Diffusive Shock Acceleration Of Relativistic Particles

In this lecture I am going to look at the mechanism of diffusive shock acceleration of energetic particles which has been proposed by Krymsky (1977), Axford, Leer and Skadron (1977) and Bell (1978) as the means by which both relativistic electrons in supernova remnants and the galactic cosmic rays are produced. Most of the work on this subject has neglected the effect that the relativistic particles have on the dynamics of the thermal gas. We shall see that current theories of the interaction between the relativistic particles and the thermal gas are not sensible once such effects are included and that we really need to look much more carefully at the fundamental physics of the problem.