The Weight of Emptiness: The Gravitational Lensing Signal of Stacked Voids

TL;DR

This paper explores how future galaxy surveys can detect gravitational lensing signals from cosmic voids by stacking large samples, enabling direct measurement of matter distribution around voids.

Contribution

It demonstrates the potential of upcoming surveys to measure void lensing signals through stacking, independent of galaxy bias assumptions.

Findings

Void lensing signals detectable with Stage IV surveys.

Stacking improves statistical precision significantly.

Provides direct constraints on matter density profiles.

Abstract

The upcoming new generation of spectroscopic galaxy redshift surveys will provide large samples of cosmic voids, the distinct, large underdense structures in the universe. Combining these with future galaxy imaging surveys, we study the prospects of probing the underlying matter distribution in and around cosmic voids via the weak gravitational lensing effects of stacked voids, utilizing both shear and magnification information. The statistical precision is greatly improved by stacking together a large number of voids along different lines of sight, even when taking into account the impact of inherent miscentering and projection effects. We show that Dark Energy Task Force Stage IV surveys, such as the Euclid satellite and the Large Synoptic Survey Telescope, should be able to detect the void lensing signal with sufficient precision from stacking abundant medium-sized voids, thus providing direct constraints on the matter density profile of voids independent of assumptions on galaxy bias.