Probing dark energy using anisotropies in the clustering of post-EoR HI distribution

TL;DR

This paper introduces an anisotropy-based method using the HI 21-cm signal to probe dark energy, demonstrating measurable signals and potential constraints on models with negative cosmological constants.

Contribution

It proposes a novel anisotropy quantifier for the HI 21-cm signal as a dark energy diagnostic and explores its application to constrain complex dark energy models.

Findings

Anisotropy probe measurable at SNR ~10 in auto- and cross-correlation.

BAO features in anisotropy can determine H(z) and D_A(z).

Constraints on dark energy models with negative cosmological constant.

Abstract

We propose an anisotropy quantifier of the HI 21-cm signal traditionally used to clock the astrophysics of the reionization era as a post-reionization dark energy diagnostic. We find that the anisotropy probe can be measured at SNR $\sim 10$ in both auto-correlation and in cross-correlation with the Ly-$\alpha$ forest over a wide $z$ and $k-$range. We propose to use the BAO signature on the anisotropy signal to measure $( H(z), D_A(z))$. Subsequently, we put constraints on a dark energy model involving a negative cosmological constant on top of a quintessence scalar field and find that such a model is consistent with futuristic observations.