ИСТИНА

The last decade marked a great increase of the number of observed gamma-loud Active Galactic Nuclei (AGN) by ground-based gamma-ray detectors up to redshift z≈0.5. One might expect that absorption of the primary Very High Energy (VHE) photons on Extragalactic Background Light (EBL) would produce a marked cutoff in the observed spectrum, which is not observed, thus giving rise to the VHE anomaly in AGN spectra, often called the pair-production anomaly. Most of research done on the subject neglected the secondary photons emitted from the electromagnetic cascades that may contribute to the observed flux. In the present work, for the first time, a quantitative study of the cascade explanation of the VHE anomaly is performed with modern statistical methods. It is shown that cascade photons may be partly responsible for the VHE anomaly under reasonable assumptions on the primary spectrum of the source, EBL model, and extragalactic magnetic field (EGMF) model.