| Popis: |
The question of how cosmic rays are accelerated to high energies in galaxy clusters remains unresolved. Radio relics, formed by relativistic electrons produced at merger shocks, emit synchrotron radiation and are believed to be a potential source of high-energy cosmic rays, gamma-rays, and neutrinos. Recent studies have focused on electron acceleration at low Mach number merger shocks propagating in hot intracluster mediums. Using multi-scale turbulence in the shock, including ion-scale shock surface rippling, our recent PIC simulation results demonstrate that stochastic shock-drift acceleration can provide electron acceleration in these conditions. A newly developed generalized fluid-particle hybrid numerical code can handle fluid electrons, ions, and an arbitrary number of kinetic species, including energetic particles. Our findings include discussions on the structure of quasi-perpendicular shocks obtained from standard hybrid simulation models, large-scale 2D and 3D simulations for varying parameters, such as plasma beta, magnetic field obliquity angle, and shock Mach number, under subcritical and supercritical conditions. Furthermore, we present our first preliminary results on electron acceleration in turbulent shocks by tracking the trajectories of an additional energetic electron population self-consistently implemented into our hybrid simulation model. |
