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Title: Anisotropic X-ray emission in active galactic nucleus accretion discs
Authors: Nayakshin, Sergei
First Published: 1-Mar-2007
Publisher: Royal Astronomical Society (RAS)
Citation: Monthly Notices of the Royal Astronomical Society: LETTERS, 2007, 376 (1)
Abstract: Straightforward models of X-ray reflection in the inner region of accretion discs predict that the primary X-ray flux and the flux reflected off the surface of the disc should vary together, albeit with a short light traveltime delay. Most of the observations, however, show that the X-ray flux can vary while the reflected features remain constant. Here we propose a simple explanation for this. In all likelihood, the emission of a moderately optically thick magnetic flare atop an accretion disc is anisotropic. A constant energy release rate in a flare will appear to produce a variable X-ray flux as the flare rotates with the accretion disc anchoring the magnetic tube. The reflector, on the other hand, receives a constant X-ray flux from the flare. Since the reflected emission is azimuthally symmetric, the observer will see a roughly constant reflected flux (neglecting relativistic effects). The model does not produce quasi-periodic oscillations if magnetic flux tubes are sheared out faster than they complete one orbit.
DOI Link: 10.1111/j.1745-3933.2007.00279.x
ISSN: 1745-3933
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2007 the authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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