Abstract
We present the first statistical sample of rest-frame far-UV spectra of
star-forming galaxies at z~1. These spectra are unique in that they cover the
high-ionization CIVłambdałambda1548, 1550 doublet. We also detect
low-ionization features such as SiIIłambda1527, FeIIłambda1608,
AlIIłambda1670, NiIIłambdałambda1741, 1751 and SiIIłambda1808, and
intermediate-ionization features from AlIIIłambdałambda1854, 1862.
Comparing the properties of absorption lines of lower- and higher- ionization
states provides a window into the multi-phase nature of circumgalactic gas. Our
sample is drawn from the DEEP2 survey and spans the redshift range 1.01 < z <
1.35 (<z> = 1.25). By isolating the interstellar CIV absorption from the
stellar P-Cygni wind profile we find that 69% of the CIV profiles are
blueshifted with respect to the systemic velocity. Furthermore, CIV shows a
small but significant blueshift relative to FeII (offset of the best-fit linear
regression -76 $\pm$ 26 km/s). At the same time, the CIV blueshift is on
average comparable to that of MgIIłambdałambda2796, 2803. At this point,
in explaining the larger blueshift of CIV absorption at the ~ 3-sigma level, we
cannot distinguish between the faster motion of highly-ionized gas relative to
gas traced by FeII, and filling in on the red side from resonant CIV emission.
We investigate how far-UV interstellar absorption kinematics correlate with
other galaxy properties using stacked spectra. These stacking results show a
direct link between CIV absorption and the current SFR, though we only observe
small velocity differences among different ionization states tracing the
outflowing ISM.
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