Minimal Cosmogenic Neutrinos

TL;DR

This paper establishes a model-independent lower limit on the flux of cosmogenic neutrinos based on observed ultra-high energy cosmic rays, reducing uncertainties related to source environment assumptions.

Contribution

It introduces a method to derive a lower bound on cosmogenic neutrino flux using observable cosmic ray data, independent of source environment uncertainties.

Findings

Derived explicit lower limits for neutrino flux under conservative source evolution assumptions.

Linked neutrino flux bounds directly to observable cosmic ray spectrum and composition.

Reduced model dependence in predicting cosmogenic neutrino flux.

Abstract

The observed flux of ultra-high energy (UHE) cosmic rays (CRs) guarantees the presence of high-energy cosmogenic neutrinos that are produced via photo-hadronic interactions of CRs propagating through intergalactic space. This flux of neutrinos doesn't share the many uncertainties associated with the environment of the yet unknown CR sources. Cosmogenic neutrinos have nevertheless a strong model dependence associated with the chemical composition, source distribution or evolution and maximal injection energy of UHE CRs. We discuss a lower limit on the cosmogenic neutrino spectrum which depends on the observed UHE CR spectrum and composition and relates directly to experimentally observable and model-independent quantities. We show explicit limits for conservative assumptions about the source evolution.