Signatures of gas flows - I. Connecting the kinematics of the H I circumgalactic medium to galaxy rotation

The circumgalactic medium (CGM) hosts many physical processes with different kinematic signatures that affect galaxy evolution. We address the CGM-galaxy kinematic connection by quantifying the fraction of H i that is aligned with galaxy rotation with the equivalent width co-rotation fraction, f(EWcorot). Using 70 quasar sightlines having Hubble Space Telescope/Cosmic Origins Spectrograph H i absorption (12<log(N(HI)/cm(-2))<20) within 5R(vir) of z<0.6 galaxies we find that f(EWcorot) increases with increasing H i column density. f(EWcorot) is flat at similar to 0.6 within Rvir and decreases beyond R-vir to f(EWcorot)similar to 0.35. f(EWcorot) also has a flat distribution with azimuthal and inclination angles within R-vir , but decreases by a factor of two outside of R-vir for minor axis gas and by a factor of 2 for edge-on galaxies. Inside R-vir , co-rotation dominated H i is located within similar to 20 deg of the major and minor axes. We surprisingly find equal amounts of H i absorption consistent with co-rotation along both major and minor axes within R-vir. However, this co-rotation disappears along the minor axis beyond R-vir, suggesting that if this gas is from outflows, then it is bound to galaxies. f(EWcorot) is constant over two decades of halo mass, with no decrease for log(M-h/M-circle dot)>12 as expected from simulations. Our results suggest that co-rotating gas flows are best found by searching for higher column density gas within R-vir and near the major and minor axes.