Effects of the neutrino mass splitting on the non-linear matter power spectrum

TL;DR

This study uses cosmological N-body simulations to explore how different neutrino mass hierarchies influence the non-linear matter power spectrum, revealing small but potentially measurable effects that could inform neutrino physics.

Contribution

The paper introduces detailed N-body simulations including individual neutrino masses to analyze hierarchy effects on the matter power spectrum beyond linear theory.

Findings

Non-linearities amplify hierarchy effects at mildly non-linear scales.

The difference between hierarchies is about 0.5% for 0.1 eV neutrino mass sum.

Potential to measure hierarchy effects with upcoming surveys.

Abstract

We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to the linear theory predictions, we find that non-linearities enhance the effect of hierarchy on the matter power spectrum at mildly non-linear scales. The difference between the different hierarchies is about 0.5% for a sum of neutrino masses of 0.1eV. Albeit this is a small effect, it is potentially measurable from upcoming surveys. In combination with neutrinoless double-beta decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.