Kinematics of the O vi Circumgalactic Medium: Halo Mass Dependence and Outflow Signatures

We probe the high-ionization circumgalactic medium by examining absorber kinematics, absorber?galaxy kinematics, and average absorption profiles of 31 O vi absorbers from the ?Multiphase Galaxy Halos? Survey as a function of halo mass, redshift, inclination, and azimuthal angle. The galaxies are isolated at 0.12;z(gal);D;;200 kpc. Each absorber?galaxy pair has Hubble Space Telescope images and COS quasar spectra, and most galaxy redshifts have been accurately measured from Keck/ESI spectra. Using the pixel-velocity two-point correlation function (TPCF) method, we find that O vi absorber kinematics have a strong halo mass dependence. Absorbers hosted by ?L* galaxies have the largest velocity dispersions, which we interpret to be that the halo virial temperature closely matches the temperature at which the collisionally ionized O vi fraction peaks. Lower-mass galaxies and group environments have smaller velocity dispersions. Total column densities follow the same behavior, consistent with theoretical findings. After normalizing out the observed mass dependence, we studied absorber?galaxy kinematics with a modified TPCF and found nonvirialized motions due to outflowing gas. Edge-on minor-axis gas has large optical depths concentrated near the galaxy systemic velocity as expected for bipolar outflows, while face-on minor-axis gas has a smoothly decreasing optical depth distribution out to large normalized absorber?galaxy velocities, suggestive of decelerating outflowing gas. Accreting gas signatures are not observed owing to ?kinematic blurring,? in which multiple line-of-sight structures are observed. These results indicate that galaxy mass dominates O vi properties over baryon cycle processes.