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

We characterize the conditional distributions of the H I gas-to-stellar mass ratio, RHi≡MHi/M∗RHi≡MHi/M∗⁠, 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 RHiRHi conditional distributions combined with the Galaxy Stellar Mass Function to infer the bivariate MHiMHi 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 MHiMHi and M_* distributions presented here can be used to compare and constrain theoretical predictions as well as to generate galaxy mock catalogues.