Speaker
Description
Shock acceleration is generally a highly coupled problem involving nonlinear interactions between thermal plasma, waves, and nonthermal particles called cosmic rays (CRs). Upstream of the shock, the super-Alfvénic drift of CR protons excites the nonresonant streaming (Bell) instability. These unstable modes can grow to nonlinear levels, generating strong turbulence that further impacts electron dynamics. Although particle-in-cell (PIC) simulations provide a first-principle approach to shock acceleration physics, they do not always reproduce efficient electron energization. These simulations are limited to phenomena at electron kinetic scales, which makes investigating the impact of CR proton-driven turbulence on electron acceleration challenging. Using a recently developed simulation framework, we inject such turbulence upstream of non-relativistic high-Mach-number shocks. Our simulations reveal shock front corrugations that significantly influence the overall electron behavior. We observe a pronounced power law in the downstream electron energy spectrum and the onset of diffusive shock acceleration, both of which are absent in simulations with an initially homogeneous upstream medium.