We investigate the origin of intervening cool absorption detected in the spectra of background quasars and the nature of associated galaxies across a broad redshift range of zabsmin łe z łe and a largely unexplored galactrocentric distance of łesssim 20 kpc. Using nebular emission lines identified in DESI fibre spectra centred on quasars, we detect galaxies at a typical detection rate of ∼ at z łesssim 1, which increases with the equivalent width (A significant fraction () łe łogsfrmax, located at projected galactocentric distances of of these galaxies are associated with strong absorbers with ge 2 Å. These absorbers trace galaxies spanning stellar masses of ̊m łe łog (M_⋆/M_⊙) łe and star formation rates (SFRs) of ̊m łogsfrmin łe łog (SFR M_⊙yr^ -1 kpc. We find that the average absorber strength increases from Å to Å between redshifts of z ∼ and indicating evolution in the cool gas content of galaxy halos. The relatively constant absorber strength with galactocentric distance implies a clumpy structure of cool gas in the circumgalactic medium (CGM). Further, we find a positive correlation between versus stellar mass (̊m M_⋆), and the SFR, suggesting that the distribution of metal-enriched cool gas in the CGM is closely tied to the properties of the host galaxies. The redshift evolution of gas-phase metallicity suggests that strong absorbers trace the general population of star-forming galaxies. The velocity dispersion of the cool gas increases with halo mass, and the wide range of the line-of-sight velocity offset (to ̨ms) between the galaxy systemic velocity and absorbers highlights the dynamical nature of CGM. However, the majority of this gas remains gravitationally bound to the dark matter halos, consistent with a picture of gas recycling via galactic fountains.
Chaudhary et al. (Wed,) studied this question.