Driving Extreme Variability: Measuring the Changing Characteristics of the X-ray Emitting Coronae in AGN
Abstract
Through detailed analysis of the reflection of the X-ray continuum from the accretion disc, it is possible to probe the innermost structures right down to the innermost stable circular orbit and event horizon around the supermassive black holes in AGN. By measuring the emissivity profile of the accretion disc, that is its pattern of illumination by the coronal X-ray source, along with reverberation time lags between variability in the X-ray continuum and reflection, it has proven possible to measure the geometry and spatial extend of the corona that produces the X-ray continuum when the observed data are combined with insight gained from general relativistic ray tracing simulations.We conducted detailed analysis of both the X-ray continuum and its reflection from the accretion disc during periods of high and low X-ray flux drawn from long observations of the narrow line Seyfert 1 galaxy, 1H0707-495, totalling more than 1.3Ms with XMM Newton, as well as during the course of an X-ray flare in another narrow line Seyfert 1 galaxy, Markarian 335, observed in 2013 by Suzaku.These observations allow us to trace, for the first time, from observations, the evolution of the X-ray emitting corona that gives rise to the extreme variability seen in the X-ray emission from AGN. We detect expansion in the corona as well as variations in its energetics as the X-ray flux increases, which gives us insight into the physical processes by which energy is liberated from black hole accretion flows and allows observational constraints to be placed upon theoretical models of black hole accretion flows and associated coronae.
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1430002W