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Thermal Or Non–Thermal X–Rays From AGNs?

Published online by Cambridge University Press:  19 July 2016

Gabriele Ghisellini  and
Francesco Haardt
Gabriele Ghisellini
Affiliation:
Osservatorio di Torino, Strada Osservatorio 20, 10025 Torino, Italy
Francesco Haardt
Affiliation:
ISAS/SISSA, Via Beirut 2–4, 34013 Trieste, Italy

Abstract

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Recent data from OSSE on CGRO and SIGMA on GRANAT challenge the non-thermal interpretation of the origin of the high energy emission of AGNs, showing that the hard X-ray spectra of several Seyfert AGN are steep like those of Galactic black hole candidates. Thermal models are therefore favoured. Two–phase models, in which a hot corona is placed above a relatively cold accretion disk can account for the observed X–ray spectra and the correlated variability in the UV and X–ray bands. Cold matter, both in the vicinity of the nucleous, and located further away in the torus surrounding the nucleous, may modify substantially the spectrum with important consequences on the expected variability and spectral shape.

Keywords

X–raysActive Galactic NucleiComptonization
Type
Multi-wavelength Continuum Emission of AGN
Information
Symposium - International Astronomical Union , Volume 159: Multi-Wavelength Continuum Emission of AGN , 1994 , pp. 33 - 36
Copyright
Copyright © Kluwer 1994 

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