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Driving extreme variability: Measuring the evolving coronae and evidence for jet launching in AGN

Wilkins, D. R. (2016) Driving extreme variability: Measuring the evolving coronae and evidence for jet launching in AGN. Astronomische Nachrichten, 337 (4-5). pp. 557-562. ISSN 0004-6337. doi:10.1002/asna.201612347.

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Relativistically blurred reflection from the accretion disc provides a powerful probe of the extreme environments close to supermassive black holes; the inner regions of the accretion flow and the corona that produces the intense X-ray continuum. Techniques by which the geometry and extent of the corona can be measured through the observed X-ray spectrum are reviewed along with the evolution in the structure of the corona that is seen to accompany variations in the X-ray luminosity both on long and short timescales. Detailed analyses of the narrow line Seyfert 1 galaxies Mrk 335 and 1H 0707-495, over observations with XMM-Newton as well as Suzaku and NuSTAR spanning nearly a decade reveal that increases in the X-ray luminosity coincide with an expansion of the corona to cover a larger area of the inner accretion disc. Underlying this long timescale variability lie more complex patterns of behaviour on short timescales. Flares in the X-ray emission during a low flux state of Mrk 335 observed in 2013 and 2014 are found to mark a reconfiguration of the corona while there is evidence that the flares were caused by a vertical collimation and ejection of coronal material, reminiscent of an aborted jet-launching event. Measurements of the corona and reflecting accretion disc are combined to infer the conditions on the inner disc that lead to the flaring event.

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Additional Information:© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Issue or Number:4-5
Record Number:CaltechAUTHORS:20160527-092024172
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Official Citation:Wilkins, D. R. (2016), Driving extreme variability: Measuring the evolving coronæ and evidence for jet launching in AGN. Astron. Nachr., 337: 557–562. doi: 10.1002/asna.201612347
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67431
Deposited By: Joy Painter
Deposited On:27 May 2016 16:38
Last Modified:11 Nov 2021 00:32

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