Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations

We recently developed a Monte Carlo method ( GNC ) that can simulate the dynamical evolution of a nuclear star cluster (NSC) with a massive black hole (MBH), where the two-body relaxations can be solved by the Fokker–Planck equations in energy and angular momentum space. Here we make a major update...

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Main Authors: Fupeng Zhang, Pau Amaro Seoane
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adaa7a
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author Fupeng Zhang
Pau Amaro Seoane
author_facet Fupeng Zhang
Pau Amaro Seoane
author_sort Fupeng Zhang
collection DOAJ
description We recently developed a Monte Carlo method ( GNC ) that can simulate the dynamical evolution of a nuclear star cluster (NSC) with a massive black hole (MBH), where the two-body relaxations can be solved by the Fokker–Planck equations in energy and angular momentum space. Here we make a major update of GNC by integrating stellar potential and adiabatic invariant theory, so that we can study the self-consistent dynamics of NSCs with increasing mass of the MBH. We perform tests of the self-adaptation of cluster density due to MBH mass growth and Plummer core collapse, both finding consistent results with previous studies, the latter having a core collapse time of ∼17 t _rh by GNC , where t _rh is the time of half-mass relaxation. We use GNC to study the cosmological evolution of the properties of NSCs and the mass of MBHs assuming that the mass growth of the MBH is due to loss-cone accretion of stars (e.g., tidal disruption of stars) and stellar black holes, and we compare the simulation results with the observations of NSCs in the Milky Way or nearby galaxies. It is possible for such a scenario to produce MBHs with mass 10 ^5 –10 ^7 M _⊙ for NSCs with stellar mass of 10 ^6 –10 ^9 M _⊙ . In the Milky Way's NSC, to grow an MBH up to 4 × 10 ^6 M _⊙ , its size needs to be ∼1.7 times more compact in early Universe than the current value. MBHs with current masses >6 × 10 ^7 M _⊙ seem difficult to explain by loss-cone accretion alone, and thus they may require other additional accretion channels, such as gas accretion.
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spelling doaj-art-35f5628c256549179d1d4e7a56d1fa592025-08-20T03:17:36ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01980221010.3847/1538-4357/adaa7aSelf-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical SimulationsFupeng Zhang0https://orcid.org/0000-0002-0403-9522Pau Amaro Seoane1School of Physics and Materials Science , Guangzhou University, Guangzhou 510006, People’s Republic of China ; zhangfupeng@gzhu.edu.cn; Key Laboratory for Astronomical Observation and Technology of Guangzhou , Guangzhou 510006​, People’s Republic of China; Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province , Guangzhou 510006, People’s Republic of ChinaInstitute of Multidisciplinary Mathematics, Universitat Politècnica de València , Spain; Max-Planck-Institute for Extraterrestrial Physics , Garching, Germany; The Higgs Centre for Theoretical Physics, University of Edinburgh , UKWe recently developed a Monte Carlo method ( GNC ) that can simulate the dynamical evolution of a nuclear star cluster (NSC) with a massive black hole (MBH), where the two-body relaxations can be solved by the Fokker–Planck equations in energy and angular momentum space. Here we make a major update of GNC by integrating stellar potential and adiabatic invariant theory, so that we can study the self-consistent dynamics of NSCs with increasing mass of the MBH. We perform tests of the self-adaptation of cluster density due to MBH mass growth and Plummer core collapse, both finding consistent results with previous studies, the latter having a core collapse time of ∼17 t _rh by GNC , where t _rh is the time of half-mass relaxation. We use GNC to study the cosmological evolution of the properties of NSCs and the mass of MBHs assuming that the mass growth of the MBH is due to loss-cone accretion of stars (e.g., tidal disruption of stars) and stellar black holes, and we compare the simulation results with the observations of NSCs in the Milky Way or nearby galaxies. It is possible for such a scenario to produce MBHs with mass 10 ^5 –10 ^7 M _⊙ for NSCs with stellar mass of 10 ^6 –10 ^9 M _⊙ . In the Milky Way's NSC, to grow an MBH up to 4 × 10 ^6 M _⊙ , its size needs to be ∼1.7 times more compact in early Universe than the current value. MBHs with current masses >6 × 10 ^7 M _⊙ seem difficult to explain by loss-cone accretion alone, and thus they may require other additional accretion channels, such as gas accretion.https://doi.org/10.3847/1538-4357/adaa7aStellar dynamicsSupermassive black holesGravitationGalactic centerGalaxy nucleiTidal disruption
spellingShingle Fupeng Zhang
Pau Amaro Seoane
Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations
The Astrophysical Journal
Stellar dynamics
Supermassive black holes
Gravitation
Galactic center
Galaxy nuclei
Tidal disruption
title Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations
title_full Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations
title_fullStr Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations
title_full_unstemmed Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations
title_short Self-consistent Solutions of Evolving Nuclear Star Clusters with Two-dimensional Monte Carlo Dynamical Simulations
title_sort self consistent solutions of evolving nuclear star clusters with two dimensional monte carlo dynamical simulations
topic Stellar dynamics
Supermassive black holes
Gravitation
Galactic center
Galaxy nuclei
Tidal disruption
url https://doi.org/10.3847/1538-4357/adaa7a
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