EXOSAT observations of the Seyfert galaxy NGC 7469; rapid hard X-rayvariability and a soft X-ray excess.
Abstract
The results of a series of EXOSAT observations of the Seyfert 1 (and starburst) galaxy NGC 7469 performed in July 1984 are presented. During one observation, hard X-ray variability by a factor 2 within 5 hr was found, while the soft X-ray intensity remained constant. In addition the spectral data indicate an excess of soft X-ray emission over that expected from extrapolation of the hard X-ray continuum. There is no evidence for any variability of this soft excess. An extranuclear origin associated with the starburst region seems unlikely, as is soft X-ray emission from any hot confining intercloud medium in the Seyfert narrow-line and broad-line regions, due to the high (greater than 5 x 10 to the 43rd erg/s) luminosity involved in this soft excess. However, soft X-ray emission from a hot optically thin wind cannot be excluded. An alternative is an extra soft X-ray component from the compact nucleus itself.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 1986
- DOI:
- 10.1093/mnras/223.1.29P
- Bibcode:
- 1986MNRAS.223P..29B
- Keywords:
-
- Exosat Satellite;
- Seyfert Galaxies;
- X Ray Astronomy;
- Galactic Nuclei;
- Interstellar Matter;
- Spectrum Analysis;
- Starburst Galaxies;
- Supernova Remnants;
- Variability;
- Astrophysics