2016/04/30 by Xinnan Du, Xinnan 杜辛楠 Du, Alice E. Shapley +2
Physics and Astronomy · #Absorption (acoustics) #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Blueshift #Galaxies: Formation, Evolution, Phenomena #Galaxy #Interstellar medium #Ionization #Redshift #Spectral line #astro-ph.GA
paper · pdf · doi:10.3847/0004-637x/829/2/64
21 pages, 14 figures, ApJ, accepted
openalex created_date 2016/06/24 · arxiv created 2016/07/18 · openalex publication_date 2016/09/22 · arxiv updated 2016/10/05 · openalex updated_date 2026/08/05
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 C iv λλ 1548, 1550 doublet. We also detect low-ionization features such as Si ii λ 1526, Fe ii λ 1608, Al ii λ 1670, Ni ii λλ 1741, 1751, and Si ii λ 1808, and intermediate-ionization features from Al iii λλ 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 ( ). 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 λλ 2796, 2803. At this point, in explaining the larger blueshift of C iv absorption at the ∼3 σ 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.