出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：According to the unified model, the differences observed in different classes of AGN are due to anisotropic obscuration. This implies that in the hard X-rays, at energies where the radiation can pierce the obscuring material, the average spectral characteristics of different classes of AGN should be the same. Here we present a study of the 17–250 keV INTEGRAL IBIS/ISGRI average spectra of Seyfert galaxies, aimed to constrain similarities and possible differences between different classes of AGN. The sample we consists of all the 172 Seyfert galaxies detected by INTEGRAL IBIS/ISGRI at z<0.2 during its first 7 years of observations. Of these, 45 are Seyfert 1s, 31 Seyfert 1.5s, 67 Compton-thin Seyfert 2s, 11 Narrow Line Seyfert 1s, 11 Comptonthick Seyfert 2s, and 9 LINERs. Comparing the average hardX-ray spectra of the different classes, we found that, while the spectra of Seyfert 1s, Seyfert 1.5 and NLS1s are consistent, Comptonthin Seyfert 2 show a clear excess in the 20–60 keV band over the spectrum of Seyfert 1s and Seyfert 1.5s. This excess might be due to an intrinsically stronger reflection component or to a clumpy structure of the absorber in Compton-thin Seyfert 2s.
