A photon breeding mechanism for the high-energy emission of relativistic jets

We propose a straightforward and efficient mechanism for the high-energy emission of relativistic astrophysical jets associated with an exchange of interacting high-energy photons between the jet and the external environment. Physical processes playing the main role in this mechanism are electron–positron pair production by photons and the inverse-Compton scattering. This scenario has been studied analytically as well as with numerical simulations demonstrating that a relativistic jet (with the Lorentz factor larger than 3–4) moving through the sufficiently dense, soft radiation field inevitably undergoes transformation into a luminous state. The process has a supercritical character: the high-energy photons breed exponentially being fed directly by the bulk kinetic energy of the jet. Eventually particles feedback on the fluid dynamics and the jet partially decelerates. As a result, a significant fraction (at least 20 per cent) of the jet kinetic energy is converted into radiation mainly in the MeV–GeV energy range. The mechanism maybe responsible for the bulk of the emission of relativistic jets in active galactic nuclei, microquasars and gamma-ray bursts.