Signature neutrinos from ultrahigh-energy photons

TL;DR

This paper explores how ultrahigh-energy photons interacting with the early universe's background radiation produce neutrinos, which can serve as signatures to identify the origins of cosmic rays beyond the GZK cutoff.

Contribution

It introduces a novel mechanism for neutrino production from ultrahigh-energy photons at high redshift, providing a potential method to trace cosmic ray sources beyond the GZK limit.

Findings

Neutrinos from muon and pion decays have distinctive spectral features.

High redshift conditions enable pair production of muons and pions by ultrahigh-energy photons.

Neutrino signatures can indicate the presence of ultrahigh-energy photons in the early universe.

Abstract

At high red shift, the temperature of cosmic microwave background is sufficiently high for the ultrahigh-energy photons to pair-produce muons and pions through interactions with the background photons. At the same time, the radio background and magnetic fields are too weak to drain energy out of the electromagnetic cascade before the muons and pions are produced. Decays of the energetic muons and pions yield neutrinos with some distinctive spectral properties that can be detected and can indicate the presence of ultrahigh-energy photons at high red shift. The neutrino signature can help identify the origin of cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff.