Plasma 2020 - Intracluster Medium Plasmas

TL;DR

This paper reviews the properties and dynamics of the intracluster medium in galaxy clusters, emphasizing plasma processes, magnetic fields, and high-energy particle transport observed via X-ray and radio methods.

Contribution

It provides a comprehensive overview of kinetic-scale plasma processes and their role in shaping the intracluster medium's behavior and observable phenomena.

Findings

Kinetic plasma processes are fundamental to ICM dynamics.

Cluster mergers and feedback drive turbulence and shocks.

Magnetic fields influence high-energy particle transport.

Abstract

Galaxy clusters are the largest and most massive bound objects resulting from cosmic hierarchical structure formation. Baryons account for somewhat more than 10% of that mass, with roughly 90% of the baryonic matter distributed throughout the clusters as hot ($T>1$ keV), high-$\beta$, very weakly collisional plasma; the so-called "intracluster medium" (ICM). Cluster mergers, close gravitational encounters and accretion, along with violent feedback from galaxies and relativistic jets from active galactic nuclei, drive winds, gravity waves, turbulence and shocks within the ICM. Those dynamics, in turn, generate cluster-scale magnetic fields and accelerate and mediate the transport of high-energy charged particles. Kinetic-scale, collective plasma processes define the basic character and fundamental signatures of these ICM phenomena, which are observed primarily by X-ray and radio astronomers.