Can cosmology detect hierarchical neutrino masses?

TL;DR

The paper assesses how future CMB and LSS observations, analyzed with a Fisher matrix in a 9-parameter cosmology, can constrain the absolute neutrino mass scale. It shows Planck combined with SDSS can measure the heaviest neutrino mass at roughly $0.12$ eV (95% CL), with a future large-volume LSS survey potentially reaching $0.03$–$0.06$ eV. The study highlights degeneracies with $H_0$ and $\Omega_b$ and discusses the role of nonlinear LSS modeling and $k$-space cuts in achieving robust constraints. Overall, cosmological data could detect hierarchical neutrino masses on timescales comparable to or shorter than forthcoming direct experiments, provided nonlinearities are well controlled and survey volumes are sufficient.

Abstract

We have carefully analysed the potential of future Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) measurements to probe neutrino masses. We perform a Fisher matrix analysis on a 9-dimensional cosmological parameter space and find that data from the Planck CMB experiment combined with the Sloan Digital Sky Survey (SDSS) can measure a neutrino mass of 0.12 eV at 95% conf. This is almost at the level of the 0.06 eV mass suggested by current neutrino oscillation data. A future galaxy survey with an order of magnitude larger survey volume than the SDSS would allow for a neutrino mass determination of 0.03-0.05 eV (95% conf.).

Figures (6)

• Figure 1: The function $Q(n)$ described in Eq. (\ref{['eq:qn']}).
• Figure 2: The change in $C_l$ due to a neutrino mass of 0.07 eV. The shaded band is the cosmic variance error of $\Delta C_l/C_l = 1/\sqrt{2l+1}$.
• Figure 3: Estimated $1\sigma$ error bars on $m_\nu$ from the Fisher matrix analysis using only CMB data. The thick solid line corresponds to $m_\nu = 0.07$ eV, and the hatched region above $l_{P,{\rm max}}=1500$ is the region where the CMB signal is dominated by foregrounds. The blank triangle in the upper left corner is the region where $l_{P,{\rm max}} >l_{T,{\rm max}}$.
• Figure 4: The estimated $1\sigma$ error bar on $m_\nu$ using CMB data from MAP combined with a hypothetical LSS survey. The thick solid line corresponds to $m_\nu = 0.07$ eV.
• Figure 5: The estimated $1\sigma$ error bar on $m_\nu$ using CMB data from Planck combined with a hypothetical LSS survey. The thick solid line corresponds to $m_\nu = 0.07$ eV.