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Session 31 - Black Holes.
Oral session, Monday, January 15
Corte Real, Hilton

[31.04] High-Energy Spectral Complexity from Thermal Gradients in Black Hole Atmospheres

J. G. Skibo (NRL), C. D. Dermer (NRL)

We show that Comptonization in thermally stratified black-hole accretion plasmas can give rise to a spectral hardening above \sim 10 keV as observed in the X-ray spectra of black holes and which is generally attributed to reprocessing of the incident continuum by cold optically thick matter. The presence of the hardening in the incident continuum results in Fe K\alpha line emission with an equivalent width larger than that produced by a simple power law continuum. We also show that energy equipartition in two-temperature plasmas naturally produces power law X-ray spectra with energy indices \alpha\simeq0.9 below 10 keV and cut offs near \sim100 keV as are observed in the spectra of Seyfert AGNs. We model the high energy spectra from black holes in a self-consistent manner including primary and reprocessed radiation from the accretion disk in addition to the Comptonized emission from the thermally stratified accretion plasma.

Program listing for Monday