Neutrino constraints from future nearly all-sky spectroscopic galaxy surveys

TL;DR

Future all-sky spectroscopic galaxy surveys combined with CMB data could detect and measure the absolute neutrino mass scale and number of neutrino species, confirming the cosmic neutrino background.

Contribution

This study evaluates the potential of upcoming galaxy surveys to detect cosmic neutrino signatures and measure neutrino properties using novel spectroscopic strategies.

Findings

Surveys can detect neutrino mass above 0.1 eV with >3-sigma confidence.

Combining surveys with Planck improves neutrino mass constraints.

Surveys can span the entire neutrino mass range allowed by oscillation experiments.

Abstract

We examine whether future, nearly all-sky galaxy redshift surveys, in combination with CMB priors, will be able to detect the signature of the cosmic neutrino background and determine the absolute neutrino mass scale. We also consider what constraints can be imposed on the effective number of neutrino species. In particular we consider two spectroscopic strategies in the near-IR, the so-called "slitless" and "multi-slit" approaches, whose examples are given by future space-based galaxy surveys, as EUCLID for the slitless case, or SPACE, JEDI, and possibly WFIRST in the future, for the multi-slit case. We find that, in combination with Planck, these galaxy probes will be able to detect at better than 3--sigma level and measure the mass of cosmic neutrinos: a) in a cosmology-independent way, if the sum of neutrino masses is above 0.1 eV; b) assuming spatial flatness and that dark energy is a cosmological constant, otherwise. We find that the sensitivity of such surveys is well suited to span the entire range of neutrino masses allowed by neutrino oscillation experiments, and to yield a clear detection of non-zero neutrino mass. The detection of the cosmic relic neutrino background with cosmological experiments will be a spectacular confirmation of our model for the early Universe and a window into one of the oldest relic components of our Universe.