Discovery of a strong soft X-ray excess in MKN 335 - evidence for an accretion disc ?
Abstract
Exosat observations of Mkn 335 reveal a hard power-law spectrum above about 1 keV, typical for Seyfert 1 galaxies, but with unusually strong variability on time-scales of about 1-2 hr. In addition, an intense soft X-ray component is found to dominate the overall spectrum of Mkn 335 below about 0.6 keV. Both soft and hard components increased in strength by a factor about 6 between 1983 November and 1984 December. These observations are discussed in terms of models in which an accretion disc feeds a central massive black hole. It is found that radiation pressure only allows a thermal origin for the soft X-radiation if the black hole mass is less than about 10 to the 7th solar masses, as suggested also by the observed variability time-scale.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 1987
- DOI:
- 10.1093/mnras/224.2.443
- Bibcode:
- 1987MNRAS.224..443P
- Keywords:
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- Accretion Disks;
- Astronomical Spectroscopy;
- Black Holes (Astronomy);
- Seyfert Galaxies;
- Spaceborne Astronomy;
- X Ray Spectra;
- Astronomical Models;
- Exosat Satellite;
- Radiation Pressure;
- Variability;
- Astrophysics