Modeling the Outskirts of Galaxy Clusters with Cosmological Simulations

TL;DR

This paper uses cosmological simulations to study the outskirts of galaxy clusters, revealing how cosmic accretion, mergers, and gas motions affect ICM properties and measurement biases, with implications for cosmology.

Contribution

It provides new insights into the impact of large-scale accretion and gas motions on ICM inhomogeneity and biases in cluster measurements.

Findings

Gas motions cause significant non-thermal pressure in ICM.

Accretion and mergers induce gas clumpiness and inhomogeneity.

Non-thermal pressure affects CMB secondary anisotropies.

Abstract

We present cosmological simulations of galaxy clusters, with focus on the cluster outskirts. We show that large-scale cosmic accretion and mergers produce significant internal gas motions and inhomogeneous gas distribution ("clumpiness") in the intracluster medium (ICM) and introduce biases in measurements of the ICM profiles and the cluster mass. We also show that non-thermal pressure provided by the gas motions is one of the dominant sources of theoretical uncertainties in cosmic microwave background secondary anisotropies. We briefly discuss implications for cluster cosmology and future prospects for understanding the physics of cluster outskirts using computer simulations and multi-wavelength cluster surveys.