The Structure of the Circumgalactic Medium of Galaxies: Cool Accretion
  Inflow Around NGC 1097
  We present Hubble Space Telescope far-UV spectra of 4 QSOs whose sightlines
pass through the halo of NGC 1097 at impact parameters of 48 -165 kpc. NGC 1097
is a nearby spiral galaxy that has undergone at least two minor merger events,
but no apparent major mergers, and is relatively isolated with respect to other
nearby bright galaxies. This makes NGC 1097 a good case study for exploring
baryons in a paradigmatic bright-galaxy halo. Lyman-alpha absorption is
detected along all sightlines and Si III 1206 is found along the 3 smallest
impact parameter sightlines; metal lines of C II, Si II and Si IV are only
found with certainty towards the inner-most sightline. The kinematics of the
absorption lines are best replicated by a model with a disk-like distribution
of gas approximately planar to the observed 21 cm H I disk, that is rotating
more slowly than the inner disk, and into which gas is infalling from the
intergalactic medium. Some part of the absorption towards the inner-most
sightline may arise either from a small-scale outflow, or from tidal debris
associated with the minor merger that gives rise to the well known `dog-leg'
stellar stream that projects from NGC 1097. When compared to other studies, NGC
1097 appears to be a `typical' absorber, although the large dispersion in
absorption line column density and equivalent width in a single halo goes
perhaps some way in explaining the wide range of these values seen in
higher-redshift studies.
