Characterizing the bulk and turbulent gas motions in galaxy clusters

TL;DR

This paper investigates the bulk and turbulent gas motions in galaxy clusters using X-ray and Sunyaev-Zel'dovich effect data, aiming to understand their role in cluster formation, evolution, and non-thermal pressure contributions.

Contribution

It provides a comprehensive analysis of gas motions across a wide range of cluster redshifts, masses, and dynamical states, utilizing multiple observational samples and studying their self-similar behavior.

Findings

Gas motions contribute significantly to non-thermal pressure in clusters.

Dynamical state influences the properties of gas motions.

Evidence for self-similar behavior in gas motions across clusters.

Abstract

The most massive halos of matter in the Universe grow via accretion and merger events throughout cosmic times. These violent processes generate shocks at many scales and induce large-scale bulk and turbulent motions. These processes inject kinetic energy at large scales, which is transported to the viscous dissipation scales, contributing to the overall heating and virialisation of the halo, and acting as a source of non-thermal pressure in the intra-cluster medium. Characterizing the physical properties of these gas motions will help us to better understand the assembly of massive halos, hence the formation and the evolution of these large-scale structures. We base this characterization on the study of the X-ray and Sunyaev-Zel'dovich effect brightness fluctuations. Our work relies on three complementary samples covering a wide range of redshifts, masses and dynamical states of clusters. We present the results of our X-ray analysis for the low redshift sample, X-COP, and a subsample of higher redshift clusters. We investigate the derived properties according to the dynamical state of our clusters, and the possibility of a self-similar behaviour based on the reconstructed gas motions power-spectra and the correlation with various morphological indicators.