Jet Interactions with the Hot Halos of Clusters and Galaxies

TL;DR

X-ray observations of jets and hot halos reveal their energetics, dynamics, and impact on galaxy clusters, showing that radio sources can regulate cooling and exhibit diverse efficiencies and ages.

Contribution

This paper synthesizes X-ray observational data to analyze jet interactions with hot halos, highlighting their energetic contributions and dynamic properties in galaxy clusters.

Findings

Jets release enough energy to regulate halo cooling.

Radio source power scales with synchrotron luminosity.

Synchrotron ages are decoupled from dynamical ages.

Abstract

X-ray observations of cavities and shock fronts produced by jets streaming through hot halos have significantly advanced our understanding of the energetics and dynamics of extragalactic radio sources. Radio sources at the centers of clusters have dynamical ages between ten and several hundred million years. They liberate between 1E58-1E62 erg per outburst, which is enough energy to regulate cooling of hot halos from galaxies to the richest clusters. Jet power scales approximately with the radio synchrotron luminosity to the one half power. However, the synchrotron efficiency varies widely from nearly unity to one part in 10,000, such that relatively feeble radio source can have quasar-like mechanical power. The synchrotron ages of cluster radio sources are decoupled from their dynamical ages, which tend to be factors of several to orders of magnitude older. Magnetic fields and particles in the lobes tend to be out of equipartition. The lobes may be maintained by heavy particles (e.g., protons), low energy electrons, a hot, diffuse thermal gas, or possibly magnetic (Poynting) stresses. Sensitive X-ray images of shock fronts and cavities can be used to study the dynamics of extragalactic radio sources.