Spectral variations of gamma quanta generated by nuclei of active galaxies and quasars in a cascade model

In a cascade model, the observed gamma radiation from the nuclei of active galaxies and quasars is a result of the development of electron-photon cascades, which arise when high energy particles generated in a source travel through the active area of its X-ray radiation. Variations of gamma spectra of the Seyfert galaxy NGC 4151 and quasar 3C 273 caused by variable X-ray radiation from these sources have been computed within the framework of this model. The results are in agreement with the available experimental data.