N-body simulations of galaxy bars generated by satellite collisions: effects of the impact geometry

TL;DR

This study uses N-body simulations to explore how satellite galaxy collisions can induce bar formation in disk galaxies, highlighting the impact of collision parameters and intruder mass.

Contribution

It provides a detailed analysis of how various collision parameters influence bar formation, emphasizing the role of satellite impacts in galaxy evolution.

Findings

Moderate collision velocity favors bar formation.

Large inclination angles promote bar development.

Intruder mass > 3×10^9 M_sun is necessary for effective bar formation.

Abstract

Bars, a common and important structure in disk galaxies, can be induced by galaxy interactions. Although there have been some studies on bar formation in flybys or collisions, the vast parameter space still leaves many scenarios that require further investigation. Here, we focus on the role of collisions caused by small galaxies (denoted as intruders), referred to as satellite collisions, in bar formation for MW/M31-like galaxies (denoted as target galaxies). Multiple sets of simulations with varying intruder initial velocities, inclination angles, collision positions, and intruder masses were run to study the dependence of this mechanism on these parameters. Our simulations show that bar formation favors moderate collision velocity, large inclination angle, off-center collision position, and large intruder mass. However, the bar's pattern speed and length are insensitive to these parameters, as the intruder's mass is relatively small compared to that of the target galaxy itself. Moreover, based on our tests, the intruder mass should be more than $\sim 3\times10^{9}$ ${\rm M}_{\odot}$ in order for this bar formation mechanism to operate effectively in MW/M31-like galaxies. Our work suggests the possibility that satellite collisions may have contributed, to some extent, to the bar formation in the Milky Way or M31.