Left: regions where radio and X-ray data are extracted. Middle: correlation between radio and X-ray SB. Right: scatter plot of the radio spectral index and X-ray SB. The solid and dashed (black) lines show the best-fit results from the MCMC runs. The thin (blue and green) lines are the fitting results of some individual MCMC runs. In both plots, the 2σ upper limits are shown with the downward- and leftward-pointing arrows.