Constraining massive neutrinos using cosmological 21 cm observations

TL;DR

This paper investigates how future 21 cm cosmological observations during reionization can significantly improve constraints on neutrino masses, potentially surpassing galaxy surveys and even distinguishing individual neutrino masses.

Contribution

It demonstrates the potential of 21 cm experiments to constrain neutrino masses more tightly than galaxy surveys and explores measuring individual neutrino masses.

Findings

21 cm observations can outperform galaxy surveys in neutrino mass constraints

Smaller scales and larger volumes improve neutrino mass limits

Future 21 cm experiments could measure individual neutrino masses

Abstract

Observations of neutrino oscillations show that neutrinos have mass. However, the best constraints on this mass currently come from cosmology, via measurements of the cosmic microwave background and large scale structure. In this paper, we explore the prospects for using low-frequency radio observations of the redshifted 21 cm signal from the epoch of reionization to further constrain neutrino masses. We use the Fisher matrix formalism to compare future galaxy surveys and 21 cm experiments. We show that by pushing to smaller scales and probing a considerably larger volume 21 cm experiments can provide stronger constraints on neutrino masses than even very large galaxy surveys. Finally, we consider the possibility of going beyond measurements of the total neutrino mass to constraining the mass hierarchies. For a futuristic, 21 cm experiment we show that individual neutrino masses could be measured separately from the total neutrino mass.