High Energy Plasma Physics in Black Hole Environment with Jets.

The Compton Gamma Ray Observatory revealed the high energy emission of some Active Galactic Nuclei called "Blazars"; few of them have also been observed by ground Cererenkov arrays. Those sources observed with Whipple Observatory emit gamma rays up to few TeV. From the spectral data and variability measurements, a purely electrodynamical description of this emission can be proposed, provided that it comes from relativistic flares at the beginning of the jet. Because of the source compacity, the creation of electron-positron pairs and their escape from the black hole environment could likely explain the shape of the spectra. A plasma dominated by relativistic electrons (positrons) close to equipartition with the magnetic field is a suitable acceleration medium that can account for both the required high Lorentz factors and the short variability.