Testing cosmic geometry without dynamic distortions using voids

TL;DR

This paper introduces a new method using cosmic voids' clustering statistics to measure the Universe's expansion history, minimizing systematic errors from redshift-space distortions.

Contribution

It presents a novel void-based Alcock-Paczynski test that reduces systematics and improves constraints on cosmic geometry compared to galaxy-based methods.

Findings

Void auto-correlations are minimally affected by peculiar motions.

The method provides a more precise and less biased measurement of cosmological parameters.

It offers the cleanest probe of cosmic geometry to date.

Abstract

We propose a novel technique to probe the expansion history of the Universe based on the clustering statistics of cosmic voids. In particular, we compute their two-point statistics in redshift space on the basis of realistic mock galaxy catalogs and apply the Alcock-Paczynski test. In contrast to galaxies, we find void auto-correlations to be marginally affected by peculiar motions, providing a model-independent measure of cosmological parameters without systematics from redshift-space distortions. Because only galaxy-galaxy and void-galaxy correlations have been considered in these types of studies before, the presented method improves both statistical and systematic uncertainties on the product of angular diameter distance and Hubble rate, furnishing the potentially cleanest probe of cosmic geometry available to date.