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

Abstract

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 \bar{z}=0.28 and {\bar{M}}_* ≈ {10}^10.1 {M}_⊙ . 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)≥slant {10}^13.5 {cm}}^-2. For each, we describe the measured clustering signal with a power-law correlation function ξ {(r)=(r/{r}₀)}^-γ and find that ({r}₀,γ )=(5.48+/- 0.07 {h}₁₀₀^-1 {Mpc},1.33+/- 0.04) for the auto-correlation and ({6.00}_-0.77^+1.09 {h}₁₀₀^-1 {Mpc},1.25+/- 0.18) for galaxy-O VI cross-correlation. We further estimate a bias factor of {b}_gg}=1.3+/- 0.1 from the galaxy-galaxy auto-correlation, indicating the galaxies are hosted by halos with mass {M}_halo}≈ {10}^{12.1+/- 0.05} {M}_⊙ . Finally, we estimate an O VI-galaxy bias factor {b}_{{O}{{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 {M}_halo}≈ {10}¹¹ {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.

Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 13033 and 11598. Partly based on observations taken at the MMT Observatory, a joint facility operated by the Smithsonian Institution and the University of Arizona.