The impact of flickering variability and magnetisation on the dynamics, stability and morphology of radio-loud AGN jets

TL;DR

This study uses relativistic magnetohydrodynamic simulations to explore how magnetization and flickering jet power influence the morphology, stability, and instabilities of radio-loud AGN jets, revealing their significant roles.

Contribution

It introduces a comprehensive simulation library demonstrating the combined effects of magnetization and variability on jet morphology and stability, advancing understanding of AGN jet physics.

Findings

High magnetization causes asymmetric cocoon morphologies.

Variable high magnetization jets can develop broken morphologies.

Magnetization and variability influence jet stability and instabilities.

Abstract

The physics governing the morphology of radio-loud AGN jets is not fully understood. We investigate how magnetization, flickering jet power and their interplay affects the morphology of radio galaxies. We present a grid of relativistic magnetohydrodynamic simulations using the PLUTO code covering constant and variable jets with two levels of magnetisation. We find that the constant high magnetisation jets can lead to highly asymmetrical cocoon morphologies, whilst the variable high magnetisation jet can exhibit a broken morphology, caused by a discontinuous jet beam. Our work highlights the importance of magnetisation and variability on the stability and resulting morphology of radio-loud AGN jets, suggesting both are significant factors in addition to jet power or environment. Furthermore, we show that the interaction between magnetisation and variability can lead to the development of localised kink instabilities along the jet beam. Finally, we discuss the effects of hydrodynamic mixing in low magnetisation jets and the role of viewing angle dependence in comparisons between our simulations and observed sources. To facilitate this comparison we present a library of simulated radio images at different times in the simulations and from various viewing angles, which highlight a diverse set of complex morphologies.