A Chandra Survey of the X-ray Properties of Broad Absorption Line Radio-Loud Quasars

TL;DR

This study uses Chandra X-ray observations to analyze the properties of broad absorption line radio-loud quasars, revealing they are less X-ray luminous than non-BAL RLQs but not as X-ray weak as BAL RQQs, with varied spectral hardness.

Contribution

First comprehensive X-ray survey of BAL radio-loud quasars comparing their properties to non-BAL RLQs and BAL RQQs, highlighting differences in X-ray luminosity and spectral characteristics.

Findings

BAL RLQs are X-ray weaker than non-BAL RLQs by factors of 4.1-8.5.

Some BAL RLQs exhibit harder X-ray spectra, others are similar to non-BAL RLQs.

BAL RLQs are less X-ray weak than BAL RQQs, indicating different obscuration or geometry.

Abstract

This work presents the results of a Chandra study of 21 broad absorption line (BAL) radio-loud quasars (RLQs). We conducted a Chandra snapshot survey of 12 bright BAL RLQs selected from SDSS/FIRST data and possessing a wide range of radio and CIV absorption properties. Optical spectra were obtained nearly contemporaneously with the Hobby-Eberly Telescope; no strong flux or BAL variability was seen between epochs. We also include in our sample 9 additional BAL RLQs possessing archival Chandra coverage. We compare the properties of (predominantly high-ionization) BAL RLQs to those of non-BAL RLQs as well as to BAL radio-quiet quasars (RQQs) and non-BAL RQQs for context. All 12 snapshot and 8/9 archival BAL RLQs are detected, with observed X-ray luminosities less than those of non-BAL RLQs having comparable optical/UV luminosities by typical factors of 4.1-8.5. (BAL RLQs are also X-ray weak by typical factors of 2.0-4.5 relative to non-BAL RLQs having both comparable optical/UV and radio luminosities.) However, BAL RLQs are not as X-ray weak relative to non-BAL RLQs as are BAL RQQs relative to non-BAL RQQs. While some BAL RLQs have harder X-ray spectra than typical non-BAL RLQs, some have hardness ratios consistent with those of non-BAL RLQs, and there does not appear to be a correlation between X-ray weakness and spectral hardness, in contrast to the situation for BAL RQQs. RLQs are expected to have X-ray continuum contributions from both disk-corona and small-scale jet emission. While the entire X-ray continuum in BAL RLQs cannot be obscured to the same degree as in BAL RQQs, we calculate that the jet is likely partially covered in many BAL RLQs. We comment briefly on implications for geometries and source ages in BAL RLQs.