The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* Galaxies
  We report new observations of circumgalactic gas from the COS-Dwarfs survey,
a systematic investigation of the gaseous halos around 43 low-mass z $\leq$ 0.1
galaxies using background QSOs observed with the Cosmic Origins Spectrograph.
From the projected 1D and 2D distribution of C IV absorption, we find that C IV
absorption is detected out to ~ 0.5 R$_{vir}$ of the host galaxies. The C IV
absorption strength falls off radially as a power law and beyond 0.5 R$_{vir}$,
no C IV absorption is detected above our sensitivity limit of ~ 50-100 m$\AA$.
We find a tentative correlation between detected C IV absorption strength and
star formation, paralleling the strong correlation seen in highly ionized
oxygen for L~L* galaxies by the COS-Halos survey. The data imply a large carbon
reservoir in the CGM of these galaxies, corresponding to a minimum carbon mass
of $\gtrsim$ 1.2$\times 10^6$ $M_\odot$ out to ~ 110 kpc. This mass is
comparable to the carbon mass in the ISM and more than the carbon mass
currently in stars of these galaxies. The C IV absorption seen around these
sub-L* galaxies can account for almost two-thirds of all $W_r$> 100 m$\AA$ C IV
absorption detected at low z. Comparing the C IV covering fraction with
hydrodynamical simulations, we find that an energy-driven wind model is
consistent with the observations whereas a wind model of constant velocity
fails to reproduce the CGM or the galaxy properties.
