The Synchrotron Boiler: a Thermalizer in Seyfert Galaxies

Abstract

There are difficulties in understanding what keeps the plasma thermalized in compact sources, especially during rapid variations of the emitted flux. Particle-particle collisions are too inefficient in hot rarefied plasmas, and a faster process is called for. Synchrotron absorption is such a process. We show that relativistic electrons can thermalize in a few synchrotron cooling times by emitting and absorbing cyclo-synchrotron photons. The resulting equilibrium distribution is a Maxwellian at low energies, with a high energy power law tail when Compton cooling is important. Assuming that the particles emit completely self absorbed synchrotron radiation while they at the same time Compton scatter ambient UV photons, we calculate the time dependent behavior of the distribution function, and the final high energy spectra.

2 pages, 1 figure.ps. Latex (memsait.sty). To apper in the Proceedings of "Dal Micro al Mega Parsec: Secondo Congresso Nazionale sui Nuclei Galattici Attivi (From Micro to Mega Parsecs: Second Italian National Workshop on Active Galactic Nuclei)"