On the conversion of blast wave energy into radiation in active galactic nuclei and gamma-ray bursts

It has been suggested that relativistic blast waves may power the jets of A GN and gamma-ray bursts (GRB). We address the important issue how the kinet ic energy of collimated blast waves is converted into radiation. It is show n that swept-up ambient matter is quickly isotropised in the blast wave fra me by a relativistic two-stream instability, which provides relativistic pa rticles in the jet without invoking any acceleration process. The fate of t he blast wave and the spectral evolution of the emission of the energetic p articles is therefore solely determined by the initial conditions. We compa re our model with existing multiwavelength data of AGN and find remarkable agreement.