Two scenarios of diffusion and acceleration. Upper panel: Diffusive shock acceleration with a diffusion coefficient D′_E ∼ E^{′ − 1}. Lower panel: Stochastic acceleration with D′_E ∼ E^′0.3. The timescales are given for the wide range of parameters η, B′, and R′_j expected at distances 10¹⁷ cm ≲ r ≲ pc, as detailed in the main text. Black crosses show the maximum energy of electrons and protons predicted by the respective scenario. Green bands show the allowed range of E′_e and E′_p necessary to describe the multimessenger data.