Journal Article

Detection of blueshifted emission and absorption and a relativistic iron line in the X-ray spectrum of ESO 323−G077*

E. Jiménez-Bailón, Y. Krongold, S. Bianchi, G. Matt, M. Santos-Lleó, E. Piconcelli and N. Schartel

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 391, issue 3, pages 1359-1368
Published in print December 2008 | ISSN: 0035-8711
Published online November 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13976.x
Detection of blueshifted emission and absorption and a relativistic iron line in the X-ray spectrum of ESO 323−G077*

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We report on the X-ray observation of the Seyfert 1 galaxy ESO 323−G077 performed with XMM–Newton. The EPIC spectra show a complex spectrum with conspicuous absorption and emission features. The continuum emission can be modelled with a power law with an index of 1.99 ± 0.02 in the whole XMM–Newton energy band, marginally consistent with typical values of type I objects. An absorption component with an uncommonly high equivalent hydrogen column (nH= 5.82+0.12−0.11× 1022cm−2) is affecting the soft part of the spectrum. Additionally, two warm absorption components are also present in the spectrum. The lower ionized one, mainly imprinting the soft band of the spectrum, has an ionization parameter of log U= 2.14+0.06−0.07 and an outflowing velocity of v= 3200+600−200 km s−1. Two absorption lines located at ∼6.7 and ∼7.0 keV can be modelled with the highly ionized absorber. The ionization parameter and outflowing velocity of the gas measured are log U= 3.26+0.19−0.15 and v= 1700+600−400 km s−1, respectively. Four emission lines were also detected in the soft energy band. The most likely explanation for these emission lines is that they are associated with an outflowing gas with a velocity of ∼2000 km s−1. The data suggest that the same gas which is causing the absorption could also being responsible of these emission features. Finally, the XMM–Newton spectrum shows the presence of a relativistic iron emission line likely originated in the accretion disc of a Kerr black hole with an inclination of ∼25°. We propose a model to explain the observed X-ray properties which invokes the presence of a two-phase outflow with cone-like structure and a velocity of the order of 2000– 4000 km s−1. The inner layer of the cone would be less ionized, or even neutral, than the outer layer. The inclination angle of the source would be lower than the opening angle of the outflowing cone.

Keywords: galaxies: active; galaxies: individual: ESO 323−G077; galaxies: nuclei; galaxies: Seyfert; X-rays: galaxies

Journal Article.  8108 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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