2012ApJ...747....7G

In the 1975 Hawley and Peebles proposed the use of three statistical tests for investigations of galaxy orientations in the large structures. Nowadays, it is considered as the standard method of searching for galactic alignments. In the present paper we analyzed the tests in detail and proposed a few improvements. Based on the improvements, a new method of analysis of the alignment of galaxies in clusters is proposed. The power of this method is demonstrated on the sample of 247 Abell clusters with at least 100 objects in each. The distributions of the position angles for galaxies in each cluster are analyzed using statistical tests: χ², Fourier, autocorrelation, and Kolmogorov test. The mean value of analyzed statistics is compared with theoretical predictions as well as with results obtained from numerical simulations. We performed 1000 simulations of 247 fictitious clusters, each with the numbers of galaxies the same as in the real clusters. We found that orientations of galaxies in analyzed clusters are not random, i.e., that there exists an alignment of galaxies in rich Abell galaxy clusters.