Effects of Massive Neutrinos on the Large-Scale Structure of the Universe

TL;DR

Massive neutrinos significantly influence the large-scale structure of the universe, affecting galaxy formation, halo properties, and cosmological measurements, which can be used to constrain neutrino mass in future surveys.

Contribution

This study uses large hydrodynamic simulations to quantify the non-linear effects of massive neutrinos on dark matter haloes and cosmological observables, highlighting implications for neutrino mass constraints.

Findings

Neutrinos alter the halo mass function and two-point correlation function.

Neglecting neutrino effects can mimic signals of modified gravity.

Future galaxy surveys can constrain neutrino mass > 0.6 eV using beta measurements.

Abstract

Cosmological neutrinos strongly affect the evolution of the largest structures in the Universe, i.e. galaxies and galaxy clusters. We use large box-size full hydrodynamic simulations to investigate the non-linear effects that massive neutrinos have on the spatial properties of cold dark matter (CDM) haloes. We quantify the difference with respect to the concordance LambdaCDM model of the halo mass function and of the halo two-point correlation function. We model the redshift-space distortions and compute the errors on the linear distortion parameter beta introduced if cosmological neutrinos are assumed to be massless. We find that, if not taken correctly into account and depending on the total neutrino mass, these effects could lead to a potentially fake signature of modified gravity. Future nearly all-sky spectroscopic galaxy surveys will be able to constrain the neutrino mass if it is larger than 0.6 eV, using beta measurements alone and independently of the value of the matter power spectrum normalisation. In combination with other cosmological probes, this will strengthen neutrino mass constraints and help breaking parameter degeneracies.