The Properties of the Circumgalactic Medium in Red and Blue Galaxies:
  Results from the COS-GASS+COS-Halos Surveys
  We use the combined data from the COS-GASS and COS-Halos surveys to
characterize the Circum-Galactic Medium (CGM) surrounding typical low-redshift
galaxies in the mass range $\rm~M_*\sim~10^{9.5-11.5}~M_{\odot} $, and over a
range of impact parameters extending to just beyond the halo virial radius
($\rm~R_{vir}$). We find the radial scale length of the distributions of the
equivalent widths of the Lyman~$\alpha$ and Si III absorbers to be 0.9 and 0.4
$\rm~R_{vir}$, respectively. The radial distribution of equivalent widths is
relatively uniform for the blue galaxies, but highly patchy (low covering
fraction) for the red galaxies. We also find that the Lyman~$\alpha$ and Si III
equivalent widths show significant positive correlations with the specific
star-formation rate (sSFR) of the galaxy. We find a surprising lack of
correlations between the halo mass (virial velocity) and either the velocity
dispersions or velocity offsets of the Lyman~$\alpha$ lines. The ratio of the
velocity offset to the velocity dispersion for the Lyman~$\alpha$ absorbers has
a mean value of $\sim$ 4, suggesting that a given the line-of-sight is
intersecting a dynamically coherent structure in the CGM rather than a sea of
orbiting clouds. The kinematic properties of the CGM are similar in the blue
and red galaxies, although we find that a significantly larger fraction of the
blue galaxies have large Lyman~$\alpha$ velocity offsets (>200 km s$^{-1}$). We
show that - if the CGM clouds represent future fuel for star-formation - our
new results could imply a large drop in the specific star-formation rate across
the galaxy mass-range we probe.
