Evolution of Star Clusters near the Galactic Center: Fully Self-Consistent N-Body Simulations

• Published in: The Astrophysical journal Vol. 686; no. 2; pp. 1082 - 1093
• Main Authors: Fujii, M, Iwasawa, M, Funato, Y, Makino, J
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 20.10.2008; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Galaxies; Galaxy: kinematics and dynamics; Digital simulation; galaxies: star clusters; N body system; Stellar evolution; Numerical method; Star clusters; methods: numerical; Galaxy: center; Galaxy clusters; Kinematics; Galactic centers; Stellar dynamics
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/591483

We have performed fully self-consistent N-body simulations of star clusters near the Galactic center (GC). Such simulations have not been previously performed, because it is difficult to generate fast and accurate simulations of these systems using conventional methods. We used the Bridge code, which integrates the parent galaxy using a tree algorithm and the star cluster using a fourth-order Hermite scheme with individual time steps. The interaction between the parent galaxy and the star cluster is calculate with a tree algorithm. Therefore, the Bridge code can handle both the orbital and internal evolution of star clusters correctly at the same time. We here investigate the evolution of star clusters using the Bridge code, and compare the results with previous studies. We find 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) core collapse of the star cluster increases the core density and helps the cluster to survive. The initial conditions of star clusters are not so severe as previously suggested.