Beyond Protons: Multimessenger Imprints of Heavy Nuclei in High-Energy Neutrino Sources
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Salle des Sommets
LAPTh
Joint neutrino and gamma-ray observations offer a powerful probe of the physical conditions in high-energy astrophysical sources, including their size, particle densities, and acceleration and production mechanisms. Yet the composition of the accelerated nuclei remains largely unknown. If heavy nuclei are present in compact, photon-rich regions, they can photodisintegrate, undergo Bethe-Heitler pair production and photomeson interactions, and initiate nuclear and electromagnetic cascades before escaping the source.
In this talk, I will discuss how these processes reshape the neutrino and gamma-ray output of high-energy neutrino sources. Using detailed Monte Carlo simulations, I will show how the interplay of nuclear fragmentation, Bethe-Heitler energy losses, and photomeson production modifies the multimessenger signal. I will then apply this framework to NGC 1068, one of the few extragalactic objects with evidence for high-energy neutrino emission, and discuss how MeV-GeV gamma-ray observations, including a dedicated re-analysis of archival COMPTEL data, can constrain the injected nuclear composition.