Median X-ray surface brightness of the extended detected (red) and undetected (blue) sources in the 0.5 − 2.0 keV for four different logarithmic halo mass bins (i.e. log(M₂₀₀/M_⊙) reported at the top of each panel). In the lower left of each panel, we report the number of detected and undetected in the mass bin. The shaded bands illustrate the 16^th − 84^th percentiles from the intrinsic distribution.