HI-selected Galaxies As a Probe of Quasar Absorption Systems

We investigate the properties of local HI-selected galaxies detected in blind radio surveys by using semi-analytic galaxy formation models in the hierarchical structure formation scenario. By drawing a detailed comparison between the properties of the HI-selected galaxies and the quasar absorption systems, we investigate a link between the local galaxy population and the quasar absorption systems, particularly for Damped Lymana absorption (DLA) systems (Nhi > 1020ʹ3 cm"2) and sub-DLA systems (1019 < Nhi < 1020ʹ3 cm"2).We find that DLA galaxies, in which the HI column densities are as high as those of DLA systems, contribute primarily to the population of local HI-selected galaxies at MHI ^ 108 M©. By contrast, in the low-mass range MHI < 107M©, sub-DLA galaxies replace DLA galaxies as the dominant population. The HI-selected galaxies would be a strong probe of DLA/sub-DLA systems.