Authors: Jack M. Schroeder (University of Wisconsin-Madison), Jan Egedal (University of Wisconsin-Madison)

Observations show particles are efficiently heated at astrophysical shocks. However, the relative contribution from non-adiabatic processes that support electron injection to moderately relativistic energies and their precise mechanisms remain open questions. Using data from the Magnetospheric Multiscale Mission (MMS) at the Earth’s bow shock, we model two adiabatic mechanisms, direct acceleration by electric fields and adiabatic compression. In addition, we apply a model for magnetic pumping, a non-adiabatic heating mechanism that efficiently energizes trapped particles. Using a Bayesian statistical approach we seek the optimal combination of these three processes to best match the observed phase space enhancement across the shock layer. We find this framework shows several different scenarios of electron energization, some of which provide evidence that magnetic pumping could be an efficient source of electron injection at collisionless shocks.