Speaker
Description
We present a systematic investigation of filamentary synchrotron structures in radio galaxies, using deep 144 MHz observations from the \textit{LOFAR} Two-Metre Sky Survey (LoTSS) in combination with archival \textit{ROSAT} X-ray data. These narrow, collimated features - linking radio lobes and often aligned with jet axes -are rare, with (\sim2.2\%) of radio galaxies exhibiting such morphology among a sample of 548 cluster-associated sources. From this parent sample, 15 candidate radio galaxies were selected, of which three exhibit clearly resolved synchrotron filaments suitable for detailed X-ray and synchrotron pressure analysis. Our selection strategy targeted bright, extended sources in rich environments, revealing 15 candidates after visual inspection, with three exhibiting prominent filaments. Although we do not have direct spectral index measurements of the filaments, their morphology and analogy with similar systems suggest steep spectra ($\alpha \lesssim -1.2$), indicative of significant particle aging. Equipartition pressures in these filaments are consistently lower than the ambient thermal pressure derived from X-ray measurements. This disparity implies a role for external confinement in filament stability, aligning with theoretical predictions of thermal pressure support and toroidal magnetic field configurations. Pressure gradients with cluster-centric radius further support environmental control, with central filaments residing in denser, hotter media. We discuss filament formation scenarios, including relic AGN outflows, magnetic draping, and plasma instabilities. Our findings highlight the utility of filamentary structures as probes of intracluster magnetic field topology and AGN feedback, and demonstrate the need for high-resolution, multi-frequency studies to constrain their origin and evolution.
| Stream | Science or Engineering |
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