PHL 1092 as a transient extreme X-ray weak quasar

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dc.creator Gallo, Luigi C.
dc.creator Miniutti, G.
dc.creator Fabian, A. C.
dc.creator Brandt, W. N.
dc.creator Boller, Th.
dc.date.accessioned 2015-04-24T15:17:46Z
dc.date.available 2015-04-24T15:17:46Z
dc.date.issued 2009
dc.identifier.issn 1745-3933
dc.identifier.uri http://library2.smu.ca/xmlui/handle/01/26074
dc.description Publisher's version/PDF en_CA
dc.description.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 [alpha][subscript ox] 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. en_CA
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dc.description.provenance Made available in DSpace on 2015-04-24T15:17:46Z (GMT). No. of bitstreams: 1 Gallo_Luigi_C_article_2009_b.pdf: 294439 bytes, checksum: 82eff41112b92c7036234b7593ab6bdb (MD5) Previous issue date: 2009 en
dc.language.iso en en_CA
dc.publisher Royal Astronomical Society en_CA
dc.publisher Oxford University Press
dc.relation.uri http://dx.doi.org/10.1111/j.1745-3933.2009.00669.x
dc.rights This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society Letters ©: 2009 The Authors ©: 2009 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
dc.subject.lcsh Active galaxies
dc.subject.lcsh X-ray sources, Galactic
dc.title PHL 1092 as a transient extreme X-ray weak quasar en_CA
dc.type Text en_CA
dcterms.bibliographicCitation Monthly Notices of the Royal Astronomical Society Letters 396(1), L85-L89. (2009) en_CA
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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society Letters ©: 2009 The Authors ©: 2009 RAS. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
 
Published Version: http://dx.doi.org/10.1111/j.1745-3933.2009.00669.x
 
 

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