Broad absorption line variability in radio-loud quasars

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

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

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 . |ΔEW| and |ΔEW|/〈EW〉 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.

Original languageEnglish (US)
Pages (from-to)2474-2497
Number of pages24
JournalMonthly Notices of the Royal Astronomical Society
Volume440
Issue number3
DOIs
StatePublished - May 2014

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quasars
radio
lobes
loudness
timescale
luminosity
continuums
troughs
sky

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Welling, C. A. ; Miller, B. P. ; Brandt, W. N. ; Capellupo, D. M. ; Gibson, R. R. / Broad absorption line variability in radio-loud quasars. In: Monthly Notices of the Royal Astronomical Society. 2014 ; Vol. 440, No. 3. pp. 2474-2497.
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Broad absorption line variability in radio-loud quasars. / Welling, C. A.; Miller, B. P.; Brandt, W. N.; Capellupo, D. M.; Gibson, R. R.

In: Monthly Notices of the Royal Astronomical Society, Vol. 440, No. 3, 05.2014, p. 2474-2497.

Research output: Contribution to journalArticle

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T1 - Broad absorption line variability in radio-loud quasars

AU - Welling, C. A.

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AU - Brandt, W. N.

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AU - Gibson, R. R.

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N2 - 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 . |ΔEW| and |ΔEW|/〈EW〉 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.

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