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 Lymanα absorption (DLA) systems (NHI 10 .3 cm−2 ) and sub-DLA systems (10 < NHI < 10 .3 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 10M . By contrast, in the low-mass range MHI 10M , sub-DLA galaxies replace DLA galaxies as the dominant population. The HI-selected galaxies would be a strong probe of DLA/sub-DLA systems.