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

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.