Diagram of the X-ray morphological indicators based on Chandra observations for the galaxy clusters, the emission centroid shift, w, and the concentration parameter, c, of the mass-selected cluster sample in Cuciti et al. (2015) and Cassano et al. (2016). Red squares indicate the sources of our sample. Following Cassano et al. (2010), we adopted the values w ≤ 0.012 and c ≥ 0.2 as an indication of the distinction between merging/non-merging clusters. Merging clusters lie in the bottom right region of the plot, whilst non-merging clusters in the top left region.