Comparison between observed (blue data points) and modeled (curves) differential fluxes at higher and lower energies. Modeled energetic particles are accelerated at the SIR reverse compression or shock and propagate back to PSP along sub-Parker field lines (black curves) and Parker field lines (blue curves). Observed differential fluxes (averaged over 1–5 MeV, top, and 200–500 keV, bottom) are compared with modeled fluxes (2 MeV, top, and 250 keV, bottom).