The H i and stellar mass bivariate distribution of centrals and satellites for all, late-, and early-type local galaxies

Abstract

ABSTRACT We characterize the conditional distributions of the H i gas-to-stellar mass ratio, $\mbox{$R_{\rm H\,\rm{i}}$}\equiv \mbox{$M_{\rm H\,\rm{i}}$}/\mbox{$M_{\ast }$}$, given the stellar mass, M*, of local galaxies from M* ∼ 107–1012 M⊙ separated into centrals and satellites as well as into late- and early-type galaxies (LTGs and ETGs, respectively). To do so, we use (1) the homogeneous ‘eXtended GALEX Arecibo SDSS Survey’, xGASS (Catinella et al. 2018), by re-estimating their upper limits and taking into account them in our statistical analysis; and (2) the results from a large compilation of H i data reported in Calette et al. (2018). We use the $R_{\rm H\,\rm{i}}$ conditional distributions combined with the Galaxy Stellar Mass Function to infer the bivariate $M_{\rm H\,\rm{i}}$ and M* distribution of all galaxies as well of the late/early-type and central/satellite subsamples and their combinations. Satellites are on average less H i gas-rich than centrals at low and intermediate masses, with differences being larger for ETGs than LTGs; at M* > 3−5 × 1010 M⊙ the differences are negligible. The differences in the H i gas content are much larger between LTGs and ETGs than between centrals and satellites. Our empirical H i Mass Function is strongly dominated by central galaxies at all masses. The empirically constrained bivariate $M_{\rm H\,\rm{i}}$ and M* distributions presented here can be used to compare and constrain theoretical predictions as well as to generate galaxy mock catalogues.