Neutrino Mass Inference from SZ Surveys

TL;DR

This paper investigates how SZ cluster surveys from experiments like PLANCK, SPT, EPIC, and ACT can be used to constrain neutrino masses, providing forecasts for their measurement capabilities and limitations.

Contribution

It presents the first detailed forecasts of neutrino mass constraints achievable with current and upcoming SZ surveys, comparing their effectiveness and tradeoffs.

Findings

PLANCK SZ survey can measure neutrino mass with 0.28 eV uncertainty.

EPIC survey can achieve about 0.12 eV uncertainty.

Shallow surveys are preferable over deep ones for neutrino mass constraints.

Abstract

The growth of structure in the universe begins at the time of radiation-matter equality, which corresponds to energy scales of $\sim 0.4 eV$. All tracers of dark matter evolution are expected to be sensitive to neutrino masses on this and smaller scales. Here we explore the possibility of using cluster number counts and power spectrum obtained from ongoing SZ surveys to constrain neutrino masses. Specifically, we forecast the capability of ongoing measurements with the PLANCK satellite and the ground-based SPT experiment, as well as measurements with the proposed EPIC satellite, to set interesting bounds on neutrino masses from their respective SZ surveys. We also consider an ACT-like CMB experiment that covers only a few hundred ${\rm deg^{2}}$ also to explore the tradeoff between the survey area and sensitivity and what effect this may have on inferred neutrino masses. We find that for such an experiment a shallow survey is preferable over a deep and low-noise scanning scheme. We also find that projected results from the PLANCK SZ survey can, in principle, be used to determine the total neutrino mass with a ($1\sigma$) uncertainty of $0.28 eV$, if the detection limit of a cluster is set at the $5\sigma$ significance level. This is twice as large as the limits expected from PLANCK CMB lensing measurements. The corresponding limits from the SPT and EPIC surveys are $\sim 0.44 eV$ and $\sim 0.12 eV$, respectively. Mapping an area of 200 deg$^{2}$, ACT measurements are predicted to attain a $1\sigma$ uncertainty of 0.61 eV; expanding the observed area to 4,000 deg$^{2}$ will decrease the uncertainty to 0.36 eV.