Dust as a tracer of gas in galaxies

摘要

We use a sample of 36 galaxies to study empirical relations between Herschel infrared (IR) luminosities and the total mass of the interstellar gas (H2 + HI). Such a comparison provides a simple empirical relationship without introducing the uncertainty of dust model fitting. We find tight correlations, and provide fits to these relations, between Herschel luminosities and the total gas mass integrated over entire galaxies, with the tightest, almost linear, correlation found for the longest wavelength data (SPIRE500). However, we find that accounting for the gas-phase metallicity (affecting the dust-to-gas ratio) is crucial when applying these relations to low-mass, and presumably high-redshift, galaxies. When examining these relations as a function of galactocentric radius, we find the same correlations, albeit with a larger scatter, up to radius of r ~ 0.7r_(25) (containing most of a galaxy's baryonic mass). The tight relations found for the bulk of the galaxy's baryonic content suggest that total gas masses of disk-like (non-merging/ULIRG) galaxies can be inferred from far-infrared continuum measurements in situations where only the latter are available. This work is to appear in Groves et al. (2014).