The Galactic Mergers and Gravitational Unbound Populations

TL;DR

This study uses n-body simulations to analyze how different galaxy merger types produce gravitationally unbound populations, revealing that hyperbolic mergers generate more unbound matter than parabolic ones, with dark matter being more prone to unbinding.

Contribution

It provides a comparative analysis of GUP production in parabolic and hyperbolic galaxy mergers, highlighting the influence of merger dynamics and orientations.

Findings

Hyperbolic mergers produce about twice as many GUP as parabolic mergers.

Less than 1% of stellar mass becomes luminous GUP in head-on collisions.

8-14% of dark matter becomes dark GUP in such mergers.

Abstract

Motivated by the observations on the intra-cluster light (ICL) and inter-galactic stellar populations, n-body simulations are used to model the galactic merging events as a goal to investigate the production and distribution of gravitational unbound populations (GUPs). Both the parabolic and hyperbolic mergers are considered and each category includes six models with different relative orientations between two galaxies. Our results show that there are more (about a factor of two) GUP after a hyperbolic merging event than after a parabolic one. In general, depending on the relative orientation and also the relative velocity of the two galaxies in a merging pair, a head-on collision of a galaxy pair would only make a tiny fraction (less than one percent) of the initial stellar mass become luminous GUP but a considerable fraction (eight to fourteen percent) of the dark matter become dark GUP.