Cosmology with voids from the Nancy Grace Roman Space Telescope

TL;DR

This paper forecasts the potential of the Nancy Grace Roman Space Telescope's void statistics, like the void size function and void-galaxy cross-correlation, to constrain cosmological models such as ΛCDM, wCDM, and w0waCDM.

Contribution

It provides the first detailed forecast of Roman's void-based cosmological constraints using realistic mock data and explores their complementarity across different void statistics.

Findings

Over 80,000 voids expected in the survey volume.

Void statistics show strong complementarity in constraining cosmological models.

Roman's high tracer density enhances its constraining power.

Abstract

We provide an accurate forecast of the expected constraining power from the main void statistics -- the void size function and the void-galaxy cross-correlation function -- to be measured by the Roman reference High Latitude Spectroscopic Survey from the Nancy Grace Roman Space Telescope. Relying on a realistic galaxy mock lightcone, covering 2000 square degrees, we find more than $8\times 10^4 $ voids and explore their constraining power in the framework of three different cosmological models: $\Lambda$CDM, $w$CDM, and $w_0 w_{\rm a}$CDM. This work confirms the strong complementarity of different void statistics and showcases the constraining power to be expected from Roman voids thanks to the combination of its high tracer density and large observed volume.