The intrinsic emission of Seyfert galaxies observed with BeppoSAX/PDS I. Comparison of the average spectra of the three classes of Seyfert Galaxies

TL;DR

This study analyzes the hard X-ray spectra of different Seyfert galaxy classes to understand their intrinsic emission and test unified models, revealing differences in spectral features such as high energy cutoff and reflection components.

Contribution

It provides the first comparative analysis of average hard X-ray spectra across Seyfert 1, 1.5, and 2 galaxies, highlighting spectral differences relevant to unified models.

Findings

Seyfert 1 galaxies show a high energy cutoff in their spectrum.

Seyfert 2 galaxies lack a high energy cutoff and may have stronger reflection components.

Seyfert 1.5 galaxies exhibit ambiguous spectral features, combining properties of Sy 1 and Sy 2.

Abstract

We present a study of the hard X-ray spectrum (>15 keV) of different classes of Seyfert galaxies observed with BeppoSAX/PDS. Using hard X-ray data, we avoid absorption effects modifying the Seyfert emission and have direct access to the central engine of these sources. The aim of this study is first to characterize the general properties of the hard X-ray spectrum of Seyfert 1, 1.5 and 2 galaxies and secondly to compare their intrinsic emission to test unified models according to which all the classes have the same nucleus. We compute the average spectrum of 14 Sy 1, 9 Sy 1.5 and 22 Sy 2 galaxies observed by the PDS (15-136 keV). The average spectrum of Sy 1 differs from that of Sy 2, the first requiring the presence of a high energy cutoff which is absent in the second. We also show that the reflection component is possibly more important in the Sy 2 emission. The nature of Sy 1.5 galaxies is ambiguous as they have a negligible reflection component (like Sy 1) and do not require a cutoff (like Sy 2)