Authors: Immanuel Christopher Jebaraj (Department of Physics and Astronomy, University of Turku, Finland), Michael Gedalin (Ben Gurion University of the Ne'gev, Israel), Mikhail Malkov (University of California, San Diego, USA), Vladimir Krasnoselskikh (LPC2E, Orleans, France), Oleksiy Agapitov (Space Sciences Laboratory, University of California, Berkeley, USA)

Collisionless shocks are among the most efficient particle accelerators, yet how their multiscale structure evolves and produces the energetic particles they release is still not understood. In the inner heliosphere, Parker Solar Probe and Solar Orbiter now resolve shocks when they are at their strongest, while near-Earth spacecraft sample them after the long outward propagation. We now see that this structure is also multidimensional, and that the two must be treated together, as part of a single self-regulating system. More recently, this view has been extended to the foreshock, filled with supra- and non-thermal particles and the waves they drive. The evolution of this coupled system governs where and how efficiently electrons and ions are injected and accelerated.

I want to approach this through the way a shock redistributes the energy it processes. That energy goes into heating, magnetic compression, turbulence, accelerated particles, and radiation. The particles we study are only one of them. The partition depends on the Mach number, the shock-normal angle, and the plasma beta. What matters, then, is less the individual shock than the conditions it works under. Our models cannot yet reproduce that partition and requires a different philosophical approach to modelling shocks in general.