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Title:
A two-phase model for the X-ray emission from Seyfert galaxies
Authors:
Haardt, F.; Maraschi, L.
Affiliation:
AA(Milano, Università, Milan, Italy), AB(Milano, Università, Milan, Italy)
Publication:
Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X), vol. 380, Oct. 20, 1991, p. L51-L54. (ApJL Homepage)
Publication Date:
10/1991
Category:
Astrophysics
Origin:
STI
NASA/STI Keywords:
Accretion Disks, Astronomical Models, Emission Spectra, Seyfert Galaxies, X Ray Spectra, Computational Astrophysics, Galactic Nuclei, Gravitational Effects, Interstellar Magnetic Fields, Magnetic Field Reconnection
DOI:
10.1086/186171
Bibliographic Code:
1991ApJ...380L..51H

Abstract

Attention is given to a two-phase accretion disk model, with emphasis on thermal Comptonization as the basic mechanism for producing the X-ray power-law continuum of Seyfert galaxies within the framework of the new picture of the inner emission region. A substantial fraction, f, of the gravitational power is assumed to be dissipated via buoyancy and reconnection of the magnetic fields in a hot tenuous 'corona' surrounding the disk's main body. Coupled thermal balance equations for the two phases yield the temperature of the hot phase and the slope of the Comptonized component self-consistently as a function of f and tau, the optical depth of the hot phase. It is found that for f approximately equal to 1 and tau less than 1, the temperature of the hot phase adjusts so as to maintain alpha approximately equal to 1. For small tau the temperature of the hot phase is sufficient for the production of electron-positron pairs to be important. Pair production contributes to the optical depth and limits the maximum temperature allowed.

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