SOAR Imaging of sub-Damped Lyman-Alpha Systems at z<1
  We present deep ground based imaging of the environments of five QSOs that
contain sub-Damped Lyman-alpha systems at z<1 with the SOAR telescope and SOI
camera. We detect a clear surplus of galaxies in these small fields, supporting
the assumption that we are detecting the galaxies responsible for the
absorption systems. Assuming these galaxies are at the redshift of the
absorption line systems, we detect luminous L>L* galaxies for four of the five
fields within 10" of the QSO. In contrast to previous imaging surveys of DLA
systems at these redshifts, which indicate a range of morphological types and
luminosities for the host galaxies of the systems, the galaxies we detect in
these sub-DLA fields appear to be luminous (L>L*). In the case of the absorber
towards Q1009-0026 at z=0.8866 we have spectroscopic confirmation that the
candidate galaxy is at the redshift of the absorber, at an impact parameter of
~35 kpc with a luminosity of 3 < L/L* < 8 depending on the magnitude of the
K-correction. These observations are in concordance with the view that sub-DLAs
may be more representative of massive galaxies than DLA systems. The
environments of the absorbers span a range of types, from the inner disk of a
galaxy, the periphery of a luminous galaxy, and the outskirts of interacting
galaxies. The large impact parameters to some of the candidate galaxies suggest
that galactic outflows or tidal tails are likely responsible for the material
seen in absorption. We find a weak correlation between N(HI) and the impact
parameter at the 2 sigma level, which may be expected from the heterogeneous
population of galaxies hosting the absorption line systems and random
orientation angles. In addition, we detect a possible gravitationally lensed
image of the BL-Lac object Q0826-2230.
