Simulation study of particle reflection and injection in magnetized collisionless shocks

Collisionless shocks are common in astrophysical plasmas and are known to be important in the acceleration of both high-energy electrons and protons. While diffusive shock acceleration is well established, particle injection into the nonthermal tail remains an important puzzle, particularly for electrons. In this work we present the results of one- and two-dimensional particle-in-cell simulations of magnetized collisionless shocks to study how the properties of the shock reflected and injected particles depend on the plasma parameters, namely the Alfvénic and sonic Mach numbers and the orientation of the ambient magnetic field with respect to the shock normal.