Diffuse Boosted Cosmic Neutrino Background

TL;DR

This paper calculates the flux of high-energy cosmic relic neutrinos boosted by cosmic rays, analyzes their detectability, and constrains the cosmic neutrino background density based on current experimental non-observations.

Contribution

It provides the first detailed calculation of the diffuse boosted relic neutrino flux considering different cosmic-ray models and discusses implications for future neutrino detection.

Findings

Current experiments exclude neutrino overdensities > 10^4

The diffuse flux depends on cosmic-ray spectral slope and evolution

Future detectors may observe boosted relic neutrinos if overdensities are high

Abstract

Energetic cosmic rays scatter off the cosmic neutrino background throughout the history of the Universe, yielding a diffuse flux of cosmic relic neutrinos boosted to high energies. We calculate this flux under different assumptions of the cosmic-ray flux spectral slope and redshift evolution. The non-observation of the diffuse flux of boosted relic neutrinos with current high-energy neutrino experiments already excludes an average cosmic neutrino background overdensity larger than $\sim 10^{4}$ over cosmological distances. We discuss the future detectability of the diffuse flux of boosted relic neutrinos in light of neutrino overdensity estimates and cosmogenic neutrino backgrounds.