The hadronic model of Active Galactic Nuclei

We review the hadronic model for Active Galactic Nuclei (AGN). This model, which can be applied to all AGN, advocates the acceleration of protons to ultrarelativistic energies by shock fronts which are formed a few Schwarzschild radii away from the central black hole. The necessary consequences of this hypothesis are discussed. These include the formation of electromagnetic cascades which are initiated by the injection of secondary electrons and photons inside the source, as well as the production and escape of neutrons and neutrinos. As a result of the neutron escape we emphasize that AGN can be sources of TeV radiation.