The Column Density, Kinematics, and Thermal State of Metal-Bearing Gas
  within the Virial Radius of z~2 Star-Forming Galaxies in the Keck Baryonic
  Structure Survey
  We present results from the Keck Baryonic Structure Survey (KBSS) including
the first detailed measurements of the column densities, kinematics, and
internal energy of metal-bearing gas within the virial radius (35-100 physical
kpc) of eight ~$L^*$ galaxies at $z\sim2$. From our full sample of 130
metal-bearing absorbers, we infer that halo gas is kinematically complex when
viewed in singly, doubly, and triply ionized species. Broad OVI and CIV
absorbers are detected at similar velocities to the lower-ionization gas but
with very different kinematic structure indicating that the circumgalactic
medium (CGM) is multi-phase. There is a high covering fraction of metal-bearing
gas within 100 kpc including highly ionized gas such as OVI; however,
observations of a single galaxy probed by a lensed background QSO suggest the
size of metal-bearing clouds is small (<400 pc for all but the OVI-bearing
gas). The mass in metals found within the halo is substantial, equivalent to
$\gtrsim$ 25% of the metal mass within the interstellar medium. The gas
kinematics unambiguously show that 70% of galaxies with detected metal
absorption have some unbound metal-enriched gas, suggesting galactic winds may
commonly eject gas from halos at $z\sim2$. Significant thermal broadening is
detected in CGM absorbers which dominates the internal energy of the gas. 40%
of the detected gas has temperatures in the range $10^{4.5-5.5}$ K where
cooling times are short, suggesting the CGM is dynamic, with constant heating
and/or cooling to produce this short-lived thermal phase.
