Caught in the act: measuring the changes in the corona that cause the extreme variability of 1H 0707−495

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dc.creator Wilkins, D. R.
dc.creator Kara, E.
dc.creator Fabian, A. C.
dc.creator Gallo, Luigi C.
dc.date.accessioned 2018-04-10T20:12:12Z
dc.date.available 2018-04-10T20:12:12Z
dc.date.issued 2014-09-21
dc.identifier.issn 0035-8711
dc.identifier.uri http://library2.smu.ca/handle/01/27409
dc.description Publisher's Version/PDF
dc.description.abstract The X-ray spectra of the narrow-line Seyfert 1 galaxy, 1H 0707–495, obtained with XMM–Newton, from time periods of varying X-ray luminosity are analysed in the context of understanding the changes to the X-ray emitting corona that lead to the extreme variability seen in the X-ray emission from active galactic nuclei (AGN). The emissivity profile of the accretion disc, illuminated by the X-ray emitting corona, along with previous measurements of reverberation time lags, is used to infer the spatial extent of the X-ray source. By fitting a twice-broken power-law emissivity profile to the relativistically broadened iron Kα fluorescence line, it is inferred that the X-ray emitting corona expands radially, over the plane of the accretion disc, by 25 to 30 per cent as the luminosity increases, contracting again as the luminosity decreases, while increases in the measured reverberation lag as the luminosity increases would require also variation in the vertical extent of the source above the disc. The spectrum of the X-ray continuum is found to soften as the total X-ray luminosity increases and we explore the variation in reflected flux as a function of directly observed continuum flux. These three observations combined with simple, first-principles models constructed from ray-tracing simulations of extended coronæ self-consistently portray an expanding corona whose average energy density decreases, but with a greater number of scattering particles as the luminosity of this extreme object increases. en_CA
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dc.description.provenance Made available in DSpace on 2018-04-10T20:12:12Z (GMT). No. of bitstreams: 1 Wilkins_D_article_2014_b.pdf: 716786 bytes, checksum: 37665669b5482cd5615f06d3c1ccdfc0 (MD5) Previous issue date: 2014-06-24 en
dc.language.iso en en_CA
dc.publisher Oxford University Press en_CA
dc.relation.uri http://dx.doi.org/10.1093/mnras/stu1273
dc.rights This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
dc.subject.lcsh Accretion (Astrophysics)
dc.subject.lcsh Black holes (Astronomy)
dc.subject.lcsh Active galactic nuclei
dc.subject.lcsh X-ray sources, Galactic
dc.title Caught in the act: measuring the changes in the corona that cause the extreme variability of 1H 0707−495 en_CA
dc.type Text en_CA
dcterms.bibliographicCitation Monthly Notices of the Royal Astronomical Society 443(3), 2746-2756. (2014) en_CA
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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
 
Published Version: http://dx.doi.org/10.1093/mnras/stu1273
 
 

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