Pair Creation at Shocks: Application to Agns
  We investigate the effect of pair creation on a shock structure. Actually, particles accelerated by a shock can be sufficiently energetic to boost, via Inverse Compton process for example, surrounding soft photons above the rest mass electron energy and thus to trigger the pair creation process. The increase of the associated pair pressure is thus able to disrupt the plasma flow and possibly, for too high pressure, to smooth it completely. Reversely, significant changes of the flow velocity profile may modify the distribution function of the accelerated particles in such a way that the number of particles enable to trigger the pair creation process may change, modifying consequently the pair creation rate. We propose here, using simplifying assumptions, to study the global behavior of a shock structure in an environment dominated by pairs. 
P.O. Petrucci (1), G. Henri (2), G. Pelletier (2) ((1) Oab, Milano,   Italy, (2) Laog, Grenoble, France)