2D watershed void clustering for probing the cosmic large-scale structure

TL;DR

This paper introduces a novel 2D watershed void clustering method using Voronoi tessellation to probe the large-scale structure of the universe, providing competitive cosmological constraints for future high-redshift surveys.

Contribution

It develops a new 2D void identification technique and a theoretical model, demonstrating its effectiveness in extracting cosmological information from high-redshift galaxy surveys.

Findings

2D void clustering constraints are comparable to galaxy clustering constraints.

Joint analysis improves parameter constraints by up to 30%.

Method is effective for high-redshift, low-density galaxy surveys.

Abstract

Cosmic void has been proven to be an effective cosmological probe of the large-scale structure (LSS). However, since voids are usually identified in spectroscopic galaxy surveys, they are generally limited to low number density and redshift. We propose to utilize the clustering of two-dimensional (2D) voids identified using Voronoi tessellation and watershed algorithm without any shape assumption to explore the LSS. We generate mock galaxy and void catalogs for the next-generation Stage IV photometric surveys in $z = 0.8-2.0$ from simulations, develop the 2D void identification method, and construct the theoretical model to fit the 2D watershed void and galaxy angular power spectra. We find that our method can accurately extract the cosmological information, and the constraint accuracies of some cosmological parameters from the 2D watershed void clustering are even comparable to the galaxy angular clustering case, which can be further improved by as large as $\sim30\%$ in the void and galaxy joint constraints. This indicates that the 2D void clustering is a good complement to galaxy angular clustering measurements, especially for the forthcoming Stage IV surveys that detect high-redshift universe.