The Red Dead Redemption Survey of Circumgalactic Gas about Massive Galaxies. I. Mass and Metallicity of the Cool Phase

• Published in: The Astrophysical journal Vol. 883; no. 1; pp. 5 - 41
• Main Authors: Berg, Michelle A., Howk, J. Christopher, Lehner, Nicolas, Wotta, Christopher B., O'Meara, John M., Bowen, David V., Burchett, Joseph N., Peeples, Molly S., Tejos, Nicolas
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.09.2019; IOP Publishing
• Subjects: Astrophysics; Cold gas; Corona; Critical mass; Galaxies; galaxies: abundances; galaxies: evolution; galaxies: halos; Galaxy distribution; intergalactic medium; Metallicity; quasars: absorption lines; Spectroscopy; Star formation; Stars & galaxies
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/ab378e

We present a search for H i in the circumgalactic medium (CGM) of 21 massive ( ), luminous red galaxies (LRGs) at z ∼ 0.5. Using UV spectroscopy of QSO sightlines projected within 500 kpc (∼ ) 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 gas within the virial radius of these LRGs is , while for optically thick gas ( ) it is . 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 ). The metallicity distribution in LRGs is indistinguishable from those found about lower-mass star-forming galaxies, and we find low-metallicity gas with (1.5% solar) and below about massive galaxies. About half the cases show supersolar [Fe ii/ ] 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.