The High-Energy Spectrum of Hot Accretion Disks

A hot, two-temperature accretion disk can be a strong γ-ray and relativistic particle source. This occurs when the accretion rate is high enough -- M/ M ≥ 3 X 10^-9 α γr^-1 for a canonical Kerr black hole-due to the high ion temperature in the inner disk. We present detailed photon and particle spectra for specific disk models. The predicted γ-ray flux is as high as 10% of the bolometric luminosity in sub-Eddington models. Most of the γ-radiation is continuous, due to the π^0 decay, emitted around 100 MeV but degraded to a few MeV in optically thick models. Spectral lines, due to positon annihilation or to excited nuclei, provide only a small amount of the primary γ-ray luminosity. The energy flux in - 35 MeV pairs is comparable to the γ-ray luminosity; Penrose effects provide a smaller number of - I Ge V pairs. Applications of the model both to galactic and extragalactic sources are discussed. Both the galactic center y-ray source and the extragalactic y-ray background (if it is due to discrete sources) may be due to this type of model