MODIFICATION OF HIGH ENERGY γ-RAY SPECTRUM OF BLAZARS DUE TO INTERNAL AND INTERGALACTIC ABSORPTION

Blazars are effective emitters of γ-rays with spectra extending to GeV and TeV energies. In the case of distant TeV blazars, γ-rays undergo severe absorption due to interactions with diffuse intergalactic radiation fields resulting in significant deformations of the initial (source) spectra. Even for the lowest possible level of the Extragalactic Background Light (EBL), the absorption-corrected γ-ray spectra from some TeV blazars appear unusually hard, which cannot be explained within the standard particle acceleration models of blazars. The simplest and most natural solution of this problem seems to us the realization of internal absorption of γ-rays in narrow (e.g. Planckian type) radiation fields in the immediate vicinity of the γ-ray production region.