Year: 2026
Type: article
Abstract: Context. We present simulations of a massive young star cluster using the codes Nbody6++GPU and MOCCA. The cluster is initially more compact than previously published models. It contains one million stars and has a total mass of 5.86 × 105 M⊙ and a half-mass radius of 0.1 pc. Aims. We analyzed the formation and growth of a very massive star (VMS) through successive stellar collisions and investigated the subsequent formation of an intermediate-mass black hole (IMBH) in the core of a dense star cluster. Methods. We used direct N-body and Monte Carlo simulations that incorporated updated stellar evolution prescriptions for single and binary stellar evolution (SSE and BSE) tailored to massive stars and VMSs. These include revised treatments of stellar radii, rejuvenation, and mass loss during collisions. While the prescriptions represent reasonable extrapolations into the VMS regime, the internal structure and thermal state of VMSs that formed through stellar collisions remain uncertain, and future work may require further refinement. Results. Runaway stellar collisions in the cluster core produce a VMS that exceeds 5 × 104 M⊙ within 5 Myr that subsequently collapses into an IMBH. We stress that further work on stellar astrophysics is needed, particularly in the context of VMS formation. The VMS formation currently represents strong uncertainties. Conclusions. Our model suggests that dense stellar environments may enable the formation of VMSs and massive black hole seeds through runaway stellar collisions. These results provide a potential pathway for early black hole growth in star clusters and offer a theoretical context for interpreting recent observations with the James Webb Space Telescope of young compact clusters at high redshift.
Authors: Marcelo C. Vergara, Abbas Askar, Albrecht W. H. Kamlah, Rainer Spurzem, Francesco Flammini Dotti, Dominik R. G. Schleicher, Manuel Arca Sedda, Arkadiusz Hypki, Mirek Giersz, Jarrod Hurley, Peter Berczik, Andres Escala, Nils Hoyer, Nadine Neumayer, Xiaoying Pang, Ataru Tanikawa, Renyue Cen, Thorsten Naab
Institutions: Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Max Planck Institute for Astronomy, University of Concepción, Sapienza University of Rome, Adam Mickiewicz University in Poznań, ARC Centre of Excellence for Gravitational Wave Discovery, National Academy of Sciences of Ukraine, Main Astronomical Observatory, University of Chile, Shanghai Normal University, Xi’an Jiaotong-Liverpool University, The University of Tokyo, Fukui Prefectural University, Zhejiang University, Max Planck Institute for Astrophysics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, New York University Abu Dhabi, International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, European Commission, Deutscher Akademischer Austauschdienst, Deutsche Forschungsgemeinschaft, Universität Heidelberg, National Natural Science Foundation of China, Centro de Astrofísica y Tecnologías Afines, International Max Planck Research School for Advanced Methods in Process and Systems Engineering, Fondation Merac, Tamkeen, Agencia Nacional de Investigación y Desarrollo, Gauss Centre for Supercomputing, Japan Society for the Promotion of Science, National Key Research and Development Program of China, National Astronomical Observatories, Chinese Academy of Sciences, Kavli Institute for Theoretical Physics, University of California, Santa Barbara
Awards: Postdoctoral Fellowships in Poland to Boost International Mobility and Skills Training, G1750626284, G1813321918, G1820675529, G1897041155, G2271482297, G2329447088, G3183642665, G3398237449, G380733860, G384842228, Toward understanding of merging binary black hole formation in all the stellar systems from galactic fields to dense stellar clusters, G4066435496, G4209578648, G4246495971, EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens, G4452337565, G4689434848, 3-dimensional fluid simulation for the origin of hyper-velocity white dwarfs and type Ia supernovae, G5109189900, G5156733829, Gravitational waves from crowded environments: simulating intermediate-mass black hole formation and evolution with supercomputers., G5834573078, G5857371469, G595377943, ECLIPSING TIME VARIATIONS IN POST-COMMON-ENVELOPE BINARIES PLANETARY HYPOTHESIS VS. MAGNETIC ACTIVITY, Kavli Institute for Theoretical Physics, G7222951290, G7350863329, G7474525914, THE NEXT STEP FOR ASTROPHYSICAL SUPERCOMPUTING IN CHILE A POWERFUL GPU-SERVER FOR FLUID AND STELLAR DYNAMICS, G8382749824, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA)
OpenAlex ID: W7115900392
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