Left: evolution of particle energy as a function of the distance l along the streamline (in units of the orbital separation). Right: evolution of the particle energy distribution along the streamline (lighter colours for later times i.e. increasing distance l). The top panels correspond to the streamline starting at o = 48° and the bottom panels to the streamline starting at o = 115° (both are identified by an initial dot in Fig. 2). The distribution in the bottom right panel “jumps” when the particles cross the reflected shock and are re-energised. The evolution is calculated at periastron for our reference simulation.