, lacks two major things when it\ncomes to CNNs and radio galaxy morphological classification. Firstly, a proper\nanalysis of whether overfitting occurs when training CNNs to perform radio\ngalaxy morphological classification using a small curated training set is\nneeded. Secondly, a good comparative study regarding the practical\napplicability of the CNN architectures in literature is required. Both of these\nshortcomings are addressed in this paper. Multiple performance metrics are used\nfor the latter comparative study, such as inference time, model complexity,\ncomputational complexity and mean per class accuracy. As part of this study we\nalso investigate the effect that receptive field, stride length and coverage\nhas on recognition performance. For the sake of completeness, we also\ninvestigate the recognition performance gains that we can obtain by employing\nclassification ensembles. A ranking system based upon recognition and\ncomputational performance is proposed. MCRGNet, Radio Galaxy Zoo and ConvXpress\n(novel classifier) are the architectures that best balance computational\nrequirements with recognition performance.", "positive": "Uncovering the geometry of the hot X-ray corona in the Seyfert galaxy\n NGC4151 with IXPE: We present an X-ray spectro-polarimetric analysis of the bright Seyfert\ngalaxy NGC4151. The source has been observed with the Imaging X-ray Polarimetry\nExplorer (IXPE) for 700 ks, complemented with simultaneous XMM-Newton (50 ks)\nand NuSTAR (100 ks) pointings. A polarization degree ${\\Pi} = 4.9 {\\pm} 1.1 \\%$\nand angle ${\\Psi}= 86{\\deg} {\\pm} 7{\\deg}$ east of north ($68\\%$ confidence\nlevel) are measured in the 2-8 keV energy range. The spectro-polarimetric\nanalysis shows that the polarization could be entirely due to reflection. Given\nthe low reflection flux in the IXPE band, this requires however a reflection\nwith a very large ($> 38 \\%$) polarization degree. Assuming more reasonable\nvalues, a polarization degree of the hot corona ranging from ${\\sim}4$ to\n${\\sim}8\\%$ is found. The observed polarization degree excludes a spherical\nlamppost geometry for the corona, suggesting instead a slab-like geometry,\npossibly a wedge, as determined via Monte Carlo simulations. This is further\nconfirmed by the X-ray polarization angle, which coincides with the direction\nof the extended radio emission in this source, supposed to match the disc axis.\nNGC4151 is the first AGN with an X-ray polarization measure for the corona,\nillustrating the capabilities of X-ray polarimetry and IXPE in unveiling its\ngeometry." }, { "anchor": "Dark Matter Trapping by Stellar Bars: The Shadow Bar: We investigate the complex interactions between the stellar disc and the\ndark-matter halo during bar formation and evolution using N-body simulations\nwith fine temporal resolution and optimally chosen spatial resolution. We find\nthat the forming stellar bar traps dark matter in the vicinity of the stellar\nbar into bar-supporting orbits. We call this feature the shadow bar. The shadow\nbar modifies both the location and magnitude of the angular momentum transfer\nbetween the disc and dark matter halo and adds 10 per cent to the mass of the\nstellar bar over 4 Gyr. The shadow bar is potentially observable by its density\nand velocity signature in spheroid stars and by direct dark matter detection\nexperiments. Numerical tests demonstrate that the shadow bar can diminish the\nrate of angular momentum transport from the bar to the dark matter halo by more\nthan a factor of three over the rate predicted by dynamical friction with an\nuntrapped dark halo, and thus provides a possible physical explanation for the\nobserved prevalence of fast bars in nature.", "positive": "Nuclear discs as clocks for the assembly history of early-type galaxies:\n the case of NGC4458: Approximately 20% of early-type galaxies host small nuclear stellar discs\nthat are tens to a few hundred parsecs in size. Such discs are expected to be\neasily disrupted during major galactic encounters, hence their age serve to\nconstrain their assembly history. We use VIMOS integral-field spectroscopic\nobservations for the intermediate-mass E0 galaxy NGC4458 and age-date its\nnuclear disc via high-resolution fitting of various model spectra. We find that\nthe nuclear disc is at least 6 Gyr old. A clue to gain narrow limits to the\nstellar age is our knowledge of the nuclear disc contribution to the central\nsurface brightness.\n The presence of an old nuclear disk, or the absence of disruptive encounters\nsince z~0.6, for a small galaxy such as NGC4458 which belongs to the Virgo\ncluster, may be consistent with a hierarchical picture for galaxy formation\nwhere the smallest galaxies assembles earlier and the crowded galactic\nenvironments reduce the incidence of galaxy mergers. On the other hand, NGC4458\ndisplays little or no bulk rotation except for a central kpc-scale\nkinematically-decoupled core. Slow rotation and decoupled core are usually\nexplained in terms of mergers. The presence and age of the nuclear disc\nconstraint these mergers to have happened at high redshift." }, { "anchor": "The early days of the Sculptor dwarf spheroidal galaxy: We present the high resolution spectroscopic study of five -3.9<=[Fe/H]<=-2.5\nstars in the Local Group dwarf spheroidal, Sculptor, thereby doubling the\nnumber of stars with comparable observations in this metallicity range. We\ncarry out a detailed analysis of the chemical abundances of alpha, iron peak,\nlight and heavy elements, and draw comparisons with the Milky Way halo and the\nultra faint dwarf stellar populations. We show that the bulk of the Sculptor\nmetal-poor stars follows the same trends in abundance ratios versus metallicity\nas the Milky Way stars. This suggests similar early conditions of star\nformation and a high degree of homogeneity of the interstellar medium. We find\nan outlier to this main regime, which seems to miss the products of the most\nmassive of the TypeII supernovae. In addition to its value to help refining\ngalaxy formation models, this star provides clues to the production of cobalt\nand zinc. Two of our sample stars have low odd-to-even barium isotope abundance\nratios, suggestive of a fair proportion of s-process; we discuss the\nimplication for the nucleosynthetic origin of the neutron capture elements.", "positive": "Nuclear Spirals in the inner Milky Way: We use hydrodynamical simulations to construct a new coherent picture for the\ngas flow in the Central Molecular Zone (CMZ), the region of our Galaxy within\n$R\\leq 500\\, \\mathrm{pc}$. We relate connected structures observed in $(l,b,v)$\ndata cubes of molecular tracers to nuclear spiral arms. These arise naturally\nin hydrodynamical simulations of barred galaxies, and are similar to those that\ncan be seen in external galaxies such as NGC4303 or NGC1097. We discuss a\nface-on view of the CMZ including the position of several prominent molecular\nclouds, such as Sgr B2, the $20\\,{\\rm km\\, s^{-1}}$ and $50\\,{\\rm km\\, s^{-1}}$\nclouds, the polar arc, Bania Clump 2 and Sgr C. Our model is also consistent\nwith the larger scale gas flow, up to $R\\simeq 3\\,\\rm kpc$, thus providing a\nconsistent picture of the entire Galactic bar region." }, { "anchor": "Infrared Galaxies in the Field of the Massive Cluster Abell S1063:\n Discovery of a Luminous Kiloparsec-Sized HII Region in a Gravitationally\n Lensed IR-Luminous Galaxy at $z=0.6$: Using the Spitzer Space Telescope and Herschel Space Observatory, we have\nconducted a survey of infrared galaxies in the field of the galaxy cluster\nAbell S1063 (AS1063) at $z=0.347$, which is one of the most massive clusters\nknown and a target of the HST CLASH and Frontier-Field surveys. The\nSpitzer/MIPS 24 $\\mu$m and Herschel/PACS & SPIRE images revealed that the core\nof AS1063 is surprisingly devoid of infrared sources, showing only a few\ndetectable sources within the central r$\\sim1^{\\prime}$. There is, however, one\nparticularly bright source (2.3 mJy at 24 $\\mu$m; 106 mJy at 160 $\\mu$m), which\ncorresponds to a background galaxy at $z=0.61$. The modest magnification factor\n(4.0$\\times$) implies that this galaxy is intrinsically IR-luminous (L$_{\\rm\nIR}=3.1\\times10^{11}\\ \\rm L_{\\odot}$). What is particularly interesting about\nthis galaxy is that HST optical/near-infrared images show a remarkably bright\nand large (1 kpc) clump at one edge of the disk. Our follow-up\noptical/near-infrared spectroscopy shows Balmer (H$\\alpha$-H8) and forbidden\nemission from this clump ([OII] $\\lambda$3727, [OIII]\n$\\lambda\\lambda$4959,5007, [NII] $\\lambda\\lambda$6548,6583), indicating that it\nis a HII region. The HII region appears to have formed in-situ, as\nkinematically it is part of a rotating disk, and there is no evidence of nearby\ninteracting galaxies. With an extinction correction of A$_{\\rm V}=1.5$ mag, the\nstar formation rate of this giant HII region is $\\sim$10 M$_{\\odot}$ yr$^{-1}$,\nwhich is exceptionally large, even for high redshift HII regions. Such a large\nand luminous HII region is often seen at $z\\sim2$ but quite rare in the nearby\nUniverse.", "positive": "Constraining AGN triggering mechanisms through the clustering analysis\n of active black holes: The triggering mechanisms for Active Galactic Nuclei (AGN) are still debated.\nSome of the most popular ones include galaxy interactions (IT) and disk\ninstabilities (DI). Using an advanced semi analytic model (SAM) of galaxy\nformation, coupled to accurate halo occupation distribution modeling, we\ninvestigate the imprint left by each separate triggering process on the\nclustering strength of AGN at small and large scales. Our main results are as\nfollows: i) DIs, irrespective of their exact implementation in the SAM, tend to\nfall short in triggering AGN activity in galaxies at the center of halos with\n$M_h>10^{13.5} h^{-1}M_{\\odot}$. On the contrary, the IT scenario predicts\nabundance of active, central galaxies that generally agrees well with\nobservations at every halo mass. ii) The relative number of satellite AGN in\nDIs at intermediate-to-low luminosities is always significantly higher than in\nIT models, especially in groups and clusters. The low AGN satellite fraction\npredicted for the IT scenario might suggest that different feeding modes could\nsimultaneously contribute to the triggering of satellite AGN. iii) Both\nscenarios are quite degenerate in matching large-scale clustering measurements,\nsuggesting that the sole average bias might not be an effective observational\nconstraint. iv) Our analysis suggests the presence of both a mild luminosity\nand a more consistent redshift dependence in the AGN clustering, with AGN\ninhabiting progressively less massive dark matter halos as the redshift\nincreases. We also discuss the impact of different observational selection cuts\nin measuring AGN clustering, including possible discrepancies between optical\nand X-ray surveys." }, { "anchor": "The Mopra Southern Galactic Plane CO Survey - Data Release 1: We present observations of the first ten degrees of longitude in the Mopra\ncarbon monoxide (CO) survey of the southern Galactic plane (Burton et al.\n2013), covering Galactic longitude l = 320-330{\\deg} and latitude b =\n$\\pm$0.5{\\deg}, and l = 327-330{\\deg}, b = +0.5-1.0{\\deg}. These data have been\ntaken at 35 arc sec spatial resolution and 0.1 km/s spectral resolution,\nproviding an unprecedented view of the molecular clouds and gas of the southern\nGalactic plane in the 109-115 GHz J = 1-0 transitions of 12CO, 13CO, C18O and\nC17O. Together with information about the noise statistics from the Mopra\ntelescope, these data can be retrieved from the Mopra CO website and the\nCSIRO-ATNF data archive.", "positive": "Narrow absorption lines with two observations of Sloan Digital Sky\n Survey: We assemble 3524 quasars from Sloan Digital Sky Survey (SDSS) with repeated\nobservations to search for variations of narrow C IV1548,1551 and Mg\nII2796,2803 absorption doublets in spectral regions shortward of 7000 Ang at\nthe observed frame, which corresponds to time-scales of about 150 ~ 2643 days\nat quasar rest frame. In these quasar spectra, we detect 3580 C IV absorption\nsystems with z_{abs} = 1.5188 ~ 3.5212, and 1809 Mg II absorption systems with\nz_{abs} = 0.3948 ~ 1.7167. In term of the absorber velocity (beta) distribution\nat quasar rest frame, we find a substantial number of C IV absorbers with\nbeta<0.06, which might be connected to the absorptions of quasar outflows. The\noutflow absorptions peak at v~2000 km/s and drop rapidly below the peak value.\nAmong 3580 C IV absorption systems, 52 systems (~ 1.5%) show obvious variations\nin equivalent widths at the absorber rest frame (Wr): 16 enhanced, 16 emerged,\n12 weaken, and 8 disappeared systems, respectively. We find that changes in\nWr548 are neither related to time-scales of the two SDSS observations, nor to\nabsorber velocities at the quasar rest frame. Variable absorptions in\nlow-ionization species are important to constraint the physical conditions of\nabsorbing gas. There are two variable Mg II absorption systems measured from\nSDSS spectra detected by Hacker et al. However, in our Mg II$ absorption\nsample, we find that neither shows variable absorption with confident levels of\n>4sigma for lambda2796 lines and >3sigma for lambda2803 lines." }, { "anchor": "COOL-LAMPS. VII. Quantifying Strong-lens Scaling Relations with 177\n Cluster-scale Gravitational Lenses in DECaLS: We compute parametric measurements of the Einstein-radius-enclosed total mass\nfor 177 cluster-scale strong gravitational lenses identified by the ChicagO\nOptically-selected Lenses Located At the Margins of Public Surveys (COOL-LAMPS)\ncollaboration with lens redshifts ranging from $0.2 \\lessapprox z \\lessapprox\n1.0$ using only two measured parameters in each lensing system: the Einstein\nradius, and the brightest-cluster-galaxy (BCG) redshift. We then constrain the\nEinstein-radius-enclosed luminosity and stellar mass by fitting parametric\nspectral energy distributions (SEDs) with aperture photometry from the Dark\nEnergy Camera Legacy Survey (DECaLS) in the $g$, $r$, and $z$-band Dark Energy\nCamera (DECam) filters. We find that the BCG redshift, enclosed total mass, and\nenclosed luminosity are strongly correlated and well described by a planar\nrelationship in 3D space. We also find that the enclosed total mass and stellar\nmass are correlated with a logarithmic slope of $0.443\\pm0.035$, and the\nenclosed total mass and stellar-to-total mass fraction are correlated with a\nlogarithmic slope of $-0.563\\pm0.035$. The correlations described here can be\nused to validate strong lensing candidates in upcoming imaging surveys -- such\nas Rubin/Legacy Survey of Space and Time (LSST) -- in which an algorithmic\ntreatment of lensing systems will be needed due to the sheer volume of data\nthese surveys will produce.", "positive": "The Sixteenth Data Release of the Sloan Digital Sky Surveys: First\n Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra: This paper documents the sixteenth data release (DR16) from the Sloan Digital\nSky Surveys; the fourth and penultimate from the fourth phase (SDSS-IV). This\nis the first release of data from the southern hemisphere survey of the Apache\nPoint Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from\nAPOGEE-2 North are also included. DR16 is also notable as the final data\nrelease for the main cosmological program of the Extended Baryon Oscillation\nSpectroscopic Survey (eBOSS), and all raw and reduced spectra from that project\nare released here. DR16 also includes all the data from the Time Domain\nSpectroscopic Survey (TDSS) and new data from the SPectroscopic IDentification\nof ERosita Survey (SPIDERS) programs, both of which were co-observed on eBOSS\nplates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point\nObservatory (MaNGA) survey (or the MaNGA Stellar Library \"MaStar\"). We also\npreview future SDSS-V operations (due to start in 2020), and summarize plans\nfor the final SDSS-IV data release (DR17)." }, { "anchor": "Morphology Dependence Of Stellar Age in Quenched Galaxies at Redshift ~\n 1.2: Massive Compact Galaxies Are Older Than More Extended Ones: We report the detection of morphology dependent stellar age in massive\nquenched galaxies (QGs) at z~1.2. The sense of the dependence is that compact\nQGs are 0.5-2 Gyr older than normal-sized ones. The evidence comes from three\ndifferent age indicators, Dn4000, Hdelta and fits to spectral synthesis models,\napplied to their stacked optical spectra. All age indicators consistently show\nthat the stellar populations of compact QGs are older than their normally-sized\ncounterparts. We detect weak [OII] emission in a fraction of QGs, and the\nstrength of the line, when present, is similar between the two samples;\nhowever, compact galaxies exhibit significantly lower frequency of [OII]\nemission than normal ones. A fraction of both samples are individually detected\nin 7 Ms Chandra X-ray images (luminosities$\\sim10^{40}$-$10^{41}$ erg/sec). 7\nMs stacks of non-detected galaxies show similarly low luminosities in the soft\nband only, consistent with a hot gas origin for the X-ray emission. While both\n[OII] emitters and non-emitters are also X-ray sources among normal galaxies,\nno compact galaxy with [OII] emission is an X-ray source, arguing against an\nAGN powering the line in compact galaxies. We interpret the [OII] properties as\nfurther evidence that compact galaxies are older and further along into the\nprocess of quenching star-formation and suppressing gas accretion. Finally, we\nargue that the older age of compact QGs is evidence of progenitor bias: compact\nQGs simply reflect the smaller sizes of galaxies at their earlier quenching\nepoch, with stellar density most likely having nothing directly to do with\ncessation of star-formation.", "positive": "The Black Hole Mass and the Stellar Ring in NGC 3706: We determine the mass of the nuclear black hole ($M$) in NGC 3706, an early\ntype galaxy with a central surface brightness minimum arising from an apparent\nstellar ring, which is misaligned with respect to the galaxy's major axis at\nlarger radii. We fit new HST/STIS and archival data with axisymmetric orbit\nmodels to determine $M$, mass-to-light ratio ($\\Upsilon_V$), and dark matter\nhalo profile. The best-fit model parameters with 1$\\sigma$ uncertainties are $M\n= (6.0^{+0.7}_{-0.9}) \\times 10^8\\ M_{\\scriptscriptstyle \\odot}$ and\n$\\Upsilon_V = 6.0 \\pm 0.2\\ M_{\\scriptscriptstyle \\odot}\\ L_{{\\scriptscriptstyle\n\\odot},V}^{-1}$ at an assumed distance of 46 Mpc. The models are inconsistent\nwith no black hole at a significance of $\\Delta\\chi^2 = 15.4$ and require a\ndark matter halo to adequately fit the kinematic data, but the fits are\nconsistent with a large range of plausible dark matter halo parameters. The\nring is inconsistent with a population of co-rotating stars on circular orbits,\nwhich would produce a narrow line-of-sight velocity distribution (LOSVD).\nInstead, the ring's LOSVD has a small value of $|V|/\\sigma$, the ratio of mean\nvelocity to velocity dispersion. Based on the observed low $|V|/\\sigma$, our\norbit modeling, and a kinematic decomposition of the ring from the bulge, we\nconclude that the stellar ring contains stars that orbit in both directions. We\nconsider potential origins for this unique feature, including multiple tidal\ndisruptions of stellar clusters, a change in the gravitational potential from\ntriaxial to axisymmetric, resonant capture and inclining of orbits by a binary\nblack hole, and multiple mergers leading to gas being funneled to the center of\nthe galaxy." }, { "anchor": "Multi-frequency study of large size radio galaxies 3C 35 and 3C 284: We report multi-frequency observations of large radio galaxies 3C 35 and 3C\n284. The low-frequency observations were done with Giant Metrewave Radio\nTelescope starting from $\\sim150$ MHz, and the high-frequency observations were\ndone with the Very Large Array. We have studied the radio morphology of these\ntwo sources at different frequencies. We present the spectral ageing map using\ntwo of the most widely used models, the Kardashev-Pacholczyk and Jaffe-Perola\nmodels. Another more realistic and complex Tribble model is also used. We also\ncalculate the jet-power and the speed of the radio lobes of these galaxies. We\ncheck whether any episodic jet activity is present in these galaxies and found\nno sign of such activity.", "positive": "Stellar Population Properties of ETGs in Compact Groups of Galaxies: We present results on the study of the stellar population in Early-Type\ngalaxies (ETGs) belonging to 151 Compact Groups (CGs). We also selected a field\nsample composed of 846 ETGs to investigate environmental effects on galaxy\nevolution. We find that the dependences of mean stellar ages, [Z/H] and\n[$\\alpha$/Fe] on central stellar velocity dispersion are similar, regardless\nwhere the ETG resides, CGs or field. When compared to the sample of centrals\nand satellites from the literature, we find that ETGs in GCs behave similarly\nto centrals, especially those embedded in low-mass haloes ($M_{h} < 10^\n{12.5}M_{\\odot}$). Except for the low-mass limit, where field galaxies present\na Starforming signature, not seen in CGs, the ionization agent of the gas in CG\nand field galaxies seem to be similar and due to hot, evolved low-mass stars.\nHowever, field ETGs present an excess of H$\\alpha$ emission relative to ETGs in\nCGs. Additionally, we performed a dynamical analysis, which shows that CGs\npresent a bimodality in the group velocity dispersion distribution - a high and\nlow-$\\sigma$ mode. Our results indicate that high-$\\sigma$ groups have a\nsmaller fraction of spirals, shorter crossing times, and a more luminous\npopulation of galaxies than the low $\\sigma$ groups. It is important to\nemphasize that our findings point to a small environmental impact on galaxies\nlocated in CGs. The only evidence we find is the change in gas content,\nsuggesting environmentally-driven gas loss." }, { "anchor": "Testing PDR models against ISO fine structure line data for\n extragalactic sources: Far-infrared [C ii] 158 micron, [O i] 145 micron and [O i] 63 micron fine\nstructure emission line fluxes were measured from archival Infrared Space\nObservatory Long Wavelength Spectrometer spectra of 46 extragalactic sources,\nwith 28 sources providing detections in all three lines. For 12 of the sources,\nthe contribution to the [C ii] 158 micron line flux from H ii regions could be\nestimated from their detected [N ii] 122 micron line fluxes. The measured [C\nii]/[O i] and [O i] 63/145 micron line flux ratios were compared with those\nfrom a grid of PDR models previously computed using the UCL PDR code.\nPersistent offsets between the observed and modelled line ratios could be\npartly attributed to the effects of [O i] 63 micron self-absorption. Using the\nSMMOL code, we calculated model [O i] line profiles and found that the strength\nof the [O i] 63 micron line was reduced by 20-80%, depending on the PDR\nparameters. We conclude that high PDR densities and radiation field strengths,\ncoupled with the effects of [O i] 63 micron self-absorption, are likely to\nprovide the best match to the observed line flux ratios.", "positive": "New Local Volume Dwarf Galaxy Candidates from the DESI Legacy Imaging\n Surveys: We undertook a search for new dwarf galaxies in the vicinity of relatively\nisolated nearby galaxies with distances $D < 12$ Mpc and stellar masses in the\n$2\\times10^{11}-3\\times10^8~M_{\\odot}$ interval, using the data from the DESI\nLegacy Imaging Surveys. Around the 46 considered Local Volume galaxies, $67$\nnew candidates for satellites of these galaxies were found. About half of them\nare classified as spheroidal dwarfs of low surface brightness. The new galaxies\nare included in the Local Volume database (LVGDB), which now contains 1421\nobjects, being 63% more than the Updated Nearby Galaxy Catalog." }, { "anchor": "The Sami Galaxy Survey: stellar populations of passive spiral galaxies\n in different environment: We investigate the stellar populations of passive spiral galaxies as a\nfunction of mass and environment, using integral field spectroscopy data from\nthe Sydney-AAO Multi-object Integral field spectrograph Galaxy Survey. Our\nsample consists of $52$ cluster passive spirals and $18$ group/field passive\nspirals, as well as a set of S0s used as a control sample. The age and [Z/H]\nestimated by measuring Lick absorption line strength indices both at the center\nand within $1R_{\\rm e}$ do not show a significant difference between the\ncluster and the field/group passive spirals. However, the field/group passive\nspirals with log(M$_\\star$/M$_\\odot)\\gtrsim10.5$ show decreasing [$\\alpha$/Fe]\nalong with stellar mass, which is $\\sim0.1$ dex smaller than that of the\ncluster passive spirals. We also compare the stellar populations of passive\nspirals with S0s. In the clusters, we find that passive spirals show slightly\nyounger age and lower [$\\alpha$/Fe] than the S0s over the whole mass range. In\nthe field/group, stellar populations show a similar trend between passive\nspirals and S0s. In particular, [$\\alpha$/Fe] of the field/group S0s tend to be\nflattening with increasing mass above log(M$_\\star$/M$_\\odot)\\gtrsim10.5$,\nsimilar to the field/group passive spirals. We relate the age and [$\\alpha$/Fe]\nof passive spirals to their mean infall time in phase-space; we find a positive\ncorrelation, in agreement with the prediction of numerical simulations. We\ndiscuss the environmental processes that can explain the observed trends. The\nresults lead us to conclude that the formation of the passive spirals and their\ntransformation into S0s may significantly depend on their environments.", "positive": "The Dawes Review 8: Measuring the Stellar Initial Mass Function: The birth of stars and the formation of galaxies are cornerstones of modern\nastrophysics. While much is known about how galaxies globally and their stars\nindividually form and evolve, one fundamental property that affects both\nremains elusive. This is problematic because this key property, the birth mass\ndistribution of stars, referred to as the stellar initial mass function (IMF),\nis a key tracer of the physics of star formation that underpins almost all of\nthe unknowns in galaxy and stellar evolution. It is perhaps the greatest source\nof systematic uncertainty in star and galaxy evolution. The past decade has\nseen a growing number and variety of methods for measuring or inferring the\nshape of the IMF, along with progressively more detailed simulations,\nparalleled by refinements in the way the concept of the IMF is applied or\nconceptualised on different physical scales. This range of approaches and\nevolving definitions of the quantity being measured has in turn led to\nconflicting conclusions regarding whether or not the IMF is universal. Here I\nreview and compare the growing wealth of approaches to our understanding of\nthis fundamental property that defines so much of astrophysics. I summarise the\nobservational measurements from stellar analyses, extragalactic studies and\ncosmic constraints, and highlight the importance of considering potential IMF\nvariations, reinforcing the need for measurements to quantify their scope and\nuncertainties carefully, in order for this field to progress. I present a new\nframework to aid the discussion of the IMF and promote clarity in the further\ndevelopment of this fundamental field." }, { "anchor": "A Survey Length for AGN Variability Studies: The damped random walk (DRW) process is one of the most commonly used and\nsimplest stochastic models to describe variability of active galactic nuclei\n(AGN). An AGN light curve can be converted to just two DRW model parameters -\nthe signal decorrelation timescale $\\tau$ and the asymptotic amplitude\n${SF}_{\\infty}$. By simulation means, we have recently shown that in order to\nmeasure the decorrelation timescale accurately, the experiment or the light\ncurve length must be at least 10 times the underlying decorrelation timescale.\nIn this paper, we investigate the origin of this requirement and find that\ntypical AGN light curves do not sufficiently represent the intrinsic stationary\nprocess. We simulated extremely long (10,000$\\tau$) AGN light curves using DRW,\nand then measured the variance and the mean of short light curves spanning\n1-1000$\\tau$. We modeled these light curves with DRW to obtain both the signal\ndecorrelation timescale $\\tau$ and the asymptotic amplitude ${SF}_{\\infty}$.\nThe variance in light curves shorter than $\\approx30\\tau$ is smaller than that\nof the input process, as estimated by both a simple calculation from the light\ncurve and by DRW modeling. This means that while the simulated stochastic\nprocess is intrinsically stationary, short light curves do not adequately\nrepresent the stationary process. Since the variance and timescale are\ncorrelated, underestimated variances in short light curves lead to\nunderestimated timescales as compared to the input process. It seems, that a\nsimulated AGN light curve does not fully represent the underlying DRW process\nuntil its length reaches even $\\approx30$ decorrelation timescales. Modeling\nshort AGN light curves with DRW leads to biases in measured parameters of the\nmodel - the amplitude being too small and the timescale being too short.", "positive": "The Link Between Light and Mass in Late-type Spiral Galaxy Disks: We present the correlation between the extrapolated central disk surface\nbrightness (mu) and extrapolated central surface mass density (Sigma) for\ngalaxies in the DiskMass sample. This mu-Sigma-relation has a small scatter of\n30% at the high-surface-brightness (HSB) end. At the low surface brightness\n(LSB) end, galaxies fall above the mu-Sigma-relation, which we attribute to\ntheir higher dark matter content. After correcting for the dark matter, as well\nas for the contribution of gas and the effects of radial gradients in the disk,\nthe LSB end falls back on the linear mu-Sigma-relation. The resulting scatter\nabout the corrected mu-Sigma-relation is 25% at the HSB end, and about 50% at\nthe LSB end. The intrinsic scatter in the mu-Sigma-relation is estimated to be\n10% to 20%. Thus, if the surface brightness is known, the stellar surface mass\ndensity is known to within 10-20% (random error). Assuming disks have an\nexponential vertical distribution of mass, the average (M_L)_K is 0.24\nMsun/Lsun, with an intrinsic scatter around the mean of at most 0.05 Msun/Lsun.\nThis value for (M/L)_K is 20% smaller than we found in Martinsson et al.,\nmainly due to the correction for dark matter applied here. This small scatter\nmeans that among the galaxies in our sample variations in scale height,\nvertical density profile shape, and/or the ratio of vertical over radial\nvelocity dispersion must be small." }, { "anchor": "Time stamps of vertical phase mixing in the Galactic disk from\n LAMOST-Gaia stars: The perturbation mechanism of the Galactic disk has puzzled us for a long\ntime. The imprints from perturbations provide important diagnostics on the disk\nformation and evolution. Here we try to constrain when the vertical\nperturbation took place in the disk by tracking the phase mixing history.\nFirstly, we clearly depict the spiral structures of radial ($v_R$) and\nazimuthal ($v_{\\phi}$) velocities in the phase space of the vertical position\nand velocity ($z$-$v_z$) with 723,871 LAMOST-Gaia combined stars. Then, we\ninvestigate the variation of the spirals with stellar age ($\\tau$) by dividing\nthe sample into seven stellar age bins. Finally, we find that the spirals\nexplicitly exist in all the bins, even in the bin of $\\tau<0.5$\\,Gyr, except\nfor the bin of $\\tau>6.0$\\,Gyr. This constrains the vertical perturbation\nprobably starting no later than 0.5\\,Gyr ago. But we can not rule out whether\nthe young stars ($\\tau<0.5$\\,Gyr) inherit the oscillations from the perturbed\nISM where they born from. This study provides some important observational\nevidences to understand the disk perturbation mechanisms, even the formation\nand evolution of our Galaxy.", "positive": "Studying the effects and cause of the massive star formation in Messier\n 8 East: Messier 8 (M8), one of the brightest HII regions in our Galaxy, is associated\nwith two prominent massive star-forming regions: M8-Main, the particularly\nbright part of the large scale HII region (mainly) ionised by the stellar\nsystem Herschel 36 (Her 36) and M8 East (M8 E), which is mainly powered by a\ndeeply embedded young stellar object (YSO), a bright infrared (IR) source,\nM8E-IR. We aim to study the interaction of the massive star-forming region M8 E\nwith its surroundings and to compare the star-forming environments of M8-Main\nand M8 E. We used the IRAM 30 m telescope to perform an imaging spectroscopy\nsurvey of the molecular environment of M8E-IR. We imaged and analysed data for\nthe $J$ = 1 $\\to$ 0 rotational transitions of $^{12}$CO, $^{13}$CO, N$_2$H$^+$,\nHCN, H$^{13}$CN, HCO$^+$, H$^{13}$CO$^+$, HNC and HN$^{13}$C observed for the\nfirst time toward M8~E. We used LTE and non-LTE techniques to determine column\ndensities of the observed species and to constrain the physical conditions of\nthe gas responsible for their emission. Examining the YSO population in M8~E\nallows us to explore the observed ionization front (IF) as seen in GLIMPSE\n8~$\\mu$m emission image. We find that $^{12}$CO probes the warm diffuse gas\nalso traced by the GLIMPSE 8~$\\mu$m emission, while N$_2$H$^+$ and HN$^{13}$C\ntrace the cool and dense gas. We find that the star-formation in M8~E appears\nto be triggered by the earlier formed stellar cluster NGC~6530, which powers an\nHII region giving rise to an IF that is moving at a speed $\\geq$\n0.26~km~s$^{-1}$ across M8~E. We derive temperatures of 80 K and 30 K for the\nwarm and cool gas components, respectively, and constrain H$_2$ volume\ndensities to be in the range of 10$^4$--10$^6$~cm$^{-3}$. Comparison of the\nobserved abundances of various species reflects the fact that M8~E is at an\nearlier stage of massive star formation than M8-Main." }, { "anchor": "Parameters of Three Selected Model Galactic Potentials Based on the\n Velocities of Objects at Distances up to 200 kpc: This paper is a continuation of our recent paper devoted to refining the\nparameters of three component (bulge, disk, halo) axisymmetric model Galactic\ngravitational potentials differing by the expression for the dark matter halo\nusing the velocities of distant objects. In all models the bulge and disk\npotentials are described by the Miyamoto-Nagai expressions. In our previous\npaper we used the Allen-Santill'an (I), Wilkinson--Evans (II), and\nNavarro-Frenk-White (III) models to describe the halo. In this paper we use a\nspherical logarithmic Binney potential (model IV), a Plummer sphere (model V),\nand a Hernquist potential (model VI) to describe the halo. A set of present-day\nobservational data in the range of Galactocentric distances R from 0 to 200 kpc\nis used to refine the parameters of the listed models, which are employed most\ncommonly at present. The model rotation curves are fitted to the observed\nvelocities by taking into account the constraints on the local matter density\nand the vertical force . Model VI looks best among the three models considered\nhere from the viewpoint of the achieved accuracy of fitting the model rotation\ncurves to the measurements. This model is close to the Navarro-Frenk-White\nmodel III refined and considered best in our previous paper, which is shown\nusing the integration of the orbits of two globular clusters, Lynga 7 and NGC\n5053, as an example.", "positive": "Integrated parameters of star clusters: A comparison of theory and\n observations: (Abridged) This paper presents integrated magnitude and colours for synthetic\nclusters. The integrated parameters have been obtained for the whole cluster\npopulation as well as for the main-sequence (MS) population of star clusters.\nWe have also estimated observed integrated magnitudes and colours of MS\npopulation of galactic open clusters, LMC and SMC star clusters. It is found\nthat the colour evolution of MS population of star clusters is not affected by\nthe stochastic fluctuations, however these fluctuations significantly affect\nthe colour evolution of the whole cluster population. The fluctuations are\nmaximum in $(V-I)$ colour in the age range 6.7 $<$ log (age) $<$ 7.5. Evolution\nof integrated colours of MS population of the clusters in the Milky Way, LMC\nand SMC, obtained in the present study are well explained by the present\nsynthetic cluster model. The observed integrated $(B-V)$ colours of MS\npopulation of LMC star clusters having age $\\geq$ 500 Myr seem to be\ndistributed around $Z=$ 0.004 model, whereas $(V-I)$ colours are found to be\nmore bluer than those predicted by the $Z=$ 0.004 model. $(V-I)$ vs $(B-V)$\ntwo-colour diagram for the MS population of the Milky Way star clusters shows a\nfair agreement between the observations and present model, however the diagrams\nfor LMC and SMC clusters indicate that observed $(V-I)$ colours are relatively\nbluer. Possible reasons for this anomaly have been discussed." }, { "anchor": "Migration in the shearing sheet and estimates for young open cluster\n migration: Using tracer particles embedded in self-gravitating shearing sheet N-body\nsimulations, we investigate the distance in guiding centre radius that stars or\nstar clusters can migrate in a few orbital periods. The standard deviations of\nguiding centre distributions and maximum migration distances depend on the\nToomre or critical wavelength and the contrast in mass surface density caused\nby spiral structure. Comparison between our simulations and estimated guiding\nradii for a few young super-solar metallicity open clusters, including NGC\n6583, suggests that the contrast in mass surface density in the solar\nneighbourhood has standard deviation (in the surface density distribution)\ndivided by mean of about 1/4 and larger than measured using COBE data by\nDrimmel and Spergel. Our estimate is consistent with a standard deviation of\n$\\sim$0.07 dex in the metallicities measured from high-quality spectroscopic\ndata for 38 young open clusters (<1 Gyr) with mean galactocentric radius 7-9\nkpc.", "positive": "The SSA22 HI Tomography Survey (SSA22-HIT). I. Data Set and Compiled\n Redshift Catalog: We conducted a deep spectroscopic survey, named SSA22-HIT, in the SSA22 field\nwith the DEep Imaging MultiObject Spectrograph (DEIMOS) on the Keck telescope,\ndesigned to tomographically map high-z HI gas through analysis of Lya\nabsorption in background galaxies' spectra. In total, 198 galaxies were\nspectroscopically confirmed at 2.5 < z < 6 with a few low-z exceptions in the\n26 x 15 arcmin^2 area, of which 148 were newly determined in this study. Our\nredshift measurements were merged with previously confirmed redshifts available\nin the 34 x 27 arcmin^2 area of the SSA22 field. This compiled catalog\ncontaining 730 galaxies of various types at z > 2 is useful for various\napplications, and it is made publicly available. Our SSA22-HIT survey has\nincreased by approximately twice the number of spectroscopic redshifts of\nsources at z > 3.2 in the observed field. From a comparison with publicly\navailable redshift catalogs, we show that our compiled redshift catalog in the\nSSA22 field is comparable to those among major extragalactic survey fields in\nterms of a combination of wide area and high surface number density of objects\nat z > 2. About 40 % of the spectroscopically confirmed objects in SSA22-HIT\nshow reasonable quality of spectra in the wavelengths shorter than Lya when a\nsufficient amount of smoothing is adopted. Our data set enables us to make the\nHI tomographic map at z > 3, which we present in a parallel study." }, { "anchor": "Direct N-body simulations of globular clusters: (I) Palomar 14: We present the first ever direct $N$-body computations of an old Milky Way\nglobular cluster over its entire life time on a star-by-star basis. Using\nrecent GPU hardware at Bonn University, we have performed a comprehensive set\nof $N$-body calculations to model the distant outer halo globular cluster\nPalomar 14 (Pal 14). By varying the initial conditions we aim at finding an\ninitial $N$-body model which reproduces the observational data best in terms of\nits basic parameters, i.e. half-light radius, mass and velocity dispersion. We\nfurthermore focus on reproducing the stellar mass function slope of Pal 14\nwhich was found to be significantly shallower than in most globular clusters.\nWhile some of our models can reproduce Pal 14's basic parameters reasonably\nwell, we find that dynamical mass segregation alone cannot explain the mass\nfunction slope of Pal 14 when starting from the canonical Kroupa initial mass\nfunction (IMF). In order to seek for an explanation for this discrepancy, we\ncompute additional initial models with varying degrees of primordial mass\nsegregation as well as with a flattened IMF. The necessary degree of primordial\nmass segregation turns out to be very high. This modelling has shown that the\ninitial conditions of Pal 14 after gas expulsion must have been a half-mass\nradius of about 20 pc, a mass of about 50000 M$_{\\odot}$, and possibly some\nmass segregation or an already established non-canonical IMF depleted in\nlow-mass stars. Such conditions might be obtained by a violent early\ngas-expulsion phase from an embedded cluster born with mass segregation. Only\nat large Galactocentric radii are clusters likely to survive as bound entities\nthe destructive gas-expulsion process we seem to have uncovered for Pal 14. In\naddition we compute a model with a 5% primordial binary fraction to test if\nsuch a population has an effect on the cluster's evolution.", "positive": "On the radial metallicity gradient and radial migration effect of the\n Galactic disk: We study the radial metallicity gradient $\\Delta[M/H]/\\Delta R_g$ as a\nfunction of [Mg/Fe] and $|Z|$ with the help of a guiding radius based on the\nApache Point Observatory Galactic Evolution Experiment and Gaia and then\nanalyze the radial migration effect on the radial metallicity gradient and\nmetallicity-rotation gradient between the Galactic thin and thick disks. The\nderived trend of gradient $\\Delta[M/H]/\\Delta R_g$ versus [Mg/Fe] shows a\ntransition at [Mg/Fe] $\\sim 0.18$ dex, below which the gradient is negative and\nvaries a little as [Mg/Fe] increases; however, it changes sharply in [Mg/Fe]\nranges of 0.16-0.18, above which the gradient increases linearly with\nincreasing [Mg/Fe], being a positive value at [Mg/Fe]$\\gtrsim 0.22$ dex. These\npositive gradients in the high-[Mg/Fe] populations are found at $|Z| < 0.8$\nkpc, and there are nearly no gradients toward higher $|Z|$. By comparing the\nmetallicity distributions, the radial metallicity gradients $\\Delta[M/H]/\\Delta\nR$ and the metallicity-rotation gradients between the total sample and\n$|R-R_g|<2$ kpc subsample (or $|R-R_g|>2$ kpc subsample), we find that, for the\nthick disk, blurring flattens the gradient $\\Delta[M/H]/\\Delta R$ and favors\nmetal-poor high-eccentricity stars. These stars are responsible for the\nmeasured positive metallicity-rotation gradient of the thick disk." }, { "anchor": "Stellar dynamics and tidal disruption events in galactic nuclei: The disruption of a star by the tidal field of a massive black hole is the\nfinal outcome of a chain of complex dynamical processes in the host galaxy. I\nintroduce the \"loss cone problem\", and describe the many theoretical and\nnumerical challenges on the path of solving it. I review various dynamical\nchannels by which stars can be supplied to a massive black hole, and the\nrelevant dynamical relaxation / randomization mechanisms. I briefly mention\nsome \"exotic\" tidal disruption scenarios, and conclude by discussing some new\ndynamical results that are changing our understanding of dynamics near a\nmassive black hole, and may well be relevant for tidal disruption dynamics.", "positive": "The ALFALFA \"Almost Darks\" Campaign: Pilot VLA HI Observations of Five\n High Mass-to-Light Ratio Systems: We present VLA HI spectral line imaging of 5 sources discovered by ALFALFA.\nThese targets are drawn from a larger sample of systems that were not uniquely\nidentified with optical counterparts during ALFALFA processing, and as such\nhave unusually high HI mass to light ratios. These candidate \"Almost Dark\"\nobjects fall into 4 categories: 1) objects with nearby HI neighbors that are\nlikely of tidal origin; 2) objects that appear to be part of a system of\nmultiple HI sources, but which may not be tidal in origin; 3) objects isolated\nfrom nearby ALFALFA HI detections, but located near a gas-poor early-type\ngalaxy; 4) apparently isolated sources, with no object of coincident redshift\nwithin ~400 kpc. Roughly 75% of the 200 objects without identified counterparts\nin the $\\alpha$.40 database (Haynes et al. 2011) fall into category 1. This\npilot sample contains the first five sources observed as part of a larger\neffort to characterize HI sources with no readily identifiable optical\ncounterpart at single dish resolution. These objects span a range of HI mass\n[7.41 < log(M$_{\\rm HI}$) < 9.51] and HI mass to B-band luminosity ratios (3 <\nM$_{\\rm HI}$/L$_{\\rm B}$ < 9). We compare the HI total intensity and velocity\nfields to SDSS optical imaging and to archival GALEX UV imaging. Four of the\nsources with uncertain or no optical counterpart in the ALFALFA data are\nidentified with low surface brightness optical counterparts in SDSS imaging\nwhen compared with VLA HI intensity maps, and appear to be galaxies with clear\nsigns of ordered rotation. One source (AGC 208602) is likely tidal in nature.\nWe find no \"dark galaxies\" in this limited sample. The present observations\nreveal complex sources with suppressed star formation, highlighting both the\nobservational difficulties and the necessity of synthesis follow-up\nobservations to understand these extreme objects. (abridged)" }, { "anchor": "Characterizing filaments in regions of high-mass star formation:\n High-resolution submilimeter imaging of the massive star-forming complex NGC\n 6334 with ArT\u00e9MiS: Herschel observations of nearby molecular clouds suggest that interstellar\nfilaments and prestellar cores represent two fundamental steps in the star\nformation process. The observations support a picture of low-mass star\nformation according to which ~ 0.1 pc-wide filaments form first in the cold\ninterstellar medium, probably as a result of large-scale compression of\ninterstellar matter by supersonic turbulent flows, and then prestellar cores\narise from gravitational fragmentation of the densest filaments. Whether this\nscenario also applies to regions of high-mass star formation is an open\nquestion, in part because Herschel data cannot resolve the inner width of\nfilaments in the nearest regions of massive star formation.\n We used the bolometer camera ArTeMiS on the APEX telescope to map the central\npart of the NGC6334 complex at a factor of > 3 higher resolution than Herschel\nat 350 microns. Combining ArTeMiS data with Herschel data allowed us to study\nthe structure of the main filament of the complex with a resolution of 8\" or <\n0.07 pc at d ~ 1.7 kpc.\n Our study confirms that this filament is a very dense, massive linear\nstructure with a line mass ranging from ~ 500 Msun/pc to ~ 2000 Msun/pc over\nnearly 10 pc. It also demonstrates that its inner width remains as narrow as W\n~ 0.15 +- 0.05 pc all along the filament length, within a factor of < 2 of the\ncharacteristic 0.1 pc value found with Herschel for lower-mass filaments in the\nGould Belt. While it is not completely clear whether the NGC 6334 filament will\nform massive stars or not in the future, it is two to three orders of magnitude\ndenser than the majority of filaments observed in Gould Belt clouds, and yet\nhas a very similar inner width. This points to a common physical mechanism for\nsetting the filament width and suggests that some important structural\nproperties of nearby clouds also hold in high-mass star forming regions.", "positive": "Barred S0 Galaxies in the Coma Cluster: This study uses r-band images from the Eighth Data Release of the Sloan\nDigital Sky Survey (SDSS DR8) to study bars in lenticular (S0) galaxies in one\nof the nearest rich cluster environments, the Coma cluster. We develop\ntechniques for bar detection, and assess their success when applied to SDSS\nimage data. To detect and characterise bars we perform 2D bulge+disk+bar light\ndecompositions of galaxy images with GALFIT. Using a sample of artificial\ngalaxy images we determine the faintest magnitude at which bars can be\nsuccessfully measured at the depth and resolution of SDSS. We perform detailed\ndecompositions of 83 S0 galaxies in Coma, 64 from a central sample, and 19 from\na cluster outskirts sample. For the central sample, the S0 bar fraction is\n72^{+5}_{-6}%. This value is significantly higher than that obtained using an\nellipse fitting method for bar detection, 48^{+6}_{-6}%. At a fixed luminosity,\nbarred S0s are redder in (g-r) colour than unbarred S0s by 0.02 mag. The\nfrequency and strength of bars increase towards fainter luminosities. Neither\ncentral metallicity nor stellar age distributions differ significantly between\nbarred and unbarred S0s. There is an increase in the bar fraction towards the\ncluster core, but this is at a low significance level. Bars have at most a weak\ncorrelation with cluster-centric radius." }, { "anchor": "Galaxy And Mass Assembly (GAMA): The environmental dependence of the\n galaxy main sequence: Aims. We aim to investigate if the environment (characterised by the host\ndark matter halo mass) plays any role in shaping the galaxy star formation main\nsequence (MS).\n Methods. The Galaxy and Mass Assembly project (GAMA) combines a spectroscopic\nsurvey with photometric information in 21 bands from the far-ultraviolet (FUV)\nto the far-infrared (FIR). Stellar masses and dust-corrected star-formation\nrates (SFR) are derived from spectral energy distribution (SED) modelling using\nMAGPHYS. We use the GAMA galaxy group catalogue to examine the variation of the\nfraction of star-forming galaxies (SFG) and properties of the MS with respect\nto the environment.\n Results. We examine the environmental dependence for stellar mass selected\nsamples without preselecting star-forming galaxies and study any dependence on\nthe host halo mass separately for centrals and satellites out to z ~ 0.3. We\nfind the SFR distribution at fixed stellar mass can be described by the\ncombination of two Gaussians (referred to as the star-forming Gaussian and the\nquiescent Gaussian). Using the observed bimodality to define SFG, we\ninvestigate how the fraction of SFG F(SFG) and properties of the MS change with\nenvironment. For centrals, the position of the MS is similar to the field but\nwith a larger scatter. No significant dependence on halo mass is observed. For\nsatellites, the position of the MS is almost always lower (by ~0.2 dex)\ncompared to the field and the width is almost always larger. F(SFG) is similar\nbetween centrals (in different halo mass bins) and field galaxies. However, for\nsatellites F(SFG) decreases with increasing halo mass and this dependence is\nstronger towards lower redshift.", "positive": "ATLASGAL --- properties of compact HII regions and their natal clumps: We present a complete sample of molecular clumps containing compact and\nultra-compact (UC) HII regions between \\ell=10\\degr and 60\\degr\\ and\n$|b|<1\\degr, identified by combining the the ATLASGAL submm and CORNISH radio\ncontinuum surveys with visual examination of archival infrared data. Our sample\nis complete to optically thin, compact and UCHII regions driven by a zero age\nmain sequence star of spectral type B0 or earlier embedded within a 1,000 Msun\nclump. In total we identify 213 compact and UCHII regions, associated with 170\nclumps. Unambiguous kinematic distances are derived for these clumps and used\nto estimate their masses and physical sizes, as well as the Lyman continuum\nfluxes and sizes of their embedded HII regions. We find a clear lower envelope\nfor the surface density of molecular clumps hosting massive star formation of\n0.05 g cm^{-2}, which is consistent with a similar sample of clumps associated\nwith 6.7 GHz masers. The mass of the most massive embedded stars is closely\ncorrelated with the mass of their natal clump. Young B stars appear to be\nsignificantly more luminous in the ultraviolet than predicted by current\nstellar atmosphere models. The properties of clumps associated with compact and\nUCHII regions are very similar to those associated with 6.7 GHz methanol masers\nand we speculate that there is little evolution in the structure of the\nmolecular clumps between these two phases. Finally, we identify a significant\npeak in the surface density of compact and UCHII regions associated with the\nW49A star-forming complex, noting that this complex is truly one of the most\nmassive and intense regions of star formation in the Galaxy." }, { "anchor": "LoTSS/HETDEX: Disentangling star formation and AGN activity in\n gravitationally-lensed radio-quiet quasars: Determining the star-forming properties of radio-quiet quasars is important\nfor understanding the co-evolution of star formation and black hole accretion.\nHere, we present the detection of the gravitationally-lensed radio-quiet\nquasars SDSS J1055+4628, SDSS J1313+5151 and SBS 1520+530 at 144 MHz that fall\nin the HETDEX Spring Field targeted in the LOFAR Two-metre Sky Survey (LoTSS)\nfirst full data release. We compare their radio and far-infrared luminosities\nrelative to the radio-infrared correlation and find that their radio\nluminosities can be explained by star formation. The implied star formation\nrates derived from their radio and infrared luminosities are between 20 and 300\n$\\rm{M_{\\odot}~yr^{-1}}$. These detections represent the first study of\ngravitationally lensed sources with LOFAR, opening a new frequency window for\ninvestigating the star-forming properties of high-redshift quasars at radio\nwavelengths. We consider the implications for future data releases and estimate\nthat many of the objects in our parent sample will be detected during LoTSS,\nsignificantly increasing the fraction of gravitationally lensed radio-quiet\nquasars with radio detections.", "positive": "The extension of the Fundamental Metallicity Relation beyond the BPT\n star-forming sequence: evidence for both gas accretion and starvation: The fundamental metallicity relation (FMR) of galaxies is a 3D relation\nbetween the gas-phase metallicity, stellar mass and star-formation rate (SFR).\nIt has been studied so far only for galaxies identified as star-forming (SF) on\nthe BPT diagrams (BPT-SF), but not for galaxies with LI(N)ER/AGN classification\n(BPT-non-SF), mainly due to the lack of diagnostics for estimating their\ngas-phase metallicities in the latter cases. We extend the FMR to BPT-non-SF\ngalaxies. To this end, we exploit the recent nebular line empirical\ncalibrations derived specifically for galaxies classified as non-SF in the BPT\ndiagrams. Moreover, we study an alternative representation of the FMR where we\nconsider the offsets in metallicity and SFR with respect to Main Sequence (MS)\ngalaxies. We find that galaxies with SFR higher than the MS are more metal-poor\nthan their counterparts on the MS, which is interpreted in terms of gas\naccretion, boosting star formation and diluting the metallicity. Low-mass\ngalaxies below the MS (i.e. towards quiescence) have metallicities higher than\ntheir MS counterparts, which is interpreted in terms of starvation, (i.e.\nsuppression of fresh gas supply) hampering star formation and reducing the\ndilution effect, hence resulting in a higher level of internal chemical\nenrichment. Massive galaxies below the MS have gas metallicity much closer to\ntheir MS counterparts and much lower than expected from their stellar\nmetallicities; this result suggests a scenario where massive nearly-quiescent\ngalaxies with LI(N)ER-like nebular emission have recently accreted gas from the\ncircum/intergalactic medium." }, { "anchor": "The JWST Resolved Stellar Populations Early Release Science Program IV:\n The Star Formation History of the Local Group Galaxy WLM: We present the first star formation history (SFH) and age-metallicity\nrelation (AMR) derived from resolved stellar populations imaged with the JWST\nNIRCam instrument. The target is the Local Group star-forming galaxy WLM at 970\nkpc. The depth of the color-magnitude diagram (CMD) reaches below the oldest\nmain sequence turn-off with a SNR=10 at M_F090W=+4.6 mag; this is the deepest\nCMD for any galaxy that is not a satellite of the Milky Way. We use Hubble\nSpace Telescope (HST) optical imaging that overlaps with the NIRCam\nobservations to directly evaluate the SFHs derived based on data from the two\ngreat observatories. The JWST and HST-based SFHs are in excellent agreement. We\nuse the metallicity distribution function measured from stellar spectra to\nconfirm the trends in the AMRs based on the JWST data. Together, these results\nconfirm the efficacy of recovering a SFH and AMR with the NIRCam F090W-F150W\nfilter combination and provide validation of the sensitivity and accuracy of\nstellar evolution libraries in the near-infrared relative to the optical for\nSFH recovery work. From the JWST data, WLM shows an early onset to star\nformation, followed by an extended pause post-reionization before star\nformation re-ignites, which is qualitatively similar to what has been observed\nin the isolated galaxies Leo~A and Aquarius. Quantitatively, 15% of the stellar\nmass formed in the first Gyr, while only 10% formed over the next ~5 Gyr; the\nstellar mass then rapidly doubled in ~2.5 Gyr, followed by constant star\nformation over the last ~5 Gyr.", "positive": "Does the intermediate mass black hole in LEDA 87300 (RGG 118) follow the\n near-quadratic (M_bh)-(M_spheroid) relation?: The mass scaling relation between supermassive black holes and their host\nspheroids has previously been described by a quadratic or steeper relation at\nlow masses (10^5 < M_bh/M_sun < 10^7). How this extends into the realm of\nintermediate mass black holes (10^2 < M_bh/M_sun < 10^5) is not yet clear,\nalthough for the barred Sm galaxy LEDA 87300, Baldassare et al. have recently\nreported a nominal virial mass M_bh=5x10^4 M_sun residing in a `spheroid' of\nstellar mass equal to 6.3x10^8 M_sun. We point out, for the first time, that\nLEDA 87300 therefore appears to reside on the near-quadratic M_bh-M_{sph,*}\nrelation. However, Baldassare et al. modelled the bulge _and_ bar as the single\nspheroidal component of this galaxy. Here we perform a 3-component\nbulge+bar+disk decomposition and find a bulge luminosity which is 7.7 times\nfainter than the published `bulge' luminosity. After correcting for dust we\nfind that M_bulge=0.9x10^8 M_sun, and M_bulge/M_disk=0.04 - which is now in\naccord with ratios typically found in Scd-Sm galaxies. We go on to discuss\nslight revisions to the stellar velocity dispersion (40+/-11 km/s) and black\nhole mass (M_bh=2.9x10^4 M_sun) and show that LEDA 87300 remains consistent\nwith both the M_bh-sigma relation and the near-quadratic M_bh-M_{sph,*}\nrelation when using the reduced bulge mass. LEDA 87300 therefore offers the\nfirst support for the rapid but regulated (near-quadratic) growth of black\nholes, relative to their host bulge/spheroid, extending into the domain of\nintermediate mass black holes." }, { "anchor": "On the origin of the chemical bimodality of disk stars: A tale of merger\n and migration: The Milky Way's stellar disk exhibits a bimodality in the [Fe/H] vs.\n[$\\alpha$/Fe] plane, showing a distinct high-$\\alpha$ and low-$\\alpha$ sequence\nwhose origin is still under debate. We examine the [Fe/H]-[$\\alpha$/Fe]\nabundance plane in cosmological hydrodynamical simulations of Milky Way like\ngalaxies from the NIHAO-UHD project and show that the bimodal $\\alpha$-sequence\nis a generic consequence of a gas-rich merger at some time in the Galaxy's\nevolution. The high-$\\alpha$ sequence evolves first in the early galaxies,\nextending to high metallicities, while it is the low-$\\alpha$ sequence that is\nformed after the gas-rich merger. The merger brings in fresh metal-poor gas\ndiluting the interstellar medium's metallicity while keeping the [$\\alpha$/Fe]\nabundance almost unchanged. The kinematic, structural and spatial properties of\nthe bimodal $\\alpha$-sequence in our simulations reproduces that of\nobservations. In all simulations, the high-$\\alpha$ disk is old, radially\nconcentrated towards the galaxy's center and shows large scale heights. In\ncontrast, the low-$\\alpha$ disk is younger, more radially extended and\nconcentrated to the disk mid-plane. Our results show that the abundance plane\nis well described by these two populations that have been distributed radially\nacross the disk by migration: at present-day in the solar neighbourhood,\nlow-$\\alpha$ stars originate from both the inner and outer disk while most of\nthe high-$\\alpha$ stars have migrated from the inner disk. We show that age\ndating the stars in the [Fe/H]-[$\\alpha$/Fe] plane can constrain the time of\nthe low-$\\alpha$ sequence forming merger and conclude that $\\alpha$-bimodality\nis likely a not uncommon feature of disk galaxies.", "positive": "Properties of hierarchically forming star clusters: We undertake a systematic analysis of the early (< 0.5 Myr) evolution of\nclustering and the stellar initial mass function in turbulent fragmentation\nsimulations. These large scale simulations for the first time offer the\nopportunity for a statistical analysis of IMF variations and correlations\nbetween stellar properties and cluster richness. The typical evolutionary\nscenario involves star formation in small-n clusters which then progressively\nmerge; the first stars to form are seeds of massive stars and achieve a\nheadstart in mass acquisition. These massive seeds end up in the cores of\nclusters and a large fraction of new stars of lower mass is formed in the outer\nparts of the clusters. The resulting clusters are therefore mass segregated at\nan age of 0.5 Myr, although the signature of mass segregation is weakened\nduring mergers. We find that the resulting IMF has a smaller exponent\n(alpha=1.8-2.2) than the Salpeter value (alpha=2.35). The IMFs in subclusters\nare truncated at masses only somewhat larger than the most massive stars (which\ndepends on the richness of the cluster) and an universal upper mass limit of\n150 Msun is ruled out. We also find that the simulations show signs of the\nIGIMF effect proposed by Weidner & Kroupa, where the frequency of massive stars\nis suppressed in the integrated IMF compared to the IMF in individual clusters.\nWe identify clusters through the use of a minimum spanning tree algorithm which\nallows easy comparison between observational survey data and the predictions of\nturbulent fragmentation models. In particular we present quantitative\npredictions regarding properties such as cluster morphology, degree of mass\nsegregation, upper slope of the IMF and the relation between cluster richness\nand maximum stellar mass. [abridged]" }, { "anchor": "Constraining Milky Way mass with Hypervelocity Stars: Context. Although a variety of techniques have been employed for determining\nthe Milky Way dark matter halo mass distribution, the range of allowed masses\nspans both light and heavy values. Knowing the precise mass of our Galaxy is\nimportant for placing the Milky Way in a cosmological $\\Lambda$CDM context.\nAims. We show that hypervelocity stars (HVSs) ejected from the center of the\nMilky Way galaxy can be used to constrain the mass of its dark matter halo.\nMethods. We use the asymmetry in the radial velocity distribution of halo stars\ndue to escaping HVSs, which depends on the halo potential (escape speed) as\nlong as the round trip orbital time is shorter than the stellar lifetime, to\ndiscriminate between different models for the Milky Way gravitational\npotential. Results. Adopting a characteristic HVS travel time of $330$ Myr,\nwhich corresponds to the average mass of main sequence HVSs, we find that\ncurrent data favors a mass for the Milky Way in the range $(1.2$-$1.9)\\times\n10^{12} \\mathrm{M}_\\odot$.", "positive": "A consistency-test for determining whether ultra-compact dwarf galaxies\n could be the remnant nuclei of threshed galaxies: It has been suggested that ultra-compact dwarf (UCD) galaxies are the\n\"threshed'\" remains of larger galaxies. Simulations have revealed that\nextensive tidal-stripping may pare a galaxy back to its tightly-bound, compact\nnuclear star cluster. It has therefore been proposed that the two-component\nnature of UCD galaxies may reflect the original nuclear star cluster surrounded\nby the paltry remnants of its host galaxy. A simple quantitative test of this\ntheory is devised and applied here. If the mass of the central black hole in\nUCD galaxies, relative to the mass of the UCD galaxies' inner stellar\ncomponent, i.e. the suspected nuclear star cluster, matches with the (black\nhole mass)-(nuclear star cluster mass) relation observed in other galaxies,\nthen it would provide quantitative support for the stripped galaxy scenario.\nSuch consistency is found for four of the five UCD galaxies reported to have a\nmassive black hole. The (black hole mass)-(nuclear star cluster mass) relation\nis then used to predict the central black hole mass in two additional UCD\ngalaxies, and to reveal that NGC 205 and possibly NGC 404 (which only has an\nupper limit to its black hole mass) also follow this scaling relation." }, { "anchor": "Evidence of large scale energy cascade in the spiral galaxy NGC 5236: Turbulence plays an important role in the structure and dynamics of the\ngalaxy and influences various processes therein including star formation. In\nthis work, we investigate the large scale turbulence properties of the external\nspiral galaxy NGC 5236. We combine the VLA multi-configuration archival data\nwith the new GMRT observation to estimate the column density and line of sight\nvelocity fluctuation power spectra for this galaxy over almost two decades of\nlength scales. The energy input scale to the ISM turbulence is found to be\naround $6$ kpc. Power spectra of the two-dimensional turbulence in the galaxy's\ndisk follow a power law with a slope $-1.23\\pm0.06$ for the column density and\n$-1.91\\pm0.08$ for the line of sight velocity. The measured power spectra\nslopes strongly suggest in favour of a compressive forcing with a steady energy\ninput of $\\sim 7 \\times 10^{-11}$ erg cm$^{-2}$ sec$^{-1}$. We conclude that\nmuch of these originate from the gravitational instabilities and self-gravity\nin the disk. This is the first and most comprehensive study of turbulence\nstatistics for any external spiral galaxy.", "positive": "Gaia DR2 in 6D: Searching for the fastest stars in the Galaxy: We search for the fastest stars in the subset of stars with radial velocity\nmeasurements of the second data release (DR2) of the European Space Agency\nmission Gaia. Starting from the observed positions, parallaxes, proper motions,\nand radial velocities, we construct the distance and total velocity\ndistribution of more than $7$ million stars in our Milky Way, deriving the full\n6D phase space information in Galactocentric coordinates. These information are\nshared in a catalogue, publicly available at\nhttp://home.strw.leidenuniv.nl/~marchetti/research.html. To search for unbound\nstars, we then focus on stars with a probability greater than $50 \\%$ of being\nunbound from the Milky Way. This cut results in a clean sample of $125$ sources\nwith reliable astrometric parameters and radial velocities. Of these, $20$\nstars have probabilities greater than 80 $\\%$ of being unbound from the Galaxy.\nOn this latter sub-sample, we perform orbit integration to characterize the\nstars' orbital parameter distributions. As expected given the relatively small\nsample size of bright stars, we find no hypervelocity star candidates, stars\nthat are moving on orbits consistent with coming from the Galactic Centre.\nInstead, we find $7$ hyper-runaway star candidates, coming from the Galactic\ndisk. Surprisingly, the remaining $13$ unbound stars cannot be traced back to\nthe Galaxy, including two of the fastest stars (around $700$ km/s). If\nconformed, these may constitute the tip of the iceberg of a large extragalactic\npopulation or the extreme velocity tail of stellar streams." }, { "anchor": "Photoinduced polycyclic aromatic hydrocarbon dehydrogenation: The\n competition between H- and H2-loss: PAHs constitute a major component of the interstellar medium carbon budget,\nlocking up to 10--20% of the elemental carbon. Sequential fragmentation induced\nby energetic photons leads to the formation of new species, including\nfullerenes. However, the exact chemical routes involved in this process remain\nlargely unexplored. In this work, we focus on the first photofragmentation\nsteps, which involve the dehydrogenation of these molecules. For this, we\nconsider a multidisciplinary approach, taking into account the results from\nexperiments, DFT calculations, and modeling using dedicated Monte-Carlo\nsimulations. By considering the simplest isomerization pathways --- i.e.,\nhydrogen roaming along the edges of the molecule --- we are able to\ncharacterize the most likely photodissociation pathways for the molecules\nstudied here. These comprise nine PAHs with clearly different structural\nproperties. The formation of aliphatic-like side groups is found to be critical\nin the first fragmentation step and, furthermore, sets the balance of the\ncompetition between H- and H2-loss. We show that the presence of trio\nhydrogens, especially in combination with bay regions in small PAHs plays an\nimportant part in the experimentally established variations in the odd-to-even\nH-atom loss ratios. In addition, we find that, as PAH size increases, H2\nformation becomes dominant, and sequential hydrogen loss only plays a marginal\nrole. We also find disagreements between experiments and calculations for\nlarge, solo containing PAHs, which need to be accounted for. In order to match\ntheoretical and experimental results, we have modified the energy barriers and\nrestricted the H-hopping to tertiary atoms. The formation of H2 in large PAHs\nupon irradiation appears to be the dominant fragmentation channel, suggesting\nan efficient formation path for molecular hydrogen in PDRs.", "positive": "Galaxy quenching at the high redshift frontier: A fundamental test of\n cosmological models in the early universe with JWST-CEERS: We present an analysis of the quenching of star formation in massive galaxies\n($M_* > 10^{9.5} M_\\odot$) within the first 0.5 - 3 Gyr of the Universe's\nhistory utilizing JWST-CEERS data. We utilize a combination of advanced\nstatistical methods to accurately constrain the intrinsic dependence of\nquenching in a multi-dimensional and inter-correlated parameter space.\nSpecifically, we apply Random Forest (RF) classification, area statistics, and\na partial correlation analysis to the JWST-CEERS data. First, we identify the\nkey testable predictions from two state-of-the-art cosmological simulations\n(IllustrisTNG & EAGLE). Both simulations predict that quenching should be\nregulated by supermassive black hole mass in the early Universe. Furthermore,\nboth simulations identify the stellar potential ($\\phi_*$) as the optimal proxy\nfor black hole mass in photometric data. In photometric observations, where we\nhave no direct constraints on black hole masses, we find that the stellar\npotential is the most predictive parameter of massive galaxy quenching at all\nepochs from $z = 0 - 8$, exactly as predicted by simulations for this sample.\nThe stellar potential outperforms stellar mass, galaxy size, galaxy density,\nand S\\'ersic index as a predictor of quiescence at all epochs probed in\nJWST-CEERS. Collectively, these results strongly imply a stable quenching\nmechanism operating throughout cosmic history, which is closely connected to\nthe central gravitational potential in galaxies. This connection is explained\nin cosmological models via massive black holes forming and growing in deep\npotential wells, and subsequently quenching galaxies through a mix of ejective\nand preventative active galactic nucleus (AGN) feedback." }, { "anchor": "WALLABY Pilot Survey: HI gas kinematics of galaxy pairs in cluster\n environment: We examine the HI gas kinematics of galaxy pairs in two clusters and a group\nusing Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot survey\nobservations. We compare the HI properties of galaxy pair candidates in the\nHydra I and Norma clusters, and the NGC 4636 group, with those of non-paired\ncontrol galaxies selected in the same fields. We perform HI profile\ndecomposition of the sample galaxies using a tool, {\\sc baygaud} which allows\nus to de-blend a line-of-sight velocity profile with an optimal number of\nGaussian components. We construct HI super-profiles of the sample galaxies via\nstacking of their line profiles after aligning the central velocities. We fit a\ndouble Gaussian model to the super-profiles and classify them as kinematically\nnarrow and broad components with respect to their velocity dispersions.\nAdditionally, we investigate the gravitational instability of HI gas disks of\nthe sample galaxies using Toomre Q parameters and HI morphological\ndisturbances. We investigate the effect of the cluster environment on the HI\nproperties of galaxy pairs by dividing the cluster environment into three\nsubcluster regions (i.e., outskirts, infalling and central regions). We find\nthat the denser cluster environment (i.e., infalling and central regions) is\nlikely to impact the HI gas properties of galaxies in a way of decreasing the\namplitude of the kinematically narrow HI gas\n($M_{\\rm{narrow}}^{\\rm{HI}}$/$M_{\\rm{total}}^{\\rm{HI}}$), and increasing the\nToomre Q values of the infalling and central galaxies. This tendency is likely\nto be more enhanced for galaxy pairs in the cluster environment.", "positive": "Quantifying torque from the Milky Way bar using Gaia DR2: We determine the mass of the Milky Way bar and the torque it causes, using\nGaia DR2, by applying the orbital arc method. Based on this, we have found that\nthe gravitational acceleration is not directed towards the centre of our Galaxy\nbut a few degrees away from it. We propose that the tangential acceleration\ncomponent is caused by the bar of the Galaxy. Calculations based on our model\nsuggest that the torque experienced by the region around the Sun is $\\approx\n2400\\, km^2 s^{-2}$ per solar mass. The mass estimate for the bar is $\\sim\n1.6\\pm0.3\\times10^{10} M_\\odot$. Using greatly improved data from Gaia DR2, we\nhave computed the acceleration field to great accuracy by adapting the oPDF\nmethod (Han et al. 2016) locally and used the phase space coordinates of $\\sim\n4\\times10^5$ stars within a distance of 0.5 kpc from the Sun. In the orbital\narc method, the first step is to guess an acceleration field and then\nreconstruct the stellar orbits using this acceleration for all the stars within\na specified region. Next, the stars are redistributed along orbits to check if\nthe overall phase space distribution has changed. We repeat this process until\nwe find an acceleration field that results in a new phase space distribution\nthat is the same as the one that we started with; we have then recovered the\ntrue underlying acceleration." }, { "anchor": "Webb's PEARLS: Bright 1.5--2.0 micron Dropouts in the Spitzer/IRAC Dark\n Field: Using the first epoch of four-band NIRCam observations obtained by the James\nWebb Space Telescope (JWST) Prime Extragalactic Areas for Reionization and\nLensing Science Program in the Spitzer IRAC Dark Field, we search for F150W and\nF200W dropouts. In 14.2 arcmin^2, we have found eight F150W dropouts and eight\nF200W dropouts, all brighter than 27.5 mag (the brightest being ~24 mag) in the\nband to the red side of the break. As they are detected in multiple bands,\nthese must be real objects. Their nature, however, is unclear, and\ncharacterizing their properties is important for realizing the full potential\nof JWST. If the observed color decrements are due to the Lyman break, these\nobjects should be at z >~ 11.7 and z >~ 15.4, respectively. The color\ndiagnostics show that at least four F150W dropouts are far away from the usual\ncontaminators encountered in dropout searches (red galaxies at much lower\nredshifts or brown dwarf stars). While the diagnostics of the F200W dropouts\nare less certain due to the limited number of passbands, at least one of them\nis likely not a known type of contaminant, and the rest are consistent with\neither high-redshift galaxies with evolved stellar populations or old galaxies\nat z ~ 3 to 8. If a significant fraction of our dropouts are indeed at z ~ 12,\nwe have to face the severe problem of explaining their high luminosities and\nnumber densities. Spectroscopic identifications of such objects are urgently\nneeded.", "positive": "Illuminating Galaxy Evolution at Cosmic Noon with ISCEA: the Infrared\n Satellite for Cosmic Evolution Astrophysics: ISCEA (Infrared Satellite for Cosmic Evolution Astrophysics) is a small\nastrophysics mission whose Science Goal is to discover how galaxies evolved in\nthe cosmic web of dark matter at cosmic noon. Its Science Objective is to\ndetermine the history of star formation and its quenching in galaxies as a\nfunction of local density and stellar mass when the Universe was 3-5 Gyrs old\n(1.2\n10 Mpc in each of 50 protocluster (cluster and cosmic web) fields at 1.2 < z <\n2.1. ISCEA measures the star formation quenching factor in those fields, and\ngalaxy kinematics with a precision < 50 km/s to deduce the 3D spatial\ndistribution in each field. ISCEA will transform our understanding of galaxy\nevolution at cosmic noon.\n ISCEA is a small satellite observatory with a 30cm equivalent diameter\naperture telescope with a FoV of 0.32 deg^2, and a multi-object spectrograph\nwith a digital micro-mirror device (DMD) as its programmable slit mask. ISCEA\nwill obtain spectra of 1000 galaxies simultaneously at an effective resolving\npower of R=1000, with 2.8\"x2.8\" slits, over the NIR wavelength range of 1.1 to\n2.0 microns, a regime not accessible from the ground without large gaps in\ncoverage. ISCEA will achieve a pointing accuracy of <= 2\" FWHM over 200s. ISCEA\nwill be launched into a Low Earth Orbit, with a prime mission of 2.5 years.\nISCEA's space-qualification of DMDs opens a new window for spectroscopy from\nspace, enabling revolutionary advances in astrophysics." }, { "anchor": "The Spectral Slope and Kolmogorov Constant of MHD turbulence: The spectral slope of strong MHD turbulence has recently been a matter of\ncontroversy. While Goldreich-Sridhar model (1995) predicts Kolmogorov's -5/3\nslope of turbulence, shallower slopes were often reported by numerical studies.\nWe argue that earlier numerics was affected by driving due to a diffuse\nlocality of energy transfer in MHD case. Our highest-resolution simulation\n(3072^2x1024) has been able to reach the asymptotic -5/3 regime of the energy\nslope. Additionally, we found that so-called dynamic alignment, proposed in the\nmodel with -3/2 slope, saturates and therefore can not affect asymptotic slope.\nThe observation of the asymptotic regime allowed us to measure Kolmogorov\nconstant C_KA=3.2+-0.2 for purely Alfv\\'enic turbulence and C_K=4.1+-0.3 for\nfull MHD turbulence. These values are much higher than the hydrodynamic value\nof 1.64. The larger value of Kolmogorov constant is an indication of a fairly\ninefficient energy transfer and, as we show in this Letter, is in theoretical\nagreement with our observation of diffuse locality. We also explain what has\nbeen missing in numerical studies that reported shallower slopes.", "positive": "Chemistry on Rotating Grain Surface: Ro-Thermal Desorption of Molecules\n from Ice Mantles: It is widely believed that water and complex organic molecules (COMs) first\nform in the ice mantle of dust grains and are subsequently returned into the\ngas due to grain heating by intense radiation of protostars. Previous research\non the desorption of molecules from the ice mantle assumed that grains are at\nrest which is contrary to the fact that grains are suprathermally rotating as a\nresult of their interaction with an anisotropic radiation or gas flow. {To\nclearly understand how molecules are released in to the gas phase, the effect\nof grain suprathermal rotation on surface chemistry must be quantified}. In\nthis paper, we study the effect of suprathermal rotation of dust grains spun-up\nby radiative torques on the desorption of molecules from icy grain mantles\naround protostars. We show that centrifugal potential energy due to grain\nrotation reduces the potential barrier of molecules and significantly enhances\ntheir desorption rate. We term this mechanism {\\it rotational-thermal} or {\\it\nro-thermal} desorption. We apply the ro-thermal mechanism for studying the\ndesorption of molecules from icy grains which are simultaneously heated to high\ntemperatures and spun-up to suprathermal rotation by an intense radiation of\nprotostars. We find that ro-thermal desorption is much more efficient than\nthermal desorption for molecules with high binding energy such as water and\nCOMs. Our results have important implications for understanding the origin of\nCOMs detected in star-forming regions and call for attention to the effect of\nsuprathermal rotation of icy grains to use molecules as a tracer of physical\nconditions of star-forming regions." }, { "anchor": "A VLA Polarimetric Study of the Galactic Center Radio Arc:\n Characterizing Polarization, Rotation Measure, and Magnetic Field Properties: The Radio Arc is one of the brightest systems of non-thermal filaments (NTFs)\nin the Galactic Center, located near several prominent HII regions (Sickle and\nPistol) and the Quintuplet stellar cluster. We present observations of the Arc\nNTFs using the S-, C-, and X-bands of the Very Large Array interferometer. Our\nimages of total intensity reveal large-scale helical features that surround the\nArc NTFs, very narrow sub-filamentation, and compact sources along the NTFs.\nThe distribution of polarized intensity is confined to a relatively small area\nalong the NTFs. There are elongated polarized structures that appear to lack\ntotal intensity counterparts. We detect a range of rotation measure values from\n-1000 to -5800 rad m$\\rm^{-2}$, likely caused by external Faraday rotation\nalong the line of sight. After correcting for Faraday rotation, the intrinsic\nmagnetic field orientation is found to generally trace the extent of the NTFs.\nHowever, the intrinsic magnetic field in several regions of the Arc NTFs shows\nan ordered pattern that is rotated with respect to the extent of the NTFs. We\nsuggest this changing pattern may be caused by an additional magnetized source\nalong the line of sight, so that we observe two field systems superposed in our\nobservations. We suggest that the large scale helical segments near the Radio\nArc could be components of such a source causing these changes in intrinsic\nmagnetic field, and some variations in the polarization and rotation measure\nvalues along the NTFs.", "positive": "Pecular velocities of galaxies in the Leo Spur: Hubble Space Telescope Advanced Camera for Surveys has been used to determine\naccurate distances for the spiral galaxy NGC2683 and 12 other galaxies in a\nzone of the \"local velocity anomaly\" from measurements of the luminosities of\nthe brightest red giant branch stars. These galaxies lie in the Leo Spur, the\nnearest filament beyond our home Local Sheet. The new, accurate distance\nmeasurements confirm that galaxies along the Leo Spur are more distant than\nexpected from uniform cosmic expansion, hence have large peculiar velocities\ntoward us. The motions are generally explained by a previously published model\nthat posits that the Local Sheet is descending at 259 km/s toward the south\nsupergalactic pole due to expansion of the Local Void and being attracted at\n185 km/s toward the Virgo Cluster. With the standard $\\Lambda$CDM cosmology an\nempty void expands at 16 km/s/Mpc so a motion of 259 km/s requires the Local\nVoid to be impressively large and empty. Small residuals from the published\nmodel can be attributed to an upward push toward the north supergalactic pole\nby expansion of the Gemini-Leo Void below the Leo Spur. The Leo Spur is\nsparsely populated but among its constituents there are two associations that\ncontain only dwarf galaxies." }, { "anchor": "ADF22: Blind detections of [CII] line emitters shown to be spurious: We report Atacama Large Millimetre/submillimeter Array (ALMA) Cycle-5\nfollow-up observations of two candidate [CII] emitters at z ~ 6 in the ALMA\ndeep field in SSA22 (ADF22). The candidates were detected blindly in a Cycle-2\nALMA survey covering ~ 5 square arcmins, with a single tuning, along with two\nCO lines associated with galaxies at lower redshifts. Various tests suggested\nat least one of the two > 6-sigma [CII] candidates should be robust (Hayatsu et\nal. 2017). Nevertheless, our new, deeper observations recover neither\ncandidate, demonstrating a higher contamination rate than expected. The cause\nof the spurious detections is under investigation but at present it remains\nunclarified.", "positive": "Galaxy And Mass Assembly (GAMA): Bulge-disk decomposition of KiDS and\n VIKING data in the nearby universe: In this thesis, we derive a catalogue of robust structural parameters for the\ncomponents of a large sample of nearby GAMA galaxies while at the same time\ncontributing to the advancement of image analysis, surface brightness fitting\nand post-processing routines for quality assurance in the context of automated\nlarge-scale bulge-disk decomposition studies. The sample consists of 13096\ngalaxies at redshifts z < 0.08 with imaging data from the Kilo-Degree Survey\nand the VISTA Kilo-Degree INfrared Galaxy survey spanning the optical and\nnear-infrared. We fit three models to the surface brightness distribution of\neach galaxy in each band: a single S\\'ersic model, a S\\'ersic plus exponential\nand a point source plus exponential. The fitting is performed with a fully\nautomated Markov-chain Monte Carlo (MCMC) analysis using the Bayesian\ntwo-dimensional profile fitting code ProFit. All preparatory work is carried\nout using the image analysis package ProFound. After fitting the galaxies, we\nperform model selection and flag galaxies for which none of our models are\nappropriate, mainly mergers and irregular galaxies. The fit quality is assessed\nby visual inspections, comparison to previous works, comparison of independent\nfits of galaxies in the overlap regions between KiDS tiles and bespoke\nsimulations. The latter two are also used for a detailed investigation of\nsystematic error sources. We find that our fit results are robust across\nvarious galaxy types and image qualities with minimal biases. Errors given by\nthe MCMC underestimate the true errors typically by factors 2-3. Automated\nmodel selection criteria are accurate to > 90 % as calibrated by visual\ninspection of a subsample of galaxies. We also present g-r component colours\nand the corresponding colour-magnitude diagram, consistent with previous works\ndespite our increased fit flexibility. All results are integrated into the GAMA\ndatabase." }, { "anchor": "Investigation of dust attenuation and star formation activity in\n galaxies hosting GRBs: The gamma-ray bursts hosts (GRBHs) are excellent targets to study the\nextinction properties of dust and its effects on the global emission of distant\ngalaxies. The dust extinction curve is measured along the GRB afterglow line of\nsight and the analysis of the spectral energy distribution (SED) of the host\ngalaxy gives access to the global dust attenuation of the stellar light. We\nselected a sample of 30 GRBs for which the extinction curve along the GRB\nafterglow line-of-sight (l.o.s) is measured in the rest-frame ultraviolet (UV)\nup to optical and we analysed the properties of the extinction curve as a\nfunction of the host galaxy properties. From these 30 GRBs, we selected seven\nGRBHs with a good rest-frame UV to near infra-red spectral coverage for the\nhost. The attenuation curve was derived by fitting the SEDs of the GRBH sample\nwith the CIGALE SED fitting code. Different star formation histories were\nstudied to recover the star formation rates (SFR) derived using H$_{\\alpha}$\nluminosities. The most extinguished GRBs are preferentially found in the more\nmassive hosts and the UV bump is preferentially found in the most extinguished\nGRB l.o.s. Five out of seven hosts are best fitted with a recent burst of star\nformation, leading to lower stellar mass estimates than previously found. The\naverage attenuation in the host galaxies is about 70% of the amount of\nextinction along the GRB l.o.s. We find a great variety in the derived\nattenuation curves of GRBHs, the UV slope can be similar, flatter or even\nsteeper than the extinction curve slope. We find that the flatter (steeper)\nattenuation curves are found in galaxies with the highest (lowest) SFR and\nstellar masses. The comparison of our results with radiative transfer\nsimulations leads to a uniform distribution of dust and stars in a very clumpy\nISM for half the GRBHs and various dust-stars geometries for the second half of\nthe sample.", "positive": "ZFIRE: The Beginning of the End for Massive Galaxies at z ~ 2 and Why\n Environment Matters: We use ZFIRE and ZFOURGE observations with the Spectral Energy Distribution\n(SED) fitting tool Prospector to reconstruct the star formation histories\n(SFHs) of proto-cluster and field galaxies at $z\\sim 2 $ and compare our\nresults to the TNG100 run of the IllustrisTNG cosmological simulation suite. In\nthe observations, we find that massive proto-cluster galaxies ($\\log[{\\rm\nM}_{\\ast}/{\\rm M}_{\\odot}]>$10.5) form $45 \\pm 8 \\%$ of their total stellar\nmass in the first $2$ Gyr of the Universe compared to $31 \\pm 2 \\%$ formed in\nthe field galaxies. In both observations and simulations, massive proto-cluster\ngalaxies have a flat/declining SFH with decreasing redshift compared to rising\nSFH in their field counterparts. Using IllustrisTNG, we find that massive\ngalaxies ($\\log[{\\rm M}_{\\ast}/{\\rm M}_{\\odot}] \\geq 10.5$) in both\nenvironments are on average $\\approx190$ Myr older than low mass galaxies\n($\\log[{\\rm M}_{\\ast}/{\\rm M}_{\\odot}]= 9-9.5$). However, the difference in\nmean stellar ages of cluster and field galaxies is minimal when considering the\nfull range in stellar mass ($\\log[{\\rm M}_{\\ast}/{\\rm M}_{\\odot}] \\geq 9$). We\nexplore the role of mergers in driving the SFH in IllustrisTNG and find that\nmassive cluster galaxies consistently experience mergers with low gas fraction\ncompared to other galaxies after 1 Gyr from the Big Bang. We hypothesize that\nthe low gas fraction in the progenitors of massive cluster galaxies is\nresponsible for the reduced star formation." }, { "anchor": "Correlation Analysis for Gamma-ray (radio) and Broad Line Emissions of\n Fermi Blazars: In this work, we compiled a sample of 202 Fermi/LAT blazars with available\nbroad line emissions. Out of the 202 sources, 66 have known Doppler factors.\nThe correlation between ($\\gamma$-ray) and broad-line emission, and that\nbetween radio and broad-line emission are investigated by removing the effects\nof redshift and beaming boosting for the whole sample and the subclasses, flat\nspectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs) respectively.\nWe obtained a strong positive correlation between ($\\gamma$-ray) and broad-line\nemission and between radio and broad-line emission for the 202 blazars; It is\nworth noting that the correlation still exists after removing redshift effect.\nFor the 66 sources with Doppler factors, there is also a positive correlation\nbetween ($\\gamma$-ray) and broad-line emission after removing the Doppler\nfactors, as well as that between radio and broad-line emission. Our analysis\nsuggest that 1. There are strong correlations between the ($\\gamma$-ray) and\nthe broad line emission for the whole blazar sample and their subclasses. The\ncorrelations exist when the redshift effect is removed for the whole sample and\ntheir subclasses, confirming the results by Ghisellini et al. (2014) and Chen\n(2018). 2. For the 66 blazars with available Doppler factors, a strong\ncorrelation between the broad line emission and the Doppler factor is found.\nThe correlation between the ($\\gamma$-ray) and the broad line emission exists\nafter the Doppler factor effect is removed. Similar results for 1 and 2 also\nobtained between radio and broad-line emission. 3. Our analysis suggests a\nrobust connection between the accretion process and the jet.", "positive": "HST/COS Detection of Deuterated Molecular Hydrogen in a DLA at z = 0.18: We report on the detection of deuterated molecular hydrogen, HD, at $z =\n0.18$. HD and H$_{\\rm 2}$ are detected in HST/COS data of a low metallicity ($Z\n\\sim 0.07Z_\\odot$) damped Ly$\\alpha$ system at $z = 0.18562$ toward QSO\nB0120$-$28, with log $N$(H I) = 20.50 $\\pm$ 0.10. Four absorption components\nare clearly resolved in H$_{\\rm 2}$ while two components are resolved in HD;\nthe bulk of the molecular hydrogen is associated with the components traced by\nHD. We find total column densities log $N$(HD) = 14.82 $\\pm$ 0.15 and log\n$N$(H$_{\\rm 2}$) = 20.00 $\\pm$ 0.10. This system has a high molecular fraction,\n$f$(H$_{\\rm 2}$) = 0.39 $\\pm$ 0.10 and a low HD to H$_{\\rm 2}$ ratio, log\n(HD/2H$_{\\rm 2}$) $= -5.5 \\pm 0.2$ dex. The excitation temperature, $T_{01} =\n65 \\pm 2$ K, in the component containing the bulk of the molecular gas is lower\nthan in other DLAs. These properties are unlike those in other higher redshift\nDLA systems known to contain HD, but are consistent with what is observed in\ndense clouds in the Milky Way." }, { "anchor": "Observational signatures of the dust size evolution in isolated galaxy\n simulations: We aim to provide observational signatures of the dust size evolution in the\nISM, in particular exploring indicators of polycyclic aromatic hydrocarbon\n(PAH) mass fraction ($q_{PAH}$) defined as the mass fraction of PAHs relative\nto total dust grains. Additionally, we validate our dust evolution model by\ncomparing the observational signatures from our simulations to those from\nobservations. We model the evolution of grain size distribution of Milky\nWay-like and NGC 628-like galaxies representing star-forming galaxies with a\nhydrodynamic simulation code, GADGET4-OSAKA, which considers dust production\nand interstellar processing. Furthermore, we perform post-processing dust\nradiative transfer with SKIRT based on the simulations to predict the\nobservational properties. We find that the intensity ratio between 8 um and 24\num correlates with $q_{PAH}$ and can be used as an indicator of PAH mass\nfraction. However, this ratio is influenced by the radiation field. As another\nindicator, we suggest the 8 um-to-total infrared intensity ratio ($\\nu I_\\nu(8\n\\mu m)/I$(TIR)), which tightly correlates with $q_{PAH}$. Furthermore, we\nexplore the spatial evolution of $q_{PAH}$ in the simulated Milky Way-like\ngalaxy using $\\nu I_\\nu(8 \\mu m)/I$(TIR). We find that the spatially resolved\n$q_{PAH}$ increases with metallicity at lower metallicity (Z<0.2 Zsun) due to\nthe interplay between accretion and shattering while it decreases with\nmetallicity at higher metallicity (Z>0.2 Zsun) due to coagulation. Finally, we\ncompare the above indicators in the NGC 628-like simulation with those observed\nin NGC 628. Consequently, our simulation underestimates the PAH mass fraction\nthroughout the entire galaxy. This is probably because PAH is too efficiently\nlost by coagulation in the interstellar medium in our model, which suggests\nthat the inhibition of coagulation of the PAHs is key to enhancing PAH\nformation.", "positive": "The spatial extension of extended narrow line regions in MaNGA AGN: In this work, we revisit the size-luminosity relation of the extended narrow\nline regions (ENLRs) using a large sample of nearby active galactic nuclei\n(AGN) from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA)\nsurvey. The ENLRs ionized by the AGN are identified through the spatially\nresolved BPT diagram, which results in a sample of 152 AGN. By combining our\nAGN with the literature high-luminosity quasars, we found a tight log-linear\nrelation between the size of the ENLR and the AGN [O III]{\\lambda}5007{\\AA}\nluminosity over four orders of magnitude of the [O III] luminosity. The slope\nof this relation is 0.42 $\\pm$ 0.02 which can be explained in terms of a\ndistribution of clouds photoionized by the AGN. This relation also indicates\nthe AGN have the potential to ionize and heat the gas clouds at a large\ndistance from the nuclei without the aids of outflows and jets for the\nlow-luminosity Seyferts." }, { "anchor": "The Heraklion Extragalactic Catalogue (HECATE): a value-added galaxy\n catalogue for multi-messenger astrophysics: We present the Heraklion Extragalactic Catalogue, or HECATE, an all-sky\nvalue-added galaxy catalogue, aiming to facilitate present and future\nmulti-wavelength and multi-messenger studies in the local Universe. It contains\n204,733 galaxies up to a redshift of 0.047 (D<200 Mpc), and it is >50% complete\nin terms of the B-band luminosity density at distances in the 0-170 Mpc range.\nBy incorporating and homogenising data from astronomical databases and\nmulti-wavelength surveys, the catalogue offers positions, sizes, distances,\nmorphological classifications, star-formation rates, stellar masses,\nmetallicities, and nuclear activity classifications. This wealth of information\ncan enable a wide-range of applications, such as: (i) demographic studies of\nextragalactic sources, (ii) initial characterisation of transient events, and\n(iii) searches for electromagnetic counterparts of gravitational-wave events.\nThe catalogue is publicly available to the community at a dedicated portal,\nwhich will also host future extensions in terms of the covered volume, and data\nproducts.", "positive": "A complete disclosure of the hidden type-1 AGN in NGC 1068 thanks to 52\n years of broadband polarimetric observation: We create the first broadband polarization spectrum of an active galactic\nnucleus (AGN) by compiling the 0.1 - 100 microns, 4.9 GHz and 15 GHz continuum\npolarization of NGC 1068 from more than 50 years of observations. Despite the\ndiversity of instruments and apertures, the observed spectrum of linear\ncontinuum polarization has distinctive wavelength-dependent signatures that can\nbe related to the AGN and host galaxy physics. The impact of the Big Blue bump\nand infrared bump, together with electron, Mie scattering, dichroism and\nsynchrotron emission are naturally highlighted in polarization, allowing us to\nreveal the type-1 AGN core inside this type-2 object with unprecedented\nprecision. In order to isolate the AGN component, we reconstruct the spectral\nenergy distribution of NGC 1068 and estimate the fraction of diluting light in\nthe observed continuum flux. This allows us to clearly and independently show\nthat, in the case of NGC 1068, Thomson scattering is the dominant mechanism for\nthe polarization in the optical band. We also investigate the effect of\naperture on the observed polarization and confirm previous findings on the\nextension of the narrow line region of NGC 1068 and on the B-band and K-band\npolarization from the host. Finally, we do not detect statistically significant\naperture-corrected polarimetric variations over the last 52 years, suggesting\nthat the parsec-scale morphological and magnetic geometries probably remained\nstable for more than half a century." }, { "anchor": "The R1R2' outer ring revealed by young open cluster data: The distribution of young open clusters in the Galactic plane suggests the\nexistence of the outer ring R1R2' in the Galaxy. The solar position angle\ntheta_b providing the best agreement between the observed and model\ndistribution is theta_b=35 +\\- 10 degrees. We compared the theta_b values\nderived from three different catalogues of open cluster and they appear to be\nconsistent within the errors.", "positive": "Scintillation Arc Brightness and Electron Density for an Analytical\n Noodle Model: We show that narrow filaments or sheets of over- or under-dense plasma, or\n\"noodles,\" with fluctuations of scattering phase of less than a radian, can\nform the scintillation arcs seen for many pulsars. The required local\nfluctuations of electron density are indefinitely small. We assume a cosine\nprofile for the electron column and find the scattered field by analytic\nKirchhoff integration. For a large electron column, corresponding to large\namplitude of phase variation, the stationary-phase approximation is accurate;\nwe call this regime \"ray optics\". For smaller-amplitude phase variation, the\nstationary-phase approximation is inaccurate or inapplicable; we call this\nregime \"wave optics\". We show that scattering is most efficient when the width\nof the strip equals that of one pair of Fresnel zones, and in the wave-optics\nregime. We show that the resolution of present observations is about 100\nFresnel zones on the scattering screen. Incoherent superposition of strips\nwithin a resolution element tends to increase the scattered field. We find that\nobservations match a single noodle per resolution element with phase of up to\n12 radians; or many noodles per resolution element with arbitrarily small phase\nvariation each, for net phase of less than a radian. Observations suggest a\nminimum radius for noodles of about 650 km, comparable to the ion inertial\nscale or the ion cyclotron radius in the scattering plasma." }, { "anchor": "Stellar halos from The Dragonfly Edge-on Galaxies Survey: We present the primary results from the Dragonfly Edge-on Galaxies Survey\n(DEGS), an exploration of the stellar halos of twelve nearby ($d < 25$ Mpc)\nedge-on disc galaxies with the Dragonfly Telephoto Array. The edge-on\norientation of these galaxies allows their stellar halos to be explored with\nminimal obscuration by or confusion with the much brighter disc light. Galaxies\nin the sample span a range of stellar masses from $10^{9.68} - 10^{10.88}\nM_\\odot$. We confirm that the wide range of stellar halo mass fractions\npreviously seen for Milky Way-mass galaxies is also found among less massive\nspiral galaxies. The scatter in stellar halo mass fraction is large but we do\nfind a significant positive correlation between stellar halo mass fraction and\ntotal stellar mass when the former is measured beyond five half-mass radii.\nReasonably good agreement is found with predictions from cosmological\nhydrodynamical simulations, although observed stellar halo fractions appear to\nbe somewhat lower than expected from these simulations.", "positive": "Radiation-pressure Waves and Multiphase Quasar Outflows: We report on quasar outflow properties revealed by analyzing more than 60\ncomposite outflow spectra built from $\\sim 60\\,000$ CIV absorption troughs in\nthe SDSS-III/BOSS DR12QBAL catalog. We assess the dependences of the equivalent\nwidths of many outflow metal absorption features on outflow velocity, trough\nwidth and position, and quasar magnitude and redshift. The evolution of the\nequivalent widths of the OVI and NV lines with outflow velocity correlates with\nthat of the mean absorption-line width, the outflow electron density, and the\nstrength of lines arising from collisionally-excited meta-stable states. None\nof these correlations is found for the other high- or low-ionization species,\nand different behaviors with trough width are also suggested. We find no\ndependence on quasar magnitude or redshift in any case. All the observed trends\ncan be reconciled by considering a multiphase stratified outflow structure,\nwhere inner regions are colder, denser and host lower-ionization species. Given\nthe prevalence of radiative acceleration in quasar outflows found by Mas-Ribas\n& Mauland (2019), we suggest that radiation pressure sweeps up and compresses\nthe outflowing gas outwards, creating waves or filaments where the multiphase\nstratified structure could take form. This scenario is supported by the\nsuggested correlation between electron density and outflow velocity, and the\nsimilar behavior observed for the line and line-locking components of the\nabsorption features. We show that this outflow structure is also consistent\nwith other X-ray, radiative transfer, and polarization results, and discuss the\nimplications of our findings for future observational and numerical quasar\noutflow studies." }, { "anchor": "Galaxy Zoo: Clump Scout -- Design and first application of a\n two-dimensional aggregation tool for citizen science: Galaxy Zoo: Clump Scout is a web-based citizen science project designed to\nidentify and spatially locate giant star forming clumps in galaxies that were\nimaged by the Sloan Digital Sky Survey Legacy Survey. We present a\nstatistically driven software framework that is designed to aggregate\ntwo-dimensional annotations of clump locations provided by multiple independent\nGalaxy Zoo: Clump Scout volunteers and generate a consensus label that\nidentifies the locations of probable clumps within each galaxy. The statistical\nmodel our framework is based on allows us to assign false-positive\nprobabilities to each of the clumps we identify, to estimate the skill levels\nof each of the volunteers who contribute to Galaxy Zoo: Clump Scout and also to\nquantitatively assess the reliability of the consensus labels that are derived\nfor each subject. We apply our framework to a dataset containing 3,561,454\ntwo-dimensional points, which constitute 1,739,259 annotations of 85,286\ndistinct subjects provided by 20,999 volunteers. Using this dataset, we\nidentify 128,100 potential clumps distributed among 44,126 galaxies. This\ndataset can be used to study the prevalence and demographics of giant star\nforming clumps in low-redshift galaxies. The code for our aggregation software\nframework is publicly available at:\nhttps://github.com/ou-astrophysics/BoxAggregator", "positive": "SDSS--IV MaNGA : The Inner Density Slopes of nearby galaxies: We derive the mass weighted total density slopes within the effective\n(half-light) radius, $\\gamma'$, for more than 2000 nearby galaxies from the\nSDSS-IV MaNGA survey using Jeans-anisotropic-models applied to IFU\nobservations. Our galaxies span a wide range of the stellar mass ($10^9$\n$M_{\\rm \\odot}< M_* < 10^{12}$ M$_{\\odot}$) and the velocity dispersion (30\nkm/s $< \\sigma_v <$ 300 km/s). We find that for galaxies with velocity\ndispersion $\\sigma_v>100$ km/s, the density slope has a mean value $\\langle\n\\gamma^{\\prime} \\rangle = 2.24$ and a dispersion $\\sigma_{\\gamma}=0.22$, almost\nindependent of velocity dispersion. A clear turn over in the $\\gamma'-\\sigma_v$\nrelation is present at $\\sigma\\sim 100$ km/s, below which the density slope\ndecreases rapidly with $\\sigma_v$. Our analysis shows that a large fraction of\ndwarf galaxies (below $M_* = 10^{10}$ M$_{\\odot}$) have total density slopes\nshallower than 1, which implies that they may reside in cold dark matter halos\nwith shallow density slopes. We compare our results with that of galaxies in\nhydrodynamical simulations of EAGLE, Illustris and IllustrisTNG projects, and\nfind all simulations predict shallower density slopes for massive galaxies with\nhigh $\\sigma_v$. Finally, we explore the dependence of $\\gamma'$ on the\npositions of galaxies in halos, namely centrals vs. satellites, and find that\nfor the same velocity dispersion, the amplitude of $\\gamma'$ is higher for\nsatellite galaxies by about 0.1." }, { "anchor": "From Carbon to Cobalt: Chemical compositions and ages of $z\\sim0.7$\n quiescent galaxies: We present elemental abundance patterns (C, N, Mg, Si, Ca, Ti, V, Cr, Fe, Co,\nand Ni) for a population of 135 massive quiescent galaxies at $z\\sim0.7$ with\nultra-deep rest-frame optical spectroscopy drawn from the LEGA-C survey. We\nderive average ages and elemental abundances in four bins of stellar velocity\ndispersion ($\\sigma_v$) ranging from 150$~$km$\\,$s$^{-1}$ to\n250$~$km$\\,$s$^{-1}$ using a full-spectrum hierarchical Bayesian model. The\nresulting elemental abundance measurements are precise to 0.05$\\,$dex. The\nmajority of elements, as well as the total metallicity and stellar age, show a\npositive correlation with $\\sigma_v$. Thus, the highest dispersion galaxies\nformed the earliest and are the most metal-rich. We find only mild or\nnon-significant trends between [X/Fe] and $\\sigma_v$, suggesting that the\naverage star-formation timescale does not strongly depend on velocity\ndispersion. To first order, the abundance patterns of the $z\\sim0.7$ quiescent\ngalaxies are strikingly similar to those at $z\\sim0$. However, at the lowest\nvelocity dispersions the $z\\sim0.7$ galaxies have slightly enhanced N, Mg, Ti,\nand Ni abundance ratios and earlier formation redshifts than their $z\\sim0$\ncounterparts. Thus, while the higher-mass quiescent galaxy population shows\nlittle evolution, the low-mass quiescent galaxies population has grown\nsignificantly over the past six billion years. Finally, the abundance patterns\nof both $z\\sim0$ and $z\\sim0.7$ quiescent galaxies differ considerably from\ntheoretical prediction based on a chemical evolution model, indicating that our\nunderstanding of the enrichment histories of these galaxies is still very\nlimited.", "positive": "The NGC 7742 star cluster luminosity function: A population analysis\n revisited: We re-examine the properties of the star cluster population in the\ncircumnuclear starburst ring in the face-on spiral galaxy NGC 7742, whose young\ncluster mass function has been reported to exhibit significant deviations from\nthe canonical power law. We base our reassessment on the clusters' luminosities\n(an observational quantity) rather than their masses (a derived quantity), and\nconfirm conclusively that the galaxy's starburst-ring clusters---and\nparticularly the youngest subsample, $\\log(t \\mbox{ yr}^{-1}) \\le 7.2$---show\nevidence of a turnover in the cluster luminosity function well above the 90\\%\ncompleteness limit adopted to ensure the reliability of our results. This\nconfirmation emphasises the unique conundrum posed by this unusual cluster\npopulation." }, { "anchor": "ACACIA: a new method to produce on-the-fly merger trees in the RAMSES\n code: The implementation of ACACIA, a new algorithm to generate dark matter halo\nmerger trees with the Adaptive Mesh Refinement (AMR) code RAMSES, is presented.\nThe algorithm is fully parallel and based on the Message Passing Interface\n(MPI). As opposed to most available merger tree tools, it works on the fly\nduring the course of the N body simulation. It can track dark matter\nsubstructures individually using the index of the most bound particle in the\nclump. Once a halo (or a sub-halo) merges into another one, the algorithm still\ntracks it through the last identified most bound particle in the clump,\nallowing to check at later snapshots whether the merging event was definitive,\nor whether it was only temporary, with the clump only traversing another one.\nThe same technique can be used to track orphan galaxies that are not assigned\nto a parent clump anymore because the clump dissolved due to numerical\nover-merging. We study in detail the impact of various parameters on the\nresulting halo catalogues and corresponding merger histories. We then compare\nthe performance of our method using standard validation diagnostics,\ndemonstrating that we reach a quality similar to the best available and\ncommonly used merger tree tools. As a proof of concept, we use our merger tree\nalgorithm together with a parametrised stellar-mass-to-halo-mass relation and\ngenerate a mock galaxy catalogue that shows good agreement with observational\ndata.", "positive": "A simple model for mixing and cooling in cloud-wind interactions: We introduce a simple entropy-based formalism to characterize the role of\nmixing in pressure-balanced multiphase clouds, and demonstrate example\napplications using Enzo-E (magneto)hydrodynamic simulations. Under this\nformalism, the high-dimensional description of the system's state at a given\ntime is simplified to the joint distribution of mass over pressure ($P$) and\nentropy ($K=P/\\rho^\\gamma$). As a result, this approach provides a way for\n(empirically and analytically) quantifying the impact of different initial\nconditions and sets of physics on the system evolution. We find that mixing\npredominantly alters the distribution along the $K$ direction and illustrate\nhow the formalism can be used to model mixing and cooling for fluid elements\noriginating in the cloud. We further confirm and generalize a previously\nsuggested criterion for cloud growth in the presence of radiative cooling, and\ndemonstrate that the shape of the cooling curve, particularly at the low\ntemperature end, can play an important role in controlling condensation.\nMoreover, we discuss the capacity of our approach to generalize such a\ncriterion to apply to additional sets of physics, and to build intuition for\nthe impact of subtle higher order effects not directly addressed by the\ncriterion." }, { "anchor": "A global galactic dynamo with a corona constrained by relative helicity: We present a model for a global axisymmetric turbulent dynamo operating in a\ngalaxy with a corona which treats the supernovae (SNe) and magneto-rotational\ninstability (MRI) driven turbulence parameters under a common formalism. The\nnonlinear quenching of the dynamo is alleviated by inclusion of small-scale\nadvective and diffusive magnetic helicity fluxes, which allow the gauge\ninvariant magnetic helicity to be transferred outside the disk and consequently\nbuild up a corona during the course of dynamo action. The time-dependent dynamo\nequations are expressed in a separable form and solved through an eigenvector\nexpansion constructed using the steady-state solutions of the dynamo equation.\nThe parametric evolution of the dynamo solution allows us to estimate the final\nstructure of the global magnetic field and the saturated value of the\nturbulence parameter $\\alpha_m$, even before solving the dynamical equations\nfor evolution of magnetic fields in the disk and the corona, along with\n$\\alpha$-quenching. We then solve these equations simultaneously to study the\nsaturation of large-scale magnetic field, its dependence on the small-scale\nmagnetic helicity fluxes and corresponding evolution of the force-free field in\nthe corona. The quadrupolar large-scale magnetic field in the disk is found to\nreach equipartition strength within a timescale of 1 Gyr. The large-scale\nmagnetic field in the corona obtained is much weaker in strength compared to\nthe field inside the disk and has only a weak impact on the dynamo operation.", "positive": "Interstellar Dust Models and Evolutionary Implications: The wavelength dependences of interstellar extinction and polarization,\nsupplemented by observed elemental abundances and the spectrum of infrared\nemission from dust heated by starlight, strongly constrain dust models. One\ndust model that appears to be consistent with observations is presented. To\nreproduce the observed extinction, the model consumes the bulk of interstellar\nMg, Si, and Fe (in amorphous silicates), and a substantial fraction of C (in\ncarbonaceous material), with size distributions and alignment adjusted to match\nobservations.\n The composition, structure, and size distribution of interstellar grains is\nthe result of injection of dust from stellar outflows into the interstellar\nmedium (ISM), followed by destruction, growth, coagulation, and photoprocessing\nof interstellar grains. The balance among these poorly-understood processes is\nresponsible for the mix of solid material present in the ISM. Most interstellar\ngrain material present in the diffuse ISM must be grown in the ISM. The\namorphous silicate and carbonaceous materials that form the bulk of\ninterstellar dust must therefore be the result of grain growth in the presence\nof ultraviolet radiation. Dust in high-z systems such as J1148+5251 is also\nproduced primarily in the ISM, with supernova-produced dust contributing only a\nsmall fraction of the total dust mass." }, { "anchor": "Reverberation measurement of the inner radius of the dust torus in NGC\n 4151 during 2008-2013: We investigate the correlation between infrared (JHKL) and optical (B) fluxes\nof the variable nucleus of the Seyfert galaxy NGC 4151 using partially\npublished data for the last 6 years (2008-2013.). Here we are using the same\ndata as in Oknyansky et al. (2014), but include also optical (B) data from Guo\net al. We find that the lag of flux in all the infrared bands is the same, 40\n+- 6 days, to within the measurement accuracy. Variability in the J and K bands\nis not quite simultaneous, perhaps due to the differing contributions of the\naccretion disk in these bands. The lag found for the K band compared with the B\nband is not significantly different from earlier values obtained for the period\n2000-2007. However, finding approximately the same lags in all IR bands for\n2008-2013 differs from previous results at earlier epochs when the lag\nincreased with increasing wavelength. Examples of almost the same lag in\ndifferent IR bands are known for some other active nuclei. In the case of NGC\n4151 it appears that the relative lags between the IR bands may be different in\ndifferent years. The available data, unfortunately, do not allow us to\ninvestigate a possible change in the lags during the test interval. We discuss\nour results in the framework of the standard model where the variable infrared\nradiation is mainly due to thermal re-emission from the part of the dusty torus\nclosest to the central source. There is also a contribution of some IR emission\nfrom the accretion disk, and this contribution increases with decreasing\nwavelength. Some cosmological applications of obtained results are discussed.", "positive": "Evolution of the Stellar Mass Function in Multiple-Population Globular\n Clusters: We present the results of a survey of N-body simulations aimed at studying\nthe effects of the long-term dynamical evolution on the stellar mass function\n(MF) of multiple stellar populations in globular clusters. Our simulations show\nthat if first-(1G) and second-generation (2G) stars have the same initial MF\n(IMF), the global MFs of the two populations are affected similarly by\ndynamical evolution and no significant differences between the 1G and the 2G\nMFs arise during the cluster's evolution. If the two populations have different\nIMFs, dynamical effects do not completely erase memory of the initial\ndifferences. Should observations find differences between the global 1G and 2G\nMF, these would reveal the fingerprints of differences in their IMFs.\nIrrespective of whether the 1G and 2G populations have the same global IMF or\nnot, dynamical effects can produce differences between the local (measured at\nvarious distances from the cluster centre) 1G and 2G MFs; these differences are\na manifestation of the process of mass segregation in populations with\ndifferent initial structural properties. In dynamically old and spatially mixed\nclusters, however, differences between the local 1G and 2G MFs can reveal\ndifferences between the 1G and 2G global MFs. In general, for clusters with any\ndynamical age, large differences between the local 1G and 2G MFs are more\nlikely to be associated with differences in the global MF. Our study also\nreveals a dependence of the spatial mixing rate on the stellar mass, another\ndynamical consequence of the multiscale nature of multiple-population clusters." }, { "anchor": "Gaia-EDR3 Parallax Distances to the Great Carina Nebula and its Star\n Clusters (Trumpler 14, 15, 16): Using offset-corrected Gaia-EDR3 parallax measurements and spectrophotometric\nmethods, we have determined distances for 69 massive stars in the Carina OB1\nassociation and associated clusters: Trumpler 16 (21 stars), Trumpler 14 (20\nstars), Trumpler 15 (3 stars), Bochum 11 (5 stars), and South Pillars region\n(20 stars). Past distance estimates to the Carina Nebula range from 2.2 to 3.6\nkpc, with uncertainties arising from photometry and anomalous dust extinction.\nThe EDR3 parallax solutions show considerable improvement over DR2, with\ntypical errors $\\sigma_{\\varpi}/\\varpi \\approx$~3-5%. The O-type stars in the\nGreat Carina Nebula lie at essentially the same distance ($2.35\\pm0.08$ kpc),\nquoting mean and rms variance. The clusters have distances of $2.32\\pm0.12$ kpc\n(Tr 16), $2.37\\pm0.15$ kpc (Tr 14), $2.36\\pm0.09$ kpc (Tr 15), and\n$2.33\\pm0.12$ kpc (Bochum 11) in good agreement with the $\\eta$ Car distance of\naround 2.3 kpc. O-star proper motions suggest internal (2D) velocity\ndispersions $\\sim4$ km/s for Tr 14 and Tr 16. Reliable distances allow\nestimates of cluster sizes, stellar dynamics, luminosities, and fluxes of\nphotoionizing radiation incident on photodissociation regions in the region. We\nestimate that Tr 14 and Tr 16 have half-mass radii $r_h = 1.5-1.8$ pc, stellar\ncrossing times $t_{\\rm cr} = r_h/v_m \\approx 0.7-0.8$ Myr, and two-body\nrelaxation times $t_{rh} \\approx 40-80$ Myr. The underlying velocity dispersion\nfor Tr 14, if a bound cluster, would be $v_m \\approx 2.1^{+0.7}_{-0.4}$ km/s\nfor $N = 7600^{+5800}_{-2600}$ stars. With the higher dispersions of the\nO-stars, mass segregation might occur slowly, on times scales of 3-6~Myr.", "positive": "Downsizing of Star Formation Measured from the Clustered Infrared\n Background Correlated with Quasars: Powerful quasars can be seen out to large distances. As they reside in\nmassive dark matter haloes, they provide a useful tracer of large scale\nstructure. We stack Herschel-SPIRE images at 250, 350 and 500 microns at the\nlocation of 11,235 quasars in ten redshift bins spanning $0.5 \\leq z \\leq 3.5$.\nThe unresolved dust emission of the quasar and its host galaxy dominate on\ninstrumental beam scales, while extended emission is spatially resolved on\nphysical scales of order a megaparsec. This emission is due to dusty\nstar-forming galaxies clustered around the dark matter haloes hosting quasars.\nWe measure radial surface brightness profiles of the stacked images to compute\nthe angular correlation function of dusty star-forming galaxies correlated with\nquasars. We then model the profiles to determine large scale clustering\nproperties of quasars and dusty star-forming galaxies as a function of\nredshift. We adopt a halo model and parameterize it by the most effective halo\nmass at hosting star-forming galaxies, finding $\\log(M_\\mathrm{eff}/M_{\\odot})\n= 13.8^{+0.1}_{-0.1}$ at $z=2.21-2.32$, and, at $z=0.5-0.81$, the mass is\n$\\log(M_\\mathrm{eff}/M_{\\odot}) = 10.7^{+1.0}_{-0.2}$. Our results indicate a\ndownsizing of dark matter haloes hosting dusty star-forming galaxies between\n$0.5 \\leq z \\leq 2.9$. The derived dark matter halo masses are consistent with\nother measurements of star-forming and sub-millimeter galaxies. The physical\nproperties of dusty star-forming galaxies inferred from the halo model depend\non details of the quasar halo occupation distribution in ways that we explore\nat $z>2.5$, where the quasar HOD parameters are not well constrained." }, { "anchor": "Chromatically modelling the parsec scale dusty structure in the centre\n of NGC1068: The Very Large Telescope Interferometer (VLTI) has been providing\nbreakthrough images of the dust in the central parsecs of Active Galactic\nNuclei (AGN), a key component of the AGN unification scheme and AGN host galaxy\ninteraction. In single IR bands, the images can have multiple interpretations\nsome of which could challenge the unification scheme. This is the case for the\narchetypal type 2 AGN of NGC1068. The ambiguity is reduced by multi-band\ntemperature maps which are hindered by uncertainty in intra-band alignment. We\ncreate a chromatic model capable of simultaneously explaining the VLTI\nGRAVITY+MATISSE 2$\\mu$m-13$\\mu$m observations of the AGN in NGC1068. We use a\nsimple disk and wind geometry populated with spherical black body emitters and\ndust obscuration to create a versatile multi-wavelength model for IR\ninterferometric data of dusty objects. This simple geometry is capable of\nreproducing the K-N-band VLTI data, explains the complex single band images,\nand solves the alignment between bands. We find that the resulting geometry is\nconsistent with previous studies. Compared to molecular gas emission, our model\nwind position angle (PA) of $22^3_2{\\deg}$ is close to the mas scale outflowing\nCO(6-5) PA of ~33{\\deg} seen with the ALMA. The equivalent 90{\\deg} offset\nmodel disk PA is also consistent with the CO(6-5) disk axis of 112{\\deg} as\nwell as the mas scale disk axis from CO(2-1), CO(3-2), and HCO$^+$(4-3) of\n115$\\pm$5{\\deg}. Furthermore, the resulting model visually resembles the\nequivalent achromatic image reconstructions. We conclude that the IR emitting\nstructure surrounding the AGN can indeed be explained by the clumpy disk+wind\niteration of the AGN unification scheme. Within the scheme, we find it is best\nexplained as a type 2 and the obscuring dust chemistry is consistent with a mix\nof olivine silicates and 16$\\pm$1% amorphous carbon.", "positive": "An analysis of the composite stellar population in M32: We obtained long-slit spectra of high signal-to-noise ratio of the galaxy M32\nwith the GMOS spectrograph at the GEMINI North telescope. We analysed the\nintegrated spectra by means of full spectral fitting in order to extract the\nmixture of stellar populations that best represents its composite nature. Three\ndifferent galactic radii were analysed, from the nuclear region out to 2 arcmin\nfrom the centre. This allows us to compare, for the first time, the results of\nintegrated light spectroscopy with those of resolved colour-magnitude diagrams\nfrom the literature. As our main result, we propose that an ancient and an\nintermediate-age population coexist in M32, and that the balance between these\ntwo populations change between the nucleus and outside 1 effective radius in\nthe sense that the contribution from the intermediate population is larger at\nthe nuclear region. We retrieve a smaller signal of a young population at all\nradii whose origin is unclear and may be a contamination from horizontal-branch\nstars, such as the ones identified by Brown et al. in the nuclear region. We\ncompare our metallicity distribution function for a region 1 to 2 arcmin from\nthe centre to the one obtained with photometric data by Grillmair et al. Both\ndistributions are broad, but our spectroscopically derived distribution has a\nsignificant component with $[Z/Z_{\\sun}] \\leq -1$, which is not found by\nGrillmair et al." }, { "anchor": "Search for gamma-ray counterparts of newly discovered radio\n astrophysical sources: In this paper we study two newly discovered classes of radio sources: the\nhighly energetic, short-lived events, known as Fast Radio Bursts (FRBs), and a\nnew category of compact sources known as Fanaroff-Riley type 0 radio galaxies\n(FR0s). Due to a possible catastrophic event origin for the FRBs and a previous\ncorrelation found with an FR0 in the gamma ray spectrum, it is possible that\nthese radio sources could also emit high energy photons in the Fermi-LAT\nsatellite energy range (20 MeV - 300GeV). Here we present an exhaustive\ntime-dependent and spatial search of all up-to-date observed FRBs and FR0s,\nrespectively. We perform a likelihood analysis of the radio sources by modeling\nthe excess flux of gamma rays with a varying index power law function using\ndata from Fermi-LAT and the 4FGL catalog. Sources with test statistic greater\nthan 16 (corresponding to about 4{\\sigma}) were further analyzed including 2\nFRBs and 7 FR0s. No correlations with more than 5{\\sigma} were found after\ntaking into account nearby sources. Therefore, upper limits for all sources\nwere calculated", "positive": "Evaluating and Improving the Redshifts of z>2.2 Quasars: Quasar redshifts require the best possible precision and accuracy for a\nnumber of applications, such as setting the velocity scale for outflows as well\nas measuring small-scale quasar-quasar clustering. The most reliable redshift\nstandard in luminous quasars is arguably the narrow [OIII]\n$\\lambda\\lambda$4959,5007 emission line doublet in the rest-frame optical. We\nuse previously published [OIII] redshifts obtained using near-infrared spectra\nin a sample of 45 high-redshift (z > 2.2) quasars to evaluate redshift\nmeasurement techniques based on rest-frame ultraviolet spectra. At redshifts\nabove z = 2.2 the MgII $\\lambda$2798 emission line is not available in\nobserved-frame optical spectra, and the most prominent unblended and unabsorbed\nspectral feature available is usually CIV $\\lambda$1549. Peak and centroid\nmeasurements of the CIV profile are often blueshifted relative to the\nrest-frame of the quasar, which can significantly bias redshift determinations.\nWe show that redshift determinations for these high-redshift quasars are\nsignificantly correlated with the emission-line properties of CIV (i.e., the\nequivalent width, or EW, and the full width at half maximum, or FWHM) as well\nas the luminosity, which we take from the Sloan Digital Sky Survey Data Release\n7. We demonstrate that empirical corrections based on multiple regression\nanalyses yield significant improvements in both the precision and accuracy of\nthe redshifts of the most distant quasars and are required to establish\nconsistency with redshifts determined in more local quasars." }, { "anchor": "Was the Milky Way a chain galaxy? Using the IGIMF theory to constrain\n the thin-disk star formation history and mass: The observed present-day stellar mass function (PDMF) of the solar\nneighborhood is a mixture of stellar populations born in star-forming events\nthat occurred over the life-time of the thin disk of the Galaxy. Assuming stars\nform in embedded clusters which have stellar initial mass functions (IMFs)\nwhich depend on the metallicity and density of the star-forming gas clumps, the\nintegrated galaxy-wide IMF (IGIMF) can be calculated. The shape of the IGIMF\nthus depends on the SFR and metallicity. Here, the shape of the PDMF for stars\nmore massive than $1\\,M_\\odot$ in combination with the mass density in low-mass\nstars is used to constrain the current star-formation rate (SFR), the star\nformation history (SFH) and the current stellar plus remnant mass ($M_*$) in\nthe Galactic thin disk. This yields the current SFR, $\\dot{M}_*=\n4.1^{+3.1}_{-2.8}~M_\\odot$yr$^{-1}$, a declining SFH and\n$M_*=2.1^{+3.0}_{-1.5}\\times 10^{11}M_\\odot$, respectively, with a V-band\nstellar mass-to-light ratio of $M_*/L_V=2.79^{+0.48}_{-0.38}$.These values are\nconsistent with independent measurements. We also quantify the surface density\nof black holes and neutron stars in the Galactic thin disk. The invariant\ncanonical IMF can reproduce the PDMF of the Galaxy as well as the IGIMF, but in\nthe universal IMF framework it is not possible to constrain any of the above\nGalactic properties. Assuming the IGMF theory is the correct framework and in\ncombination with the vertical velocity dispersion data of stars, it follows\nthat the Milky Way would have appeared as a chain galaxy at high redshift.", "positive": "Tides or dark matter sub-halos: Which ones are more attractive?: Young tidal dwarf galaxies (TDGs) are observed in the tidal debris of\ngas-rich interacting galaxies. In contrast to what is generally assumed to be\nthe case for isolated dwarf galaxies, TDGs are not embedded in their own dark\nmatter (DM) sub-halo. Hence, they are more sensitive to stellar feedback and\ncould be disrupted on a short time-scale. Detailed numerical and observational\nstudies demonstrate that isolated DM-dominated dwarf galaxies can have\nlifetimes of more than 10 Gyr. For TDGs that evolve in a tidal field with\ncompressing accelerations equal to the gravitational acceleration within a DM\nsub-halo typical of an isolated dwarf galaxy, a similar survival time is\nexpected. The tidal acceleration profile depends on the virial mass of the host\ngalaxy and the distance between the TDG and its host. We analytically compare\nthe tidal compression to the gravitational acceleration due to either cuspy or\ncored DM sub-halos of various virial masses. For example, the tidal field at a\ndistance of 100 kpc to a host halo of 10^13 Msol can be as stabilizing as a\n10^9 Msol DM sub-halo. By linking the tidal field to the equivalent\ngravitational field of a DM sub-halo, we can use existing models of isolated\ndwarfs to estimate the survivability of TDGs. We show that part of the\nunexpectedly high dynamical masses inferred from observations of some TDGs can\nbe explained by tidal compression and hence TDGs require to contain less\nunobservable matter to understand their rotation curves." }, { "anchor": "The Effects of the Ionizing Radiation Background on Galaxy Evolution: We find that the amount and nature of the assumed ionizing background can\nstrongly affect galaxy formation and evolution. Galaxy evolution simulations\ntypically incorporate an ultraviolet background which falls off rapidly above\nz=3; e.g., that of Haardt & Madau (1996). However, this decline may be too\nsteep to fit the WMAP constraints on electron scattering optical depth or\nobservations of intermediate redshift (z ~ 2-4) Ly-alpha forest transmission.\nAs an alternative, we present simulations of the cosmological formation of\nindividual galaxies with UV backgrounds that decline more slowly at high\nredshift: both a simple intensity rescaling and the background recently derived\nby Faucher-Giguere (2009), which softens the spectrum at higher redshifts. We\nalso test an approximation of the X-ray background with a similar z-dependence.\nWe find for the test galaxies that an increase in either the intensity or\nhardness of ionizing radiation generically pushes star formation towards lower\nredshifts: although overall star formation in the simulation boxes is reduced\nby 10-25%, the galaxies show a factor of ~2 increase in the fraction of stars\nwithin a 30 kpc radius that are formed after z=1. Other effects include late\ngas inflows enhanced up to 30 times, stellar half-mass radii decreased by up to\n30%, central velocity dispersions increased up to 40%, and a strong reduction\nin substructure. The magnitude of the effects depends on the\nenvironmental/accretion properties of the particular galaxy.", "positive": "Stellar Populations in the Transition Region of Nuclear Star Cluster and\n Nuclear Stellar Disc: The Milky Way nuclear star cluster (NSC) is located within the nuclear\nstellar disc (NSD) in the Galactic centre. It is not fully understood if the\nformation and evolution of these two components are connected, and how they\ninfluence each other. We study the stellar populations in the transition region\nof NSC and NSD. We observed two $\\sim$4.3 pc$^2$ fields with the integral-field\nspectrograph KMOS (VLT), located at r$\\sim$20 pc (> 4 R$_e$) to the Galactic\nEast and West of the NSC. We extract and analyse medium-resolution stellar\nspectra of >200 stars per field. The data contain in total nine young star\ncandidates. We use stellar photometry to estimate the stellar masses, effective\ntemperatures, and spectral types of the young stars. The stars are consistent\nwith an age of 4-6 Myr, they may have formed inside the Quintuplet cluster, but\nwere dispersed in dynamical interactions. Most stars in the two fields are red\ngiant stars, and we measure their stellar metallicities [M/H] using full\nspectral fitting. We compare our [M/H] distributions to the NSC and NSD, using\ndata from the literature, and find that the overall metallicity decreases from\nthe central NSC, over the transition region, to the NSD. The steep decrease of\n[M/H] from the NSC to the region dominated by the NSD indicates that the two\ncomponents have distinct stellar populations and formation histories." }, { "anchor": "Probing the Galactic Halo with RR Lyrae Stars. II. The Substructures of\n the Milky Way: We identify substructures of the Galactic halo using 3,003 type $ab$ RR\nLyraes (RRab) with 6D position-velocity information from the SDSS, LAMOST, and\nGaia EDR3. Based on the information, we define the separation of any two of the\nstars in the integrals of motion space and identify substructures by utilizing\nthe friends-of-friends algorithm. We identify members belonging to several\nknown substructures: the Sagittarius stream, the Gaia-Enceladus-Sausage (GES),\nthe Sequoia, and the Helmi streams. In addition to these known substructures,\nthere are three other substructures possibly associated with globular clusters\nNGC 5272, NGC 6656, and NGC 5024, respectively. Finally, we also find three\nremaining unknown substructures and one of them has large angular momentum and\na mean metallicity $\\rm -2.13\\,dex$ which may be a new substructure. As for\nGES, we find that it accounts for a large part of substructures in the inner\nhalo and the range of apocenter distance is from 10 to $34\\,\\rm kpc$, which\nsuggests that the GES is mainly distributed in the inner halo. The near\none-third proportion of the GES and the peak value $20\\,\\rm kpc$ of the\napocenter distances suggest that GES could account for the break in the density\nprofile of the Galactic halo at Galactocentric distance ${\\sim}20-25\\,\\rm kpc$.\nThe similarity of comparing the kinematic properties of Gaia-Enceladus-Sausage\nwith the Hercules-Aquila Cloud and Virgo Overdensity suggests that the three\nsubstructures may have similar origins.", "positive": "Galaxy Structural Analysis with the Curvature of the Brightness Profile: In this work we introduce the curvature of a galaxy brightness profile to\nidentify its structural subcomponents in a non-parametrically fashion. Bulges,\nbars, disks, lens, rings and spiral arms are key to understand the formation\nand evolution path the galaxy undertook. Identifying them is also crucial for\nmorphological classification of galaxies. We measure and analyse in detail the\ncurvature of $14$ galaxies with varied morphology. High (low) steepness\nprofiles show high (low) curvature measures. Transitions between components are\nidentified as local peaks oscillations in the values of the curvature. We\nidentify patterns that characterise bulges (pseudo or classic), disks, bars and\nrings. This method can be automated to identify galaxy components in large\ndatasets or to provide a reliable starting point for traditional multicomponent\nmodelling of galaxy light distribution." }, { "anchor": "Identifying Contributions to the Stellar Halo from Accreted, Kicked-Out,\n and In Situ Populations: [Abridged] We present a medium-resolution spectroscopic survey of late-type\ngiant stars at mid-Galactic latitudes of (30$^{\\circ}<|b|<60^{\\circ}$),\ndesigned to probe the properties of this population to distances of $\\sim$9\nkpc. Because M giants are generally metal-rich and we have limited\ncontamination from thin disk stars by the latitude selection, most of the stars\nin the survey are expected to be members of the thick disk\n($<$[Fe/H]$>\\sim$-0.6) with some contribution from the metal-rich component of\nthe nearby halo.\n Here we report first results for 1799 stars. The distribution of radial\nvelocity (RV) as a function of l for these stars shows (1) the expected thick\ndisk population and (2) local metal-rich halo stars moving at high speeds\nrelative to the disk, that in some cases form distinct sequences in RV-$l$\nspace. High-resolution echelle spectra taken for 34 of these \"RV outliers\"\nreveal the following patterns across the [Ti/Fe]-[Fe/H] plane: seventeen of the\nstars have abundances reminiscent of the populations present in dwarf\nsatellites of the Milky Way; eight have abundances coincident with those of the\nGalactic disk and more metal-rich halo; and nine of the stars fall on the locus\ndefined by the majority of stars in the halo. The chemical abundance trends of\nthe RV outliers suggest that this sample consists predominantly of stars\naccreted from infalling dwarf galaxies. A smaller fraction of stars in the RV\noutlier sample may have been formed in the inner Galaxy and subsequently kicked\nto higher eccentricity orbits, but the sample is not large enough to\ndistinguish conclusively between this interpretation and the alternative that\nthese stars represent the tail of the velocity distribution of the thick disk.\nOur data do not rule out the possibility that a minority of the sample could\nhave formed from gas {\\it in situ} on their current orbits.", "positive": "The pc-scale radio structure of MIR-observed radio galaxies: We investigated the relationship between the accretion process and jet\nproperties by ultilizing the VLBA and mid-infrared (MIR) data for a sample of\n45 3CRR radio galaxies selected with a flux density at 178 MHz $>16.4$ Jy, 5\nGHz VLA core flux density $\\geq$ 7 mJy, and MIR observations. The pc-scale\nradio structure at 5 GHz are presented by using our VLBA observations for 21\nsources in February, 2016, the analysis on the archival data for 16 objects,\nand directly taking the measurements for 8 radio galaxies available in\nliteratures. The accretion mode is constrained from the Eddington ratio with a\ndividing value of 0.01, which is estimated from the MIR-based bolometric\nluminosity and the black hole masses. While most FRII radio galaxies have\nhigher Eddington ratio than FRIs, we found that there is indeed no single\ncorrespondence between the FR morphology and accretion mode with eight FRIIs at\nlow accretion and two FRIs at high accretion rate. There is a significant\ncorrelation between the VLBA core luminosity at 5 GHz and the Eddington ratio.\nVarious morphologies are found in our sample, including core only, single-sided\ncore-jet, and two-sided core-jet structures. We found that the higher accretion\nrate may be more likely related with the core-jet structure, thus more extended\njet. These results imply that the higher accretion rates are likely able to\nproduce more powerful jets. There is a strong correlation between the MIR\nluminosity at 15 $\\mu$m and VLBA 5 GHz core luminosity, in favour of the tight\nrelation between the accretion disk and jets. In our sample, the core\nbrightness temperature ranges from $10^{9}$ to $10^{13.38}$ K with a median\nvalue of $10^{11.09}$ K indicating that systematically the beaming effect may\nnot be significant...." }, { "anchor": "The AKARI Deep Field South: Pushing to High Redshift: The AKARI Deep Field South (ADF-S) is a large extragalactic survey field that\nis covered by multiple instruments, from optical to far-IR and radio. I\nsummarise recent results in this and related fields prompted by the release of\nthe Herschel far-IR/submm images, including studies of cold dust in nearby\ngalaxies, the identification of strongly lensed distant galaxies, and the use\nof colour selection to find candidate very high redshift sources. I conclude\nthat the potential for significant new results from the ADF-S is very great.\nThe addition of new wavelength bands in the future, eg. from Euclid, SKA, ALMA\nand elsewhere, will boost the importance of this field still further.", "positive": "WZ Sge: an eclipsing cataclysmic variable evolving towards the period\n minimum: We present the photometric results of the eclipsing cataclysmic variable (CV)\nWZ Sge near the period minimum ($P_{min}$). Eight new mid-eclipse times were\ndetermined and the orbital ephemeris was updated. Our result shows that the\norbital period of WZ Sge is decreasing at a rate of\n$\\dot{P}=-2.72(\\pm0.23)\\times{10^{-13}}\\,s s^{-1}$. This secular decrease,\ncoupled with previous detection of its donor, suggest that WZ Sge is a\npre-bounce system. Further analysis indicates that the observed period decrease\nrate is about $1.53$ times higher than pure gravitational radiation (GR)\ndriving. We constructed the evolutionary track of WZ Sge, which predicts that\n$P_{min}$ of WZ Sge is $\\sim77.98 (\\pm0.90)$ min. If the orbital period\ndecreases at the current rate, WZ Sge will evolve past its $P_{min}$ after\n$\\sim25.3$ Myr. Based on the period evolution equation we find\n$\\dot{M}_{2}\\simeq4.04(\\pm0.10)\\times10^{-11}M_{\\odot}yr^{-1}$, which is\ncompatible with the current concept of CV evolution at ultrashort orbital\nperiods." }, { "anchor": "Radiative effects during the assembly of direct collapse black holes: We perform a post-processing radiative feedback analysis on a 3D ab initio\ncosmological simulation of an atomic cooling halo under the direct collapse\nblack hole (DCBH) scenario. We maintain the spatial resolution of the\nsimulation by incorporating native ray-tracing on unstructured mesh data,\nincluding Monte Carlo Lyman-alpha (Ly{\\alpha}) radiative transfer. DCBHs are\nborn in gas-rich, metal-poor environments with the possibility of Compton-thick\nconditions, $N_H \\gtrsim 10^{24} {\\rm cm}^{-2}$. Therefore, the surrounding gas\nis capable of experiencing the full impact of the bottled-up radiation\npressure. In particular, we find that multiple scattering of Ly{\\alpha} photons\nprovides an important source of mechanical feedback after the gas in the\nsub-parsec region becomes partially ionized, avoiding the bottleneck of\ndestruction via the two-photon emission mechanism. We provide detailed\ndiscussion of the simulation environment, expansion of the ionization front,\nemission and escape of Ly{\\alpha} radiation, and Compton scattering. A sink\nparticle prescription allows us to extract approximate limits on the\npost-formation evolution of the radiative feedback. Fully coupled Ly{\\alpha}\nradiation hydrodynamics will be crucial to consider in future DCBH simulations.", "positive": "Multiply lensed star forming clumps in the A521-sys1 galaxy at redshift\n 1: We study the population of star-forming clumps in A521-sys1, a $\\rm z=1.04$\nsystem gravitationally lensed by the foreground ($\\rm z=0.25$) cluster Abell\n0521. The galaxy presents one complete counter--image with a mean magnification\nof $\\rm \\mu\\sim4$ and a wide arc containing two partial images of A521-sys1\nwith magnifications reaching $\\rm \\mu>20$, allowing the investigations of\nclumps down to scales of $\\rm R_{eff}<50$ pc. We identify 18 unique clumps with\na total of 45 multiple images. Intrinsic sizes and UV magnitudes reveal clumps\nwith elevated surface brightnesses, comparable to similar systems at redshifts\n$\\rm z\\gtrsim1.0$. Such clumps account for $\\sim40\\%$ of the galaxy UV\nluminosity, implying that a significant fraction of the recent star-formation\nactivity is taking place there. Clump masses range from $\\rm 10^6\\ M_\\odot$ to\n$\\rm 10^9\\ M_\\odot$ and sizes from tens to hundreds of parsec, resulting in\nmass surface densities from $10$ to $\\rm 10^3\\ M_\\odot\\ pc^{-2}$, with a median\nof $\\rm \\sim10^2\\ M_\\odot\\ pc^{-2}$. These properties suggest that we detect\nstar formation taking place across a wide range of scale, from cluster\naggregates to giant star-forming complexes. We find ages of less than $100$\nMyr, consistent with clumps being observed close to their natal region. The\nlack of galactocentric trends with mass, mass density, or age and the lack of\nold migrated clumps can be explained either by dissolution of clumps after few\n$\\sim100$ Myr or by stellar evolution making them fall below the detectability\nlimits of our data." }, { "anchor": "Connecting Galactic Outflows and Star Formation: Inferences from H-alpha\n Maps and Absorption Line Spectroscopy at 1 < z < 1.5: We investigate the connection between galactic outflows and star formation\nusing two independent data sets covering a sample of 22 galaxies between $1\n\\lesssim z \\lesssim 1.5$. The HST WFC3/G141 grism provides low spectral\nresolution, high spatial resolution spectroscopy yielding H$\\alpha$ emission\nline maps from which we measure the spatial extent and strength of star\nformation. In the rest-frame near-UV, Keck/DEIMOS observes Fe II and Mg II\ninterstellar absorption lines, which provide constraints on the intensity and\nvelocity of the outflows. We compare outflow properties from individual and\ncomposite spectra with the star formation rate (SFR) and SFR surface density\n(SigmaSFR), as well as the stellar mass and specific star formation rate\n(sSFR). The Fe II and Mg II equivalent widths (EWs) increase with both SFR and\nSigmaSFR at $\\gtrsim 3\\sigma$ significance, while the composite spectra show\nlarger Fe II EWs and outflow velocities in galaxies with higher SFR, SigmaSFR,\nand sSFR. Absorption line profiles of the composite spectra further indicate\nthat the differences between subsamples are driven by outflows rather than the\nISM. While these results are consistent with those of previous studies, the use\nof H$\\alpha$ images makes them the most direct test of the relationship between\nstar formation and outflows at $z>1$ to date. Future facilities such as the\nJames Webb Space Telescope and the upcoming Extremely Large Telescopes will\nextend these direct, H$\\alpha$-based studies to lower masses and star formation\nrates, probing galactic feedback across orders of magnitude in galaxy\nproperties and augmenting the correlations we find here.", "positive": "Search for Stellar Streams Based on Data from the RAVE5 and Gaia TGAS\n Catalogues: We have analyzed the space velocities of stars with the proper motions and\ntrigonometric parallaxes from the Gaia TGAS catalogue in combination with the\nline-of-sight velocities from the RAVE5 catalogue. In the (V,\\sqrt{U^2+2V^2})\nvelocity plane we have identified three clumps, BB17-1, BB17-2, and BB17-3, in\nthe region of large velocities (V<-150 km/s). The stars of the BB17-1 and\nBB17-2 clumps are associated with the kinematic groups VelHel-6 and VelHel-7\ndetected previously by Helmi et al. We give the greatest attention to the\nBB17-3 clump. The latter is shown to be most closely linked with the debris of\nthe globular cluster \\omega Cen. In the BB17-3 clump we have identified 28\nstars with a low velocity dispersion with respect to the center of their\ndistribution. All these stars have very close individual age estimates: \\log\nt\\approx 10. The distribution of metallicity indices in this sample is typical\nfor the stars of the globular cluster \\omega Cen. In our opinion, the BB17-3\nclump can be described as a homogeneous stream in the debris of the cluster\n\\omega Cen." }, { "anchor": "HD/H$_2$ ratio in the diffuse interstellar medium: We present a semi-analytical description of the relative HD/H2 abundance in\nthe diffuse interstellar medium. We found three asymptotics of the relative\nHD/H$_2$ abundance for different parts of the medium and their dependence on\nthe physical parameters, namely, number density, intensity of the ultraviolet\nfield, cosmic-ray ionization rate and metallicity. Our calculations are in a\ngood agreement with the full network calculations using Meudon PDR code. We\nfound that in the case of low metallicity and/or higher cosmic ray ionization\nrate, HD formation rate is significantly enhanced, HD/H2 ratio increases, and\nthe DI/HD transition occurs at a lower penetration depth of UV radiation than\nthe HI/H$_2$ transition. This can explain the observed difference in the\nHD/H$_2$ abundance between the local and high-redshift measurements.", "positive": "Observed versus Simulated Halo c-Mvir Relations: The concentration - virial mass relation is a well-defined trend that\nreflects the formation of structure in an expanding Universe. Numerical\nsimulations reveal a marked correlation that depends on the collapse time of\ndark matter halos and their subsequent assembly history. However, observational\nconstraints are mostly limited to the massive end via X-ray emission of the hot\ndiffuse gas in clusters. An alternative approach, based on gravitational\nlensing over galaxy scales, revealed an intriguingly high concentration at\nMilky Way-sized halos. This letter focuses on the robustness of these results\nby adopting a bootstrapping approach that combines stellar and lensing mass\nprofiles. We also apply the identical methodology to simulated halos from EAGLE\nto assess any systematic. We bypass several shortcomings of ensemble type lens\nreconstruction and conclude that the mismatch between observed and simulated\nconcentration-to-virial-mass relations are robust, and need to be explained\neither invoking a lensing-related sample selection bias, or a careful\ninvestigation of the evolution of concentration with assembly history. For\nreference, at a halo mass of $10^{12} M_\\odot$, the concentration of observed\nlenses is $c_{12}\\sim 40\\pm 5$, whereas simulations give $c_{12}\\sim 15\\pm1$." }, { "anchor": "Widespread Galactic CF+ absorption: detection toward W49 with the\n Plateau de Bure Interferometer: To study the usefulness of \\CFP\\ as a tracer of the regions where C\\p\\ and\n\\HH\\ coexist in the interstellar medium. We used the Plateau de Bure\nInterferometer to synthesize \\CFP\\ J=1-0 absorption at 102.6 GHz toward the\ncore of the distant HII region W49N at l = 43.2\\degr, b=0.0\\degr, and we\nmodeled the fluorine chemistry in diffuse/translucent molecular gas. We\ndetected \\CFP\\ absorption over a broad range of velocity showing that \\CFP\\ is\nwidespread in the \\HH-bearing Galactic disk gas. Originally detected in dense\ngas in the Orion Bar and Horsehead PDR, \\CFP\\ was subsequently detected in\nabsorption from diffuse and translucent clouds seen toward \\bll\\ and 3C111.\nHere we showed that \\CFP\\ is distributed throughout the diffuse and translucent\nmolecular disk gas with N(\\CFP)/N(\\HH) $= 1.5-2.0\\times10^{-10}$, increasing to\nN(\\CFP)/N(\\HH) $= 3.5\\times10^{-10}$ in one cloud at 39 \\kms\\ having higher\nN(\\HH) $\\approx 3\\times10^{21}\\pcc$. Models of the fluorine chemistry reproduce\nthe observed column densities and relative abundance of HF, from which \\CFP\\\nforms, but generally overpredict the the column density of \\CFP\\ by factors of\n1.4-4. We show that a free space photodissociation rate $\\Gamma \\ga\n10^{-9}\\ps$, comparable to that of CH, might account for much of the\ndiscrepancy but a recent calculation finds a value about ten times smaller. In\nthe heavily blended and kinematically complex spectra seen toward W49, \\CFP\\\nabsorption primarily traces the peaks of the \\HH\\ distribution.", "positive": "Effects of Grain Magnetic Properties and Grain Growth on Synthetic Dust\n Polarization of MHD Simulations in Protostellar Environments: Thermal dust polarization is a powerful tool to probe magnetic fields\n($\\textbf{B}$) and grain properties. However, a systematic study of the\ndependence of dust polarization on grain properties in protostellar\nenvironments is not yet available. In this paper, we post-process a non-ideal\nMHD simulation of a collapsing protostellar core with our updated POLARIS code\nto study in detail the effects of iron inclusions and grain growth on thermal\ndust polarization. We found that superparamagnetic (SPM) grains can produce\nhigh polarization degree of $p \\sim 10-40\\%$ beyond $\\sim 500$ au from the\nprotostar because of their efficient alignment by magnetically enhanced\nRadiative Torque mechanism. The magnetic field tangling by turbulence in the\nenvelope causes the decrease in $p$ with increasing emission intensity $I$ as\n$p\\propto I^{\\alpha}$ with the slope $\\alpha \\sim -0.3$. But within 500 au, SPM\ngrains tend to have inefficient internal alignment (IA) and be aligned with\n$\\textbf{B}$ by RATs only, producing lower $p \\sim 1\\%$ and a steeper slope of\n$\\alpha \\sim -0.6$. For paramagnetic (PM) grains, the alignment loss of grains\nabove $1\\mu m$ in the inner $\\sim 200$ au produces $p << 1\\%$ and the\npolarization hole with $\\alpha \\sim -0.9$. Grain growth can increase $p$ in the\nenvelope for SPM grains, but cause stronger depolarization for SPM grains in\nthe inner $\\sim 500$ au and for PM grains in the entire protostellar core.\nFinally, we found the increase of polarization angle dispersion function $S$\nwith iron inclusions and grain growth, implying the dependence of B-field\nstrength measured using the DCF technique on grain alignment and grain\nproperties." }, { "anchor": "A Precision Multi-Band Two-Epoch Photometric Catalog of 44 Million\n Sources in the Northern Sky from Combination of the USNO-B and Sloan Digital\n Sky Survey Catalogs: A key science driver for the next generation of wide-field optical and radio\nsurveys is the exploration of the time variable sky. These surveys will have\nunprecedented sensitivity and areal coverage, but will be limited in their\nability to detect variability on time scales longer than the lifetime of the\nsurveys. We present a new precision, multi-epoch photometric catalog that spans\n60 years by combining the USNO-B and SDSS Data Release 9 catalogs. We\nrecalibrate the photometry of the original USNO-B catalog and create a catalog\nwith two epochs of photometry in up to five different bands for 43,647,887\noptical point sources that lie in the DR9 footprint of the northern sky. The\nrecalibrated objects span a magnitude range 14 < m < 20 and are accurate to\n$\\approx$ 0.1 mag. We minimize the presence of spurious objects and those with\ninaccurate magnitudes by identifying and removing several sources of systematic\nerrors in the two originating catalogs, with a focus on spurious objects that\nexhibit large apparent magnitude variations. After accounting for these\neffects, we find $\\approx$ 250,000 stars and quasars that show significant (>\n4$\\sigma$) changes in brightness between the USNO-B and SDSS DR9 epochs. We\ndiscuss the historical value of the catalog and its application to the study of\nlong time-scale, large amplitude variable stars and quasars.", "positive": "Absorption spectra of electrified hydrogen molecules: Molecular hydrogen normally has only weak, quadrupole transitions between its\nrovibrational states, but in a static electric field it acquires a dipole\nmoment and a set of allowed transitions. Here we use published ab initio\ncalculations of the static electrical response tensors of the H2 molecule to\nconstruct the perturbed rovibrational eigensystem and its ground state\nabsorptions. We restrict attention to two simple field configurations that are\nrelevant to condensed hydrogen molecules in the interstellar medium: a uniform\nelectric field, and the field of a point-like charge. The energy eigenstates\nare mixtures of vibrational and angular momentum eigenstates so there are many\ntransitions that satisfy the dipole selection rules. We find that mixing is\nstrongest amongst the states with high vibrational excitation, leading to\nhundreds of absorption lines across the optical and near infrared. These\nspectra are very different to that of the field-free molecule, so if they\nappeared in astronomical data they would be difficult to assign. Furthermore in\na condensed environment the excited states likely have short lifetimes to\ninternal conversion, giving the absorption lines a diffuse appearance. We\ntherefore suggest electrified H2 as a possible carrier of the Diffuse\nInterstellar Bands (DIBs). We further argue that in principle it may be\npossible to account for all of the DIBs with this one carrier. However, despite\nelectrification the transitions are not very strong and a large column of\ncondensed H2 would be required, making it difficult to reconcile this\npossibility with our current understanding of the ISM." }, { "anchor": "Gas around galaxy haloes - III: hydrogen absorption signatures around\n galaxies and QSOs in the Sherwood simulation suite: Modern theories of galaxy formation predict that galaxies impact on their\ngaseous surroundings, playing the fundamental role of regulating the amount of\ngas converted into stars. While star-forming galaxies are believed to provide\nfeedback through galactic winds, Quasi-Stellar Objects (QSOs) are believed\ninstead to provide feedback through the heat generated by accretion onto a\ncentral supermassive black hole. A quantitative difference in the impact of\nfeedback on the gaseous environments of star-forming galaxies and QSOs has not\nbeen established through direct observations. Using the Sherwood cosmological\nsimulations, we demonstrate that measurements of neutral hydrogen in the\nvicinity of star-forming galaxies and QSOs during the era of peak galaxy\nformation show excess LyA absorption extending up to comoving radii of about\n150 kpc for star-forming galaxies and 300 - 700 kpc for QSOs. Simulations\nincluding supernovae-driven winds with the wind velocity scaling like the\nescape velocity of the halo account for the absorption around star-forming\ngalaxies but not QSOs.", "positive": "The Kinematic Distance to NGC 6309: We report an updated value for the distance to the planetary nebula NGC 6309\n(the Box Nebula). The distance is found through two Kinematic Distance Methods\n(KDMs): the system of two equations reported in Zhu et al. 2013 and the Monte\nCarlo method reported by Wenger et al. 2018. We find the kinematic distance to\nNGC 6309 to be 4.1 kpc with an upper uncertainty of +0.29 kpc and a lower\nuncertainty of -0.38 kpc. We also calculate the distance to Cassiopeia A with\nthe two KDMs and compare to the value reported by Reed et al 1995. The Zhu et\nal. method and Wenger et al. method yield a value within thirty percent and\ntwenty percent of the Reed et al. method, respectively. The value reported by\nReed et al 1995 was contained within the error bounds produced by the Wenger et\nal. method. The distance measurement to Cassiopeia A suggests that both KDMs,\nwhile imperfect, are moderately accurate methods for determining the distance\nto NGC objects in the plane of the Milky Way." }, { "anchor": "A robust mass estimator for dark matter subhalo perturbations in strong\n gravitational lenses: A few dark matter substructures have recently been detected in strong\ngravitational lenses though their perturbations of highly magnified images. We\nderive a characteristic scale for lensing perturbations and show that this is\nsignificantly larger than the perturber's Einstein radius. We show that the\nperturber's projected mass enclosed within this radius, scaled by the log-slope\nof the host galaxy's density profile, can be robustly inferred even if the\ninferred density profile and tidal radius of the perturber are biased. We\ndemonstrate the validity of our analytic derivation by using several\ngravitational lens simulations where the tidal radii and the inner log-slopes\nof the density profile of the perturbing subhalo are allowed to vary. By\nmodeling these simulated data we find that our mass estimator, which we call\nthe effective subhalo lensing mass, is accurate to within about 10\\% or smaller\nin each case, whereas the inferred total subhalo mass can potentially be biased\nby nearly an order of magnitude. We therefore recommend that the effective\nsubhalo lensing mass be reported in future lensing reconstructions, as this\nwill allow for a more accurate comparison with the results of dark matter\nsimulations.", "positive": "SNIa Host Galaxy Properties and the Dust Extinction Distribution: Supernovae Type Ia display a complex relation with their host galaxies. An\nimportant prior to the fit of the supernovae's lightcurve is the distribution\nof host galaxy extinction values that can be encountered. The SDSS-SN project\nhas published light curve fits using both MLCS2k2 and SALT2. We use the former\nfits extinction parameter ($A_V$) to map this distribution of extinction\nvalues.\n We explore the dependence of this distribution on four observables; the\ninclination of the host galaxy disk, radial position of the supernova, redshift\nof the supernova and host, and the level of star-formation in the host galaxy.\nThe distribution of $A_V$ values encountered by supernovae is typically\ncharacterised by: $\\rm N_0 ~ e^{-A_V/\\tau}$, with $\\tau$= 0.4 or 0.33.\n We find that the inclination correction using an infinitely thin disk for the\nSNIa is sufficient, resulting in similar exponential $A_V$ distributions for\nhigh- and low-inclination disks. The $A_V$ distribution also depends on the\nradial position in the disk, consistent with previous results on the\ntransparency of spiral disks. The distribution of $A_V$ values narrows with\nincreased star-formation, possibly due to the destruction or dispersion of the\ndusty ISM by stellar winds prior to the ignition of the supernova.\n In future supernova searches, certainly the inclination of the host galaxy\ndisk, should be considered in the construction of the \\av \\ prior with\n$\\tau=0.4/cos(i)$ as the most likely prior in each individual host galaxy's\ncase." }, { "anchor": "What shapes a galaxy? - Unraveling the role of mass, environment and\n star formation in forming galactic structure: We investigate the dependence of galaxy structure on a variety of galactic\nand environmental parameters for ~500,000 galaxies at z<0.2, taken from the\nSloan Digital Sky Survey data release 7 (SDSS-DR7). We utilise bulge-to-total\nstellar mass ratio, (B/T)_*, as the primary indicator of galactic structure,\nwhich circumvents issues of morphological dependence on waveband. We rank\ngalaxy and environmental parameters in terms of how predictive they are of\ngalaxy structure, using an artificial neural network approach. We find that\ndistance from the star forming main sequence (Delta_SFR), followed by stellar\nmass (M_*), are the most closely connected parameters to (B/T)_*, and are\nsignificantly more predictive of galaxy structure than global star formation\nrate (SFR), or any environmental metric considered (for both central and\nsatellite galaxies). Additionally, we make a detailed comparison to the\nIllustris hydrodynamical simulation and the LGalaxies semi-analytic model. In\nboth simulations, we find a significant lack of bulge-dominated galaxies at a\nfixed stellar mass, compared to the SDSS. This result highlights a potentially\nserious problem in contemporary models of galaxy evolution.", "positive": "Updated radio $\u03a3-D$ relation for Galactic supernova remnants -- II: In this paper we present the updated empirical radio\nsurface-brightness-to-diameter ($\\Sigma$--$D$) relation for Galactic supernova\nremnants (SNRs) calibrated using $110$ SNRs with reliable distances. We apply\northogonal fitting procedure and kernel density smoothing in $\\Sigma-D$ plane\nand compare the results with the latest theoretical $\\Sigma-D$ relations\nderived from simulations of radio evolution of SNRs. We argue that the best\nagreement between the empirical and simulated $\\Sigma-D$ relations is achieved\nif the mixed-morphology SNRs and SNRs of both, low brightness and small\ndiameter, are filtered out from the calibration sample. The distances to $5$\nnewly discovered remnants and $27$ new candidates for shell SNRs are estimated\nfrom our full and filtered calibration samples." }, { "anchor": "Frequency-resolved lags in UV/optical continuum reverberation mapping: In recent years, continuum reverberation mapping involving high cadence\nUV/optical monitoring campaigns of nearby Active Galactic Nuclei has been used\nto infer the size of their accretion disks. One of the main results from these\ncampaigns has been that in many cases the accretion disks appear too large, by\na factor of 2 - 3, compared to standard models. Part of this may be due to\ndiffuse continuum emission from the broad line region (BLR), which is indicated\nby excess lags around the Balmer jump. Standard cross correlation lag analysis\ntechniques are usually used to just recover the peak or centroid lag and can\nnot easily distinguish between reprocessing from the disk and BLR. However,\nfrequency-resolved lag analysis, where the lag is determined at each Fourier\nfrequency, has the potential to separate out reprocessing on different size\nscales. Here we present simulations to demonstrate the potential of this method\nand then apply a maximum likelihood approach to determine frequency-resolved\nlags in NGC 5548. We find that the lags in NGC 5548 generally decrease smoothly\nwith increasing frequency, and are not easily described by accretion disk\nreprocessing alone. The standard cross correlation lags are consistent with\nlags at frequencies lower than 0.1 per day, indicating they are dominated from\nreprocessing at size scales greater than about 10 light days. A combination of\na more distant reprocessor, consistent with the BLR, along with a\nstandard-sized accretion disk is more consistent with the observed lags than a\nlarger disk alone.", "positive": "The disk-outflow system around the rare young O-type protostar W42-MME: We present line and continuum observations (resolution ~0.3\"-3.5\") made with\nthe Atacama Large Millimeter/submillimeter Array (ALMA), Submillimeter Array,\nand Very Large Array of a young O-type protostar W42-MME (mass: 19-4 Msun). The\nALMA 1.35 mm continuum map (resolution ~1\") shows that W42-MME is embedded in\none of the cores (i.e., MM1) located within a thermally supercritical\nfilament-like feature (extent ~0.15 pc) containing three cores (mass ~1-4.4\nMsun). Several dense/hot gas tracers are detected toward MM1, suggesting the\npresence of a hot molecular core with the gas temperature of ~38-220~K. The\nALMA 865 micron continuum map (resolution ~0.3\") reveals at least five\ncontinuum sources/peaks (\"A-E\") within a dusty envelope (extent ~9000 AU)\ntoward MM1, where shocks are traced in the SiO(8-7) emission. The source \"A\"\nassociated with W42-MME is seen almost at the center of the dusty envelope, and\nis surrounded by other continuum peaks. The ALMA CO(3-2) and SiO(8-7) line\nobservations show the bipolar outflow extended below 10000 AU, which is driven\nby the source \"A\". The ALMA data hint the episodic ejections from W42-MME. A\ndisk-like feature (extent ~2000 AU; mass ~1 Msun) with velocity gradients is\ninvestigated in the source \"A\" (dynamical mass ~9 Msun) using the ALMA H13CO+\nemission, and is perpendicular to the CO outflow. A small-scale feature (below\n3000 AU) probably heated by UV radiation from the O-type star is also\ninvestigated toward the source \"A\". Overall, W42-MME appears to gain mass from\nits disk and the dusty envelope." }, { "anchor": "The Great Observatories All-Sky LIRG Survey: Herschel Image Atlas and\n Aperture Photometry: Far-infrared (FIR) images and photometry are presented for 201 Luminous and\nUltraluminous Infrared Galaxies [LIRGs: log$(L_{\\rm IR}/L_\\odot) = 11.00 -\n11.99$, ULIRGs: log$(L_{\\rm IR}/L_\\odot) = 12.00 - 12.99$], in the Great\nObservatories All-Sky LIRG Survey (GOALS) based on observations with the\n$Herschel$ $Space$ $Observatory$ Photodetector Array Camera and Spectrometer\n(PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) instruments.\nThe image atlas displays each GOALS target in the three PACS bands (70, 100,\nand 160 $\\mu$m) and the three SPIRE bands (250, 350, and 500 $\\mu$m), optimized\nto reveal structures at both high and low surface brightness levels, with\nimages scaled to simplify comparison of structures in the same physical areas\nof $\\sim$$100\\times100$ kpc$^2$. Flux densities of companion galaxies in\nmerging systems are provided where possible, depending on their angular\nseparation and the spatial resolution in each passband, along with integrated\nsystem fluxes (sum of components). This dataset constitutes the imaging and\nphotometric component of the GOALS Herschel OT1 observing program, and is\ncomplementary to atlases presented for the Hubble Space Telescope (Evans et al.\n2017, in prep.), Spitzer Space Telescope (Mazzarella et al. 2017, in prep.),\nand Chandra X-ray Observatory (Iwasawa et al. 2011, 2017, in prep.).\nCollectively these data will enable a wide range of detailed studies of AGN and\nstarburst activity within the most luminous infrared galaxies in the local\nUniverse.", "positive": "10C continued: a deeper radio survey at 15.7 GHz: We present deep 15.7-GHz observations made with the Arcminute Microkelvin\nImager Large Array in two fields previously observed as part of the Tenth\nCambridge (10C) survey. These observations allow the source counts to be\ncalculated down to 0.1 mJy, a factor of five deeper than achieved by the 10C\nsurvey. The new source counts are consistent with the extrapolated fit to the\n10C source count, and display no evidence for either steepening or flattening\nof the counts. There is thus no evidence for the emergence of a significant new\npopulation of sources (e.g. starforming) at 15.7 GHz flux densities above 0.1\nmJy, the flux density level at which we expect starforming galaxies to begin to\ncontribute. Comparisons with the de Zotti et al. model and the SKADS Simulated\nSky show that they both underestimate the observed number of sources by a\nfactor of two at this flux density level. We suggest that this is due to the\nflat-spectrum cores of radio galaxies contributing more significantly to the\ncounts than predicted by the models." }, { "anchor": "Pulsar Wind Nebulae: On their growing diversity and association with\n highly magnetized neutron stars: The 1968 discovery of the Crab and Vela pulsars in their respective supernova\nremnants (SNRs) confirmed Baade and Zwicky's 1934 prediction that supernovae\nform neutron stars. Observations of Pulsar Wind Nebulae (PWNe), particularly\nwith the Chandra X-ray Observatory, have in the past decade opened a new window\nto focus on the neutron stars' relativistic winds, study their interaction with\ntheir hosting SNRs, and find previously missed pulsars. While the Crab has been\nthought for decades to represent the prototype of PWNe, we now know of\ndifferent classes of neutron stars and PWNe whose properties differ from the\nCrab. In this talk, I review the current status of neutron stars/PWNe-SNRs\nassociations, and highlight the growing diversity of PWNe with an X-ray eye on\ntheir association with highly magnetized neutron stars. I conclude with an\noutlook to future high-energy studies.", "positive": "Matryoshka Holes: Nested Emission Rings in the Transitional Disk Oph IRS\n 48: The processes that form transition disks - disks with depleted inner regions\n- are not well understood; possible scenarios include planet formation, grain\ngrowth and photoevaporation. Disks with spatially resolved dust holes are rare,\nbut, in general, even less is known about the gas structure. The disk\nsurrounding A0 star Oph IRS 48 in the nearby Rho Ophiuchus region has a 30 AU\nradius hole previously detected in the 18.7 micron dust continuum and in warm\nCO in the 5 micron fundamental ro-vibrational band. We present here\nSubmillimeter Array 880 micron continuum imaging resolving an inner hole.\nHowever, the radius of the hole in the millimeter dust is only 13 AU,\nsignificantly smaller than measured at other wavelengths. The nesting structure\nof the disk is counter-intuitive, with increasingly large radii rings of\nemission seen in the millimeter dust (12.9 +1.7/-3.4 AU), 5 micron CO (30 AU)\nand 18.7 micron dust (peaking at 55 AU). We discuss possible explanations for\nthis structure, including self-shadowing that cools the disk surface layers,\nphotodissociation of CO, and photoevaporation. However, understanding this\nunusual disk within the stringent multi-wavelength spatial constraints will\nrequire further observations to search for cold atomic and molecular gas." }, { "anchor": "Evolution of Dust-Obscured Star Formation and Gas to z=2.2 from HiZELS: We investigate the far-infrared properties of galaxies selected via deep,\nnarrow-band imaging of the H$\\alpha$ emission line in four redshift slices from\n$z=0.40$--$2.23$ over $\\sim 1$deg$^2$ as part of the High-redshift Emission\nLine Survey (HiZELS). We use a stacking approach in the Herschel PACS/SPIRE\nbands, along with $850\\,\\mu$m imaging from SCUBA-2 to study the evolution of\nthe dust properties of H$\\alpha$-emitters selected above an evolving\ncharacteristic luminosity threshold, $0.2L^\\star_{{\\rm H}\\alpha}(z)$. We\ninvestigate the relationship between the dust temperatures and the far-infrared\nluminosities of our stacked samples, finding that H$\\alpha$-selection\nidentifies cold, low-$L_{\\rm IR}$ galaxies ($T_{\\rm dust}\\sim 14$k;\n$\\log[L_{\\rm IR}/{\\rm L}_\\odot]\\sim 9.9$) at $z=0.40$, and more luminous,\nwarmer systems ($T_{\\rm dust}\\sim 34$k; $\\log[L_{\\rm IR}/{\\rm L}_\\odot]\\sim\n11.5$) at $z=2.23$. Using a modified greybody model, we estimate\n\"characteristic sizes\" for the dust-emitting regions of HiZELS galaxies of\n$\\sim 0.5$kpc, nearly an order of magnitude smaller than their stellar\ncontinuum sizes, which may provide indirect evidence of clumpy ISM structure.\nLastly, we measure the dust masses from our far-IR SEDs along with\nmetallicity-dependent gas-to-dust ratios ($\\delta_{\\rm GDR}$) to measure\ntypical molecular gas masses of $\\sim 10^{10}$M$_\\odot$ for these bright\nH$\\alpha$-emitters. The gas depletion timescales are shorter than the Hubble\ntime at each redshift, suggesting probable replenishment of their gas\nreservoirs from the intergalactic medium. Based on the number density of\nH$\\alpha$-selected galaxies, we find that typical star-forming galaxies\nbrighter than $0.2L^{\\star}_{{\\rm H}\\alpha}(z)$ host a significant fraction\n($35\\pm10$%) of the total gas content of the Universe, consistent with the\npredictions of the latest cosmological simulations.", "positive": "A large sample of Kohonen selected E+A (post-starburst) galaxies from\n the Sloan Digital Sky Survey: We aim to create a large sample of local post-starburst (PSB) galaxies to\nstudy their characteristic properties, particularly morphological features\nindicative of gravitational distortions and indications for active galactic\nnuclei (AGNs). The selection is based on a huge Kohonen self-organising map\n(SOM) of about one million SDSS spectra. The SOM is made fully available for\nthe astronomical community, in combination with an interactive user interface.\nWe compiled a catalogue of 2665 PSB galaxies with redshifts z < 0.4. In the\ncolour-mass diagram, the PSB sample is found to be clearly concentrated towards\nthe region between the red and the blue cloud, in agreement with the idea that\nPSB galaxies represent the transitioning phase between actively and passively\nevolving galaxies. The relative frequency of morphologically distorted PSB\ngalaxies is at least 57%, significantly higher than in a comparison sample. The\nsearch for AGNs based on conventional selection criteria in the radio and MIR\nresults in a low AGN fraction of 2 - 3%. We confirm an MIR excess in the mean\nSED of the PSB galaxy sample that may indicate hidden AGNs, though other\nsources are also possible. (Abstract modified to match the arXiv format.)" }, { "anchor": "Calibration of AGN Reverberation Distance Measurements: In Yoshii et al. (2014), we described a new method for measuring\nextragalactic distances based on dust reverberation in active galactic nuclei\n(AGNs), and we validated our new method with Cepheid variable stars. In this\npaper, we validate our new method with Type Ia supernovae (SNe Ia) which\noccurred in two of the AGN host galaxies during our AGN monitoring program: SN\n2004bd in NGC 3786 and SN 2008ec in NGC 7469. Their multicolor light curves\nwere observed and analyzed using two widely accepted methods for measuring SN\ndistances, and the distance moduli derived are $\\mu=33.47\\pm 0.15$ for SN\n2004bd and $33.83\\pm 0.07$ for SN 2008ec. These results are used to obtain\nindependently the distance measurement calibration factor, $g$. The $g$ value\nobtained from the SN Ia discussed in this paper is $g_{\\rm SN} = 10.61\\pm 0.50$\nwhich matches, within the range of 1$\\sigma$ uncertainty, $g_{\\rm DUST} =\n10.60$, previously calculated ab initio in Yoshii et al. (2014). Having\nvalidated our new method for measuring extragalactic distances, we use our new\nmethod to calibrate reverberation distances derived from variations of H$\\beta$\nemission in the AGN broad line region (BLR), extending the Hubble diagram to\n$z\\approx 0.3$ where distinguishing between cosmologies is becoming possible.", "positive": "A census of ionized gas outflows in type 1 AGNs: gas outflows in AGNs. V: We present a systematic study of ionized gas outflows based on the velocity\nshift and dispersion of the [O III] {\\lambda}5007 $\\AA$ emission line, using a\nsample of ~ 5000 Type 1 AGNs at z < 0.3 selected from Sloan Digital Sky Survey.\nThis analysis is supplemented by the gas kinematics of Type 2 AGNs from Woo et\nal. (2016). For the majority of Type 1 AGNs (i.e., ~ 89%), the [O III] line\nprofile is best represented by a double Gaussian model, presenting the\nkinematic signature of the non-virial motion. Blueshifted [O III] is more\nfrequently detected than redshifted [O III] by a factor of 3.6 in Type 1 AGNs,\nwhile the ratio between blueshifted to redshifted [O III] is only 1.08 in Type\n2 AGNs due to the projection and orientation effect. The fraction of AGNs with\noutflow signatures is found to increase steeply with [O III] luminosity and\nEddington ratio, while Type 1 AGNs have larger velocity dispersion and more\nnegative velocity shift than Type 2 AGNs. The [O III] velocity - velocity\ndispersion (VVD) diagram of Type 1 AGNs expands towards higher values with\nincreasing luminosity and Eddington ratio, suggesting that the radiation\npressure or wind is the main driver of gas outflows, as similarly found in Type\n2 AGNs. In contrast, the kinematics of gas outflows is not directly linked to\nthe radio activity of AGN." }, { "anchor": "The unusual ISM in Blue and Dusty Gas Rich Galaxies (BADGRS): The Herschel-ATLAS unbiased survey of cold dust in the local Universe is\ndominated by a surprising population of very blue (FUV-K < 3.5), dust-rich\ngalaxies with high gas fractions (f_HI = M_HI/(M*+M_HI)>0.5)). Dubbed `Blue and\nDusty Gas Rich Sources' (BADGRS) they have cold diffuse dust temperatures, and\nthe highest dust-to-stellar mass ratios of any galaxies in the local Universe.\nHere, we explore the molecular ISM in a representative sample of BADGRS, using\nvery deep CO(J_up=1,2,3) observations across the central and outer disk\nregions. We find very low CO brightnesses (Tp=15-30 mK), despite the bright\nfar-infrared emission and metallicities in the range 0.5 10^{11.8}M_{\\odot}$ are dense ($\\Sigma_{\\rm\n1kpc} > 10^{9}~ M_{\\odot} {\\rm kpc}^{-2}$), suggesting compaction-related\nquenching maintained by halo-related quenching. However, 21% are diffuse,\nindicating only halo quenching. For satellite galaxies in the outskirts of\nhalos, quenching is a strong function of compactness and a weak function of\nhost $M_{\\rm h}$. In the inner halo, $M_{\\rm h}$ dominates quenching, with\n$\\sim 90\\%$ of the satellites being quenched once $M_{\\rm h} >\n10^{13}M_{\\odot}$. This regional effect is greatest for the least massive\nsatellites. As demonstrated via semi-analytic modelling with simple\nprescriptions for quenching, the observed correlations can be explained if\nquenching due to central compactness is rapid while quenching due to halo mass\nis slow." }, { "anchor": "Astrometric Apparent Motion of High-redshift Radio Sources: Radio-loud quasars at high redshift (z > 4) are rare objects in the Universe\nand rarely observed with Very Long Baseline Interferometry (VLBI). But some of\nthem have flux density sufficiently high for monitoring of their apparent\nposition. The instability of the astrometric positions could be linked to the\nastrophysical process in the jetted active galactic nuclei in the early\nUniverse. Regular observations of the high-redshift quasars are used for\nestimating their apparent proper motion over several years. We have undertaken\nregular VLBI observations of several high-redshift quasars at 2.3 GHz (S band)\nand 8.4 GHz (X band) with a network of five radio telescopes: 40-m Yebes\n(Spain), 25-m Sheshan (China), and three 32-m telescopes of the Quasar VLBI\nNetwork (Russia) -- Svetloe, Zelenchukskaya, and Badary. Additional facilities\njoined this network occasionally. The sources have also been observed in three\nsessions with the European VLBI Network (EVN) in 2018--2019 and one Long\nBaseline Array (LBA) experiment in 2018. In addition, several experiments\nconducted with the Very Long Baseline Array (VLBA) in 2017--2018were used to\nimprove the time sampling and the statistics. Based on these 37 astrometric\nVLBI experiments between 2017 and 2021, we estimated the apparent proper\nmotions of four quasars: 0901+697, 1428+422, 1508+572, and 2101+600.", "positive": "The Origins of Off-Centre Massive Black Holes in Dwarf Galaxies: Massive black holes often exist within dwarf galaxies, and both simulations\nand observations have shown that a substantial fraction of these may be\noff-center with respect to their hosts. We trace the evolution of off-center\nmassive black holes (MBHs) in dwarf galaxies using cosmological hydrodynamical\nsimulations, and show that the reason for off-center locations is mainly due to\ngalaxy-galaxy mergers. We calculate dynamical timescales and show that\noff-center MBHs are unlikely to sink to their galaxys' centers within a Hubble\ntime, due to the shape of the hosts' potential wells and low stellar densities.\nThese wandering MBHs are unlikely to be detected electromagnetically, nor is\nthere a measurable dynamical effect on the galaxy's stellar population. We\nconclude that off-center MBHs may be common in dwarfs, especially if the mass\nof the MBH is small or the stellar mass of the host galaxy is large. However\ndetecting them is extremely challenging, because their accretion luminosities\nare very low and they do not measurably alter the dynamics of their host\ngalaxies." }, { "anchor": "Young Stellar Objects close to Sgr A*: We aim at modelling small groups of young stars such as IRS 13N, 0.1 pc away\nfrom Sgr A*, which is suggested to contain a few embedded massive young stellar\nobjects. We perform hydrodynamical simulations to follow the evolution of\nmolecular clumps orbiting about a $4\\times10^6 ~ M_{\\odot}$ black hole, to\nconstrain the formation and the physical conditions of such groups. We find\nthat, the strong compression due to the black hole along the orbital radius\nvector of clumps evolving on highly eccentric orbits causes the clumps\ndensities to increase to higher than the tidal density of Sgr A*, and required\nfor star formation. This suggests that the tidal compression from the black\nhole could support star formation. Additionally, we speculate that the infrared\nexcess source G2/DSO approaching Sgr A* on a highly eccentric orbit could be\nassociated with a dust enshrouded star that may have been formed recently\nthrough the mechanism supported by our models.", "positive": "Formation of LISA Black Hole Binaries in Merging Dwarf Galaxies: the\n Imprint of Dark Matter: Theoretical models for the expected merger rates of intermediate-mass black\nholes (IMBHs) are vital for planned gravitational-wave detection experiments\nsuch as the Laser Interferometer Space Antenna (LISA). Using collisionless\n$N$-body simulations of dwarf galaxy (DG) mergers, we examine how the orbital\ndecay of IMBHs and the efficiency of IMBH binary formation depend on the\ncentral dark matter (DM) density profile of the merging DGs. Specifically, we\nexplore various asymptotic inner slopes $\\gamma$ of the DG's DM density\ndistribution, ranging from steep cusps ($\\gamma=1$) to shallower density\nprofiles ($\\gamma<1$), motivated by well-known baryonic-feedback effects as\nwell as by DM models that differ from cold DM at the scales of DGs. We find\nthat the inner DM slope is crucial for the formation (or lack thereof) of an\nIMBH binary; only mergers between DGs with cuspy DM profiles ($\\gamma=1$) are\nfavourable to forming a hard IMBH binary, whereas when $\\gamma<1$ the IMBHs\nstall at a separation of 50-100 pc. Consequently, the rate of LISA signals from\nIMBH coalescence will be determined by the fraction of DGs with a cuspy DM\nprofile. Conversely, the LISA event rates at IMBH mass scales offer in\nprinciple a novel way to place constraints on the inner structure of DM halos\nin DGs and address the core-cusp controversy. We also show that, with spatial\nresolutions of $\\sim$0.1 kpc, as often adopted in cosmological simulations, all\nIMBHs stall, independent of $\\gamma$. This suggests caution in employing\ncosmological simulations of galaxy formation to study BH dynamics in DGs." }, { "anchor": "Dark matter distributions around massive black holes: A general\n relativistic analysis: The cold dark matter at the center of a galaxy will be redistributed by the\npresence of a massive black hole. The redistribution may be determined using an\napproach pioneered by Gondolo and Silk: begin with a model distribution\nfunction for the dark matter, and ``grow'' the black hole adiabatically,\nholding the adiabatic invariants of the motion constant. Unlike the approach of\nGondolo and Silk, which adopted Newtonian theory together with ad hoc\ncorrection factors to mimic general relativistic effects, we carry out the\ncalculation fully relativistically, using the exact Schwarzschild geometry of\nthe black hole. We find that the density of dark matter generically vanishes at\nr=2R_S, not 4R_S as found by Gondolo and Silk, where R_S is the Schwarzschild\nradius, and that the spike very close to the black hole reaches significantly\nhigher densities. We apply the relativistic adiabatic growth framework to\nobtain the final dark matter density for both cored and cusped initial\ndistributions. Besides the implications of these results for indirect detection\nestimates, we show that the gravitational effects of such a dark matter spike\nare significantly smaller than the relativistic effects of the black hole,\nincluding frame dragging and quadrupolar effects, for stars orbiting close to\nthe black hole that might be candidates for testing the black hole no-hair\ntheorems.", "positive": "Compact dusty clouds and efficient H$_2$ formation in diffuse ISM: The formation of compact dusty clouds in diffuse interstellar medium (ISM)\nhas been recently proposed and studied by Tsytovich et al. (2014). In the\npresent paper, an effect of the clouds on the rate of H$\\to$H$_2$ transition in\nthe ISM is examined. We discuss the mechanisms leading to the formation of the\nclouds and the creation of gaseous clumps around them, analyze the main\nprocesses determining the efficiency of the recombination of atomic hydrogen on\ndust grains, and estimate the expected enhancement of the global H$_2$\nformation due to the presence of the clouds. In conclusion, we argue that the\ncompact dusty clouds provide optimum conditions for the atomic recombination in\ndiffuse ISM, and point out some astrophysical implications of the resulting\nH$_2$ formation enhancement." }, { "anchor": "Candidate Massive Galaxies at $z \\sim 4$ in the Dark Energy Survey: Using stellar population models, we predicted that the Dark Energy Survey\n(DES) - due to its special combination of area (5000 deg. sq.) and depth ($i =\n24.3$) - would be in the position to detect massive ($\\gtrsim 10^{11}$\nM$_{\\odot}$) galaxies at $z \\sim 4$. We confront those theoretical calculations\nwith the first $\\sim 150$ deg. sq. of DES data reaching nominal depth. From a\ncatalogue containing $\\sim 5$ million sources, $\\sim26000$ were found to have\nobserved-frame $g-r$ vs $r-i$ colours within the locus predicted for $z \\sim 4$\nmassive galaxies. We further removed contamination by stars and artefacts,\nobtaining 606 galaxies lining up by the model selection box. We obtained their\nphotometric redshifts and physical properties by fitting model templates\nspanning a wide range of star formation histories, reddening and redshift. Key\nto constrain the models is the addition, to the optical DES bands $g$, $r$,\n$i$, $z$, and $Y$, of near-IR $J$, $H$, $K_{s}$ data from the Vista Hemisphere\nSurvey. We further applied several quality cuts to the fitting results,\nincluding goodness of fit and a unimodal redshift probability distribution. We\nfinally select 233 candidates whose photometric redshift probability\ndistribution function peaks around $z\\sim4$, have high stellar masses\n($\\log($M$^{*}$/M$_{\\odot})\\sim 11.7$ for a Salpeter IMF) and ages around 0.1\nGyr, i.e. formation redshift around 5. These properties match those of the\nprogenitors of the most massive galaxies in the local universe. This is an\nideal sample for spectroscopic follow-up to select the fraction of galaxies\nwhich is truly at high redshift. These initial results and those at the survey\ncompletion, which we shall push to higher redshifts, will set unprecedented\nconstraints on galaxy formation, evolution, and the re-ionisation epoch.", "positive": "Cosmological Simulations of Galaxy Formation: Over the last decades, cosmological simulations of galaxy formation have been\ninstrumental for advancing our understanding of structure and galaxy formation\nin the Universe. These simulations follow the non-linear evolution of galaxies\nmodeling a variety of physical processes over an enormous range of scales. A\nbetter understanding of the physics relevant for shaping galaxies, improved\nnumerical methods, and increased computing power have led to simulations that\ncan reproduce a large number of observed galaxy properties. Modern simulations\nmodel dark matter, dark energy, and ordinary matter in an expanding space-time\nstarting from well-defined initial conditions. The modeling of ordinary matter\nis most challenging due to the large array of physical processes affecting this\nmatter component. Cosmological simulations have also proven useful to study\nalternative cosmological models and their impact on the galaxy population. This\nreview presents a concise overview of the methodology of cosmological\nsimulations of galaxy formation and their different applications." }, { "anchor": "The 'Big Dipper': The nature of the extreme variability of the AGN SDSS\n J2232-0806: SDSS J2232-0806 (the 'Big Dipper') has been identified as a 'slow-blue\nnuclear hypervariable': a galaxy with no previously known active nucleus, blue\ncolours and large-amplitude brightness evolution occurring on a timescale of\nyears. Subsequent observations have shown that this source does indeed contain\nan active galactic nucleus (AGN). Our optical photometric and spectroscopic\nmonitoring campaign has recorded one major dimming event (and subsequent rise)\nover a period of around four years; there is also evidence of previous events\nconsistent with this in archival data recorded over the last twenty years. Here\nwe report an analysis of the eleven optical spectra obtained to date and we\nassemble a multiwavelength data set including infrared, ultraviolet and X-ray\nobservations. We find that an intrinsic change in the luminosity is the most\nfavoured explanation of the observations, based on a comparison of continuum\nand line variability and the apparent lagged response of the hot dust. This\nsource, along with several other recently-discovered 'changing-look' objects,\ndemonstrate that AGN can exhibit large-amplitude luminosity changes on\ntimescales much shorter than those predicted by standard thin accretion disc\nmodels.", "positive": "Tailed Radio Galaxies from the TIFR GMRT Sky Survey: We present a list of candidate tailed radio galaxies using the TIFR GMRT Sky\nSurvey Alternative Data Release 1 (TGSS ADR1) at 150 MHz. We have visually\nexamined 5336 image fields and found 264 candidates for the tailed galaxy.\nTailed radio galaxies are classified as Wide Angle Tailed (WAT) galaxies and\nNarrow-Angle Tailed (NAT) galaxies, based on the angle between the two jets of\nthe galaxy. We found a sample of tailed radio galaxies which includes 203 `WAT'\nand 61 `NAT' type sources. These newly identified tailed sources are\nsignificant additions to the list of known tailed radio galaxies. The source\nmorphology and luminosity features of the different candidate galaxies and\ntheir optical identifications are presented in the paper. Other radio\nproperties and general features of the sources are also discussed." }, { "anchor": "Nuclei of dwarf spheroidal galaxies KKs3 and ESO269-66 and their\n counterparts in our Galaxy: We present the analysis of medium-resolution spectra obtained at the Southern\nAfrican Large Telescope (SALT) for nuclear globular clusters (GCs) in two dwarf\nspheroidal galaxies (dSphs). The galaxies have similar star formation\nhistories, but they are situated in completely different environments.\nESO269-66 is a close neighbour of the giant S0 NGC5128. KKs3 is one of the few\ntruly isolated dSphs within 10 Mpc. We estimate the helium abundance $Y=0.3$,\n$\\rm age=12.6\\pm1$ Gyr, $[Fe/H]=-1.5,-1.55\\pm0.2$ dex, and abundances of C, N,\nMg, Ca, Ti, and Cr for the nuclei of ESO269-66 and KKs3. Our surface photometry\nresults using HST images yield the half-light radius of the cluster in KKs3,\n$\\rm r_h=4.8\\pm0.2$ pc. We demonstrate the similarities of medium-resolution\nspectra, ages, chemical compositions, and structure for GCs in ESO269-66 and\nKKs3 and for several massive Galactic GCs with $[Fe/H]\\sim-1.6$ dex. All\nGalactic GCs posses Extended Blue Horizontal Branches and multiple stellar\npopulations. Five of the selected Galactic objects are iron-complex GCs. Our\nresults indicate that the sample GCs observed now in different environments had\nsimilar conditions of their formation $\\sim$1 Gyr after the Big Bang.", "positive": "Joint Bayesian Estimation of Quasar Continua and the Lyman-Alpha Forest\n Flux Probability Distribution Function: We present a new Bayesian algorithm making use of Markov Chain Monte Carlo\nsampling that allows us to simultaneously estimate the unknown continuum level\nof each quasar in an ensemble of high-resolution spectra, as well as their\ncommon probability distribution function (PDF) for the transmitted Ly$\\alpha$\nforest flux. This fully automated PDF regulated continuum fitting method models\nthe unknown quasar continuum with a linear Principal Component Analysis (PCA)\nbasis, with the PCA coefficients treated as nuisance parameters. The method\nallows one to estimate parameters governing the thermal state of the\nintergalactic medium (IGM), such as the slope of the temperature-density\nrelation $\\gamma-1$, while marginalizing out continuum uncertainties in a fully\nBayesian way. Using realistic mock quasar spectra created from a simplified\nsemi-numerical model of the IGM, we show that this method recovers the\nunderlying quasar continua to a precision of $\\simeq7\\%$ and $\\simeq10\\%$ at\n$z=3$ and $z=5$, respectively. Given the number of principal component spectra,\nthis is comparable to the underlying accuracy of the PCA model itself. Most\nimportantly, we show that we can achieve a nearly unbiased estimate of the\nslope $\\gamma-1$ of the IGM temperature-density relation with a precision of\n$\\pm8.6\\%$ at $z=3$, $\\pm6.1\\%$ at $z=5$, for an ensemble of ten mock\nhigh-resolution quasar spectra. Applying this method to real quasar spectra and\ncomparing to a more realistic IGM model from hydrodynamical simulations would\nenable precise measurements of the thermal and cosmological parameters\ngoverning the IGM, albeit with somewhat larger uncertainties given the\nincreased flexibility of the model." }, { "anchor": "10-100 TeV cosmic ray anisotropy measured at Baksan EAS \"Carpet\" array: Preliminary results of one year anisotropy measurement in the energy range\n10^{13} -10^{14} eV as a function of energy are presented. The results are\ncompared for two methods of data analysis: the standard one with meteo\ncorrection approach in use and another one so-called \"East minus West\" method.\nAmplitudes and phases of anisotropy for three median energies E = 25 TeV, E =\n75 TeV and E = 120 TeV are reported. Brief consideration of amplitude-phase\ndependence of anisotropy on energy is expounded.", "positive": "A Systematic Study on the Absorption Features of Interstellar Ices in\n Presence of Impurities: Spectroscopic studies play a key role in the identification and analysis of\ninterstellar ices and their structure. Some molecules have been identified\nwithin the interstellar ices either as pure, mixed, or even as layered\nstructures. Absorption band features of water ice can significantly change with\nthe presence of different types of impurities (CO, CO2, CH3OH, H2CO, etc.). In\nthis work, we carried out a theoretical investigation to understand the\nbehavior of water band frequency, and strength in the presence of impurities.\nThe computational study has been supported and complemented by some infrared\nspectroscopy experiments aimed at verifying the effect of HCOOH, NH3 , and CH3\nOH on the band profiles of pure H2O ice. Specifically, we explored the effect\non the band strength of libration, bending, bulk stretching, and free-OH\nstretching modes. Computed band strength profiles have been compared with our\nnew and existing experimental results, thus pointing out that vibrational modes\nof H2O and their intensities can change considerably in the presence of\nimpurities at different concentrations. In most cases, the bulk stretching mode\nis the most affected vibration, while the bending is the least affected mode.\nHCOOH was found to have a strong influence on the libration, bending, and bulk\nstretching band profiles. In the case of NH3, the free-OH stretching band\ndisappears when the impurity concentration becomes 50%. This work will\nultimately aid a correct interpretation of future detailed spaceborne\nobservations of interstellar ices by means of the upcoming JWST mission." }, { "anchor": "A New Photometric Model of the Galactic Bar using Red Clump Giants: We present a study of the luminosity density distribution of the Galactic bar\nusing number counts of red clump giants (RCGs) from the OGLE-III survey. The\ndata were recently published by Nataf et al. (2013) for 9019 fields towards the\nbulge and have $2.94\\times 10^6$ RC stars over a viewing area of $90.25\n\\,\\textrm{deg}^2$. The data include the number counts, mean distance modulus\n($\\mu$), dispersion in $\\mu$ and full error matrix, from which we fit the data\nwith several tri-axial parametric models. We use the Markov Chain Monte Carlo\n(MCMC) method to explore the parameter space and find that the best-fit model\nis the $E_3$ model, with the distance to the GC is 8.13 kpc, the ratio of\nsemi-major and semi-minor bar axis scale lengths in the Galactic plane\n$x_{0},y_{0}$, and vertical bar scale length $z_0$, is $x_0:y_0:z_0 \\approx\n1.00:0.43:0.40$ (close to being prolate). The scale length of the stellar\ndensity profile along the bar's major axis is $\\sim$ 0.67 kpc and has an angle\nof $29.4^\\circ$, slightly larger than the value obtained from a similar study\nbased on OGLE-II data. The number of estimated RC stars within the field of\nview is $2.78 \\times 10^6$, which is systematically lower than the observed\nvalue. We subtract the smooth parametric model from the observed counts and\nfind that the residuals are consistent with the presence of an X-shaped\nstructure in the Galactic centre, the excess to the estimated mass content is\n$\\sim 5.8%$. We estimate the total mass of the bar is $\\sim 1.8 \\times 10^{10}\nM_\\odot$. Our results can be used as a key ingredient to construct new density\nmodels of the Milky Way and will have implications on the predictions of the\noptical depth to gravitational microlensing and the patterns of hydrodynamical\ngas flow in the Milky Way.", "positive": "Constraints on the distribution of gas and young stars in the Galactic\n Centre in the context of interpreting gamma ray emission features: Gamma ray observations have found evidence of an extremely energetic outflow\nemanating from the Galactic Centre, and an `excess' of emission at GeV energies\ntowards the Galactic Centre over that expected from current models. Determining\nwhether the outflow is AGN- or star formation-driven, and whether the `excess'\nis astrophysical in origin or requires new physics (e.g. self-annihilation of\ndark matter), requires the accurate modelling of the expected energy injection\nfrom astrophysical sources and the subsequent interaction with the surrounding\nenvironment. We briefly summarise current constraints on the distribution of\ngas and young stars in the inner few hundred parsec of the Galaxy that can be\nincluded in future 2D and 3D modelling of the astrophysical gamma ray emission.\nThe key points to highlight with respect to predominantly axisymmetric models\ncurrently in use are: (i) the distribution of dense gas, young stars and\ninterstellar radiation field is highly asymmetric around the Galactic Centre;\n(ii) star formation is almost exclusively constrained to a Galactocentric\nradius of ~100pc; (iii) the star formation rate in this region has been\nconstant at <0.1Msun/yr to within a factor of 2 over the last ~5 Myr." }, { "anchor": "Carbon chemistry in Galactic Bulge Planetary Nebulae: Galactic Bulge Planetary Nebulae show evidence of mixed chemistry with\nemission from both silicate dust and PAHs. This mixed chemistry is unlikely to\nbe related to carbon dredge up, as third dredge-up is not expected to occur in\nthe low mass Bulge stars. We show that the phenomenon is widespread, and is\nseen in 30 nebulae out of 40 of our sample, selected on the basis of their\ninfrared flux. HST images and UVES spectra show that the mixed chemistry is not\nrelated to the presence of emission-line stars, as it is in the Galactic disk\npopulation. We also rule out interaction with the ISM as origin of the PAHs.\nInstead, a strong correlation is found with morphology, and the presence of a\ndense torus. A chemical model is presented which shows that hydrocarbon chains\ncan form within oxygen-rich gas through gas-phase chemical reactions. The model\npredicts two layers, one at $A_V\\sim 1.5$ where small hydrocarbons form from\nreactions with C$^+$, and one at $A_V\\sim 4$, where larger chains (and by\nimplication, PAHs) form from reactions with neutral, atomic carbon. These\nreactions take place in a mini-PDR. We conclude that the mixed chemistry\nphenomenon occurring in the Galactic Bulge Planetary Nebulae is best explained\nthrough hydrocarbon chemistry in an UV-irradiated, dense torus.", "positive": "Far-Infrared Polarization Spectrum of the OMC-1 Star-Forming Region: We analyze the wavelength dependence of the far-infrared polarization\nfraction toward the OMC-1 star forming region using observations from\nHAWC+/SOFIA at 53, 89, 154, and 214 $\\mu$m. We find that the shape of the\nfar-infrared polarization spectrum is variable across the cloud and that there\nis evidence of a correlation between the slope of the polarization spectrum and\nthe average line-of-sight temperature. The slope of the polarization spectrum\ntends to be negative (falling toward longer wavelengths) in cooler regions and\npositive or flat in warmer regions. This is very similar to what was discovered\nin $\\rho$ Oph A via SOFIA polarimetry at 89 and 154 $\\mu$m. Like the authors of\nthis earlier work, we argue that the most natural explanation for our falling\nspectra is line-of-sight superposition of differing grain populations, with\npolarized emission from the warmer regions and less-polarized emission from the\ncooler ones. In contrast with the earlier work on $\\rho$ Oph A, we do not find\na clear correlation of polarization spectrum slope with column density. This\nsuggests that falling spectra are attributable to variations in grain alignment\nefficiency in a heterogeneous cloud consistent with radiative torques theory.\nAlternative explanations in which variations in grain alignment efficiency are\ncaused by varying gas density rather than by varying radiation intensity are\ndisfavored." }, { "anchor": "The redshift evolution of major merger triggering of luminous AGN: a\n slight enhancement at z$\\sim$2: Active galactic nuclei (AGN), particularly the most luminous AGN, are\ncommonly assumed to be triggered through major mergers, however observational\nevidence for this scenario is mixed. To investigate any influence of galaxy\nmergers on AGN triggering and luminosities through cosmic time, we present a\nsample of 106 luminous X-ray selected type 1 AGN from the COSMOS survey. These\nAGN occupy a large redshift range (0.5 < z < 2.2) and two orders of magnitude\nin X-ray luminosity ($\\sim$10$^{43}$ - 10$^{45}$ erg s$^{-1}$). AGN hosts are\ncarefully mass and redshift matched to 486 control galaxies. A novel technique\nfor identifying and quantifying merger features in galaxies is developed,\nsubtracting GALFIT galaxy models and quantifying the residuals. Comparison to\nvisual classification confirms this measure reliably picks out disturbance\nfeatures in galaxies. No enhancement of merger features with increasing AGN\nluminosity is found with this metric, or by visual inspection. We analyse the\nredshift evolution of AGN associated with galaxy mergers and find no merger\nenhancement in lower redshift bins. Contrarily, in the highest redshift bin\n(z$\\sim$2) AGN are $\\sim$4 times more likely to be in galaxies exhibiting\nevidence of morphological disturbance compared to control galaxies, at 99%\nconfidence level ($\\sim$2.4$\\sigma$) from visual inspection. Since only\n$\\sim$15% of these AGN are found to be in morphologically disturbed galaxies,\nit is implied that major mergers at high redshift make a noticeable but\nsubdominant contribution to AGN fuelling. At low redshifts other processes\ndominate and mergers become a less significant triggering mechanism.", "positive": "Towards a census of the Galactic anticentre star clusters:\n colour-magnitude diagram and structural analyses of a sample of 50 objects: In this work we investigate the nature of 50 overdensities from the catalogue\nof Froebrich, Scholz, and Raftery (FSR) projected towards the Galactic\nanticentre, in the sector 160{\\deg} \\leq \\ell \\leq 200{\\deg}. The sample\ncontains candidates with |b| \\leq 20{\\deg} classified by FSR as probable open\ncluster (OC) and labelled with quality flags 2 and 3. Our main purpose is to\ndetermine the nature of these OC candidates and the fraction of these objects\nthat are unknown OCs, as well as to derive astrophysical parameters (age,\nreddening, distance, core and cluster radii) for the clusters and to\ninvestigate the relationship among parameters. The analysis is based on 2MASS\nJ, (J-H), and (J-Ks) colour-magnitude diagrams (CMDs), and stellar radial\ndensity profiles (RDPs) built with decontamination tools. The tools are a field\nstar decontamination algorithm, used to uncover the cluster's intrinsic CMD\nmorphology, and colour-magnitude filters to isolate stars with a high\nprobability of being cluster members. Out of the 50 objects, 16 (32%) are star\nclusters. We show that 9 (18%) overdensities are new OCs (FSR 735, FSR 807, FSR\n812, FSR 826, FSR 852, FSR 904, FSR 941, FSR 953, and FSR 955) and 7 (14%) are\npreviously studied or catalogued OCs (KKC1, FSR 795, Cz 22, FSR 828, FSR 856,\nCz 24, and NGC 2234). These are OCs with ages in the range 5 Myr to 1 Gyr, at\ndistances from the Sun 1.28 \\precnapprox d_Sun(kpc) \\precnapprox 5.78 and\nGalactocentric distances 8.5 R_GC(kpc) \\precnapprox 12.9. We also derive\nparameters for the previously analysed OCs Cz 22 and NGC 2234. Five (10%)\ncandidates are classified as uncertain cases, and the remaining objects are\nprobable field fluctuations." }, { "anchor": "The imprint of clump formation at high redshift. II. The chemistry of\n the bulge: In Paper I we showed that clumps in high-redshift galaxies, having a high\nstar formation rate density (\\Sigma_SFR), produce disks with two tracks in the\n[Fe/H]-[\\alpha/Fe] chemical space, similar to that of the Milky Way's (MW's)\nthin + thick disks. Here we investigate the effect of clumps on the bulge's\nchemistry. The chemistry of the MW's bulge is comprised of a single track with\ntwo density peaks separated by a trough. We show that the bulge chemistry of an\nN-body + smoothed particle hydrodynamics clumpy simulation also has a single\ntrack. Star formation within the bulge is itself in the high-\\Sigma_SFR clumpy\nmode, which ensures that the bulge's chemical track follows that of the thick\ndisk at low [Fe/H] and then extends to high [Fe/H], where it peaks. The peak at\nlow metallicity instead is comprised of a mixture of in-situ stars and stars\naccreted via clumps. As a result, the trough between the peaks occurs at the\nend of the thick disk track. We find that the high-metallicity peak dominates\nnear the mid-plane and declines in relative importance with height, as in the\nMW. The bulge is already rapidly rotating by the end of the clump epoch, with\nhigher rotation at low [\\alpha/Fe]. Thus clumpy star formation is able to\nsimultaneously explain the chemodynamic trends of the MW's bulge, thin + thick\ndisks and the Splash.", "positive": "A near-infrared study of the multi-phase outflow in the type-2 quasar\n J1509+0434: Based on new near-infrared spectroscopic data from the instrument EMIR on the\n10.4 m Gran Telescopio Canarias (GTC) we report the presence of an ionized and\nwarm molecular outflow in the luminous type-2 quasar J150904.22+043441.8 (z =\n0.1118). The ionized outflow is faster than its molecular counterpart, although\nthe outflow sizes that we derive for them are consistent within the errors\n(1.34$\\pm$0.18 kpc and 1.46$\\pm$0.20 kpc respectively). We use these radii, the\nbroad emission-line luminosities and in the case of the ionized outflow, the\ndensity calculated from the trans-auroral [OII] and [SII] lines, to derive mass\noutflow rates and kinetic coupling efficiencies. Whilst the ionized and warm\nmolecular outflows represent a small fraction of the AGN power ($\\leq$0.033%\nand 0.0001% of L$_{bol}$ respectively), the total molecular outflow, whose mass\nis estimated from an assumed warm-to-cold gas mass ratio of 6$\\times10^{-5}$,\nhas a kinetic coupling efficiency of $\\sim$1.7%L$_{bol}$. Despite the large\nuncertainty, this molecular outflow represents a significant fraction of\nL$_{bol}$ and it could potentially have a significant impact on the host\ngalaxy. In addition, the quasar spectrum reveals bright and patchy narrow\nPa$\\alpha$ emission extending out to 4 arcsec (8 kpc) South-East and North-West\nfrom the active nucleus." }, { "anchor": "Gas accretion and Ram Pressure Stripping of Haloes in Void Walls: We conduct hydrodynamical cosmological zoom simulations of fourteen voids to\nstudy the ability of haloes to accrete gas at different locations throughout\nthe voids at z = 0. Measuring the relative velocity of haloes with respect to\ntheir ambient gas, we find that a tenth of the haloes are expected to be unable\nto accrete external gas due to its fast flow passed them (so called 'fast flow\nhaloes'). These are typically located near void walls. We determine that these\nhaloes have recently crossed the void wall and are still moving away from it.\ntheir motion counter to that of ambient gas falling towards the void wall\nresults in fast flows that make external gas accretion very challenging, and\noften cause partial gas loss via the resultant ram pressures. Using an\nanalytical approach, we model the impact of such ram pressures on the gas\ninside haloes of different masses. A halo's external gas accretion is typically\ncut off, with partial stripping of halo gas. For masses below a few times\n10$^{9}$ M$_{\\odot}$, their halo gas is heavily truncated but not completely\nstripped. We identify numerous examples of haloes with a clear jelly-fish like\ngas morphology, indicating their surrounding gas is being swept away, cutting\nthem off from further external accretion. These results highlight how, even in\nthe relatively low densities of void walls, a fraction of galaxies can interact\nwith large-scale flows in a manner that has consequences for their gas content\nand ability to accrete gas.", "positive": "All good things come in threes: the third image of the lensed quasar\n PKS1830-211: Strong gravitational lensing distorts our view of sources at cosmological\ndistances but brings invaluable constraints on the mass content of foreground\nobjects and on the geometry and properties of the Universe. We report the\ndetection of a third continuum source toward the strongly lensed quasar\nPKS1830-211 in ALMA multi-frequency observations of high dynamic range and high\nangular resolution. This third source is point-like and located slightly to the\nnorth of the diagonal joining the two main lensed images, A and B, 0.3 arcsec\naway from image B. It has a flux density that is ~140 times weaker than images\nA and B and a similar spectral index, compatible with synchrotron emission. We\nconclude that this source is most likely the expected highly de-magnified third\nlensed image of the quasar. In addition, we detect, for the first time at\nmillimeter wavelengths, weak and asymmetrical extensions departing from images\nA and B that correspond to the brightest regions of the Einstein ring seen at\ncentimeter wavelengths. Their spectral index is steeper than that of compact\nimages A, B, and C, which suggests that they arise from a different component\nof the quasar. Using the GravLens code, we explore the implications of our\nfindings on the lensing model and propose a simple model that accurately\nreproduces our ALMA data and previous VLA observations. With a more precise and\naccurate measurement of the time delay between images A and B, the system\nPKS1830-211 could help to constrain the Hubble constant to a precision of a few\npercent." }, { "anchor": "On the local dark matter density: An analysis of the kinematics of 412 stars at 1-4 kpc from the Galactic\nmid-plane by Moni Bidin et al. (2012) has claimed to derive a local density of\ndark matter that is an order of magnitude below standard expectations. We show\nthat this result is incorrect and that it arises from the assumption that the\nmean azimuthal velocity of the stellar tracers is independent of Galactocentric\nradius at all heights. We substitute the assumption, supported by data, that\nthe circular speed is independent of radius in the mid-plane. We demonstrate\nthat the assumption of constant mean azimuthal velocity is implausible by\nshowing that it requires the circular velocity to drop more steeply than\nallowed by any plausible mass model, with or without dark matter, at large\nheights above the mid-plane. Using the approximation that the circular velocity\ncurve is flat in the mid-plane, we find that the data imply a local dark-matter\ndensity of 0.008 +/- 0.003 Msun/pc^3 = 0.3 +/- 0.1 GeV/cm3, fully consistent\nwith standard estimates of this quantity. This is the most robust direct\nmeasurement of the local dark-matter density to date.", "positive": "Early chemical evolution of Zn driven by magnetorotational supernovae\n and the pathway to the solar Zn composition: The site of Zn production remains an elusive and challenging problem in\nastrophysics. A large enhancement of the [Zn/Fe] ratios of very metal-poor\nstars in the Galactic halo suggests the death of short-lived massive stars,\ni.e., core-collapse supernovae (CCSNe), as one major site for Zn production.\nPrevious studies have claimed that some specific CCSNe can produce Zn in\nsufficient quantities. However, it remains unclear which models can withstand\nthe critical test of observations. Using a Zn abundance feature similar to that\nof r-process elements in faint satellite galaxies, we find evidence that Zn\nproduction took place through much rarer events than canonical CCSNe. This\nfinding can be unified with the implied decrease in the rate of Zn production\nwith an increasing metallicity for Galactic halo stars, which narrows down the\nmajor site of Zn production in the early galaxy to magneto-rotational SNe\n(MR-SNe). On the other hand, in the later phase of galactic evolution, we\npredict that the major Zn-production site switched from MR-SNe to thermonuclear\nSNe (SNe Ia). According to this scenario, an accumulation of the contributions\nfrom two types of SNe eventually led to the solar isotope composition of Zn\nwhich mainly owes 66,68Zn to MR-SNe and 64Zn to SNe Ia triggered by\nHe-detonation. The requirement of Zn production in SNe Ia sheds a new light on\nthe hot debate on the scenario for SN Ia progenitors, suggesting that a\nHe-detonation model might be one major channel for SNe Ia." }, { "anchor": "Formation imprints in the kinematics of the Milky Way globular cluster\n system: We report results on the kinematics of Milky Way (MW) globular clusters (GCs)\nbased on updated space velocities for nearly the entire GC population. We found\nthat a 3D space with the semi-major axis, the eccentricity and the inclination\nof the orbit with respect to the MW plane as its axes is helpful in order to\ndig into the formation of the GC system. We find that GCs formed in-situ show a\nclear correlation between their eccentricities and their orbital inclination in\nthe sense that clusters with large eccentricities also have large inclinations.\nThese GCs also show a correlation between their distance to the MW center and\ntheir eccentricity. Accreted GCs do not exhibit a relationship between\neccentricity and inclination, but span a wide variety of inclinations at\neccentricities larger than ~ 0.5. Finally, we computed the velocity anisotropy\n\"beta\" of the GC system and found for GCs formed in-situ that \"beta\" decreases\nfrom ~ 0.8 down to 0.3 from the outermost regions towards the MW center, but\nremains fairly constant (0.7-0.9) for accreted ones. These findings can be\nexplained if GCs formed from gas that collapsed radially in the outskirts, with\npreference for relative high infall angles. As the material reached the\nrotating forming disk, it became more circular and moved with lower inclination\nrelative to the disk. A half of the GC population was accreted and deposited in\norbits covering the entire range of energies from the outer halo to the bulge.", "positive": "Morphological Transformation and Star Formation Quenching of Massive\n Galaxies at 0.5 < z < 2.5 in 3D-HST/CANDELS: To figure out the effect of stellar mass and local environment on\nmorphological transformation and star formation quenching in galaxies, we use\nthe massive ($M_* \\geq 10^{10} M_{\\odot}$) galaxies at $0.5 \\leq z \\leq 2.5$ in\nfive fields of 3D-HST/CANDELS. Based on the {\\it UVJ} diagnosis and the\npossibility of possessing spheroid, our sample of massive galaxies are\nclassified into four populations: quiescent early-type galaxies (qEs),\nquiescent late-type galaxies (qLs), star-forming early-type galaxies (sEs), and\nstar-forming late-type galaxies (sLs). It is found that the quiescent fraction\nis significantly elevated at the high ends of mass and local environmental\noverdensity, which suggests a clear dependence of quenching on both mass and\nlocal environment. Over cosmic time, the mass dependence of galaxy quiescence\ndecreases while the local environment dependence increases. The early-type\nfraction is found to be larger only at high-mass end, indicating a evident mass\ndependence of morphological transformation. This mass dependence becomes more\nsignificant at lower redshifts. Among the four populations, the fraction of\nactive galactic nucleus (AGN) in the qLs peaks at $2 54 eV, relative to those near 13.6 eV. We suggest two\nplausible mechanisms for the observed behavior: (i) temporary obscuration of\nthe ionizing continuum incident upon BLR clouds by a moving veil of material\nlying between the inner accretion disk and inner BLR, perhaps resulting from an\nepisodic ejection of material from the disk, or (ii) a temporary change in the\nintrinsic ionizing continuum spectral energy distribution resulting in a\ndeficit of ionizing photons with energies > 54 eV, possibly due to a transient\nrestructuring of the Comptonizing atmosphere above the disk. Current evidence\nappears to favor the latter explanation." }, { "anchor": "Elemental Abundances in Milky Way-like Galaxies from a Hierarchical\n Galaxy Formation Model: We develop a new method to account for the finite lifetimes of stars and\ntrace individual abundances within a semi-analytic model of galaxy formation.\nAt variance with previous methods, based on the storage of the (binned) past\nstar formation history of model galaxies, our method projects the information\nabout the metals produced by each simple stellar population (SSP) in the\nfuture. Using this approach, an accurate accounting of the timings and\nproperties of the individual SSPs composing model galaxies is possible. We\nanalyse the dependence of our chemical model on various ingredients, and apply\nit to six simulated haloes of roughly Milky Way mass and with no massive close\nneighbour at z=0. For all models considered, the [Fe/H] distributions of the\nstars in the disc component are in good agreement with Milky Way data, while\nfor the spheroid component (whose formation we model only through mergers)\nthese are offset low with respect to observational measurements for the Milky\nWay bulge. This is a consequence of narrow star formation histories, with\nrelatively low rates of star formation. The slow recycling of gas and energy\nfrom supernovae in our chemical model has important consequences on the\npredicted star formation rates, which are systematically lower than the\ncorresponding rates in the same physical model but with an instantaneous\nrecycling approximation. The halo that resembles most our Galaxy in terms of\nits global properties also reproduces the observed relation between the average\nmetallicity and luminosity of the Milky Way satellites, albeit with a slightly\nsteeper slope.", "positive": "Multiphase turbulence in galactic halos: effect of the driving: Supernova explosions, active galactic nuclei jets, galaxy--galaxy\ninteractions and cluster mergers can drive turbulence in the circumgalactic\nmedium (CGM) and in the intracluster medium (ICM). However, the exact nature of\nturbulence forced by these sources and its impact on the different statistical\nproperties of the CGM/ICM and their global thermodynamics is still unclear. To\ninvestigate the effects of different types of forcing, we conduct high\nresolution ($1008^3$ resolution elements) idealised hydrodynamic simulations\nwith purely solenoidal (divergence-free) forcing, purely compressive\n(curl-free) forcing, and natural mixture forcing (equal fractions of the two\ncomponents). The simulations also include radiative cooling. We study the\nimpact of the three different forcing modes (sol, comp, mix) on the morphology\nof the gas, its temperature and density distributions, sources and sinks of\nenstrophy, i.e., solenoidal motions, as well as the kinematics of hot\n($\\sim10^7~\\mathrm{K}$) X-ray emitting and cold ($\\sim10^4~\\mathrm{K}$)\nH$\\alpha$ emitting gas. We find that compressive forcing leads to stronger\nvariations in density and temperature of the gas as compared to solenoidal\nforcing. The cold phase gas forms large-scale filamentary structures for\ncompressive forcing and misty, small-scale clouds for solenoidal forcing. The\ncold phase gas has stronger large-scale velocities for compressive forcing. The\nnatural mixture forcing shows kinematics and gas distributions intermediate\nbetween the two extremes, the cold-phase gas occurs as both large-scale\nfilaments and small-scale misty clouds." }, { "anchor": "The Close AGN Reference Survey (CARS): An interplay between radio jets\n and AGN radiation in the radio-quiet AGN HE 0040-1105: We present a case study of HE 0040-1105, an unobscured radio-quiet AGN at a\nhigh accretion rate (Eddington ratio = 0.19+/-0.04). This particular AGN hosts\nan ionized gas outflow with the largest spatial offset from its nucleus\ncompared to all other AGNs in the Close AGN Reference Survey (CARS). By\ncombining multi-wavelength observations from VLT/MUSE, HST/WFC3, VLA, and EVN\nwe probe the ionization conditions, gas kinematics, and radio emission from\nhost galaxy scales to the central few pc. We detect four kinematically distinct\ncomponents, one of which is a spatially unresolved AGN-driven outflow located\nwithin the central 500 pc, where it locally dominates the ISM conditions. Its\nvelocity is too low to escape the host galaxy's gravitational potential, and\nmaybe re-accreted onto the central black hole via chaotic cold accretion. We\ndetect compact radio emission in HE 0040-1105,within the region covered by the\noutflow, varying on ~20 yr timescale. We show that neither AGN coronal emission\nnor star formation processes wholly explain the radio morphology/spectrum. The\nspatial alignment between the outflowing ionized gas and the radio continuum\nemission on 100 pc, scales is consistent with a weak jet morphology rather than\ndiffuse radio emission produced by AGN winds. > 90% of the outflowing ionized\ngas emission originates from the central 100 pc, within which the ionizing\nluminosity of the outflow is comparable to the mechanical power of the radio\njet. Although radio jets might primarily drive the outflow in HE 0040-1105,,\nradiation pressure from the AGN may contribute in this process.", "positive": "Infrared Supernova Remnants and their Infrared to X-ray Flux Ratios: Recent high-resolution infrared space missions have revealed supernova\nremnants (SNRs) of diverse morphology in infrared (IR) dust emission that is\noften very different from their X-ray appearance. The observed range of\ninfrared-to-X-ray (IRX) flux ratios of SNRs are also wide. For a sample of 20\nGalactic SNRs, we obtain their IR and X-ray properties and investigate the\nphysical causes for such large differences. We find that the observed IRX flux\nratios ($R_{IRX.obs}$) are related to the IRX morphology, with SNRs with the\nlargest $R_{IRX,obs}$ showing anticorrelated IRX morphology. By analyzing the\nrelation of $R_{IRX,obs}$ to X-ray and IR parameters, we show that the\n$R_{IRX,obs}$ of some SNRs agree with theoretical ratios of SNR shocks in which\ndust grains are heated and destroyed by collisions with plasma particles. For\nthe majority of SNRs, however, $R_{IRX,obs}$ values are either significantly\nsmaller or significantly larger than the theoretical ratios. The latter SNRs\nhave relatively low dust temperatures. We discuss how the natural and/or\nenvironmental properties of SNRs could have affected the IRX flux ratios and\nthe IRX morphology of these SNRs. We conclude that the SNRs with largest\n$R_{IRX,obs}$ are probably located in dense environment and that their IR\nemission is from dust heated by shock radiation rather than by collisions. Our\nresult suggests that the IRX flux ratio, together with dust temperature, can be\nused to infer the nature of unresolved SNRs in external galaxies." }, { "anchor": "Autonomous Gaussian decomposition of the Galactic Ring Survey. I. Global\n statistics and properties of the 13CO emission data: The analysis of large molecular line surveys of the Galactic plane is\nessential for our understanding of the gas kinematics on Galactic scales, in\nparticular its link with the formation and evolution of dense structures in the\ninterstellar medium. An approximation of the emission peaks with Gaussian\nfunctions allows for an efficient and straightforward extraction of useful\nphysical information contained in the shape and Doppler-shifted frequency of\nthe emission lines contained in these enormous data sets. In this work we\npresent an overview and first results of a Gaussian decomposition of the entire\nGalactic Ring Survey (GRS) 13CO (1-0) data that consists of about 2.3 million\nspectra. We performed the decomposition with the fully automated GaussPy+\nalgorithm and fitted about 4.6 million Gaussian components to the GRS spectra.\nWe discuss the statistics of the fit components and relations between the\nfitted intensities, velocity centroids, and velocity dispersions. We find that\nthe magnitude of the velocity dispersion values increase toward the inner\nGalaxy and around the Galactic midplane, which we speculate is partly due to\nthe influence of the Galactic bar and regions with higher non-thermal motions\nlocated in the midplane, respectively. We also use our decomposition results to\ninfer global properties of the gas emission and find that the number of fit\ncomponents used per spectrum is indicative for the amount of structure along\nthe line of sight. We find that the emission lines from regions located on the\nfar side of the Galaxy show increased velocity dispersion values, likely due to\nbeam averaging effects. We demonstrate how this trend has the potential to aid\nin characterising Galactic structure by disentangling emission that is\nbelonging to the nearby Aquila Rift molecular cloud from emission that is more\nlikely associated with the Perseus and Outer spiral arms.", "positive": "Compact Groups of Galaxies in Sloan Digital Sky Survey and LAMOST\n Spectral Survey. II. Dynamical Properties of Isolated and Embedded Groups: Compact groups (CGs) of galaxies appear to be the densest galaxy systems\ncontaining a few luminous galaxies in close proximity to each other, which have\na typical size of a few tens kilopacsec in observation. On the other hand, in\nthe modern hierarchical structure formation paradigm, galaxies are assembled\nand grouped in dark matter haloes, which have a typical size of a few hundreds\nof kiloparsec. Few studies have explored the physical connection between the\nobservation based CGs and halo model based galaxy groups to date. In this\nstudy, by matching the largest local CG catalog of Zheng & Shen (2020) to the\nhalo based group catalog of Yang et al. (2007), we find that the CGs are\nphysically heterogenous systems and can be mainly separated into two\ncategories, the isolated systems and those embedded in rich groups or clusters.\nBy examining the dynamical features of CGs, we find that the isolated CGs have\nsystematically lower dynamical masses than that of non-compact ones at the same\ngroup luminosity, indicating a more evolved stage of isolated CGs. On the other\nhand, the embedded CGs are mixtures of chance alignments in poor clusters and\nrecent infalling groups (sub-structures) of rich clusters." }, { "anchor": "RAiSE X: searching for radio galaxies in X-ray surveys: We model the X-ray surface brightness distribution of emission associated\nwith Fanaroff & Riley type-II radio galaxies. Our approach builds on the RAiSE\ndynamical model which describes broadband radio-frequency synchrotron evolution\nof jet-inflated lobes in a wide range of environments. The X-ray version of the\nmodel presented here includes: (1) inverse-Compton upscattering of cosmic\nmicrowave background radiation; (2) the dynamics of the shocked gas shell and\nassociated bremsstrahlung radiation; and (3) emission from the surrounding\nambient medium. We construct X-ray surface brightness maps for a mock catalogue\nof extended FR-IIs based on the technical characteristics of the eRosita\ntelescope. The integrated X-ray luminosity function at low redshifts\n($z\\leqslant1$) is found to strongly correlate with the density of the ambient\nmedium in all but the most energetic sources, whilst at high-redshift ($z>1$)\nthe majority of objects are dominated by inverse-Compton lobe emission due to\nthe stronger cosmic microwave background radiation. By inspecting our mock\nspatial brightness distributions, we conclude that any extended X-ray detection\ncan be attributed to AGN activity at redshifts $z\\geqslant1$. We compare the\nexpected detection rates of active and remnant high-redshift radio AGNs for\neRosita and LOFAR, and future more sensitive surveys. We find that a factor of\nten more remnants can be detected using X-ray wavelengths over radio\nfrequencies at $z>2.2$, increasing to a factor of 100 for redshifts $z>3.1$.", "positive": "[O~{\\small VI} from the SBs of the LMC: We have presented the observations of O {\\small VI} absorption at 1032 \\AA\\\ntowards 22 sightlines in 10 superbubbles (SBs) of the Large Magellanic Cloud\n(LMC) using the data obtained from the {\\em Far Ultraviolet Spectroscopic\nExplorer (FUSE)}. The estimated abundance of O {\\small VI} in the SBs varies\nfrom a minimum of (1.09 $\\pm$0.22)$\\times10^{14}$ atoms/cm$^{2}$ in SB N206 to\na maximum of (3.71$\\pm$0.23)$\\times10^{14}$ atoms/cm$^{2}$ in SB N70. We find\nabout a 46% excess in the abundance of O {\\small VI} in the SBs compared to the\nnon-SB lines of sight. Even inside a SB, O {\\small VI} column density (N(O\n{\\small VI})) varies by about a factor of 2 to 2.5. These data are useful in\nunderstanding the nature of the hot gas in SBs." }, { "anchor": "JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution\n studies: I. Survey overview and first results: JINGLE is a new JCMT legacy survey designed to systematically study the cold\ninterstellar medium of galaxies in the local Universe. As part of the survey we\nperform 850um continuum measurements with SCUBA-2 for a representative sample\nof 193 Herschel-selected galaxies with M*>10^9Msun, as well as integrated\nCO(2-1) line fluxes with RxA3m for a subset of 90 of these galaxies. The sample\nis selected from fields covered by the Herschel-ATLAS survey that are also\ntargeted by the MaNGA optical integral-field spectroscopic survey. The new JCMT\nobservations combined with the multi-wavelength ancillary data will allow for\nthe robust characterization of the properties of dust in the nearby Universe,\nand the benchmarking of scaling relations between dust, gas, and global galaxy\nproperties. In this paper we give an overview of the survey objectives and\ndetails about the sample selection and JCMT observations, present a consistent\n30 band UV-to-FIR photometric catalog with derived properties, and introduce\nthe JINGLE Main Data Release (MDR). Science highlights include the\nnon-linearity of the relation between 850um luminosity and CO line luminosity,\nand the serendipitous discovery of candidate z>6 galaxies.", "positive": "A WFC3 Grism Emission Line Redshift Catalog in the GOODS-South Field: We combine HST/WFC3 imaging and G141 grism observations from the CANDELS and\n3D-HST surveys to produce a catalog of grism spectroscopic redshifts for\ngalaxies in the CANDELS/GOODS-South field. The WFC3/G141 grism spectra cover a\nwavelength range of 1.1 0.6. The resulting spectra are visually inspected\nto identify emission lines and redshifts are determined using cross-correlation\nwith empirical spectral templates. To establish the accuracy of our redshifts,\nwe compare our results against high-quality spectroscopic redshifts from the\nliterature. Using a sample of 411 control galaxies, this analysis yields a\nprecision of sigma_NMAD=0.0028 for the grism-derived redshifts, which is\nconsistent with the accuracy reported by the 3D-HST team. Our final catalog\ncovers an area of 153 square arcmin and contains 1019 redshifts for galaxies in\nGOODS-S. Roughly 60% (608/1019) of these redshifts are for galaxies with no\npreviously published spectroscopic redshift. These new redshifts span a range\nof 0.677 < z < 3.456 and have a median redshift of z=1.282. The catalog\ncontains a total of 234 new redshifts for galaxies at z>1.5. In addition, we\npresent 20 galaxy pair candidates identified for the first time using the grism\nredshifts in our catalog, including four new galaxy pairs at z~2, nearly\ndoubling the number of such pairs previously identified." }, { "anchor": "The embedded cluster or association Trumpler 37 in IC1396: a search for\n evolutionary constraints: It is currently widely accepted that open star clusters and stellar\nassociations result from the evolution of embedded star clusters. Parameters\nsuch star formation efficiency, time-scale of gas removal and velocity\ndispersion can be determinants of their future as bound or unbound systems.\nFinding objects at an intermediate evolution state can provide constraints to\nmodel the embedded cluster evolution. In the HII region IC1396, Trumpler 37 is\nan extended young cluster that presents characteristics of an association. We\nemployed the Two Micron All Sky Survey (2MASS) photometry to analysing its\nstructure and stellar content, and determining its astrophysical parameters. We\nalso analysed 11 bright-rimmed clouds in IC1396 in order to search for young\ninfrared star clusters, and the background open star cluster Teutsch 74, to\nverify whether it has any contribution to the observed stellar density profile\nof Trumpler 37. The derived parameters and comparison with template objects\nfrom other studies lead us to conclude that Trumpler 37, rather than as a star\ncluster, will probably emerge from its molecular cloud as an OB association.", "positive": "Isolated Massive Star Formation in G28.20-0.05: We report high-resolution 1.3~mm continuum and molecular line observations of\nthe massive protostar G28.20-0.05 with ALMA. The continuum image reveals a\nring-like structure with 2,000~au radius, similar to morphology seen in\narchival 1.3~cm VLA observations. Based on its spectral index and associated\nH$30\\alpha$ emission, this structure mainly traces ionised gas. However, there\nis evidence for $\\sim30$~M$_{\\odot}$ of dusty gas near the main mm continuum\npeak on one side of the ring, as well as in adjacent regions within 3,000~au. A\nvirial analysis on scales of $\\sim$2,000~au from hot core line emission yields\na dynamical mass of $\\sim80\\:M_\\odot$. A strong velocity gradient in the\nH$30\\alpha$ emission is evidence for a rotating, ionized disk wind, which\ndrives a larger-scale molecular outflow. An infrared SED analysis indicates a\ncurrent protostellar mass of $m_*\\sim40\\:M_\\odot$ forming from a core with\ninitial mass $M_c\\sim300\\:M_\\odot$ in a clump with mass surface density of\n$\\Sigma_{\\rm cl}\\sim 0.8\\:{\\rm g\\:cm}^{-2}$. Thus the SED and other properties\nof the system can be understood in the context of core accretion models.\nStructure-finding analysis on the larger-scale continuum image indicates\nG28.20-0.05 is forming in a relatively isolated environment, with no other\nconcentrated sources, i.e., protostellar cores, above $\\sim 1\\:M_\\odot$ found\nfrom $\\sim$0.1 to 0.4~pc around the source. This implies that a massive star\ncan form in relative isolation and the dearth of other protostellar companions\nwithin the $\\sim1$~pc environs is a strong constraint on massive star formation\ntheories that predict the presence of a surrounding protocluster." }, { "anchor": "The final-parsec problem in non-spherical galaxies revisited: We consider the evolution of supermassive black hole binaries at the center\nof spherical, axisymmetric, and triaxial galaxies, using direct N-body\nintegrations as well as analytic estimates. We find that the rates of binary\nhardening exhibit a significant N-dependence in all the models, at least for N\nin the investigated range of 10^5<=N<=10^6. Binary hardening rates are also\nsubstantially lower than would be expected if the binary loss cone remained\nfull, as it would be if the orbits supplying stars to the binary were being\nefficiently replenished. The difference in binary hardening rates between the\nspherical and nonspherical models is less than a factor of two even in the\nsimulations with the largest N. By studying the orbital populations of our\nmodels, we conclude that the rate of supply of stars to the binary via draining\nof centrophilic orbits is indeed expected to be much lower than the\nfull-loss-cone rate, consistent with our simulations. We argue that the\nbinary's evolution in the simulations is driven in roughly equal amounts by\ncollisional and collisionless effects, even at the highest N-values currently\naccessible. While binary hardening rates would probably reach a limiting value\nfor large N, our results suggest that we cannot approach that rate with\ncurrently available algorithms and computing hardware. The extrapolation of\nresults from N-body simulations to real galaxies is therefore not\nstraightforward, casting doubt on recent claims that triaxiality or axisymmetry\nalone are capable of solving the final-parsec problem in gas-free galaxies.", "positive": "Young stellar cluster dilution near supermassive black holes: the impact\n of Vector Resonant Relaxation on neighbour separation: We investigate the rate of orbital orientation dilution of young stellar\nclusters in the vicinity of supermassive black holes. Within the framework of\nvector resonant relaxation, we predict the time evolution of the two-point\ncorrelation function of the stellar orbital plane orientations as a function of\ntheir initial angular separation and diversity in orbital parameters\n(semi-major axis, eccentricity). As expected, the larger the spread in initial\norientations and orbital parameters, the more efficient the dilution of a given\nset of co-eval stars, with a characteristic timescale set up by the coherence\ntime of the background potential fluctuations. A Markovian prescription which\nmatches numerical simulations allows us to efficiently probe the underlying\nkinematic properties of the unresolved nucleus when requesting consistency with\na given dilution efficiency, imposed by the observed stellar disc within the\none arcsecond of Sgr A*. As a proof of concept, we compute maps of constant\ndilution times as a function of the semi major axis cusp index and fraction of\nintermediate mass black holes in the old background stellar cluster. This\ncomputation suggests that vector resonant relaxation should prove useful in\nthis context since it impacts orientations on timescales comparable to the\nstars' age." }, { "anchor": "Simulated host galaxy analogs of high-z quasars observed with JWST: The hosts of two low-luminosity high-z quasars, J2255+0251 and J2236+0032,\nwere recently detected using JWST's NIRCam instrument. These represent the\nfirst high-z quasar host galaxy stellar detections and open a new window into\nstudying high-z quasars. We examine the implications of the measured properties\nof J2255+0251 and J2236+0032 within the context of the hydrodynamic simulation\nBlueTides at z = 6.5. We find that these observed quasars fall on the BlueTides\nstellar to black hole mass relation and have similar luminosities to the\nbrightest simulated quasars. We predict their star formation rates, estimating\napproximately $10^{2-3}$ $M_{\\odot}/ \\rm yr$ for both quasar hosts. J2255+0251\nand J2236+0032's host galaxy radii also fall within estimates of the radii of\nthe simulated host galaxies of similar luminosity quasars. We generate mock\nJWST NIRCam images of analogs to the observed quasars within BlueTides and\nperform a point source removal to illustrate both a qualitative and\nquantitative comparison of the measured and simulated radii and magnitudes. The\nquasar subtraction works well for similar luminosity quasars, and the recovered\nhost images are consistent with what was observed for J2255+0251 and\nJ2236+0032, further supporting the success of those observations. We also use\nour mock imaging pipeline to make predictions for the detection of J2255+0251\nand J2236+0032's hosts in upcoming JWST observations. We anticipate that the\nsimulation analogs of future high-z quasar host discoveries will allow us to\nmake accurate predictions of their properties beyond the capabilities of JWST.", "positive": "Galactic outflow rates in the EAGLE simulations: We present measurements of galactic outflow rates from the EAGLE suite of\ncosmological simulations. We find that gas is removed from the interstellar\nmedium (ISM) of central galaxies with a dimensionless mass loading factor that\nscales approximately with circular velocity as $V_{\\mathrm{c}}^{-3/2}$ in the\nlow-mass regime where stellar feedback dominates. Feedback from active galactic\nnuclei (AGN) causes an upturn in the mass loading for halo masses $> 10^{12} \\,\n\\mathrm{M_\\odot}$. We find that more gas outflows through the halo virial\nradius than is removed from the ISM of galaxies, particularly at low redshift,\nimplying substantial mass loading within the circum-galactic medium (CGM).\nOutflow velocities span a wide range at a given halo mass/redshift, and on\naverage increase positively with redshift and halo mass up to $M_{200} \\sim\n10^{12} \\, \\mathrm{M_\\odot}$. Outflows exhibit a bimodal flow pattern on\ncircum-galactic scales, aligned with the galactic minor axis. We present a\nnumber of like-for-like comparisons to outflow rates from other recent\ncosmological hydrodynamical simulations, and show that comparing the\npropagation of galactic winds as a function of radius reveals substantial\ndiscrepancies between different models. Relative to some other simulations,\nEAGLE favours a scenario for stellar feedback where agreement with the galaxy\nstellar mass function is achieved by removing smaller amounts of gas from the\nISM, but with galactic winds that then propagate and entrain ambient gas out to\nlarger radii." }, { "anchor": "Dissipative Dark Matter on FIRE: II. Observational signatures and\n constraints from local dwarf galaxies: We analyze the first set of cosmological baryonic zoom-in simulations of\ngalaxies in dissipative self-interacting dark matter (dSIDM). The simulations\nutilize the FIRE-2 galaxy formation physics with the inclusion of dissipative\ndark matter self-interactions modelled as a constant fractional energy\ndissipation ($f_{\\rm diss}=0.5$). In this paper, we examine the properties of\ndwarf galaxies with $M_{\\ast} \\sim 10^{5}\\operatorname{-}10^{9}\\,{\\rm\nM}_{\\odot}$ in both isolation and within Milky Way-mass hosts. For isolated\ndwarfs, we find more compact galaxy sizes and promotion of stellar/neutral gas\ndisk formation in dSIDM with $(\\sigma/m)\\leq 1\\,{\\rm cm^2\\,g^{-1}}$ but they\nare still consistent with observed galaxy sizes and masses. In addition, as a\nresult of the steeper central density profiles developed in dSIDM, the sub-kpc\ncircular velocities of isolated dwarfs in models with $(\\sigma/m)\\geq 0.1\\,{\\rm\ncm^2\\,g^{-1}}$ are enhanced by about a factor of two, which are still\nconsistent with the measured stellar velocity dispersions of Local Group dwarfs\nbut in tension with the HI rotation curves of more massive field dwarfs.\nMeanwhile, for satellites of the simulated Milky Way-mass hosts, the median\ncircular velocity profiles are marginally affected by dSIDM physics, but dSIDM\nmay help address the missing compact dwarf satellites in CDM. The number of\nsatellites is slightly enhanced in dSIDM, but the differences are small\ncompared with the large host-to-host variations. In conclusion, the dSIDM\nmodels with constant cross-section $(\\sigma/m) \\gtrsim 0.1\\,{\\rm cm^2\\,g^{-1}}$\n(assuming $f_{\\rm diss}=0.5$) are effectively ruled out in bright dwarfs\n($M_{\\rm halo}\\sim 10^{11}\\,{\\rm M}_{\\odot}$) by circular velocity constraints.\nHowever, models with lower effective cross-sections (at this halo mass/velocity\nscale) are still viable and can give rise to non-trivial observable signatures.", "positive": "Polarimetry of the Ly-alpha envelope of the radio-quiet quasar SDSS\n J124020.91+145535.6: The radio-quiet quasar SDSS J1240+1455 lies at a redshift of z=3.11, is\nsurrounded by a Ly-alpha blob (LAB), and is absorbed by a proximate damped\nLy-alpha system. In order to better define the morphology of the blob and\ndetermine its emission mechanism, we gathered deep narrow-band images isolating\nthe Ly-alpha line of this object in linearly polarized light. We provide a deep\nintensity image of the blob, showing a filamentary structure extending up to\n16'' (or ~122 physical kpc) in diameter. No significant polarization signal\ncould be extracted from the data, but 95% probability upper limits were defined\nthrough simulations. They vary between ~3% in the central 0.75'' disk (after\nsubtraction of the unpolarized quasar continuum) and ~10% in the 3.8-5.5''\nannulus. The low polarization suggests that the Ly-alpha photons are emitted\nmostly in situ, by recombination and de-excitation in a gas largely ionized by\nthe quasar ultraviolet light, rather than by a central source and scattered\nsubsequently by neutral hydrogen gas. This blob shows no detectable\npolarization signal, contrary to LAB1, a brighter and more extended blob that\nis not related to the nearby active galactic nucleus (AGN) in any obvious way,\nand where a significant polarization signal of about 18% was detected." }, { "anchor": "Exploring a new definition of the green valley and its implications: The distribution of galaxies on a colour-magnitude diagram reveals a\nbimodality, featuring a passively evolving red sequence and a star-forming blue\ncloud. The region between these two, the Green Valley (GV), represents a\nfundamental transition where quenching processes operate. We exploit an\nalternative definition of the GV using the 4,000 Angstrom break strength, an\nindicator that is more resilient than colour to dust attenuation. We compare\nand contrast our GV definition with the traditional one, based on\ndust-corrected colour, making use of data from the Sloan Digital Sky Survey.\nOur GV selection - that does not need a dust correction and thus does not carry\nthe inherent systematics - reveals very similar trends regarding nebular\nactivity (star formation, AGN, quiescence) to the standard dust-corrected\n$^{0.1}(g-r)$. By use of high SNR stacked spectra of the quiescent GV\nsubsample, we derive the simple stellar population (SSP) age difference across\nthe GV, a rough proxy of the quenching timescale ($\\Delta$t). We obtain an\nincreasing trend with velocity dispersion ($\\sigma$), from\n$\\Delta$t$\\sim$1.5Gyr at $\\sigma$=100km/s, up to 3.5Gyr at $\\sigma$=200km/s,\nfollowed by a rapid decrease in the most massive GV galaxies\n($\\Delta$t$\\sim$1Gyr at $\\sigma$=250km/s), suggesting two different modes of\nquenching, or the presence of an additional channel (rejuvenation).", "positive": "VVV CL001: Likely the Most Metal-Poor Surviving Globular Cluster in the\n Inner Galaxy: We present the first high-resolution abundance analysis of the globular\ncluster VVV~CL001, which resides in a region dominated by high interstellar\nreddening towards the Galactic Bulge. Using \\textit{H}-band spectra acquired by\nthe Apache Point Observatory Galactic Evolution Experiment (APOGEE), we\nidentified two potential members of the cluster, and estimate from their Fe I\nlines that the cluster has an average metallicity of [Fe/H] = $-2.45$ with an\nuncertainty due to systematics of 0.24 dex. We find that the light-(N),\n$\\alpha$-(O, Mg, Si), and Odd-Z (Al) elemental abundances of the stars in\nVVV~CL001 follow the same trend as other Galactic metal-poor globular clusters.\nThis makes VVV~CL001 possibly the most metal-poor globular cluster identified\nso far within the Sun's galactocentric distance and likely one of the most\nmetal-deficient clusters in the Galaxy after ESO280-SC06. Applying statistical\nisochrone fitting, we derive self-consistent age, distance, and reddening\nvalues, yielding an estimated age of $11.9^{+3.12}_{-4.05}$ Gyr at a distance\nof $8.22^{+1.84}_{-1.93}$ kpc, revealing that VVV~CL001 is also an old GC in\nthe inner Galaxy. The Galactic orbit of VVV~CL001 indicates that this cluster\nlies on a halo-like orbit that appears to be highly eccentric. Both chemistry\nand dynamics support the hypothesis that VVV~CL001 could be an ancient fossil\nrelic left behind by a massive merger event during the early evolution of the\nGalaxy, likely associated with either the Sequoia or the\n\\textit{Gaia}-Enceladus-Sausage structures." }, { "anchor": "The age-kinematical features in the Milky Way outer disk: We derive the mean velocity components at various Galactocentric radii from 8\nto 14 kpc using about 40,000 red clump stars observed in the LAMOST survey. We\nfind that the vertical bulk motion for younger red clump stars are\nsignificantly larger than that for the older red clump stars. This is likely\nthe kinematical feature of the Galactic warp around its line-of-node, which is\nlocated close to the Galactic anti-center region. It is evident that the warp\nare mainly contributed by the younger stars rather than the older stars. The\nage variation in the vertical kinematics favors a formation scenario where the\nGalactic warp is originated from infalling misaligned gas.", "positive": "Interstellar and circumstellar fullerenes: Fullerenes are a particularly stable class of carbon molecules in the shape\nof a hollow sphere or ellipsoid that might be formed in the outflows of carbon\nstars. Once injected into the interstellar medium (ISM), these stable species\nsurvive and are thus likely to be widespread in the Galaxy where they\ncontribute to interstellar extinction, heating processes, and complex chemical\nreactions. In recent years, the fullerene species C60 (and to a lesser extent\nC70) have been detected in a wide variety of circumstellar and interstellar\nenvironments showing that when conditions are favourable, fullerenes are formed\nefficiently. Fullerenes are the first and only large aromatics firmly\nidentified in space. The detection of fullerenes is thus crucial to provide\nclues as to the key chemical pathways leading to the formation of large complex\norganic molecules in space, and offers a great diagnostic tool to describe the\nenvironment in which they reside. Since fullerenes share many physical\nproperties with PAHs, understanding how fullerenes form, evolve and respond to\ntheir physical environment will yield important insights into one of the\nlargest reservoirs of organic material in space. In spite of all these\ndetections, many questions remain about precisely which members of the\nfullerene family are present in space, how they form and evolve, and what their\nexcitation mechanism is. We present here an overview of what we know from\nastronomical observations of fullerenes in these different environments, and\ndiscuss current thinking about the excitation process. We highlight the various\nformation mechanisms that have been proposed, discuss the physical conditions\nconducive to the formation and/or detection of fullerenes in carbon stars, and\ntheir possible connection to PAHs, HACs and other dust features." }, { "anchor": "Major mergers are not significant drivers of star formation or\n morphological transformation around the epoch of peak cosmic star formation: We investigate the contribution of major mergers (mass ratios $>1:5$) to\nstellar mass growth and morphological transformations around the epoch of peak\ncosmic star formation ($z\\sim2$). We visually classify a complete sample of\nmassive (M $>$ 10$^{10}$M$_{\\odot}$) galaxies at this epoch, drawn from the\nCANDELS survey, into late-type galaxies, major mergers, spheroids and disturbed\nspheroids which show morphological disturbances. Given recent simulation work,\nwhich indicates that recent ($<$0.3-0.4 Gyr) major-merger remnants exhibit\nclear tidal features in such images, we use the fraction of disturbed spheroids\nto probe the role of major mergers in driving morphological transformations.\nThe percentage of blue spheroids (i.e. with ongoing star formation) that show\nmorphological disturbances is only 21 $\\pm$ 4%, indicating that major mergers\nare not the dominant mechanism for spheroid creation at $z\\sim2$ - other\nprocesses, such as minor mergers or cold accretion are likely to be the main\ndrivers of this process. We also use the rest-frame U-band luminosity as a\nproxy for star formation to show that only a small fraction of the star\nformation budget ($\\sim$3%) is triggered by major mergers. Taken together, our\nresults show that major mergers are not significant drivers of galaxy evolution\nat $z\\sim2$.", "positive": "Cosmic evolution of radio-excess AGNs in quiescent and star-forming\n galaxies across $0 < z < 4$: Recent deep and wide radio surveys extend the studies for radio-excess active\ngalactic nuclei (radio-AGNs) to lower luminosities and higher redshifts,\nproviding new insights into the abundance and physical origin of radio-AGNs.\nHere we focus on the cosmic evolution, physical properties and AGN-host galaxy\nconnections of radio-AGNs selected from a sample of ~ 500,000 galaxies at 0 < z\n< 4 in GOODS-N, GOODS-S, and COSMOS fields. Combining deep radio data with\nmulti-band, de-blended far-infrared (FIR) and sub-millimeter data, we identify\n1162 radio-AGNs through radio excess relative to the FIR-radio relation. We\nstudy the cosmic evolution of 1.4 GHz radio luminosity functions (RLFs) for\nstar-forming galaxies (SFGs) and radio-AGNs, which are well described by a pure\nluminosity evolution of $L_*\\propto (1+z)^{-0.31z+3.41}$ and a pure density\nevolution of $\\Phi_*\\propto (1+z)^{-0.80z+2.88}$, respectively. We derive the\nturnover luminosity above which the number density of radio-AGNs surpasses that\nof SFGs. This crossover luminosity increases as increasing redshift, from\n$10^{22.9}$ W Hz$^{-1}$ at z ~ 0 to $10^{25.2}$ W Hz$^{-1}$ at z ~ 4. At full\nredshift range (0 < z < 4), we further derive the probability ($p_{radio}$) of\nSFGs and quiescent galaxies (QGs) hosting a radio-AGN as a function of stellar\nmass ($M_*$), radio luminosity ($L_R$), and redshift (z), which yields\n$p_{radio}\\propto (1+z)^{3.54}M_*^{1.02}L_R^{-0.90}$ for SFGs, and\n$p_{radio}\\propto (1+z)^{2.38}M_*^{1.39}L_R^{-0.60}$ for QGs, respectively. It\nindicates that radio-AGNs in QGs prefer to reside in more massive galaxies with\nlarger $L_R$ than those in SFGs, and radio-AGN fraction increases towards\nhigher redshift in both SFGs and QGs with a more rapid increase in SFGs.\nFurther, we find that the radio-AGN fraction depends on accretion states of BHs\nand redshift in SFGs, while in QGs it also depends on BH (or galaxy) mass." }, { "anchor": "On the polytropic Bondi accretion in two-component galaxy models with a\n central massive BH: In many investigations involving accretion on a central point mass, ranging\nfrom observational studies to cosmological simulations, including\nsemi-analytical modelling, the classical Bondi accretion theory is the standard\ntool widely adopted. Previous works generalised the theory to include the\neffects of the gravitational field of the galaxy hosting a central black hole,\nand of electron scattering in the optically thin limit. Here we apply this\nextended Bondi problem, in the general polytropic case, to a class of new\ntwo-component galaxy models recently presented. In these models, a Jaffe\nstellar density profile is embedded in a dark matter halo such that the total\ndensity distribution follows a $r^{-3}$ profile at large radii; the stellar\ndynamical quantities can be expressed in a fully analytical way. The\nhydrodynamical properties of the flow are set by imposing that the gas\ntemperature at infinity is proportional to the virial temperature of the\nstellar component. The isothermal and adiabatic (monoatomic) cases can be\nsolved analytically, in the other cases we explore the accretion solution\nnumerically. As non-adiabatic accretion inevitably leads to an exchange of heat\nwith the ambient, we also discuss some important thermodynamical properties of\nthe polytropic Bondi accretion, and provide the expressions needed to compute\nthe amount of heat exchanged with the environment, as a function of radius. The\nresults can be useful for the subgrid treatment of accretion in numerical\nsimulations, as well as for the interpretation of observational data.", "positive": "Testing the Modern Merger Hypothesis via the Assembly of Massive Blue\n Elliptical Galaxies in the Local Universe: The modern merger hypothesis offers a method of forming a new elliptical\ngalaxy through merging two equal-mass, gas-rich disk galaxies fuelling a\nnuclear starburst followed by efficient quenching and dynamical stabilization.\nA key prediction of this scenario is a central concentration of young stars\nduring the brief phase of morphological transformation from highly-disturbed\nremnant to new elliptical galaxy. To test this aspect of the merger hypothesis,\nwe use integral field spectroscopy to track the stellar Balmer absorption and\n4000\\AA\\ break strength indices as a function of galactic radius for 12 massive\n(${\\rm M_{*}}\\ge10^{10}{\\rm M_{\\odot}}$), nearby (${\\rm z}\\le0.03$),\nvisually-selected plausible new ellipticals with blue-cloud optical colours and\nvarying degrees of morphological peculiarities. We find that these index values\nand their radial dependence correlate with specific morphological features such\nthat the most disturbed galaxies have the smallest 4000\\AA\\ break strengths and\nthe largest Balmer absorption values. Overall, two-thirds of our sample are\ninconsistent with the predictions of the modern merger hypothesis. Of these\neight, half exhibit signatures consistent with recent minor merger\ninteractions. The other half have star formation histories similar to local,\nquiescent early-type galaxies. Of the remaining four galaxies, three have the\nstrong morphological disturbances and star-forming optical colours consistent\nwith being remnants of recent, gas-rich major mergers, but exhibit a weak,\ncentral burst consistent with forming $\\sim5\\%$ of their stars. The final\ngalaxy possesses spectroscopic signatures of a strong, centrally-concentrated\nstarburst and quiescent core optical colours indicative of recent quenching\n(i.e., a post-starburst signature) as prescribed by the modern merger\nhypothesis." }, { "anchor": "High-redshift Narrow-line Seyfert 1 Galaxies: A Candidate Sample: The study of narrow-line Seyfert 1 galaxies (NLS1s) is now mostly limited to\nlow redshift ($z<0.8$) because their definition requires the presence of the\nH$\\beta$ emission line, which is redshifted out of the spectral coverage of\nmajor ground-based spectroscopic surveys at $z>0.8$. We studied the correlation\nbetween the properties of H$\\beta$ and Mg II lines of a large sample of SDSS\nDR14 quasars to find high-$z$ NLS1 candidates. Based on the strong correlation\nof $\\mathrm{FWHM(MgII)=(0.880\\pm 0.005) \\times FWHM(H\\beta)+ (0.438\\pm0.018)}$,\nwe present a sample of high-$z$ NLS1 candidates having FWHM of Mg II $<$ 2000\nkm s$^{-1}$. The high-$z$ sample contains 2684 NLS1s with redshift $z=0.8-2.5$\nwith a median logarithmic bolometric luminosity of $46.16\\pm0.42$ erg s$^{-1}$,\nlogarithmic black hole mass of $8.01\\pm0.35 M_{\\odot}$, and logarithmic\nEddington ratio of $0.02\\pm0.27$. The fraction of radio-detected high-$z$ NLS1s\nis similar to that of the low-$z$ NLS1s and SDSS DR14 quasars at a similar\nredshift range, and their radio luminosity is found to be strongly correlated\nwith their black hole mass.", "positive": "The LOFAR Two-metre Sky Survey: the radio view of the cosmic star\n formation history: We present a detailed study of the cosmic star formation history over $90$\nper cent of cosmic time ($0\\lesssim z\\lesssim4$), using deep, radio continuum\nobservations that probe star formation activity independent of dust. The Low\nFrequency Array Two Metre Sky Survey has imaged three well-studied\nextragalactic fields, Elais-N1, Bo\\\"otes and the Lockman Hole, reaching\n$\\sim20\\,\\mu\\rm{Jy/beam}$ rms sensitivity at $150\\,\\rm{MHz}$. The availability\nof high-quality ancillary data from ultraviolet to far-infrared wavelengths has\nenabled accurate photometric redshifts and the robust separation of\nradio-bright AGN from their star-forming counterparts. We capitalise on this\nunique combination of deep, wide fields and robustly-selected star-forming\ngalaxies to construct radio luminosity functions and derive the cosmic star\nformation rate density. We carefully constrain and correct for scatter in the\n$L_{150\\,\\rm{MHz}}-\\rm{SFR}$ relation, which we find to be $\\sim0.3\\,\\rm{dex}$.\nOur derived star formation rate density lies between previous measurements at\nall redshifts studied. We derive higher star formation rate densities between\n$z\\sim0$ and $z\\sim3$ than are typically inferred from short wavelength\nemission; at earlier times, this discrepancy is reduced. Our measurements are\ngenerally in good agreement with far-infrared and radio-based studies, with\nsmall offsets resulting from differing star formation rate calibrations." }, { "anchor": "Spatially Resolving Substructures within the Massive Envelope around an\n Intermediate-mass Protostar: MMS 6/OMC-3: With the Submillimeter Array, the brightest (sub)millimeter continuum source\nin the OMC-2/3 region, MMS 6, has been observed in the 850 um continuum\nemission with approximately 10 times better angular resolution than previous\nstudies (~0.3\"; ~120 AU at Orion). The deconvolved size, the mass, and the\ncolumn density of MMS 6-main are estimated to be 0.32\"x0.29\" (132 AUx120 AU),\n0.29 Mo, and 2.1x10^{25} cm^{-2}, respectively. The estimated extremely high\nmean number density, 1.5x10^{10} cm^{-3}, suggests that MMS 6-main is likely\noptically thick at 850 um. We compare our observational data with three\ntheoretical core models: prestellar core, protostellar core + disk-like\nstructure, and first adiabatic core. These comparisons clearly show that the\nobservational data cannot be modeled as a simple prestellar core with a gas\ntemperature of 20 K. A self-luminous source is necessary to explain the\nobserved flux density in the (sub)millimeter wavelengths. Our recent detection\nof a very compact and energetic outflow in the CO (3-2) and HCN (4-3) lines,\nsupports the presence of a protostar. We suggest that MMS 6 is one of the first\ncases of an intermediate mass protostellar core at an extremely young stage. In\naddition to the MMS 6-main peak, we have also spatially resolved a number of\nspiky structures and sub-clumps, distributed over the central 1000 AU. The\nmasses of these sub-clumps are estimated to be 0.066-0.073 Mo, which are on the\norder of brown dwarf masses. Higher angular resolution and higher sensitivity\nobservations with ALMA and EVLA will reveal the origin and nature of these\nstructures such as whether they are originated from fragmentations, spiral\narms, or inhomogeneity within the disk-like structures/envelope.", "positive": "Which galaxy property is the best gauge of the oxygen abundance?: We present an extensive exploration of the impact of 29 physical parameters\nin the oxygen abundance for a sample of 299 star-forming galaxies extracted\nfrom the extended CALIFA sample. We corroborate that the stellar mass is the\nphysical parameter that better traces the observed oxygen abundance (i.e., the\nmass-metallicity relation, MZR), while other physical parameters could play a\npotential role in shaping this abundance, but with a lower significant impact.\nWe find that the functional form that best describes the MZR is a third-order\npolynomial function. From the residuals between this best functional form and\nthe MZR, we find that once considered the impact of the mass in the oxygen\nabundance, the other physical parameters do not play a significant secondary\nrole in shaping the oxygen abundance in these galaxies (including the gas\nfraction or the star formation rate). Our analysis suggests that the origin of\nthe MZR is related to the chemical enrichment evolution of the interstellar\nmedium due, most likely, to the build-up of stellar mass in these star-forming\ngalaxies." }, { "anchor": "The integrated galaxy-wide stellar initial mass function over the radial\n acceleration range of early-type galaxies: The observed radial accelerations of 462 Early-type galaxies (ETGs) at their\nhalf-mass radii are discussed. They are compared to the baryonic masses of the\nsame galaxies, which are derived from theoretical expectations for their\nstellar populations and cover a range from $\\approx 10^4 \\, {\\rm M}_{\\odot}$ to\n$\\approx 10^{11} \\, {\\rm M}_{\\odot}$. Both quantities are plotted against each\nother, and it is tested whether they lie (within errors) along theoretical\nradial acceleration relations (RARs). We choose the Newtonian RAR and two\nMilgromian, or MONDian RARs. At low radial accelerations (corresponding to low\nmasses), the Newtonian RAR fails without non-baryonic dark matter, but the two\nMONDian ones may work, provided moderate out-of-equilibrium dynamics in some of\nthe low-mass ETGs. However all three RARs fail at high accelerations\n(corresponding to high masses) if all ETGs have formed their stellar\npopulations with the canonical stellar initial mass function (IMF). A much\nbetter agreement with the observations can however be accomplished, if the\ntheory of the integrated galaxy-wide stellar initial mass functions (IGIMFs) is\nused instead. This is because the IGIMF-theory predicts the formation of an\noverabundance of stellar remnants during the lifetime of the massive ETGs. Thus\ntheir baryonic masses today are higher than they would be if the ETGs had\nformed with a canonical IMF. Also the masses of the stellar-mass black holes\nshould be rather high, which would mean that most of them probably formed when\nthe massive ETGs were not as metal-enriched as they are today. The\nIGIMF-approach confirms downsizing.", "positive": "Atomic Shocks in the Outflow of L1551 IRS 5 Identified with\n SOFIA-upGREAT Observations of [OI]: We present velocity resolved SOFIA/upGREAT observations of [OI] and [CII]\nlines toward a Class I protostar, L1551 IRS 5, and its outflows. The SOFIA\nobservations detect [OI] emission toward only the protostar and [CII] emission\ntoward the protostar and the red-shifted outflow. The [OI] emission has a width\nof $\\sim$100 km s$^{-1}$ only in the blue-shifted velocity, suggesting an\norigin in shocked gas. The [CII] lines are narrow, consistent with an origin in\na photodissociation region. Differential dust extinction from the envelope due\nto the inclination of the outflows is the most likely cause of the missing\nred-shifted [OI] emission. Fitting the [OI] line profile with two Gaussian\ncomponents, we find one component at the source velocity with a width of\n$\\sim$20 km s$^{-1}$ and another extremely broad component at -30 km s$^{-1}$\nwith a width of 87.5 km s$^{-1}$, the latter of which has not been seen in\nL1551 IRS 5. The kinematics of these two components resemble cavity shocks in\nmolecular outflows and spot shocks in jets. Radiative transfer calculations of\nthe [OI], high-J CO, and H$_2$O lines in the cavity shocks indicate that [OI]\ndominates the oxygen budget, making up more than 70% of the total gaseous\noxygen abundance and suggesting [O]/[H] of $\\sim$1.5$\\times$10$^{-4}$.\nAttributing the extremely broad [OI] component to atomic winds, we estimate the\nintrinsic mass loss rate of (1.3$\\pm$0.8)$\\times$ 10$^{-6}$ M$_{\\odot}$\nyr$^{-1}$. The intrinsic mass loss rates derived from low-J CO, [OI], and HI\nare similar, supporting the model of momentum-conserving outflows, where the\natomic wind carries most momentum and drives the molecular outflows." }, { "anchor": "A lower bound on the Milky Way mass from general phase-space\n distribution function models: We model the phase-space of the kinematic tracers using general, smooth\ndistribution functions to derive a conservative lower bound on the total mass\nwithin 150-200 kpc.\n By approximating the potential as Keplerian, the phase-space distribution can\nbe simplified to that of a smooth distribution of energies and eccentricities.\nOur approach naturally allows for calculating moments of the distribution\nfunction, such as the radial profile of the orbital anisotropy. We construct a\nfamily of phase-spaces with the resulting radial velocity dispersion\noverlapping with that of distant kinematic tracers, while making no assumptions\nabout the density of the tracers and the radial profile of the velocity\nanisotropy (beta).\n While there is no apparent upper bound for the Milky Way mass, at least as\nlong as only the radial motions are concerned, we find a sharp lower bound for\nthe mass that is small. In particular, a mass value of $2.4 \\times 10^{11}$ of\nsolar masses, is still consistent with the dispersion profile at larger radii.\n Compared with much greater mass values in the literature, this result shows\nthat determining the Milky Way mass is strongly model dependent. We expect a\nsimilar reduction of mass estimates in models assuming more realistic mass\nprofiles.", "positive": "The Multidimensional Milky Way: Studying our Galaxy, the Milky Way (MW), gives us a close-up view of the\ninterplay between cosmology, dark matter, and galaxy formation. In the next\ndecade our understanding of the MW's dynamics, stellar populations, and\nstructure will undergo a revolution thanks to planned and proposed astrometric,\nspectroscopic and photometric surveys, building on recent advances by the Gaia\nastrometric survey. Together, these new efforts will measure three-dimensional\npositions and velocities and numerous chemical abundances for stars to the MW's\nedge and well into the Local Group, leading to a complete multidimensional view\nof our Galaxy. Studies of the multidimensional Milky Way beyond the Gaia\nfrontier---from the edge of the Galactic disk to the edge of our Galaxy's dark\nmatter halo---will unlock new scientific advances across astrophysics, from\nconstraints on dark matter to insights into galaxy formation." }, { "anchor": "Enhanced Extreme Mass Ratio Inspiral Rates into Intermediate Mass Black\n Holes: Extreme mass ratio inspirals (EMRIs) occur when stellar-mass compact objects\nbegin a gravitational wave (GW) driven inspiral into massive black holes. EMRI\nwaveforms can precisely map the surrounding spacetime, making them a key target\nfor future space-based GW interferometers such as {\\it LISA}, but their event\nrates and parameters are massively uncertain. One of the largest uncertainties\nis the ratio of true EMRIs (which spend at least thousands of orbits in the\n{\\it LISA} band) and direct plunges, which are in-band for at most a handful of\norbits and are not detectable in practice. In this paper, we show that the\ntraditional dichotomy between EMRIs and plunges -- EMRIs originate from small\nsemimajor axes, plunges from large -- does not hold for intermediate-mass black\nholes with masses $M_\\bullet \\lesssim 10^5 M_\\odot$. In this low-mass regime, a\nplunge always has an $\\mathcal{O}(1)$ probability of failing and transitioning\ninto a novel ``cliffhanger'' EMRI. Cliffhanger EMRIs are more easily produced\nfor larger stellar-mass compact objects, and are less likely for smaller ones.\nThis new EMRI production channel can dominate volumetric EMRI rates\n$\\dot{n}_{\\rm EMRI}$ if intermediate-mass black holes are common in dwarf\ngalactic nuclei, potentially increasing $\\dot{n}_{\\rm EMRI}$ by an order of\nmagnitude.", "positive": "How Cosmic Rays Mediate the Evolution of the Interstellar Medium: We explore the impact of diffusive cosmic rays (CRs) on the evolution of the\ninterstellar medium (ISM) under varying assumptions of supernova explosion\nenvironment. In practice, we systematically vary the relative fractions of\nsupernovae (SN) occurring in star-forming high-density gas and those occurring\nin random locations decoupled from star-forming gas to account for SN from\nrun-away stars or explosions in regions that have been cleared by prior SN,\nstellar winds, or radiation. We explore various mixed models by adjusting these\nfractions relative to each other. We find that in the simple system of a\nperiodic stratified gas layer the ISM structure will evolve to one of two\nsolutions: a \"peak driving\" state where warm gas is volume filling or a\n\"thermal runaway\" state where hot gas is volume filling. CR pressure and\ntransport are important factors that strongly influence the solution state the\nISM reaches and have the ability to flip the ISM between solutions. Observable\nsignatures such as gamma ray emission and HI gas are explored. We find that\ngamma ray luminosity from pion decay is largely consistent with observations\nfor a range of model parameters. The thickness of the HI gas layer may be too\ncompact, however, this may be due to a large cold neutral fraction of midplane\ngas. The volume fraction of hot gas evolves to stable states in both solutions,\nbut neither settles to a Milky Way-like configuration, suggesting that\nadditional physics which is omitted here (e.g. a cosmological circum-galactic\nmedium, radiation transport, or spectrally resolved and spatially varying CR\ntransport) may be required." }, { "anchor": "Color gradients along the quiescent galaxy sequence: clues to quenching\n and structural growth: This Letter examines how the sizes, structures, and color gradients of\ngalaxies change along the quiescent sequence. Our sample consists of ~400\nquiescent galaxies at $1.0\\le z\\le2.5$ and $10.1 \\le \\log{M_*/M_\\odot}\\le11.6$\nin three CANDELS fields. We exploit deep multi-band HST imaging to derive\naccurate mass profiles and color gradients, then use an empirical calibration\nfrom rest-frame UVJ colors to estimate galaxy ages. We find that -- contrary to\nprevious results -- the youngest quiescent galaxies are not significantly\nsmaller than older quiescent galaxies at fixed stellar mass. These\n`post-starburst' galaxies only appear smaller in half-light radii because they\nhave systematically flatter color gradients. The strength of color gradients in\nquiescent galaxies is a clear function of age, with older galaxies exhibiting\nstronger negative color gradients (i.e., redder centers). Furthermore, we find\nthat the central mass surface density $\\Sigma_1$ is independent of age at fixed\nstellar mass, and only weakly depends on redshift. This finding implies that\nthe central mass profiles of quiescent galaxies do not significantly change\nwith age; however, we find that older quiescent galaxies have additional mass\nat large radii. Our results support the idea that building a massive core is a\nnecessary requirement for quenching beyond $z=1$, and indicate that\npost-starburst galaxies are the result of a rapid quenching process that\nrequires structural change. Furthermore, our observed color gradient and mass\nprofile evolution supports a scenario where quiescent galaxies grow inside-out\nvia minor mergers.", "positive": "Dynamical Friction in a magnetized gas: When a gravitating point mass moves subsonically through a magnetized and\nisothermal medium, the dynamical structure of the flow is studied far from the\nmass using a perturbation analysis. Analytical solutions for the first-order\ndensity and the velocity perturbations are presented. Validity of our solutions\nis restricted to the cases where the Alfven velocity in the ambient medium is\nless than the accretor's velocity. The density field is less dense because of\nthe magnetic effects according to the solutions and the dynamical friction\nforce becomes lower as the strength of the magnetic field increases." }, { "anchor": "The Impact of Cosmic Rays on Thermal and Hydrostatic Stability in\n Galactic Halos: We investigate how cosmic rays (CRs) affect thermal and hydrostatic stability\nof circumgalactic (CGM) gas, in simulations with both CR streaming and\ndiffusion. Local thermal instability can be suppressed by CR-driven entropy\nmode propagation, in accordance with previous analytic work. However, there is\nonly a narrow parameter regime where this operates, before CRs overheat the\nbackground gas. As mass dropout from thermal instability causes the background\ndensity and hence plasma $\\beta \\equiv P_g/P_B$ to fall, the CGM becomes\nglobally unstable. At the cool disk to hot halo interface, a sharp drop in\ndensity boosts Alfven speeds and CR gradients, driving a transition from\ndiffusive to streaming transport. CR forces and heating strengthen, while\ncountervailing gravitational forces and radiative cooling weaken, resulting in\na loss of both hydrostatic and thermal equilibrium. In lower $\\beta$ halos, CR\nheating drives a hot, single-phase diffuse wind with velocities $v \\propto\n(t_\\mathrm{heat}/t_\\mathrm{ff})^{-1}$, which exceeds the escape velocity when\n$t_\\mathrm{heat}/t_\\mathrm{ff} \\lesssim 0.4$. In higher $\\beta$ halos, CR\nforces drive multi-phase winds with cool, dense fountain flows and significant\nturbulence. These flows are CR dominated due to \"trapping\" of CRs by weak\ntransverse B-fields, and have the highest mass loading factors. Thus, local\nthermal instability can result in winds or fountain flows where either the heat\nor momentum input of CRs dominates.", "positive": "Predicting emission line fluxes and number counts of distant galaxies\n for cosmological surveys: We estimate the number counts of line emitters at high redshift and their\nevolution with cosmic time based on a combination of photometry and\nspectroscopy. We predict the H$\\alpha$, H$\\beta$, [OII], and [OIII] line fluxes\nfor more than $35,000$ galaxies down to stellar masses of $\\sim10^9$\n$M_{\\odot}$ in the COSMOS and GOODS-S fields, applying standard conversions and\nexploiting the spectroscopic coverage of the FMOS-COSMOS survey at $z\\sim1.55$\nto calibrate the predictions. We calculate the number counts of H$\\alpha$,\n[OII], and [OIII] emitters down to fluxes of $1\\times10^{-17}$ erg cm$^{-2}$\ns$^{-1}$ in the range $1.4 < z < 1.8$ covered by the FMOS-COSMOS survey. We\nmodel the time evolution of the differential and cumulative H$\\alpha$ counts,\nsteeply declining at the brightest fluxes. We expect $\\sim9,300-9,700$ and\n$\\sim2,300-2,900$ galaxies deg$^{-2}$ for fluxes $\\geq1\\times10^{-16}$ and\n$\\geq2\\times10^{-16}$ erg cm$^{-2}$ s$^{-1}$ over the range $0.910.5$) between redshifts 0.1 and 0.8 as a function\nof host stellar mass, redshift, morphology and satellite luminosity. Exploiting\nthe depth and resolution of the COSMOS HST images, we detect satellites up to\neight magnitudes fainter than the host galaxies and as close as 0.3 (1.4)\narcseconds (kpc). Describing the number density profile of satellite galaxies\nto be a projected power law such that $P(R)\\propto R^{\\rpower}$, we find\n$\\rpower=-1.1\\pm 0.3$. We find no dependency of $\\rpower$ on host stellar mass,\nredshift, morphology or satellite luminosity. Satellites of early-type hosts\nhave angular distributions that are more flattened than the host light profile\nand are aligned with its major axis. No significant average alignment is\ndetected for satellites of late-type hosts. The number of satellites within a\nfixed magnitude contrast from a host galaxy is dependent on its stellar mass,\nwith more massive galaxies hosting significantly more satellites. Furthermore,\nhigh-mass late-type hosts have significantly fewer satellites than early-type\ngalaxies of the same stellar mass, likely a result of environmental\ndifferences. No significant evolution in the number of satellites per host is\ndetected. The cumulative luminosity function of satellites is qualitatively in\ngood agreement with that predicted using subhalo abundance matching techniques.\nHowever, there are significant residual discrepancies in the absolute\nnormalization, suggesting that properties other than the host galaxy luminosity\nor stellar mass determine the number of satellites." }, { "anchor": "Beyond Gaia DR3: Tracing the [$\u03b1$/M]-[M/H] bimodality from the\n inner to the outer Milky Way disc with Gaia-RVS and convolutional neural\n networks: In June 2022, Gaia DR3 has provided the astronomy community with about one\nmillion spectra from the Radial Velocity Spectrometer (RVS) covering the CaII\ntriplet region. However, one-third of the published spectra have 15~6. Our results\nsuggest that UV bright galaxies at high-z such as Lyman break galaxies can be\nLyman continuum leakers and that their contribution to cosmic reionization may\nbe underestimated." }, { "anchor": "The VANDELS survey: the relation between UV continuum slope and stellar\n metallicity in star-forming galaxies at z~3: The estimate of stellar metallicities (Z*) of high-z galaxies are of\nparamount importance in order to understand the complexity of dust effects and\nthe reciprocal interrelations among stellar mass, dust attenuation, stellar\nage, and metallicity. Benefiting from uniquely deep FUV spectra of >500\nstar-forming galaxies at redshifts 2}\\,20$), star-forming ($\\rm\nsSFR\\,{>}\\,10^{-10}\\, \\rm yr^{-1}$), gas-rich ($f_{\\rm gas}\\,{>}\\,0.6$) and\ndisc-dominated ($\\rm B/T\\,{<}\\,0.7$) \\textit{low-mass galaxies} of stellar\nmasses $10^8\\,{-}\\,10^9 M_{\\odot}$. However, these properties are\nindistinguishable from those of galaxies harboring single massive black holes\nwith comparable mass, making difficult the selection of LISA hosts among the\nwhole population of low-mass galaxies. Motivated by this, we explore the\npossibility of using merger signatures to select LISA hosts. We find that\n40-80% of the galaxies housing LISA MBHBs display merger features related to\nthe interaction which brought the secondary MBH to the galaxy. Despite this,\naround 60% of dwarf galaxies placed in the surroundings of the LISA hosts will\nshow such kind of features as well, challenging the unequivocal detection of\nLISA hosts through the search of merger signatures. Consequently, the detection\nof an electromagnetic transient associated with the MBHB merger will be vital\nto pinpoint the star-forming dwarf galaxy where these binary systems evolve and\ncoalesce.", "positive": "Suppression of H2-cooling in protogalaxies aided by trapped Ly\u03b1\n cooling radiation: We study the thermal evolution of UV-irradiated atomic cooling haloes using\nhigh-resolution three-dimensional hydrodynamic simulations. We consider the\neffect of H^- photodetachment by Ly{\\alpha} cooling radiation trapped in the\noptically-thick cores of three such haloes, a process which has not been\nincluded in previous simulations. H^- is a precursor of molecular hydrogen, and\ntherefore, its destruction can diminish the H2 abundance and cooling. Using a\nsimple high-end estimate for the trapped Ly{\\alpha} energy density, we find\nthat H^- photodetachment by Ly{\\alpha} decreases the critical UV flux for\nsuppressing H2-cooling by up to a factor of \\approx 5. With a more conservative\nestimate of the Ly{\\alpha} energy density, we find the critical flux is\ndecreased only by ~15-50 percent. Our results suggest that Ly{\\alpha} radiation\nmay have an important effect on the thermal evolution of UV-irradiated haloes,\nand therefore on the potential for massive black hole formation." }, { "anchor": "On the statistics of proto-cluster candidates detected in the Planck\n all-sky survey: Observational investigations of the abundance of massive precursors of local\ngalaxy clusters (\"proto-clusters\") allow us to test the growth of density\nperturbations, to constrain cosmological parameters that control it, to test\nthe theory of non-linear collapse and how the galaxy formation takes place in\ndense environments. The Planck collaboration has recently published a catalogue\nof >~ 2000 cold extra-galactic sub-millimeter sources, i.e. with colours\nindicative of z >~ 2, almost all of which appear to be over-densities of\nstar-forming galaxies. They are thus considered as proto-cluster candidates.\nTheir number densities (or their flux densities) are far in excess of\nexpectations from the standard scenario for the evolution of large-scale\nstructure. Simulations based on a physically motivated galaxy evolution model\nshow that essentially all cold peaks brighter than S_{545GHz} = 500 mJy found\nin Planck maps after having removed the Galactic dust emission can be\ninterpreted as positive Poisson fluctuations of the number of high-z dusty\nproto-clusters within the same Planck beam, rather then being individual clumps\nof physically bound galaxies. This conclusion does not change if an empirical\nfit to the luminosity function of dusty galaxies is used instead of the\nphysical model. The simulations accurately reproduce the statistic of the\nPlanck detections and yield distributions of sizes and ellipticities in\nqualitative agreement with observations. The redshift distribution of the\nbrightest proto-clusters contributing to the cold peaks has a broad maximum at\n1.5 <~ z <~ 3. Therefore follow-up of Planck proto-cluster candidates will\nprovide key information on the high-z evolution of large scale structure.", "positive": "Rotating Accretion Flows: From Infinity to the Black Hole: Accretion onto a supermassive black hole of a rotating inflow is a\nparticularly difficult problem to study because of the wide range of length\nscales involved. There have been broadly utilized analytic and numerical\ntreatments of the global properties of accretion flows, but detailed numerical\nsimulations are required to address certain critical aspects. We use the ZEUS\ncode to run hydrodynamical simulations of rotating, axisymmetric accretion\nflows with Bremsstrahlung cooling, considering solutions for which the\ncentrifugal balance radius significantly exceeds the Schwarzschild radius, with\nand without viscous angular momentum transport. Infalling gas is followed from\nwell beyond the Bondi radius down to the vicinity of the black hole. We produce\na continuum of solutions with respect to the single parameter\nMdot_Bondi/Mdot_Edd, and there is a sharp transition between two general\nclasses of solutions at an Eddington ratio of Mdot_Bondi/Mdot_Edd ~ few x\n10^(-2). Our high inflow solutions are very similar to the standard Shakura &\nSunyaev (1973) results. But our low inflow results are to zeroth order the\nstationary Papaloizou and Pringle (1984) solution, which has no accretion. To\nnext order in the small, assumed viscosity they show circulation, with disk and\nconical wind outflows almost balancing inflow. These solutions are\ncharacterized by hot, vertically extended disks, and net accretion proceeds at\nan extremely low rate, only of order alpha times the inflow rate. Our\nsimulations have converged with respect to spatial resolution and temporal\nduration, and they do not depend strongly on our choice of boundary conditions." }, { "anchor": "On Synchronized Globular Cluster Formation over Supra-galactic Scales: A\n Virgo-Centaurus Group Connection: This work reports the detection of a multi peaked colour pattern in the\nintegrated colours distribution of globular clusters associated to the giant\nelliptical galaxy NGC 4486, using Next Generation Virgo Survey data. This\nfeature is imprinted on the well known bimodal colour distribution of these\nclusters. Remarkably, the pattern is similar to that found in previous works\nbased on photometry from the HST Advanced Camera Virgo Survey, in less massive\nVirgo galaxies. This characteristic can be traced up to to 45 arcmin (217 Kpc)\nin galactocentric radius. This suggests that globular cluster formation in\nVirgo has been regulated, at least partially, by a collective process composed\nby several discrete events, working on spatial scales comparable to the size of\nthe galaxy cluster. Furthermore, the presence of a similar colour pattern in\nNGC 5128, at the outskirsts of the Virgo Super-cluster, poses an intriguing\nquestion about the spatial scale of the phenomenon. The nature of the process\nthat leads to the colour pattern is unknown. However, energetic events\nconnected with galaxy or sub-galaxy cluster mergers and SMBH activity, in the\nearly Universe, appear as possible candidates to explain an eventual\nenhancement/quenching of the globular clusters formation, reflected in the\nmodulation of their integrated colours. Such events, presumably, may also have\nhad an impact on the whole star formation history in Virgo galaxies.", "positive": "The LAMOST Stellar Parameter Pipeline at Peking University --- LSP3: We introduce the LAMOST Stellar Parameter Pipeline at Peking University ---\nLSP3, developed and implemented for the determinations of radial velocity\n$V_{\\rm r}$ and stellar atmospheric parameters (effective temperature $T_{\\rm\neff}$, surface gravity log\\,$g$, metallicity [Fe/H]) for the LAMOST\nSpectroscopic Survey of the Galactic Anti-center (LSS-GAC). We describe the\nalgorithms of LSP3 and examine the accuracy of parameters yielded by it. The\nprecision and accuracy of parameters yielded are investigated by comparing\nresults of multi-epoch observations and of candidate members of open and\nglobular clusters, with photometric calibration, as well as with independent\ndeterminations available from a number of external databases, including the\nPASTEL archive, the APOGEE, SDSS and RAVE surveys, as well as those released in\nthe LAMOST DR1. The uncertainties of LSP3 parameters are characterized and\nquantified as a function of the spectral signal-to-noise ratio (SNR) and\nstellar atmospheric parameters. We conclude that the current implementation of\nLSP3 has achieved an accuracy of 5.0\\,km\\,s$^{-1}$, 150\\,K, 0.25\\,dex,\n0.15\\,dex for the radial velocity, effective temperature, surface gravity and\nmetallicity, respectively, for LSS-GAC spectra of FGK stars of SNRs per pixel\nhigher than 10. The LSP3 has been applied to over a million LSS-GAC spectra\ncollected hitherto. Stellar parameters yielded by the LSP3 will be released to\nthe general public following the data policy of LAMOST, together with estimates\nof the interstellar extinction $E(B-V)$ and stellar distances, deduced by\ncombining spectroscopic and multi-band photometric measurements using a variety\nof techniques." }, { "anchor": "Axial Ratio of Edge-On Spiral Galaxies as a Test For Extended Bright\n Radio Halos: We use surface brightness contour maps of nearby edge-on spiral galaxies to\ndetermine whether extended bright radio halos are common. In particular, we\ntest a recent model of the spatial structure of the diffuse radio continuum by\nSubrahmanyan and Cowsik which posits that a substantial fraction of the\nobserved high-latitude surface brightness originates from an extended Galactic\nhalo of uniform emissivity. Measurements of the axial ratio of emission\ncontours within a sample of normal spiral galaxies at 1500 MHz and below show\nno evidence for such a bright, extended radio halo. Either the Galaxy is\natypical compared to nearby quiescent spirals or the bulk of the observed\nhigh-latitude emission does not originate from this type of extended halo.", "positive": "The Spitzer c2d Survey of Nearby Dense Cores: VI. The Protostars of\n Lynds Dark Nebula 1221: Observations of Lynds Dark Nebula 1221 from the Spitzer Space Telescope are\npresented. These data show three candidate protostars towards L1221, only two\nof which were previously known. The infrared observations also show signatures\nof outflowing material, an interpretation which is also supported by radio\nobservations with the Very Large Array. In addition, molecular line maps from\nthe Five College Radio Astronomy Observatory are shown.\n One-dimensional dust continuum modelling of two of these protostars, IRS1 and\nIRS3, is described. These models show two distinctly different protostars\nforming in very similar environments. IRS1 shows a higher luminosity and larger\ninner radius of the envelope than IRS3. The disparity could be caused by a\ndifference in age or mass, orientation of outflow cavities, or the impact of a\nbinary in the IRS1 core." }, { "anchor": "Group quenching and galactic conformity at low redshift: We quantify the quenching impact of the group environment using the\nspectroscopic survey Galaxy and Mass Assembly (GAMA) to z=0.2. The fraction of\nred (quiescent) galaxies, whether in groups or isolated, increases with both\nstellar mass and large-scale (5 Mpc) density. At fixed stellar mass, the red\nfraction is on average higher for satellites of red centrals than of blue\n(star-forming) centrals, a galactic conformity effect that increases with\ndensity. Most of the signal originates from groups that have the highest\nstellar mass, reside in the densest environments, and have massive, red only\ncentrals. Assuming a color-dependent halo-to-stellar-mass ratio, whereby red\ncentral galaxies inhabit significantly more massive halos than blue ones of the\nsame stellar mass, two regimes emerge more distinctly: at log(Mhalo/Msol) < 13,\ncentral quenching is still ongoing, conformity is no longer existent, and\nsatellites and group centrals exhibit the same quenching excess over field\ngalaxies at all mass and density, in agreement with the concept of \"group\nquenching\"; at log(Mhalo/Msol) > 13, a cutoff that sets apart massive\n(log(M*/Msol) > 11), fully quenched group centrals, conformity is meaningless,\nand satellites undergo significantly more quenching than their counterparts in\nsmaller halos. The latter effect strongly increases with density, giving rise\nto the density-dependent conformity signal when both regimes are mixed. The\nstar-formation of blue satellites in massive halos is also suppressed compared\nto blue field galaxies, while blue group centrals and the majority of blue\nsatellites, which reside in low mass halos, show no deviation from the\ncolor-stellar mass relation of blue field galaxies.", "positive": "Modelling high-resolution ALMA observations of strongly lensed dustystar\n forming galaxies detected by Herschel: We present modelling of ~0.1arcsec resolution Atacama Large\nMillimetre/sub-millimeter Array imaging of seven strong gravitationally lensed\ngalaxies detected by the Herschel Space Observatory. Four of these systems are\ngalaxy-galaxy scale strong lenses, with the remaining three being group-scale\nlenses. Through careful modelling of visibilities, we infer the mass profiles\nof the lensing galaxies and by determining the magnification factors, we\ninvestigate the intrinsic properties and morphologies of the lensed\nsub-millimetre sources. We find that these sub-millimetre sources all have\nratios of star formation rate to dust mass that is consistent with or in excess\nof the mean ratio for high-redshift sub-millimetre galaxies and low redshift\nultra-luminous infrared galaxies. The contribution to the infrared luminosity\nfrom possible AGN is not quantified and so could be biasing our star formation\nrates to higher values. The majority of our lens models have mass density\nslopes close to isothermal, but some systems show significant differences." }, { "anchor": "Estimation of the Galactic Spiral Pattern Speed from Cepheids: To study the peculiarities of the Galactic spiral density wave, we have\nanalyzed the space velocities of Galactic Cepheids with proper motions from the\nHipparcos catalog and line-of-sight velocities from various sources. First,\nbased on the entire sample of 185 stars and taking $R_0 = 8$ kpc, we have found\nthe components of the peculiar solar velocity\n$(u_\\odot,v_\\odot,w_\\odot)=(7.6,11.6,6.1)\\pm(0.8,1.1,0.6)$ km s$^{-1}$, the\nangular velocity of Galactic rotation $\\Omega_0 = -27.4\\pm0.6$ km s$^{-1}$\nkpc$^{-1}$ and its derivatives $\\Omega^{'}_0 = +4.07\\pm0.21,$ km s$^{-1}$\nkpc$^{-2}$ and $\\Omega^{\"}_0 = -0.83\\pm0.17,$ km s$^{-1}$ kpc$^{-3}$, the\namplitudes of the velocity perturbations in the spiral density wave\n$f_R=-6.7\\pm0.7$ and $f_\\theta= 3.5\\pm0.5$ km s$^{-1}$, the pitch angle of a\ntwo-armed spiral pattern (m = 2) $i=-4.5\\pm0.1^\\circ$ (which corresponds to a\nwavelength $\\lambda=2.0\\pm0.1$ kpc), and the phase of the Sun in the spiral\ndensity wave $\\chi_\\odot=-191\\pm5^\\circ$. The phase $\\chi_\\odot$ has been found\nto change noticeably with the mean age of the sample. Having analyzed these\nphase shifts, we have determined the mean value of the angular velocity\ndifference $\\Omega_p-\\Omega$, which depends significantly on the calibrations\nused to estimate the individual ages of Cepheids. When estimating the ages of\nCepheids based on Efremov's calibration, we have found\n$|\\Omega_p-\\Omega_0|=9\\pm2$ km s$^{-1}$ kpc$^{-1}$. The ratio of the radial\ncomponent of the gravitational force produced by the spiral arms to the total\ngravitational force of the Galaxy has been estimated to be $f_{r0} = 0.04$.", "positive": "Formation of the SDC13 Hub-Filament System: A Cloud-Cloud Collision\n Imprinted on The Multiscale Magnetic Field: Hub-filament systems (HFSs) are potential sites of protocluster and massive\nstar formation, and play a key role in mass accumulation. We report JCMT POL-2\n850 $\\mu$m polarization observations toward the massive HFS SDC13. We detect an\norganized magnetic field near the hub center with a cloud-scale \"U-shape\"\nmorphology following the western edge of the hub. Together with larger-scale\nAPEX 13CO and PLANCK polarization data, we find that SDC13 is located at the\nconvergent point of three giant molecular clouds (GMCs) along a large-scale,\npartially spiral-like magnetic field. The smaller \"U-shape\" magnetic field is\nperpendicular to the large-scale magnetic field and the converging GMCs. We\nexplain this as the result of a cloud-cloud collision. Within SDC13, we find\nthat local gravity and velocity gradients point toward filament ridges and hub\ncenter. This suggests that gas can locally be pulled onto filaments and overall\nconverges to the hub center. A virial analysis of the central hub shows that\ngravity dominates magnetic and kinematic energy. Combining large- and\nsmall-scale analyses, we propose that SDC13 is initially formed from a\ncollision of clouds moving along the large-scale magnetic field. In the\npost-shock regions, after the initial turbulent energy has dissipated, gravity\ntakes over and starts to drive the gas accretion along the filaments toward the\nhub center." }, { "anchor": "A Search for H2O Megamasers in High-z Type-2 AGNs: We report a search for H2O megamasers in 274 SDSS type-2 AGNs (0.3 < z <\n0.83), half of which can be classified as type-2 QSOs from their [OIII] 5007\nluminosity, using the Robert C. Byrd Green Bank Telescope (GBT) and the\nEffelsberg 100-m radio telescope. Apart from the detection of the extremely\nluminous water vapor megamaser SDSS J080430.99+360718.1, already reported by\nBarvainis & Antonucci (2005), we do not find any additional line emission. This\nhigh rate of non-detections is compared to the water maser luminosity function\ncreated from the 78 water maser galaxies known to date and its extrapolation\ntowards the higher luminosities of \"gigamasers\" that we would have been able to\ndetect given the sensitivity of our survey. The properties of the known water\nmasers are summarized and discussed with respect to the nature of high-z type-2\nAGNs and megamasers in general. In the appendix, we list 173 additional objects\n(mainly radio galaxies, but also QSOs and galaxies) that were observed with the\nGBT, the Effelsberg 100-m radio telescope, or Arecibo Observatory without\nleading to the detection of water maser emission.", "positive": "Kinematics and Star Formation of High-Redshift Hot Dust-Obscured Quasars\n as Seen by ALMA: Hot, dust-obscured galaxies (Hot DOGs) are a population of hyper-luminous\nobscured quasars identified by WISE. We present ALMA observations of the [CII]\nfine-structure line and underlying dust continuum emission in a sample of seven\nof the most extremely luminous (EL; L$_{\\rm bol}$ $\\ge$ 10$^{14}$ L$_\\odot$)\nHot DOGs, at redshifts z ~ 3.0-4.6. The [CII] line is robustly detected in four\nobjects, tentatively in one, and likely red-shifted out of the spectral window\nin the remaining two based on additional data. On average, [CII] is red-shifted\nby ~ 780 km/s from rest-frame ultraviolet emission lines. EL Hot DOGs exhibit\nconsistently very high ionized gas surface densities, with $\\Sigma_{\\rm [CII]}$\n~ 1-2 x 10$^{9}$ L$_\\odot$ kpc$^{-2}$; as high as the most extreme cases seen\nin other high-redshift quasars. As a population, EL Hot DOG hosts seem to be\nroughly centered on the main-sequence of star forming galaxies, but the\nuncertainties are substantial and individual sources can fall above and below.\nThe average, intrinsic [CII] and dust continuum sizes (FWHMs) are ~ 2.1 kpc and\n~ 1.6 kpc, respectively, with a very narrow range of line-to-continuum size\nratios, 1.61 $\\pm$ 0.10, suggesting they could be linearly proportional. The\n[CII] velocity fields of EL Hot DOGs are diverse: from barely rotating\nstructures, to resolved hosts with ordered, circular motions, to complex,\ndisturbed systems that are likely the result of ongoing mergers. In contrast,\nall sources display large line-velocity dispersions, FWHM $\\gtrsim$ 500 km/s,\nwhich on average are larger than optically and IR-selected quasars at similar\nor higher redshifts. We argue that one possible hypothesis for the lack of a\ncommon velocity structure, the systematically large dispersion of the ionized\ngas, and the presence of nearby companion galaxies may be that, rather than a\nsingle event, the EL Hot DOG phase could be recurrent." }, { "anchor": "Impact of filaments on galaxy formation in their residing dark matter\n haloes: We make use of a high-resolution zoom-in hydrodynamical simulation to\ninvestigate the impact of filaments on galaxy formation in their residing dark\nmatter haloes. A method based on the density field and the Hoshen-Kopelman\nalgorithm is developed to identify filaments. We show that cold and dense gas\npreprocessed by dark matter filaments can be further accreted into residing\nindividual low-mass haloes in directions along the filaments. Consequently,\ncomparing with field haloes, gas accretion is very anisotropic for filament\nhaloes. About 30 percent of the accreted gas of a residing filament halo was\npreprocessed by filaments, leading to two different thermal histories for the\ngas in filament haloes. Filament haloes have higher baryon and stellar\nfractions when comparing with their field counterparts. Without including\nstellar feedback, our results suggest that filaments assist gas cooling and\nenhance star formation in their residing dark matter haloes at high redshifts\n(i.e. z=4.0 and 2.5).", "positive": "Dual Active Galactic Nuclei in Nearby Galaxies: Galaxy mergers play a crucial role in the formation of massive galaxies and\nthe buildup of their bulges. An important aspect of the merging process is the\nin-spiral of the supermassive black-holes (SMBHs) to the centre of the merger\nremnant and the eventual formation of a SMBH binary. If both the SMBHs are\naccreting they will form a dual or binary active galactic nucleus (DAGN). The\nfinal merger remnant is usually very bright and shows enhanced star formation.\nIn this paper we summarize the current sample of DAGN from previous studies and\ndescribe methods that can be used to identify strong DAGN candidates from\noptical and spectroscopic surveys. These methods depend on the Doppler\nseparation of the double peaked AGN emission lines, the nuclear velocity\ndispersion of the galaxies and their optical/UV colours. We describe two high\nresolution, radio observations of DAGN candidates that have been selected based\non their double peaked optical emission lines (DPAGN). We also examine whether\nDAGN host galaxies have higher star formation rates (SFRs) compared to merging\ngalaxies that do not appear to have DAGN. We find that the SFR is not higher\nfor DAGN host galaxies. This suggests that the SFRs in DAGN host galaxies is\ndue to the merging process itself and not related to the presence of two AGN in\nthe system." }, { "anchor": "The Dragonfly Nearby Galaxies Survey. III. The Luminosity Function of\n the M101 Group: We obtained follow-up HST observations of the seven low surface brightness\ngalaxies discovered with the Dragonfly Telephoto Array in the field of the\nmassive spiral galaxy M101. Out of the seven galaxies, only three were resolved\ninto stars and are potentially associated with the M101 group at $D=7\\text{\nMpc}$. Based on HST ACS photometry in the broad F606W and F814W filters, we use\na maximum likelihood algorithm to locate the Tip of the Red Giant Branch (TRGB)\nin galaxy color-magnitude diagrams. Distances are $6.38^{+0.35}_{-0.35},\n6.87^{+0.21}_{-0.30}$ and $6.52^{+0.25}_{-0.27} \\text{ Mpc}$ and we confirm\nthat they are members of the M101 group. Combining the three confirmed low\nluminosity satellites with previous results for brighter group members, we find\nthe M101 galaxy group to be a sparsely populated galaxy group consisting of\nseven group members, down to $M_V = -9.2 \\text{ mag}$. We compare the M101\ncumulative luminosity function to that of the Milky Way and M31. We find that\nthey are remarkably similar; In fact, the cumulative luminosity function of the\nM101 group gets even flatter for fainter magnitudes, and we show that the M101\ngroup might exhibit the two known small-scale flaws in the\n$\\Lambda\\textrm{CDM}$ model, namely `the missing satellite' problem and the\n`too big to fail' problem. Kinematic measurements of M101$'$s satellite\ngalaxies are required to determine whether the `too big to fail' problem does\nin fact exist in the M101 group.", "positive": "The AGORA High-Resolution Galaxy Simulations Comparison Project. II:\n Isolated Disk Test: Using an isolated Milky Way-mass galaxy simulation, we compare results from 9\nstate-of-the-art gravito-hydrodynamics codes widely used in the numerical\ncommunity. We utilize the infrastructure we have built for the AGORA\nHigh-resolution Galaxy Simulations Comparison Project. This includes the common\ndisk initial conditions, common physics models (e.g., radiative cooling and UV\nbackground by the standardized package Grackle) and common analysis toolkit yt,\nall of which are publicly available. Subgrid physics models such as Jeans\npressure floor, star formation, supernova feedback energy, and metal production\nare carefully constrained across code platforms. With numerical accuracy that\nresolves the disk scale height, we find that the codes overall agree well with\none another in many dimensions including: gas and stellar surface densities,\nrotation curves, velocity dispersions, density and temperature distribution\nfunctions, disk vertical heights, stellar clumps, star formation rates, and\nKennicutt-Schmidt relations. Quantities such as velocity dispersions are very\nrobust (agreement within a few tens of percent at all radii) while measures\nlike newly-formed stellar clump mass functions show more significant variation\n(difference by up to a factor of ~3). Systematic differences exist, for\nexample, between mesh-based and particle-based codes in the low density region,\nand between more diffusive and less diffusive schemes in the high density tail\nof the density distribution. Yet intrinsic code differences are generally small\ncompared to the variations in numerical implementations of the common subgrid\nphysics such as supernova feedback. Our experiment reassures that, if\nadequately designed in accordance with our proposed common parameters, results\nof a modern high-resolution galaxy formation simulation are more sensitive to\ninput physics than to intrinsic differences in numerical schemes." }, { "anchor": "Unification of Luminous Type 1 Quasars through CIV Emission: Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of\nproperties exhibited by high-ionization, broad emission lines, such as CIV\n1549. Specifically we investigate the anti-correlation between L_UV and\nemission line EQW (the Baldwin Effect) and the \"blueshifting\" of\nhigh-ionization emission lines. The blueshift of the CIV emission line is\nnearly ubiquitous, with a mean shift of 810 km/s for radio-quiet (RQ) quasars\nand 360 km/s for radio-loud (RL) quasars, and the Baldwin Effect is present in\nboth RQ and RL samples. Composite spectra are constructed as a function of CIV\nemission line properties in attempt to reveal empirical relationships between\ndifferent line species and the SED. Within a two-component disk+wind model of\nthe broad emission line region (BELR), where the wind filters the continuum\nseen by the disk component, we find that RL quasars are consistent with being\ndominated by the disk component, while BALQSOs are consistent with being\ndominated by the wind component. Some RQ objects have emission line features\nsimilar to RL quasars; they may simply have insufficient black hole (BH) spin\nto form radio jets. Our results suggest that there could be significant\nsystematic errors in the determination of L_bol and BH mass that make it\ndifficult to place these findings in a more physical context. However, it is\npossible to classify quasars in a paradigm where the diversity of BELR\nparameters are due to differences in an accretion disk wind between quasars\n(and over time); these differences are underlain primarily by the SED, which\nultimately must be tied to BH mass and accretion rate.", "positive": "The dynamic stage of clusters and its influence on the stellar\n populations of galaxies: We investigate the stellar populations of galaxies in clusters at different\ndynamical stages, aiming to identify possible effects of the relaxation state\nof the cluster or subcluster on the star formation histories of its galaxies.\nWe have developed and applied a code for kinematic substructure detection to a\nsample of 412 galaxy clusters drawn from the \\citet[]{tempel2012} catalogue,\nfinding a frequency of substructures of 45\\%. We have extracted mean stellar\nages with the {\\sc{starlight}} spectral synthesis code applied to SDSS-III\nspectra of the sample galaxies. We found lower mean stellar ages in unrelaxed\nclusters relative to relaxed clusters. For unrelaxed clusters, we separated\nprimary and secondary subhalos and found that, while relaxed clusters and\nprimaries present similar masses and age distributions, secondaries present\nyounger stellar populations, mainly due to low-mass galaxies ($\\log\nM_\\star/M_\\odot \\lesssim 11$\\,dex). An age-clustercentric radius relation is\nseen for all subhalos irrespective of the presence of substructures. We also\nobserve relations between the mean stellar age and mass of relaxed and\nunrelaxed clusters, massive systems presenting higher mean ages. The locus of\nthese relations is distinct between relaxed and unrelaxed clusters, but become\nindistinguishable when separating primaries and secondaries. Our results\nsuggest that differences between relaxed and unrelaxed clusters are mainly\ndriven by low-mass systems in the clusters outskirts, and that, while\npre-processing can be seen in the subcomponents of dynamically young clusters,\nsome evolution in the stellar populations must occur during the clusters\nrelaxation." }, { "anchor": "The white dwarf population of NGC 6397: NGC 6397 is one of the most interesting, well observed and theoretically\nstudied globular clusters. The existing wealth of observations allows us to\nstudy the reliability of the theoretical white dwarf cooling sequences of low\nmetallicity progenitors,to determine its age and the percentage of unresolved\nbinaries, and to assess other important characteristics of the cluster, like\nthe slope of the initial mass function, or the fraction of white dwarfs with\nhydrogen deficient atmospheres. We present a population synthesis study of the\nwhite dwarf population of NGC 6397. In particular, we study the shape of the\ncolor-magnitude diagram, and the corresponding magnitude and color\ndistributions. We do this using an up-to-date Monte Carlo code that\nincorporates the most recent and reliable cooling sequences and an accurate\nmodeling of the observational biases. We find a good agreement between our\ntheoretical models and the observed data. In particular, we find that this\nagreement is best for those cooling sequences that take into account residual\nhydrogen burning. This result has important consequences for the evolution of\nprogenitor stars during the thermally-pulsing asymptotic giant branch phase,\nsince it implies that appreciable third dredge-up in low-mass, low-metallicity\nprogenitors is not expected to occur. Using a standard burst duration of 1.0\nGyr, we obtain that the age of the cluster is 12.8+0.50-0.75 Gyr. Larger ages\nare also compatible with the observed data, but then realistic longer durations\nof the initial burst of star formation are needed to fit the luminosity\nfunction. We conclude that a correct modeling of the white dwarf opulation of\nglobular clusters, used in combination with the number counts of main sequence\nstars provides an unique tool to model the properties of globular clusters.", "positive": "FIRE in the Field: Simulating the Threshold of Galaxy Formation: We present a suite of 15 cosmological zoom-in simulations of isolated dark\nmatter halos, all with masses of $M_{\\rm halo} \\approx 10^{10}\\,{\\rm M}_\\odot$\nat $z=0$, in order to understand the relationship between halo assembly, galaxy\nformation, and feedback's effects on the central density structure in dwarf\ngalaxies. These simulations are part of the Feedback in Realistic Environments\n(FIRE) project and are performed at extremely high resolution. The resultant\ngalaxies have stellar masses that are consistent with rough abundance matching\nestimates, coinciding with the faintest galaxies that can be seen beyond the\nvirial radius of the Milky Way ($M_\\star/{\\rm M}_\\odot\\approx 10^5-10^7$). This\nnon-negligible spread in stellar mass at $z=0$ in halos within a narrow range\nof virial masses is strongly correlated with central halo density or maximum\ncircular velocity $V_{\\rm max}$. Much of this dependence of $M_\\star$ on a\nsecond parameter (beyond $M_{\\rm halo}$) is a direct consequence of the $M_{\\rm\nhalo}\\sim10^{10}\\,{\\rm M}_\\odot$ mass scale coinciding with the threshold for\nstrong reionization suppression: the densest, earliest-forming halos remain\nabove the UV-suppression scale throughout their histories while late-forming\nsystems fall below the UV-suppression scale over longer periods and form fewer\nstars as a result. In fact, the latest-forming, lowest-concentration halo in\nour suite fails to form any stars. Halos that form galaxies with\n$M_\\star\\gtrsim2\\times10^{6}\\,{\\rm M}_\\odot$ have reduced central densities\nrelative to dark-matter-only simulations, and the radial extent of the density\nmodifications is well-approximated by the galaxy half-mass radius $r_{1/2}$.\nThis apparent stellar mass threshold of $M_\\star \\approx 2\\times 10^{6} \\approx\n2\\times 10^{-4} \\,M_{\\rm halo}$ is broadly consistent with previous work and\nprovides a testable prediction of FIRE feedback models in LCDM." }, { "anchor": "SIBELIUS-DARK: a galaxy catalogue of the Local Volume from a constrained\n realisation simulation: We present SIBELIUS-DARK, a constrained realisation simulation of the local\nvolume to a distance of 200~Mpc from the Milky Way. SIBELIUS-DARK is the first\nstudy of the \\textit{Simulations Beyond The Local Universe} (SIBELIUS) project,\nwhich has the goal of embedding a model Local Group-like system within the\ncorrect cosmic environment. The simulation is dark-matter-only, with the galaxy\npopulation calculated using the semi-analytic model of galaxy formation,\nGALFORM. We demonstrate that the large-scale structure that emerges from the\nSIBELIUS constrained initial conditions matches well the observational data.\nThe inferred galaxy population of SIBELIUS-DARK also match well the\nobservational data, both statistically for the whole volume and on an\nobject-by-object basis for the most massive clusters. For example, the $K$-band\nnumber counts across the whole sky, and when divided between the northern and\nsouthern Galactic hemispheres, are well reproduced by SIBELIUS-DARK. We find\nthat the local volume is somewhat unusual in the wider context of $\\Lambda$CDM:\nit contains an abnormally high number of supermassive clusters, as well as an\noverall large-scale underdensity at the level of $\\approx 5$\\% relative to the\ncosmic mean. However, whilst rare, the extent of these peculiarities does not\nsignificantly challenge the $\\Lambda$CDM model. SIBELIUS-DARK is the most\ncomprehensive constrained realisation simulation of the local volume to date,\nand with this paper we publicly release the halo and galaxy catalogues at\n$z=0$, which we hope will be useful to the wider astronomy community.", "positive": "Connecting the Scales: Large Area High-resolution Ammonia Mapping of NGC\n 1333: We use NH3 inversion transitions to trace the dense gas in the NGC 1333\nregion of the Perseus molecular cloud. NH3(1,1) and NH3(2,2) maps covering an\narea of 102 square arcminutes at an angular resolution of ~3.7\" are produced by\ncombining VLA interferometric observations with GBT single dish maps. The\ncombined maps have a spectral resolution of 0.14 km/s and a sensitivity of 4\nmJy/beam. We produce integrated intensity maps, peak intensity maps and\ndispersion maps of NH3(1,1) and NH3(2,2) and a line-of-sight velocity map of\nNH3(1,1). These are used to derive the optical depth for the NH3(1,1) main\ncomponent, the excitation temperature of NH3(1,1), and the rotational\ntemperature, kinetic temperature and column density of NH3 over the mapped\narea.\n We compare these observations with the CARMA J=1-0 observations of N2H+ and\nH13CO+ and conclude that they all trace the same material in these dense star\nforming regions. From the NH3(1,1) velocity map, we find that a velocity\ngradient ridge extends in an arc across the entire southern part of NGC 1333.\nWe propose that a large scale turbulent cell is colliding with the cloud, which\ncould result in the formation of a layer of compressed gas. This region along\nthe velocity gradient ridge is dotted with Class 0/I YSOs, that could have\nformed from local overdensities in the compressed gas leading to gravitational\ninstabilities. The NH3(1,1) velocity dispersion map also has relatively high\nvalues along this region, thereby substantiating the shock layer argument." }, { "anchor": "The EAGLE simulations: atomic hydrogen associated with galaxies: We examine the properties of atomic hydrogen (HI) associated with galaxies in\nthe EAGLE simulations of galaxy formation. EAGLE's feedback parameters were\ncalibrated to reproduce the stellar mass function and galaxy sizes at $z=0.1$,\nand we assess whether this calibration also yields realistic HI properties. We\nestimate the self-shielding density with a fitting function calibrated using\nradiation transport simulations, and correct for molecular hydrogen with\nempirical or theoretical relations. The `standard-resolution' simulations\nsystematically underestimate HI column densities, leading to an HI deficiency\nin low-mass ($M_\\star < 10^{10}M_\\odot$) galaxies and poor reproduction of the\nobserved HI mass function. These shortcomings are largely absent from EAGLE\nsimulations featuring a factor of 8 (2) better mass (spatial) resolution,\nwithin which the HI mass of galaxies evolves more mildly from $z=1$ to $0$ than\nin the standard-resolution simulations. The largest-volume simulation\nreproduces the observed clustering of HI systems, and its dependence on\nHI-richness. At fixed $M_\\star$, galaxies acquire more HI in simulations with\nstronger feedback, as they become associated with more massive haloes and\nhigher infall rates. They acquire less HI in simulations with a greater star\nformation efficiency, since the star formation and feedback necessary to\nbalance the infall rate is produced by smaller gas reservoirs. The simulations\nindicate that the HI of present-day galaxies was acquired primarily by the\nsmooth accretion of ionized, intergalactic gas at $z\\simeq1$, which later\nself-shields, and that only a small fraction is contributed by the\nreincorporation of gas previously heated strongly by feedback. HI reservoirs\nare highly dynamic: over $40$ percent of HI associated with $z=0.1$ galaxies is\nconverted to stars or ejected by $z=0$.", "positive": "GOODS-HERSCHEL: star formation, dust attenuation and the FIR-radio\n correlation on the Main Sequence of star-forming galaxies up to z~4: We use deep panchromatic datasets in the GOODS-N field, from GALEX to the\ndeepest Herschel far-infrared and VLA radio continuum imaging, to explore,\nusing mass-complete samples, the evolution of the star formation activity and\ndust attenuation of star-forming galaxies to z~4. Our main results can be\nsummarized as follows: i) the slope of the SFR-M correlation is consistent with\nbeing constant, and equal to ~0.8 at least up to z~1.5, while its normalization\nkeeps increasing with redshift; ii) for the first time here we are able to\nexplore the FIR-radio correlation for a mass-selected sample of star-forming\ngalaxies: the correlation does not evolve up to z~4; iii) we confirm that\ngalaxy stellar mass is a robust proxy for UV dust attenuation in star-forming\ngalaxies, with more massive galaxies being more dust attenuated, strikingly we\nfind that this attenuation relation evolves very weakly with redshift, the\namount of dust attenuation increasing by less than 0.3 magnitudes over the\nredshift range [0.5-4] for a fixed stellar mass, as opposed to a tenfold\nincrease of star formation rate; iv) the correlation between dust attenuation\nand the UV spectral slope evolves in redshift, with the median UV spectral\nslope of star-forming galaxies becoming bluer with redshift. By z~3, typical UV\nslopes are inconsistent, given the measured dust attenuation, with the\npredictions of commonly used empirical laws. Finally, building on existing\nresults, we show that gas reddening is marginally larger (by a factor of around\n1.3) than stellar reddening at all redshifts probed, and also that the amount\nof dust attenuation at a fixed ISM metallicity increases with redshift. We\nspeculate that our results support evolving ISM conditions of typical\nstar-forming galaxies such that at z~1.5 Main Sequence galaxies have ISM\nconditions getting closer to those of local starbursts." }, { "anchor": "Suppressing star formation in quiescent galaxies with supermassive black\n hole winds: Quiescent galaxies with little or no ongoing star formation dominate the\ngalaxy population above $M_{*}\\sim 2 \\times 10^{10}~M_{\\odot}$, where their\nnumbers have increased by a factor of $\\sim25$ since $z\\sim2$. Once star\nformation is initially shut down, perhaps during the quasar phase of rapid\naccretion onto a supermassive black hole, an unknown mechanism must remove or\nheat subsequently accreted gas from stellar mass loss or mergers that would\notherwise cool to form stars. Energy output from a black hole accreting at a\nlow rate has been proposed, but observational evidence for this in the form of\nexpanding hot gas shells is indirect and limited to radio galaxies at the\ncenters of clusters, which are too rare to explain the vast majority of the\nquiescent population. Here we report bisymmetric emission features co-aligned\nwith strong ionized gas velocity gradients from which we infer the presence of\ncentrally-driven winds in typical quiescent galaxies that host low-luminosity\nactive nuclei. These galaxies are surprisingly common, accounting for as much\nas $10\\%$ of the population at $M_* \\sim 2 \\times 10^{10}~ M_{\\odot}$. In a\nprototypical example, we calculate that the energy input from the galaxy's\nlow-level active nucleus is capable of driving the observed wind, which\ncontains sufficient mechanical energy to heat ambient, cooler gas (also\ndetected) and thereby suppress star formation.", "positive": "Constraining Millimeter Dust Emission in Nearby Galaxies with NIKA2: the\n case of NGC2146 and NGC2976: This study presents the first millimeter continuum mapping observations of\ntwo nearby galaxies, the starburst spiral galaxy NGC2146 and the dwarf galaxy\nNGC2976, at 1.15 mm and 2 mm using the NIKA2 camera on the IRAM 30m telescope,\nas part of the Guaranteed Time Large Project IMEGIN. These observations provide\nrobust resolved information about the physical properties of dust in nearby\ngalaxies by constraining their FIR-radio SED in the millimeter domain. After\nsubtracting the contribution from the CO line emission, the SEDs are modeled\nspatially using a Bayesian approach. Maps of dust mass surface density,\ntemperature, emissivity index, and thermal radio component of the galaxies are\npresented, allowing for a study of the relations between the dust properties\nand star formation activity (using observations at 24$\\mu$m as a tracer). We\nreport that dust temperature is correlated with star formation rate in both\ngalaxies. The effect of star formation activity on dust temperature is stronger\nin NGC2976, an indication of the thinner interstellar medium of dwarf galaxies.\nMoreover, an anti-correlation trend is reported between the dust emissivity\nindex and temperature in both galaxies." }, { "anchor": "A Simple and Accurate Network for Hydrogen and Carbon Chemistry in the\n ISM: Chemistry plays an important role in the interstellar medium (ISM),\nregulating heating and cooling of the gas, and determining abundances of\nmolecular species that trace gas properties in observations. Although solving\nthe time-dependent equations is necessary for accurate abundances and\ntemperature in the dynamic ISM, a full chemical network is too computationally\nexpensive to incorporate in numerical simulations. In this paper, we propose a\nnew simplified chemical network for hydrogen and carbon chemistry in the atomic\nand molecular ISM. We compare results from our chemical network in detail with\nresults from a full photo-dissociation region (PDR) code, and also with the\nNelson & Langer (1999) (NL99) network previously adopted in the simulation\nliterature. We show that our chemical network gives similar results to the PDR\ncode in the equilibrium abundances of all species over a wide range of\ndensities, temperature, and metallicities, whereas the NL99 network shows\nsignificant disagreement. Applying our network in 1D models, we find that the\n$\\mathrm{CO}$-dominated regime delimits the coldest gas and that the\ncorresponding temperature tracks the cosmic ray ionization rate in molecular\nclouds. We provide a simple fit for the locus of $\\mathrm{CO}$ dominated\nregions as a function of gas density and column. We also compare with\nobservations of diffuse and translucent clouds. We find that the $\\mathrm{CO}$,\n$\\mathrm{CHx}$ and $\\mathrm{OHx}$ abundances are consistent with equilibrium\npredictions for densities $n=100-1000~\\mathrm{cm^{-3}}$, but the predicted\nequilibrium $\\mathrm{C}$ abundance is higher than observations, signaling the\npotential importance of non-equilibrium/dynamical effects.", "positive": "The influence of black holes on the binary population of the globular\n cluster Palomar 5: The discovery of stellar-mass black holes (BHs) in globular clusters (GCs)\nraises the possibility of long-term retention of BHs within GCs. These BHs\ninfluence various astrophysical processes, including merger-driven\ngravitational waves and the formation of X-ray binaries. They also impact\ncluster dynamics by heating and creating low-density cores. Previous N-body\nmodels suggested that Palomar 5, a low-density GC with long tidal tails, may\ncontain more than 100 BHs. To test this scenario, we conduct N-body simulations\nof Palomar 5 with primordial binaries to explore the influence of BHs on binary\npopulations and the stellar mass function. Our results show that primordial\nbinaries have minimal effect on the long-term evolution. In dense clusters with\nBHs, the fraction of wide binaries with periods >$10^5$ days decreases, and the\ndisruption rate is independent of the initial period distribution. Multi-epoch\nspectroscopic observations of line-of-sight velocity changes can detect most\nbright binaries with periods below $10^4$ days, significantly improving\nvelocity dispersion measurements. Four BH-MS binaries in the model with BHs\nsuggests their possible detection through the same observation method.\nIncluding primordial binaries leads to a flatter inferred mass function because\nof spatially unresolved binaries, leading to a better match of the observations\nthan models without binaries, particularly in Palomar 5's inner region. Future\nobservations should focus on the cluster velocity dispersion and binaries with\nperiods of $10^4-10^5$ days in Palomar 5's inner and tail regions to constrain\nBH existence." }, { "anchor": "Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA): The\n core of the highest redshift galaxy overdensity at $z = 7.88$ confirmed by\n NIRSpec/JWST: The protoclusters in the epoch of reionization, traced by galaxies\noverdensity regions, are ideal laboratories for studying the process of stellar\nassembly and cosmic reionization. We present the spectroscopic confirmation of\nthe core of the most distant protocluster at $z = 7.88$, A2744-z7p9OD, with the\nJames Webb Space Telescope NIRSpec integral field unit spectroscopy. The core\nregion includes as many as 4 galaxies detected in [OIII] 4960 \\AA\\ and 5008\n\\AA\\ in a small area of $\\sim 3\\arcsec \\times 3\\arcsec$, corresponding to\n$\\sim$ 11 kpc $\\times$ 11 kpc, after the lensing magnification correction.\nThree member galaxies are also tentatively detected in dust continuum in\nAtacama Large Millimeter/submillimeter Array Band 6, which is consistent with\ntheir red ultraviolet continuum slopes, $\\beta \\sim -1.3$. The member galaxies\nhave stellar masses in the range of log($M_{*}/M_{\\rm \\odot}$) $\\sim 7.6-9.2$\nand star formation rates of $\\sim 3-50$ $M_{\\rm \\odot}$ yr$^{-1}$, showing a\ndiversity in their properties. FirstLight cosmological simulations reproduce\nthe physical properties of the member galaxies including the stellar mass,\n[OIII] luminosity, and dust-to-stellar mass ratio, and predict that the member\ngalaxies are on the verge of merging in a few to several tens Myr to become a\nlarge galaxy with $M_{\\rm *}\\sim 6\\times10^{9} M_{\\rm \\odot}$. The presence of\na multiple merger and evolved galaxies in the core region of A2744-z7p9OD\nindicates that environmental effects are already at work 650 Myr after the Big\nBang.", "positive": "VLA detects CO(1-0) emission in the z=3.65 quasar SDSS J160705+533558: We present CO(1--0) observations of the high-redshift quasar SDSS\nJ160705+533558 ($z=3.653$) using the Karl G. Jansky Very Large Array (VLA). We\ndetect CO emission associated with the quasar and at $\\sim16.8\\,\\rm kpc$\nprojected distance from it, separated by $\\sim800\\,\\rm km\\,s^{-1}$ in velocity.\nThe total molecular gas mass of this system is $\\sim5\\times10^{10}\\,\\rm\nM_{\\odot}$. By comparing our CO detections with previous submillimetre (submm)\nobservations of the source, an offset between the different emission components\nis revealed: the peak of the submm emission is offset from the quasar and from\nthe CO companion detected in our VLA data. To explain our findings, we propose\na scenario similar to that for the Antennae galaxies: SDSS J160705+533558 might\nbe a merger system in which the quasar and the CO companion are the merging\ngalaxies, whose interaction resulted in the formation of a dusty, star-forming\noverlap region between the galaxies that is dominant at the submm wavelengths." }, { "anchor": "Structural diversity of disc galaxies originating in the cold gas inflow\n from cosmic webs: Disc galaxies show a large morphological diversity with varying contribution\nof three major structural components; thin discs, thick discs, and central\nbulges. Dominance of bulges increases with the galaxy mass (Hubble sequence)\nwhereas thick discs are more prominent in lower mass galaxies. Because galaxies\ngrow with the accretion of matter, this observed variety should reflect\ndiversity in accretion history. On the basis of the prediction by the cold-flow\ntheory for galactic gas accretion and inspired by the results of previous\nstudies, we put a hypothesis that associates different accretion modes with\ndifferent components. Namely, thin discs form as the shock-heated hot gas in\nhigh-mass halos gradually accretes to the central part, thick discs grow by the\ndirect accretion of cold gas from cosmic webs when the halo mass is low, and\nfinally bulges form by the inflow of cold gas through the shock-heated gas in\nhigh-redshift massive halos. We show that this simple hypothesis reproduces the\nmean observed variation of galaxy morphology with the galaxy mass. This\nscenario also predicts that thick discs are older and poorer in metals than\nthin discs, in agreement with the currently available observational data.", "positive": "A Large Sample of Extremely Metal-poor Galaxies at $z<1$ Identified from\n the DESI Early Data: Extremely metal-poor galaxies (XMPGs) at relatively low redshift are\nexcellent laboratories for studying galaxy formation and evolution in the early\nuniverse. Much effort has been spent on identifying them from large-scale\nspectroscopic surveys or spectroscopic follow-up observations. Previous work\nhas identified a few hundred XMPGs. In this work, we obtain a large sample of\n223 XMPGs at $z<1$ from the early data of the Dark Energy Spectroscopic\nInstrument (DESI). The oxygen abundance is determined using the direct $T_{\\rm\ne}$ method based on the detection of the [O III]$\\lambda$4363 line. The sample\nincludes 95 confirmed XMPGs based on the oxygen abundance uncertainty;\nremaining 128 galaxies are regarded as XMPG candidates. These XMPGs are only\n0.01% of the total DESI observed galaxies. Their coordinates and other\nproprieties are provided in the paper. The most XMPG has an oxygen abundance of\n$\\sim 1/34 Z_{\\odot}$, stellar mass of about $1.5\\times10^7 M_{\\odot}$ and star\nformation rate of 0.22 $M_{\\odot}$ yr$^{-1}$. The two most XMPGs present\ndistinct morphologies suggesting different formation mechanisms. The local\nenvironmental investigation shows that XMPGs preferentially reside in\nrelatively low-density regions. Many of them fall below the stellar\nmass-metallicity relations (MZRs) of normal star-forming galaxies. From a\ncomparison of the MZR with theoretical simulations, it appears that XMPGs are\ngood analogs to high-redshift star-forming galaxies. The nature of these XMPG\npopulations will be further investigated in detail with larger and more\ncomplete samples from the on-going DESI survey." }, { "anchor": "A New Recipe for Obtaining Central Volume Densities of Prestellar Cores\n from Size Measurements: We propose a simple analytical method for estimating the central volume\ndensity of prestellar molecular cloud cores from their column density profiles.\nPrestellar cores feature a flat central part of the column density and volume\ndensity profiles of the same size indicating the existence of a uniform density\ninner region. The size of this region is set by the thermal pressure force\nwhich depends only on the central volume density and temperature of the core,\nand can provide a direct measurement of the central volume density. Thus a\nsimple length measurement can immediately yield a central density estimate\nindependent of any dynamical model for the core and without the need for\nfitting. Using the radius at which the column density is 90% of the central\nvalue as an estimate of the size of the flat inner part of the column density\nprofile yields an estimate of the central volume density within a factor of 2\nfor well resolved cores.", "positive": "On the pumping of the CS($v=0$) masers in W51 e2e: We present the results of numerically solving the rate equations for the\nfirst 31 rotational states of CS in the ground vibrational state to determine\nthe conditions under which the J=1-0, J=2-1 and J=3-2 transitions are inverted\nto produce maser emission. The essence of our results is that the CS($v=0$)\nmasers are collisionally pumped and that, depending on the spectral energy\ndistribution, dust emission can suppress the masers. Apart from the J=1-0 and\nJ=2-1 masers the calculations also show that the J=3-2 transition can be\ninverted to produce maser emission. It is found that beaming is necessary to\nexplain the observed brightness temperatures of the recently discovered CS\nmasers in W51 e2e. The model calculations suggest that a CS abundance of a few\ntimes $10^{-5}$ and CS($v=0$) column densities of the order\n$10^{16}\\,\\mathrm{cm^{-2}}$ are required for these masers. The rarity of the CS\nmasers in high mass star forming regions might be the result of a required high\nCS abundance as well as due to attenuation of the maser emission inside as well\nas outside of the hot core." }, { "anchor": "Confirmation and refutation of very luminous galaxies in the early\n universe: During the first 500 million years of cosmic history, the first stars and\ngalaxies formed, seeding the Universe with heavy elements and eventually\nreionizing the intergalactic medium. Observations with JWST have uncovered a\nsurprisingly high abundance of candidates for early star-forming galaxies, with\ndistances (redshifts, $z$), estimated from multi-band photometry, as large as\n$z\\approx 16$, far beyond pre-JWST limits. While generally robust, such\nphotometric redshifts can suffer from degeneracies and occasionally\ncatastrophic errors. Spectroscopic measurement is required to validate these\nsources and to reliably quantify physical properties that can constrain galaxy\nformation models and cosmology. Here we present JWST spectroscopy that confirms\nredshifts for two very luminous galaxies with $z > 11$, but also demonstrates\nthat another candidate with suggested $z\\approx 16$ instead has $z = 4.9$, with\nan unusual combination of nebular line emission and dust reddening that mimics\nthe colors expected for much more distant objects. These results reinforce\nevidence for the early, rapid formation of remarkably luminous galaxies, while\nalso highlighting the necessity of spectroscopic verification. The large\nabundance of bright, early galaxies may indicate shortcomings in current galaxy\nformation models, or deviation from physical properties (such as the stellar\ninitial mass function) that are generally believed to hold at later times.", "positive": "Phase Space Models of the Dwarf Spheroidal Galaxies: This paper introduces new phase-space models of dwarf spheroidal galaxies\n(dSphs). The stellar component has an isotropic, lowered isothermal (or King)\ndistribution function. A physical basis for the isotropization of stellar\nvelocities is given by tidal stirring, whilst the isothermality of the\ndistribution function guarantees the observed flatness of the velocity\ndispersion profile in the inner parts. Our models reproduce the data on the\nhalf-light radius and line of sight central velocity dispersion of the dSphs.\nWe show that different dark halo profiles -- whether cored or cusped -- lead to\nvery similar mass estimates within one particular radius, namely 1.7 half-light\nradii. Deviations between mass measures due to different density profiles are\nsubstantially smaller than the uncertainties propagated by the observational\nerrors. We produce a mass measure for each of the Milky Way dSphs and find that\nthe two most massive are the most luminous, namely Sagittarius (~ 2.8 x 10^8\nsolar masses) and Fornax (~ 1.3 x 10^8 solar masses). The least massive of the\nMilky Way satellites are Willman 1 (~ 4 x 10^5 solar masses) and Segue 1 (~ 6 x\n10^5 solar masses)." }, { "anchor": "The dust-star interplay in late-type galaxies at z < 0.5: forecasts for\n the JWST: In recent years, significant growth in the amount of data available to\nastronomers has opened up the possibility to uncover fundamental correlations,\nlinking the dust component of a galaxy to its star formation rate (SFR). In\nthis paper, we re-examine these correlations, investigating the origin of the\nobserved scatter, and the ability of the James Webb Space Telescope (JWST) to\nexplore such relations in the early Universe. We defined a sample of about 800\nnormal star-forming galaxies with photometries in the range of 0.15 < $\\lambda$\n< 500 microns and analysed them with different spectral energy distribution\n(SED) fitting methods. With the SEDs extracted, we investigated the detection\nrate at different redshifts with the MId-Infrared instruments (MIRI) onboard\nthe JWST. Dust luminosity (L$_d$) and SFR show a strong correlation, but for\nSFR < 2 M$_\\odot$ yr$^{-1}$, the correlation scatter increases dramatically. We\nshow that selection based on the fraction of ultraviolet (UV) emission absorbed\nby dust, that is, the UV extinction, greatly reduces the data dispersion.\nReproducing the sensitivity of the Cosmic Evolution Early Release Science\nSurvey (CEERS) and classifying galaxies according to their SFR and stellar mass\n(M$_\\ast$), we investigated the MIRI detection rate as a function of the\nphysical properties of the galaxies. Fifty percent of the objects with SFR\n$\\sim$ 1 M$_\\odot$yr$^{-1}$ at $z$ = 6 are detected with F770, which decreases\nto 20% at $z$ = 8. For such galaxies, only 5% of the subsample will be detected\nat 5$\\sigma$ with F770 and F1000 at $z$ = 8, and only 10% with F770, F1000, and\nF1280 at $z$ = 6. The link between dust and star formation is complex, and many\naspects remain to be fully understood. In this context, the JWST will\nrevolutionise the field, allowing investigation of the dust--star interplay\nwell within the epoch of reionisation.", "positive": "Diverse Oxygen Abundance in Early Galaxies Unveiled by Auroral Line\n Analysis with JWST: We present deep JWST NIRSpec observations in the sightline of MACS\nJ1149.5+2223, a massive cluster of galaxies at $z=0.54$. We report the\nspectroscopic redshift of 28 sources at $37$, i.e.\ncomparable to the most metal poor galaxies in the local Universe. The search of\nprimordial galaxies may be accomplished by extending toward a lower mass and/or\nby investigating inhomogeneities at smaller spatial scales. Lastly, we\ninvestigate potential systematics caused by the limitation of JWST's MSA\nobservations. Caution is warranted when the target exceeds the slit size, as\nthis situation could allow an overestimation of ``global\" metallicity,\nespecially under the presence of strong negative metallicity gradient." }, { "anchor": "How does the presence of bar affects the fueling of supermassive black\n holes ? An IllustrisTNG100 perspective: We conduct a statistical study of black hole masses of barred and unbarred\ngalaxies in the IllustrisTNG100 cosmological magneto-hydrodynamical\nsimulations. This work aims to understand the role of the bars in the growth of\ncentral supermassive black hole mass and its implications on AGN fueling. Our\nsample consists of 1191 barred galaxies and 2738 unbarred galaxies in the\nIllustrisTNG100 simulations. To have an unbiased study, we perform our analysis\nwith an equal number of barred and unbarred galaxies by using various\ncontrolled parameters like total galaxy mass, stellar mass, gas mass, dark\nmatter halo mass, etc. Except for the stellar mass controlling, we find that\nthe median of the black hole mass distribution for barred galaxies is higher\nthan that of the unbarred ones indicating that stellar mass is a key parameter\ninfluencing the black hole growth. The higher mean accretion rate of the black\nholes in barred galaxies, averaged since the bar forming epoch (z~2 ), explains\nthe higher mean black hole masses in barred galaxies. Further, we also test\nthat these results are unaffected by other environmental processes like\nminor/major merger histories and neighboring gas density of black hole.\nAlthough the relationship between stellar mass, bar formation, and black hole\ngrowth is complex, with various mechanisms involved, our analysis suggests that\nbars can play a crucial role in feeding black holes, particularly in galaxies\nwith massive stellar disks.", "positive": "On the use of the index N2 to derive the metallicity in metal-poor\n galaxie: The N2 index ([N II]6584/Ha) is used to determine emission line galaxy\nmetallicities at all redshifts, including high redshift, where galaxies tend to\nbe metal-poor. The initial aim of the work was to improve the calibrations used\nto infer oxygen abundance from N2 employing updated low-metallicity galaxy\ndatabases. We compare N2 and the metallicity determined using the direct method\nfor the set of extremely metal-poor galaxies compiled by Morales-Luis et al.\n(2011). To our surprise, the oxygen abundance presents a tendency to be\nconstant with N2, with a very large scatter. Consequently, we find that the\nexisting N2 calibrators overstimate the oxygen abundance for most low\nmetallicity galaxies, and then they can be used only to set upper limits to the\ntrue metallicity in low-metallicity galaxies. An explicit expression for this\nlimit is given. In addition, we try to explain the observed scatter using\nphotoionization models. It is mostly due to the different evolutionary state of\nthe HII regions producing the emission lines, but it also arises due to\ndifferences of N/O among the galaxies." }, { "anchor": "Dense circum-nuclear molecular gas in starburst galaxies: We present results from a study of the dense circum-nuclear molecular gas of\nstarburst galaxies. The study aims to investigate the interplay between\nstarbursts, active galactic nuclei and molecular gas. We characterise the dense\ngas traced by HCN, HCO$^{+}$ and HNC and examine its kinematics in the\ncircum-nuclear regions of nine starburst galaxies observed with the Australia\nTelescope Compact Array. We detect HCN (1$-$0) and HCO$^{+}$ (1$-$0) in seven\nof the nine galaxies and HNC (1$-$0) in four. Approximately 7 arcsec resolution\nmaps of the circum-nuclear molecular gas are presented. The velocity integrated\nintensity ratios, HCO$^{+}$ (1$-$0)/HCN (1$-$0) and HNC (1$-$0)/HCN (1$-$0),\nare calculated. Using these integrated intensity ratios and spatial intensity\nratio maps we identify photon dominated regions (PDRs) in NGC 1097, NGC 1365\nand NGC 1808. We find no galaxy which shows the PDR signature in only one part\nof the observed nuclear region. We also observe unusually strong HNC emission\nin NGC 5236, but it is not strong enough to be consistent with X-ray dominated\nregion (XDR) chemistry. Rotation curves are derived for five of the galaxies\nand dynamical mass estimates of the inner regions of three of the galaxies are\nmade.", "positive": "Phylogenetic Analyses of Quasars and Galaxies: Phylogenetic approaches have proven to be useful in astrophysics. We have\nrecently published a Maximum Parsimony (or cladistics) analysis on two samples\nof 215 and 85 low-z quasars (z < 0.7) which offer a satisfactory coverage of\nthe Eigenvector 1-derived main sequence. Cladistics is not only able to group\nsources radiating at higher Eddington ratios, to separate radio-quiet (RQ) and\nradio-loud (RL) quasars and properly distinguishes core-dominated and\nlobe-dominated quasars, but it suggests a black hole mass threshold for\npowerful radio emission as already proposed elsewhere. An interesting\ninterpretation from this work is that the phylogeny of quasars may be\nrepresented by the ontogeny of their central black hole, i.e. the increase of\nthe black hole mass. However these exciting results are based on a small sample\nof low-z quasars, so that the work must be extended. We are here faced with two\ndifficulties. The first one is the current lack of a larger sample with similar\nobservables. The second one is the prohibitive computation time to perform a\ncladistic analysis on more that about one thousand objects. We show in this\npaper an experimental strategy on about 1500 galaxies to get around this\ndifficulty. Even if it not related to the quasar study, it is interesting by\nitself and opens new pathways to generalize the quasar findings." }, { "anchor": "Splash Bridge Models of Inclined, Gas-Rich, Direct Galaxy Collisions: Splash bridges are formed from the direct inelastic collision of gas-rich\ngalaxies. Recent multi-wavelength observations of the Taffy galaxies, UGC\n12914/15, have revealed complicated gas structures in the bridge. We have\nupgraded the sticky particle simulation code of Yeager et al., 2019, by adding:\nthe ability to adjust the relative inclination of the gas discs, the ability to\ntrack cloud-cloud collisions over time, and additional cooling processes.\nInclination effects lead to various morphological features, including\nfilamentary streams of gas stripped from the smaller galactic disc. The offset\nof disc centres at impact determines whether or not these streams flow in a\nsingle direction or multiple directions, even transverse to the motion of the\ntwo galaxies. We also find that, across many types of direct collision,\nindependent of the inclination or offset, the distributions of weighted Mach\nnumbers and shock velocities in colliding clouds relax to a very similar form.\nThere is good evidence of prolonged turbulence in the gas of each splash bridge\nfor all inclinations and offsets tested, as a result of continuing cloud\ncollisions, which in turn are the result of shearing and differentially\naccelerated trajectories. The number distribution of high velocity shocks in\ncloud collisions, produced in our low inclination models, are in agreement with\nthose observed in the Taffy Galaxies with ALMA, Appleton et al., 2019.", "positive": "Suzaku Observation of the Intermediate Polar V1223 Sagittarii: We report on the Suzaku observation of the intermediate polar V1223\nSagittarii. Using a multi-temperature plasma emission model with its reflection\nfrom a cold matter, we obtained the shock temperature to be 37.9^{+5.1}_{-4.6}\nkeV. This constrains the mass and the radius of the white dwarf (WD) in the\nranges 0.82^{+0.05}_{-0.06} solar masses and (6.9+/-0.4)x10^8 cm, respectively,\nwith the aid of a WD mass-radius relation. The solid angle of the reflector\nviewed from the post-shock plasma was measured to be Omega/2pi = 0.91+/-0.26. A\nfluorescent iron Kalpha emission line is detected, whose central energy is\ndiscovered to be modulated with the WD rotation for the first time in\nmagnetic-CVs. Detailed spectral analysis indicates that the line comprises of a\nstable 6.4 keV component and a red-shifted component, the latter of which\nappears only around the rotational intensity-minimum phase. The equivalent\nwidth (EW) of the former stable component ~80 eV together with the measured\nOmega indicates the major reflector is the WD surface, and the shock height is\nnot more than 7% of the WD radius. Comparing this limitation to the height\npredicted by the Aizu model (1973), we estimated the fractional area onto which\nthe accretion occurs to be < 7x10^{-3}$ of the WD radius, which is the most\nsevere constraint in non-eclipsing IPs. The red-shifted iron line component, on\nthe other hand, can be interpreted as emanating from the pre-shock accretion\nflow via fluorescence. Its EW (28^{+44}_{-13} eV) and the central energy\n(6.30_{-0.05}^{+0.07} keV) at the intensity-minimum phase are consistent with\nthis interpretation." }, { "anchor": "The Spread of Metals into the Low-Redshift Intergalactic Medium: We investigate the association between galaxies and metal-enriched and\nmetal-deficient absorbers in the local universe ($z < 0.16$) using a large\ncompilation of FUV spectra of bright AGN targets observed with the Cosmic\nOrigins Spectrograph aboard the Hubble Space Telescope. In this homogeneous\nsample of 18 O VI detections at $N_{\\rm O\\,{VI}}\\geq13.5~\\mathrm{cm}^{-2}$ and\n18 non-detections at $N_{\\rm O\\,{VI}}<13.5~\\mathrm{cm}^{-2}$ using Lya\nabsorbers with ${N_{\\rm H\\,{I}}\\geq} 10^{14}~\\mathrm{cm}^{-2}$, the maximum\ndistance O VI extends from galaxies of various luminosities is $\\sim0.6$ Mpc,\nor $\\sim5$ virial radii, confirming and refining earlier results. This is an\nimportant value that must be matched by numerical simulations, which input the\nstrength of galactic winds at the sub-grid level. We present evidence that the\nprimary contributors to the spread of metals into the circum- and intergalactic\nmedia are sub-$L^*$ galaxies ($0.25L^*1$, the bar mode is strongly\nunstable and unlike in Newtonian gravity can not be avoided, at least in the\nweak field limit, with increasing the pressure support of the disk.", "positive": "Understanding the spiral structure of the Milky Way using the local\n kinematic groups: We study the spiral arm influence on the solar neighbourhood stellar\nkinematics. As the nature of the Milky Way (MW) spiral arms is not completely\ndetermined, we study two models: the Tight-Winding Approximation (TWA) model,\nwhich represents a local approximation, and a model with self-consistent\nmaterial arms named PERLAS. This is a mass distribution with more abrupt\ngravitational forces. We perform test particle simulations after tuning the two\nmodels to the observational range for the MW spiral arm properties. We explore\nthe effects of the arm properties and find that a significant region of the\nallowed parameter space favours the appearance of kinematic groups. The\nvelocity distribution is mostly sensitive to the relative spiral arm phase and\npattern speed. In all cases the arms induce strong kinematic imprints for\npattern speeds around 17 km/s/kpc (close to the 4:1 inner resonance) but no\nsubstructure is induced close to corotation. The groups change significantly if\none moves only ~0.6 kpc in galactocentric radius, but ~2 kpc in azimuth. The\nappearance time of each group is different, ranging from 0 to more than 1 Gyr.\nRecent spiral arms can produce strong kinematic structures. The stellar\nresponse to the two potential models is significantly different near the Sun,\nboth in density and kinematics. The PERLAS model triggers more substructure for\na larger range of pattern speed values. The kinematic groups can be used to\nreduce the current uncertainty about the MW spiral structure and to test\nwhether this follows the TWA. However, groups such as the observed ones in the\nsolar vicinity can be reproduced by different parameter combinations. Data from\nvelocity distributions at larger distances are needed for a definitive\nconstraint." }, { "anchor": "Connections between galaxy properties and halo formation time in the\n cosmic web: By linking galaxies in Sloan Digital Sky Survey (SDSS) to subhaloes in the\nELUCID simulation, we investigate the relation between subhalo formation time\nand the galaxy properties, and the dependence of galaxy properties on the\ncosmic web environment. We find that central and satellite subhaloes have\ndifferent formation time, where satellite subhaloes are older than central\nsubhaloes at fixed mass. At fixed mass, the galaxy stellar-to-subhalo mass\nratio is a good proxy of the subhalo formation time, and increases with the\nsubhalo formation redshifts, especially for massive galaxies. The subhalo\nformation time is dependent on the cosmic web environment. For central\nsubhaloes, there is a characteristic subhalo mass of $\\sim 10^{12} \\msun$,\nbelow which subhaloes in knots are older than subhaloes of the same mass in\nfilaments, sheets, or voids, while above which it reverses. The cosmic web\nenvironmental dependence of stellar-to-subhalo mass ratio is similar to that of\nthe subhalo formation time. For centrals, there is a characteristic subhalo\nmass of $\\sim 10^{12} \\msun$, below which the stellar-to-subhalo mass ratio is\nhigher in knots than in filaments, sheets and voids, above which it reverses.\nGalaxies in knots have redder colors below $10^{12} \\msun$, while above\n$10^{12} \\msun$, the environmental dependence vanishes. Satellite fraction is\nstrongly dependent on the cosmic web environment, and decreases from knots to\nfilaments to sheets to voids, especially for low-mass galaxies.", "positive": "The life cycle of star cluster in a tidal field: The evolution of globular clusters due to 2-body relaxation results in an\noutward flow of energy and at some stage all clusters need a central energy\nsource to sustain their evolution. Henon provided the insight that we do not\nneed to know the details of the energy production in order to understand the\nrelaxation-driven evolution of the cluster, at least outside the core. He\nprovided two self-similar solutions for the evolution of clusters based on the\nview that the cluster as a whole determines the amount of energy that is\nproduced in the core: steady expansion for isolated clusters, and homologous\ncontraction for clusters evaporating in a tidal field. We combine these models:\nthe half-mass radius increases during the first half of the evolution, and\ndecreases in the second half; while the escape rate approaches a constant value\nset by the tidal field. We refer to these phases as `expansion dominated' and\n`evaporation dominated'. These simple analytical solutions immediately allow us\nto construct evolutionary tracks and isochrones in terms of cluster half-mass\ndensity, cluster mass and galacto-centric radius. From a comparison to the\nMilky Way globular clusters we find that roughly 1/3 of them are in the second,\nevaporation-dominated phase and for these clusters the density inside the\nhalf-mass radius varies with the galactocentric distance R as rho_h ~ 1/R^2.\nThe remaining 2/3 are still in the first, expansion-dominated phase and their\nisochrones follow the environment-independent scaling rho_h ~ M^2; that is, a\nconstant relaxation time-scale. We find substantial agreement between Milky Way\nglobular cluster parameters and the isochrones, which suggests that there is,\nas Henon suggested, a balance between the flow of energy and the central energy\nproduction for almost all globular clusters." }, { "anchor": "Identification of the progenitors of rich clusters and member galaxies\n in rapid formation at z>2: We present the results of near-infrared spectroscopy of H$\\alpha$ emitters\n(HAEs) associated with two protoclusters around radio galaxies (PKS1138-262 at\n$z$=2.2 and USS1558-003 at $z$=2.5) with Multi-Object Infrared Camera and\nSpectrograph (MOIRCS) on the Subaru telescope. Among the HAE candidates\nconstructed from our narrow-band imaging, we have confirmed membership of 27\nand 36 HAEs for the respective protoclusters, with a success rate of 70 per\ncent of our observed targets. The large number of spectroscopically confirmed\nmembers per cluster has enabled us for the first time to reveal the detailed\nkinematical structures of the protoclusters at $z$$>$2. The clusters show\nprominent substructures such as clumps, filaments and velocity gradients,\nsuggesting that they are still in the midst of rapid construction to grow to\nrich clusters at later times. We also estimate dynamical masses of the clusters\nand substructures assuming their local virialization. The inferred masses\n($\\sim$10$^{14}$M$_\\odot$) of the protocluster cores are consistent with being\ntypical progenitors of the present-day most massive class of galaxy clusters\n($\\sim$10$^{15}$M$_\\odot$) if we take into account the typical mass growth\nhistory of clusters. We then calculated the integrated star formation rates of\nthe protocluster cores normalized by the dynamical masses, and compare these\nwith lower redshift descendants. We see a marked increase of star-forming\nactivities in the cluster cores, by almost three orders of magnitude, as we go\nback in time to 11 billion years ago; this scales as (1$+$$z$)$^6$.", "positive": "The JWST Resolved Stellar Populations Early Release Science Program VI.\n Identifying Evolved Stars in Nearby Galaxies: We present an investigation of evolved stars in the nearby star-forming\ngalaxy WLM, using NIRCam imaging from the JWST resolved stellar populations\nearly-release science (ERS) program. We find that various combinations of the\nF090W, F150W, F250M, and F430M filters can effectively isolate red supergiants\n(RSGs) and thermally-pulsing asymptotic giant branch (TP-AGB) stars from one\nanother, while also providing a reasonable separation of the primary TP-AGB\nsubtypes: carbon-rich C-type stars and oxygen-rich M-type stars. The\nclassification scheme we present here agrees very well with the\nwell-established Hubble Space Telescope (HST) medium-band filter technique. The\nratio of C to M-type stars (C/M) is 0.8$\\pm$0.1 for both the new JWST and the\nHST classifications, which is within one sigma of empirical predictions from\noptical narrow-band CN and TiO filters. The evolved star colors show good\nagreement with the predictions from the PARSEC$+$COLIBRI stellar evolutionary\nmodels, and the models indicate a strong metallicity dependence that makes\nstellar identification even more effective at higher metallicity. However, the\nmodels also indicate that evolved star identification with NIRCam may be more\ndifficult at lower metallicies. We test every combination of NIRCam filters\nusing the models and present additional filters that are also useful for\nevolved star studies. We also find that $\\approx$90\\% of the dusty evolved\nstars are carbon-rich, suggesting that carbonaceous dust dominates the\npresent-day dust production in WLM, similar to the findings in the Magellanic\nClouds. These results demonstrate the usefulness of NIRCam in identifying and\nclassifying dust-producing stars without the need for mid-infrared data." }, { "anchor": "H$\u03b1$ kinematics of the isolated interacting galaxy pair KPG 486\n (NGC 6090): In optical images, the not amply studied isolated interacting galaxy pair KPG\n486 (NGC 6090) displays similar features to the galaxy pair The Antennae (NGC\n4038/39). To compare the distribution of ionized hydrogen gas, morphology and\nkinematic and dynamic behaviour between both galaxy pairs, we present\nobservations in the H$\\alpha$ emission line of NGC 6090 acquired with the\nscanning Fabry-Perot interferometer, PUMA. For each galaxy in NGC 6090 we\nobtained several kinematic parameters, its velocity field and its rotation\ncurve, we also analysed some of the perturbations induced by their encounter.\nWe verified the consistency of our results by comparing them with kinematic\nresults from the literature. The comparison of our results on NGC 6090 with\nthose obtained in a previous similar kinematic analysis made for The Antennae\nhighlighted great differences between these galaxy pairs.", "positive": "High-Resolution Radio Image of a Candidate Radio Galaxy at z=5.72: Recently, Saxena et al. (2018) reported the discovery of a possible radio\ngalaxy, J1530$+$1049 at a redshift of z=5.72. We observed the source with the\nEuropean Very Long Baseline Interferometry Network at $1.7$ GHz. We detected\ntwo faint radio features with a separation of $\\sim 400$ mas. The radio power\ncalculated from the VLA flux density by Saxena et al. (2018), and the projected\nsource size derived from our EVN data place J1530$+$1049 among the medium-sized\nsymmetric objects (MSOs) which are thought to be young counterparts of radio\ngalaxies (An and Baan 2012). Thus, our finding is consistent with a radio\ngalaxy in an early phase of its evolution as proposed by Saxena et al. (2018)." }, { "anchor": "Metallicity Gradient of Barred Galaxies with TYPHOON: Bars play an important role in mixing material in the inner regions of\ngalaxies and stimulating radial migration. Previous observations have found\nevidence for the impact of a bar on metallicity gradients but the effect is\nstill inconclusive. We use the TYPHOON/PrISM survey to investigate the\nmetallicity gradients along and beyond the bar region across the entire\nstar-forming disk of five nearby galaxies. Using emission line diagrams to\nidentify star-forming spaxels, we recover the global metallicity gradients\nranging from -0.0162 to -0.073 dex/kpc with evidence that the galactic bars act\nas an agent in affecting in-situ star formation as well as the motions of gas\nand stars. We observe cases with a `shallow-steep' metallicity radial profile,\nwith evidence of the bar flattening the metallicity gradients inside the bar\nregion (NGC~5068 and NGC~1566) and also note instances where the bar appears to\ndrive a steeper metallicity gradient producing `steep-shallow' metallicity\nprofiles (NGC~1365 and NGC~1744). For NGC~2835, a `steep-shallow' metallicity\ngradient break occurs at a distance $\\sim$ 4 times the bar radius, which is\nmore likely driven by gas accretion to the outskirt of the galaxy instead of\nthe bar. The variation of metallicity gradients around the bar region traces\nthe fluctuations of star formation rate surface density in NGC~1365, NGC~1566\nand NGC~1744. A larger sample combined with hydrodynamical simulations is\nrequired to further explore the diversity and the relative importance of\ndifferent ISM mixing mechanisms on the gas-phase metallicity gradients in local\ngalaxies.", "positive": "The velocity distribution of nearby stars from Hipparcos data I. The\n significance of the moving groups: We present a three-dimensional reconstruction of the velocity distribution of\nnearby stars (<~ 100 pc) using a maximum likelihood density estimation\ntechnique applied to the two-dimensional tangential velocities of stars. The\nunderlying distribution is modeled as a mixture of Gaussian components. The\nalgorithm reconstructs the error-deconvolved distribution function, even when\nthe individual stars have unique error and missing-data properties. We apply\nthis technique to the tangential velocity measurements from a kinematically\nunbiased sample of 11,865 main sequence stars observed by the Hipparcos\nsatellite. We explore various methods for validating the complexity of the\nresulting velocity distribution function, including criteria based on Bayesian\nmodel selection and how accurately our reconstruction predicts the radial\nvelocities of a sample of stars from the Geneva-Copenhagen survey (GCS). Using\nthis very conservative external validation test based on the GCS, we find that\nthere is little evidence for structure in the distribution function beyond the\nmoving groups established prior to the Hipparcos mission. This is in sharp\ncontrast with internal tests performed here and in previous analyses, which\npoint consistently to maximal structure in the velocity distribution. We\nquantify the information content of the radial velocity measurements and find\nthat the mean amount of new information gained from a radial velocity\nmeasurement of a single star is significant. This argues for complementary\nradial velocity surveys to upcoming astrometric surveys." }, { "anchor": "Chemical evolution of the Galactic Center: In recent years, the Galactic Center (GC) region (200 pc in radius) has been\nstudied in detail with spectroscopic stellar data as well as an estimate of the\nongoing star formation rate. The aims of this paper are to study the chemical\nevolution of the GC region by means of a detailed chemical evolution model and\nto compare the results with high resolution spectroscopic data in order to\nimpose constraints on the GC formation history.The chemical evolution model\nassumes that the GC region formed by fast infall of gas and then follows the\nevolution of alpha-elements and Fe. We test different initial mass functions\n(IMFs), efficiencies of star formation and gas infall timescales. To reproduce\nthe currently observed star formation rate, we assume a late episode of star\nformation triggered by gas infall/accretion. We find that, in order to\nreproduce the [alpha/Fe] ratios as well as the metallicity distribution\nfunction observed in GC stars, the GC region should have experienced a main\nearly strong burst of star formation, with a star formation efficiency as high\nas 25 Gyr^{-1}, occurring on a timescale in the range 0.1-0.7 Gyr, in agreement\nwith previous models of the entire bulge. Although the small amount of data\nprevents us from drawing firm conclusions, we suggest that the best IMF should\ncontain more massive stars than expected in the solar vicinity, and the last\nepisode of star formation, which lasted several hundred million years, should\nhave been triggered by a modest episode of gas infall/accretion, with a star\nformation efficiency similar to that of the previous main star formation\nepisode. This last episode of star formation produces negligible effects on the\nabundance patterns and can be due to accretion of gas induced by the bar. Our\nresults exclude an important infall event as a trigger for the last starburst.", "positive": "High-resolution, 3D radiative transfer modelling III. The DustPedia\n barred galaxies: Context: Dust in late-type galaxies in the local Universe is responsible for\nabsorbing approximately one third of the energy emitted by stars. It is often\nassumed that dust heating is mainly attributable to the absorption of UV and\noptical photons emitted by the youngest (<= 100 Myr) stars. Consequently,\nthermal re-emission by dust at FIR wavelengths is often linked to the\nstar-formation activity of a galaxy. However, several studies argue that the\ncontribution to dust heating by much older stars might be more significant.\nAdvances in radiation transfer (RT) simulations finally allow us to actually\nquantify the heating mechanisms of diffuse dust by the stellar radiation field.\n Aims: As one of the main goals in the DustPedia project, we have constructed\ndetailed 3D stellar and dust RT models for nearby galaxies. We analyse the\ncontribution of the different stellar populations to the dust heating in four\nface-on barred galaxies: NGC1365, M83, M95, and M100. We aim to quantify the\nfraction directly related to young stars, both globally and on local scales,\nand to assess the influence of the bar on the heating fraction.\n Results: We derive global attenuation laws for each galaxy and confirm that\ngalaxies of high sSFR have shallower attenuation curves and weaker UV bumps. On\naverage, 36.5% of the bolometric luminosity is absorbed by dust. We report a\nclear effect of the bar structure on the radial profiles of the dust-heating\nfraction by the young stars, and the dust temperature. We find that the young\nstars are the main contributors to the dust heating, donating, on average ~59%\nof their luminosity to this purpose throughout the galaxy. This dust-heating\nfraction drops to ~53% in the bar region and ~38% in the bulge region where the\nold stars are the dominant contributors to the dust heating. We also find a\nstrong link between the heating fraction by the young stars and the sSFR." }, { "anchor": "Sgr A* flares: tidal disruption of asteroids and planets?: It is theoretically expected that a supermassive black hole (SMBH) in the\ncentre of a typical nearby galaxy disrupts a Solar-type star every ~ 10^5\nyears, resulting in a bright flare lasting for months. Sgr A*, the resident\nSMBH of the Milky Way, produces (by comparison) tiny flares that last only\nhours but occur daily. Here we explore the possibility that these flares could\nbe produced by disruption of smaller bodies - asteroids. We show that asteroids\npassing within an AU of Sgr A* could be split into smaller fragments which then\nvaporise by bodily friction with the tenuous quiescent gas accretion flow onto\nSgr A*. The ensuing shocks and plasma instabilities may create a transient\npopulation of very hot electrons invoked in several currently popular models\nfor Sgr A* flares, thus producing the required spectra. We estimate that\nasteroids larger than ~ 10 km in size are needed to power the observed flares,\nwith the maximum possible luminosity of the order 10^39 erg s^-1. Assuming that\nthe asteroid population per parent star in the central parsec of the Milky Way\nis not too dissimilar from that around stars in the Solar neighbourhood, we\nestimate the asteroid disruption rates, and the distribution of the expected\nluminosities, finding a reasonable agreement with the observations. We also\nnote that planets may be tidally disrupted by Sgr A* as well, also very\ninfrequently. We speculate that one such disruption may explain the putative\nincrease in Sgr A* luminosity ~ 300 yr ago.", "positive": "The \"Maggie\" filament: Physical properties of a giant atomic cloud: The atomic phase of the interstellar medium plays a key role in the formation\nprocess of molecular clouds. Due to the line-of-sight confusion in the Galactic\nplane that is associated with its ubiquity, atomic hydrogen emission has been\nchallenging to study. Employing the high-angular resolution data from the THOR\nsurvey, we identify one of the largest, coherent, mostly atomic HI filaments in\nthe Milky Way at the line-of-sight velocities around -54 km/s. The giant atomic\nfilament \"Maggie\", with a total length of 1.2 kpc, is not detected in most\nother tracers, and does not show signs of active star formation. At a kinematic\ndistance of 17 kpc, Maggie is situated below (by 500 pc) but parallel to the\nGalactic HI disk and is trailing the predicted location of the Outer Arm by\n5-10 km/s in longitude-velocity space. The centroid velocity exhibits a smooth\ngradient of less than $\\pm$3 km/s /10 pc and a coherent structure to within\n$\\pm$6 km/s. The line widths of 10 km/s along the spine of the filament are\ndominated by non-thermal effects. After correcting for optical depth effects,\nthe mass of Maggie's dense spine is estimated to be $7.2\\times10^5\\,M_{\\odot}$.\nThe mean number density of the filament is 4$\\rm\\,cm^{-3}$, which is best\nexplained by the filament being a mix of cold and warm neutral gas. In contrast\nto molecular filaments, the turbulent Mach number and velocity structure\nfunction suggest that Maggie is driven by transonic to moderately supersonic\nvelocities that are likely associated with the Galactic potential rather than\nbeing subject to the effects of self-gravity or stellar feedback. The column\ndensity PDF displays a log-normal shape around a mean of $N_{\\rm HI} =\n4.8\\times 10^{20}\\rm\\,cm^{-2}$, thus reflecting the absence of dominating\neffects of gravitational contraction." }, { "anchor": "HI, CO, and Dust in the Perseus Cloud: Comparison analyses between the gas emission data (HI 21cm line and CO 2.6 mm\nline) and the Planck/IRAS dust emission data (optical depth at 353 GHz tau353\nand dust temperature Td) allow us to estimate the amount and distribution of\nthe hydrogen gas more accurately, and our previous studies revealed the\nexistence of a large amount of optically-thick HI gas in the solar\nneighborhood. Referring to this, we discuss the neutral hydrogen gas around the\nPerseus cloud in the present paper. By using the J-band extinction data, we\nfound that tau353 increases as a function of the 1.3-th power of column number\ndensity of the total hydrogen (NH), and this implies dust evolution in high\ndensity regions. This calibrated tau353-NH relationship shows that the amount\nof the HI gas can be underestimated to be ~60% if the optically-thin HI method\nis used. Based on this relationship, we calculated optical depth of the 21 cm\nline (tauHI), and found that ~ 0.92 around the molecular cloud. The\neffect of tauHI is still significant even if we take into account the dust\nevolution. We also estimated a spatial distribution of the CO-to-H2 conversion\nfactor (XCO), and we found its average value is ~ 1.0x10^20 cm-2 K-1 km-1\ns. Although these results are inconsistent with some previous studies, these\ndiscrepancies can be well explained by the difference of the data and analyses\nmethods.", "positive": "The cosmic growth of the active black hole population at 192\\%$ of\nsources), while 74$\\%$ of sources are coincident with a stellar association\ndefined in the HST data. Using SED fitting, we find that the stellar masses of\nthe 21 $\\mu$m sources span a range of 10$^{2}$ to 10$^{4}~M_\\odot$ with\nmass-weighted ages down to 2 Myr. There is a tight correlation between\nattenuation-corrected H$\\alpha$ and 21 $\\mu$m luminosity for\n$L_{\\nu,\\mathrm{F2100W}}>10^{19}~\\mathrm{W~Hz}^{-1}$. Young embedded source\ncandidates selected at 21 $\\mu$m are found below this threshold and have\n$M_\\star < 10^{3}~M_\\odot$." }, { "anchor": "Damped perturbations in stellar systems: Genuine modes and Landau-damped\n waves: This research was stimulated by the recent studies of damping solutions in\ndynamically stable spherical stellar systems. Using the simplest model of the\nhomogeneous stellar medium, we discuss nontrivial features of stellar systems.\nTaking them into account will make it possible to correctly interpret the\nresults obtained earlier and will help to set up decisive numerical experiments\nin the future. In particular, we compare the initial value problem versus the\neigenvalue problem. It turns out that in the unstable regime, the Landau-damped\nwaves can be represented as a superposition of van Kampen modes {\\it plus} a\ndiscrete damped mode, usually ignored in the stability study. This mode is a\nsolution complex conjugate to the unstable Jeans mode. In contrast, the\nLandau-damped waves are not genuine modes: in modes, eigenfunctions depend on\ntime as $\\exp (-{\\rm i} \\omega t)$, while the waves do not have eigenfunctions\non the real $v$-axis at all. However, `eigenfunctions' on the complex\n$v$-contours do exist. Deviations from the Landau damping are common and can be\ndue to singularities or cut-off of the initial perturbation above some fixed\nvalue in the velocity space.", "positive": "SPIRE Spectroscopy of Early Type Galaxies: We present SPIRE spectroscopy for 9 early-type galaxies (ETGs) representing\nthe most CO-rich and far-infrared (FIR) bright galaxies of the volume-limited\nAtlas3D sample. Our data include detections of mid to high J CO transitions\n(J=4-3 to J=13-12) and the [CI] (1-0) and (2-1) emission lines. CO spectral\nline energy distributions (SLEDs) for our ETGs indicate low gas excitation,\nbarring NGC 1266. We use the [CI] emission lines to determine the excitation\ntemperature of the neutral gas, as well as estimate the mass of molecular\nhydrogen. The masses agree well with masses derived from CO, making this\ntechnique very promising for high redshift galaxies. We do not find a trend\nbetween the [NII] 205 flux and the infrared luminosity, but we do find that the\n[NII] 205/CO(6-5) line ratio is correlated with the 60/100 $\\mu$m Infrared\nAstronomical Satellite (IRAS) colors. Thus the [NII] 205/CO(6-5) ratio can be\nused to infer a dust temperature, and hence the intensity of the interstellar\nradiation field (ISRF). Photodissociation region (PDR) models show that use of\n[CI] and CO lines in addition to the typical [CII], [OI], and FIR fluxes drive\nthe model solutions to higher densities and lower values of G$_0$. In short,\nthe SPIRE lines indicate that the atomic and molecular gas in the CO-rich ETGs\nhave similar properties to other galaxies. As might be expected from their low\nlevels of star formation activity, the ETGs have rather low excitation CO\nSLEDs, low temperatures inferred from the [CI] lines, and modestly lower\n[CI]/CO ratios." }, { "anchor": "High-redshift galaxies and low-mass stars: The sensitivity available to near-infrared surveys has recently allowed us to\nprobe the galaxy population at $z\\approx 7$ and beyond. The existing {\\em\nHubble} Wide Field Camera 3 (WFC3) and the Visible and Infrared Survey\nTelescope for Astronomy (VISTA) Infrared Camera (VIRCam) instruments allow deep\nsurveys to be undertaken well beyond one micron - a capability that will be\nfurther extended with the launch and commissioning of the {\\em James Webb Space\nTelescope (JWST)}. As new regions of parameter space in both colour and depth\nare probed new challenges for distant galaxy surveys are identified. In this\npaper we present an analysis of the colours of L and T dwarf stars in widely\nused photometric systems. We also consider the implications of the\nnewly-identified Y dwarf population - stars that are still cooler and less\nmassive than T dwarfs for both the photometric selection and spectroscopic\nfollow-up of faint and distant galaxies. We highlight the dangers of working in\nthe low-signal-to-noise regime, and the potential contamination of existing and\nfuture samples. We find that {\\em Hubble}/WFC3 and VISTA/VIRCam $Y$-drop\nselections targeting galaxies at $z\\sim7.5$ are vulnerable to contamination\nfrom T and Y class stars. Future observations using {\\em JWST}, targeting the\n$z\\sim7$ galaxy population, are also likely to prove difficult without deep\nmedium-band observations. We demonstrate that single emission line detections\nin typical low signal-to-noise spectroscopic observations may also be suspect,\ndue to the unusual spectral characteristics of the cool dwarf star population.", "positive": "Radial Migration in Disk Galaxies I: Transient Spiral Structure and\n Dynamics: We seek to understand the origin of radial migration in spiral galaxies by\nanalyzing in detail the structure and evolution of an idealized, isolated\ngalactic disk. To understand the redistribution of stars, we characterize the\ntime-evolution of properties of spirals that spontaneously form in the disk.\nOur models unambiguously show that in such disks, single spirals are unlikely,\nbut that a number of transient patterns may coexist in the disk. However, we\nalso show that while spirals are transient in amplitude, at any given time the\ndisk favors patterns of certain pattern speeds. Using several runs with\ndifferent numerical parameters we show that the properties of spirals that\noccur spontaneously in the disk do not sensitively depend on resolution. The\nexistence of multiple transient patterns has large implications for the orbits\nof stars in the disk, and we therefore examine the resonant scattering\nmechanisms that profoundly alter angular momenta of individual stars. We\nconfirm that the corotation scattering mechanism described by Sellwood & Binney\n(2002) is responsible for the largest angular momentum changes in our\nsimulations." }, { "anchor": "Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers A\n method to determine molecular gas properties in luminous galaxies: We present fluxes in both neutral carbon [CI] lines at the centers of 76\ngalaxies with FIR luminosities between 10^{9} and 10^{12} L(o) obtained with\nHerschel-SPIRE and with ground-based facilities, along with the J=7-6, J=4-3,\nJ=2-1 12CO and J=2-1 13CO line fluxes. We investigate whether these lines can\nbe used to characterize the molecular ISM of the parent galaxies in simple ways\nand how the molecular gas properties define the model results. In most\nstarburst galaxies, the [CI]/13CO flux ratio is much higher than in Galactic\nstar-forming regions, and it is correlated to the total FIR luminosity. The\n[CI](1-0)/CO(4-3), the [CI](2-1) (2-1)/CO(7-6), and the [CI] (2-1)/(1-0) flux\nratios are also correlated, and trace the excitation of the molecular gas. In\nthe most luminous infrared galaxies (LIRGs), the ISM is fully dominated by\ndense and moderately warm gas clouds that appear to have low [C]/[CO] and\n[13CO]/[12CO] abundances. In less luminous galaxies, emission from gas clouds\nat lower densities becomes progressively more important, and a multiple-phase\nanalysis is required to determine consistent physical characteristics. Neither\nthe CO nor the [CI] velocity-integrated line fluxes are good predictors of H2\ncolumn densities in individual galaxies, and X(CI) conversion factors are not\nsuperior to X(CO) factors. The methods and diagnostic diagrams outlined in this\npaper also provide a new and relatively straightforward means of deriving the\nphysical characteristics of molecular gas in high-redshift galaxies up to z=5,\nwhich are otherwise hard to determine.", "positive": "Deep ALMA imaging of the merger NGC1614 - Is CO tracing a massive inflow\n of non-starforming gas?: Observations of the molecular gas over scales of 0.5 to several kpc provide\ncrucial information on how gas moves through galaxies, especially in mergers\nand interacting systems, where it ultimately reaches the galaxy center,\naccumulates, and feeds nuclear activity. Studying the processes involved in the\ngas transport is an important step forward to understand galaxy evolution.\n12CO, 13CO and C18O1-0 high-sensitivity ALMA observations were used to assess\nproperties of the large-scale molecular gas reservoir and its connection to the\ncircumnuclear molecular ring in NGC1614. The role of excitation and abundances\nwere studied in this context. Spatial distributions of the 12CO and 13CO\nemission show significant differences. 12CO traces the large-scale molecular\ngas reservoir, associated with a dust lane that harbors infalling gas. 13CO\nemission is - for the first time - detected in the large-scale dust lane. Its\nemission peaks between dust lane and circumnuclear molecular ring. A\n12CO-to-13CO1-0 intensity ratio map shows high values in the ring region (~30)\ntypical for the centers of luminous galaxy mergers and even more extreme values\nin the dust lane (>45). This drop in ratio is consistent with molecular gas in\nthe dust lane being in a diffuse, unbound state while being funneled towards\nthe nucleus. We find a high 16O-to-18O abundance ratio in the starburst region\n(>900), typical of quiescent disk gas - by now, the starburst is expected to\nhave enriched the nuclear ISM in 18O relative to 16O. The massive inflow of gas\nmay be partially responsible for the low 18O/16O abundance since it will dilute\nthe starburst enrichment with unprocessed gas from greater radii. The\n12CO-to-13CO abundance is consistent with this scenario. It suggests that the\nnucleus of NGC1614 is in a transient phase of evolution where starburst and\nnuclear growth are fuelled by returning gas from the minor merger event." }, { "anchor": "HST/WFC3 grism observations of $z~\\mathtt{\\sim}~1$ clusters: The cluster\n vs. field stellar mass-size relation and evidence for size growth of\n quiescent galaxies from minor mergers: Minor mergers are thought to be responsible for the size growth of quiescent\nfield galaxies with decreasing redshift. We test this hypothesis using the\ncluster environment as a laboratory. Satellite galaxies in clusters move at\nhigh velocities, making mergers between them rare. The stellar mass-size\nrelation in ten clusters and in the field is measured and compared at\n$z~\\mathtt{\\sim}~1$. Our cluster sample contains 344\nspectroscopically-confirmed cluster members with Gemini/GMOS and 182 confirmed\nwith HST WFC3 G141 grism spectroscopy. On average, quiescent and star-forming\ncluster galaxies are smaller than their field counterparts by ($0.08\\pm0.04$)\ndex and ($0.07\\pm0.01$) dex respectively. These size offsets are consistent\nwith the average sizes of quiescent and star-forming field galaxies between\n$1.2\\leqslant z\\leqslant1.5$, implying the cluster environment has inhibited\nsize growth between this period and $z~\\mathtt{\\sim}~1$. The negligible\ndifferences measured between the $z~\\mathtt{\\sim}~0$ field and cluster\nquiescent mass-size relations in other works imply that the average size of\nquiescent cluster galaxies must rise with decreasing redshift. Using a toy\nmodel, we show that the disappearance of the compact cluster galaxies might be\nexplained if, on average, $\\mathtt{\\sim}40\\%$ of them merge with their\nbrightest cluster galaxies (BCGs) and $\\mathtt{\\sim}60\\%$ are tidally destroyed\ninto the intra-cluster light (ICL) between $0\\leqslant z\\leqslant1$. This is in\nagreement with the observed stellar mass growth of BCGs between $0\\leqslant\nz\\leqslant1$ and the observed ICL stellar mass fraction at $z~\\mathtt{\\sim}~0$.\nOur results support minor mergers as the cause for the size growth in quiescent\nfield galaxies, with cluster-specific processes responsible for the similarity\nbetween the field and cluster quiescent mass-size relations at low redshift.", "positive": "Star formation concentration as a tracer of environmental quenching in\n action: a study of the Eagle and C-Eagle simulations: We study environmental quenching in the Eagle}/C-Eagle cosmological\nhydrodynamic simulations over the last 11 Gyr (i.e. $z=0-2$). The simulations\nare compared with observations from the SAMI Galaxy Survey at $z=0$. We focus\non satellite galaxies in galaxy groups and clusters ($10^{12}\\,\\rm M_{\\odot}$\n$\\lesssim$ $M_{200}$ < $3 \\times 10^{15}\\, \\rm M_{\\odot}$). A star-formation\nconcentration index [$C$-index $= \\log_{10}(r_\\mathrm{50,SFR} /\nr_\\mathrm{50,rband})$] is defined, which measures how concentrated star\nformation is relative to the stellar distribution. Both Eagle/C-Eagle and SAMI\nshow a higher fraction of galaxies with low $C$-index in denser environments at\n$z=0-0.5$. Low $C$-index galaxies are found below the SFR-$M_{\\star}$ main\nsequence (MS), and display a declining specific star formation rate (sSFR) with\nincreasing radii, consistent with ``outside-in'' environmental quenching.\nAdditionally, we show that $C$-index can be used as a proxy for how long\ngalaxies have been satellites. These trends become weaker at increasing\nredshift and are absent by $z=1-2$. We define a quenching timescale $t_{\\rm\nquench}$ as how long it takes satellites to transition from the MS to the\nquenched population. We find that simulated galaxies experiencing\n``outside-in'' environmental quenching at low redshift ($z=0\\sim0.5$) have a\nlong quenching timescale (median $t_{\\rm quench}$ > 2 Gyr). The simulated\ngalaxies at higher redshift ($z=0.7\\sim2$) experience faster quenching (median\n$t_{\\rm quench}$ < 2Gyr). At $z\\gtrsim 1-2$ galaxies undergoing environmental\nquenching have decreased sSFR across the entire galaxy with no ``outside-in''\nquenching signatures and a narrow range of $C$-index, showing that on average\nenvironmental quenching acts differently than at $z\\lesssim 1$." }, { "anchor": "Updated radial velocities and new constraints on the nature of the\n unseen source in NGC1850 BH1: A black hole candidate orbiting a luminous star in the Large Magellanic Cloud\nyoung cluster NGC 1850 ($\\sim100$Myr) has recently been reported based on\nradial velocity and light curve modelling. Subsequently, an alternative\nexplanation has been suggested for the system: a bloated post-mass transfer\nsecondary star (M$_{\\rm initial} \\sim 4-5M_{\\odot}$, M$_{\\rm current} \\sim\n1-2M_{\\odot}$) with a more massive, yet luminous companion (the primary). Upon\nreanalysis of the MUSE spectra, we found that the radial velocity variations\noriginally reported were underestimated ($K_{\\rm 2,revised} = 176\\pm3$km/s vs\n$K_{\\rm 2,original} = 140\\pm3$km/s) because of the weighting scheme adopted in\nthe full-spectrum fitting analysis. The increased radial velocity\nsemi-amplitude translates into a system mass function larger than previously\ndeduced ($f_{\\rm revised}$=2.83$M_{\\odot}$ vs $f_{\\rm\noriginal}$=1.42$M_{\\odot}$). By exploiting the spectral disentangling\ntechnique, we place an upper limit of 10\\% of a luminous primary source to the\nobserved optical light in NGC1850 BH1, assuming that the primary and secondary\nare the only components contributing to the system. Furthermore, by analysing\narchival near-infrared data, we find clues to the presence of an accretion disk\nin the system. These constraints support a low-mass post-mass transfer star but\ndo not provide a definitive answer whether the unseen component in NGC1850 BH1\nis indeed a black hole. These results predict a scenario where, if a primary\nluminous source of mass M $\\ge 4.7M_{\\odot}$, is present in the system (given\nthe inclination and secondary mass constraints), it must be hidden in a\noptically thick disk to be undetected in the MUSE spectra.", "positive": "Perturbations of Intermediate-mass Black Holes on Stellar Orbits in the\n Galactic Center: We study the short- and long-term effects of an intermediate mass black hole\n(IMBH) on the orbits of stars bound to the supermassive black hole (SMBH) at\nthe center of the Milky Way. A regularized N-body code including post-Newtonian\nterms is used to carry out direct integrations of 19 stars in the S-star\ncluster for 10 Myr. The mass of the IMBH is assigned one of four values from\n400 Msun to 4000 Msun, and its initial semi-major axis with respect to the SMBH\nis varied from 0.3-30 mpc, bracketing the radii at which inspiral of the IMBH\nis expected to stall. We consider two values for the eccentricity of the\nIMBH/SMBH binary, e=(0,0.7), and 12 values for the orientation of the binary's\nplane. Changes at the level of 1% in the orbital elements of the S-stars could\noccur in just a few years if the IMBH is sufficiently massive. On time scales\nof 1 Myr or longer, the IMBH efficiently randomizes the eccentricities and\norbital inclinations of the S-stars. Kozai oscillations are observed when the\nIMBH lies well outside the orbits of the stars. Perturbations from the IMBH can\neject stars from the cluster, producing hypervelocity stars, and can also\nscatter stars into the SMBH; stars with high initial eccentricities are most\nlikely to be affected in both cases. The distribution of S-star orbital\nelements is significantly altered from its currently-observed form by IMBHs\nwith masses greater than 1000 Msun if the IMBH/SMBH semi-major axis lies in the\nrange 3-10 mpc. We use these results to further constrain the allowed\nparameters of an IMBH/SMBH binary at the Galactic center." }, { "anchor": "Improving Damped Random Walk parameters for SDSS Stripe 82 Quasars with\n Pan-STARRS1: We use the Panoramic Survey Telescope and Rapid Response System 1 Survey\n(Pan-STARRS1, PS1) data to extend the Sloan Digital Sky Survey (SDSS) Stripe 82\nquasar light curves. Combining PS1 and SDSS light curves provides a 15 yr\nbaseline for 9248 quasars - 5 yr longer than prior studies that used only SDSS.\nWe fit the light curves with the damped random walk (DRW) model model - a\nstatistical description of their variability. We correlate the resulting DRW\nmodel parameters: asymptotic variability amplitude SF$_{\\infty}$, and\ncharacteristic timescale $\\tau$, with quasar physical properties - black hole\nmass, bolometric luminosity, and redshift. Using simulated light curves, we\nfind that a longer baseline allows us to better constrain the DRW parameters.\nAfter adding PS1 data, the variability amplitude is a stronger function of the\nblack hole mass, and has a weaker dependence on quasar luminosity. In addition,\nthe characteristic timescale $\\tau$ dependence on quasar luminosity is\nmarginally weaker. We also make predictions for the fidelity of DRW model\nparameter retrieval when light curves will be further extended with Zwicky\nTransient Facility (ZTF) and the Rubin Observatory Legacy Survey of Space and\nTime (LSST) data. Finally, we show how updated DRW parameters offer an\nindependent method of discovering changing-look quasar candidates (CLQSOs). The\ncandidates are outliers in terms of differences in magnitude and scatter\nbetween SDSS and PS1 segments. We identify 40 objects (35 newly reported) with\ntenfold increase in variability timescale between SDSS and SDSS--PS1 data,\nwhich is due to a large change in brightness (over 0.5 mag) - characteristic\nfor CLQSOs.", "positive": "The Large Magellanic Cloud and the Distance Scale: The Magellanic Clouds, especially the Large Magellanic Cloud, are places\nwhere multiple distance indicators can be compared with each other in a\nstraight-forward manner at considerable precision. We here review the distances\nderived from Cepheids, Red Variables, RR Lyraes, Red Clump Stars and Eclipsing\nBinaries, and show that the results from these distance indicators generally\nagree to within their errors, and the distance modulus to the Large Magellanic\nCloud appears to be defined to 3% with a mean value of 18.48 mag, corresponding\nto 49.7 Kpc. The utility of the Magellanic Clouds in constructing and testing\nthe distance scale will remain as we move into the era of Gaia." }, { "anchor": "Strong Dark Matter Self-interactions Diversify Halo Populations within\n and surrounding the Milky Way: We perform a high-resolution cosmological zoom-in simulation of a Milky Way\n(MW)--like system, which includes a realistic Large Magellanic Cloud analog,\nusing a large differential elastic dark matter self-interaction cross section\nthat reaches $\\approx 100~\\mathrm{cm}^2\\ \\mathrm{g}^{-1}$ at relative\nvelocities of $\\approx 10~\\mathrm{km\\ s}^{-1}$, motivated by the diverse and\norbitally dependent central densities of dwarf galaxies within and surrounding\nthe MW. We explore the effects of dark matter self-interactions on satellite,\nsplashback, and isolated halos through their abundance, central densities,\nmaximum circular velocities, orbital parameters, and correlations between these\nvariables. We use an effective constant cross section model to analytically\npredict the stages of our simulated halos' gravothermal evolution,\ndemonstrating that deviations from the collisionless $R_{\\rm max}$--$V_{\\rm\nmax}$ relation can be used to select deeply core-collapsed halos, where $V_{\\rm\nmax}$ is a halo's maximum circular velocity, and $R_{\\rm max}$ is the radius at\nwhich it occurs. We predict that a sizable fraction ($\\approx 20\\%$) of\nsubhalos with masses down to $\\approx 10^8~M_{\\odot}$ is deeply core collapsed\nin our SIDM model. Core-collapsed systems form $\\approx 10\\%$ of the isolated\nhalo population down to the same mass; these isolated, core-collapsed halos\nwould host faint dwarf field galaxies with extremely steep central density\nprofiles. Finally, most halos with masses above $\\approx 10^9~M_{\\odot}$ are\ncore-forming in our simulation. Our study thus demonstrates how\nself-interactions diversify halo populations in an environmentally dependent\nfashion within and surrounding MW-mass hosts, providing a compelling avenue to\naddress the diverse dark matter distributions of observed dwarf galaxies.", "positive": "Keplerian rotation of our Galaxy?: It is common to attribute a flat rotation curve to our Galaxy. However\nGalazutdinov et al. (2015) in a recent paper have obtained a Keplerian rotation\ncurve for interstellar clouds in outer parts of the Galaxy. They have\ncalculated the distances from equivalent widths of interstellar CaII lines. The\nradial velocity was also measured on the interstellar CaII absorption line.\n We verify the result by Galazutdinov et al. (2015) basing on observations of\nold open clusters. We propose, that the observations of flat and Keplerian\nrotation curves may be caused by the assumption of circular orbits. The\napplication of formulas derived with the assumption of circular orbits to\nelliptical ones may mimics the flat rotation curve. The interstellar clouds\nwith cross-sections larger than stars may have almost circular orbits, and the\nderived rotation curve will be Keplerian." }, { "anchor": "Discovery of Star Formation in the Extreme Outer Galaxy Possibly Induced\n by a High-velocity Cloud Impact: We report the discovery of star formation activity in perhaps the most\ndistant molecular cloud in the extreme outer galaxy. We performed deep near\ninfrared imaging with the Subaru 8.2 m telescope, and found two young embedded\nclusters at two CO peaks of Digel Cloud 1 at the kinematic distance of D = 16\nkpc (Galactocentric radius RG = 22 kpc). We identified 18 and 45 cluster\nmembers in the two peaks, and the estimated stellar density are ~ 5 and ~ 3\npc^-2, respectively. The observed K-band luminosity function suggests that the\nage of the clusters is less than 1 Myr and also the distance to the clusters is\nconsistent with the kinematic distance. On the sky, Cloud 1 is located very\nclose to the H I peak of high-velocity cloud (HVC) Complex H, and there are\nsome H I intermediate velocity structures between the Complex H and the\nGalactic disk, which could indicate an interaction between them. We suggest\npossibility that Complex H impacting on the Galactic disk has triggered star\nformation in Cloud 1 as well as the formation of Cloud 1 molecular cloud.", "positive": "On the radial acceleration of disk galaxies: The physical processes defining the dynamics of disk galaxies are still\npoorly understood. Hundreds of articles have appeared in the literature over\nthe last decades without arriving at an understanding within a consistent\ngravitational theory. Dark matter (DM) scenarios or a modification of Newtonian\ndynamics (MOND) are employed to model the non-Keplerian rotation curves in most\nof the studies, but the nature of DM and its interaction with baryonic matter\nremains an open question and MOND formulates a mathematical concept without a\nphysical process. We have continued our attempts to use the impact theory of\ngravitation for a description of the peculiar acceleration and velocity curves\nand have considered five more galaxies. Using published data of the galaxies\nNGC 3198, NGC 2403, NGC 1090, UGC 3205 and NGC 1705, it has been possible to\nfind good fits without DM for the observed disk velocities and, as example,\nalso for the extraplanar matter of NGC 3198." }, { "anchor": "The Milky Way's Disk of Classical Satellite Galaxies in Light of Gaia\n DR2: We study the correlation of orbital poles of the 11 classical satellite\ngalaxies of the Milky Way, comparing results from previous proper motions with\nthe independent data by Gaia DR2. Previous results on the degree of correlation\nand its significance are confirmed by the new data. A majority of the\nsatellites co-orbit along the Vast Polar Structure, the plane (or disk) of\nsatellite galaxies defined by their positions. The orbital planes of eight\nsatellites align to $<20^\\circ$ with a common direction, seven even orbit in\nthe same sense. Most also share similar specific angular momenta, though their\nwide distribution on the sky does not support a recent group infall or\nsatellites-of-satellites origin. The orbital pole concentration has\ncontinuously increased as more precise proper motions were measured, as\nexpected if the underlying distribution shows true correlation that is washed\nout by observational uncertainties. The orbital poles of the up to seven most\ncorrelated satellites are in fact almost as concentrated as expected for the\nbest-possible orbital alignment achievable given the satellite positions.\nCombining the best-available proper motions substantially increases the tension\nwith $\\Lambda$CDM cosmological expectations: <0.1 per cent of simulated\nsatellite systems in IllustrisTNG contain seven orbital poles as closely\naligned as observed. Simulated systems that simultaneously reproduce the\nconcentration of orbital poles and the flattening of the satellite distribution\nhave a frequency of <0.1 per cent for any number of k > 3 combined orbital\npoles, indicating that these results are not affected by a look-elsewhere\neffect. This compounds the Planes of Satellite Galaxies Problem.", "positive": "The accretion history of high-mass stars: An ArT\u00e9MiS pilot study of\n Infrared Dark Clouds: The mass growth of protostars is a central element to the determination of\nfundamental stellar population properties such as the initial mass function.\nConstraining the accretion history of individual protostars is therefore an\nimportant aspect of star formation research. The goal of the study presented\nhere is to determine whether high-mass (proto)stars gain their mass from a\ncompact (<0.1pc) fixed-mass reservoir of gas, often referred to as dense cores,\nin which they are embedded, or whether the mass growth of high-mass stars is\ngoverned by the dynamical evolution of the parsec-scale clump that typically\nsurrounds them. To achieve this goal, we performed a 350micron continuum\nmapping of 11 infrared dark clouds, along side some of their neighbouring\nclumps, with the ArT\\'eMiS camera on APEX. By identifying about 200 compact\nArT\\'eMiS sources, and matching them with Herschel Hi-GAL 70micron sources, we\nhave been able to produce mass vs. temperature diagrams. We compare the nature\n(i.e. starless or protostellar) and location of the ArT\\'eMiS sources in these\ndiagrams with modelled evolutionary tracks of both core-fed and clump-fed\naccretion scenarios. We argue that the latter provide a better agreement with\nthe observed distribution of high-mass star-forming cores. However, a robust\nand definitive conclusion on the question of the accretion history of high-mass\nstars requires larger number statistics." }, { "anchor": "Ionization fraction and the enhanced sulfur chemistry in Barnard 1: Barnard B1b has revealed as one of the most interesting globules from the\nchemical and dynamical point of view. It presents a rich molecular chemistry\ncharacterized by large abundances of deuterated and complex molecules.\nFurthermore, it hosts an extremely young Class 0 object and one candidate to\nFirst Hydrostatic Core (FHSC). Our aim was to determine the cosmic ray\nionization rate and the depletion factors in this extremely young star forming\nregion. We carried out a spectral survey towards Barnard 1b as part of the IRAM\nLarge program ASAI using the IRAM 30-m telescope at Pico Veleta (Spain). This\nprovided a very complete inventory of neutral and ionic C-, N- and S- bearing\nspecies with, up to our knowledge, the first secure detections of the\ndeuterated ions DCS+ and DOCO+. We used a state-of-the-art\npseudo-time-dependent gas-phase chemical model to determine the value of the\ncosmic ray ionization rate and the depletion factors. The observational data\nwere well fitted with $\\zeta_{H_2}$ between 3E-17 s$^{-1}$ and 1E-16 s$^{-1}$.\nElemental depletions were estimated to be ~10 for C and O, ~1 for N and ~25 for\nS. Barnard B1b presents similar depletions of C and O than those measured in\npre-stellar cores. The depletion of sulfur is higher than that of C and O but\nnot as extreme as in cold cores. In fact, it is similar to the values found in\nsome bipolar outflows, hot cores and photon-dominated regions. Several\nscenarios are discussed to account for these peculiar abundances. We propose\nthat it is the consequence of the initial conditions (important outflows and\nenhanced UV fields in the surroundings) and a rapid collapse (~0.1 Myr) that\npermits to maintain most S- and N-bearing species in gas phase to great optical\ndepths. The interaction of the compact outflow associated with B1b-S with the\nsurrounding material could enhance the abundances of S-bearing molecules, as\nwell.", "positive": "Clumpiness of Observed and Simulated Cold Circumgalactic Gas: Determining the clumpiness of matter around galaxies is pivotal to a full\nunderstanding of the spatially inhomogeneous, multi-phase gas in the\ncircumgalactic medium (CGM). We combine high spatially resolved 3D observations\nwith hydrodynamical cosmological simulations to measure the cold circumgalactic\ngas clumpiness. We present new adaptive-optics-assisted VLT/MUSE observations\nof a quadruply lensed quasar, targeting the CGM of 2 foreground $z\\sim$1\ngalaxies observed in absorption. We additionally use zoom-in FOGGIE simulations\nwith exquisite resolution ($\\sim$0.1 kpc scales) in the CGM of galaxies to\ncompute the physical properties of cold gas traced by Mg\\,II absorbers. By\ncontrasting these mock-observables with the VLT/MUSE observations, we find a\nlarge spread of fractional variations of Mg\\,II equivalent widths with physical\nseparation, both in observations and simulations. The simulations indicate a\ndependence of the Mg\\,II coherence length on the underlying gas morphology\n(filaments vs clumps). The $z_{\\rm abs}$=1.168 Mg\\,II system shows coherence\nover $\\gtrsim$ 6 kpc and is associated with an [O\\,II] emitting galaxy situated\n89 kpc away, with SFR $\\geq$ 4.6 $\\pm$ {1.5} $\\rm M_{\\odot}$/yr and\n$M_{*}=10^{9.6\\pm0.2} M_{\\odot}$. Based on this combined analysis, we determine\nthat the absorber is consistent with being an inflowing filament. The $z_{\\rm\nabs}$=1.393 Mg\\,II system traces dense CGM gas clumps varying in strength over\n$\\lesssim$ 2 kpc physical scales. Our findings suggest that this absorber is\nlikely related to an outflowing clump. Our joint approach combining\n3D-spectroscopy observations of lensed systems and simulations with extreme\nresolution in the CGM put new constraints on the clumpiness of cold CGM gas, a\nkey diagnostic of the baryon cycle." }, { "anchor": "GMRT observations of a first sample of Extremely Inverted Spectrum\n Extragalactic Radio Sources (EISERS) candidates in the Northern sky: We present an extension of our search for Extremely Inverted Spectrum\nExtragalactic Radio Sources (EISERS) to the northern celestial hemisphere. With\nan inverted radio spectrum of slope $\\alpha$ > +2.5, these rare sources would\neither require a non-standard particle acceleration mechanism (in the framework\nof synchrotron self-absorption hypothesis), or a severe free-free absorption\nwhich attenuates practically all of their synchrotron radiation at metre\nwavelengths. By applying a sequence of selection filters, a list of 15 EISERS\ncandidates is extracted out by comparing two large-sky radio surveys, WENSS\n(325 MHz) and TGSS-ADR1 (150 MHz), which overlap across 1.03$\\pi$ steradian of\nthe sky. Here we report quasi-simultaneous GMRT observations of these 15 EISERS\ncandidates at 150 MHz and 325 MHz, in an attempt to accurately define their\nspectra below the turnover frequency. Out of the 15 candidates observed, two\nare confirmed as EISERS, since the slope of the inverted spectrum between these\ntwo frequencies is found to be significantly larger than the critical value\n$\\alpha_c$ = +2.5: the theoretical limit for the standard case of synchrotron\nself-absorption (SSA). For another 3 sources, the spectral slope is close to,\nor just above the critical value $\\alpha_c$. Nine of the sources have GPS type\nradio spectra. The parsec-scale radio structural information available for the\nsample is also summarised.", "positive": "On the magnetic field properties of protostellar envelopes in Orion: We present 870 um polarimetric observations toward 61 protostars in the Orion\nmolecular clouds, with ~400 au (1\") resolution using the Atacama Large\nMillimeter/submillimeter Array. We successfully detect dust polarization and\noutflow emission in 56 protostars, in 16 of them the polarization is likely\nproduced by self-scattering. Self-scattering signatures are seen in several\nClass 0 sources, suggesting that grain growth appears to be significant in\ndisks at earlier protostellar phases. For the rest of the protostars, the dust\npolarization traces the magnetic field, whose morphology can be approximately\nclassified into three categories: standard-hourglass, rotated-hourglass (with\nits axis perpendicular to outflow), and spiral-like morphology. 40.0% (+-3.0%)\nof the protostars exhibit a mean magnetic field direction approximately\nperpendicular to the outflow on several 100--1000 au scales. However, in the\nremaining sample, this relative orientation appears to be random, probably due\nto the complex set of morphologies observed. Furthermore, we classify the\nprotostars into three types based on the C17O (3--2) velocity envelope's\ngradient: perpendicular to outflow, non-perpendicular to outflow, and\nunresolved gradient (<1.0~km/s/arcsec). In protostars with a velocity gradient\nperpendicular to outflow, the magnetic field lines are preferentially\nperpendicular to outflow, most of them exhibit a rotated hourglass morphology,\nsuggesting that the magnetic field has been overwhelmed by gravity and angular\nmomentum. Spiral-like magnetic fields are associated with envelopes having\nlarge velocity gradients, indicating that the rotation motions are strong\nenough to twist the field lines. All of the protostars with a\nstandard-hourglass field morphology show no significant velocity gradient due\nto the strong magnetic braking." }, { "anchor": "Active Galactic Nuclei: This work represents the final year project for BSc Physics with Astrophysics\ndegree and it mainly focuses on empirical investigation of the photometry of\nquasars in the Sloan Digital Sky Survey (SDSS) and the UK Infrared Telescope\n(UKIRT) Infrared Sky Survey (UKIDSS) systems. The studies include 5730 quasars\nmatched from both surveys and examine UV/optical/near-IR properties of the\npopulation. The sample covers the redshift and absolute magnitude ranges 0.01 <\nz < 3 and -29.3 < M i < -13.8 and 17 per cent of the SDSS quasars have matching\nsuccess to the UKIDSS data. The combination of SDSS ugriz with the JHK near-IR\nphotometry from UKIDSS over large areas of the sky has enormous potential for\nadvancing our understanding of quasar population, keeping in mind that these\nsurveys have not reached their terminations.", "positive": "NIKA2 observations of starless cores in Taurus and Perseus: Dusty starless cores play an important role in regulating the initial phases\nof the formation of stars and planets. In their interiors, dust grains\ncoagulate and ice mantles form, thereby changing the millimeter emissivities\nand hence the ability to cool. We mapped four regions with more than a dozen\ncores in the nearby Galactic filaments of Taurus and Perseus using the NIKA2\ncamera at the IRAM 30-meter telescope. Combining the 1mm to 2mm flux ratio maps\nwith dust temperature maps from Herschel allowed to create maps of the dust\nemissivity index $\\beta_{1,2}$ at resolutions of 2430 and 5600 a.u. in Taurus\nand Perseus, respectively. Here, we study the variation with total column\ndensities and environment. $\\beta_{1,2}$ values at the core centers\n($A_V=12-19$mag) vary significantly between $\\sim1.1$ and $2.3$. Several cores\nshow a strong rise of $\\beta_{1,2}$ from the outskirts at $\\sim4$mag to the\npeaks of optical extinctions, consistent with the predictions of grain models\nand the gradual build-up of ice mantles on coagulated grains in the dense\ninteriors of starless cores." }, { "anchor": "Fragmentation in the Massive Star-Forming Region IRAS 19410+2336: The Core Mass Functions (CMFs) of low-mass star-forming regions are found to\nresemble the shape of the Initial Mass Function (IMF). A similar result is\nobserved for the dust clumps in high-mass star forming regions, although at\nspatial scales of clusters that do not resolve the substructure found in them.\nThe region IRAS 19410+2336 is one exception, having been observed at spatial\nscales on the order of ~2500AU, resolving the clump substructure into\nindividual cores.\n We mapped that region with the PdBI in the 1.4mm and 3mm continuum and\nseveral transitions of H2CO and CH3CN. The H2CO transitions were also observed\nwith the IRAM 30m Telescope. We detected 26 continuum sources at 1.4mm with a\nspatial resolution down to ~2200 AU, distributed in two protoclusters. With the\nlines emission we derived the temperature structure of the region, ranging from\n35 to 90K. With them we calculated the core masses of the detected sources,\nranging from ~0.7 to ~8 M_sun. These masses were strongly (~90%) affected by\nthe interferometer spatial filtering. Considering only the detected dense cores\nwe derived a CMF with a power-law index b=-2.3+-0.2. We resolve the Jeans\nlength of the protoclusters by one order of magnitude, and only find little\nvelocity dispersion between the different subsources.\n Since we cannot unambiguously differentiate protostellar and prestellar\ncores, the derived CMF is not prestellar. Also, because of the large missing\nflux, we cannot establish a firm link between the CMF and the IMF. This implies\nthat future high-mass CMF studies will need to complement the interferometer\ncontinuum data with the short spacing data, a task suitable for ALMA. We note\nthat the method of extracting temperatures using H2CO lines becomes less\napplicable when reaching the dense core scales of the interferometric\nobservations because most of the H2CO appears to originate in the envelope\nstructure.", "positive": "Radio Imaging of the NGC 1333 IRAS 4B Region: The NGC 1333 IRAS 4B region was observed in the 6.9 mm and 1.3 cm continuum\nwith an angular resolution of about 0.4 arcseconds. IRAS 4BI was detected in\nboth bands, and BII was detected in the 6.9 mm continuum only. The 1.3 cm\nsource of BI seems to be a disk-like flattened structure with a size of about\n50 AU. IRAS 4BI does not show any sign of multiplicity. Examinations of\narchival infrared images show that the dominating emission feature in this\nregion is a bright peak in the southern outflow driven by BI, corresponding to\nthe molecular hydrogen emission source HL 9a. Both BI and BII are undetectable\nin the mid-IR bands. The upper limit on the far-IR flux of IRAS 4BII suggests\nthat it may be a very low luminosity young stellar object." }, { "anchor": "AGN's Deadness Over Cosmic Time: UVJ Diagrams of X-Ray-Selected AGN: Active Galactic Nuclei (AGN) are intensely accreting supermassive black holes\nat the centers of massive galaxies. Though these objects occupy little spatial\nextent of the galaxy itself, they are thought to have far reaching affects,\nimpacting the galaxy's star formation, and possibly it's lifespan until it\nbecomes 'red and dead'. Typical galaxies demonstrate that, over cosmic time,\nthey tend to separate into a bimodal distribution of 'red and dead' or blue and\nstar forming. We examine whether active galaxies evolve over cosmic time in a\nsimilar way, and whether this can reveal anything about the complexities of the\nrelationship between an AGN and the host galaxy. We use the Stripe82X survey to\nidentify 3940 X-ray AGN spanning z=0-2.5, and we measure the rest-frame UVJ\ncolors of each galaxy. We classify AGN as star-forming or quiescent based on\ntheir location in a UVJ color diagram. We find that there is not a clear\nbimodal distribution between AGN in star forming and quiescent galaxies.\nFurthermore, the most luminous X-ray sources tend to lie in the star forming\nregion, which may indicate a correlation between central engine activity and\nincreased rates of star formation.", "positive": "Understanding the spatial variation of \\ion{Mg}{II} and ionizing photon\n escape in a local LyC leaker: Ionizing photons must have escaped from high-redshift galaxies, but the\nneutral high-redshift intergalactic medium makes it unlikely to directly detect\nthese photons during the Epoch of Reionization. Indirect methods of studying\nionizing photon escape fractions present a way to infer how the first galaxies\nmay have reionized the universe. Here, we use HET/LRS2 observations of\nJ0919+4906, a confirmed z$\\approx$0.4 emitter of ionizing photons to achieve\nspatially resolved (12.5 kpc in diameter) spectroscopy of\n\\ion{Mg}{II}$\\lambda2796$, \\ion{Mg}{II}$\\lambda2803$,\n[\\ion{O}{II}]$\\lambda\\lambda3727,3729$ , [\\ion{Ne}{III}]$\\lambda3869$,\nH$\\gamma$, [\\ion{O}{III}]$\\lambda4363$, H$\\beta$, [\\ion{O}{III}]$\\lambda4959$,\n[\\ion{O}{III}]$\\lambda5007$, and H$\\alpha$. From these data we measure\n\\ion{Mg}{II} emission, which is a promising indirect tracer of ionizing\nphotons, along with nebular ionization and dust attenuation in multiple\nspatially-resolved apertures. We find that J0919+4906 has significant spatial\nvariation in its \\ion{Mg}{II} escape and thus ionizing photon escape fraction.\nCombining our observations with photoionization models, we find that the\nregions with the largest relative \\ion{Mg}{II} emission and \\ion{Mg}{II} escape\nfractions have the highest ionization and lowest dust attenuation. Some regions\nhave an escape fraction that matches that required by models to reionize the\nearly universe, while other regions do not. We observe a factor of 36 spatial\nvariation in the inferred LyC escape fraction, which is similar to recently\nobserved statistical samples of indirect tracers of ionizing photon escape\nfractions. These observations suggest that spatial variations in neutral gas\nproperties lead to large variations in the measured LyC escape fractions. Our\nresults suggest that single sightline observations may not trace the\nvolume-averaged escape fraction of ionizing photons." }, { "anchor": "Molecular Tracers of Turbulent Shocks in Giant Molecular Clouds: Giant molecular clouds contain supersonic turbulence and simulations of\nmagnetohydrodynamic turbulence show that these supersonic motions decay in\nroughly a crossing time, which is less than the estimated lifetimes of\nmolecular clouds. Such a situation requires a significant release of energy. We\nrun models of C-type shocks propagating into gas with densities around 10^3\ncm^(-3) at velocities of a few km / s, appropriate for the ambient conditions\ninside of a molecular cloud, to determine which species and transitions\ndominate the cooling and radiative energy release associated with shock cooling\nof turbulent molecular clouds. We find that these shocks dissipate their energy\nprimarily through CO rotational transitions and by compressing pre-existing\nmagnetic fields. We present model spectra for these shocks and by combining\nthese models with estimates for the rate of turbulent energy dissipation, we\nshow that shock emission should dominate over emission from unshocked gas for\nmid to high rotational transitions (J >5) of CO. We also find that the\nturbulent energy dissipation rate is roughly equivalent to the cosmic-ray\nheating rate and that the ambipolar diffusion heating rate may be significant,\nespecially in shocked gas.", "positive": "Molecular Gas Properties and CO-to-H2 Conversion Factors in the Central\n Kiloparsec of NGC 3351: The CO-to-H$_2$ conversion factor ($\\alpha_\\rm{CO}$) is critical to studying\nmolecular gas and star formation in galaxies. The value of $\\alpha_\\rm{CO}$ has\nbeen found to vary within and between galaxies, but the specific environmental\nconditions that cause these variations are not fully understood. Previous\nobservations on $\\sim$kpc scales revealed low values of $\\alpha_\\rm{CO}$ in the\ncenters of some barred spiral galaxies, including NGC 3351. We present new ALMA\nBand 3, 6, and 7 observations of $^{12}$CO, $^{13}$CO, and C$^{18}$O lines on\n100 pc scales in the inner $\\sim$2 kpc of NGC 3351. Using multi-line radiative\ntransfer modeling and a Bayesian likelihood analysis, we infer the H$_2$\ndensity, kinetic temperature, CO column density per line width, and CO\nisotopologue abundances on a pixel-by-pixel basis. Our modeling implies the\nexistence of a dominant gas component with a density of $2{-}3\\times10^3$\n$\\rm{cm^{-3}}$ in the central ${\\sim}$1 kpc and a high temperature of 30$-$60 K\nnear the nucleus and near the contact points that connect to the bar-driven\ninflows. Assuming a CO/H$_2$ abundance of $3\\times10^{-4}$, our analysis yields\n$\\alpha_\\rm{CO}{\\sim}0.5{-}2.0$ $\\rm{M_\\odot\\,(K~km~s^{-1}~pc^2)^{-1}}$ with a\ndecreasing trend with galactocentric radius in the central $\\sim$1 kpc. The\ninflows show a substantially lower $\\alpha_\\rm{CO} < 0.1$\n$\\rm{M_\\odot\\,(K~km~s^{-1}~pc^2)^{-1}}$, likely due to lower optical depths\ncaused by turbulence or shear in the inflows. Over the whole region, this gives\nan intensity-weighted $\\alpha_\\rm{CO}$ of ${\\sim}1.5$\n$\\rm{M_\\odot\\,(K~km~s^{-1}~pc^2)^{-1}}$, which is similar to previous dust\nmodeling based results at kpc scales. This suggests that low $\\alpha_\\rm{CO}$\non kpc scales in the centers of some barred galaxies may be due to the\ncontribution of low optical depth CO emission in bar-driven inflows." }, { "anchor": "A universal angular momentum profile for dark matter haloes: The angular momentum distribution in dark matter haloes and galaxies is a key\ningredient in understanding their formation. Especially, the internal\ndistribution of angular momenta is closely related to the formation of disk\ngalaxies. In this article, we use haloes identified from a high-resolution\nsimulation, the Bolshoi simulation, to study the spatial distribution of\nspecific angular momenta, $j(r,\\theta)$. We show that by stacking haloes with\nsimilar masses to increase the signal-to-noise ratio, the profile can be fitted\nas a simple function, $j(r,\\theta)=j_s \\sin^2(\\theta/\\theta_s)\n(r/r_s)^2/(1+r/r_s)^4 $, with three free parameters, $j_s, r_s$, and\n$\\theta_s$. Specifically, $j_s$ correlates with the halo mass $M_\\mathrm{vir}$\nas $j_s\\propto M_\\mathrm{vir}^{2/3}$, $r_s$ has a weak dependence on the halo\nmass as $r_s \\propto M_\\mathrm{vir}^{0.040}$, and $\\theta_s$ is independent of\n$M_\\mathrm{vir}$. This profile agrees with that from a rigid shell model,\nthough its origin is unclear. Our universal specific angular momentum profile\n$j(r,\\theta)$ is useful in modelling haloes' angular momenta. Furthermore, by\nusing an empirical stellar mass - halo mass relation, we can infer the averaged\nangular momentum distribution of a dark matter halo. The specific angular\nmomentum - stellar mass relation within a halo computed from our profile is\nshown to share a similar shape as that from the observed disk galaxies.", "positive": "The Panchromatic Hubble Andromeda Treasury XV. The BEAST: Bayesian\n Extinction and Stellar Tool: We present the Bayesian Extinction And Stellar Tool (BEAST), a probabilistic\napproach to modeling the dust extinguished photometric spectral energy\ndistribution of an individual star while accounting for observational\nuncertainties common to large resolved star surveys. Given a set of photometric\nmeasurements and an observational uncertainty model, the BEAST infers the\nphysical properties of the stellar source using stellar evolution and\natmosphere models and constrains the line of sight extinction using a newly\ndeveloped mixture model that encompasses the full range of dust extinction\ncurves seen in the Local Group. The BEAST is specifically formulated for use\nwith large multi-band surveys of resolved stellar populations. Our approach\naccounts for measurement uncertainties and any covariance between them due to\nstellar crowding (both systematic biases and uncertainties in the bias) and\nabsolute flux calibration, thereby incorporating the full information content\nof the measurement. We illustrate the accuracy and precision possible with the\nBEAST using data from the Panchromatic Hubble Andromeda Treasury. While the\nBEAST has been developed for this survey, it can be easily applied to similar\nexisting and planned resolved star surveys." }, { "anchor": "Faint emission lines in planetary nebulae with a [WC] nucleus: We present first results from the analysis of a sample of 14 planetary\nnebulae with [WC] nucleus with detected faint carbon and oxygen recombination\nlines (RLs). The results are based on deep echelle spectra obtained with MIKE\non the 6.5 m Magellan-Clay telescope in Chile.", "positive": "Modelling line emission of deuterated H_3^+ from prestellar cores: Context: The depletion of heavy elements in cold cores of interstellar\nmolecular clouds can lead to a situation where deuterated forms of H_3^+ are\nthe most useful spectroscopic probes of the physical conditions.\n Aims: The aim is to predict the observability of the rotational lines of\nH_2D^+ and D_2H^+ from prestellar cores.\n Methods: Recently derived rate coefficients for the H_3^+ + H_2 isotopic\nsystem were applied to the \"complete depletion\" reaction scheme to calculate\nabundance profiles in hydrostatic core models. The ground-state lines of\nH_2D^+(o) (372 GHz) and D_2H^+(p) (692 GHz) arising from these cores were\nsimulated. The excitation of the rotational levels of these molecules was\napproximated by using the state-to-state coefficients for collisions with H_2.\nWe also predicted line profiles from cores with a power-law density\ndistribution advocated in some previous studies.\n Results: The new rate coefficients introduce some changes to the complete\ndepletion model, but do not alter the general tendencies. One of the\nmodifications with respect to the previous results is the increase of the D_3^+\nabundance at the cost of other isotopologues. Furthermore, the present model\npredicts a lower H_2D^+ (o/p) ratio, and a slightly higher D_2H^+ (p/o) ratio\nin very cold, dense cores, as compared with previous modelling results. These\nnuclear spin ratios affect the detectability of the submm lines of H_2D^+(o)\nand D_2H^+(p). The previously detected H_2D^+ and D_2H^+ lines towards the core\nI16293E, and the H_2D^+ line observed towards Oph D can be reproduced using the\npresent excitation model and the physical models suggested in the original\npapers." }, { "anchor": "The Impact of Far-Infrared/Sub-Millimeter Data on the Star Formation\n Rates of Massive Dusty Galaxies at Cosmic Noon: We explore how the star formation rate (SFR), stellar mass, and other\nproperties of massive dusty galaxies at cosmic noon are impacted when\nfar-infrared (FIR)/sub-millimeter data are added to datasets containing only\nultraviolet (UV) to near-infrared (NIR) data. For a sample of 92 massive\n(stellar mass $> 4{\\times}10^{10}$ M$_{\\odot}$) dusty galaxies at\n$z\\,{\\sim}\\,1.5$ to 3.0 (corresponding to ${\\sim}25$% of cosmic history), we\nfit the spectral energy distributions (SEDs) based on DECam UV-to-optical data,\nVICS82, NEWFIRM, and Spitzer-IRAC NIR data, and Herschel-SPIRE\nFIR/sub-millimeter data using the Bayesian Analysis of Galaxies for Physical\nInference and Parameter Estimation (BAGPIPES) SED-fitting code. We assume a\ndelayed tau star formation history with a log$_{10}$ prior on tau and derive\nthe posterior distributions of stellar mass, SFR, extinction, and specific SFR.\nWe find that adding FIR/sub-millimeter data leads to SFR estimates that can be\nboth significantly higher or lower (typically by up to a factor of 10) than\nestimates based on UV-to-NIR data alone, depending on the type of galaxies\ninvolved. We find that the changes in SFR scale with changes in extinction.\nThese results highlight the importance of including FIR/sub-millimeter data in\norder to accurately derive the SFRs of massive dusty galaxies at\n$z\\,{\\sim}\\,2$.", "positive": "An Analysis of HCN Observations of The Galactic Centre's Circumnuclear\n Disk: The Circumnuclear Disk (CND) is a torus of dust and moleular gas rotating\nabout the galactic centre and extends from 1.6 to 7pc from the central massive\nblack hole SgrA*. Large Velocity Gradient modelling of selected transitions of\nHCN rotational collisions with molecular hydrogen is used to infer Hydrogen\ndensity and HCN opacities. The analysis concludes that the predicted hydrogen\nnumber density of CND clumps is about 10^6 which is insufficiently dense to\nwithstand the tidal shear forces generated by SgrA* and the stellar group in\nthe cavity between the galactic centre and the CND." }, { "anchor": "Gaia Universe Model Snapshot : A statistical analysis of the expected\n contents of the Gaia catalogue: Context. This study has been developed in the framework of the computational\nsimulations executed for the preparation of the ESA Gaia astrometric mission.\nAims. We focus on describing the objects and characteristics that Gaia will\npotentially observe without taking into consideration instrumental effects\n(detection efficiency, observing errors). Methods. The theoretical Universe\nModel prepared for the Gaia simulation has been statistically analyzed at a\ngiven time. Ingredients of the model are described, giving most attention to\nthe stellar content, the double and multiple stars, and variability. Results.\nIn this simulation the errors have not been included yet. Hence we estimate the\nnumber of objects and their theoretical photometric, astrometric and\nspectroscopic characteristics in the case that they are perfectly detected. We\nshow that Gaia will be able to potentially observe 1.1 billion of stars (single\nor part of multiple star systems) of which about 2% are variable stars, 3% have\none or two exoplanets. At the extragalactic level, observations will be\npotentially composed by several millions of galaxies, half million to 1 million\nof quasars and about 50,000 supernovas that will occur during the 5 years of\nmission. The simulated catalogue will be made publicly available by the DPAC on\nthe Gaia portal of the ESA web site http://www.rssd.esa.int/gaia/.", "positive": "The Galactic Center: Not an Active Galactic Nucleus: We present 10um-35um Spitzer spectra of the interstellar medium in the\nCentral Molecular Zone (CMZ), the central 210 pc x 60 pc of the Galactic center\n(GC). We present maps of the CMZ in ionic and H2 emission, covering a more\nextensive area than earlier spectroscopic surveys in this region. The radial\nvelocities and intensities of ionic lines and H2 suggest that most of the H2\n0-0 S(0) emission comes from gas along the line-of-sight, as found by previous\nwork. We compare diagnostic line ratios measured in the Spitzer Infrared Nearby\nGalaxies Survey (SINGS) to our data. Previous work shows that forbidden line\nratios can distinguish star-forming galaxies from LINERs and AGNs. Our GC line\nratios agree with star-forming galaxies and not with LINERs or AGNs." }, { "anchor": "High-resolution ALMA Observations of SDP.81. II. Molecular Clump\n Properties of a Lensed Submillimeter Galaxy at z=3.042: We present spatially-resolved properties of molecular gas and dust in a\ngravitationally-lensed submillimeter galaxy H-ATLAS J090311.6+003906 (SDP.81)\nat $z=3.042$ revealed by the Atacama Large Millimeter/submillimeter Array\n(ALMA). We identified 14 molecular clumps in the CO(5-4) line data, all with a\nspatial scale of $\\sim$50-300 pc in the source plane. The surface density of\nmolecular gas ($\\Sigma_{\\rm H_2}$) and star-formation rate ($\\Sigma_{\\rm SFR}$)\nof the clumps are more than three orders of magnitude higher than those found\nin local spiral galaxies. The clumps are placed in the `burst' sequence in the\n$\\Sigma_{\\rm H_2}$-$\\Sigma_{\\rm SFR}$ plane, suggesting that $z \\sim 3$\nmolecular clumps follow the star-formation law derived for local starburst\ngalaxies. With our gravitational lens model, the positions in the source plane\nare derived for the molecular clumps, dust clumps, and stellar components\nidentified in the {\\sl Hubble Space Telescope} image. The molecular and dust\nclumps coexist in a similar region over $\\sim$2 kpc, while the stellar\ncomponents are offset at most by $\\sim$5 kpc. The molecular clumps have a\nsystematic velocity gradient in the north-south direction, which may indicate a\nrotating gas disk. One possible scenario is that the components of molecular\ngas, dust, and stars are distributed in a several-kpc scale rotating disk, and\nthe stellar emission is heavily obscured by dust in the central star-forming\nregion. Alternatively, SDP.81 can be explained by a merging system, where dusty\nstarbursts occur in the region where the two galaxies collide, surrounded by\ntidal features traced in the stellar components.", "positive": "The universal power spectrum of Quasars in optical wavelengths: Break\n timescale scales directly with both black hole mass and accretion rate: Aims: Establish the dependence of variability properties, such as\ncharacteristic timescales and variability amplitude, on basic quasar parameters\nsuch as black hole mass and accretion rate, controlling for the rest-frame\nwavelength of emission. Methods: Using large catalogs of quasars, we selected\nthe g-band light curves for 4770 objects from the Zwicky Transient Facility\narchive. All selected objects fall into a narrow redshift bin, $0.60.1 Msun. The disk masses for our sample are significantly\nhigher than for samples of more evolved Class II objects. Thus, Class I disk\nmasses probably provide a more accurate estimate of the initial mass budget for\nstar and planet formation. However, the disk masses determined here are lower\nthan required by theories of giant planet formation. The masses also appear too\nlow for gravitational instability, which could lead to high mass accretion\nrates. Even in these Class I disks, substantial particle growth may have hidden\nmuch of the disk mass in hard-to-see larger bodies." }, { "anchor": "A Robust Study of High-Redshift Galaxies: Unsupervised Machine Learning\n for Characterising morphology with JWST up to z ~ 8: Galaxy morphologies provide valuable insights into their formation processes,\ntracing the spatial distribution of ongoing star formation and encoding\nsignatures of dynamical interactions. While such information has been\nextensively investigated at low redshift, it is crucial to develop a robust\nsystem for characterising galaxy morphologies at earlier cosmic epochs. Relying\nsolely on the nomenclature established for low-redshift galaxies risks\nintroducing biases that hinder our understanding of this new regime. In this\npaper, we employ variational auto-encoders to perform feature extraction on\ngalaxies at z $>$ 2 using JWST/NIRCam data. Our sample comprises 6869 galaxies\nat z $>$ 2, including 255 galaxies z $>$ 5, which have been detected in both\nthe CANDELS/HST fields and CEERS/JWST, ensuring reliable measurements of\nredshift, mass, and star formation rates. To address potential biases, we\neliminate galaxy orientation and background sources prior to encoding the\ngalaxy features, thereby constructing a physically meaningful feature space. We\nidentify 11 distinct morphological classes that exhibit clear separation in\nvarious structural parameters, such as CAS-$M_{20}$, S\\'ersic indices, specific\nstar formation rates, and axis ratios. We observe a decline in the presence of\nspheroidal-type galaxies with increasing redshift, indicating a dominance of\ndisk-like galaxies in the early universe. We demonstrate that conventional\nvisual classification systems are inadequate for high-redshift morphology\nclassification and advocate the need for a more detailed and refined\nclassification scheme. Leveraging machine-extracted features, we propose a\nsolution to this challenge and illustrate how our extracted clusters align with\nmeasured parameters, offering greater physical relevance compared to\ntraditional methods.", "positive": "Chemical pre-processing of cluster galaxies over the past 10 billion\n years in the IllustrisTNG simulations: We use the IllustrisTNG simulations to investigate the evolution of the\nmass-metallicity relation (MZR) for star-forming cluster galaxies as a function\nof the formation history of their cluster host. The simulations predict an\nenhancement in the gas-phase metallicities of star-forming cluster galaxies\n(10^9< M_star<10^10 M_sun) at z<1.0 in comparisons to field galaxies. This is\nqualitatively consistent with observations. We find that the metallicity\nenhancement of cluster galaxies appears prior to their infall into the central\ncluster potential, indicating for the first time a systematic \"chemical\npre-processing\" signature for {\\it infalling} cluster galaxies. Namely,\ngalaxies which will fall into a cluster by z=0 show a ~0.05 dex enhancement in\nthe MZR compared to field galaxies at z<0.5. Based on the inflow rate of gas\ninto cluster galaxies and its metallicity, we identify that the accretion of\npre-enriched gas is the key driver of the chemical evolution of such galaxies,\nparticularly in the stellar mass range (10^9< M_star<10^10 M_sun). We see\nsignatures of an environmental dependence of the ambient/inflowing gas\nmetallicity which extends well outside the nominal virial radius of clusters.\nOur results motivate future observations looking for pre-enrichment signatures\nin dense environments." }, { "anchor": "The 2200 A bump and the UV extinction curve: The 2200 A bump is a major figure of interstellar extinction. Extinction\ncurves with no bump however exist and are, with no exception, linear from the\nnear-infrared down to 2500 A at least, often over all the visible-UV spectrum.\nThe duality linear versus bump-like extinction curves can be used to\nre-investigate the relationship between the bump and the continuum of\ninterstellar extinction, and answer questions as why do we observe two\ndifferent kinds of extinction (linear or with a bump) in interstellar clouds?\nHow are they related? How does the existence of two different extinction laws\nfits with the requirement that extinction curves depend exclusively on the\nreddening E(B-V) and on a single additional parameter? What is this free\nparameter?\n It will be found that (1) interstellar dust models, which suppose the\nexistence of three different types of particles, each contributing to the\nextinction in a specific wavelength range, fail to account for the\nobservations; (2) the 2200 A bump is very unlikely to be absorption by some yet\nunidentified molecule; (3) the true law of interstellar extinction must be\nlinear from the visible to the far-UV, and is the same for all directions,\nincluding other galaxies.\n In extinction curves with a bump the excess of starlight (or the lack of\nextinction) observed at wavelengths less than lambda=4000 A is due to a large\ncontribution of light scattered by hydrogen on the line of sight. Although\ncounter-intuitive this contribution is predicted by theory. The free parameter\nof interstellar extinction is related to distances between the observer, the\ncloud on the line of sight, and the star behind it (the parameter is likely to\nbe the ratio of the distances from the cloud to the star and to the observer).\nThe continuum of the extinction curve or the bump contain no information\nconcerning the chemical composition of interstellar cloud.", "positive": "Young Star Clusters Dominate the Production of Detached Black Hole-Star\n Binaries: The recent discovery of two detached black hole-star (BH-star) binaries from\nGaia's third data release has sparkled interest in understanding the formation\nmechanisms of these systems. We investigate the formation of these systems by\ndynamical processes in young open star clusters (SCs) and via isolated binary\n(IB) evolution, using a combination of direct $N$-body models and population\nsynthesis simulations. By comparing dynamical and isolated systems created\nusing the same model of binary stellar evolution, we find that dynamical\nformation in SCs is nearly 40 times as efficient per unit of star formation at\nproducing BH-star binaries compared to IB evolution. We expand this analysis to\nthe full Milky Way (MW) using a FIRE-2 hydrodynamical simulation of a MW-mass\ngalaxy. Even assuming that only $10\\%$ of star formation produces SCs with\nmasses $> 1000\\,\\mathrm{M_{\\odot}}$, we find that the MW contains $\\sim 2\n\\times 10^5$ BH-star systems, with approximately 4 out of every 5 systems being\nformed dynamically. Many of these dynamically-formed systems have larger\norbital periods, eccentricities, and black hole masses than their isolated\ncounterparts. For binaries older than 100 Myr, we show that any detectable\nsystem with $e\\gtrsim0.5$ or $M_{\\rm BH}\\gtrsim 10\\,\\mathrm{M_{\\odot}}$ can\nonly be formed through dynamical processes. Our MW model predicts between 61\nand 210 such detections from the complete DR4 Gaia catalog, with the majority\nof systems being dynamically formed in massive and metal-rich SCs. Finally, we\ncompare our populations to the recently discovered Gaia BH1 and Gaia BH2, and\nconclude that the dynamical scenario is the most favorable formation pathway\nfor both systems." }, { "anchor": "Observational signatures of massive black hole formation in the early\n universe: Space telescope observations of massive black holes during their formation\nmay be key to understanding the origin of supermassive black holes and\nhigh-redshift quasars. To create diagnostics for their detection and\nconfirmation, we study a simulation of a nascent massive, so-called\ndirect-collapse, black hole that induces a wave of nearby massive metal-free\nstar formation, unique to this seeding scenario and to very high redshifts.\nHere we describe a series of distinct colors and emission line strengths,\ndependent on the relative strength of star formation and black hole accretion.\nWe predict that the forthcoming James Webb Space Telescope might be able to\ndetect and distinguish a young galaxy that hosts a direct-collapse black hole\nin this configuration at redshift 15 with as little as a 20,000-second total\nexposure time across four filters, critical for constraining supermassive black\nhole seeding mechanisms and early growth rates. We also find that a massive\nseed black hole produces strong, H$_2$-dissociating Lyman-Werner radiation.", "positive": "Herschel-HIFI observations of high-J CO and isotopologues in\n star-forming regions: from low- to high-mass: Context; Our understanding of the star formation process has traditionally\nbeen confined to certain mass or luminosity boundaries because most studies\nfocus only on low-, intermediate- or high-mass star-forming regions. As part of\nthe \"Water In Star-forming regions with Herschel\" (WISH) key program, water and\nother important molecules, such as CO and OH, have been observed in 51 embedded\nyoung stellar objects (YSOs). The studied sample covers a range of luminosities\nfrom <1 to >10^5 L_sol. Aims; We analyse the CO line emission towards a large\nsample of protostars in terms of both line intensities and profiles. Methods;\nHerschel-HIFI spectra of the 12CO 10-9, 13CO 10-9 and C18O 5-4, 9-8 and 10-9\nlines are analysed for a sample of 51 YSOs. In addition, JCMT spectra of 12CO\n3-2 and C18O 3-2 extend this analysis to cooler gas components. Results; All\nobserved CO and isotopologue spectra show a strong linear correlation between\nthe logarithms of the line and bolometric luminosities across six orders of\nmagnitude on both axes. This suggests that the high-J CO lines primarily trace\nthe amount of dense gas associated with YSOs. This relation can be extended to\nlarger (extragalactic) scales. The majority of the detected 12CO line profiles\ncan be decomposed into a broad and a narrow Gaussian component, while the C18O\nspectra are mainly fitted with a single Gaussian. A broadening of the line\nprofile is also observed from pre-stellar cores to embedded protostars, which\nis due mostly to non-thermal motions (turbulence/infall). The widths of the\nbroad 12CO 3-2 and 10-9 velocity components correlate with those of the narrow\nC18O 9-8 profiles, suggesting that the entrained outflowing gas and envelope\nmotions are related independent of the mass of the protostar. These results\nindicate that physical processes in protostellar envelopes have similar\ncharacteristics across the studied luminosity range." }, { "anchor": "Enhanced Destruction of Cluster Satellites by Major Mergers: Using a set of clusters in dark matter only cosmological simulations, we\nstudy the consequences of merging of clusters and groups of galaxies (with mass\nratio larger than 5:1) to investigate the tidal impact of mergers on the\nsatellite halos. We compare our results to a control sample of clusters that\nhave had no major mergers over the same time period. Clusters that undergo\nmajor mergers are found to have a significant enhancement in destruction of\ntheir subhalos of ~10-30%, depending on how major the merger is. Those with\nmass ratios less than 7:1 showed no significant enhancement. The number of\ndestroyed subhalos are measured for the cluster members that were inside the\nvirial radius of clusters before the merger begins. This means preprocessed\ngalaxies brought in by the merger are deliberately excluded, allowing us to\nclearly see the enhanced destruction purely as a result of the distorted and\ndisturbed tidal field of the cluster during the merger. We also consider\nsecondary parameters affecting the destruction of those satellites but find\nthat the major mergers are the dominant factor. These results highlight how\nmajor mergers can significantly impact the cluster population, with likely\nconsequences for the formation of intracluster light, and enhancement of tidal\nfeatures in the remaining satellites.", "positive": "Far-ultraviolet study of the local supershell GSH 006-15+7: We have analyzed the archival data of FUV observations for the region of GSH\n006-15+7, a large shell-like structure discovered by Moss et al. (2012) from\nthe H I velocity maps. FUV emission is seen to be enhanced in the lower\nsupershell region. The FUV emission is considered to come mainly from the\nscattering of interstellar photons by dust grains. A corresponding Monte Carlo\nsimulation indicates that the distance to the supershell is 1300 +- 800 pc,\nwhich is similar to the previous estimation of 1500 +- 500 pc based on\nkinematic considerations. The spectrum at lower Galactic latitudes of the\nsupershell exhibits molecular hydrogen fluorescence lines; a simulation model\nfor this candidate photodissociation region (PDR) yields an H_2 column density\nof N(H_2) = 10^{18.0-20.0} cm^{-2} with a rather high total hydrogen density of\nn_H ~ 30 cm^{-3}." }, { "anchor": "Mapping optically variable quasars towards the galactic plane: We present preliminary results of the CIDA Equatorial Variability Survey\n(CEVS), looking for quasar (hereafter QSO) candidates near the Galactic plane.\nThe CEVS contains photometric data from extended and adjacent regions of the\nMilky Way disk ($\\sim$ 500 sq. deg.). In this work 2.5 square degrees with\nmoderately high temporal sampling in the CEVS were analyzed. The selection of\nQSO candidates was based on the study of intrinsic optical photometric\nvariability of 14,719 light curves. We studied samples defined by cuts in the\nvariability index (Vindex $>$ 66.5), periodicity index (Q $>$ 2), and the\ndistribution of these sources in the plane (AT , ${\\gamma}$), using a slight\nmodification of the first-order of the structure function for the temporal\nsampling of the survey. Finally, 288 sources were selected as QSO candidates.\nThe results shown in this work are a first attempt to develop a robust method\nto detect QSO towards the Galactic plane in the era of massive surveys such as\nVISTA and Gaia.", "positive": "The oldest and most metal poor stars in the APOSTLE Local Group\n simulations: We examine the spatial distribution of the oldest and most metal poor stellar\npopulations of Milky Way-sized galaxies using the APOSTLE cosmological\nhydrodynamical simulations of the Local Group. In agreement with earlier work,\nwe find strong radial gradients in the fraction of the oldest (tform < 0.8 Gyr)\nand most metal poor ([Fe/H]< -2.5) stars, both of which increase outwards. The\nmost metal poor stars form over an extended period of time; half of them form\nafter z = 5.3, and the last 10% after z = 2.8. The age of the metal poor\nstellar population also shows significant variation with environment; a high\nfraction of them are old in the galaxy's central regions and an even higher\nfraction in some individual dwarf galaxies, with substantial scatter from dwarf\nto dwarf. Overall, over half of the stars that belong to both the oldest and\nmost metal-poor population are found outside the solar circle. Somewhat\ncounter-intuitively, we find that dwarf galaxies with a large fraction of metal\npoor stars that are very old are systems where metal poor stars are relatively\nrare, but where a substantial old population is present. Our results provide\nguidance for interpreting the results of surveys designed to hunt for the\nearliest and most pristine stellar component of our Milky Way." }, { "anchor": "Uncovering Multiple Populations in NGC 7099 (M 30) using Washington\n Photometry: Over the last decade, the classical definition of Globular Clusters (GCs) as\nsimple stellar populations was revolutionized due to the discovery of \"Multiple\nPopulations\" (MPs). However, our knowledge of this phenomenon and its\ncharacteristics is still lacking greatly observationally, and there is\ncurrently no scenario that adequately explains its origin. It is therefore\nimportant to study as many GCs as possible to characterize whether or not they\nhave MPs, and determine their detailed behavior to enlighten formation\nscenarios, using a wide range of techniques. The Washington photometric system\nhas proved to be useful to find MPs thanks mainly to the UV-sensitivity and\nhigh efficiency of the C filter. We search for MPs in the Galactic GC NGC 7099\n(M30), the second GC being searched for MPs using this system. We obtained\nphotometric data using the Swope 1m telescope at Las Campanas Observatory, as\nwell as the 4m SOAR facility. Our reduction procedure included addstar\nexperiments to properly assess photometric errors. We find a clear signal of\nMPs based on an intrinsically wide color spread on the RGB, in particular due\nto a relatively small fraction of stars significantly bluer than the main RGB\nlocus. These stars should correspond to so-called first generation stars, which\nwe estimate to be roughly 15\\% of the total. However, we find these\nfirst-generation stars to be more spatially concentrated than their second\ngeneration counterparts, which is the opposite to the general trend found in\nother clusters. We briefly discuss possible explanations for this phenomenon.", "positive": "Characterizing the radial oxygen abundance distribution in disk galaxies: We examine the possible dependence of the radial oxygen abundance\ndistribution on non-axisymmetrical structures (bar/spirals) and other\nmacroscopic parameters such as the mass, the optical radius R25, the color g-r,\nand the surface brightness of the galaxy. A sample of disk galaxies from the\nCALIFA DR3 is considered. We adopted the Fourier amplitude A2 of the surface\nbrightness as a quantitative characteristic of the strength of non-axisymmetric\nstructures in a galactic disk, in addition to the commonly used morphologic\ndivision for A, AB, and B types based on the Hubble classification. To\ndistinguish changes in local oxygen abundance caused by the non-axisymmetrical\nstructures, the multiparametric mass--metallicity relation was constructed as a\nfunction of parameters such as the bar/spiral pattern strength, the disk size,\ncolor index g-r in the SDSS bands, and central surface brightness of the disk.\nThe gas-phase oxygen abundance gradient is determined by using the R\ncalibration. We find that there is no significant impact of the\nnon-axisymmetric structures such as a bar and/or spiral patterns on the local\noxygen abundance and radial oxygen abundance gradient of disk galaxies.\nGalaxies with higher mass, however, exhibit flatter oxygen abundance gradients\nin units of dex/kpc, but this effect is significantly less prominent for the\noxygen abundance gradients in units of dex/R25 and almost disappears when the\ninner parts are avoided. We show that the oxygen abundance in the central part\nof the galaxy depends neither on the optical radius R25 nor on the color g-r or\nthe surface brightness of the galaxy. Instead, outside the central part of the\ngalaxy, the oxygen abundance increases with g-r value and central surface\nbrightness of the disk." }, { "anchor": "The Lockman Hole project: LOFAR observations and spectral index\n properties of low-frequency radio sources: The Lockman Hole is a well-studied extragalactic field with extensive\nmulti-band ancillary data covering a wide range in frequency, essential for\ncharacterising the physical and evolutionary properties of the various source\npopulations detected in deep radio fields (mainly star-forming galaxies and\nAGNs). In this paper we present new 150-MHz observations carried out with the\nLOw Frequency ARray (LOFAR), allowing us to explore a new spectral window for\nthe faint radio source population. This 150-MHz image covers an area of 34.7\nsquare degrees with a resolution of 18.6$\\times$14.7 arcsec and reaches an rms\nof 160 $\\mu$Jy beam$^{-1}$ at the centre of the field.\n As expected for a low-frequency selected sample, the vast majority of sources\nexhibit steep spectra, with a median spectral index of\n$\\alpha_{150}^{1400}=-0.78\\pm0.015$. The median spectral index becomes slightly\nflatter (increasing from $\\alpha_{150}^{1400}=-0.84$ to\n$\\alpha_{150}^{1400}=-0.75$) with decreasing flux density down to $S_{150}\n\\sim$10 mJy before flattening out and remaining constant below this flux level.\nFor a bright subset of the 150-MHz selected sample we can trace the spectral\nproperties down to lower frequencies using 60-MHz LOFAR observations, finding\ntentative evidence for sources to become flatter in spectrum between 60 and 150\nMHz. Using the deep, multi-frequency data available in the Lockman Hole, we\nidentify a sample of 100 Ultra-steep spectrum (USS) sources and 13 peaked\nspectrum sources. We estimate that up to 21 percent of these could have $z>4$\nand are candidate high-$z$ radio galaxies, but further follow-up observations\nare required to confirm the physical nature of these objects.", "positive": "Kinematics of $z\\geq 6$ galaxies from [CII] line emission: We study the kinematical properties of galaxies in the Epoch of Reionization\nvia the [CII] 158$\\mu$m line emission. The line profile provides information on\nthe kinematics as well as structural properties such as the presence of a disk\nand satellites. To understand how these properties are encoded in the line\nprofile, first we develop analytical models from which we identify disk\ninclination and gas turbulent motions as the key parameters affecting the line\nprofile. To gain further insights, we use \"Althaea\", a highly-resolved ($30\\,\n\\rm pc$) simulated prototypical Lyman Break Galaxy, in the redshift range $z =\n6-7$, when the galaxy is in a very active assembling phase. Based on\nmorphology, we select three main dynamical stages: I) Merger , II) Spiral Disk,\nand III) Disturbed Disk. We identify spectral signatures of merger events,\nspiral arms, and extra-planar flows in I), II), and III), respectively. We\nderive a generalised dynamical mass vs. [CII]-line FWHM relation. If precise\ninformation on the galaxy inclination is (not) available, the returned mass\nestimate is accurate within a factor $2$ ($4$). A Tully-Fisher relation is\nfound for the observed high-$z$ galaxies, i.e. $L_{\\rm[CII]}\\propto\n(FWHM)^{1.80\\pm 0.35}$ for which we provide a simple, physically-based\ninterpretation. Finally, we perform mock ALMA simulations to check the\ndetectability of [CII]. When seen face-on, Althaea is always detected at $>\n5\\sigma$; in the edge-on case it remains undetected because the larger\nintrinsic FWHM pushes the line peak flux below detection limit. This suggests\nthat some of the reported non-detections might be due to inclination effects." }, { "anchor": "Probing the size and charge of Polycyclic Aromatic Hydrocarbons: We present a new method to accurately describe the ionization fraction and\nthe size distribution of polycyclic aromatic hydrocarbons (PAHs) within\nastrophysical sources. To this purpose, we have computed the mid-infrared\nemission spectra of 308 PAH molecules of varying sizes, symmetries, and\ncompactness, generated in a range of radiation fields. We show that the\nintensity ratio of the solo CH out-of-plane bending mode in PAH cations and\nanions (referred to as the 11.0 $\\mu$m band, falling in the 11.0-11.3 $\\mu$m\nregion for cations and anions) to their 3.3 $\\mu$m emission, scales with PAH\nsize, similarly to the scaling of the 11.2/3.3 ratio with the number of carbon\natoms (N$_{\\mathrm{C}}$) for neutral molecules. Among the different PAH\nemission bands, it is the 3.3 $\\mu$m band intensity which has the strongest\ncorrelation with N$_{\\mathrm{C}}$, and drives the reported PAH intensity ratio\ncorrelations with N$_{\\mathrm{C}}$ for both neutral and ionized PAHs. The\n6.2/7.7 intensity ratio, previously adopted to track PAH size, shows no evident\nscaling with N$_{\\mathrm{C}}$ in our large sample. We define a new diagnostic\ngrid space to probe PAH charge and size, using the (11.2+11.0)/7.7 and\n(11.2+11.0)/3.3 PAH intensity ratios respectively. We demonstrate the\napplication of the (11.2+11.0)/7.7 - (11.2+11.0)/3.3 diagnostic grid for\ngalaxies M82 and NGC 253, for the planetary nebula NGC 7027, and the reflection\nnebulae NGC 2023 and NGC 7023. Finally, we provide quantitative relations for\nPAH size determination depending on the ionization fraction of the PAHs and the\nradiation field they are exposed to.", "positive": "BSEC method for unveiling open clusters and its application to Gaia DR3:\n 83 new clusters: Open clusters (OCs) are common in the Milky Way, but most of them remain\nundiscovered. There are numerous techniques, including some machine-learning\nalgorithms, available for the exploration of OCs. However, each method has its\nown limitations and therefore, different approaches to discovering OCs hold\nsignificant value. We develop a comprehensive approach method to automatically\nexplore the data space and identify potential OC candidates with relatively\nreliable membership determination. This approach combines the techniques of\nHDBSCAN, GMM, and a novel cluster member identification technique, 2-color\nconstraint. The new method exhibits efficiency in detecting OCs while ensuring\nprecise determination of cluster memberships. Because the main feature of this\ntechnique is to add an extra constraint for the members of cluster candidates\nusing the homogeneity of color excess, comparing to typical blind search codes,\nit is called Blind Search-Extra Constraint (BSEC) method. It is successfully\napplied to the Gaia Data Release 3, and 83 new OCs with CMDs similar to stellar\nisochrones are found. In addition, this study reports 621 new OC candidates\nincluding at least the main sequence or red giant branch. It is shown that BSEC\ntechnique can discard some false negatives of previous works, which takes about\n3 percentage of known clusters. It shows that color excess (or 2-color)\nconstraint is useful for removing fake cluster member stars and getting more\nprecise CMDs. It makes the CMDs of 15 percent clusters clearer (in particular\nfor the region near turnoff) and therefore is helpful for CMD and stellar\npopulation studies.\n Keywords: galaxy: stellar content, open clusters and associations; stars:\nfundamental parameters" }, { "anchor": "The Herschel-ATLAS: magnifications and physical sizes of\n $500\\,\u03bc$m-selected strongly lensed galaxies: We perform lens modelling and source reconstruction of Submillimeter Array\n(SMA) data for a sample of 12 strongly lensed galaxies selected at 500$\\mu$m in\nthe Herschel Astrophysical Terahertz Large Area Survey H-ATLAS. A previous\nanalysis of the same dataset used a single S\\`ersic profile to model the light\ndistribution of each background galaxy. Here we model the source brightness\ndistribution with an adaptive pixel scale scheme, extended to work in the\nFourier visibility space of interferometry. We also present new SMA\nobservations for seven other candidate lensed galaxies from the H-ATLAS sample.\nOur derived lens model parameters are in general consistent with previous\nfindings. However, our estimated magnification factors, ranging from 3 to 10,\nare lower. The discrepancies are observed in particular where the reconstructed\nsource hints at the presence of multiple knots of emission. We define an\neffective radius of the reconstructed sources based on the area in the source\nplane where emission is detected above 5$\\sigma$. We also fit the reconstructed\nsource surface brightness with an elliptical Gaussian model. We derive a median\nvalue $r_{eff}\\,\\sim 1.77\\,$kpc and a median Gaussian full width at half\nmaximum $\\sim1.47\\,$kpc. After correction for magnification, our sources have\nintrinsic star formation rates SFR$\\,\\sim900-3500\\,M_{\\odot}yr^{-1}$, resulting\nin a median star formation rate surface density\n$\\Sigma_{SFR}\\sim132\\,M_{\\odot}$ yr$^{-1}$ kpc$^{-2}$ (or $\\sim 218\\,M_{\\odot}$\nyr$^{-1}$ kpc$^{-2}$ for the Gaussian fit). This is consistent with what\nobserved for other star forming galaxies at similar redshifts, and is\nsignificantly below the Eddington limit for a radiation pressure regulated\nstarburst.", "positive": "Measuring the AGN sublimation radius with a new approach: reverberation\n mapping of the broad line polarization: Here we give an observational method for measurements of the equatorial\nscattering region radius using variability in the polarized broad lines in Type\n1 active galactic nuclei (AGNs). The polarization in broad lines of Type 1 AGNs\nis mostly caused by equatorial scattering, where specific features allow one to\nseparate its contribution from the total polarized flux. We propose to monitor\nvariability in the polarized line flux and find the time lag between the\nnonpolarized continuum and polarized broad line variability. The distance to\nthe scattering screen can then be determined from the time delay. The method\nwas, for the first time, applied to the observations of the Type 1 AGN Mrk 6,\nand we found that the size of the scattering region in this AGN is around 100\nlight days. That is significantly smaller than the dusty region size estimated\nby the infrared interferometric observations and also larger than known broad\nline region (BLR) size. This indicates that the scattering region lies between\nthe BLR and the dusty region and could be used as a probe of the dust\nsublimation radius." }, { "anchor": "The evolution of circumstellar discs in the Galactic Centre: an\n application to the G-clouds: The Galactic Centre is known to have undergone a recent star formation\nepisode a few Myrs ago, which likely produced many T Tauri stars hosting\ncircumstellar discs. It has been suggested that these discs may be the compact\nand dusty ionized sources identified as ``G-clouds''. Given the Galactic\nCentre's hostile environment, we study the possible evolutionary pathways these\ndiscs experience. We compute new external photoevaporation models applicable to\ndiscs in the Galactic Centre that account for the sub-sonic launching of the\nwind and absorption of UV photons by dust. Using evolutionary disc\ncalculations, we find that photoevaporation's rapid truncation of the disc\ncauses them to accrete onto the central star rapidly. Ultimately, an accreting\ncircumstellar disc has a lifetime $\\lesssim1~$Myr, which would fail to live\nlong enough to explain the G-clouds. However, we identify a new evolutionary\npathway for circumstellar discs in the Galactic Centre. Removal of disc\nmaterial by photoevaporation prevents the young star from spinning down due to\nmagnetic braking, ultimately causing the rapidly spinning young star to torque\nthe disc into a ``decretion disc'' state which prevents accretion. At the same\ntime, any planetary companion in the disc will trap dust outside its orbit,\nshutting down photoevaporation. The disc can survive for up to $\\sim$10 Myr in\nthis state. Encounters with other stars are likely to remove the planet on Myr\ntimescales, causing photoevaporation to restart, giving rise to a G-cloud\nsignature. A giant planet fraction of $\\sim10\\%$ can explain the number of\nobserved G-clouds.", "positive": "The Most Massive Active Black-Holes at z~1.5-3.5 Have High Spins and\n Radiative Efficiencies: The radiative efficiencies ($\\eta$) of 72 luminous unobscured Active Galactic\nNuclei (AGNs) at $z\\sim1.5-3.5$, powered by some of the most massive black\nholes (BHs), are constrained. The analysis is based on accretion disk (AD)\nmodels, which link the continuum luminosity at rest-frame optical wavelengths\nand the black hole mass ($M_{\\rm BH}$) to the accretion rate through the AD,\n$\\dot{M}_{\\rm AD}$. The data are gathered from several literature samples with\ndetailed measurements of the ${\\rm H}\\beta$ emission line complex, observed at\nnear-IR bands. When coupled with standard estimates of bolometric luminosities\n($L_{\\rm bol}$), the analysis suggests high radiative efficiencies, with most\nof the sources showing $\\eta>0.2$ - that is, higher than the commonly assumed\nvalue of 0.1, and the expected value for non-spinning BHs ($\\eta=0.057$). Even\nunder more conservative assumptions regarding $L_{\\rm bol}$ (i.e., $L_{\\rm\nbol}=3\\times \\lambda L_{\\lambda}$[5100$\\AA$]), most of the extremely massive\nBHs in the sample (i.e., $M_{\\rm BH} > 3\\times10^9\\,M_{\\rm \\odot}$) show\nradiative efficiencies which correspond to very high BH spins ($a_{\\rm *}$),\nwith typical values well above $a_{\\rm *}\\simeq0.7$. These results stand in\ncontrast to the predictions of a \"spin-down\"scenario, in which a series of\nrandomly-oriented accretion episodes lead to $a_{\\rm *}\\simeq0$. Instead, the\nanalysis presented here strongly supports a \"spin-up\" scenario, which is driven\nby either prolonged accretion or a series of anisotropically-oriented accretion\nepisodes. Considering the fact that these extreme BHs require long-duration\ncontinuous accretion to account for their high masses, it is argued that the\nmost probable scenario for the SMBHs under study is that of an almost\ncontinuous sequence of randomly- yet not isotropically-oriented accretion\nepisodes." }, { "anchor": "JADES: Discovery of extremely high equivalent width Lyman-alpha emission\n from a faint galaxy within an ionized bubble at z=7.3: We report the discovery of a remarkable Ly$\\alpha$ emitting galaxy at z =\n7.2782, JADES-GS-z7-LA, with EW$_0$(Ly$\\alpha$) $= 388.0 \\pm 88.8$\\AA and UV\nmagnitude -17.0. The spectroscopic redshift is confirmed via rest-frame optical\nlines [O II], H$\\beta$ and [O III] in its JWST/NIRSpec Micro-Shutter Assembly\n(MSA) spectrum. The Ly$\\alpha$ line is detected in both lower resolution PRISM\nas well as medium resolution G140M grating spectra. The LSF-deconvolved\nLy$\\alpha$ FWHM in the grating is $383.9 \\pm 56.2$ km/s and the Ly$\\alpha$\nvelocity offset compared to the systemic redshift is $113.3 \\pm 80.0$ km/s,\nindicative of very little neutral gas or dust within the galaxy. We estimate\nthe Ly$\\alpha$ escape fraction to be >70%. JADES-GS-z7-LA has a O32 ratio of\n$11.1 \\pm 2.2$ and a R23 ratio of $11.2 \\pm 2.6$, consistent with low\nmetallicity and high ionization parameters. Deep NIRCam imaging also revealed a\nclose companion source (separated by 0.23\"), which exhibits similar photometry\nto that of JADES-GS-z7-LA, with a photometric excess in the F410M NIRCam image\nconsistent with [O III]+H$\\beta$ emission at the same redshift. The spectral\nenergy distribution of JADES-GS-z7-LA indicates a \"bursty\" star formation\nhistory, with a low stellar mass of $\\approx 10^7$ $M_\\odot$. Assuming that the\nLy$\\alpha$ transmission through the intergalactic medium is the same as its\nmeasured escape fraction, an ionized region of size > 1.5 pMpc is needed to\nexplain the high Ly$\\alpha$ EW and low velocity offset compared to systemic\nseen in JADES-GS-z7-LA. Owing to its UV-faintness, we show that it is incapable\nof single-handedly ionizing a region large enough to explain its Ly$\\alpha$\nemission. Therefore, we suggest that JADES-GS-z7-LA (and possibly the companion\nsource) may be a part of a larger overdensity, presenting direct evidence of\noverlapping ionized bubbles at $z>7$.", "positive": "Where have all the interstellar silicon carbides gone?: The detection of the 11.3-micron emission feature characteristic of the Si--C\nstretch in carbon-rich evolved stars reveals that silicon carbide (SiC) dust\ngrains are condensed in the outflows of carbon stars. SiC dust could be a\nsignificant constituent of interstellar dust since it is generally believed\nthat carbon stars inject a considerable amount of dust into the interstellar\nmedium (ISM). The presence of SiC dust in the ISM is also supported by the\nidentification of presolar SiC grains of stellar origin in primitive\nmeteorites. However, the 11.3-micron absorption feature of SiC has never been\nseen in the ISM and oxidative destruction of SiC is often invoked. In this work\nwe quantitatively explore the destruction of interstellar SiC dust through\noxidation based on molecular dynamics simulations and density functional theory\ncalculations. We find that the reaction of an oxygen atom with SiC molecules\nand clusters is exothermic and could cause CO-loss. Nevertheless, even if this\nis extrapolable to bulk SiC dust, the destruction rate of SiC dust through\noxidation could still be considerably smaller than the (currently believed)\ninjection rate from carbon stars. Therefore, the lack of the 11.3-micron\nabsorption feature of SiC dust in the ISM remains a mystery. A possible\nsolution may lie in the currently believed stellar injection rate of SiC (which\nmay have been overestimated) and/or the size of SiC dust (which may actually be\nconsiderably smaller than submicron in size)." }, { "anchor": "A Principal component analysis of the diffuse interstellar bands: We present a principal component analysis of 23 line of sight parameters\n(including the strengths of 16 diffuse interstellar bands, DIBs) for a\nwell-chosen sample of single-cloud sightlines representing a broad range of\nenvironmental conditions. Our analysis indicates that the majority ($\\sim$93\\%)\nof the variations in the measurements can be captured by only four parameters\nThe main driver (i.e., the first principal component) is the amount of\nDIB-producing material in the line of sight, a quantity that is extremely well\ntraced by the equivalent width of the $\\lambda$5797 DIB. The second principal\ncomponent is the amount of UV radiation, which correlates well with the\n$\\lambda$5797/$\\lambda$5780 DIB strength ratio. The remaining two principal\ncomponents are more difficult to interpret, but are likely related to the\nproperties of dust in the line of sight (e.g., the gas-to-dust ratio). With our\nPCA results, the DIBs can then be used to estimate these line of sight\nparameters.", "positive": "A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionised gas\n kinematics and abundances: A study of the blue compact dwarf (BCD) galaxy Mrk 996 based on high\nresolution optical VLT VIMOS integral field unit spectroscopy is presented. Mrk\n996 displays multi-component line emission, with most line profiles consisting\nof a narrow, central Gaussian with an underlying broad component. The broad HI\nBalmer component splits into two separate broad components inside a 1\".5 radius\nfrom the nucleus; these are attributed to a two-armed mini-spiral. The rotation\ncurve of Mrk 996 derived from the H\\alpha narrow component yields a total mass\nof 5x10^8 Msol within a radius of 3 kpc.\n The high excitation energy, high critical density [O III] 4363 and [N II]\n5755 lines are only detected from the inner region and exist purely in broad\ncomponent form, implying unusual excitation conditions. Surface brightness,\nradial velocity, and FWHM maps for several emission components are presented. A\nseparate physical analysis of the broad and narrow emission line regions is\nundertaken. We derive an upper limit of 10,000 K for the electron temperature\nof the narrow line gas, together with an electron density of 170 cm^-3, typical\nof normal H II regions. For the broad line component, we estimate a temperature\nof 11,000 K and an electron density of 10^7 cm^-3. The broad line emission\nregions show a N/H enrichment factor of ~20 relative to the narrow line\nregions, but no He/H, O/H, S/H, or Ar/H enrichment is inferred. The dominant\nline excitation mechanism is photoionisation by the ~3000 WR stars and ~150,000\nO-type stars estimated to be present in the core. This is indeed a peculiar\nBCD, with extremely dense zones of gas in the core, through which stellar\noutflows and possible shock fronts permeate contributing to the excitation of\nthe broad line emission. [Abridged]" }, { "anchor": "Implications of Increased Central Mass Surface Densities for the\n Quenching of Low-mass Galaxies: We use the Cosmic Assembly Deep Near-infrared Extragalactic Legacy Survey\n(CANDELS) data to study the relationship between quenching and the stellar mass\nsurface density within the central radius of 1 kpc ($\\Sigma_1$) of low-mass\ngalaxies (stellar mass $M_* \\lesssim 10^{9.5} M_\\odot$) at $0.5 \\leq z < 1.5$.\nOur sample is mass complete down to $\\sim 10^9 M_\\odot$ at $0.5 \\leq z < 1.0$.\nWe compare the mean $\\Sigma_1$ of star-forming galaxies (SFGs) and quenched\ngalaxies (QGs) at the same redshift and $M_*$. We find that low-mass QGs have\nhigher $\\Sigma_1$ than low-mass SFGs, similar to galaxies above $10^{10}\nM_\\odot$. The difference of $\\Sigma_1$ between QGs and SFGs increases slightly\nwith $M_*$ at $M_* \\lesssim 10^{10} M_\\odot$ and decreases with $M_*$ at $M_*\n\\gtrsim 10^{10} M_\\odot$. The turnover mass is consistent with the mass where\nquenching mechanisms transition from internal to environmental quenching. At\n$0.5 \\leq z < 1.0$, we find that the $\\Sigma_1$ of galaxies increases by about\n0.25 dex in the green valley (i.e., the transitioning region from star forming\nto fully quenched), regardless of their $M_*$. Using the observed specific star\nformation rate (sSFR) gradient in the literature as a constraint, we estimate\nthat the quenching timescale (i.e., time spent in the transition) of low-mass\ngalaxies is a few ($\\sim4$) Gyrs at $0.5 \\leq z < 1.0$. The mechanisms\nresponsible for quenching need to gradually quench star formation in an\noutside-in way, i.e., preferentially ceasing star formation in outskirts of\ngalaxies while maintaining their central star formation to increase $\\Sigma_1$.\nAn interesting and intriguing result is the similarity of the growth of\n$\\Sigma_1$ in the green valley between low-mass and massive galaxies, which\nsuggests that the role of internal processes in quenching low-mass galaxies is\na question worthy of further investigation.", "positive": "Evidence for the formation of the young counter-rotating stellar disk\n from gas acquired by IC 719: The formation scenario of extended counter-rotating stellar disks in galaxies\nis still debated. In this paper, we study the S0 galaxy IC 719 known to host\ntwo large-scale counter-rotating stellar disks in order to investigate their\nformation mechanism. We exploit the large field of view and wavelength coverage\nof the Multi Unit Spectroscopic Explorer (MUSE) spectrograph to derive\ntwo-dimensional (2D) maps of the various properties of the counter-rotating\nstellar disks, such as age, metallicity, kinematics, spatial distribution, the\nkinematical and chemical properties of the ionized gas, and the dust map. Due\nto the large wavelength range, and in particular to the presence of the Calcium\nTriplet 8498, 8542, 8662\\AA (CaT hereafter), the spectroscopic analysis allows\nus to separate the two stellar components in great detail. This permits precise\nmeasurement of both the velocity and velocity dispersion of the two components\nas well as their spatial distribution. We derived a 2D map of the age and\nmetallicity of the two stellar components as well as the star formation rate\nand gas-phase metallicity from the ionized gas emission maps. The main stellar\ndisk of the galaxy is kinematically hotter, older, thicker and with larger\nscale-length than the secondary disk. There is no doubt that the latter is\nstrongly linked to the ionized gas component: they have the same kinematics and\nsimilar vertical and radial spatial distribution. This result is in favor of a\ngas accretion scenario over a binary merger scenario to explain the origin of\ncounter-rotation in IC 719. One source of gas that may have contributed to the\naccretion process is the cloud that surrounds IC 719." }, { "anchor": "SDSS-IV DR17: Final Release of MaNGA PyMorph Photometric and Deep\n Learning Morphological Catalogs: We present the MaNGA PyMorph photometric Value Added Catalogue (MPP-VAC-DR17)\nand the MaNGA Deep Learning Morphological VAC (MDLM-VAC-DR17) for the final\ndata release of the MaNGA survey, which is part of the SDSS Data Release 17\n(DR17). The MPP-VAC-DR17 provides photometric parameters from S\\`ersic and\nS\\`ersic+Exponential fits to the 2D surface brightness profiles of the MaNGA\nDR17 galaxy sample in the $g$, $r$, and $i$ bands (e.g. total fluxes, half\nlight radii, bulge-disk fractions, ellipticities, position angles, etc.). The\nMDLM-VAC-DR17 provides Deep Learning-based morphological classifications for\nthe same galaxies. The MDLM-VAC-DR17 includes a number of morphological\nproperties: e.g., a T-Type, a finer separation between elliptical and S0, as\nwell as the identification of edge-on and barred galaxies. While the\nMPP-VAC-DR17 simply extends the MaNGA PyMorph photometric VAC published in the\nSDSS Data Release 15 (MPP-VAC-DR15) to now include galaxies which were added to\nmake the final DR17, the MDLM-VAC-DR17 implements some changes and improvements\ncompared to the previous release (MDLM-VAC-DR15): namely, the low-end of the\nT-Types are better recovered in this new version. The catalogue also includes a\nseparation between Early- or Late-type Galaxies (ETG, LTG), which classifies\nthe two populations in a complementary way to the T-Type, especially at the\nintermediate types (-1 < T-Type < 2), where the T-Type values show a large\nscatter. In addition, $k-$fold based uncertainties on the classifications are\nalso provided. To ensure robustness and reliability, we have also visually\ninspected all the images. We describe the content of the catalogues and show\nsome interesting ways in which they can be combined.", "positive": "Imprints of feedback in young gasless clusters?: We present the results of N-body simulations in which we take the masses,\npositions and velocities of sink particles from five pairs of hydrodynamical\nsimulations of star formation by Dale et al. (2012, 2013) and evolve them for a\nfurther 10Myr. We compare the dynamical evolution of star clusters that formed\nunder the influence of mass-loss driven by photoionization feedback, to the\nevolution of clusters that formed without feedback. We remove any remaining gas\nand follow the evolution of structure in the clusters (measured by the\nQ-parameter), half-mass radius, central density, surface density and the\nfraction of bound stars. There is little discernible difference in the\nevolution of clusters that formed with feedback compared to those that formed\nwithout. The only clear trend is that all clusters which form without feedback\nin the hydrodynamical simulations lose any initial structure over 10Myr,\nwhereas some of the clusters which form with feedback retain structure for the\nduration of the subsequent N-body simulation. This is due to lower initial\ndensities (and hence longer relaxation times) in the clusters from Dale et al.\n(2012, 2013) which formed with feedback, which prevents dynamical mixing from\nerasing substructure. However, several other conditions (such as supervirial\ninitial velocities) also preserve substructure, so at a given epoch one would\nrequire knowledge of the initial density and virial state of the cluster in\norder to determine whether star formation in a cluster has been strongly\ninfluenced by feedback." }, { "anchor": "The Structure of the Planetary Nebula NGC 2371 in the Visible and\n Mid-Infrared: We investigate the structure of the planetary nebula (PN) NGC 2371 using\n[OIII]-5007 imaging taken with the Jacobus Kapteyn 1.0 m telescope, and\n[NII]-6584, [OIII]-5007 and Ha results acquired with the Hubble Space Telescope\n(HST). These are supplemented with archival mid-infrared (MIR) observations\ntaken with the Spitzer Space Telescope (Spitzer). We note the presence of\noff-axis low-ionization spokes along a PA of 65 degrees, and associated collars\nof enhanced [OIII] emission. The spokes appear to consist of dense\ncondensations having low-excitation tails, possibly arising due to UV shadowing\nand/or ram-pressure stripping of material. Line ratios imply that most of the\nemission arises through photo-ionisation, and is unlikely to derive from\npost-shock cooling regions. An analysis of these features in the MIR suggests\nthat they may also be associated with high levels of emission from polycyclic\naromatic hydrocarbons (PAHs), together with various permitted and forbidden\nline transitions. Such high levels of PAH emission, where they are confirmed,\nmay develop as a result of preferentially enhanced FUV pumping of the\nmolecules, or shattering of larger grains within local shocks. Although H2\nemission may also contribute to these trends, it is argued that shock-excited\ntransitions would lead to markedly differing results. We finally note that thin\nfilaments and ridges of [OIII] emission may indicate the presence of shock\nactivity at the limits of the interior envelope, as well as at various\npositions within the shell itself. We also note that radially increasing fluxes\nat 3.6, 5.8 and 8.0 microns, relative to the emission at 4.5 microns, may arise\ndue to enhanced PAH emission in external photo-dissociative regions (PDRs).", "positive": "VALES: IV. Exploring the transition of star formation efficiencies\n between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low\n redshift: In this work we present new APEX/SEPIA Band-5 observations targeting the CO\n($J=2\\text{-}1$) emission line of 24 Herschel-detected galaxies at $z=0.1-0.2$.\nCombining this sample {with} our recent new Valpara\\'iso ALMA Line Emission\nSurvey (VALES), we investigate the star formation efficiencies (SFEs =\nSFR/$M_{\\rm H_{2}}$) of galaxies at low redshift. We find the SFE of our sample\nbridges the gap between normal star-forming galaxies and Ultra-Luminous\nInfrared Galaxies (ULIRGs), which are thought to be triggered by different star\nformation modes. Considering the $\\rm SFE'$ as the SFR and the $L'_{\\rm CO}$\nratio, our data show a continuous and smooth increment as a function of\ninfrared luminosity (or star formation rate) with a scatter about 0.5 dex,\ninstead of a steep jump with a bimodal behaviour. This result is due to the use\nof a sample with a much larger range of sSFR/sSFR$_{\\rm ms}$ using LIRGs, with\nluminosities covering the range between normal and ULIRGs. We conclude that the\nmain parameters controlling the scatter of the SFE in star-forming galaxies are\nthe systematic uncertainty of the $\\alpha_{\\rm CO}$ conversion factor, the gas\nfraction and physical size." }, { "anchor": "Accurately predicting the escape fraction of ionizing photons using\n restframe ultraviolet absorption lines: The fraction of ionizing photons that escape high-redshift galaxies\nsensitively determines whether galaxies reionized the early universe. However,\nthis escape fraction cannot be measured from high-redshift galaxies because the\nopacity of the intergalactic medium is large at high redshifts. Without methods\nto indirectly measure the escape fraction of high-redshift galaxies, it is\nunlikely that we will know what reionized the universe. Here, we analyze the\nfar-ultraviolet (UV) H I (Lyman series) and low-ionization metal absorption\nlines of nine low-redshift, confirmed Lyman continuum emitting galaxies. We use\nthe H I covering fractions, column densities, and dust attenuations measured in\na companion paper to predict the escape fraction of ionizing photons. We find\ngood agreement between the predicted and observed Lyman continuum escape\nfractions (within $1.4\\sigma$) using both the H I and ISM absorption lines. The\nionizing photons escape through holes in the H I, but we show that dust\nattenuation reduces the fraction of photons that escape galaxies. This means\nthat the average high-redshift galaxy likely emits more ionizing photons than\nlow-redshift galaxies. Two other indirect methods accurately predict the escape\nfractions: the Ly$\\alpha$ escape fraction and the optical [O III]/[O II] flux\nratio. We use these indirect methods to predict the escape fraction of a sample\nof 21 galaxies with rest-frame UV spectra but without Lyman continuum\nobservations. Many of these galaxies have low escape fractions ($f_{\\rm esc}\n\\le 1$\\%), but 11 have escape fractions $>1$\\%. The methods presented here will\nmeasure the escape fractions of high-redshift galaxies, enabling future\ntelescopes to determine whether star-forming galaxies reionized the early\nuniverse.", "positive": "Sculpting Andromeda -- made-to-measure models for M31's bar and\n composite bulge: dynamics, stellar and dark matter mass: The Andromeda galaxy (M31) contains a box/peanut bulge (BPB) entangled with a\nclassical bulge (CB) requiring a triaxial modelling to determine the dynamics,\nstellar and dark matter mass. We construct made-to-measure models fitting new\nVIRUS-W IFU bulge stellar kinematic observations, the IRAC-3.6$\\mu$m\nphotometry, and the disc's HI rotation curve. We explore the parameter space\nfor the 3.6$\\mu$m mass-to-light ratio $(\\Upsilon_{3.6})$, the bar pattern speed\n($\\Omega_p$), and the dark matter mass in the composite bulge ($M^B_{DM}$)\nwithin 3.2kpc. Considering Einasto dark matter profiles, we find the best\nmodels for $\\Upsilon_{3.6}=0.72\\pm0.02\\,M_\\odot/L_\\odot$,\n$M^B_{DM}=1.2^{+0.2}_{-0.4}\\times10^{10}M_\\odot$ and\n$\\Omega_p=40\\pm5\\,km/s/kpc$. These models have a dynamical bulge mass of\n$M_{dyn}^B=4.25^{+0.10}_{-0.29}\\times10^{10}M_{\\odot}$ including a stellar mass\nof $M^B=3.09^{+0.10}_{-0.12}\\times10^{10}M_\\odot$(73%), of which the CB has\n$M^{CB}=1.18^{+0.06}_{-0.07}\\times10^{10}M_\\odot$(28%) and the BPB\n$M^{BPB}=1.91\\pm0.06\\times10^{10}M_\\odot$(45%). We also explore models with NFW\nhaloes finding that, while the Einasto models better fit the stellar\nkinematics, the obtained parameters agree within the errors. The $M^B_{DM}$\nvalues agree with adiabatically contracted cosmological NFW haloes with M31's\nvirial mass and radius. The best model has two bulge components with completely\ndifferent kinematics that only together successfully reproduce the observations\n($\\mu_{3.6},\\upsilon_{los},\\sigma_{los},h3,h4$). The modelling includes dust\nabsorption which reproduces the observed kinematic asymmetries. Our results\nprovide new constraints for the early formation of M31 given the lower mass\nfound for the classical bulge and the shallow dark matter profile, as well as\nthe secular evolution of M31 implied by the bar and its resonant interactions\nwith the classical bulge, stellar halo and disc." }, { "anchor": "ALMA and Herschel reveal that X-ray selected AGN and main-sequence\n galaxies have different star formation rate distributions: Using deep Herschel and ALMA observations, we investigate the star formation\nrate (SFR) distributions of X-ray selected AGN host galaxies at 0.53: This paper presents a detailed analysis of two giant Lyman-alpha (Lya) arcs\ndetected near known galaxies at z=3.038 and z=3.754 lensed by the massive\ncluster MACS 1206 (z=0.44). The Lya nebulae revealed in deep MUSE observations\nexhibit a double-peak profile with a dominant red peak that indicates\nexpansion/outflowing motions. One of the arcs stretches over 1' around the\nEinstein radius of the cluster, resolving the velocity field of the\nline-emitting gas on kpc scales around a group of three star-forming galaxies\nof 0.3-1.6L* at z=3.038. The second arc spans 15'' in size, roughly centered\naround a pair of low-mass Lya emitters of ~0.03L* at z=3.754. All three\ngalaxies in the z=3.038 group exhibit prominent damped Lya absorption (DLA) and\nseveral metal absorption lines, in addition to nebular emission lines such as\nHeII1640 and CIII]1906,1908. Extended Lya emission appears to emerge from\nstar-forming regions to larger distances with suppressed surface brightness at\nthe center of each galaxy, suggesting the presence of dusty outflowing cones of\nsize 1-5 kpc across. There are significant spatial variations in the Lya line\nprofile, consistent with the presence of a steep negative velocity gradient in\na continuous flow of high column density gas from star-forming regions into a\nlow-density halo environment. While the observed UV nebular line ratios show no\nevidence of AGN activity in the galaxies, the observed Lya signals can be\nexplained by a combination of resonant scattering and recombination radiation\ndue to photoionization by ionizing photons escaping from the nearby\nstar-forming regions. These observations provide the most detailed insights yet\ninto the kinematics of galactic superwinds associated with star-forming\ngalaxies thought to be responsible for the chemical enrichment in the\nintergalactic medium.", "positive": "Evidence for Co-rotation Origin of Super Metal Rich Stars in\n LAMOST-Gaia: Multiple Ridges with a Similar Slope in phi versus Lz Plane: Super metal-rich (SMR) stars in the solar neighborhood are thought to be born\nin the inner disk and came to present location by radial migration, which is\nmost intense at the co-rotation resonance (CR) of the Galactic bar. In this\nwork, we show evidence for the CR origin of SMR stars in LAMOST-Gaia by\ndetecting six ridges and undulations in the phi versus Lz space coded by median\nVR, following a similar slope of -8 km/s kpc/deg. The slope is predicted by\nMonario et al.'s model for CR of a large and slow Galactic bar. For the first\ntime, we show the variation of angular momentum with azimuths from -10 deg to\n20 deg for two outer and broad undulations with negative VR around -18 km/s\nfollowing this slope. The wave-like pattern with large amplitude outside CR and\na wide peak of the second undulations indicate that minor merger of the\nSagittarius dwarf galaxy with the disk might play a role besides the\nsignificant impact of CR of the Galactic bar." }, { "anchor": "A protostellar system fed by a streamer of 10,500 au length: Binary formation is an important aspect of star formation. One possible route\nfor close-in binary formation is disk fragmentation$^{[1,2,3]}$. Recent\nobservations show small scale asymmetries (<300 au) around young\nprotostars$^{[2,4]}$, although not always resolving the circumbinary disk, are\nlinked to disk phenomena$^{[5,6]}$. In later stages, resolved circumbinary disk\nobservations$^{[7]}$ (<200 au) show similar asymmetries, suggesting the origin\nof the asymmetries arises from binary-disk interactions$^{[8,9,10]}$. We\nobserved one of the youngest systems to study the connection between disk and\ndense core. We find for the first time a bright and clear streamer in\nchemically fresh material (Carbon-chain species) that originates from outside\nthe dense core (>10,500 au). This material connects the outer dense core with\nthe region where asymmetries arise near disk scales. This new structure type,\n10x larger than those seen near disk scales, suggests a different\ninterpretation of previous observations: large-scale accretion flows funnel\nmaterial down to disk scales. These results reveal the under-appreciated\nimportance of the local environment on the formation and evolution of disks in\nearly systems$^{[13,14]}$ and a possible initial condition for the formation of\nannular features in young disks$^{[15,16]}$.", "positive": "MUFASA: The assembly of the red sequence: We examine the growth and evolution of quenched galaxies in the Mufasa\ncosmological hydrodynamic simulations that include an evolving halo mass-based\nquenching prescription, with galaxy colours computed accounting for\nline-of-sight extinction to individual star particles. Mufasa reproduces the\nobserved present-day red sequence reasonably well, including its slope,\namplitude, and scatter. In Mufasa, the red sequence slope is driven entirely by\nthe steep stellar mass-stellar metallicity relation, which independently agrees\nwith observations. High-mass star-forming galaxies blend smoothly onto the red\nsequence, indicating the lack of a well-defined green valley at M*>10^10.5 Mo.\nThe most massive galaxies quench the earliest and then grow very little in mass\nvia dry merging; they attain their high masses at earlier epochs when cold\ninflows more effectively penetrate hot halos. To higher redshifts, the red\nsequence becomes increasingly contaminated with massive dusty star-forming\ngalaxies; UVJ selection subtly but effectively separates these populations. We\nthen examine the evolution of the mass functions of central and satellite\ngalaxies split into passive and star-forming via UVJ. Massive quenched systems\nshow good agreement with observations out to z~2, despite not including a rapid\nearly quenching mode associated with mergers. However, low-mass quenched\ngalaxies are far too numerous at z<1 in Mufasa, indicating that Mufasa strongly\nover-quenches satellites. A challenge for hydrodynamic simulations is to devise\na quenching model that produces enough early massive quenched galaxies and\nkeeps them quenched to z=0, while not being so strong as to over-quench\nsatellites; Mufasa's current scheme fails at the latter." }, { "anchor": "Dust Polarization Toward Embedded Protostars in Ophiuchus with ALMA. II.\n IRAS 16293-2422: We present high-resolution (~ 35 au) ALMA Band 6 1.3 mm dust polarization\nobservations of IRAS 16293. These observations spatially resolve the dust\npolarization across the two protostellar sources and toward the filamentary\nstructures between them. The dust polarization and inferred magnetic field have\ncomplicated structures throughout the region. In particular, we find that the\nmagnetic field is aligned parallel to three filamentary structures. We\ncharacterize the physical properties of the filamentary structure that bridges\nIRAS 16293A and IRAS 16293B and estimate a magnetic field strength of 23-78 mG\nusing the Davis-Chandrasekhar-Fermi method. We construct a toy model for the\nbridge material assuming that the young stars dominate the mass and\ngravitational potential of the system. We find that the expected gas flow to\neach star is of comparable order to the Alfven speed, which suggests that the\nfield may be regulating the gas flow. We also find that the bridging material\nshould be depleted in ~ 1000 yr. If the bridge is part of the natal filament\nthat formed the stars, then it must have accreted new material. Alternatively,\nthe bridge could be a transient structure. Finally, we show that the 1.3 mm\npolarization morphology of the optically thick IRAS 16293B system is\nqualitatively similar to dust self-scattering. Based on similar polarization\nmeasurements at 6.9 mm, we propose that IRAS 16293B has produced a substantial\npopulation of large dust grains with sizes between 200 and 2000 um.", "positive": "ALMA Observations of a Quiescent Molecular Cloud in the Large Magellanic\n Cloud: We present high-resolution (sub-parsec) observations of a giant molecular\ncloud in the nearest star-forming galaxy, the Large Magellanic Cloud. ALMA Band\n6 observations trace the bulk of the molecular gas in $^{12}$CO(2-1) and high\ncolumn density regions in $^{13}$CO(2-1). Our target is a quiescent cloud (PGCC\nG282.98-32.40, which we refer to as the \"Planck cold cloud\" or PCC) in the\nsouthern outskirts of the galaxy where star-formation activity is very low and\nlargely confined to one location. We decompose the cloud into structures using\na dendrogram and apply an identical analysis to matched-resolution cubes of the\n30 Doradus molecular cloud (located near intense star formation) for\ncomparison. Structures in the PCC exhibit roughly 10 times lower surface\ndensity and 5 times lower velocity dispersion than comparably sized structures\nin 30 Dor, underscoring the non-universality of molecular cloud properties. In\nboth clouds, structures with relatively higher surface density lie closer to\nsimple virial equilibrium, whereas lower surface density structures tend to\nexhibit super-virial line widths. In the PCC, relatively high line widths are\nfound in the vicinity of an infrared source whose properties are consistent\nwith a luminous young stellar object. More generally, we find that the smallest\nresolved structures (\"leaves\") of the dendrogram span close to the full range\nof line widths observed across all scales. As a result, while the bulk of the\nkinetic energy is found on the largest scales, the small-scale energetics tend\nto be dominated by only a few structures, leading to substantial scatter in\nobserved size-linewidth relationships." }, { "anchor": "The edges of galaxies in the Fornax Cluster: Fifty percent smaller and\n denser compared to the field: Physically motivated measurements are crucial for understanding galaxy growth\nand the role of the environment on their evolution. In particular, the growth\nof galaxies as measured by their size or radial extent provides an empirical\napproach for addressing this issue. However, the established definitions of\ngalaxy size used for nearly a century are ill-suited for these studies because\nof a previously ignored bias. The conventionally-measured radii consistently\nmiss the diffuse, outer extensions of stellar emission which harbour key\nsignatures of galaxy growth, including star formation and gas accretion or\nremoval. This issue is addressed by examining low surface brightness\ntruncations or galaxy \"edges\" as a physically motivated tracer of size based on\nstar formation thresholds. Our total sample consists of $\\sim900$ galaxies with\nstellar masses ranging from $10^5 M_{\\odot} < M_{\\star} < 10^{11} M_{\\odot}$.\nThis sample of nearby cluster, group satellite and nearly isolated field\ngalaxies was compiled using multi-band imaging from the Fornax Deep Survey,\ndeep IAC Stripe 82 and Dark Energy Camera Legacy Surveys. Across the full mass\nrange studied, we find that compared to the field, the edges of galaxies in the\nFornax Cluster are located at 50% smaller radii and the average stellar surface\ndensity at the edges are two times higher. These results are consistent with\nthe rapid removal of loosely bound neutral hydrogen (HI) in hot, crowded\nenvironments which truncates galaxies outside-in earlier, preventing the\nformation of more extended sizes and lower density edges. In fact, we find that\ngalaxies with lower HI fractions have edges with higher stellar surface\ndensity. Our results highlight the importance of deep imaging surveys to study\nthe low surface brightness imprints of the large scale structure and\nenvironment on galaxy evolution.", "positive": "A Population of Bona Fide Intermediate Mass Black Holes Identified as\n Low Luminosity Active Galactic Nuclei: Nearly every massive galaxy harbors a supermassive black hole (SMBH) in its\nnucleus. SMBH masses are millions to billions $M_{\\odot}$, and they correlate\nwith properties of spheroids of their host galaxies. While the SMBH growth\nchannels, mergers and gas accretion, are well established, their origin remains\nuncertain: they could have either emerged from massive \"seeds\" ($10^5-10^6\nM_{\\odot}$) formed by direct collapse of gas clouds in the early Universe or\nfrom smaller ($100 M_{\\odot}$) black holes, end-products of first stars. The\nlatter channel would leave behind numerous intermediate mass black holes\n(IMBHs, $10^2-10^5 M_{\\odot}$). Although many IMBH candidates have been\nidentified, none is accepted as definitive, thus their very existence is still\ndebated. Using data mining in wide-field sky surveys and applying dedicated\nanalysis to archival and follow-up optical spectra, we identified a sample of\n305 IMBH candidates having masses $3\\times10^4 32 (which roughly corresponds to Eddington ratios $\\gtrsim 1$%)\nAGN and sample-averaged black hole accretion rate ($\\rm \\overline{BHAR}$)\ndecrease with $\\rm D_{n}4000$ among $\\rm D_{n}4000$ $\\lesssim$ 1.9 galaxies,\nsuggesting a higher level of AGN activity among younger galaxies, which\nsupports the stellar mass loss fuelling scenario. For the oldest and most\nmassive galaxies at $z = 0-0.35$, this decreasing trend is not present anymore.\nWe found that, among these most massive galaxies at low redshift, the fraction\nof low specific-accretion-rate (31 $<$ log $L_{\\rm X}$/$M_\\star$ $<$ 32) AGNs\nincreases with $\\rm D_{n}4000$, which may be associated with additional\nfuelling from hot halo gas and/or enhanced accretion capability.", "positive": "Detection of Interstellar HC$_4$NC and an Investigation of\n Isocyanopolyyne Chemistry under TMC-1 Conditions: We report an astronomical detection of HC$_4$NC for the first time in the\ninterstellar medium with the Green Bank Telescope toward the TMC-1 molecular\ncloud with a minimum significance of $10.5 \\sigma$. The total column density\nand excitation temperature of HC$_4$NC are determined to be\n$3.29^{+8.60}_{-1.20}\\times 10^{11}$ cm$^{-2}$ and $6.7^{+0.3}_{-0.3}$ K,\nrespectively, using the MCMC analysis. In addition to HC$_4$NC, HCCNC is\ndistinctly detected whereas no clear detection of HC$_6$NC is made. We propose\nthat the dissociative recombination of the protonated cyanopolyyne,\nHC$_5$NH$^+$, and the protonated isocyanopolyyne, HC$_4$NCH$^+$, are the main\nformation mechanisms for HC$_4$NC while its destruction is dominated by\nreactions with simple ions and atomic carbon. With the proposed chemical\nnetworks, the observed abundances of HC$_4$NC and HCCNC are reproduced\nsatisfactorily." }, { "anchor": "Probing the link between quenching and morphological evolution: We use a semianalytic model of galaxy formation to compare the predictions of\ntwo quenching scenarios: halo quenching and black-hole (BH) quenching. After\ncalibrating both models so that they fit the mass function of galaxies, BH\nquenching is in better agreement with the fraction of passive galaxies as a\nfunction of stellar mass $M_*$ and with the galaxy morphological distribution\non a star-formation-rate vs. $M_*$ diagram. Besides this main finding, there\nare two other results from this research. First, a successful BH-quenching\nmodel requires that minor mergers contribute to the growth of supermassive BHs.\nIf galaxies that reach high $M_*$ through repeated minor mergers are not\nquenched, there are too many blue galaxies at high masses. Second, the growth\nof BHs in mergers must become less efficient at low masses in order to\nreproduce the $M_{\\rm BH}$--$M_*$ relation and the passive fraction as a\nfunction of $M_*$, in agreement with the idea that supernovae prevent efficient\nBH growth in systems with low escape speeds. Our findings are consistent with a\nquasar-feedback scenario in which BHs grow until they are massive enough to\nblow away the cold gas in their host galaxies and to heat the hot\ncircumgalactic medium to such high entropy that its cooling time becomes long.\nThey also support the notion that quenching and maintenance correspond to\ndifferent feedback regimes.", "positive": "Retention of Stellar-Mass Black Holes in Globular Clusters: Globular clusters should be born with significant numbers of stellar-mass\nblack holes (BHs). It has been thought for two decades that very few of these\nBHs could be retained through the cluster lifetime. With masses ~10 MSun, BHs\nare ~20 times more massive than an average cluster star. They segregate into\nthe cluster core, where they may eventually decouple from the remainder of the\ncluster. The small-N core then evaporates on a short timescale. This is the\nso-called Spitzer instability. Here we present the results of a full dynamical\nsimulation of a globular cluster containing many stellar-mass BHs with a\nrealistic mass spectrum. Our Monte Carlo simulation code includes detailed\ntreatments of all relevant stellar evolution and dynamical processes. Our main\nfinding is that old globular clusters could still contain many BHs at present.\nIn our simulation, we find no evidence for the Spitzer instability. Instead,\nmost of the BHs remain well-mixed with the rest of the cluster, with only the\ninnermost few tens of BHs segregating significantly. Over the 12 Gyr evolution,\nfewer than half of the BHs are dynamically ejected through strong binary\ninteractions in the cluster core. The presence of BHs leads to long-term\nheating of the cluster, ultimately producing a core radius on the high end of\nthe distribution for Milky Way globular clusters (and those of other galaxies).\nA crude extrapolation from our model suggests that the BH--BH merger rate from\nglobular clusters could be comparable to the rate in the field." }, { "anchor": "Radio continuum observations of the Leo Triplet at 2.64 GHz: Aims. The magnetic fields of the member galaxies NGC 3628 and NGC 3627 show\nmorphological peculiarities, suggesting that interactions within the group may\nbe caused by stripping of the magnetic field. This process could supply the\nintergalactic space with magnetised material, a scenario considered as a\npossible source of intergalactic magnetic fields (as seen eg. in the Taffy\npairs of galaxies). Additionally, the plumes are likely to be the tidal dwarf\ngalaxy candidates.\n Methods. We performed radio continuum mapping observations at 2.64 GHz using\nthe 100-m Effelsberg radio telescope. We obtained total power and polarised\nintensity maps of the Triplet. These maps were analysed together with the\narchive data, and the magnetic field strength (as well as the magnetic energy\ndensity) was estimated.\n Results. Extended emission was not detected either in the total power or the\npolarised intensity maps. We obtained upper limits of the magnetic field\nstrength and the energy density of the magnetic field in the Triplet. We\ndetected emission from the easternmost clump and determined the strength of its\nmagnetic field. In addition, we measured integrated fluxes of the member\ngalaxies at 2.64 GHz and estimated their total magnetic field strengths.\n Conclusions. We found that the tidal tail hosts a tidal dwarf galaxy\ncandidate that possesses a detectable magnetic field with a non-zero ordered\ncomponent. Extended radio continuum emission, if present, is weaker than the\nreached confusion limit. The total magnetic field strength does not exceed 2.8\n{\\mu}G and the ordered component is lower than 1.6 {\\mu}G.", "positive": "The Integral Field View of the Orion Nebula: This paper reviews the major advances achieved in the Orion Nebula through\nthe use of integral field spectroscopy (IFS). Since the early work of\nVasconcelos and collaborators in 2005, this technique has facilitated the\ninvestigation of global properties of the nebula and its morphology, providing\nnew clues to better constrain its 3D structure. IFS has led to the discovery of\nshock-heated zones at the leading working surfaces of prominent Herbig-Haro\nobjects as well as the first attempt to determine the chemical composition of\nOrion protoplanetary disks, also known as proplyds. The analysis of these\nmorphologies using IFS has given us new insights into the abundance discrepancy\nproblem, a long-standing and unresolved issue that casts doubt on the\nreliability of current methods used for the determination of metallicities in\nthe universe from the analysis of H II regions. Results imply that high-density\nclumps and high-velocity flows may play an active role in the production of\nsuch discrepancies. Future investigations based on the large-scale IFS mosaic\nof Orion will be very valuable for exploring how the integrated effect of\nsmall-scale structures may have impact at larger scales in the framework of\nstar-forming regions." }, { "anchor": "Fingerprints of Stellar Populations in the Near-Infrared: An Optimised\n Set of Spectral Indices in the JHK-Bands: Stellar population studies provide unique clues to constrain galaxy formation\nmodels. So far, detailed studies based on absorption line strengths have mainly\nfocused on the optical spectral range although many diagnostic features are\npresent in other spectral windows. In particular, the near-infrared (NIR) can\nprovide a wealth of information about stars, such as evolved giants, that have\nless evident optical signatures. Due to significant advances in NIR\ninstrumentation and extension of spectral libraries and stellar population\nsynthesis (SPS) models to this domain, it is now possible to perform in-depth\nstudies of spectral features in the NIR to a high level of precision. In the\npresent work, taking advantage of state-of-the-art SPS models covering the NIR\nspectral range, we introduce a new set of NIR indices constructed to be\nmaximally sensitive to the main stellar population parameters, namely age,\nmetallicity and initial mass function (IMF). We fully characterize the new\nindices against these parameters as well as their sensitivity to individual\nelemental abundance variations, velocity dispersion broadening, wavelength\nshifts, signal-to-noise ratio and flux calibration. We also present, for the\nfirst time, a method to ensure that the analysis of spectral indices is not\naffected by sky contamination, which is a major challenge when dealing with NIR\nspectroscopy. Moreover, we discuss two main applications: (i) the ability of\nsome NIR spectral indices to constrain the shape of the low-mass IMF and (ii)\ncurrent issues in the analysis of NIR spectral indices for future developments\nof SPS modelling.", "positive": "Hubble Space Telescope Imaging of the Active Dwarf Galaxy RGG 118: RGG 118 (SDSS 1523+1145) is a nearby ($z=0.0243$), dwarf disk galaxy\n($M_{\\ast}\\approx2\\times10^{9} M_{\\odot}$) found to host an active $\\sim50,000$\nsolar mass black hole at its core (Baldassare et al. 2015). RGG 118 is one of a\ngrowing collective sample of dwarf galaxies known to contain active galactic\nnuclei -- a group which, until recently, contained only a handful of objects.\nHere, we report on new \\textit{Hubble Space Telescope} Wide Field Camera 3 UVIS\nand IR imaging of RGG 118, with the main goal of analyzing its structure. Using\n2-D parametric modeling, we find that the morphology of RGG 118 is best\ndescribed by an outer spiral disk, inner component consistent with a\npseudobulge, and central PSF. The luminosity of the PSF is consistent with the\ncentral point source being dominated by the AGN. We measure the luminosity and\nmass of the \"pseudobulge\" and confirm that the central black hole in RGG 118 is\nunder-massive with respect to the $M_{BH}-M_{\\rm bulge}$ and $M_{BH}-L_{\\rm\nbulge}$ relations. This result is consistent with a picture in which black\nholes in disk-dominated galaxies grow primarily through secular processes." }, { "anchor": "NGC 6791: a probable bulge cluster without multiple populations: NGC 6791 is a unique stellar cluster, key to our understanding of both the\nmultiple stellar population phenomenon and the evolution and assembly of the\nGalaxy. However, despite many investigations, its nature is still very\ncontroversial. Geisler et al. (2012) found evidence suggesting it was the first\nopen cluster to possess multiple populations but several subsequent studies did\nnot corroborate this. It has also been considered a member of the thin or thick\ndisk or even the bulge, and both as an open or globular cluster or even the\nremnant of a dwarf galaxy. Here, we present and discuss detailed abundances\nderived from high resolution spectra obtained with UVES at VLT and HIRES at\nKeck of 17 evolved stars of this cluster. We obtained a mean\n[Fe/H]=+0.313+-0.005, in good agreement with recent estimates, and with no\nindication of star-to-star metallicity variation, as expected. We also did not\nfind any variation in Na, in spite of having selected the very same stars as in\nGeisler et al. (2012), where a Na variation was claimed. This points to the\npresence of probable systematics in the lower resolution spectra of this very\nhigh metallicity cluster analysed in that work. In fact, we find no evidence\nfor an intrinsic spread in any element, corroborating recent independent APOGEE\ndata. The derived abundances indicate that NGC 6791 very likely formed in the\nGalactic Bulge and that the proposed association with the Thick Disk is\nunlikely, despite its present Galactic location. We confirm the most recent\nhypothesis suggesting that the cluster could have formed in the Bulge and\nradially migrated to its current location, which appears the best explanation\nfor this intriguing object.", "positive": "An Infrared Study of the Dust Properties and Geometry of the Arched\n Filaments HII Region with SOFIA/FORCAST: Massive stellar clusters provide radiation ($\\mathrm{\\sim\n10^7-10^8~L_{\\odot}}$) and winds ($\\mathrm{\\sim 1000~km/s}$) that act to heat\ndust and shape their surrounding environment. In this paper, the Arched\nFilaments in the Galactic center were studied to better understand the\ninfluence of the Arches cluster on its nearby interstellar medium (ISM). The\nArched Filaments were observed with the Faint Object InfraRed CAMera for the\nSOFIA Telescope (FORCAST) at 19.7, 25.2, 31.5, and 37.1 $\\mu$m.\nColor-temperature maps of the region created with the 25.2 and 37.1 $\\mu$m data\nreveal relatively uniform dust temperatures (70-100 K) over the extent of the\nfilaments ($\\sim 25$ pc). Distances between the cluster and the filaments were\ncalculated assuming equilibrium heating of standard size ISM dust grains\n($\\sim$0.1 $\\mu$m). The distances inferred by this method are in conflict with\nthe projected distance between the filaments and the cluster, although this\ninconsistency can be explained if the characteristic grain size in the\nfilaments is smaller ($\\sim$0.01 $\\mu$m) than typical values. DustEM models of\nselected locations within the filaments show evidence of depleted abundances of\npolycyclic aromatic hydrocarbons (PAHs) by factors of $\\sim$1.6-10 by mass\ncompared to the diffuse ISM. The evidence for both PAH depletion and a smaller\ncharacteristic grain size points to processing of the ISM within the filaments.\nWe argue that the eroding of dust grains within the filaments is not likely\nattributable to the radiation or winds from the Arches cluster, but may be\nrelated to the physical conditions in the Galactic center." }, { "anchor": "Long-term optical flux and colour variability in quasars: We have used optical V and R band observations from the Massive Compact Halo\nObject (MACHO) project on a sample of 59 quasars behind the Magellanic clouds\nto study their long term optical flux and colour variations. These quasars\nlying in the redshift range of 0.2 < z < 2.8 and having apparent V band\nmagnitudes between 16.6 and 20.1 mag have observations ranging from 49 to 1353\nepochs spanning over 7.5 years with frequency of sampling between 2 to 10 days.\nAll the quasars show variability during the observing period. The normalized\nexcess variance (Fvar) in V and R bands are in the range 0.2% < Fvar < 1.6% and\n0.1% < Fvar < 1.5%. In a large fraction of the sources, Fvar is larger in the\nV-band compared to the R-band. From the z-transformed discrete cross\ncorrelation function analysis, we find that there is no lag between the V and\nR-band variations. Adopting the Markov Chain Monte Carlo (MCMC) approach, and\nproperly taking into account the correlation between the errors in colours and\nmagnitudes, it is found that majority of the sources show a bluer when brighter\ntrend, while a minor fraction of quasars show the opposite behaviour. This is\nsimilar to the results obtained from other two independent algorithms namely\nthe weighted linear least squares fit (FITEXY) and the bivariate correlated\nerrors and intrinsic scatter regression (BCES). However, the ordinary least\nsquares (OLS) fit normally used in the colour variability studies of quasars,\nindicates that all the quasars studied here show a bluer when brighter trend.\nIt is therefore very clear that OLS algorithm cannot be used for the study of\ncolour variability in quasars.", "positive": "The Evolution of Galaxy Number Density at z < 8 and its Implications: The evolution of the number density of galaxies in the universe, and thus\nalso the total number of galaxies, is a fundamental question with implications\nfor a host of astrophysical problems including galaxy evolution and cosmology.\nHowever there has never been a detailed study of this important measurement,\nnor a clear path to answer it. To address this we use observed galaxy stellar\nmass functions up to $z\\sim8$ to determine how the number densities of galaxies\nchanges as a function of time and mass limit. We show that the increase in the\ntotal number density of galaxies ($\\phi_{\\rm T}$), more massive than M$_{*} =\n10^{6}$ M_0, decreases as $\\phi_{\\rm T} \\sim t^{-1}$, where $t$ is the age of\nthe universe. We further show that this evolution turns-over and rather\nincreases with time at higher mass lower limits of M$_{*}>10^{7}$ M_0. By using\nthe M$_{*}=10^{6}$ M_0 lower limit we further show that the total number of\ngalaxies in the universe up to $z = 8$ is $2.0^{+0.7}_{-0.6} \\times 10^{12}$\n(two trillion), almost a factor of ten higher than would be seen in an all sky\nsurvey at Hubble Ultra-Deep Field depth. We discuss the implications for these\nresults for galaxy evolution, as well as compare our results with the latest\nmodels of galaxy formation. These results also reveal that the cosmic\nbackground light in the optical and near-infrared likely arise from these\nunobserved faint galaxies. We also show how these results solve the question of\nwhy the sky at night is dark, otherwise known as Olbers' paradox." }, { "anchor": "Galaxy Build-up in the first 1.5 Gyr of Cosmic History: Insights from\n the Stellar Mass Function at $z\\sim4-9$ from JWST NIRCam Observations: Combining the public JWST/NIRCam imaging programs CEERS, PRIMER and JADES,\nspanning a total area of $\\sim$500 arcmin$^2$, we obtain a sample of $>$30,000\ngalaxies at $z\\sim4-9$ that allows us to perform a complete, rest-optical\nselected census of the galaxy population at $z>3$. Comparing the stellar mass\n$M_*$ and the UV-slope $\\beta$ distributions between JWST- and HST-selected\nsamples, we generally find very good agreement and no significant biases.\nNevertheless, JWST enables us to probe a small population of UV-red galaxies\nthat was missing from previous HST-based LBG samples. We measure galaxy stellar\nmass functions (SMFs) at $z\\sim4-9$ and show that they are broadly consistent\nwith existing literature results. However, UV-red galaxies dominate the\nhigh-mass end of the SMF at least out to $z\\sim6$. In particular the most\nmassive galaxies typically show very red colors between\n$\\lambda_{obs}\\sim1.5\\mu$m and $\\sim4.5\\mu$m, and thus JWST's unprecedented\nresolution and sensitivity at these wavelengths yields more accurate\nconstraints on their abundance and masses. The implied redshift evolution of\nthe high-mass end of the SMF suggests a rapid build-up of massive dust-obscured\nas well as quiescent galaxies from $z\\sim6$ to $z\\sim4$ as well as an enhanced\nefficiency of star formation towards earlier times ($z\\gtrsim6$). We find the\nSMFs to be steep over the entire redshift range, and slightly steepening with\nredshift from $z\\sim 4-6$, reaching values of $\\approx-2$ at $z\\gtrsim6$.\nFinally, we show that the galaxy mass density grows by a factor $\\sim20\\times$\nin the $\\sim1$ Gyr of cosmic time from $z\\sim9$ to $z\\sim4$. Our results\nemphasize the importance of rest-frame optically-selected samples in inferring\naccurate distributions of physical properties and studying the mass build-up of\ngalaxies in the first 1.5 Gyr of cosmic history.", "positive": "LOFAR MSSS: Discovery of a 2.56 Mpc giant radio galaxy associated with a\n disturbed galaxy group: We report on the discovery in the LOFAR Multifrequency Snapshot Sky Survey\n(MSSS) of a giant radio galaxy (GRG) with a projected size of $2.56 \\pm 0.07$\nMpc projected on the sky. It is associated with the galaxy triplet UGC 9555,\nwithin which one is identified as a broad-line galaxy in the Sloan Digital Sky\nSurvey (SDSS) at a redshift of $0.05453 \\pm 1 \\times 10^{-5} $, and with a\nvelocity dispersion of $215.86 \\pm 6.34$ km/s. From archival radio observations\nwe see that this galaxy hosts a compact flat-spectrum radio source, and we\nconclude that it is the active galactic nucleus (AGN) responsible for\ngenerating the radio lobes. The radio luminosity distribution of the jets, and\nthe broad-line classification of the host AGN, indicate this GRG is orientated\nwell out of the plane of the sky, making its physical size one of the largest\nknown for any GRG. Analysis of the infrared data suggests that the host is a\nlenticular type galaxy with a large stellar mass\n($\\log~\\mathrm{M}/\\mathrm{M}_\\odot = 11.56 \\pm 0.12$), and a moderate star\nformation rate ($1.2 \\pm 0.3~\\mathrm{M}_\\odot/\\mathrm{year}$). Spatially\nsmoothing the SDSS images shows the system around UGC 9555 to be significantly\ndisturbed, with a prominent extension to the south-east. Overall, the evidence\nsuggests this host galaxy has undergone one or more recent moderate merger\nevents and is also experiencing tidal interactions with surrounding galaxies,\nwhich have caused the star formation and provided the supply of gas to trigger\nand fuel the Mpc-scale radio lobes." }, { "anchor": "Metallicity-dependendent kinematics and morphology of the Milky Way\n bulge: We use N-body chemo-dynamic simulations to study the coupling between\nmorphology, kinematics and metallicity of the bar/bulge region of our Galaxy.\nWe make qualitative comparisons of our results with available observations and\nfind very good agreement. We conclude that this region is complex, since it\ncomprises several stellar components with different properties -- i.e. a\nboxy/peanut bulge, thin and thick disc components, and, to lesser extents, a\ndisky pseudobulge, a stellar halo and a small classical bulge -- all cohabiting\nin dynamical equilibrium. Our models show strong links between kinematics and\nmetallicity, or morphology and metallicity, as already suggested by a number of\nrecent observations. We discuss and explain these links.", "positive": "The Star Cluster System in the Local Group Starburst Galaxy IC 10: We present a survey of star clusters in the halo of IC 10, a starburst galaxy\nin the Local Group based on Subaru R band images and NOAO Local Group Survey\nUBVRI images. We find five new star clusters. All these star clusters are\nlocated far from the center of IC 10, while previously known star clusters are\nmostly in the main body. Interestingly the distribution of these star clusters\nshows an asymmetrical structure elongated along the east and south-west\ndirection. We derive UBVRI photometry of 66 star clusters including these new\nstar clusters as well as previously known star clusters. Ages of the star\nclusters are estimated from the comparison of their UBVRI spectral energy\ndistribution with the simple stellar population models. We find that the star\nclusters in the halo are all older than 1 Gyr, while those in the main body\nhave various ages from very young (several Myr) to old (>1 Gyr). The young\nclusters (<10 Myr) are mostly located in the H{\\alpha} emission regions and are\nconcentrated on a small region at 2' in the south-east direction from the\ngalaxy center, while the old clusters are distributed in a wider area than the\ndisk. Intermediate-age clusters (~100 Myr) are found in two groups. One is\nclose to the location of the young clusters and the other is at ~4' from the\nlocation of the young clusters. The latter may be related with past merger or\ntidal interaction." }, { "anchor": "Limits to Rest-Frame Ultraviolet Emission From Far-Infrared-Luminous z~6\n Quasar Hosts: We report on a Hubble Space Telescope search for rest-frame ultraviolet\nemission from the host galaxies of five far-infrared-luminous $z\\simeq{}6$\nquasars and the $z=5.85$ hot-dust free quasar SDSS J0005-0006. We perform 2D\nsurface brightness modeling for each quasar using a Markov-Chain Monte-Carlo\nestimator, to simultaneously fit and subtract the quasar point source in order\nto constrain the underlying host galaxy emission. We measure upper limits for\nthe quasar host galaxies of $m_J>22.7$ mag and $m_H>22.4$ mag, corresponding to\nstellar masses of $M_\\ast<2\\times10^{11}M_\\odot$. These stellar mass limits are\nconsistent with the local $M_{\\textrm{BH}}$-$M_\\ast$ relation. Our flux limits\nare consistent with those predicted for the UV stellar populations of\n$z\\simeq6$ host galaxies, but likely in the presence of significant dust\n($\\langle A_{\\mathrm{UV}}\\rangle\\simeq 2.6$ mag). We also detect a total of up\nto 9 potential $z\\simeq6$ quasar companion galaxies surrounding five of the six\nquasars, separated from the quasars by 1.4''-3.2'', or 8.4-19.4 kpc, which may\nbe interacting with the quasar hosts. These nearby companion galaxies have UV\nabsolute magnitudes of -22.1 to -19.9 mag, and UV spectral slopes $\\beta$ of\n-2.0 to -0.2, consistent with luminous star-forming galaxies at $z\\simeq6$.\nThese results suggest that the quasars are in dense environments typical of\nluminous $z\\simeq6$ galaxies. However, we cannot rule out the possibility that\nsome of these companions are foreground interlopers. Infrared observations with\nthe James Webb Space Telescope will be needed to detect the $z\\simeq6$ quasar\nhost galaxies and better constrain their stellar mass and dust content.", "positive": "Galaxy evolution in the mid-infrared green valley: a case of the A2199\n supercluster: We study the mid-infrared (MIR) properties of the galaxies in the A2199\nsupercluster at z = 0.03 to understand the star formation activity of galaxy\ngroups and clusters in the supercluster environment. Using the Wide-field\nInfrared Survey Explorer data, we find no dependence of mass-normalized\nintegrated SFRs of galaxy groups/clusters on their virial masses. We classify\nthe supercluster galaxies into three classes in the MIR color-luminosity\ndiagram: MIR blue cloud (massive, quiescent and mostly early-type), MIR\nstar-forming sequence (mostly late-type), and MIR green valley galaxies. These\nMIR green valley galaxies are distinguishable from the optical green valley\ngalaxies, in the sense that they belong to the optical red sequence. We find\nthat the fraction of each MIR class does not depend on virial mass of each\ngroup/cluster. We compare the cumulative distributions of surface galaxy number\ndensity and cluster/group-centric distance for the three MIR classes. MIR green\nvalley galaxies show the distribution between MIR blue cloud and MIR SF\nsequence galaxies. However, if we fix galaxy morphology, early- and late-type\nMIR green valley galaxies show different distributions. Our results suggest a\npossible evolutionary scenario of these galaxies: 1) Late-type MIR SF sequence\ngalaxies -> 2) Late-type MIR green valley galaxies -> 3) Early-type MIR green\nvalley galaxies -> 4) Early-type MIR blue cloud galaxies. In this sequence,\nstar formation of galaxies is quenched before the galaxies enter the MIR green\nvalley, and then morphological transformation occurs in the MIR green valley." }, { "anchor": "Smooth HI Low Column Density Outskirts In Nearby Galaxies: The low column density gas at the outskirts of galaxies as traced by the 21\ncm hydrogen line emission (HI) represents the interface between galaxies and\nthe intergalactic medium, i.e., where galaxies are believed to get their supply\nof gas to fuel future episodes of star formation. Photoionization models\npredict a break in the radial profiles of HI at a column density of 5x10E+19\ncm^-2 due to the lack of self-shielding against extragalactic ionizing photons.\nTo investigate the prevalence of such breaks in galactic disks and to\ncharacterize what determines the potential \"edge\" of the HI disks, we study the\nazimuthally-averaged HI column density profiles of 17 nearby galaxies from The\nHI Nearby Galaxy Survey (THINGS) and supplemented in two cases with published\nHydrogen Accretion in LOcal GAlaxieS (HALOGAS) data. To detect potential faint\nHI emission that would otherwise be undetected using conventional moment map\nanalysis, we line up individual profiles to the same reference velocity and\naverage them azimuthally to derive stacked radial profiles. To do so, we use\nmodel velocity fields created from a simple extrapolation of the rotation\ncurves to align the profiles in velocity at radii beyond the extent probed with\nthe sensitivity of traditional integrated HI maps. With this method, we improve\nour sensitivity to outer-disk HI emission by up to an order of magnitude.\nExcept for a few disturbed galaxies, none show evidence for a sudden change in\nthe slope of the HI radial profiles, the alleged signature of ionization by the\nextragalactic background.", "positive": "Recovering interstellar gas properties with HI spectral lines: A\n comparison between synthetic spectra and 21-SPONGE: We analyze synthetic neutral hydrogen (HI) absorption and emission spectral\nlines from a high- resolution, three-dimensional hydrodynamical simulation to\nquantify how well observational methods recover the physical properties of\ninterstellar gas. We present a new method for uniformly decomposing HI spectral\nlines and estimating the properties of associated gas using the Autonomous\nGaussian Decomposition (AGD) algorithm. We find that Hi spectral lines recover\nphysical structures in the simulation with excellent completeness at high\nGalactic latitude, and this completeness declines with decreasing latitude due\nto strong velocity-blending of spectral lines. The temperature and column\ndensity inferred from our decomposition and radiative transfer method agree\nwith the simulated values within a factor of < 2 for the majority of gas\nstructures. We next compare synthetic spectra with observations from the\n21-SPONGE survey at the Karl G. Jansky Very Large Array using AGD. We find more\ncomponents per line of sight in 21-SPONGE than in synthetic spectra, which\nreflects insufficient simulated gas scale heights and the limitations of local\nbox simulations. In addition, we find a significant population of low-optical\ndepth, broad absorption components in the synthetic data which are not seen in\n21-SPONGE. This population is not obvious in integrated or per-channel\ndiagnostics, and reflects the benefit of studying velocity-resolved components.\nThe discrepant components correspond to the highest spin temperatures (1000 <\nTs < 4000 K), which are not seen in 21-SPONGE despite sufficient observational\nsensitivity. We demonstrate that our analysis method is a powerful tool for\ndiagnosing neutral ISM conditions, and future work is needed to improve\nobservational statistics and implementation of simulated physics." }, { "anchor": "High-mass star formation in Orion possibly triggered by cloud-cloud\n collision III, NGC2068 and NGC2071: Using the NANTEN2 Observatory, we carried out a molecular line study of\nhigh-mass star forming regions with reflection nebulae, NGC 2068 and NGC 2071,\nin Orion in the 13CO(J=2-1) transition. The 13CO distribution shows that there\nare two velocity components at 9.0 and 10.5 km/s . The blue-shifted component\nis in the northeast associated with NGC 2071, whereas the red-shifted component\nis in the southwest associated with NGC 2068. The total intensity distribution\nof the two clouds shows a gap of ~1 pc, suggesting that they are detached at\npresent. A detailed spatial comparison indicates that the two show\ncomplementary distributions. The blue-shifted component lies toward an\nintensity depression to the northwest of the red-shifted component, where we\nfind that a displacement of 0.8 pc makes the two clouds fit well with each\nother. Furthermore, a new simulation of non-frontal collisions shows that\nobservations from 60 degrees off the collisional axis agreed well with the\nvelocity structure in this region. On the basis of these results, we\nhypothesize that the two components collided with each other at a projected\nrelative velocity 3.0 km/s estimated to be 0.3 Myr for an assumed axis of the\nrelative motion 60 degrees off the line of sight. We assume that the two most\nmassive early B-type stars in the cloud, illuminating stars of the two\nreflection nebulae, were formed by collisional triggering at the interfaces\nbetween the two clouds. Given the other young high-mass star forming regions,\nnamely, M42, M43, and NGC 2024 (Fukui et al. 2018b; Ohama et al. 2017a), it\nseems possible that collisional triggering has been independently working to\nform O-type and early B-type stars in Orion in the last Myr over a projected\ndistance of ~80 pc.", "positive": "Intracluster light is already abundant at redshift beyond unity: Intracluster light (ICL) is diffuse light from stars that are gravitationally\nbound not to individual member galaxies, but to the halo of galaxy clusters.\nLeading theories predict that the ICL fraction, defined by the ratio of the ICL\nto the total light, rapidly decreases with increasing redshift, to the level of\na few per cent at z > 1. However, observational studies have remained\ninconclusive about the fraction beyond redshift unity because, to date, only\ntwo clusters in this redshift regime have been investigated. One shows a much\nlower fraction than the mean value at low redshift, whereas the other possesses\na fraction similar to the low-redshift value. Here we report an ICL study of\nten galaxy clusters at 1 \\lesssim z \\lesssim 2 based on deep infrared imaging\ndata. Contrary to the leading theories, our study finds that ICL is already\nabundant at z \\lesssim 1, with a mean ICL fraction of approximately 17\\%.\nMoreover, no significant correlation between cluster mass and ICL fraction or\nbetween ICL color and cluster-centric radius is observed. Our findings suggest\nthat gradual stripping can no longer be the dominant mechanism of ICL\nformation. Instead, our study supports the scenario wherein the dominant ICL\nproduction occurs in tandem with the formation and growth of the brightest\ncluster galaxies and/or through the accretion of preprocessed stray stars." }, { "anchor": "Unexpected Formation Modes of the First Hard Binary in Core Collapse: The conventional wisdom for the formation of the first hard binary in core\ncollapse is that three-body interactions of single stars form many soft\nbinaries, most of which are quickly destroyed, but eventually one of them\nsurvives. We report on direct N-body simulations to test these ideas, for the\nfirst time. We find that both assumptions are often incorrect: 1) quite a few\nthree-body interactions produce a hard binary from scratch; 2) and in many\ncases there are more than three bodies directly and simultaneously involved in\nthe production of the first binary. The main reason for the discrepancies is\nthat the core of a star cluster, at the first deep collapse, contains typically\nonly five or so stars. Therefore, the homogeneous background assumption, which\nstill would be reasonable for, say, 25 stars, utterly breaks down. There have\nbeen some speculations in this direction, but we demonstrate this result here\nexplicitly, for the first time.", "positive": "A Close Relationship between Lyman Alpha and Mg II in Green Pea Galaxies: The Mg II 2796,2803 doublet is often used to measure interstellar medium\nabsorption in galaxies, thereby serving as a diagnostic for feedback and\noutflows. However, the interpretation of Mg II remains confusing, due to\nresonant trapping and re-emission of the photons, analogous to Lyman Alpha.\nTherefore, in this paper, we present new MMT Blue Channel Spectrograph\nobservations of Mg II for a sample of 10 Green Pea galaxies at z~0.2-0.3, where\nLyman Alpha was previously observed with the Cosmic Origins Spectrograph on\nHubble Space Telescope. With strong, (mostly) double-peaked Lyman Alpha\nprofiles, these galaxies allow us to observe Mg II in the limit of low H I\ncolumn density. We find strong Mg II emission and little-to-no absorption. We\nuse photoionization models to show that nebular Mg II from H II regions is\nnon-negligible, and the ratios of Mg II/[OIII] 5007 vs. [OIII] 5007/[OII] 3727\nform a tight sequence. Using this relation, we predict intrinsic Mg II flux,\nand show that Mg II escape fractions range from 0 to 0.9. We find that the Mg\nII escape fraction correlates tightly with the Lyman Alpha escape fraction, and\nthe Mg II line profiles show evidence for broader and more redshifted emission\nwhen the escape fractions are low. These trends are expected if the escape\nfractions and velocity profiles of Lyman Alpha and Mg II are shaped by resonant\nscattering in the same low column density gas. As a consequence of a close\nrelation with Lyman Alpha, Mg II may serve as a useful diagnostic in the epoch\nof reionization, where Lyman Alpha and Lyman continuum photons are not easily\nobserved." }, { "anchor": "Intrinsic and observed dual AGN fractions from major mergers: A suite of 432 collisionless simulations of bound pairs of spiral galaxies\nwith mass ratios 1:1 and 3:1, and global properties consistent with the\n$\\Lambda$CDM paradigm, is used to test the conjecture that major mergers fuel\nthe dual AGN (DAGN) of the local volume. Our analysis is based on the premise\nthat the essential aspects of this scenario can be captured by replacing the\nphysics of the central BH with restrictions on their relative separation in\nphase space. We introduce several estimates of the DAGN fraction and infer\npredictions for the activity levels and resolution limits usually involved in\nsurveys of these systems, assessing their dependence on the parameters\ncontrolling the length of both mergers and nuclear activity. Given a set of\nconstraints, we find that the values adopted for some of the latter factors\noften condition the outcomes from individual experiments. Still, the results do\nnot reveal, in general, very tight correlations, being the tendency of the\nfrequencies normalized to the merger time to anticorrelate with the orbital\ncircularity the clearest effect. In agreement with other theoretical studies,\nour simulations predict intrinsic abundances of these systems that range from\n$\\sim$few to $15\\%$ depending on the maximum level of nuclear activity\nachieved. At the same time, we show that these probabilities are reduced by\nabout an order of magnitude when they are filtered with the typical constraints\napplied by observational studies of the DAGN fraction at low redshift. As a\nwhole, the results of the present work prove that the consideration of the most\ncommon limitations involved in the detection of close active pairs at optical\nwavelengths is sufficient by itself to reconcile the intrinsic frequencies\nenvisaged in a hierarchical universe with the small fractions of double-peaked\nnarrow-line systems which are often reported at kpc-scales.", "positive": "Multiscale mass transport in z~6 galactic discs: fueling black holes: By using AMR cosmological hydrodynamic N-body zoom-in simulations, with the\nRAMSES code, we studied the mass transport processes onto galactic nuclei from\nhigh redshift up to $z\\sim6$. Due to the large dynamical range of the\nsimulations we were able to study the mass accretion process on scales from\n$\\sim50[kpc]$ to $\\sim$ few $1[pc]$. We studied the BH growth on to the\ngalactic center in relation with the mass transport processes associated to\nboth the Reynolds stress and the gravitational stress on the disc. Such\nmethodology allowed us to identify the main mass transport process as a\nfunction of the scales of the problem. We found that in simulations that\ninclude radiative cooling and SNe feedback, the SMBH grows at the Eddington\nlimit for some periods of time presenting $\\langle f_{EDD}\\rangle\\approx 0.5$\nthroughout its evolution. The $\\alpha$ parameter is dominated by the Reynolds\nterm, $\\alpha_R$, with $\\alpha_R\\gg 1$. The gravitational part of the $\\alpha$\nparameter, $\\alpha_G$, has an increasing trend toward the galactic center at\nhigher redshifts, with values $\\alpha_G\\sim 1$ at radii <$\\sim$ few $ 10^1[pc]$\ncontributing to the BH fueling. In terms of torques, we also found that gravity\nhas an increasing contribution toward the galactic center at earlier epochs\nwith a mixed contribution above $\\sim 100 [pc]$. This complementary work\nbetween pressure gradients and gravitational potential gradients allows an\nefficient mass transport on the disc with average mass accretion rates of the\norder $\\sim$ few $1 [M_{\\odot}/yr]$. These level of SMBH accretion rates found\nin our cosmological simulations are needed in all models of SMBH growth that\nattempt to explain the formation of redshift $6-7$ quasars." }, { "anchor": "A deep learning approach to halo merger tree construction: A key ingredient for semi-analytic models (SAMs) of galaxy formation is the\nmass assembly history of haloes, encoded in a tree structure. The most commonly\nused method to construct halo merger histories is based on the outcomes of\nhigh-resolution, computationally intensive N-body simulations. We show that\nmachine learning (ML) techniques, in particular Generative Adversarial Networks\n(GANs), are a promising new tool to tackle this problem with a modest\ncomputational cost and retaining the best features of merger trees from\nsimulations. We train our GAN model with a limited sample of merger trees from\nthe Evolution and Assembly of GaLaxies and their Environments (EAGLE)\nsimulation suite, constructed using two halo finders-tree builder algorithms:\nSUBFIND-D-TREES and ROCKSTAR-ConsistentTrees. Our GAN model successfully learns\nto generate well-constructed merger tree structures with high temporal\nresolution, and to reproduce the statistical features of the sample of merger\ntrees used for training, when considering up to three variables in the training\nprocess. These inputs, whose representations are also learned by our GAN model,\nare mass of the halo progenitors and the final descendant, progenitor type\n(main halo or satellite) and distance of a progenitor to that in the main\nbranch. The inclusion of the latter two inputs greatly improves the final\nlearned representation of the halo mass growth history, especially for\nSUBFIND-like ML trees. When comparing equally sized samples of ML merger trees\nwith those of the EAGLE simulation, we find better agreement for SUBFIND-like\nML trees. Finally, our GAN-based framework can be utilised to construct merger\nhistories of low- and intermediate-mass haloes, the most abundant in\ncosmological simulations.", "positive": "A Proper Motions Study of the Globular Cluster M12 (NGC 6218): Using astrometric techniques developed by Anderson et al., we determine\nproper motions (PMs) in 14.60 arcmin X 16.53 arcmin area of the kinematically\n\"thick-disk\" globular cluster M12. The cluster's proximity and sparse nature\nmakes it a suitable target for ground-based telescopes. Archive images with\ntime gap of 11.1 years were observed with wide-field imager (WFI) mosaic camera\nmounted on ESO 2.2 m telescope. The median value of PM error in both components\nis 0.7 mas/yr for the stars having V less than or equal to 20 mag. PMs are used\nto determine membership probabilities and to separate field stars from the\ncluster sample. In electronic form, a membership catalog of 3725 stars with\nprecise coordinates, PMs, BVRI photometry is being provided. One of the\npossible applications of the catalog was shown by gathering the membership\ninformation of the variable stars, blue stragglers and X-ray sources reported\nearlier in the cluster's region." }, { "anchor": "Cosmic evolution of grain size distribution in galaxies using the\n $\u03bd^2$GC semi-analytic model: We investigate the cosmological evolution of interstellar dust with a\nsemi-analytical galaxy formation model ($\\nu^2$GC), focusing on the evolution\nof grain size distribution. The model predicts the statistical properties of\ndust mass and grain size distribution in galaxies across cosmic history. We\nconfirm that the model reproduces the relation between dust-to-gas ratio and\nmetallicity in the local Universe, and that the grain size distributions of the\nMilky Way (MW)-like sample become similar to the so-called MRN distribution\nthat reproduces the observed MW extinction curve. Our model, however, tends to\noverpredict the dust mass function at the massive end at redshift $z\\lesssim\n0.8$ while it reproduces the abundance of dusty galaxies at higher redshifts.\nWe also examine the correlation between grain size distribution and galaxy\nproperties (metallicity, specific star formation rate, gas fraction, and\nstellar mass), and observe a clear trend of large-grain-dominated,\nsmall-grain-dominated, and MRN-like grain size distributions from unevolved to\nevolved stages. As a consequence, the extinction curve shapes are flat, steep,\nand intermediate (MW-like) from the unevolved to evolved phases. At a fixed\nmetallicity, the grain size distribution tends to have larger fractions of\nsmall grains at lower redshift; accordingly, the extinction curve tends to be\nsteeper at lower redshift. We also predict that supersolar-metallicity objects\nat high redshift have flat extinction curves with weak 2175 \\AA bump strength.", "positive": "Isotopic ratios at z=0.68 from molecular absorption lines toward B\n 0218+357: Isotopic ratios of heavy elements are a key signature of the nucleosynthesis\nprocesses in stellar interiors. The contribution of successive generations of\nstars to the metal enrichment of the Universe is imprinted on the evolution of\nisotopic ratios over time. We investigate the isotopic ratios of carbon,\nnitrogen, oxygen, and sulfur through millimeter molecular absorption lines\narising in the z=0.68 absorber toward the blazar B 0218+357. We find that these\nratios differ from those observed in the Galactic interstellar medium, but are\nremarkably close to those in the only other source at intermediate redshift for\nwhich isotopic ratios have been measured to date, the z=0.89 absorber in front\nof PKS1830-211. The isotopic ratios in these two absorbers should reflect\nenrichment mostly from massive stars, and they are indeed close to the values\nobserved toward local starburst galaxies. Our measurements set constraints on\nnucleosynthesis and chemical evolution models." }, { "anchor": "The Sloan Digital Sky Survey Reverberation Mapping Project:\n Investigation of Continuum Lag Dependence on Broad-Line Contamination and\n Quasar Properties: This work studies the relationship between accretion-disk size and quasar\nproperties, using a sample of 95 quasars from the SDSS-RM project with measured\nlags between the $g$ and $i$ photometric bands. Our sample includes disk lags\nthat are both longer and shorter than predicted by the \\citet{SS73} model,\nrequiring explanations which satisfy both cases. Although our quasars each have\none lag measurement, we explore the wavelength-dependent effects of diffuse\nbroad line region (BLR) contamination through our sample's broad redshift\nrange, $0.1