SLOW IV: Not all that is Close will Merge in the End. Superclusters and their Lagrangian collapse regions

TL;DR

This paper investigates the dynamics and bound regions of local superclusters using constrained simulations, revealing insights into their structure, evolution, and potential observational targets in the universe.

Contribution

It introduces a detailed analysis of supercluster collapse regions in the local universe using the SLOW simulation, linking large-scale structure to cluster evolution.

Findings

Superclusters are accurately reproduced in mass and geometry in the simulation.

Bound regions of superclusters are consistent with theoretical expectations.

Simulations identify potential observational features like bridges and collapsing filaments.

Abstract

Superclusters are the most massive structures in the universe. To what degree they are actually bound against an accelerating expansion of the background is of significant cosmological and astrophysical interest. In this study, we introduce a cross matched set of superclusters from the SLOW constrained simulations of the local (z<0.05) universe. Identifying the superclusters provides estimates on the efficacy of the constraints in reproducing the local large-scale structure accurately. The simulated counterparts can help identifying possible future observational targets containing interesting features such as bridges between pre-merging and merging galaxy clusters and collapsing filaments and provide comparisons for current observations. By determining the collapse volumes for the superclusters we further elucidate the dynamics of cluster-cluster interactions in those regions. Using catalogs of local superclusters and the most massive simulated clusters, we search for counterparts of supercluster members of six regions. We evaluate the significance of these detections by comparing their geometries to supercluster regions in random simulations. We then run an N-body version of the simulation into the far future and determine which of the member clusters are gravitationally bound to the host superclusters. Furthermore we compute masses and density contrasts for the collapse regions. We demonstrate the SLOW simulation of the local universe to accurately reproduce local supercluster regions in mass of their members and three-dimensional geometrical arrangement. We furthermore find the bound regions of the local superclusters consistent in size and density contrast with previous theoretical studies. This will allow to connect future numerical zoom-in studies of the clusters to the large scale environments and specifically the supercluster environments these local galaxy clusters evolve in.