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

Abstract

We describe the survey for galaxies in the fields surrounding nine sightlines to far-UV bright, z similar to 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 approximate to 10 comoving-Mpc of the sightlines with a median of (z) over bar = 0.28 and (M) over bar (*) approximate to 10(10.1) M-circle dot. 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) >= 10(13.5) cm(-2). For each, we describe the measured clustering signal with a power-law correlation function xi(r) = (r/r(0))(-gamma) and find that (r(0), gamma) = (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 approximate to 10(12.1 +/- 0.05) M-circle dot. 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 approximate to 10(11) M-circle dot. Future works with upcoming data sets (e.g., CGM(2)) will improve upon these results and will assess whether any of the detected O VI arises in the intergalactic medium.