Speaker
Description
High-energy neutrinos are often regarded as a robust signature of hadronic activity in astrophysical sources. However, at sufficiently high energies, purely leptonic electromagnetic (EM) cascades initiated by photons or $e^\pm$ can convert a non-negligible fraction of injected EM power into neutrinos through muon/pion-producing QED processes. In this talk I will present a unified and quantitative treatment of this “leptonic neutrino” channel in two complementary settings: (i) ultra-high-energy photon injection in the high-redshift Universe, where interactions with the CMB dominate, and (ii) EM cascades developing inside astrophysical sources with dense target photon fields.
We quantify the relative importance of the relevant $\gamma\gamma$ and $e\gamma$ interaction channels at ultra-high energies, and show how their competition governs cascade development and imprints characteristic features on the resulting leptonic neutrino spectrum.
I will introduce MUNHECA, a public Monte Carlo python3 code that models the full cascade microphysics across configurable target photon backgrounds and interaction channels, enabling reproducible predictions for the emergent neutrino spectra in cosmological and source environments.
While focused on neutrino phenomenology, the same cascade physics is applicable to both conventional astrophysical emitters and exotic ultra-high-energy injection scenarios, linking neutrino astronomy to broader ICHEP topics in astroparticles.
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