Non-LTE Models and Theoretical Spectra of Accretion Disks in Active Galactic Nuclei II. Vertical Structure of the Disk

摘要

We have calculated several representative models of vertical structure of anaccretion disk around a supermassive Kerr black hole. The interaction ofradiation and matter is treated self-consistently, taking into accountdepartures from LTE for calculating both the disk structure and the radiationfield. The structural equations are described in detail, and variousapproximations are discussed. We have demonstrated that departures from LTE arevery important for determining the disk structure, even at the midplane, aswell as the emergent radiation, particularly for hot and electron--scattering--dominated disks. We have shown that at least for the disk parameters studied inthis paper, NLTE effects tend to reduce the value of the Lyman jump withrespect to the LTE predictions, regardless whether LTE predicts an emission orabsorption jump. We have studied the effects of various values of viscosity onthe model structure and predicted spectral energy distribution. The viscosityis parameterized through a parameter $lpha_0$ which describes thevertically-averaged viscous stress, two power-law exponents $zeta_0$ and$zeta_1$, and the division point $m_{d}$ between these two forms. The diskstructure and emergent radiation is sensitive mainly to the values of$lpha_0$, while the other parameters influence the disk structure to a muchlesser extent. However, although the detailed shape of the predicted spectrumis sensitive to adopted value of $lpha_0$, the overall appearance of thespectrum is quite similar.