PHL 1092 as a transient extreme X-ray weak quasar

G. Miniutti, A. C. Fabian, William Nielsen Brandt, L. C. Gallo, Th Boller

Research output: Contribution to journalLetter

18 Citations (Scopus)

Abstract

We report a dramatic variability event in the X-ray history of the narrow-line quasar PHL 1092 (z = 0.396). Our latest 2008 XMM-Newton observation reveals a flux drop of ~200 with respect to the previous observation performed about 4.5 yr earlier, and a drop of ~ 135 with respect to its historical flux. Despite the huge X-ray variation, the UV flux remains constant producing a very significant steepening of the optical to X-ray slope αox from -1.56 to -2.44, making PHL 1092 one of the most extreme X-ray weak quasars. The similarity in the soft X-ray spectral shape between the present and previous observations, together with the persistent UV flux and the lack of any dramatic change in the optical spectrum, suggests that an absorption event is not likely to be the origin of the observed variation. If absorption is ruled out, the sudden X-ray weakness of PHL 1092 must be produced by a transient significant weakening or disruption of the X-ray emitting corona.

Original languageEnglish (US)
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume396
Issue number1
DOIs
StatePublished - Jun 1 2009

Fingerprint

quasars
x rays
XMM-Newton telescope
newton
coronas
corona
optical spectrum
histories
slopes
history

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Miniutti, G. ; Fabian, A. C. ; Brandt, William Nielsen ; Gallo, L. C. ; Boller, Th. / PHL 1092 as a transient extreme X-ray weak quasar. In: Monthly Notices of the Royal Astronomical Society: Letters. 2009 ; Vol. 396, No. 1.
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abstract = "We report a dramatic variability event in the X-ray history of the narrow-line quasar PHL 1092 (z = 0.396). Our latest 2008 XMM-Newton observation reveals a flux drop of ~200 with respect to the previous observation performed about 4.5 yr earlier, and a drop of ~ 135 with respect to its historical flux. Despite the huge X-ray variation, the UV flux remains constant producing a very significant steepening of the optical to X-ray slope αox from -1.56 to -2.44, making PHL 1092 one of the most extreme X-ray weak quasars. The similarity in the soft X-ray spectral shape between the present and previous observations, together with the persistent UV flux and the lack of any dramatic change in the optical spectrum, suggests that an absorption event is not likely to be the origin of the observed variation. If absorption is ruled out, the sudden X-ray weakness of PHL 1092 must be produced by a transient significant weakening or disruption of the X-ray emitting corona.",
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PHL 1092 as a transient extreme X-ray weak quasar. / Miniutti, G.; Fabian, A. C.; Brandt, William Nielsen; Gallo, L. C.; Boller, Th.

In: Monthly Notices of the Royal Astronomical Society: Letters, Vol. 396, No. 1, 01.06.2009.

Research output: Contribution to journalLetter

TY - JOUR

T1 - PHL 1092 as a transient extreme X-ray weak quasar

AU - Miniutti, G.

AU - Fabian, A. C.

AU - Brandt, William Nielsen

AU - Gallo, L. C.

AU - Boller, Th

PY - 2009/6/1

Y1 - 2009/6/1

N2 - We report a dramatic variability event in the X-ray history of the narrow-line quasar PHL 1092 (z = 0.396). Our latest 2008 XMM-Newton observation reveals a flux drop of ~200 with respect to the previous observation performed about 4.5 yr earlier, and a drop of ~ 135 with respect to its historical flux. Despite the huge X-ray variation, the UV flux remains constant producing a very significant steepening of the optical to X-ray slope αox from -1.56 to -2.44, making PHL 1092 one of the most extreme X-ray weak quasars. The similarity in the soft X-ray spectral shape between the present and previous observations, together with the persistent UV flux and the lack of any dramatic change in the optical spectrum, suggests that an absorption event is not likely to be the origin of the observed variation. If absorption is ruled out, the sudden X-ray weakness of PHL 1092 must be produced by a transient significant weakening or disruption of the X-ray emitting corona.

AB - We report a dramatic variability event in the X-ray history of the narrow-line quasar PHL 1092 (z = 0.396). Our latest 2008 XMM-Newton observation reveals a flux drop of ~200 with respect to the previous observation performed about 4.5 yr earlier, and a drop of ~ 135 with respect to its historical flux. Despite the huge X-ray variation, the UV flux remains constant producing a very significant steepening of the optical to X-ray slope αox from -1.56 to -2.44, making PHL 1092 one of the most extreme X-ray weak quasars. The similarity in the soft X-ray spectral shape between the present and previous observations, together with the persistent UV flux and the lack of any dramatic change in the optical spectrum, suggests that an absorption event is not likely to be the origin of the observed variation. If absorption is ruled out, the sudden X-ray weakness of PHL 1092 must be produced by a transient significant weakening or disruption of the X-ray emitting corona.

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U2 - 10.1111/j.1745-3933.2009.00669.x

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