X-Ray Emitting-Absorbing Media in Seyfert 1 Galaxies

Abstract

Seyfert galaxies have been shown to exhibit a large varietyof features in their X-ray spectra from which the environment of thecentral engine can lie deduced. We focus on the two following aspects:the Warm Absorber, mainly responsible of the soft X-ray properties.and the reprocessing/reflecting plasma medium at the origin of the ironKα fluorescent line. The physical parameters and the location of theso-called Warm Absorber (WA), a photoionized medium along the lineof sight to the nuclear region, are more strongly constrained by opticalcoronal lines than by the oxygen edges observed in the soft X-raysand produced by the WA. The photoionization models atso predict theintensities of the X-ray (-mission lines which are going to be detectedwith the new generation of X-ray satellites. An alternative model to therelativistic accretion disc is proposed to explain the profile of the X-rayiron Kα line observed in the Seyfert 1. This line can be formed in theframework of a quasi-spherical accretion of optically thick clouds. Anoptically thick photoionization code coupled with a Monte-Carlo codehas been developed to compute the entire spectrum from the IR tothe hard X-rays for a dose geometry with a large covering factor. Themultiple Compton reflections allow to reproduce the redshifted broadiron line as detected in several Seyfert 1 galaxies and in MCG-6-30-15.