What is the origin of the soft excess in active galactic nuclei?

Sobolewska, M.A.; Done, C.

doi:10.1111/j.1365-2966.2006.11117.x

What is the origin of the soft excess in active galactic nuclei?

Sobolewska, M.A.; Done, C.

Authors

M.A. Sobolewska

Professor Christine Done chris.done@durham.ac.uk
Professor

Abstract

We investigate the nature of the soft excess below 1 keV observed in active galactic nuclei. We use the XMM–Newton data of the low-redshift, optically bright quasar, PG 1211+143, and we compare it with the narrow-line Seyfert 1 galaxy, 1H 0707−495, which has one of the strongest soft excesses seen. We test various ideas for the origin of the soft X-ray excess, including a separate spectral component (for example, low-temperature Comptonized emission), a reflection-dominated model, or a complex absorption model. All three can give good fits to the data, and χ2-fitting criteria are not sufficient to discriminate among them. Instead, we favour the complex absorption model on the grounds that it requires less extreme parameters. In particular, the geometry appears to be more physically plausible as the reflected component in the smeared absorption model is no longer dominant, and relativistic distortions, while still clearly present, are not tremendously larger than expected for a disc around a Schwarzchild black hole.

Citation

Sobolewska, M., & Done, C. (2007). What is the origin of the soft excess in active galactic nuclei?. Monthly Notices of the Royal Astronomical Society, 374(1), 150-158. https://doi.org/10.1111/j.1365-2966.2006.11117.x

Journal Article Type	Article
Publication Date	2007-01
Deposit Date	Apr 16, 2008
Publicly Available Date	Aug 11, 2014
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Electronic ISSN	1365-2966
Publisher	Royal Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	374
Issue	1
Pages	150-158
DOI	https://doi.org/10.1111/j.1365-2966.2006.11117.x
Keywords	Accretion, accretion discs; Atomic processes, Galaxies: active; Galaxies: individual: PG 1211+143; Galaxies: individual: 1H 0707−495; X-rays: galaxies.

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This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2007 The Authors Published on behalf of Royal Astronomical Society. All rights reserved.