Comparison of γ-ray fluxes resulting from de-excitation of nuclei (dotted lines) and π⁰-decay process (dashed lines) integrated within 25 pc from the hypothetical CR source. Left panel: we assume a proton spectrum F_p (E) ∝ E⁻² with various diffusion coefficient parameters, in which χ = 1.0 (black), 0.1 (blue), or 0.01 (red). Right panel: we assume χ = 1.0 and proton spectra F_p(E) ∝ E⁻²exp(−E∕E_cut) with various cutoff energies, in which E_cut = 1 GeV (black), 300 MeV (blue), or 100 MeV (red). Meanwhile, Q∕d² = 10³⁸erg s⁻¹ kpc⁻² and n = 1 cm⁻³ are assumedin both panels.