Modeling Neutrino Emission from Supernova Remnants via Proton-Proton Collisions

Identifying the sources of high-energy astrophysical neutrinos remains a key challenge in modern multi-messenger astronomy. We estimate the neutrino flux from Galactic supernova remnants (SNRs), widely regarded as efficient accelerators of Galactic cosmic rays (CRs). CR protons accelerated at SNR-driven shocks gain energy through multiple crossings of the shock surface via wave–particle interactions, a process known as diffusive shock acceleration (DSA). These high-energy protons undergo inelastic proton-proton collisions, producing neutral and charged pions. Neutral pions decay into gamma-rays, while charged pions decay into neutrinos. SNRs may also emit gamma-rays from leptonic processes such as inverse-Compton scattering, which do not contribute to neutrino production. We treat the fraction of gamma-rays originating from hadronic processes as a free parameter and assess its impact on neutrino detectability over observational time. Using gamma-ray spectra from Fermi-LAT bright SNRs, we infer CR proton distributions and compute the corresponding neutrino fluxes. Although individual SNRs may yield fluxes below the sensitivity of current observatories (e.g., IceCube, KM3Net, Baikal-GVD), stacking multiple sources significantly improves detectability. Our analysis indicates that even with a hadronic gamma-ray fraction below 50%, neutrino signals could be observable within a 30-year observation period. These results highlight the importance of source selection and stacking strategies, providing theoretical guidance for optimizing future multi-messenger observations.