Broad Absorption Line Quasars in the Early Data Release from the Sloan Digital Sky Survey

Abstract

A new broad absorption line quasar (BAL) sample is derived from the first data released by the Sloan Digital Sky Survey. With 116 objects, it is the largest BAL sample yet assembled. Over the redshift range 1.8 < z < 3.8, the crude fraction with broad absorption in the CIV line is roughly 15%. This fraction may be subject to small selection-efficiency adjustments. There are also hints of redshift-dependence in the BAL fraction. The sample is large enough to permit the first estimate of the distribution of &#34;balnicity index&#34;: subject to certain arbitrary parameters in the definition of this quantity, it is very broad, with (roughly) equal numbers of objects per logarithmic interval of balnicity. BAL quasars are also found to be redder on average than non-BAL quasars. The fraction of radio-loud BAL quasars is (weakly) consistent with the fraction of radio-loud ordinary quasars.