The Geometry of Cold, Metal-Enriched Gas Around Galaxies at $z\sim1.2$
  We present the first results from a Hubble Space Telescope WFC3/IR program,
which obtained direct imaging and grism observations of galaxies near quasar
sightlines with a high frequency of uncorrelated foreground Mg II absorption.
These highly efficient observations targeted 54 Mg II absorbers along the line
of sight to nine quasars at $z_{qso}\sim2$. We find that 89% of the absorbers
in the range $0.64< z < 1.6$ can be spectroscopically matched to at least one
galaxy with an impact parameter less than 200 kpc and $|\Delta z|/(1+z)<0.006$.
We have estimated the star formation rates and measured structural parameters
for all detected galaxies with impact parameters in the range 7-200 kpc and
star formation rates greater than 1.3 M$_{\odot}$ yr$^{-1}$. We find that
galaxies associated with Mg II absorption have significantly higher mean star
formation rates and marginally higher mean star formation rate surface
densities compared to galaxies with no detected Mg II. Nearly half of the Mg II
absorbers match to more than one galaxy, and the mean equivalent width of the
Mg II absorption is found to be greater for groups, compared to isolated
galaxies. Additionally, we observe a significant redshift evolution in the
physical extent of Mg II-absorbing gas around galaxies and evidence of an
enhancement of Mg II within 50 degrees of the minor axis, characteristic of
outflows, which persists to 80 kpc around the galaxies, in agreement with
recent predictions from simulations.
