Positron acceleration to ultrarelativistic energies by a shock wave in a magnetized electron–positron–ion plasma

Abstract

Positron acceleration in oblique shock waves is studied with relativistic, electromagnetic, particle simulations with full particle dynamics. In the simulations, some positrons have been accelerated to energies γ∼600, where γ is the Lorentz factor. The electric field parallel to the magnetic field plays an essential role in the acceleration; it prevents some positrons from passing through the shock wave. For certain shock propagation velocities and angles, these positrons stay around the shock front for long periods of time, moving roughly parallel to the external magnetic field, and gain great energies. These properties are in good agreement with a proposed acceleration model.