Morphological Properties of z~0.5 Absorption-Selected Galaxies: The Role
  of Galaxy Inclination
  We have used GIM2D to quantify the morphological properties of 40
intermediate redshift MgII absorption-selected galaxies (0.03<Wr(2796)<2.9
Ang), imaged with WFPC-2/HST, and compared them to the halo gas properties
measured form HIRES/Keck and UVES/VLT quasar spectra. We find that as the
quasar-galaxy separation, D, increases the MgII equivalent decreases with large
scatter, implying that D is not the only physical parameter affecting the
distribution and quantity of halo gas. Our main result shows that inclination
correlates with MgII absorption properties after normalizing out the
relationship (and scatter) between the absorption properties and D. We find a
4.3 sigma correlation between Wr(2796) and galaxy inclination, normalized by
impact parameter, i/D. Other measures of absorption optical depth also
correlate with i/D at greater than 3.2 sigma significance. Overall, this result
suggests that MgII gas has a co-planer geometry, not necessarily disk-like,
that is coupled to the galaxy inclination. It is plausible that the absorbing
gas arises from tidal streams, satellites, filaments, etc., which tend to have
somewhat co-planer distributions. This result does not support a picture in
which MgII absorbers with Wr(2796)<1A are predominantly produced by
star-formation driven winds. We further find that; (1) MgII host galaxies have
quantitatively similar bulge and disk scale length distribution to field
galaxies at similar redshifts and have a mean disk and bulge scale length of
3.8kpc and 2.5kpc, respectively; (2) Galaxy color and luminosity do not
correlate strongly with absorption properties, implying a lack of a connection
between host galaxy star formation rates and absorption strength; (3)
Parameters such as scale lengths and bulge-to-total ratios do not significantly
correlate with the absorption parameters, suggesting that the absorption is
independent of galaxy size or mass.
