The COS Absorption Survey of Baryon Harbors: The Galaxy Database and Cross-correlation Analysis of O vi Systems
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 and . 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 . For each, we describe the measured clustering signal with a power-law correlation function and find that for the auto-correlation and for galaxy–O vi cross-correlation. We further estimate a bias factor of from the galaxy–galaxy auto-correlation, indicating the galaxies are hosted by halos with mass . Finally, we estimate an O vi–galaxy bias factor from the cross-correlation which is consistent with O vi absorbers being hosted by dark matter halos with typical mass . 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.