paper

An X-ray view of absorbed INTEGRAL AGN

arXiv:0801.4675 · doi:10.1051/0004-6361:20078319

Abstract

Aims. We present a 0.2--200 keV broad-band study of absorbed AGN observed with INTEGRAL, XMM-Newton, Chandra and ASCA to investigate the continuum shape and the absorbing/reflecting medium properties. Methods. The sources are selected in the INTEGRAL AGN sample to have a 20--100 keV flux below 8 $\flux$ (5 mCrab), and are characterized by a 2--10 keV flux in the range (0.8--10) $\flux$. The good statistics allow us a detailed study of the intrinsic and reflected continuum components. In particular, the analysis performed on the combined broad-band spectra allow us to investigate the presence of Compton reflection features and high energy cut-off in these objects. Results. The column density of the absorbing gas establishes the Compton thin nature for three sources in which a measure of the absorption was still missing. The Compton thin nature of all the sources in this small sample is also confirmed by the diagnostic ratios F$x/F[OIII]. The Compton reflection components we measure, reflection continuum and iron line, are not immediately compatible with a scenario in which the absorbing and reflecting media are one and the same, i.e. the obscuring torus. A possible solution is that the absorption is more effective than reflection, e.g. under the hypothesis that the absorbing/reflecting medium is not uniform, like a clumpy torus, or that the source is observed through a torus with a very shallow opening angle. The high energy cut-off (a lower limit in two cases) is found in all sources of our sample and the range of values is in good agreement with that found in type 1 Seyfert galaxies. At lower energies there is clear evidence of a soft component (reproduced with a thermal and/or scattering model), in six objects.

Accepted for publication in Astronomy and Astrophysics

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