Properties of Radio-Selected Broad Absorption-Line Quasars from the FIRST Survey

摘要

In a spectroscopic follow-up to the VLA FIRST survey, the FIRST Bright QuasarSurvey (FBQS) has found 29 radio-selected broad absorption line (BAL) quasars.This sample provides the first opportunity to study the properties ofradio-selected BAL quasars. Contrary to most previous studies, we establishthat a significant population of radio-loud BAL quasars exists. Radio-selectedBAL quasars display compact radio morphologies and possess both steep and flatradio spectra. Quasars with low-ionization BALs have a color distributionredder than that of the FBQS sample as a whole. The frequency of BAL quasars inthe FBQS is significantly greater, perhaps by as much as a factor of two, thanthat inferred from optically selected samples. The frequency of BAL quasarsappears to have a complex dependence on radio-loudness. The properties of thissample appear inconsistent with simple unified models in which BAL quasarsconstitute a subset of quasars seen edge-on.