Galaxy clusters in local Universe simulations without density constraints: a long uphill struggle

TL;DR

This paper presents a novel simulation method that uses only radial peculiar velocities to produce realistic local Universe cluster simulations, enabling detailed studies of local clusters like Coma without density constraints.

Contribution

The method uniquely relies solely on radial velocities for constraints, improving local cluster simulation accuracy without additional density data.

Findings

Simulations successfully reproduce prominent local clusters like Coma.

New velocity modeling reduces mass and data constraint correlations.

Enables zoom-in studies of local clusters and their effects.

Abstract

Galaxy clusters are excellent cosmological probes provided that their formation and evolution within the large scale environment are precisely understood. Therefore studies with simulated galaxy clusters have flourished. However detailed comparisons between simulated and observed clusters and their population - the galaxies - are complicated by the diversity of clusters and their surrounding environment. An original way initiated by Bertschinger as early as 1987, to legitimize the one-to-one comparison exercise down to the details, is to produce simulations constrained to resemble the cluster under study within its large scale environment. Subsequently several methods have emerged to produce simulations that look like the local Universe. This paper highlights one of these methods and its essential steps to get simulations that not only resemble the local Large Scale Structure but also that host the local clusters. It includes a new modeling of the radial peculiar velocity uncertainties to remove the observed correlation between the decreases of the simulated cluster masses and of the amount of data used as constraints with the distance from us. This method has the particularity to use solely radial peculiar velocities as constraints: no additional density constraints are required to get local cluster simulacra. The new resulting simulations host dark matter halos that match the most prominent local clusters such as Coma. Zoom-in simulations of the latter and of a volume larger than the 30 Mpc/h radius inner sphere become now possible to study local clusters and their effects. Mapping the local Sunyaev-Zel'dovich and Sachs-Wolfe effects can follow.