THE KINEMATICS OF C IV IN STAR-FORMING GALAXIES AT z ∼ 1.2

We present the first statistical sample of rest-frame far-UV spectra of star-forming galaxies at z similar to 1. These spectra are unique in that they cover the high-ionization C IV lambda lambda 1548, 1550 doublet. We also detect low-ionization features such as Si II lambda 1526, Fe II lambda 1608, Al II lambda 1670, Ni II lambda lambda 1741, 1751, and Si II lambda 1808, and intermediate-ionization features from Al III lambda lambda 1854, 1862. Comparing the properties of absorption lines of lower- and higher-ionization states provides a window into the multiphase 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 C IV absorption from the stellar P. Cygni wind profile, we find that 69% of the C IV profiles are blueshifted with respect to the systemic velocity. Furthermore, C IV shows a small but significant blueshift relative to Fe II (offset of the best-fit linear regression -76 +/- 26 km s(-1)). At the same time, the C IV blueshift is on average comparable to that of Mg II lambda lambda 2796, 2803. At this point, in explaining the larger blueshift of C IV absorption at the similar to 3 sigma. level, we cannot distinguish between the faster motion of highly ionized gas relative to gas traced by Fe II. and filling in on the red side from resonant C IV 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 C IV absorption and the current star formation rate, though we only observe small velocity differences among different ionization states tracing the outflowing interstellar medium.