A dynamical study of the frequency of merging galaxies - III. Mergers involving disk galaxies in a single crossing time or orbital period

Abstract

A study of the expected frequency of merging galaxies, involving disk systems, is conducted on the basis of the collision theory using the impulsive approximation. The results indicate that the expected frequency of such mergers is several orders of magnitude smaller than the observational values if mergers taking place in a single crossing time are considered. The expected frequency of elliptical pairs, spiral-elliptical pairs and spiral pairs in merger is of the same order of magnitude; though spiral pairs seem to have marginally more abundance as compared to the other two types. The frequency of galaxy mergers in several orbital periods will be further investigated in the continuing series of papers. © 1991 Kluwer Academic Publishers.