A Simulation of the Dependence of Tidal Interaction on Galaxy Type in Compact Groups

TL;DR

This study uses N-body simulations to explore how galaxy types influence tidal interactions in compact groups, revealing that elliptical galaxies dominate interactions and that groups tend to form around early type galaxies rather than through spiral mergers.

Contribution

It provides new insights into the role of galaxy morphology in interaction strength and group evolution in compact galaxy groups.

Findings

Elliptical-elliptical interactions are most significant and long-lasting.

Groups with mixed galaxy types have stronger interactions than spiral-only groups.

Spiral-only groups exhibit weak, ongoing harassment rather than mergers.

Abstract

We have investigated the role that different galaxy types have in galaxy-galaxy interactions in compact groups. N-body simulations of 6 galaxies consisting of a differing mixture of galaxy types were run to compare the relative importance of galaxy population demographic on evolution. Three different groups with differing galaxy content were tested: all spiral, a single elliptical and 50% elliptical. Tidal interaction strength and duration were recorded to assess the importance of an interaction. A group with an equal number of spiral and elliptical galaxies has some of the longest and strongest interactions with elliptical-elliptical interactions being most significant. These elliptical-elliptical interactions are not dominated by a single large event but consist of multiple interactions. Elliptical galaxies tidally interacting with spiral galaxies, have the next strongest interaction events. For the case when a group only has a single elliptical, the largest magnitude tidal interaction is an elliptical on a spiral. Spirals interact with each other through many small interactions. For a spiral only group, the interactions are the weakest compared to the other group types. These spiral interactions are not dominated by any singular event that might be expected to lead to a merger but are more of an ongoing harassment. These results suggest that within a compact group, early type galaxies will not form via merger out of an assemblage of spiral galaxies but rather that compact groups, in effect form around an early type galaxy.