Variation of galactic cold gas reservoirs with stellar mass

Abstract

The stellar and neutral hydrogen (H i) mass functions at z ∼ 0 are fundamental benchmarks for current models of galaxy evolution. A natural extension of these benchmarks is the two-dimensional distribution of galaxies in the plane spanned by stellar and H i mass, which provides a more stringent test of simulations, as it requires the H i to be located in galaxies of the correct stellar mass. Combining H i data from the ALFALFA survey, with optical data from SDSS, we find a distinct envelope in the H i-to-stellar mass distribution, corresponding to an upper limit in the H i fraction that varies monotonically over five orders of magnitude in stellar mass. This upper envelope in H i fraction does not favour the existence of a significant population of dark galaxies with large amounts of gas but no corresponding stellar population. The envelope shows a break at a stellar mass of ∼ 10 9 M ⊙ , which is not reproduced by modern models of galaxy populations tracing both stellar and gas masses. The discrepancy between observations and models suggests a mass dependence in gas storage and consumption missing in current galaxy evolution prescriptions. The break coincides with the transition from galaxies with predominantly irregular morphology at low masses to regular disks at high masses, as well as the transition from cold to hot accretion of gas in simulations.

The AMIGA sample of isolated galaxies

“…Catinella et al 2010;Huang et al 2012;Maddox et al 2015), however, our relations do not appear to show evidence of any break.…”

“…Using the HI-selected population of ALFALFA, Huang et al (2012) found that the scaling relation between stellar mass and HI mass has a slope change at a stellar mass of about 10 9 M , and this result was confirmed in Maddox et al (2015) via a similar analysis of the ALFALFA dataset. The fact that such a break in the scaling relation is not apparent in our dataset does not indicate a conflict with these results because the break is expected to occur at M * ∼ 10 9 M and our dataset begins at L B ∼ 10 9 L (although stellar mass and B-band luminosity are not directly equivalent they should be the same order of magnitude).…”

Towards a consistent model for both the H i and stellar mass functions of galaxies

“…In this work we perform a crude selection on the semi-analytic galaxies, converting the HI mass to a HI flux by setting an observer at the centre of the simulation box. We see from the top panel of Figure 5 that our model galaxies span the same range of stellar mass as the ALFALFA data and show the same upper limit in gas fraction (Maddox et al 2015). However, the median ratio is offset significantly from that observed by AL-FALFA.…”

The impact of galactic properties and environment on the quenching of central and satellite galaxies: a comparison between SDSS, Illustris and L-Galaxies

“…Given that disk mass and D/T (= 1 -B/T ) correlates with gas mass and gas fraction (e.g., Saintonge et al 2011;Maddox et al 2015), it is likely that these variables give information on what remains to be quenched in a given galaxy, and hence how much work must be done to quench it. Alternatively, central velocity dispersion (which is known to correlate strongly with dynamically measured MBH ) likely gives information regarding the available energy to do work quenching the system.…”