Gravitational Lensing Effect on the Two-Point Correlation Function of Hot Spots in 21 cm fluctuations

TL;DR

This paper studies how weak gravitational lensing affects the two-point correlation function of hot spots in 21 cm fluctuations, revealing potential for constraining dark energy properties.

Contribution

It demonstrates that weak lensing causes w-dependent smoothing of the correlation function's depression feature, offering a new method to probe dark energy.

Findings

Weak lensing induces significant smoothing at the depression scale.

The smoothing depends on the dark energy equation of state parameter w.

This effect can help constrain dark energy properties.

Abstract

We investigate the weak gravitational lensing effect on the two-point correlation function of local maxima (hot spots) in the cosmic 21 cm fluctuation map. The intrinsic two-point function has a pronounced depression feature around the angular scale of $\theta \sim 40$ arcmin, which depends on the observed frequency and corresponds to the scale of the acoustic oscillation of cosmic plasma before the recombination. It is found that the weak lensing induces a large w-dependent smoothing at that scale where w is the equation of state parameter of dark energy and thus provides a useful constraints on the dark energy property combined with the depression angular scales on the two-point correlation function.