The Contribution of HI-Rich Galaxies to the Damped Absorber Population at z=0

Abstract

We present a study of HI-rich galaxies in the local universe selected from blind emission-line surveys. These galaxies represent the emission-line counterparts of local damped Lyman-alpha systems. We find that the HI cross-section of galaxies is drawn from a large range of galaxy masses below M_star, 66% of the area comes from galaxies in the range 8.5 < Log M_star < 9.7. Both because of the low mass galaxy contribution, and because of the range of galaxy types and luminosities at any given HI mass, the galaxies contributing to the HI cross-section are not exclusively L_star spirals, as is often expected. The optical and near infrared counterparts of these galaxies cover a range of types (from spirals to irregulars), luminosities (from L_star to <0.01 L_star), and surface brightnesses. The range of optical and near infrared properties as well as the kinematics for this population are consistent with the properties for the low-z damped Lyman-alpha absorbers. We also show that the number of HI-rich galaxies in the local universe does not preclude evolution of the low-z damped absorber population, but it is consistent with no evolution.