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2012MNRAS.420.2087D - Mon. Not. R. Astron. Soc., 420, 2087-2101 (2012/March-1)
Broad-band study of hard x-ray-selected absorbed active galactic nuclei.
DE ROSA A., PANESSA F., BASSANI L., BAZZANO A., BIRD A., LANDI R., MALIZIA A., MOLINA M. and UBERTINI P.
Abstract (from CDS):
A high-energy cut-off is found in 30 per cent of the sample, with an average value below 150 keV, suggesting that this feature has to be present in the X-ray spectra of obscured AGN. The hard X-ray selection favours the detection of more obscured sources, with the log NH average value of 23.15 (standard deviation of 0.89). The diagnostic plot NH versus Foss(2–10 keV)/F(20–100 keV) allowed the isolation of the Compton-thick objects, and may represent a useful tool for future hard X-ray observations of newly discovered AGN. We are unable to associate the reflection components (both continuum and Fe line) with the absorbing gas as a torus (as envisaged in the Unified Model), a more complex scenario being necessary. In the Compton-thin sources, a fraction (but not all) of the Fe K line needs to be produced in a gas located closer to the black hole than the Compton-thick torus, and this is possibly associated with the optical broad-line region, responsible also for the absorption. We still need a Compton-thick medium (not intercepting the line of sight) likely associated to a torus, which contributes to the Fe line intensity and produces the observed reflection continuum above 10 keV. The so-called Iwasawa–Taniguchi effect cannot be confirmed with our data. Finally, the comparison with a sample of unobscured AGN shows that type 1 and type 2 (once corrected for absorption) Seyfert are characterized by the same nuclear/accretion properties (luminosity, bolometric luminosity, Eddington ratio), supporting the `unified' view.
Abstract Copyright: 2012 The Authors Monthly Notices of the Royal Astronomical Society2012 RAS
Journal keyword(s): galaxies: active - galaxies: Seyfert - X-rays: galaxies
Simbad objects: 54
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