COS-Burst: Observations of the Impact of Starburst-Driven Winds on the
  Properties of the Circum-Galactic Medium
  We report on observations made with the Cosmic Origins Spectrograph (COS) on
the Hubble Space Telescope (HST) using background QSOs to probe the
circum-galactic medium (CGM) around 17 low-redshift galaxies that are
undergoing or have recently undergone a strong starburst (the COS-Burst
program). The sightlines extend out to roughly the virial radius of the galaxy
halo. We construct control samples of normal star-forming low-redshift galaxies
from the COS/HST archive that match the starbursts in terms of galaxy stellar
mass and impact parameter.
  We find clear evidence that the CGM around the starbursts differs
systematically compared to the control galaxies. The Ly$\alpha$, Si III, C IV,
and possibly O VI absorption-lines are stronger as a function of impact
parameter, and the ratios of the equivalent widths of C IV/Ly$\alpha$ and Si
III/Ly$\alpha$ are both larger than in normal star-forming galaxies. We also
find that the widths and the velocity offsets (relative to $v_{sys}$) of the
Ly$\alpha$ absorption-lines are significantly larger in the CGM of the
starbursts, implying velocities of the absorbing material that are roughly
twice the halo virial velocity.
  We show that these properties can be understood as a consequence of the
interaction between a starburst-driven wind and the pre-existing CGM. These
results underscore the importance of winds driven from intensely star-forming
galaxies in helping drive the evolution of galaxies and the intergalactic
medium. They also offer a new probe of the properties of starburst-driven winds
and of the CGM itself.
