Constraints on the PeV emission zone for Point B in Figure 3, i.e., the 3σ solution that yields the global minimum decay index. The two panels show the results for δ = 2 and 3, respectively. The black curves represent the magnetic pair-production optical depth τ_γB, and the red curves represent the confinement energy E_conf. The horizontal dotted lines mark τ_γB = 1 and the most conservative threshold E_conf = 10 PeV. The shaded region shows where both conditions are satisfied simultaneously.