Top: LOFAR contours at 144 MHz of the mid-resolution image (panel b, Fig. 1, σ = 231 μJy beam⁻¹, and a resolution of 14″ × 5″) at the 3, 24, and 96σ levels on top of the background-subtracted, exposure-corrected Chandra image in the 0.5 − 2.0 keV band. Bottom left: GGM-processed X-ray image produced with σ = 4 and the 144 MHz emission contours on top. Bottom right: residual unsharp-masked image obtained by combining X-ray maps smoothed with 3 and 30 pixel-wide Gaussians with the 144 MHz emission contours on top. The white arrows in the bottom panels point to the spiral pattern and the cavities described in Sect. 3.1.