2018/10/31 by Joseph N. Burchett, Todd M. Tripp, J. Xavier Prochaska +14 · 1 citation
Physics and Astronomy · #Absorption (acoustics) #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Baryon #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Redshift #Solar mass #Spectral line #Virial theorem #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.3847/2041-8213/ab1f7f
Published in ApJL, Volume 877, Issue 2, Article L20
openalex publication_date 2019/05/24 · arxiv created 2019/06/09 · arxiv updated 2019/06/11 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
Abstract We survey the highly ionized circumgalactic media (CGM) of 29 blindly selected galaxies at based on high signal-to-noise ratio ultraviolet spectra of z ≳ 1 quasi-stellar objects and the galaxy database from the COS Absorption Survey of Baryon Harbors (CASBaH). We detect the Ne viii doublet in nine of the galaxies, and for gas with N ( ) ( ), we derive a covering fraction ( ) within impact parameters ρ ≤ 200 kpc of M * = 10 9.5–11.5 M ⊙ galaxies and ( ) within ρ ≤ 1.5 virial radii. We estimate the mass in -traced gas to be , or 6%–20% of the expected baryonic mass if the absorbers have solar metallicity. Ionizing Ne vii to requires 207 eV, and photons with this energy are scarce in the CGM. However, for the median halo mass and redshift of our sample, the virial temperature is close to the peak temperature for the ion, and the -bearing gas is plausibly collisionally ionized near this temperature. Moreover, we find that photoionized requires cool and low-density clouds that would be highly underpressured (by approximately two orders of magnitude) relative to the putative, ambient virialized medium, complicating scenarios where such clouds could survive. Thus, more complex (e.g., nonequilibrium) models may be required; this first statistical sample of absorber/galaxy systems will provide stringent constraints for future CGM studies.