2010ApJ...710.1295O

We investigate the properties of H I-rich galaxies detected in blind radio surveys within the hierarchical structure formation scenario using a semianalytic model of galaxy formation. By drawing a detailed comparison between the properties of H I-selected galaxies and H I absorption systems, we argue a link between the local galaxy population and quasar absorption systems, particularly for damped Lyα absorption (DLA) systems and sub-DLA systems. First, we evaluate how many H I-selected galaxies exhibit H I column densities as high as those of DLA systems. We find that H I-selected galaxies with H I masses M_ H I_≳ 10⁸ M_☉have gaseous disks that produce H I column densities comparable to those of DLA systems. We conclude that DLA galaxies where the H I column densities are as high as those of DLA systems, contribute significantly to the population of H I-selected galaxies at M _ H I_≳ 10⁸ M_☉. Second, we find that star formation rates (SFRs) correlate tightly with H I masses (M_ H I_) rather than B- (and J-) band luminosities: SFR {vprop} M ^α_ H I_, α = 1.25-1.40 for 10⁶ ≤ M_ H I_/M☉_≤ 10¹¹. In the low-mass range M_H I_ ≲ 10⁸ M_☉, sub-DLA galaxies replace DLA galaxies as the dominant population. The number fraction of sub-DLA galaxies relative to galaxies reaches 40%-60% for M_ H I_∼ 10⁸ M_☉and 30%-80% for M_H I_∼ 10⁷ M_☉. The H I-selected galaxies at M_ H I_∼ 10⁷ M_☉ are a strong probe of sub-DLA systems that place stringent constraints on galaxy formation and evolution.