Journal Article

Broad absorption line variability in radio-loud quasars

C. A. Welling, B. P. Miller, W. N. Brandt, D. M. Capellupo and R. R. Gibson

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 440, issue 3, pages 2474-2497
ISSN: 0035-8711
Published online April 2014 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1093/mnras/stu402
Broad absorption line variability in radio-loud quasars

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We investigate C iv broad absorption line (BAL) variability within a sample of 46 radio-loud quasars (RLQs), selected from Sloan Digital Sky Survey (SDSS)/Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) data to include both core-dominated (39) and lobe-dominated (7) objects. The sample consists primarily of high-ionization BAL quasars, and a substantial fraction have large BAL velocities or equivalent widths; their radio luminosities and radio-loudness values span ∼2.5 orders of magnitude. We have obtained 34 new Hobby-Eberly Telescope spectra of 28 BAL RLQs to compare to earlier SDSS data, and we also incorporate archival coverage (primarily dual-epoch SDSS) for a total set of 78 pairs of equivalent width measurements for 46 BAL RLQs, probing rest-frame time-scales of ∼80–6000 d (median 500 d). In general, only modest changes in the depths of segments of absorption troughs are observed, akin to those seen in prior studies of BAL radio-quiet quasars (RQQs). Also similar to previous findings for RQQs, the RLQs studied here are more likely to display BAL variability on longer rest-frame time-scales. However, typical values of [math] and [math] are ∼40 ± 20 per cent lower for BAL RLQs when compared with those of a time-scale-matched sample of BAL RQQs. Optical continuum variability is of similar amplitude in BAL RLQs and BAL RQQs; for both RLQs and RQQs, continuum variability tends to be stronger on longer time-scales. BAL variability in RLQs does not obviously depend upon their radio luminosities or radio-loudness values, but we do find tentative evidence for greater fractional BAL variability within lobe-dominated RLQs. Enhanced BAL variability within more edge-on (lobe-dominated) RLQs supports some geometrical dependence to the outflow structure.

Keywords: galaxies: active; galaxies: jets; quasars: absorption lines

Journal Article.  11233 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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