Exploring the physics behind the observed magnetic filaments in large scale radio galaxies

Abstract

Recent low-frequency MeerKAT observations of radio galaxies have revealed an unexpected population of thin, highly collimated synchrotron threads, whose numbers continue to grow with increasing survey depth and sensitivity. These intricate structures display a remarkable diversity of morphologies -- appearing as narrow filaments linking jets and lobes, as well as ring- or ribbon-like features embedded within the jets and radio lobes. Despite their ubiquity, the physical origin and stability of these collimated synchrotron threads remain poorly understood. Proposed mechanisms include shock compression and interactions with the magneto-ionic intracluster medium, magnetic flux tube formation, and reconnection-driven magnetic filaments. In this work, we investigate the formation and evolution of such magnetic filaments using three-dimensional, two-temperature general relativistic magnetohydrodynamic (GRMHD) simulations of realistically launched jets from supermassive black holes. From these simulations, we compute synthetic synchrotron emission maps and polarisation signatures, allowing us to predict the observable characteristics including morphology, brightness profiles, and polarisation patterns. Finally, we assess the detectability and diagnostic potential of these signatures with the Square Kilometre Array Observatory (SKAO), outlining how upcoming SKA observations can distinguish between competing physical models and illuminate the magnetic origin of the collimated synchrotron threads revealed by MeerKAT observations.