Relativistic kinetic reconnection as the possible source mechanism for high variability and flat spectra in extragalactic radio sources

We present the first synchrotron power spectra of a self-consistent kinetic reconnection scenario in the highly relativistic regime of a pair plasma. A fully electromagnetic relativistic particle-in-cell code is used to study the late-time evolution of kinetic magnetic reconnection at high resolution with a total ensemble of more than 10(8) particles. We show (1) the importance of the extremely dynamic late-time evolution of the reconnection region for the generation of nonthermal particles, (2) the efficient synchrotron emission by the accelerated fraction of particles, and (3) the application of the simulation results to pair-dominated active galactic nucleus core regions the presumable origin of "light" jets. We conclude that collisionless kinetic reconnection in the relativistic regime is capable of explaining the enormous power output of P similar to 10(47) ergs s(-1) in certain luminous intraday variable quasars and the extremely hard observed radio spectra of flat-spectrum radio quasars.