Evolution of Star Clusters near the Galactic Center: Fully Self-consistent N-body Simulations

TL;DR

This paper presents fully self-consistent N-body simulations of star clusters near the Galactic center, revealing faster inspiral timescales and the importance of core collapse in cluster survival, improving upon previous models.

Contribution

It introduces the Bridge code for combined galaxy and star cluster simulations, enabling more accurate modeling of their joint evolution.

Findings

Shorter inspiral timescales than traditional models

Core collapse increases cluster survival chances

Initial conditions less severe than previously thought

Abstract

We have performed fully self-consistent $N$-body simulations of star clusters near the Galactic center (GC). Such simulations have not been performed because it is difficult to perform fast and accurate simulations of such systems using conventional methods. We used the Bridge code, which integrates the parent galaxy using the tree algorithm and the star cluster using the fourth-order Hermite scheme with individual timestep. The interaction between the parent galaxy and the star cluster is calculate with the tree algorithm. Therefore, the Bridge code can handle both the orbital and internal evolutions of star clusters correctly at the same time. We investigated the evolution of star clusters using the Bridge code and compared the results with previous studies. We found that 1) the inspiral timescale of the star clusters is shorter than that obtained with "traditional" simulations, in which the orbital evolution of star clusters is calculated analytically using the dynamical friction formula and 2) the core collapse of the star cluster increases the core density and help the cluster survive. The initial conditions of star clusters is not so severe as previously suggested.