Journal Article

A reflection origin for the soft and hard X-ray excess of Ark 120

E. Nardini, A. C. Fabian, R. C. Reis and D. J. Walton

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 2, pages 1251-1261
Published in print January 2011 | ISSN: 0035-8711
Published online December 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17518.x
A reflection origin for the soft and hard X-ray excess of Ark 120

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Over the last few years, several models have been proposed to interpret the widespread soft excess observed in the X-ray spectra of type 1 active galactic nuclei (AGN). In particular, reflection from the photoionized accretion disc blurred by relativistic effects has proven to be successful in reproducing both the spectral shape and the variability pattern of many sources. As a further test to this scenario, we present the analysis of a recent ∼100 ks long Suzaku observation of Arakelian 120, a prototypical ‘bare’ Seyfert 1 galaxy in which no complex absorption system is expected to mimic a soft excess or mask the intrinsic properties of this key component. We show that a reflection model allowing for both warm/blurred and cold/distant reprocessing provides a self-consistent and convincing interpretation of the broad-band X-ray emission of Ark 120, also characterized by a structured iron feature and a high-energy hump. Although warm absorbers, winds/outflows and multiple Comptonizing regions may play significant roles in sources with more spectral complexity, this case study adds evidence to the presence of blurred disc reflection as a basic component of the X-ray spectra of type 1 AGN.

Keywords: galaxies: active; galaxies: individual: Ark 120; X-rays: galaxies

Journal Article.  7992 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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