Observable consequences of Langmuir turbulence in active galactic nuclei

The author discusses in detail the observable consequences of nonlinear microscopic plasma processes in active galactic nuclei. The combination of several elementary momentum-gain (shock acceleration and stochastic acceleration) and momentum-loss processes (synchrotron radiation, inverse Compton scattering) produces an almost monoenergetic distribution function of relativistic electrons, called the pile-up, which excites Langmuir waves. Turbulent wave-wave and wave-particle interactions lead to nonlinear stabilization of the pile-up. The temporal and spatial evolution of the Langmuir waves and the relativistic electrons determines the shape and time scale of the spectral variations. The model is applied to extragalactic nuclei and to the galactic center as well