Accretion-disk models of quasars and active galactic nuclei

Calculations of the spectra of black-hole accretion disks that may power quasars and active galactic nuclei are presented. The disk is geometrically thin and optically thick. The effects of electron-scattering opacity and general-relativistic corrections at different disk inclinations on the observed spectra are included. Low-gravity non-LTE stellar atmospheres are used to approximate the locally emerging flux on the disk surface in order to account for the dominance of electron-scattering opacity. Alternative disks with a series of blackbodies at different temperatures are also modeled. Both Kerr and Schwarzschild geometries are considered. The relativistic correction is much more significant in the Kerr case than that in the Schwarzschild case. The atmosphere disk predicts a spectrum harder than that of the blackbody disk. When the disk is viewed at higher inclinations, the apparent disk spectrum also becomes harder