Probing neutrino production in high-energy astrophysical neutrino sources with the Glashow Resonance

TL;DR

This paper explores how the Glashow resonance can differentiate between $pp$ and $p\gamma$ neutrino production mechanisms in astrophysical sources, using current and future neutrino telescope data to improve understanding of neutrino origins.

Contribution

It demonstrates the potential of Glashow resonance events to distinguish neutrino production processes with current and upcoming detectors, enhancing source characterization.

Findings

$pp$ and $p\gamma$ processes can be distinguished at 2σ significance within decades.

Glashow resonance provides a viable method to measure the $ar{ u}_e$ flux fraction.

Future experiments can probe mixed production mechanisms with improved sensitivity.

Abstract

The flavor composition of high-energy neutrinos carries important information about their birth. However, the two most common production scenarios, $pp$ (hadronuclear) and $p\gamma$ (photohadronic) processes, lead to the same flavor ratios when neutrinos and antineutrinos cannot be distinguished. The Glashow resonant interaction $\bar{\nu}_e+e^- \rightarrow W^-$ becomes a window to differentiate the antineutrino contribution from the total diffuse neutrino flux, thus lifting this degeneracy. We examine the power of Glashow resonant events in measuring the fraction of the $\bar{\nu}_e$ flux with current IceCube data, and produce projected sensitivities based on the combined exposure of planned Cherenkov neutrino telescopes around the globe. We find that $pp$ and $p\gamma$ can be distinguished at a 2$\sigma$ significance level in the next decades, in both an event-wise analysis and a more conservative statistical analysis, even with pessimistic assumptions on the spectral index of the astrophysical flux. Finally, we consider the sensitivity of future experiments to mixed production mechanisms.