Galaxy Group at z=0.3 Associated with the Damped Lyman Alpha System
  Towards Quasar Q1127-145
  (Abridged) We performed a spectroscopic galaxy survey, complete to m<20.3
(L_B>0.15L_B* at z=0.3), within 100x100" of the quasar Q1127-145 (z=1.18). The
VLT/UVES quasar spectrum contains three z<0.33 MgII absorption systems. We
obtained eight new galaxy redshifts, adding to the four previously known, and
galaxy star formation rates and metallicities were computed where possible. A
strong MgII system [W_r(2796)=1.8A], which is a known DLA, had three previously
identified galaxies; we found two additional galaxies associated with this
system. These five galaxies form a group with diverse properties, such as a
luminosity range of 0.04<L_B<0.63L_B*, an impact parameter range of 17<D<241kpc
and velocity dispersion of 115km/s. The DLA group galaxy redshifts span beyond
the 350km/s velocity spread of the metallic absorption lines of the DLA itself.
The two brightest group galaxies have SFRs of a few Msun/yr and should not have
strong winds. We have sufficient spectroscopic information to directly compare
three of the five group galaxies' (emission-line) metallicities with the DLA
(absorption) metallicity: the DLA metallicity is 1/10th solar, substantially
lower than the three galaxies' which range between less than 1/2 solar to solar
metallicity. HST/WFPC-2 imaging shows perturbed morphologies for the three
brightest group galaxies, with tidal tails extending 25kpc. We favor a scenario
where the DLA absorption originates from tidal debris in the group environment.
Another absorber exhibits weak MgII absorption [W_r(2796)=0.03A] and had a
previously identified galaxy at a similar redshift. We have identified a second
galaxy associated with this system. Both galaxies have solar metallicities and
unperturbed morphologies. The SFR of one galaxy is much lower than expected for
strong outflows. Finally, we have identified five galaxies at large impact
parameters with no associated MgII absorption.
