The alignment of galaxy clusters

The large-scale alignment of galaxy clusters found by Binggeli was tested on the basis of the complete sample of clusters which belong to the Bahcall and Soneira superclusters using various determinations of the clusters' position angle. For small separations, clusters do tend to point toward their neighbours, but the effect is weak. Correlation of anisotropy with cluster separation is also weak. Comparison of the observational data with theoretical models shows that for small separations the alignment is similar to that predicted in the adiabatic scenario, while for greater distances between clusters to that in the isothermal one.