Particle Acceleration and gamma-ray emission due to magnetic reconnection around the core region of radio galaxies

Abstract: The current detectors of gamma-ray emission specially at TeV energies have too poor resolution to determine whether this emission is produced in the jet or in the core, particularly of low luminous, non-blazar AGNs (like radio galaxies). In recent works it has been found that the power released by events of turbulent fast magnetic reconnection in the core region of these sources is more than sufficient to reproduce the observed gamma-ray luminosities. Besides, 3D MHD simulations with test particles have demonstrated that a first-order Fermi process within reconnection sites with embedded turbulence results very efficient particle acceleration rates. We computed here the spectral energy distribution (SED) from radio to gamma-rays of the radio galaxies for which energy emission up to TeVs has been detected (namely, M87, Cen A, Per A, and IC 310). For this aim, we employed the acceleration model above and considered all the relevant leptonic and hadronic loss processes around the core region of the sources. We found that the calculated SEDs match very well specially with the VHE observations, therefore strengthening the conclusions above in favour of a core emission origin for the VHE emission of these sources. The model also naturally explains the observed very fast variability of the VHE emission.