Halo Gas and Galaxy Disk Kinematics Derived from Observations and LCDM
  Simulations of MgII Absorption Selected Galaxies at Intermediate Redshift
  We obtained ESI/Keck rotation curves of 10 MgII absorption selected galaxies
(0.3 < z < 1.0) for which we have WFPC-2/HST images and high resolution
HIRES/Keck and UVES/VLT quasar spectra of the MgII absorption profiles. We
perform a kinematic comparison of these galaxies and their associated halo MgII
absorption. For all 10 galaxies, the majority of the absorption velocities lie
in the range of the observed galaxy rotation velocities. In 7/10 cases, the
absorption velocities reside fully to one side of the galaxy systemic velocity
and usually align with one arm of the rotation curve. In all cases, a constant
rotating thick-disk model poorly reproduces the full spread of observed MgII
absorption velocities when reasonably realistic parameters are employed. In
2/10 cases, the galaxy kinematics, star formation surface densities, and
absorption kinematics have a resemblance to those of high redshift galaxies
showing strong outflows. We find that MgII absorption velocity spread and
optical depth distribution may be dependent on galaxy inclination. To further
aid in the spatial-kinematic relationships of the data, we apply quasar
absorption line techniques to a galaxy (v_c=180 km/s) embedded in LCDM
simulations. In the simulations, MgII absorption selects metal enriched "halo"
gas out to roughly 100 kpc from the galaxy, tidal streams, filaments, and small
satellite galaxies. Within the limitations inherent in the simulations, the
majority of the simulated MgII absorption arises in the filaments and tidal
streams and is infalling towards the galaxy with velocities between -200 < v_r
< -180 km/s. The MgII absorption velocity offset distribution (relative to the
simulated galaxy) spans ~200 km/s with the lowest frequency of detecting MgII
at the galaxy systematic velocity.
