Cosmology with Void-Galaxy Correlations

TL;DR

This paper proposes using galaxy-void cross correlations to calibrate galaxy bias and establish a static cosmological ruler, leveraging the geometric properties of voids for improved large-scale structure analysis.

Contribution

It introduces a novel method of using galaxy-void correlations to calibrate galaxy bias and measure cosmological parameters, which was not previously explored.

Findings

Galaxy-void cross correlations can calibrate galaxy bias.

Void clustering relates to mass compensation and volume exclusion.

Galaxy distribution inside voids matches mass-density profiles.

Abstract

Galaxy bias, the unknown relationship between the clustering of galaxies and the underlying dark matter density field is a major hurdle for cosmological inference from large-scale structure. While traditional analyses focus on the absolute clustering amplitude of high-density regions mapped out by galaxy surveys, we propose a relative measurement that compares those to the underdense regions, cosmic voids. On the basis of realistic mock catalogs we demonstrate that cross correlating galaxies and voids opens up the possibility to calibrate galaxy bias and to define a static ruler thanks to the observable geometric nature of voids. We illustrate how the clustering of voids is related to mass compensation and show that volume-exclusion significantly reduces the degree of stochasticity in their spatial distribution. Extracting the spherically averaged distribution of galaxies inside voids from their cross correlations reveals a remarkable concordance with the mass-density profile of voids.