Melnyk O. Physical properties of the sparsely populated galaxy groups in the Local Supercluster

The thesis deals with the study of physical properties of the sparsely populated galaxy groups in the Local Supercluster. 3-D Voronoi's tessellation method for identifying groups of galaxies was developed. It includes the original way of overscaling distances to galaxies with the purpose to avoid the selection effects as concerns with galaxies of a weak luminosity. Various regularities of the physical properties of galaxy groups are revealed. The dependence between morphological content, population, activity and color indices of interacting galaxies in groups and triplets was revealed, which characterizes the evolutionary status of group and can be evidence in favor of the model of hierarchical merging. It was found that individual mass-to-luminosity ratio of galaxies in triplets does not depend from the sample and does not differ from the corresponding values of isolated galaxies M25/L ~ 5 Мs/Ls . Ratio of triplet's virial mass to the sum of individual mass of its components depends on sample and isequal to 7 - 40. It is shown that physical properties of groups depend exactly on initial galaxy catalog and method of galaxy identification into groups. The obtained results argue in favor of the model that a hidden mass is concentrated in the halo of individual galaxies, which is a part of triple system, rather than the model of a hidden mass concentrated in the triplet's volume, except the compact galaxy groups.