Kinematics of Circumgalactic Gas: Feeding Galaxies and Feedback. (arXiv:1901.09123v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Martin_C/0/1/0/all/0/1">Crystal L. Martin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ho_S/0/1/0/all/0/1">Stephanie H. Ho</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kacprzak_G/0/1/0/all/0/1">Glenn G. Kacprzak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Churchill_C/0/1/0/all/0/1">Christopher W. Churchill</a>
We present observations of 50 pairs of redshift z ~ 0.2 star-forming galaxies
and background quasars. These sightlines probe the circumgalactic medium (CGM)
out to half the virial radius, and we describe the circumgalactic gas
kinematics relative to the reference frame defined by the galactic disks. We
detect halo gas in MgII absorption, measure the equivalent-width-weighted
Doppler shifts relative to each galaxy, and find that the CGM has a component
of angular momentum that is aligned with the galactic disk. No net
counter-rotation of the CGM is detected within 45 degrees of the major axis at
any impact parameter. The velocity offset of the circumgalactic gas correlates
with the projected rotation speed in the disk plane out to disk radii of
roughly 70 kpc. We confirm previous claims that the MgII absorption becomes
stronger near the galactic minor axis and show that the equivalent width
correlates with the velocity range of the absorption. We cannot directly
measure the location of any absorber along the sightline, but we explore the
hypothesis that individual velocity components can be associated with gas
orbiting in the disk plane or flowing radially outward in a conical outflow. We
conclude that centrifugal forces partially support the low-ionization gas and
galactic outflows kinematically disturb the CGM producing excess absorption.
Our results firmly rule out schema for the inner CGM that lack rotation and
suggest that angular momentum as well as galactic winds should be included in
any viable model for the low-redshift CGM.
We present observations of 50 pairs of redshift z ~ 0.2 star-forming galaxies
and background quasars. These sightlines probe the circumgalactic medium (CGM)
out to half the virial radius, and we describe the circumgalactic gas
kinematics relative to the reference frame defined by the galactic disks. We
detect halo gas in MgII absorption, measure the equivalent-width-weighted
Doppler shifts relative to each galaxy, and find that the CGM has a component
of angular momentum that is aligned with the galactic disk. No net
counter-rotation of the CGM is detected within 45 degrees of the major axis at
any impact parameter. The velocity offset of the circumgalactic gas correlates
with the projected rotation speed in the disk plane out to disk radii of
roughly 70 kpc. We confirm previous claims that the MgII absorption becomes
stronger near the galactic minor axis and show that the equivalent width
correlates with the velocity range of the absorption. We cannot directly
measure the location of any absorber along the sightline, but we explore the
hypothesis that individual velocity components can be associated with gas
orbiting in the disk plane or flowing radially outward in a conical outflow. We
conclude that centrifugal forces partially support the low-ionization gas and
galactic outflows kinematically disturb the CGM producing excess absorption.
Our results firmly rule out schema for the inner CGM that lack rotation and
suggest that angular momentum as well as galactic winds should be included in
any viable model for the low-redshift CGM.
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