Electron acceleration to ultrarelativistic energies in a collisionless oblique shock wave

Electron motion in an oblique shock wave is studied by means of a one-dimensional, relativistic, electromagnetic, particle simulation code with full ion and electron dynamics. It is found that an oblique shock can produce electrons with ultra-relativistic energies; Lorentz factors with $\gamma \gto 100$ have been observed in our simulations. The physical mechanisms for the reflection and acceleration are discussed, and the maximum energy is estimated. If the electron reflection occurs near the end of a large-amplitude pulse, those particles will then be trapped in the pulse and gain a great deal of energy. The theory predicts that the electron energies can become especially high at certain propagation angles. This is verified by the simulations.