Gas depletion in cluster galaxies depends strongly on their internal structure

We analyze galaxies in 300 nearby groups and clusters identified in the Sloan Digital Sky Survey using a photometric gas mass indicator that is useful for estimating the degree to which the interstellar medium of a cluster galaxy has been depleted. We study the radial dependence of inferred gas mass fractions for galaxies of different stellar masses and stellar surface densities. At fixed clustercentric distance and at fixed stellar mass, lower density galaxies are more strongly depleted of their gas than higher density galaxies. An analysis of depletion trends in the two-dimensional plane of stellar mass $M_*$ and stellar mass surface density $\mu_*$ reveals that gas depletion at fixed clustercentric radius is much more sensitive to the density of a galaxy than to its mass. We suggest that low density galaxies are more easily depleted of their gas, because they are more easily affected by ram-pressure and/or tidal forces. We also look at the dependence of our gas fraction/radius relations on the velocity dispersion of the cluster, finding no clear systematic trend.Comment: 9 pages, 8 figures, accepted for publication in MNRA

The Atomic to Molecular Transition and its Relation to the Scaling Properties of Galaxy Disks in the Local Universe

We extend existing semi-analytic models of galaxy formation to track atomic and molecular gas in disk galaxies. Simple recipes for processes such as cooling, star formation, supernova feedback, and chemical enrichment of the stars and gas are grafted on to dark matter halo merger trees derived from the Millennium Simulation. Each galactic disk is represented by a series of concentric rings. We assume that surface density profile of infalling gas in a dark matter halo is exponential, with scale radius r_d that is proportional to the virial radius of the halo times its spin parameter $\lambda$. As the dark matter haloes grow through mergers and accretion, disk galaxies assemble from the inside out. We include two simple prescriptions for molecular gas formation processes in our models: one is based on the analytic calculations by Krumholz, McKee & Tumlinson (2008), and the other is a prescription where the H_2 fraction is determined by the kinematic pressure of the ISM. Motivated by the observational results of Leroy et al. (2008), we adopt a star formation law in which $\Sigma_{SFR}\propto\Sigma_{H_2}$ in the regime where the molecular gas dominates the total gas surface density, and $\Sigma_{SFR}\propto \Sigma_{gas}^2$ where atomic hydrogen dominates. We then fit these models to the radial surface density profiles of stars, HI and H_2 drawn from recent high resolution surveys of stars and gas in nearby galaxies. We explore how the ratios of atomic gas, molecular gas and stellar mass vary as a function of global galaxy scale parameters, including stellar mass, stellar surface density, and gas surface density. We elucidate how the trends can be understood in terms of three variables that determine the partition of baryons in disks: the mass of the dark matter halo, the spin parameter of the halo, and the amount of gas recently accreted from the external environment.Comment: Made some minor changes according to the reviewer's suggestion. Accepted by MNRA

The clustering of galaxies as a function of their photometrically-estimated atomic gas content

We introduce a new photometric estimator of the HI mass fraction (M_HI/M_*) in local galaxies, which is a linear combination of four parameters: stellar mass, stellar surface mass density, NUV-r colour, and g-i colour gradient. It is calibrated using samples of nearby galaxies (0.025<z<0.05) with HI line detections from the GASS and ALFALFA surveys, and it is demonstrated to provide unbiased M_HI/M_* estimates even for HI-rich galaxies. We apply this estimator to a sample of ~24,000 galaxies from the SDSS/DR7 in the same redshift range. We then bin these galaxies by stellar mass and HI mass fraction and compute projected two point cross-correlation functions with respect to a reference galaxy sample. Results are compared with predictions from current semi-analytic models of galaxy formation. The agreement is good for galaxies with stellar masses larger than 10^10 M_sun, but not for lower mass systems. We then extend the analysis by studying the bias in the clustering of HI-poor or HI-rich galaxies with respect to galaxies with normal HI content on scales between 100 kpc and ~5 Mpc. For the HI-deficient population, the strongest bias effects arise when the HI-deficiency is defined in comparison to galaxies of the same stellar mass and size. This is not reproduced by the semi-analytic models, where the quenching of star formation in satellites occurs by "starvation" and does not depend on their internal structure. HI-rich galaxies with masses greater than 10^10 M_sun are found to be anti-biased compared to galaxies with "normal" HI content. Interestingly, no such effect is found for lower mass galaxies.Comment: 14 pages, 10 figures, accepted for publication in MNRAS, slightly revised in the tex

COLD GASS, an IRAM Legacy Survey of Molecular Gas in Massive Galaxies: III. Comparison with semi-analytic models of galaxy formation

We compare the semi-analytic models of galaxy formation of Fu et al. (2010), which track the evolution of the radial profiles of atomic and molecular gas in galaxies, with gas fraction scaling relations derived from the COLD GASS survey (Saintonge et al 2011). The models provide a good description of how condensed baryons in galaxies with gas are partitioned into stars, atomic and molecular gas as a function of galaxy stellar mass and surface density. The models do not reproduce the tight observed relation between stellar surface density and bulge-to-disk ratio for this population. We then turn to an analysis of the"quenched" population of galaxies without detectable cold gas. The current implementation of radio-mode feedback in the models disagrees strongly with the data. In the models, gas cooling shuts down in nearly all galaxies in dark matter halos above a mass of 10**12 M_sun. As a result, stellar mass is the observable that best predicts whether a galaxy has little or no neutral gas. In contrast, our data show that quenching is largely independent of stellar mass. Instead, there are clear thresholds in bulge-to-disk ratio and in stellar surface density that demarcate the location of quenched galaxies. We propose that processes associated with bulge formation play a key role in depleting the neutral gas in galaxies and that further gas accretion is suppressed following the formation of the bulge, even in dark matter halos of low mass.Comment: 12 figures, accepted for publication in MNRAS, the COLD GASS data is available at http://www.mpa-garching.mpg.de/COLD_GASS/data.shtm

A study of the HI gas fractions of galaxies at z ~ 1

Due to the fact that HI mass measurements are not available for large galaxy samples at high redshifts, we apply a photometric estimator of the HI-to-stellar mass ratio (M_HI/M_*) calibrated using a local Universe sample of galaxies to a sample of galaxies at z ~ 1 in the DEEP2 survey. We use these HI mass estimates to calculate HI mass functions (HIMFs) and cosmic HI mass densities (Omega_HI), and to examine the correlation between star formation rate and HI gas content, for galaxies at z ~ 1. We have estimated HI gas masses for ~ 7,000 galaxies in the DEEP2 survey with redshifts in the range 0.75 < z < 1.4 and stellar masses M_* > 10^{10} M_solar, using a combination of the rest-frame ultraviolet-optical colour (NUV - r) and stellar mass density (mu_*) as a way to estimate M_HI/M_*. It is found that the high mass end of high-z HI mass function (HIMF) is quite similar to that of the local HIMF. The lower limit of Omega_HI,limit = 2.1 * 10^{-4} h_70^{-1}, obtained by directly integrating the HI mass of galaxies with M_* > 10^{10} M_solar, confirms that massive star-forming galaxies do not dominate the neutral gas at z ~ 1. We study the evolution of the HI mass to stellar mass ratio from z ~ 1 to today and find a steeper relation between HI gas mass fraction and stellar mass at higher redshifts. Specifically, galaxies with M_* = 10^{11} M_solar at z ~ 1 are found to have 3 - 4 times higher neutral gas fractions than local galaxies, while the increase is as high as 4 - 12 times at M_* = 10^{10} M_solar. The quantity M_HI/SFR exhibits very large scatter, and the scatter increases from a factor of 5 - 7 at z = 0 to factors close to a hundred at z = 1. This implies that there is no relation between HI gas and star formation in high redshift galaxies. The HI gas must be linked to cosmological gas accretion processes at high redshifts.Comment: 10 pages, 13 figures, A&A accepte

An observational and theoretical view of the radial distribution of HI gas in galaxies

We analyze the radial distribution of HI gas for 23 disk galaxies with unusually high HI content from the Bluedisk sample, along with a similar-sized sample of "normal" galaxies. We propose an empirical model to fit the radial profile of the HI surface density, an exponential function with a depression near the center. The radial HI surface density profiles are very homogeneous in the outer regions of the galaxy; the exponentially declining part of the profile has a scale-length of $\sim 0.18$ R1, where R1 is the radius where the column density of the HI is 1 M$_{\odot}$ pc$^{-2}$. This holds for all galaxies, independent of their stellar or HI mass. The homogenous outer profiles, combined with the limited range in HI surface density in the non-exponential inner disk, results in the well-known tight relation between HI size and HI mass. By comparing the radial profiles of the HI-rich galaxies with those of the control systems, we deduce that in about half the galaxies, most of the excess gas lies outside the stellar disk, in the exponentially declining outer regions of the HI disk. In the other half, the excess is more centrally peaked. We compare our results with existing smoothed-particle hydrodynamical simulations and semi-analytic models of disk galaxy formation in a $\Lambda$ Cold Dark Matter universe. Both the hydro simulations and the semi-analytic models reproduce the HI surface density profiles and the HI size-mass relation without further tuning of the simulation and model inputs. In the semi-analytic models, the universal shape of the outer HI radial profiles is a consequence of the {\em assumption} that infalling gas is always distributed exponentially. The conversion of atomic gas to molecular form explains the limited range of HI surface densities in the inner disk. These two factors produce the tight HI mass-size relation.Comment: 15 pages, 14 figures, submitted to MNRA

The atomic-to-molecular transition and its relation to the scaling properties of galaxy discs in the local Universe

We extend the existing semi-analytic models of galaxy formation to track atomic and molecular gas in disc galaxies. Simple recipes for processes such as cooling, star formation, supernova feedback and chemical enrichment of the stars and gas are grafted on to dark matter halo merger trees derived from the Millennium Simulation. Each galactic disc is represented by a series of concentric rings. We assume that the surface density profile of an infalling gas in a dark matter halo is exponential, with scale radius rd that is proportional to the virial radius of the halo times its spin parameter λ. As the dark matter haloes grow through mergers and accretion, disc galaxies assemble from the inside out. We include two simple prescriptions for molecular gas formation processes in our models: one is based on the analytic calculations by Krumholz, McKee & Tumlinson, and the other is a prescription where the H2 fraction is determined by the pressure of the interstellar medium (ISM). Motivated by the observational results of Leroy et al., we adopt a star formation law in which forumla in the regime where the molecular gas dominates the total gas surface density, and forumla where atomic hydrogen dominates. We then fit these models to the radial surface density profiles of stars, H I and H2 drawn from recent high-resolution surveys of stars and gas in nearby galaxies. We explore how the ratios of atomic gas, molecular gas and stellar mass vary as a function of global galaxy scale parameters, including stellar mass, stellar surface density and gas surface density. We elucidate how the trends can be understood in terms of three variables that determine the partition of baryons in discs: the mass of the dark matter halo, the spin parameter of the halo and the amount of gas recently accreted from the external environment.Jian Fu thanks the Joint Program between Chinese Academic of Sciences and Max-Planck-Gesellschaft for the chance of visiting the Max-Planck-Institut fur Astrophysik, and Deutsche Forschungs- ¨ gemeinschaft for the extra support. He also thanks the support from the National Science Foundation of the Key Project No. 10833005, the Group Innovation Project No. 10821302, and by 973 programme No. 2007CB815402. Guinevere Kauffmann thanks Reinhard Genzel for conversations that inspired this work. Mark Krumholz acknowledges support from the Alfred P. Sloan Foundation, the National Science Foundation through grant AST-0807739, NASA through ATFP grant NNX09AK31G and NASA through the Spitzer Space Telescope Theoretical Research Program, provided by a contract issued by the Jet Propulsion Laboratory

L-galaxies 2020: Spatially resolved cold gas phases, star formation and chemical enrichment in galactic discs

© 2023 Oxford University Press. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1093/mnras/stz3233We have updated the Munich galaxy formation model, L-Galaxies, to follow the radial distributions of stars and atomic and molecular gas in galaxy discs. We include an H2-based star-formation law, as well as a detailed chemical-enrichment model with explicit mass-dependent delay times for SN-II, SN-Ia and AGB stars. Information about the star formation, feedback and chemical-enrichment histories of discs is stored in 12 concentric rings. The new model retains the success of its predecessor in reproducing the observed evolution of the galaxy population, in particular, stellar mass functions and passive fractions over the redshift range 0Peer reviewe

Galaxy formation in the Planck cosmology - I. Matching the observed evolution of star formation rates, colours and stellar masses

We have updated the Munich galaxy formation model to the Planck first-year cosmology, while modifying the treatment of baryonic processes to reproduce recent data on the abundance and passive fractions of galaxies from z = 3 down to z = 0. Matching these more extensive and more precise observational results requires us to delay the reincorporation of wind ejecta, to lower the surface density threshold for turning cold gas into stars, to eliminate ram-pressure stripping in haloes less massive than ∼1014 M⊙, and to modify our model for radio mode feedback. These changes cure the most obvious failings of our previous models, namely the overly early formation of low-mass galaxies and the overly large fraction of them that are passive at late times. The new model is calibrated to reproduce the observed evolution both of the stellar mass function and of the distribution of star formation rate at each stellar mass. Massive galaxies (log M⋆/M⊙ ≥ 11.0) assemble most of their mass before z = 1 and are predominantly old and passive at z = 0, while lower mass galaxies assemble later and, for log M⋆/M⊙ ≤ 9.5, are still predominantly blue and star forming at z = 0. This phenomenological but physically based model allows the observations to be interpreted in terms of the efficiency of the various processes that control the formation and evolution of galaxies as a function of their stellar mass, gas content, environment and time

The GALEX Arecibo SDSS Survey. VI. Second Data Release and Updated Gas Fraction Scaling Relations

We present the second data release from the GALEX Arecibo SDSS Survey (GASS), an ongoing large Arecibo program to measure the HI properties for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025<z<0.05. GASS targets are selected from the Sloan Digital Sky Survey (SDSS) spectroscopic and Galaxy Evolution Explorer (GALEX) imaging surveys, and are observed until detected or until a gas mass fraction limit of a few per cent is reached. This second data installment includes new Arecibo observations of 240 galaxies, and marks the 50% of the complete survey. We present catalogs of the HI, optical and ultraviolet parameters for these galaxies, and their HI-line profiles. Having more than doubled the size of the sample since the first data release, we also revisit the main scaling relations of the HI mass fraction with galaxy stellar mass, stellar mass surface density, concentration index, and NUV-r color, as well as the gas fraction plane introduced in our earlier work.Comment: 30 pages, 12 figures. Accepted for publication in A&A. Version with complete Appendix A available at http://www.mpa-garching.mpg.de/GASS/pubs.php . GASS released data can be found at http://www.mpa-garching.mpg.de/GASS/data.ph