Simulation studies of electron acceleration to ultrarelativistic energies caused by small pulses generated in shock waves

Electron acceleration caused by small pulses in shock waves is studied with relativistic particle simulations. The simulations show that a compressive small pulse generated in a shock wave can accelerate electrons to ultrarelativistic energies. If the external magnetic field is reversed across a neutral sheet, the shock wave creates a field-reversed small pulse, in addition to compressive ones, which also accelerates electrons to ultrarelativistic energies. A theoretical analysis is made on the electron acceleration due to these two types of small pulses. It is confirmed that the simulation results are consistent with the theoretical predictions. (author)