Constraints on Neutrino Mass from Sunyaev--Zeldovich Cluster Surveys

TL;DR

This paper forecasts how upcoming Sunyaev-Zeldovich cluster surveys, combined with CMB data, can significantly improve constraints on the total neutrino mass, highlighting the importance of systematics control and combined probes.

Contribution

It demonstrates that SZ cluster surveys combined with CMB observations can tighten neutrino mass constraints and explores the impact of survey specifications and systematics control.

Findings

Cluster surveys plus CMB can reduce neutrino mass error to 0.08 eV.

Combining number counts and power spectrum improves constraints by a factor of 4-8.

Good control of systematics is crucial for tight neutrino mass constraints.

Abstract

The presence of massive neutrinos has a characteristic impact on the growth of large scale structures such as galaxy clusters. We forecast on the capability of the number count and power spectrum measured from the ongoing and future Sunyaev-Zeldovich (SZ) cluster surveys, combined with cosmic microwave background (CMB) observation to constrain the total neutrino mass $\mnu$ in a flat $\Lambda$CDM cosmology. We adopt self-calibration for the mass-observable scaling relation, and evaluate constraints for the South Pole Telescope normal and with polarization (SPT, SPTPol), Planck, and Atacama Cosmology Telescope Polarization (ACTPol) surveys. We find that a sample of $\approx1000$ clusters obtained from the Planck cluster survey plus extra information from CMB lensing extraction could tighten the current upper bound on the sum of neutrino masses to $\sigma_{\mnu}=0.17$ eV at 68% C.L. Our analysis shows that cluster number counts and power spectrum provide complementary constraints and as a result they help reducing the error bars on $\mnu$ by a factor of 4-8 when both probes are combined. We also show that the main strength of cluster measurements in constraining $\mnu$ is when good control of cluster systematics is available. When applying a weak prior on the mass-observable relations, which can be at reach in the upcoming cluster surveys, we obtain $\sigma_{\mnu}=0.48$ eV using cluster only probes and, more interestingly, $\sigma_{\mnu}=0.08$ eV using cluster + CMB which corresponds to a $S/N\approx4$ detection for $\mnu\ge0.3$ eV. We analyze and discuss the degeneracies of $\mnu$ with other parameters and investigate the sensitivity of neutrino mass constraints with various surveys specifications.