ROSAT PSPC Observations of Seyfert 2 Galaxies
Abstract
We present soft x-ray spectra of three Seyfert 2 galaxies obtained with the ROSAT PSPC. These spectra have the following properties: 1) For NGC 5506 and MCG-5-23-16 most of the flux occurs at energies greater than 1 keV and is associated with the hard x-ray continuum. Both sources suffer a significant photoelectric cut-off at ~ 1 keV, with column densities several times 10(22) cm(-2) . The third source, MKN 348, has very little flux in the ROSAT band, suggesting a photoelectric cut-off at higher energies, in agreement with GINGA observations. 2) In all three objects, x-rays are seen below the photoelectric cut-off at above the rate expected from a source with the hard powerlaw spectrum suffering a uniform column cut-off. This result indicates the presence of an additional x-ray component at soft energies (i.e. a \lq`soft excess\rq\rq ). The flux of this component is ~ 1 % that of the hard x-ray continuum. 3) In MCG-5-23-16 and MKN 348, this soft component is well-described by a powerlaw with a considerably steeper index than the hard x-ray continuum. No steep component is seen in NGC 5506, although additional absorption from the edge-on host galaxy would make such a detection difficult. We will discuss the implications these observations have for the molecular torus model and the scattering region in Seyfert 2 galaxies.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1992
- Bibcode:
- 1992AAS...181.9804W