The Effect of Thermal Neutrino Motion on the Non-linear Cosmological Matter Power Spectrum

TL;DR

This paper investigates how thermal neutrino velocities influence the non-linear matter power spectrum in cosmology, providing new analytic and simulation methods to accurately incorporate neutrino effects for future high-precision surveys.

Contribution

It introduces the first consistent inclusion of neutrino thermal velocities in non-linear structure formation models, along with an analytic expression and a fast simulation method.

Findings

Neutrino thermal velocities significantly affect the matter power spectrum.

The proposed methods achieve 1% accuracy for neutrino masses below 0.15 eV.

Effects are detectable in upcoming high-precision cosmological surveys.

Abstract

We have performed detailed studies of non-linear structure formation in cosmological models with light neutrinos. For the first time the effect of neutrino thermal velocities has been included in a consistent way, and the effect on the matter power spectrum is found to be significant. The effect is large enough to be measured in future, high precision surveys. Additionally, we provide a simple but accurate analytic expression for the suppression of fluctuation power due to massive neutrinos. Finally, we describe a simple and fast method for including the effect of massive neutrinos in large-scale N-body simulations which is accurate at the 1% level for \sum m_nu < 0.15 eV.