Origin of the ∼150 kpc radio filament in galaxy ESO 137−006

Abstract

Sensitive wide-field radio surveys have started uncovering many filamentary structures associated with the jets and lobes of radio galaxies, radio relics in galaxy clusters, and tailed galaxies. Although limited theoretical investigations on the origin of the filamentary structures have associated these filaments with astrophysical shocks and interactions with intracluster magneto-ionic media, more quantitative studies are needed to ascertain their precise nature and origin. Recent MeerKAT observations found peculiar filamentary structures (threaded radio structures) joining the lobes of a nearby FR II-like galaxy, ESO 137−006. Here, we investigate the origin of these ‘synchrotron threads’ to understand if they may be confined magnetically and could arise due to shocks associated with jet activity. Through simulation- and theory-based analysis, we find that the dynamical time (⁠ Myr) associated with the shock front closely matches the estimated synchrotron age (⁠ Myr) of the threads, thus making the shock origin hypothesis a favorable scenario for this particular filament.