Escape of TeV gamma rays from anisotropic thermal photon fields in active galactic nuclei

We calculate the optical depth of TeV gamma-rays that result from the anisotropic IR-UV thermal radiation of the alpha-disk model proposed by Shakura & Sunyaev. Our calculations yield the dependences of the optical depth of high-energy gamma-rays on the disk parameters (i.e., alpha, M(8), and M(26)), photon energy, and Phi, the angle between the propagation direction and the rotation axis of the accretion disk. Our results indicate that TeV gamma-rays can escape more easily from the central engine with lower values of alpha (less than or similar to 0.01) and Phi. We conclude that the optical depth of TeV gamma-rays in the anisotropic thermal radiation held places certain constraints on the possible values of the parameter a and the position of the emission region.