A new Monte Carlo code for star cluster simulations: II. Central black hole and stellar collisions

TL;DR

This paper introduces an advanced Monte Carlo simulation code for star cluster evolution, incorporating a central black hole, stellar collisions, and stellar evolution, enabling efficient long-term modeling of dense galactic nuclei.

Contribution

The paper presents a novel Monte Carlo code that integrates black hole growth, stellar collisions, and stellar evolution for realistic, long-term galactic nucleus simulations.

Findings

Code successfully simulates million-particle systems over a Hubble time.

Realistic modeling of stellar collisions using over 10,000 SPH simulations.

The code runs efficiently on standard personal computers.

Abstract

We have recently written a new code to simulate the long term evolution of spherical clusters of stars. It is based on the pioneering Monte Carlo scheme proposed by Henon in the 70's. Our code has been devised in the specific goal to treat dense galactic nuclei. After having described how we treat relaxation in a first paper, we go on and include further physical ingredients that are mostly pertinent to galactic nuclei, namely the presence of a central (growing) black hole (BH) and collisions between MS stars. Stars that venture too close to the BH are destroyed by the tidal field. This process is a channel to feed the BH and a way to produce accretion flares. Collisions between stars have often been proposed as another mechanism to drive stellar matter into the central BH. To get the best handle on the role of this process in galactic nuclei, we include it with unpreceded realism through the use of a set of more than 10000 collision simulations carried out with a SPH (Smoothed Particle Hydrodynamics) code. Stellar evolution has also been introduced in a simple way, similar to what has been done in previous dynamical simulations of galactic nuclei. To ensure that this physics is correctly simulated, we realized a variety of tests whose results are reported here. This unique code, featuring most important physical processes, allows million particle simulations, spanning a Hubble time, in a few CPU days on standard personal computers and provides a wealth of data only rivalized by N-body simulations.