We compile and carrefully homogenize local galaxy samples with available
information on stellar, HI and/or H2 masses, and morphology.
After processing the information on upper limits in the case of non gas
detections, we determine the HI- and H2-to-stellar mass
relations and their 1σ scatter for both late- and early-type galaxies.
The obtained relations are fitted to single or double power laws. Late-type
galaxies are significantly gas richer than early-type ones, specially at high
masses. The respective H2-to-HI mass ratios as a function of
M∗ are discussed. Further, we constrain the full mass-dependent
distribution functions of the HI- and H2-to-stellar mass ratios.
We find that they can be described by a Schechter function for late types and a
(broken) Schechter + uniform function for early types. By using the observed
galaxy stellar mass function and the volume-complete late-to-early-type galaxy
ratio as a function of M∗, these empirical distribution functions are
mapped into HI and H2 mass functions. The obtained mass
functions are consistent with those inferred from large surveys. The empirical
gas-to-stellar mass relations and their distributions for local late- and
early-type galaxies presented here can be used to constrain models and
simulations of galaxy evolution.Comment: 43 pages, 18 figures, to appear in RMxAA. Minor corrections
introduced. The presented results are optimal for comparisons with
theoretical predictions. Py-code to generate the HI- and H2-to-stellar mass
relations and their 1sigma scatter, as well as the full mass-dependent
distribution functions of the MHI/Ms and MH2/Ms ratios are available upon
request to A.R. Calett