Energetic electrons downstream of Earth's bow shock: Simulations of acceleration by shock structure

Energetic electrons have been widely observed downstream of the Earth's bow shock, although the exact electron acceleration mechanism is not completely understood. Using a combination of hybrid shock simulation and electron test particles, we show how trapping by two dimensional structure in the form of ripples can cause electrons to be convected downstream with the magnetic field, despite having magnetic moments which suggest that they should be reflected upstream. These electrons undergo considerable Fermi acceleration during this shock transition and may explain the observed energetic downstream populations.