Kinetic Particle-In Simulations of Asymmetric Quasi-Parallel Mildly Relativistic Plasma Collisions: Field and Electron Dynamics

A gamma-ray burst (GRB) is triggered by a stellar implosion and the subsequent ejection of an ultrarelativistic jet. The prompt emissions are attributed to mildly relativistic collisions of plasma clouds within this jet. The resulting internal shocks are instrumental in the generation of the magnetic fields and the energetic electrons, which excite the observed electromagnetic emissions. We use particle-in-cell (PIC) simulations to examine such a shock. The colliding hot magnetized plasma clouds have densities that differ by a factor of 10. Current channels form rapidly in the 3D simulation, which resemble those in a Hammer–Rostoker equilibrium, are observed also in the 2D simulation. The 2D simulation also shows the formation of a shock, which is mediated by a strong electromagnetic wave, and the energy equipartition between electrons and ions.