The C IV Absorption-Mg II Kinematics Connection in <Z> ~ 0.7 Galaxies

Abstract

We have examined Faint Object Spectrograph data from the Hubble Space Telescope archive for C IV λλ1548, 1550 absorption associated with 40 Mg II λλ2796, 2803 absorption-selected galaxies at 0.4<=z<=1.4. We report a strong correlation between Mg II kinematics, measured in ~6 km s^-1 resolution HIRES/Keck spectra, and W_r(1548); this implies a physical connection between the processes that produce ``outlying velocity'' Mg II clouds and high-ionization galactic/halo gas. We found no trend in ionization condition W_r(1548)/W_r(2796) with galaxy-QSO line-of-sight separation for 13 systems with confirmed associated galaxies, suggesting no obvious ionization gradient with galactocentric distance in these intermediate-redshift galaxies. We find tentative evidence (2 σ) that W_r(1548)/W_r(2796) is anticorrelated with galaxy B-K color; if further data corroborate this trend, in view of the strong C IV-Mg II kinematics correlation, it could imply a connection between stellar populations, star formation episodes, and the kinematics and ionization conditions of halo gas at z~1.