An anisotropic illumination model of Seyfert I galaxies

Abstract

We present a new model of accretion disk where the disk luminosity is entirely due to the reprocessing of hard radiation impinging on the disk. The hard radiation itself is emitted by a hot point source above the disk, that could be physically realized by a strong shock terminating an aborted jet. This hot source contains ultra-relativistic leptons scattering the disk soft photons by Inverse Compton (IC) process. Using simple formula to describe the IC process in an anisotropic photon field, we derive a self-consistent solution in the Newtonian geometry, where the angular distribution of soft and hard radiation, and the radial profile of the disk effective temperature are determined in a univocal way. This offers an alternative picture to the standard accretion disk emission law, reproducing individual spectra and predicting new scaling laws that fit better the observed statistical properties. General relativistic calculations are also carried out. It appears that differences with the Newtonian case are weak, unless the hot source is very close to the black hole.