Normalized spectral distribution in dimensionless grid units of a representative macro-particle. The corresponding Lagrangian particle is located in the jet’s spine just before entering the back-flow. The initial energy bins are chosen to be within 10 ≤ γ ≤ 10⁷. The particle is injected onto the grid through the jet orifice at epoch 20 (each color represents a different simulation epoch). The radiative losses experienced by this NTP are visible as the particle’s energy distribution evolves (in time) from right to left.