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Neutrino mass from future high redshift galaxy surveys: sensitivity and detection threshold

Steen Hannestad, Yvonne Y. Y. Wong

TL;DR

The paper addresses how future CMB and high-redshift galaxy surveys can constrain the absolute neutrino mass scale. It employs a simulation-based MCMC forecast within eight- and ten-parameter cosmologies to assess sensitivity and detection thresholds, explicitly accounting for non-Gaussian posteriors and bias marginalisation. The main finding is that, in minimal models, combining Planck with high-redshift data can reach a 95% CL sensitivity near $0.08$ eV and potentially detect neutrino masses down to about $0.05$–$0.09$ eV, whereas extended models suffer larger degeneracies raising the threshold to $\sim$0.16–0.19 eV. The study highlights the importance of including redshift evolution, BAO information, and rigorous MCMC analysis, and situates these cosmological constraints in the context of laboratory experiments like KATRIN and other future probes.

Abstract

We calculate the sensitivity of future cosmic microwave background probes and large scale structure measurements from galaxy redshift surveys to the neutrino mass. We find that, for minimal models with few parameters, a measurement of the matter power spectrum over a large range of redshifts has more constraining power than a single measurement at low redshifts. However, this improvement in sensitivity does not extend to larger models. We also quantify how the non-Gaussian nature of the posterior distribution function with respect to the individual cosmological parameter influences such quantities as the sensitivity and the detection threshold. For realistic assumptions about future large scale structure data, the minimum detectable neutrino mass at 95 % C.L. is about 0.05 eV in the context of a minimal 8-parameter cosmological model. In a more general model framework, however, the detection threshold can increase by as much as a factor of three.

Neutrino mass from future high redshift galaxy surveys: sensitivity and detection threshold

TL;DR

The paper addresses how future CMB and high-redshift galaxy surveys can constrain the absolute neutrino mass scale. It employs a simulation-based MCMC forecast within eight- and ten-parameter cosmologies to assess sensitivity and detection thresholds, explicitly accounting for non-Gaussian posteriors and bias marginalisation. The main finding is that, in minimal models, combining Planck with high-redshift data can reach a 95% CL sensitivity near eV and potentially detect neutrino masses down to about – eV, whereas extended models suffer larger degeneracies raising the threshold to 0.16–0.19 eV. The study highlights the importance of including redshift evolution, BAO information, and rigorous MCMC analysis, and situates these cosmological constraints in the context of laboratory experiments like KATRIN and other future probes.

Abstract

We calculate the sensitivity of future cosmic microwave background probes and large scale structure measurements from galaxy redshift surveys to the neutrino mass. We find that, for minimal models with few parameters, a measurement of the matter power spectrum over a large range of redshifts has more constraining power than a single measurement at low redshifts. However, this improvement in sensitivity does not extend to larger models. We also quantify how the non-Gaussian nature of the posterior distribution function with respect to the individual cosmological parameter influences such quantities as the sensitivity and the detection threshold. For realistic assumptions about future large scale structure data, the minimum detectable neutrino mass at 95 % C.L. is about 0.05 eV in the context of a minimal 8-parameter cosmological model. In a more general model framework, however, the detection threshold can increase by as much as a factor of three.

Paper Structure

This paper contains 12 sections, 18 equations, 4 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Fiducial models
  3. Mock data and parameter error forecast
  4. Galaxy power spectrum
  5. Mock survey parameters
  6. Mock power spectrum data and the likelihood function
  7. Window functions
  8. Mock CMB data
  9. Results
  10. Sensitivity
  11. Detection threshold
  12. Conclusions

Figures (4)

  • Figure 1: The power spectrum suppression factor $P(k,z)/P_{m_\nu=0}(k,z)$ as a function of wavenumber $k$ and redshift $z$ for a neutrino mass of $\sum m_\nu = 0.08$ eV. The shadings are from 0.96 (darkest) to 1.00 (lightest) in steps of 0.005.
  • Figure 2: Projected 1D marginalised 95 % confidence regions for various cosmological parameters within the 8- and 10-parameter models, using various combinations of Planck and mock galaxy surveys. In each subplot, the data sets under consideration are, from top to bottom, Planck+G1, Planck+G2, Planck+SG, Planck+G1+G2, Planck+G1+SG, and Planck+G1+G2+SG. Solid lines denote constraints in the context of the 8-parameter model, while dotted lines refer to the 10-parameter model.
  • Figure 3: Same as Figure \ref{['fig:sigma']}, but with power spectrum smoothing as described in section \ref{['sec:windowfunctions']}, i.e., no BAO extraction.
  • Figure 4: The projected 1D marginalised 95 % confidence range for $\sum m_\nu$ as a function of the fiducial $\sum m_\nu$ for Planck+G1+G2+SG with BAO extraction. The light shaded band denotes the 10-parameter model, while the dark band corresponds to the 8-parameter model.