Voids as a Precision Probe of Dark Energy

TL;DR

This paper proposes using the ellipticity distribution of cosmic voids as a novel method to constrain dark energy parameters, showing promising improvements when combined with traditional techniques.

Contribution

It introduces a new approach leveraging void ellipticities from future surveys to improve dark energy constraints, including systematic effects analysis.

Findings

Void ellipticity distribution is sensitive to cosmological parameters.

Combining void data with traditional methods significantly enhances dark energy constraints.

Systematic uncertainties can impact the precision of these constraints.

Abstract

A signature of the dark energy equation of state may be observed in the shape of voids. We estimate the constraints on cosmological parameters that would be determined from the ellipticity distribution of voids from future spectroscopic surveys already planned for the study of large scale structure. The constraints stem from the sensitivity of the distribution of ellipticity to the cosmological parameters through the variance of fluctuations of the density field smoothed at some length scale. This length scale can be chosen to be of the order of the comoving radii of voids at very early times when the fluctuations are Gaussian distributed. We use Fisher estimates to show that the constraints from void ellipticities are promising. Combining these constraints with other traditional methods results in the improvement of the Dark Energy Task Force Figure of Merit on the dark energy parameters by an order of hundred for future experiments. The estimates of these future constraints depend on a number of systematic issues which require further study using simulations. We outline these issues and study the impact of certain observational and theoretical systematics on the forecasted constraints on dark energy parameters.