Fig. 9.
Comparison between richness |$\skew7\hat{N}_{\rm mem}$| and X-ray temperature TX for XXL (filled triangles) and XMM-LSS (open squares) clusters. The solid and dashed lines show the best-fitting richness–temperature relation and the range of ±1σ intrinsic scatter. The lower panel shows the residual of fitting as a function of redshift. (Color online)