Paper detail

A new interpretation of the gamma-ray observations of active galactic nuclei

Gamma-ray telescopes have reported some surprising observations of multi-TeV photons from distant active galactic nuclei (AGN), which show no significant attenuation due to pair production on either the extragalactic background light (EBL), or the photons near the source. We suggest a new interpretation of these observations, which is consistent with both the EBL calculations and the AGN models. Cosmic rays with energies below 50 EeV, produced by AGN, can cross cosmological distances, interact with EBL relatively close to Earth, and generate the secondary photons observed by gamma-ray telescopes. We calculate the spectrum of the secondary photons and find that it agrees with the gamma-ray data. The delays in the proton arrival times can explain the orphan flares, the lack of time correlations, and the mismatch of the variability time scales inferred from the multiwavelength observations. The gamma-ray data are consistent with the detection of the secondary photons, which has important ramifications for gamma-ray astronomy, cosmic ray physics, EBL, and the intergalactic magnetic fields (IGMF).