Ultrahigh-energy cosmogenic neutrino emissions in the high-redshift universe

TL;DR

This paper predicts a 50-PeV neutrino flux from high-redshift AGN emitting ultrahigh-energy protons, aligning with IceCube data and offering insights into early universe cosmic-ray activity.

Contribution

It demonstrates that high-redshift AGN can produce a neutrino flux with a 50-PeV bump consistent with observations, without fine-tuning parameters.

Findings

Neutrino flux shows a bump at around 50 PeV.

Flux aligns with current IceCube estimates.

Predicted neutrino intensity arises naturally from observed AGN properties.

Abstract

The James Webb Space Telescope (JWST) revealed a large population of active galactic nuclei (AGN) with redshifts greater than five. We show that if they emit ultrahigh-energy protons with energies up to $\lesssim 10^{19}$ eV, the cosmogenic neutrino production in the high-redshift CMB field yields a neutrino flux with a bump at around 50~PeV. This flux is consistent with the current estimate of neutrino intensity from the IceCube Neutrino Observatory. We argue that the predicted neutrino intensity naturally arises from the average AGN luminosity and number density observed by JWST, without the need for fine-tuning of relevant parameters. Future neutrino observations that confirm the 50-PeV bump and constrain the small-scale anisotropy will infer ultra-high energy cosmic-ray emissions in the early universe.