Neutrino mass in cosmology: status and prospects

TL;DR

This work surveys how massive neutrinos influence cosmology through both the background expansion and the growth of structure, emphasizing the linear Boltzmann treatment and the nonlinear regime. It details a suite of methods—from $N$-body simulations to higher-order perturbation theory and renormalisation-group approaches—for predicting the nonlinear matter power spectrum in the presence of massive neutrinos. The paper reviews current constraints on $\sum m_\nu$ and outlines how upcoming Planck-like CMB data, galaxy surveys, weak lensing, cluster counts, and 21 cm measurements could push sensitivities toward $\sigma(\sum m_\nu)\sim 0.04$ eV. A central message is that controlling nonlinear physics and galaxy bias is essential to fully exploit future data and achieve precise neutrino mass determinations from cosmology.

Abstract

I give an overview of the effects of neutrino masses in cosmology, focussing on the role they play in the evolution of cosmological perturbations. I discuss how recent observations of the cosmic microwave background anisotropies and the large-scale matter distribution can probe neutrino masses with greater precision than current laboratory experiments. I describe several new techniques that will be used to probe cosmology in the future, as well as recent advances in the computation of the nonlinear matter power spectrum and related observables.

Figures (5)

• Figure 1: The cosmic microwave background temperature anisotropy spectrum for a model with massless neutrinos and two models with massive neutrinos. Data are from WMAP after three years of observation Hinshaw:2006ia.
• Figure 2: The large-scale matter power spectrum for a model with massless neutrinos and two models with massive neutrinos. The data points are from the 2dF survey Cole:2005sx.
• Figure 3: The large-scale matter power spectrum for massive neutrino cosmologies relative to the case with massless neutrinos from $N$-body simulations. The solid/green lines represent the predictions from linear perturbation theory, while the colourful dotted/dashed lines are the results from full-scale nonlinear simulations for different neutrino masses ($\sum m_\nu$) indicated on the plot. Figure reproduced from reference Brandbyge:2008rv.
• Figure 4: Halo mass function for cosmologies with the indicated neutrino masses ($\sum m_\nu$). The 0.0 eV case corresponds to the $\Lambda$CDM model. Figure reproduced from reference Brandbyge:2010ge.
• Figure 5: Relative differences between the total matter power spectra for a pure $\Lambda$CDM cosmology and three models with massive neutrinos, with $f_\nu=\Omega_\nu/\Omega_m=0.1$ (red/solid), 0.05 (blue/dotted), and 0.01 (green/dash) at $z=1$ (left) and $z=3$ (right). Thick lines indicate results including the one-loop correction, while the linear results are represented by the thin lines. The three vertical lines indicate the maximum $k$ values at which the linear and the one-loop corrected matter power spectra are accurate to better than 1% and 5%.