Possibility of Precise Measurement of the Cosmological Power Spectrum With a Dedicated 21cm Survey After Reionization

TL;DR

This paper explores how a dedicated 21cm survey after reionization could precisely measure the cosmological power spectrum, detect neutrino mass, and constrain theories of gravity and dark energy with unprecedented accuracy.

Contribution

It demonstrates the potential of a specialized 21cm observatory to vastly increase the number of measurable modes and improve cosmological parameter constraints.

Findings

Probe a hundred times more modes than current methods.

Enable detection of neutrino mass around 0.05 eV.

Constrain dark energy and gravity theories with high precision.

Abstract

Measurements of the 21cm line emission by residual cosmic hydrogen after reionization can be used to trace the power spectrum of density perturbations through a significant fraction of the observable volume of the Universe. We show that a dedicated 21cm observatory coule probe a number of independent modes that is two orders of magnitude larger than currently available, and enable a cosmic-variance limited detection of the signature of a neutrino mass ~0.05eV. The evolution of the linear growth factor with redshift could also constrain exotic theories of gravity or dark energy to an unprecedented precision.