Gamma-ray and neutrino flares produced by protons accelerated on an accretion disk surface in AGN

Abstract

We discuss the consequences of almost rectilinear acceleration of protons to extremely high energies in a reconnection region on the surface of an accretion disk which surrounds a central black hole in an active galaxy. The protons produce $γ$-rays and neutrinos in interactions with the disk radiation as considered in several previous papers. However, in this model the secondary $γ$-rays can initiate cascades in the magnetic and radiation fields above the disk. We compute the spectra of $γ$-rays and neutrinos emerging from regions close to the disk surface. Depending on the parameters of the reconnection regions, this model predicts the appearance of $γ$-ray and neutrino flares if protons takes most of the energy from the reconnection region. In contrast, if leptons take most of the energy, they produce pure $γ$-ray flares. The $γ$-ray spectrum expected in the case of hadronic cascading is compared with the spectrum observed during the flare in June 1991 from 3C 279. The neutrino flares which should accompany these gamma-ray flares may be detected by future large scale neutrino telescopes sensitive at $\sim 10^{5}$ TeV.