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摘要
Aims. We present a 0.2-200 keV broadband study of absorbed Active Galactic Nuclei (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 x 10(-11) erg cm(-2) s(-1) (5 mCrab), and are characterized by a 2-10 keV flux in the range (0.8-10) x 10(-11) erg cm(-2) s(-1). The high quality of data allow us a detailed study of the intrinsic and reflected continuum components. In particular, the analysis performed on the combined broadband spectra allow us to investigate the presence of Compton reflection features and high energy cuto. 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 cuto. (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.
- 出版日期2008-6
