A New Method of Investigation of the Orientation of Galaxies in Clusters in the Absence of Information on Their Morphological Types

Abstract

The analysis of the orientation of galaxies is one of the most widely used tools in the fields of extragalactic astronomy and cosmology, enabling the verification of structure formation scenarios in the universe. It is based on the statistical analysis of the distribution of angles, giving the spatial orientation of galaxies in space. In order to obtain the correct analysis results, one is obliged to take into account the Holmberg effect and the fact that galaxies are oblate spheroids, with the real axis ratio depending on the morphological type. However, most of the astronomical data available today do not contain information about the morphological types of galaxies. The analysis of sufficiently numerous observational data allows one to calculate the estimated frequency of the occurrence of given morphological types used in the proposed method. As a part of this, on the basis of these frequencies, simulations were performed, which enabled us to recognize new angle distributions used in orientation studies. These distributions already contain information on the frequency of the appearance of galaxies of particular morphological types in clusters, allowing for more accurate results of the statistical tests carried out during the analysis. The method is an extension of results developed in in our previous investigations.