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F. Yuan (Physics Department, Purdue University), A. Zdziarski (N. Copernicus Astronomical Center)
We investigate accretion disc models for the X-ray emission of Seyfert-1 galaxies and the hard state of black-hole X-ray binaries. We concentrate on two hot accretion disc models: advection-dominated accretion flow (ADAF) and recently found luminous hot accretion flow (LHAF) which is an extension of ADAF above its critical accretion rate. We solve for the global solution of both ADAF and LHAF to obtain the electron temperature, T\rm e, and Thompson optical depth, \tau, at the radius where most of the radiation comes from. Two kinds of electron energy equations are adopted. In one, only synchrotron and bremsstrahlung radiation and their Comptonization are considered. The other is parameterized by a constant Compton parameter to model the case in which thermal Comptonization of external soft photon is important. We compare the calculated T\rm e and \tau with the observational values obtained by fitting the average spectra of Seyfert-1 galaxies and black-hole binaries using thermal Comptonization model. We find that the most favoured model is an LHAF with parameterized electron energy equation, with ADAFs predicting too high T\rm e. This work was supported in part by NASA grants NAG5-9998 and NAG5-10780 and PBZ-KBN-054/P03/2001.
The author(s) of this abstract have provided an email address for comments about the abstract: fyuan@physics.purdue.edu
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.