The X-ray spectrum and variability of Markarian 421.
Abstract
The X-ray bright BL Lac object Markarian 421 (Mrk 421) was observed by Exosat four times over a period of 6 days in February 1984. The source exhibited a very soft power-law X-ray spectrum (photon spectral index is about 2.8) with an extremely low intrinsic column density (less than or equal to 10 to the 20th/sq cm). Significant X-ray variability (about 40 percent) was apparent on a time scale of the order of a day with an indication of a softening of the X-ray spectrum as the source flux decreased. The relatively rapid X-ray variability and overall (radio to X-ray) spectrum of Mrk 421 are discussed in terms of the synchrotron self-Compton model. A high degree of relativistic beam is not a requirement for this source.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 1986
- DOI:
- 10.1093/mnras/219.1.39
- Bibcode:
- 1986MNRAS.219...39W
- Keywords:
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- Bl Lacertae Objects;
- Variability;
- X Ray Sources;
- Exosat Satellite;
- Light Curve;
- X Ray Spectra;
- Astrophysics