Fermi-LAT limits at 95% confidence level for the one-month time interval compared with the π⁰ decay differential flux from a proton population with E_cutoff = 1 PeV (solid line), 10 TeV (dashed line), or 1 TeV (dotted line). These have the same normalisation N₀, and a CR proton energy of E_CR = 2.7 × 10⁴⁶ erg, E_CR = 1.8 × 10⁴⁶ erg, and E_CR = 1.5 × 10⁴⁶ erg, respectively. Limits at energies greater than 10^1.5 GeV lie above 10⁻¹¹ erg cm⁻² s⁻¹. For the target material, a density ρ₀ = 5.6 × 10⁻¹⁴ g cm⁻³ (Bostroem et al. 2023) is assumed.