The CGM2 Survey: Quenching and the Transformation of the Circumgalactic Medium

Kirill Tchernyshyov, Jessica K. Werk, Matthew C. Wilde, J. Xavier Prochaska, Todd M. Tripp, Joseph N. Burchett, Rongmon Bordoloi, J. Christopher Howk, Nicolas Lehner, John M. O’Meara, Nicolas Tejos, Jason Tumlinson

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This study addresses how the incidence rate of strong O vi absorbers in a galaxy’s circumgalactic medium (CGM) depends on galaxy mass and, independently, on the amount of star formation in the galaxy. We use Hubble Space Telescope/Cosmic Origins Spectrograph absorption spectroscopy of quasars to measure O vi absorption within 400 projected kpc and 300 km s−1 of 52 galaxies with M * ∼ 3 × 1010 M . The galaxies have redshifts 0.12 < z < 0.6, stellar masses 1010.1 M < M * < 1010.9 M , and spectroscopic classifications as star-forming or passive. We compare the incidence rates of high column density O vi absorption (N O VI ≥ 1014.3 cm−2) near star-forming and passive galaxies in two narrow ranges of stellar mass and, separately, in a matched range of halo mass. In all three mass ranges, the O vi covering fraction within 150 kpc is higher around star-forming galaxies than around passive galaxies with greater than 3σ-equivalent statistical significance. On average, the CGM of star-forming galaxies with M * ∼ 3 × 1010 M contains more O vi than the CGM of passive galaxies with the same mass. This difference is evidence for a CGM transformation that happens together with galaxy quenching and is not driven primarily by halo mass.

Original languageEnglish
Article number41
JournalAstrophysical Journal
Issue number2
StatePublished - 1 Jun 2023


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