Broad absorption line quasars with redshifted troughs: High-velocity infall or rotationally dominated outflows?

P. B. Hall, W. N. Brandt, P. Petitjean, I. Pâris, N. Filiz Ak, Yue Shen, R. R. Gibson, É Aubourg, S. F. Anderson, D. P. Schneider, D. Bizyaev, J. Brinkmann, E. Malanushenko, V. Malanushenko, A. D. Myers, D. J. Oravetz, N. P. Ross, A. Shelden, A. E. Simmons, A. StreblyanskaB. A. Weaver, D. G. York

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

We report the discovery in the Sloan Digital Sky Survey (SDSS) and the SDSS-III Baryon Oscillation Spectroscopic Survey of 17 broad absorption line (BAL) quasars with high-ionization troughs that include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to v ≃ 12 000 km s-1 and the trough widths exceed 3000 km s-1 in all but one case. Approximately 1 in 1000 BAL quasars with blueshifted CIV absorption also has redshifted C IV absorption; objects with CIV absorption present only at redshifted velocities are roughly four times rarer. In more than half of our objects, redshifted absorption is seen in CII or Al III as well as CIV, making low-ionization absorption at least 10 times more common among BAL quasars with redshifted troughs than among standard BAL quasars. However, the CIV absorption equivalent widths in our objects are on average smaller than those of standard BAL quasars with low-ionization absorption. We consider several possible ways of generating redshifted absorption. The two most likely possibilities may be at work simultaneously, in the same objects or in different ones. Rotationally dominated outflows seen against a quasar's extended continuum source can produce redshifted and blueshifted absorption, but variability consistent with this scenario is seen in only one of the four objects with multiple spectra. The infall of relatively dense and lowionization gas to radii as small as 400 Schwarzschild radii can in principle explain the observed range of trough profiles, but current models do not easily explain the origin and survival of such gas. Whatever the origin(s) of the absorbing gas in these objects, it must be located at small radii to explain its large redshifted velocities, and thus offers a novel probe of the inner regions of quasars.

Original languageEnglish (US)
Pages (from-to)222-256
Number of pages35
JournalMonthly Notices of the Royal Astronomical Society
Volume434
Issue number1
DOIs
StatePublished - Sep 1 2013

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troughs
quasars
trough
outflow
ionization
radii
gases
gas
baryons
oscillation

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Hall, P. B. ; Brandt, W. N. ; Petitjean, P. ; Pâris, I. ; Ak, N. Filiz ; Shen, Yue ; Gibson, R. R. ; Aubourg, É ; Anderson, S. F. ; Schneider, D. P. ; Bizyaev, D. ; Brinkmann, J. ; Malanushenko, E. ; Malanushenko, V. ; Myers, A. D. ; Oravetz, D. J. ; Ross, N. P. ; Shelden, A. ; Simmons, A. E. ; Streblyanska, A. ; Weaver, B. A. ; York, D. G. / Broad absorption line quasars with redshifted troughs : High-velocity infall or rotationally dominated outflows?. In: Monthly Notices of the Royal Astronomical Society. 2013 ; Vol. 434, No. 1. pp. 222-256.
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title = "Broad absorption line quasars with redshifted troughs: High-velocity infall or rotationally dominated outflows?",
abstract = "We report the discovery in the Sloan Digital Sky Survey (SDSS) and the SDSS-III Baryon Oscillation Spectroscopic Survey of 17 broad absorption line (BAL) quasars with high-ionization troughs that include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to v ≃ 12 000 km s-1 and the trough widths exceed 3000 km s-1 in all but one case. Approximately 1 in 1000 BAL quasars with blueshifted CIV absorption also has redshifted C IV absorption; objects with CIV absorption present only at redshifted velocities are roughly four times rarer. In more than half of our objects, redshifted absorption is seen in CII or Al III as well as CIV, making low-ionization absorption at least 10 times more common among BAL quasars with redshifted troughs than among standard BAL quasars. However, the CIV absorption equivalent widths in our objects are on average smaller than those of standard BAL quasars with low-ionization absorption. We consider several possible ways of generating redshifted absorption. The two most likely possibilities may be at work simultaneously, in the same objects or in different ones. Rotationally dominated outflows seen against a quasar's extended continuum source can produce redshifted and blueshifted absorption, but variability consistent with this scenario is seen in only one of the four objects with multiple spectra. The infall of relatively dense and lowionization gas to radii as small as 400 Schwarzschild radii can in principle explain the observed range of trough profiles, but current models do not easily explain the origin and survival of such gas. Whatever the origin(s) of the absorbing gas in these objects, it must be located at small radii to explain its large redshifted velocities, and thus offers a novel probe of the inner regions of quasars.",
author = "Hall, {P. B.} and Brandt, {W. N.} and P. Petitjean and I. P{\^a}ris and Ak, {N. Filiz} and Yue Shen and Gibson, {R. R.} and {\'E} Aubourg and Anderson, {S. F.} and Schneider, {D. P.} and D. Bizyaev and J. Brinkmann and E. Malanushenko and V. Malanushenko and Myers, {A. D.} and Oravetz, {D. J.} and Ross, {N. P.} and A. Shelden and Simmons, {A. E.} and A. Streblyanska and Weaver, {B. A.} and York, {D. G.}",
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Hall, PB, Brandt, WN, Petitjean, P, Pâris, I, Ak, NF, Shen, Y, Gibson, RR, Aubourg, É, Anderson, SF, Schneider, DP, Bizyaev, D, Brinkmann, J, Malanushenko, E, Malanushenko, V, Myers, AD, Oravetz, DJ, Ross, NP, Shelden, A, Simmons, AE, Streblyanska, A, Weaver, BA & York, DG 2013, 'Broad absorption line quasars with redshifted troughs: High-velocity infall or rotationally dominated outflows?', Monthly Notices of the Royal Astronomical Society, vol. 434, no. 1, pp. 222-256. https://doi.org/10.1093/mnras/stt1012

Broad absorption line quasars with redshifted troughs : High-velocity infall or rotationally dominated outflows? / Hall, P. B.; Brandt, W. N.; Petitjean, P.; Pâris, I.; Ak, N. Filiz; Shen, Yue; Gibson, R. R.; Aubourg, É; Anderson, S. F.; Schneider, D. P.; Bizyaev, D.; Brinkmann, J.; Malanushenko, E.; Malanushenko, V.; Myers, A. D.; Oravetz, D. J.; Ross, N. P.; Shelden, A.; Simmons, A. E.; Streblyanska, A.; Weaver, B. A.; York, D. G.

In: Monthly Notices of the Royal Astronomical Society, Vol. 434, No. 1, 01.09.2013, p. 222-256.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Broad absorption line quasars with redshifted troughs

T2 - High-velocity infall or rotationally dominated outflows?

AU - Hall, P. B.

AU - Brandt, W. N.

AU - Petitjean, P.

AU - Pâris, I.

AU - Ak, N. Filiz

AU - Shen, Yue

AU - Gibson, R. R.

AU - Aubourg, É

AU - Anderson, S. F.

AU - Schneider, D. P.

AU - Bizyaev, D.

AU - Brinkmann, J.

AU - Malanushenko, E.

AU - Malanushenko, V.

AU - Myers, A. D.

AU - Oravetz, D. J.

AU - Ross, N. P.

AU - Shelden, A.

AU - Simmons, A. E.

AU - Streblyanska, A.

AU - Weaver, B. A.

AU - York, D. G.

PY - 2013/9/1

Y1 - 2013/9/1

N2 - We report the discovery in the Sloan Digital Sky Survey (SDSS) and the SDSS-III Baryon Oscillation Spectroscopic Survey of 17 broad absorption line (BAL) quasars with high-ionization troughs that include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to v ≃ 12 000 km s-1 and the trough widths exceed 3000 km s-1 in all but one case. Approximately 1 in 1000 BAL quasars with blueshifted CIV absorption also has redshifted C IV absorption; objects with CIV absorption present only at redshifted velocities are roughly four times rarer. In more than half of our objects, redshifted absorption is seen in CII or Al III as well as CIV, making low-ionization absorption at least 10 times more common among BAL quasars with redshifted troughs than among standard BAL quasars. However, the CIV absorption equivalent widths in our objects are on average smaller than those of standard BAL quasars with low-ionization absorption. We consider several possible ways of generating redshifted absorption. The two most likely possibilities may be at work simultaneously, in the same objects or in different ones. Rotationally dominated outflows seen against a quasar's extended continuum source can produce redshifted and blueshifted absorption, but variability consistent with this scenario is seen in only one of the four objects with multiple spectra. The infall of relatively dense and lowionization gas to radii as small as 400 Schwarzschild radii can in principle explain the observed range of trough profiles, but current models do not easily explain the origin and survival of such gas. Whatever the origin(s) of the absorbing gas in these objects, it must be located at small radii to explain its large redshifted velocities, and thus offers a novel probe of the inner regions of quasars.

AB - We report the discovery in the Sloan Digital Sky Survey (SDSS) and the SDSS-III Baryon Oscillation Spectroscopic Survey of 17 broad absorption line (BAL) quasars with high-ionization troughs that include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to v ≃ 12 000 km s-1 and the trough widths exceed 3000 km s-1 in all but one case. Approximately 1 in 1000 BAL quasars with blueshifted CIV absorption also has redshifted C IV absorption; objects with CIV absorption present only at redshifted velocities are roughly four times rarer. In more than half of our objects, redshifted absorption is seen in CII or Al III as well as CIV, making low-ionization absorption at least 10 times more common among BAL quasars with redshifted troughs than among standard BAL quasars. However, the CIV absorption equivalent widths in our objects are on average smaller than those of standard BAL quasars with low-ionization absorption. We consider several possible ways of generating redshifted absorption. The two most likely possibilities may be at work simultaneously, in the same objects or in different ones. Rotationally dominated outflows seen against a quasar's extended continuum source can produce redshifted and blueshifted absorption, but variability consistent with this scenario is seen in only one of the four objects with multiple spectra. The infall of relatively dense and lowionization gas to radii as small as 400 Schwarzschild radii can in principle explain the observed range of trough profiles, but current models do not easily explain the origin and survival of such gas. Whatever the origin(s) of the absorbing gas in these objects, it must be located at small radii to explain its large redshifted velocities, and thus offers a novel probe of the inner regions of quasars.

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