Resumen
High energy gamma-rays in a strong radiation field can be absorbed by producing electron-positron pairs. Such mechanism has been previously used for studying the propagation of 1015 eV photons in the cosmic-ray background, and of lower energy photons through infrared bakcground. A formalism to address the problem of gamma-ray pair absorption in the radiation field of thermal accretion disks is presented and applied to relevant stellar and AGN examples. The predictions of these models might be within the reach of existing observations. In the specific case of Mk421, the spectral break that the accretion disk should produce is not observed, pointing to TeV emission in a region outside the accretion disk.
