Radio halo powers plotted against cluster mass proxies. Left: distribution of clusters in the mass (M₅₀₀) 150 MHz radio power (P_150 MHz) plane. The solid black line displays the BCES orthogonal fit (candidate halos were excluded). The shaded region shows the 3σ (99.7% confidence) region of the fit. The blue line is the BCES orthogonal fit from Cassano et al. (2013) scaled with a spectral index of −1.2. Right: distribution of clusters in the Y₅₀₀ 150 MHz radio power plane. The plotted symbols and lines represent the same data sets as in the left panel.