Formation of X-Ray Cavities by the Magnetically Dominated Jet-Lobe System in a Galaxy Cluster

TL;DR

This study uses cosmological magnetohydrodynamic simulations to show that magnetically dominated jet-lobe systems can create X-ray cavities in galaxy clusters, with magnetic energy playing a key role in their formation and evolution.

Contribution

It demonstrates that X-ray cavities are magnetically dominated and formed by a central axial current, highlighting the magnetic fields' role in cavity morphology and dynamics.

Findings

X-ray cavities are magnetically dominated structures.

Up to 80-90% of magnetic energy heats and lifts the cluster medium.

Cavities are driven by magnetic Lorentz forces and become buoyant after 500 Myr.

Abstract

We present cosmological magnetohydrodynamic simulations of the formation of a galaxy cluster with magnetic energy feedback from an active galactic nuclei (AGN). We demonstrate that X-ray cavities can be produced by the magnetically dominated jet-lobe system that is supported by a central axial current. The cavities are magnetically dominated and their morphology is determined jointedly by the magnetic fields and the background cluster pressure profile. The expansion and motion of the cavities are driven initially by the Lorentz force of the magnetic fields, and the cavities only become buoyant at late stages ($> 500$ Myr). We find that up to $80%-90%$ of the injected magnetic energy goes into doing work against the hot cluster medium, heating it, and lifting it in the cluster potential.