"Ab-initio studies of particle acceleration in astrophysical shocks"

Particle acceleration in astrophysical shocks is central to the production of nonthermal radiation from a large variety of astrophysical sources, ranging from supernova remnants to GRB jets. The process of acceleration is an intrinsically multi-scale problem, connecting plasma microphysics at the shock to self-generated instabilities driven by accelerated particles far from the shock. With the development of ab-initio numerical simulations, many details of the shock acceleration mechanism can now be studied directly. In this talk I will review the progress in kinetic (particle-in-cell, PIC) simulations of shock structure and particle acceleration in various regimes, and focus on processes that lead to electron acceleration in non-relativistic shocks, including field amplification, electron heating, and nonlinear regulation of shock injection. The lessons learned from microscopic PIC simulations suggest pathways to larger simulations that use augmented MHD techniques to study shock acceleration on the scales of astrophysical objects. I will discuss such MHD-PIC approaches and applications of current results to morphologies and spectra of nonthermal emission from supernova remnants and galaxy clusters.