ASCAObservations of Type 2 Seyfert Galaxies. III. Orientation and X‐Ray Absorption

We discuss the spectral properties of a sample of type-2 Seyfert galaxiesbased upon the analysis of \asca data. In this paper we consider the sourcesfor which the X-ray spectra appear to be dominated by the nuclear continuum,transmitted through a large column of absorbing material. We find that bothSeyfert-2 galaxies and NELGs show iron K$\alpha$ line profiles indicative ofreprocessing of nuclear X-rays in a face-on accretion disk. Such line profilesare also observed in Seyfert-1 galaxies. This result is contrary to unificationmodels, which would predict the inner regions of Seyfert-2 galaxies to beobserved edge-on. This raises some questions as to the orientation of thecircumnuclear absorber. If the observed differences between Seyfert type-1 andtype-2 galaxies, and NELGs are not due to differences in the orientation of theabsorbing material, then we suggest that differences in dust composition andgrain size, and in the density of the circumnuclear gas could be of primaryimportance.Comment: 28 pages, 3 figures. LaTeX with encapsulated postscript. To appear in the Astrophysical Journa