  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.
