The synchrotron and inverse Compton losses usually experienced by relativistic electrons within the environment of an active galactic nucleus constrains models which are based on the direct transport of relativistic electrons out of the central engine. Moreover, even if relativistic electrons are produced just beyond the accretion disk of the active galaxy, the large distance from the core to where the jet becomes bright (tens of kpc) is much greater than that which the electrons could travel during their synchrotron lifetimes. Therefore, a reacceleration mechanism which acts on the electrons at the sites where their interactions with ambient magnetic fields give rise to the radio jets observed in extragalactic radio sources is required. Significant numbers of relativistic neutrons may be produced in the central engine of active galactic nuclei. If the relativistic neutrons streaming out of the central engines of active galactic nuclei are able to travel beyond the accretion disk, then the by-products of the relativistic neutron decay will produce radiative signatures well outside the central region of activity. Coulomb scattering of nonrelativistic electrons off relativistic protons can boost these electrons to relativistic speeds, and can contribute a significant portion of the synchrotron emission observed in radio sources.
The Astrophysical Journal 01/1994; 422(2):537-541. DOI:10.1086/173747