X-Ray Insights into the Nature of Quasars with Redshifted Broad Absorption Lines

Abstract

We present Chandra observations of seven broad absorption line (BAL) quasars at with redshifted BAL troughs (RSBALs). Five of our seven targets were detected by Chandra in 4–13 ks exposures with ACIS-S. The values, values, and spectral energy distributions of our targets demonstrate they are all X-ray weak relative to expectations for non-BAL quasars, and the degree of X-ray weakness is consistent with that of appropriately matched BAL quasars generally. Furthermore, our five detected targets show evidence for hard X-ray spectral shapes with a stacked effective power-law photon index of . These findings support the presence of heavy X-ray absorption ( cm −2 ) in RSBAL quasars, likely by the shielding gas found to be common in BAL quasars more generally. We use these X-ray measurements to assess models for the nature of RSBAL quasars, finding that a rotationally dominated outflow model is favored while an infall model also remains plausible with some stipulations. The X-ray data disfavor a binary quasar model for RSBAL quasars in general.