Journal Article

1H 0707−495 in 2011: an X-ray source within a gravitational radius of the event horizon

A. C. Fabian, A. Zoghbi, D. Wilkins, T. Dwelly, P. Uttley, N. Schartel, G. Miniutti, L. Gallo, D. Grupe, S. Komossa and M. Santos-Lleó

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 419, issue 1, pages 116-123
Published in print January 2012 | ISSN: 0035-8711
Published online December 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19676.x
1H 0707−495 in 2011: an X-ray source within a gravitational radius of the event horizon

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The narrow-line Seyfert 1 Galaxy 1H 0707−495 went into a low state from 2010 December to 2011 February, discovered by a monitoring campaign using the X-Ray Telescope on the Swift satellite. We triggered a 100 ks XMM–Newton observation of the source in 2011 January, revealing the source to have dropped by a factor of 10 in the soft band, below 1 keV, and a factor of 2 at 5 keV, compared with a long observation in 2008. The sharp spectral drop in the source usually seen around 7 keV now extends to lower energies, below 6 keV in our frame. The 2011 spectrum is well fitted by a relativistically blurred reflection spectrum similar to that which fits the 2008 data, except that the emission is now concentrated solely to the central part of the accretion disc. The irradiating source must lie within 1 gravitational radius of the event horizon of the black hole, which spins rapidly. Alternative models are briefly considered, but none has any simple physical interpretation.

Keywords: black hole physics; galaxies: individual: 1H 0707−495; X-rays: galaxies

Journal Article.  5379 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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