The ESO UVES advanced data products quasar sample: II. Cosmological evolution of the neutral gas mass density

Damped absorbers, seen in the spectra of background quasars, are unique probes to select Hi-rich galaxies. These galaxies allow one to estimate the neutral gas mass over cosmological scales. The neutral gas mass is a possible indicator of gas consumption as star formation proceeds. The damped Ly alpha absorbers and sub-DLAs are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we presented the results of a search for DLAs and sub-DLAs in the European Southern Observatory (ESO) Ultraviolet Visual Echelle Spectrograph (UVES) advanced data products dataset of 250 quasars. The complete sample shows that sub-DLAs contribute 8-20% to the total omega g from 1.5 [lessthan] [zeta] [lessthan] 5.0. In agreement with previous studies, no evolution of omega g was observed from low to high redshift, suggesting that star formation alone cannot explain this non-evolution and replenishment of gas and that recombination of ionized gas is needed.