Comparison of Particle Acceleration at Planetary Bow Shocks and Interplanetary Shocks

The spatial size of collisionless shock waves is suggested to play an important role in determining the maximum energy gain of particles accelerated at heliospheric and astrophysical shocks. In addition, shocks energize particles with different starting/upstream energies differently. This study aims to investigate the maximum energy gain at heliospheric shocks at various sizes and seed conditions. In our comparison, we focus on the Martian, Venusian, terrestrial, and Jovian bow shocks, as well as interplanetary shocks, using spacecraft data from the MAVEN, Venus Express, Magnetospheric Multi-Scale (MMS), Juno, Parker Solar Probe, and Solar Orbiter spacecraft missions, respectively. These shock systems are chosen because of their vast physical size difference and therefore constitute perfect laboratories for the intended comparison study. We explore the maximum energy dependence on the shock obliquity and shock Mach number measured for each shock crossing. In addition to the maximum energy, we also compare the suprathermal electron spectral index for the different sets of shocks and its dependence on the shock obliquity.