Data from the main simulation (Sect. 3.1), with a background magnetization respectively for ions and electrons . Top: snapshots of a random selection of electrons in the whole simulation domain. Red particles are inside the current sheet at t = 0, green ones are outside. Bottom: Lorentz factor distributions. Red (green) curves concern the red (green) population. For the green curves, times are ordered as dark to light green, with values 0, 750, 1500, 2250, 3000, 3750, i.e., one curve every . The blue dashed line indicates the final power-law slope of the background accelerated particles.