BAL Quasars with Redshifted Troughs

We report the discovery in the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey of ten to twelve broad absorption line (BAL) quasars with high-ionization troughs which include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to similar to 9000 km s(-1) and the trough widths exceed 3000 km s(-1) in all but one case. Approximately 1 in 1200 BAL quasars with blueshifted C IV absorption also has redshifted C IV absorption. There are several potentially viable ways to generate redshifted absorption which may be at work simultaneously (in the same objects or in different ones). Cases of infall or rotationally dominated outflows silhouetted against a quasar's extended continuum source would challenge current theoretical models of BAL quasars. Cases of outflows from one member of an unresolved binary quasar pair seen in absorption against the other, possibly with a contribution from the relativistic Doppler effect in gas moving at high velocity close to transverse to our line of sight, would provide new sightlines which literally cross-examine BAL outflows.