Direct N-body simulation of the Galactic centre

TL;DR

This study uses a high-resolution N-body simulation to analyze the Milky Way's nuclear star cluster, revealing stellar distribution evolution, tidal disruption rates, gravitational wave sources, and binary star dynamics near the supermassive black hole.

Contribution

It provides the first detailed direct N-body simulation of the Galactic center with one million particles, offering new insights into stellar dynamics, black hole interactions, and binary evolution.

Findings

Black hole distribution follows Bahcall-Wolf slope -1.75

Tidal disruption rate estimated at 4e-6 per year

Approximately 270 gravitational wave sources per Gyr

Abstract

We study the dynamics and evolution of the Milky Way nuclear star cluster performing a high resolution direct one-million-body simulation. Focusing on the interactions between such stellar system and the central supermassive black hole, we find that different stellar components adapt their overall distribution differently. After 5 Gyr, stellar mass black holes are characterized by a spatial distribution with power-slope $-1.75$, fully consistent with the prediction of Bahcall-Wolf pioneering work. Using the vast amount of data available, we infer the rate for tidal disruption events, being $4 \times 10^{-6}$ per yr, and estimate the number of objects that emit gravitational waves during the phases preceding the accretion onto the super-massive black hole, $\sim 270$ per Gyr. We show that some of these sources could form extreme mass-ratio inspirals. We follow the evolution of binary stars population, showing that the initial binary fraction of $5\%$ drops down to $2.5\%$ inside the inner parsec. Also, we explored the possible formation of binary systems containing a compact object, discussing the implications for millisecond pulsars formation and the development of Ia Supernovae.