1. Signatures of gas flows – I. Connecting the kinematics of the H i circumgalactic medium to galaxy rotation.
- Author
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Nateghi, Hasti, Kacprzak, Glenn G, Nielsen, Nikole M, Murphy, Michael T, Churchill, Christopher W, Muzahid, Sowgat, Sameer, and Charlton, Jane C
- Subjects
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ROTATION of galaxies , *GALACTIC evolution , *GAS flow , *SPACE telescopes , *KINEMATICS , *QUASARS - Abstract
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, |$f_{\rm EWcorot}$|. Using 70 quasar sightlines having Hubble Space Telescope /Cosmic Origins Spectrograph H i absorption (|${12\lt \log (N(\rm{{\rm H}\,{\small I}})/{\rm cm}^{-2})\lt 20}$|) within |$5R_{\rm vir}$| of |$z\lt 0.6$| galaxies we find that |$f_{\rm EWcorot}$| increases with increasing H i column density. |$f_{\rm EWcorot}$| is flat at |$\sim 0.6$| within |$R_{\rm vir}$| and decreases beyond |$R_{\rm vir}$| to |$f_{\rm EWcorot}$| |$\sim 0.35$|. |$f_{\rm EWcorot}$| 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 2 for edge-on galaxies. Inside |$R_{\rm vir}$| , co-rotation dominated H i is located within |$\sim 20$| 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 |$R_{\rm vir}$|. 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 |$_{\rm h}/{\rm M}_{\odot })\gt 12$| 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. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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