Observing EeV neutrinos through the Earth: GZK and the anomalous ANITA events

TL;DR

This paper updates the calculation of tau neutrino regeneration and explores its implications for anomalous ANITA events and cosmogenic neutrino flux detection, finding that the ANITA events are unlikely caused by localized tau neutrino sources.

Contribution

It provides a new calculation of tau neutrino regeneration and applies it to analyze the ANITA events and cosmogenic neutrino detection prospects.

Findings

ANITA events unlikely caused by localized tau neutrino sources

Regenerated neutrino flux constraints from IceCube data

Potential for detecting cosmogenic neutrinos with future detectors

Abstract

Tau neutrinos are unique cosmic messengers, especially at extreme energies. When they undergo a charged-current interaction, the short lifetime of the produced tau gives rise to secondary tau neutrinos that carry a significant fraction of the primary neutrino energy. This effect, known as tau neutrino regeneration, has not been applied to its full potential in current generation neutrino experiments. In this work, we present an updated calculation of tau neutrino regeneration, and explore its implications for two scenarios: the recent anomalous ANITA events and the cosmogenic neutrino flux. For the former, we investigate the idea of localized emission and find that the maximum secondary neutrino flux allowed by IceCube measurements implies a primary flux that is incompatible with the ANITA observation, regardless of the assumed source energy spectrum. For the latter, we study the prospect of detecting the cosmogenic neutrino flux of regenerated PeV neutrinos with current and next generation neutrino detectors.