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Session 36 - Active Galactic Nuclei.
Display session, Tuesday, June 09
Atlas Ballroom,

[36.06] A Grid of Non-LTE Models and Theoretical Spectra of AGN Accretion Disks

I. Hubeny (NASA/GSFC), O. Blaes (U. California, Santa Barbara), E. Agol (Johns Hopkins U.)

We present a grid of non-LTE models of the vertical structure and emergent spectra of accretion disks around supermassive Kerr black holes. For computing the disk structure, the interaction of radiation and matter is treated self-consistently, taking into account departures from LTE for calculating both the disk structure and the radiation field.

The basic parameters of the system are the black hole mass, M, the mass accretion rate, \dotM, the angular momentum (rotation) of the black hole (a/M), and the chemical composition of the disk. The viscosity is parameterized through a parameter \alpha which describes the vertically-averaged viscous stress, two power-law exponents \zeta_0 and \zeta_1, and the division point m_d between these two forms. The disk structure and emergent radiation is sensitive mainly to the values of \alpha, while the other parameters influence the disk structure to a much lesser extent.

We have constructed a grid of non-LTE disk models for M = 1, 2, 4, 8, 10, 16, and 32 (in units of 10^9 M_ødot), and the mass accretion rates 1, 2, 4, 8, 10, 16 M_ødot/yr, for all combinations of these parameters which yield the total luminosity below the Eddington limit. In the present study, we have considered only H-He models with a solar helium abundance. We have assumed the maximum stable rotation of the black hole, a/M=0.998, and \alpha was set to 0.01. Each disk was divided into a set of 20 - 25 concentric annuli covering the region between radii 1.3 to 50 gravitational radii, R_g = G M/c^2. These annuli provide all emergent UV and harder disk radiation, and most of its optical radiation. The disk structure (including general relativistic effects) was computed with the code TLUSDISK; the local spectra of the annuli by program SYNSPEC; and the integrated spectrum of the disk taking into account all general relativistic effects was done by program KERRTRANS (Agol 1997).

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