A Soft X-Ray Flare in the Seyfert 1 Galaxy Markarian 335
Abstract
Einstein HRI and MPC observations spanning 11 90 minute orbits in 1981 January showed that the Seyfert 1 galaxy Mrk 335 exhibited erratic X-ray activity on all time scales of ~6000-60,000 s. The HRI data very clearly show about 30% decrease in the soft (~0.7 keV) X-ray flux ("dip") followed immediately by a steep increase ("flare") in which the intensity changed by a factor of about 2.5. Both events have time scales of one to two orbits. Much weaker variations in the MPC (1.2-7.0 keV) flux were correlated with the soft X-ray flare. The ratio of total MPC count rate to HRI count rate, i.e., the X-ray "hardness," rose during the dip and then fell by a factor of 2 during the flare. We also find that the time-averaged spectral index of Mrk 335 measured by the MPC to be α_MPC_ = 1.25 +/- 0.19. In addition, a comparison of the HRI and MPC data show that an additional soft X-ray flux component above that expected from the MPC data is very likely to be present. The observed variations in the X-rays, coupled with data from other spectral regions, are used to argue that the soft X-rays may originate near the inner edge (r< 3 x 10^14^ cm) of an accretion disk around a black hole of mass 10^7^-10^8^ M_sun_. Emission from a hot confining medium around the optical line clouds is ruled out. The relatively steady hard X-ray spectrum is consistent with an extrapolation of the infrared/optical power law, and could be direct synchrotron or synchrotron self-Compton scattered flux in a region of size similar to that responsible for the soft X-ray flare.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1988
- DOI:
- Bibcode:
- 1988ApJ...331..154L
- Keywords:
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- Accretion Disks;
- Black Holes (Astronomy);
- Markarian Galaxies;
- Seyfert Galaxies;
- Stellar Flares;
- X Ray Spectroscopy;
- Compton Effect;
- Line Spectra;
- Radio Sources (Astronomy);
- Astronomy;
- BLACK HOLES;
- GALAXIES: INDIVIDUAL NAME: MARKARIAN 335;
- GALAXIES: SEYFERT;
- RADIATION MECHANISMS;
- X-RAYS: BURSTS