Minimum-χ² map in the (B, H) plane. The dashed contours mark the 1σ, 2σ, and 3σ confidence regions defined by the corresponding Δχ² thresholds for two parameters of interest. The white dot-dashed, dashed, and dotted lines show constant (BH) values of (10^{13}), (10^{14}), and (10^{15}\ {\rm G,cm}), respectively. Point A denotes the largest-BH solution formally enclosed by the 3σ contour, while Point B marks the 3σ solution that yields the global minimum decay index required to satisfy both τ_γB < 1 and robust threshold E_conf ≥ 10 PeV.