Internal dark matter structure of the most massive galaxy clusters since redshift 1

Amandine M C Le Brun,Romain Teyssier

doi:10.1051/epjconf/202225700026

Abstract

We investigate the evolution of the dark matter density profiles of the most massive galaxy clusters in the Universe. Using a ‘zoom-in’ procedure on a large suite of cosmological simulations of total comoving volume of 3 (h-1 Gpc)3, we study the 25 most massive clusters in four redshift slices from z ~ 1 to the present. The minimum mass is M500 > 5:5 × 1014 M⊙ at z = 1. Each system has more than two million particles within r500. Once scaled to the critical density at each redshift, the dark matter profiles within r500 are strikingly similar from z ~ 1 to the present day, exhibiting a low dispersion of 0.15 dex, and showing little evolution with redshift in the radial logarithmic slope and scatter. They have the running power law shape typical of the NFW-type profiles, and their inner structure, resolved to 3:8 h-1 comoving kpc at z = 1, shows no signs of converging to an asymptotic slope. Our results suggest that this type of profile is already in place at z > 1 in the highest-mass haloes in the Universe, and that it remains exceptionally robust to merging activity.

Highlights

This proceeding is entirely based upon [18] and M∆ is always the mass within radius r∆, the radius within which the mean mass density is ∆ times the critical density at the cluster redshift
We have focussed in this work on the dark matter density profiles of the 25 most massive systems selected from dark matter only (DMO) simulations in four redshift slices
With a median mass of M500 = 6.3 ⇥ 1014 M at z = 1, the sample is composed of the rarest objects, probing for the first time the extreme limits of the cluster mass function, such as would be detectable observationally only in all-sky surveys

Summary

Introduction

This proceeding is entirely based upon [18] and M∆ is always the mass within radius r∆, the radius within which the mean mass density is ∆ times the critical density at the cluster redshift. Being mostly dark matter-dominated, they have deep potential wells and gravity is the dominant mechanism driving their evolution They are least a↵ected by complex non-gravitational galaxy formation processes [e.g. 5–7]. They are detectable up to high redshift, and complementary techniques can probe both their internal structure and global properties. They are perfect objects for testing these theories. Existing simulations are ill-suited for studying high-mass, high redshift systems, as oft their resolution is scant, and/or simulated objects are in short supply. This study extends existing works on the shape of massive dark matter haloes [15–17] by augmenting the spatial or mass resolution and the amount of systems.

Simulations and data processing

Results

Discussion and conclusion