Evolution of Nuclear Star Cluster in Dwarf Galaxy through Mergers and In-Situ Star Formation

TL;DR

This paper presents advanced simulations of nuclear star cluster evolution in dwarf galaxies, exploring how mergers and in-situ star formation contribute to their growth and structure.

Contribution

The study introduces a novel simulation framework combining hydrodynamics and N-body physics to investigate NSC evolution with multiple physical processes included.

Findings

Both mergers and in-situ star formation significantly influence NSC growth.

Mergers can disrupt dense gas, suppressing in-situ star formation.

Limitations include lack of detailed star physics and resolution constraints.

Abstract

Nuclear Star Clusters (NSCs) are dense stellar systems located at the centers of galaxies. Employing Enzo-Abyss, which integrates hydrodynamics with a direct N-body solver, we introduce a simulation capable of resolving the evolution of NSCs within a live galaxy. This includes live dark matter, gaseous dynamics, star formation and feedback, collisional dynamics for star clusters. The evolution of NSCs is typically shaped by two main processes: mergers of star clusters and in-situ star formation. Our simulation enables investigation of the contributions of these mechanisms to the growth of NSCs. This work focuses on the impact of stellar physics and gas content on the growth of NSCs within a dwarf galaxy. To this end, we carry out four simulations, a fiducial simulation, one without supernova feedback, one with low star formation efficiency, and one with higher galactic gas content. This study shows a likelihood that both mergers and in-situ star formation contribute to NSC evolution comparably. In addition, mergers result in disruption of dense gas clumps within star clusters, indicating that in-situ star formation is suppressed when mergers occur. However, the limitations -- such as the lack of individual star physics and limited spatial/particle mass resolution -- hinder drawing a definite conclusion. Nevertheless, with further development, our simulations will serve as a cornerstone that untangles the complex interplay between mergers and in-situ star formation in shaping the structure and mass of NSCs, thereby providing insights into their formation and evolution.