Simulations of Precessing Jets and the Formation of X-shaped Radio Galaxies

TL;DR

This paper uses simulations to explore how jet precession in radio galaxies influences their observed shapes, revealing that viewing angles and jet instabilities can cause diverse morphologies and phenomena like reorientation events and Odd Radio Circles.

Contribution

The study provides the first detailed simulations of precessing jets with cosmic ray electron modeling, showing how viewing angles and jet dynamics affect radio galaxy morphology.

Findings

Different viewing angles produce varied RG classifications.

Jet self-interactions can cause reorientation events.

Precessing jets may produce observable Odd Radio Circles.

Abstract

Jet precession is sometimes invoked to explain asymmetries in radio galaxy (RG) jets and "X/S/Z-shape" radio galaxies, caused by the presence of a binary black hole companion to the source active galactic nucleus (AGN) or by accretion instabilities. We present a series of simulations of radio galaxy jet precession to examine how these sources would evolve over time, including a passive distribution of cosmic ray electrons (CRe) so we can model radio synchrotron emissions and create synthetic radio maps of the sources. We find that a single source viewed from different angles can result in differing RG morphological classifications, confusing physical implications of these classifications. Additionally, the jet trajectories can become unstable due to their own self-interactions and lead to "reorientation events" that may look like the effects of external dynamics such as shocks, winds, or cold fronts in the medium. Finally, something akin to an "Odd Radio Circle" may be observed in the case of viewing the radio remnant of such a precessing source from a line of sight near the precession axis.