Numerical modelling of the lobes of radio galaxies -- Paper V: Universal Pressure Profile cluster atmospheres

TL;DR

This paper introduces relativistic magnetohydrodynamic simulations of radio galaxy lobes within realistic cluster atmospheres modeled by the Universal Pressure Profile, providing insights into jet-lobe dynamics and morphology.

Contribution

First numerical simulation using UPP-based atmospheres to study AGN jets, revealing effects on lobe morphology, energy distribution, and the role of instabilities.

Findings

UPP atmospheres produce more realistic lobe structures.

Cluster environment influences energy distribution in lobes.

Kelvin-Helmholtz instabilities are crucial for lobe aspect ratios.

Abstract

We present relativistic magnetohydrodynamic modelling of jets running into hydrostatic, spherically symmetric cluster atmospheres. For the first time in a numerical simulation, we present model cluster atmospheres based upon the Universal Pressure Profile (UPP), incorporating a temperature profile for a typical self-similar atmosphere described by only one parameter - $M_{500}$. We explore a comprehensive range of realistic atmospheres and jet powers and derive dynamic, energetic and polarimetric data which provide insight into what we should expect of future high-resolution studies of AGN outflows. From the simulated synchrotron emission maps which include Doppler beaming we find sidedness distributions that agree well with observations. We replicated a number of findings from our previous work, such as higher power jets inflating larger aspect-ratio lobes and the cluster environment impacting the distribution of energy between the lobe and shocked regions. Comparing UPP and $\beta$-profiles we find that the cluster model chosen results in a different morphology for the resultant lobes with the UPP more able to clear lobe material from the core; and that these different atmospheres influence the ratio between the various forms of energy in the fully developed lobes. This work also highlights the key role played by Kelvin-Helmholtz (KH) instabilities in the formation of realistic lobe aspect-ratios. Our simulations point to the need for additional lobe-widening mechanisms at high jet powers, for example jet precession. Given that the UPP is our most representative general cluster atmosphere, these numerical simulations represent the most realistic models yet for spherically symmetric atmospheres.