The COS Absorption Survey of Baryon Harbors: The Galaxy Database and Cross-correlation Analysis of O vi Systems

J. Xavier Prochaska, Joseph N. Burchett, Todd M. Tripp, Jessica K. Werk, Christopher N.A. Willmer, J. Christopher Howk, Scott Lange, Nicolas Tejos, Joseph D. Meiring, Jason Tumlinson, Nicolas Lehner, Amanda B. Ford, Romeel Davé

Research output: Contribution to journalReview articlepeer-review

22 Scopus citations


We describe the survey for galaxies in the fields surrounding nine sightlines to far-UV bright, z ∼ 1 quasars that define the COS Absorption Survey of Baryon Harbors (CASBaH) program. The photometry and spectroscopy that comprise the data set come from a mixture of public surveys (SDSS, DECaLS) and our dedicated efforts on private facilities (Keck, MMT, LBT). We report the redshifts and stellar masses for 5902 galaxies within ≈10 comoving-Mpc of the sightlines with a median of z̄ = 0.28 and M̄ 1010.1M. This data set, publicly available as the CASBaH specDB, forms the basis of several recent and ongoing CASBaH analyses. Here, we perform a clustering analysis of the galaxy sample with itself (auto-correlation) and against the set of O vi absorption systems (cross-correlation) discovered in the CASBaH quasar spectra with column densities N(O+5) 1013.5 cm-2. For each, we describe the measured clustering signal with a power-law correlation function σ (r) = (r/r0) and find that (r0, γ )=(5.48\pm 0.07 h100 -1 Mpc, 1.33 ± 0.04) for the auto-correlation and (6.00-0.77 +1.09 h100 -1 Mpc 1.25 ± 0.18) for galaxy-O vi cross-correlation. We further estimate a bias factor of bgg =1.3 ± 0.1 from the galaxy-galaxy auto-correlation, indicating the galaxies are hosted by halos with mass Mhalo ≈ 1012.1 ± 0.05 M. Finally, we estimate an O vi-galaxy bias factor bO VI = 1.0 ± 0.1 from the cross-correlation which is consistent with O vi absorbers being hosted by dark matter halos with typical mass Mhalo ≈ 1011 M. Future works with upcoming data sets (e.g., CGM2) will improve upon these results and will assess whether any of the detected O vi arises in the intergalactic medium.

Original languageEnglish (US)
Article number24
JournalAstrophysical Journal, Supplement Series
Issue number2
StatePublished - 2019


  • astronomical databases: miscellaneous
  • galaxies: evolution
  • intergalactic medium
  • quasars: absorption lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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