We analysed the spectra from the XMM-Newton and the three longest Chandra observations of the Circinus Galaxy, the X-ray brightest, Compton-thick Seyfert 2 galaxy, to derive the physical and morphological parameters of the circumnuclear matter. We compare the line and continuum parameters with extensive calculations performed with the well-known photoionisation code CLOUDY. The line spectrum cannot be explained by a single zone, as three different reflecting regions are required. The first has low ionisation, accounting for the prominent iron K alpha line, and is likely to be identified with the "torus" envisaged in unification models for Seyfert galaxies; a lower limit of 0.05 pc to the distance of this matter from the nucleus has been estimated, using new constraints on the ionisation state of iron (<= FeX). The second zone is moderately ionised and optically thin (tau similar or equal to 0.2), and it accounts for the

Massaro F, Bianchi S, Matt G, D'Onofrio E, & Nicastro F (2006). The properties of the circumnuclear regions in the Circinus galaxy RID B-4804-2010. ASTRONOMY & ASTROPHYSICS, 455(1), 153-159 [10.1051/0004-6361:20054772].

The properties of the circumnuclear regions in the Circinus galaxy RID B-4804-2010

MATT, Giorgio;
2006

Abstract

We analysed the spectra from the XMM-Newton and the three longest Chandra observations of the Circinus Galaxy, the X-ray brightest, Compton-thick Seyfert 2 galaxy, to derive the physical and morphological parameters of the circumnuclear matter. We compare the line and continuum parameters with extensive calculations performed with the well-known photoionisation code CLOUDY. The line spectrum cannot be explained by a single zone, as three different reflecting regions are required. The first has low ionisation, accounting for the prominent iron K alpha line, and is likely to be identified with the "torus" envisaged in unification models for Seyfert galaxies; a lower limit of 0.05 pc to the distance of this matter from the nucleus has been estimated, using new constraints on the ionisation state of iron (<= FeX). The second zone is moderately ionised and optically thin (tau similar or equal to 0.2), and it accounts for the
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11590/132530
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