Interplay between collisionless and collisional heating in high-Mach number shocks*

Shock waves produced by violent interactions of supersonic plasma flows with the interstellar medium or planetary magnetospheres are observed to heat the plasma, amplify magnetic fields, and accelerate electrons and protons to relativistic speeds. However, the exact mechanisms that control energy partition in these shocks remain a mystery. This is particularly challenging for high Mach number shocks, such as those associated with supernova remnants, where spacecraft data in the relevant regime is scarce and the shock structure cannot be directly resolved from observations. I will discuss recent progress in using the combination of fully kinetic simulations and laser-driven laboratory experiments at the National Ignition Facility to study energy partition in high-Mach number collisionless shocks. In particular, I will focus on the shock microphysics and how the interplay between collisionless and collisional processes impacts electron and ion heating.