Broad Absorption Line Quasars in the Sloan Digital Sky Survey with VLA-FIRST Radio Detections

Abstract

We present 13 Broad Absorption Line (BAL) quasars, including 12 new objects, which were identified in the Sloan Digital Sky Survey (SDSS) and matched within 2'' to sources in the FIRST radio survey catalog. The surface density of this sample of radio-detected BAL quasars is 4.5 +- 1.2 per 100 deg^2, i.e. approximately 4 times larger than previously found by the shallower FIRST Bright Quasar Survey (FBQS). A majority of these radio-detected BAL quasars are moderately radio-loud objects. The fraction of BAL quasars in the entire radio quasar sample, 4.8 +- 1.3 %, is comparable to the fraction of BAL quasars among the SDSS optical quasar sample (ignoring selection effects). We estimate that the true fraction of BAL quasars (mostly HiBALs) in the radio sample is 9.2 +- 2.6 % once selection effects are accounted for. We caution that the absorption troughs of 4 of the 13 radio-detected quasars considered do not strictly satisfy the standard BALnicity criterion. One or possibly two of the new radio-detected BAL quasars are of the rare ``iron LoBAL'' type. BAL quasars are generally redder than the median SDSS quasar at the same redshift.