Observations in the heliosphere show that magnetized collisionless shocks are very efficient at ion heating. Ion heating is a nonadiabatic process and the temperature downstream of the shock is not proportional to the upstream temperature. Directly transmitted ions may be responsible for most of the downstream temperature. We determine the gyrophase-dependent distribution of directly transmitted ions just behind the magnetic jump, the gyrotropic distribution farther behind the shock, and establish the relation with the magnetic compression and the maximum overshoot magnetic field. These relations may be used as proxies for estimating the shock Mach number when reliable measurements of density are not available.
Michael Gedalin (2021), Shock Heating of Directly Transmitted Ions, The Astrophysical Journal, 912(2), doi: 10.3847/1538-4357/abf1e2