Radial trends of the radio vs. X-ray correlation. Left: example of images (LOFAR HBA contours at 134″ are overlaid on the XMM-Newton image) and elliptical sectors used to measure the surface brightnesses; for ease of inspection, the shown images include the discrete sources, whereas these were subtracted (or masked in case of residuals) during analysis. Right: radio vs. X-ray correlation slope as a function of the radial distance from BCG1. The widths of the concentric elliptical sampling sectors depend on the beam of the radio image and the required S/N, and are reported in the legend. The global trend k(r) is sublinear, albeit with two narrow peaks.