The redshifted HI 21 cm signal from the post-reionization epoch: Cross-correlations with other cosmological probes

TL;DR

This paper explores the potential of cross-correlating the post-reionization 21 cm hydrogen signal with other cosmological probes to enhance understanding of structure formation and cosmological parameters.

Contribution

It investigates the feasibility of detecting the post-reionization 21 cm signal through cross-correlations with multiple large-scale structure tracers and CMB anisotropies.

Findings

Cross-correlation signals are potentially detectable with upcoming radio telescopes.

The method can constrain cosmological models and parameters.

Combining signals improves understanding of structure formation.

Abstract

Tomographic intensity mapping of the HI using the redshifted 21 cm observations opens up a new window towards our understanding of cosmological background evolution and structure formation. This is a key science goal of several upcoming radio telescopes including the Square Kilometer Array (SKA). In this article we focus on the post-reionization signal and investigate the of cross correlating the 21 cm signal with other tracers of the large scale structure. We consider the cross-correlation of the post-reionization 21 cm signal with the Lyman-alpha forest, Lyman-break galaxies and late time anisotropies in the CMBR maps like weak lensing and the Integrated Sachs Wolfe effect. We study the feasibility of detecting the signal and explore the possibility of obtaining constraints on cosmological models using it.