Reconstructing large scales at cosmic dawn

TL;DR

This paper explores how kSZ tomography, using cross correlations between CMB temperature and 21cm surveys, can enhance understanding of inhomogeneous reionization and recover large-scale modes obscured by foreground contamination.

Contribution

It demonstrates the potential of kSZ tomography to improve constraints on reionization models and recover large-scale modes not accessible through 21cm measurements alone.

Findings

kSZ tomography improves constraints on reionization models

enables recovery of large-scale modes affected by foregrounds

demonstrates significant potential for cosmic dawn studies

Abstract

The cosmic microwave background (CMB) serves as a backlight to large-scale structure during the epoch of reionization, where Thomson scattering gives rise to temperature anisotropies on small angular scales from the kinetic Sunyaev Zel'dovich (kSZ) effect. In this paper, we demonstrate that the technique of kSZ tomography (velocity reconstruction), based on cross correlations between CMB temperature and 21cm surveys, can significantly improve constraints on models of inhomogeneous reionization and provide information about large-scale modes that are poorly characterized by 21cm measurements themselves due to foreground contamination.