The Correlated Variations of Narrow Absorption Lines and Quasar Continuum

Abstract

Abstract We assemble 207 variable quasars from the Sloan Digital Sky Survey, all with at least 3 observations, to analyze C iv narrow absorption doublets, and obtain 328 C iv narrow absorption line systems. We find that 19 out of 328 C iv narrow absorption line systems were changed by on timescales from 15.9 to 1477 days at rest-frame. Among the 19 obviously variable C iv systems, we find that (1) 14 systems have relative velocities and 4 systems have , where c is the speed of light; (2) 13 systems are accompanied by other variable C iv systems; (3) 9 systems were changed continuously during multiple observations; and (4) 1 system with 16,862 km s −1 was enhanced by in 0.67 day at rest-frame. The variations of absorption lines are inversely correlated with the changes in the ionizing continuum. We also find that large variations of C iv narrow absorption lines are form differently over a short timescale.