Study and reproducibility of the SRG/eROSITA background with particle rejection on and off

For more than six years SRG/eROSITA is the first X-ray telescope in orbit around the second Lagrangian point in the Sun-Earth system. We present an updated study of its instrumental background based on cleaned data and improved simulations, carried out in the framework of the eROSITA Background Working Group. We examine the standard observing mode with minimum ionising particle rejection switched on as well as the non-standard mode with particle rejection switched off, which was set from time to time to monitor the overflow trails and patterns left by energetic particles. We show that, in the first case, Geant4 simulations allow to reproduce quite well the measured residual background; in the second case, the simulations support the analysis and interpretation of the observed trails, though a peculiar feature of a small minority of them, which apparently split from one frame into the next one, is not reflected in the simulations.