2023/11/09 by Nateghi, Hasti, Kacprzak, Glenn G., Nielsen, Nikole M. +5 · 1 citation
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2311.05164
The 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 HI that is aligned with galaxy rotation with the equivalent width co-rotation fraction, f\rm EWcorot. Using 70 quasar sightlines having HST/COS HI absorption (12<log (N(HI)/\rm cm-2)<20) within 5R\rm vir of z<0.6 galaxies we find that f\rm EWcorot increases with increasing HI column density. f\rm EWcorot is flat at ∼0.6 within R\rm vir and decreases beyond R\rm vir to f\rm EWcorot∼0.35. f\rm EWcorot also has a flat distribution with azimuthal and inclination angles within R\rm vir, but decreases by a factor of two outside of R\rm vir for minor axis gas and by a factor of two for edge-on galaxies. Inside R\rm vir, co-rotation dominated HI is located within ∼ 20 deg of the major and minor axes. We surprisingly find equal amounts of HI absorption consistent with co-rotation along both major and minor axes within R\rm vir. However, this co-rotation disappears along the minor axis beyond R\rm vir, suggesting that if this gas is from outflows, then it is bound to galaxies. f\rm EWcorot is constant over two decades of halo mass, with no decrease for log(M\rm h/M\odot)>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\rm vir and near the major and minor axes.