Dark Sector Coupling Bends the Superclusters

TL;DR

This study investigates how dark sector coupling influences the shape of superclusters, finding that coupled dark energy models tend to produce less straight superclusters than the standard LCDM model, especially at higher redshifts.

Contribution

It introduces a novel method to quantify supercluster straightness and demonstrates its sensitivity to dark energy coupling models using cosmological simulations.

Findings

Dark sector coupling reduces supercluster straightness compared to LCDM.

Supercluster straightness difference increases with redshift.

Supergravity potential cDE models produce the least straight superclusters.

Abstract

The galaxy clusters exhibit noticeably anisotropic pattern in their clustering, which is vividly manifested by the presence of rich filament-like superclusters. The more anisotropic the clustering of galaxy clusters is, the more straight the rich filament-like superclusters become. Given that the degree of the anisotropy in the largest-scale clustering depends sensitively on the nature of dark energy, the supercluster straightness may play a complimentary role in testing dynamic dark energy models. Here we focus on the coupled dark energy (cDE) models which assume the existence of dark sector coupling between scalar field dark energy and nonbaryonic dark matter. Determining the spines of the superclusters identified in the publicly available group catalogs from the CODECS (COupled Dark Energy Cosmological Simulations) for four different cDE models as well as for the LCDM model, we quantify the straightness of each supercluster as the spatial extent of its spine per member cluster where a supercluster spine represents the main stem of the minimal spanning tree constructed out of the member clusters. It is shown that the dark sector coupling plays a role in making the supercluster less straight relative to the LCDM case and that in a cDE model with supergravity potential the superclusters are least straight. We also find that the difference in the degree of the supercluster straightness between the cDE and the LCDM cases increases with redshifts. A physical interpretation of our result as well as its cosmological implication are discussed.