Remarks on the methods of investigations of alignment of galaxies

Abstract

In the 1975 Hawley and Peebles gave the proposal to use three statistical tests for investigations of the galaxies orientation in the large structures. Nowadays, it has been considered as the standard method of searching for galactic alignments. In the present paper we analyzed the tests in details and proposed a few improvements. Basing on the improvements, the 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: ${\chi }^2$, Fourier, autocorrelation and Kolmogorow 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 fictious clusters, each with numbers of galaxies the same as the real ones. 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.

APJ accepted, Some references are missing in arXive and ADS - see PDF file

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Cited by in corpus (10)

• Alignments of galaxies within cosmic filaments from SDSS DR7
• Time evolution of intrinsic alignments of galaxies
• Polarization alignments of radio quasars in JVAS/CLASS surveys
• Weak gravitational lensing of intrinsically aligned galaxies
• Non-parametric reconstruction of cosmological observables using Gaussian Processes Regression
• Investigation of the orientation of galaxies in clusters: the importance, methods and results of research
• The distribution of galaxies gravitational field stemming from their tidal interaction
• The non-Gaussian distribution of galaxies gravitational fields
• Orientation of galaxies in structures
• Preferred alignments of angular momentum vectors of galaxies in six dynamically unstable Abell clusters