Iron Kα emission in type-I and type-II active galactic nuclei

• Published in: Monthly notices of the Royal Astronomical Society 2014-07, Vol.441 (4), p.3622-3633
• Main Authors: Ricci, C., Ueda, Y., Paltani, S., Ichikawa, K., Gandhi, P., Awaki, H.
• Format: Article
• Language: English
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stu735

The narrow Fe Kα line is one of the main signatures of the reprocessing of X-ray radiation from the material surrounding supermassive black holes, and it has been found to be omnipresent in the X-ray spectra of active galactic nuclei (AGN). In this work, we study the characteristics of the narrow Fe Kα line in different types of AGN. Using the results of a large Suzaku study, we find that Seyfert 2s have on average lower Fe Kα luminosities than Seyfert 1s for the same 10–50 keV continuum luminosity. Simulating dummy Seyfert 1s and Seyfert 2s populations using physical torus models of X-ray reflected emission, we find that this difference can be explained by means of different average inclination angles with respect to the torus, as predicted by the unified model. Alternative explanations include differences in the intensities of Compton humps, in the photon index distributions or in the average iron abundances. We show that the ratio between the flux of the broad and narrow Fe Kα line in the 6.35–6.45 keV range depends on the torus geometry considered, and is on average