Radio and X-ray surface brightness correlation plots for every cell from the grid used for the point-to-point analysis in the right panel of Fig. 6 for the R02 filter and uv-subtract maps. This is just one grid from the MC grid generation with 40 randomly drawn points to improve the readability of the plot. Top left panel: radio halo of A399. Top right panel: radio halo extension of A399. Lower left panel: radio halo of A401. Lower right panel: radio bridge. Error bars include the statistic and systematic uncertainties. The best linear fit with LIRA is given with a dashed black line. Only radio brightness values higher than 2σ are included.