Diffusive Shock Acceleration at Oblique High Mach Number Shocks

The current paradigm of cosmic-ray (CR) origin states that the greater part of galactic CRs is produced by supernova remnants. The interaction of supernova ejecta with the interstellar medium after a supernova's explosions results in shocks responsible for CR acceleration via diffusive shock acceleration (DSA). We use particle-in-cell (PIC) simulations and a combined PIC-magnetohydrodynamic (PIC-MHD) technique to investigate whether DSA can occur in oblique high Mach number shocks. Using the PIC method, we follow the formation of the shock and determine the fraction of the particles that gets involved in DSA. With this result, we use PIC-MHD simulations to model the large-scale structure of the plasma and the magnetic field surrounding the shock and find out whether or not the reflected particles can generate upstream turbulence and trigger DSA. We find that the feasibility of this process in oblique shocks depends strongly on the Alfvenic Mach number, and the DSA process is more likely to be triggered at high Mach number shocks.

Automated summary

This article investigates the occurrence of diffusive shock acceleration (DSA) in oblique high Mach number shocks. Using particle-in-cell (PIC) simulations and a combined PIC-magnetohydrodynamic (PIC-MHD) technique, the study examines the formation of the shock and determines the fraction of particles involved in DSA. The researchers also use PIC-MHD simulations to model the plasma and magnetic field surrounding the shock and determine whether reflected particles can generate upstream turbulence and trigger DSA. The results show that the feasibility of this process in oblique shocks depends strongly on the Alfvenic Mach number, with high Mach number shocks being more likely to trigger DSA.