2019ApJ...883....5B

We present a search for H I in the circumgalactic medium (CGM) of 21 massive (<logM_*>∼11.4), luminous red galaxies (LRGs) at z ∼ 0.5. Using UV spectroscopy of QSO sightlines projected within 500 kpc (∼R_vir) of these galaxies, we detect H I absorption in 11/21 sightlines, including two partial Lyman limit systems and two Lyman limit systems. The covering factor of logN(HI)≥ 16.0 gas within the virial radius of these LRGs is f_c(ρ≤ R_vir)=0.27_–0.10^+0.11, while for optically thick gas (logN(HI)≥ 17.2) it is f_c(ρ≤ R_vir)=0.15_–0.07^+0.10. Combining this sample of massive galaxies with previous galaxy-selected CGM studies, we find no strong dependence of the H I covering factor on galaxy mass, although star-forming galaxies show marginally higher covering factors. There is no evidence for a critical mass above which dense, cold (T ∼ 10⁴ K) gas is suppressed in the CGM of galaxies (spanning stellar masses 9.5≲logM_*≲11.8). The metallicity distribution in LRGs is indistinguishable from those found about lower-mass star-forming galaxies, and we find low-metallicity gas with [X/H]~-1.8 (1.5% solar) and below about massive galaxies. About half the cases show supersolar [Fe II/MgII] abundances as seen previously in cool gas near massive galaxies. While the high-metallicity cold gas seen in LRGs could plausibly result from condensation from a corona, the low-metallicity gas is inconsistent with this interpretation.