Abundances, masses, and weak-lensing mass profiles of galaxy clusters as a function of richness and luminosity in LambdaCDM cosmologies

TL;DR

This study compares galaxy cluster properties predicted by LambdaCDM cosmology using simulations with SDSS observations, finding good agreement in mass profiles but differences in abundance linked to cosmological parameters like sigma_8.

Contribution

It provides a detailed comparison of simulated and observed galaxy cluster properties across different cosmological models, highlighting the influence of sigma_8 on cluster abundance.

Findings

Simulated weak-lensing profiles match observed profiles well.

Cluster mass-richness relations are consistent within 30%.

Cluster abundance varies significantly with cosmological parameters.

Abstract

We test the concordance LCDM cosmology by comparing predictions for the mean properties of galaxy clusters to observations. We use high-resolution N-body simulations of cosmic structure formation and semi-analytic models of galaxy formation to compute the abundance, mean density profile, and mass of galaxy clusters as a function of richness and luminosity, and we compare these predictions to observations of clusters in the Sloan Digital Sky Survey (SDSS) maxBCG catalogue. We discuss the scatter in the mass-richness relation, the reconstruction of the cluster mass function from the mass-richness relation, and fits to the weak-lensing cluster mass profiles. The impact of cosmological parameters on the predictions is investigated by comparing results from galaxy models based on the Millennium Simulation (MS) and another WMAP1 simulation to those from a WMAP3 simulation. We find that the simulated weak-lensing mass profiles and the observed profiles of the SDSS maxBCG clusters agree well in shape and amplitude. The mass-richness relations in the simulations are close to the observed relation, with differences lesssim 30%. The MS and WMAP1 simulations yield cluster abundances similar to those observed, whereas abundances in the WMAP3 simulation are 2-3 times lower. The differences in cluster abundance, mass, and density amplitude between the simulations and the observations can be attributed to differences in the underlying cosmological parameters, in particular the power spectrum normalisation sigma_8. Better agreement between predictions and observations should be reached with a normalisation $0.722<sigma_8<0.9$ (probably closer to the upper value), i.e. between the values underlying the two simulation sets.