Relic neutrinos: local clustering and consequences for direct detection

TL;DR

This paper reviews the potential local clustering of relic neutrinos due to gravitational attraction and discusses implications for their direct detection, emphasizing the importance of local overdensity for experimental prospects.

Contribution

It provides an overview of neutrino clustering effects and assesses their impact on the expected event rates in future direct detection experiments.

Findings

Massive neutrinos can cluster in the galaxy, increasing local density.

Local overdensity of relic neutrinos affects detection prospects.

Current understanding of neutrino clustering informs experimental strategies.

Abstract

The Cosmic Neutrino Background is a prediction of the standard cosmological model, but it has been never observed directly. Experiments with the aim of detecting relic CNB neutrinos are under development. For such experiments, the expected event rate depends on the local number density of relic neutrinos. Since massive neutrinos can be attracted by the gravitational potential of our galaxy and cluster locally, a local overdensity of relic neutrinos should exist at Earth. We report the status of our knowledge on the clustering of neutrinos and the consequences for future direct detection experiments.