Astrophys. J., 883, 5-5 (2019/September-3)
The red dead redemption survey of circumgalactic gas about massive galaxies. I. Mass and metallicity of the cool phase.
BERG M.A., HOWK J.C., LEHNER N., WOTTA C.B., O'MEARA J.M., BOWEN D.V., BURCHETT J.N., PEEPLES M.S. and TEJOS N.
Abstract (from CDS):
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 (∼Rvir) 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 fc(ρ≤ Rvir)=0.27–0.10+0.11, while for optically thick gas (logN(HI)≥ 17.2) it is fc(ρ≤ Rvir)=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.
© 2019. The American Astronomical Society. All rights reserved.
galaxies: abundances - galaxies: evolution - galaxies: halos - intergalactic medium - quasars: absorption lines
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