Substructures in Abell clusters of galaxies

Aims. We present the results of substructure detection on a large sample of Abell clusters. Methods. We apply the wavelet transform to positions of galaxies in 183 Abell clusters. The significance of the substructuring detected was determined using Monte Carlo simulations on sets of 1000 randomly generated distributions of galaxies for each cluster and wavelet scale. Results. 62 of the investigated clusters are strongly substructured; the frequency of occurrence of substructure is 0.34. The investigated clusters were classified as unimodal, bimodal or complex systems. The clusters were divided into clusters having substructures in the field of the cluster Sf or in the core region Sc. The Kolmogorov-Smirnov test show no significant differences at the level $\alpha=0.05$ in the distribution of clusters having Sc and Sf substructures with redshift. Using a $\chi^2$ test we found no correlation between the existence of subclustering and the morphological type of galaxy clusters.