Probing the geometry and motion of AGN coronae through accretion disc emissivity profiles

Abstract

To gain a better understanding of the inner disc region that comprises active galactic nuclei it is necessary to understand the pattern in which the disc is illuminated (the emissivity profile) by X-rays emitted from the continuum source above the black hole (corona). The differences in the emissivity profiles produced by various corona geometries are explored via general relativistic ray tracing simulations. Through the analysis of various parameters of the geometries simulated it is found that emissivity profiles produced by point source and extended geometries such as cylindrical slabs and spheroidal coronae placed on the accretion disc are distinguishable. Profiles produced by point source and conical geometries are not significantly different, requiring an analysis of reflection fraction to differentiate the two geometries. Beamed point and beamed conical sources are also simulated in an effort to model jet-like coronae, though the differences here are most evident in the reflection fraction. For a point source we determine an approximation for the measured reflection fraction with the source height and velocity. Simulating spectra from the emissivity profiles produced by the various geometries produce distinguishable differences. Overall spectral differences between the geometries do not exceed 15 per cent in the most extreme cases. It is found that emissivity profiles can be useful in distinguishing point source and extended geometries given high quality spectral data of extreme, bright sources over long exposure times. In combination with reflection fraction, timing, and spectral analysis we may use emissivity profiles to discern the geometry of the X-ray source.

15 pages, 12 figures. Accepted for publication in MNRAS

References in corpus (7)

• Constraining Black Hole Spin Via X-ray Spectroscopy
• Driving extreme variability: The evolving corona and evidence for jet launching in Markarian 335
• The Comptonisation of accretion disc X-ray emission: Consequences for X-ray reflection and the geometry of AGN coronae
• Suzaku observations of Mrk 335: Confronting partial covering and relativistic reflection
• Caught in the act: Measuring the changes in the corona that cause the extreme variability of 1H 0707-495
• Gravitational effects on the high energy emission of accreting black holes
• An XSPEC model to explore spectral features from black-hole sources - II. The relativistic iron line in the lamp-post geometry

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• Characterising continuum variability in the radio-loud narrow-line Seyfert 1 galaxy IRAS 17020+4544
• On the Calculation of the Fe K-alpha Line Emissivity of Black Hole Accretion Disks