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Related papers: FROST-CLUSTERS -- II. Massive stars, binaries and …

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Observations and high-resolution hydrodynamical simulations indicate that massive star clusters assemble hierarchically from sub-clusters with a universal power-law cluster mass function. We study the consequences of such assembly for the…

Astrophysics of Galaxies · Physics 2024-06-05 Antti Rantala , Thorsten Naab , Natalia Lahén

We explore the formation of intermediate mass black holes (IMBHs), potential seeds for supermassive black holes (SMBHs), via runaway stellar collisions for a wide range of star cluster (surface) densities ($4\times10^3 M_\odot$ pc$^{-2}…

Motivated by JWST observations of dense, clumpy and clustered high redshift star formation, we simulate the hierarchical assembly of nine $M_{\mathrm{cl}}=10^6 M_\odot$ star clusters using the BIFROST N-body code. Our low metallicity models…

Astrophysics of Galaxies · Physics 2025-09-08 Antti Rantala , Thorsten Naab

Star clusters can interact and merge in galactic discs, halos, or centers. We present direct N-body simulations of binary mergers of star clusters with $M_{\star} = 2.7 \times 10^4 \: \mathrm{M_{\odot}}$ each, using the N-body code BIFROST…

Astrophysics of Galaxies · Physics 2025-03-18 Lazaros Souvaitzis , Antti Rantala , Thorsten Naab

Very massive stars (VMSs) formed via a sequence of stellar collisions in dense star clusters have been proposed as the progenitors of massive black hole seeds. VMSs could indeed collapse to form intermediate-mass black holes (IMBHs), which…

Astrophysics of Galaxies · Physics 2024-04-19 Elena González Prieto , Newlin C. Weatherford , Giacomo Fragione , Kyle Kremer , Frederic A. Rasio

Dense star clusters are promising nurseries for the formation and growth of intermediate-mass black holes (IMBHs; $\sim 10^2-10^5\,\mathrm{M}_{\odot}$), with increasing observational evidence pointing to their presence in massive star…

Astrophysics of Galaxies · Physics 2025-10-07 Abbas Askar , Marcelo C. Vergara , Sohaib Ali

We study the stellar dynamics of the first star clusters after intermediate-mass black holes (IMBHs) are formed via runaway stellar collisions. We use the outputs of cosmological simulations of Sakurai et al. (2017) to follow the star…

Astrophysics of Galaxies · Physics 2019-01-31 Yuya Sakurai , Naoki Yoshida , Michiko S. Fujii

Young dense massive star clusters are a promising environment for the formation of intermediate mass black holes (IMBHs) through collisions. We present a set of 80 simulations carried out with Nbody6++GPU of 10 initial conditions for…

We investigate the formation of intermediate mass black holes (IMBHs) through hierarchical mergers of stellar origin black holes (BHs), as well as BH mergers formed dynamically in nuclear star clusters. Using a semi-analytical approach…

High Energy Astrophysical Phenomena · Physics 2023-10-04 Debatri Chattopadhyay , Jakob Stegmann , Fabio Antonini , Jordan Barber , Isobel M. Romero-Shaw

Supermassive black holes (SMBHs) are found in most galactic nuclei. A significant fraction of these nuclei also contain a nuclear stellar cluster (NSC) surrounding the SMBH. In this paper, we consider the idea that the NSC forms first, from…

Astrophysics of Galaxies · Physics 2021-01-27 Abbas Askar , Melvyn B. Davies , Ross P. Church

The observational dearth of black holes (BHs) with masses between $\sim$100 and 100,000 $M_\odot$ raises questions about the nature of intermediate-mass black holes (IMBHs). Proposed formation channels for IMBHs include runaway stellar…

Astrophysics of Galaxies · Physics 2026-04-08 Lavinia Paiella , Manuel Arca Sedda , Benedetta Mestichelli , Cristiano Ugolini

In a star cluster with a sufficiently large escape velocity, black holes (BHs) that are produced by BH mergers can be retained, dynamically form new BH binaries, and merge again. This process can repeat several times and lead to significant…

High Energy Astrophysical Phenomena · Physics 2019-07-17 Fabio Antonini , Mark Gieles , Alessia Gualandris

The processes that govern the formation of intermediate-mass black holes (IMBHs) in dense stellar clusters are still unclear. Here, we discuss the role of stellar mergers, star-BH interactions and accretion, as well as BH binary (BBH)…

In many galactic nuclei, a nuclear stellar cluster (NSC) co-exists with a supermassive black hole (SMBH). In this work, we explore the idea that the NSC forms before the SMBH through the merger of several stellar clusters that may contain…

Astrophysics of Galaxies · Physics 2024-02-05 Abbas Askar , Melvyn B. Davies , Ross P. Church

We study the formation of massive black holes in the first star clusters. We first locate star-forming gas clouds in proto-galactic haloes of $\gtrsim \!10^7\,{\rm M}_{\odot}$ in cosmological hydrodynamics simulations and use them to…

Astrophysics of Galaxies · Physics 2017-08-15 Yuya Sakurai , Naoki Yoshida , Michiko S. Fujii , Shingo Hirano

We have followed the evolution of multi-mass star clusters containing massive central black holes through collisional N-body simulations done on GRAPE6. Each cluster is composed of between 16,384 to 131,072 stars together with a black hole…

Astrophysics · Physics 2009-11-10 Holger Baumgardt , Junichiro Makino , Toshikazu Ebisuzaki

Current theoretical models predict a mass gap with a dearth of stellar black holes (BHs) between roughly $50\,M_\odot$ and $100\,M_\odot$, while, above the range accessible through massive star evolution, intermediate-mass BHs (IMBHs) still…

Astrophysics of Galaxies · Physics 2022-03-30 Giacomo Fragione , Bence Kocsis , Frederic A. Rasio , Joseph Silk

Numerical simulations have established that star clusters with densities comparable to the high redshift ($z>6$-$10$) James Webb Space Telescope (JWST) proto globular clusters may build up extremely massive (EMSs; $m_\mathrm{\star}>1000…

Astrophysics of Galaxies · Physics 2026-04-28 Antti Rantala

Observations suggest that star clusters often form in binaries or larger bound groups. Therefore, mergers between two clusters are likely to occur. If these clusters both harbor an intermediate-mass black hole (IMBH; 10^{2-4} Msun) in their…

Astrophysics · Physics 2009-11-11 Pau Amaro-Seoane , Marc Freitag

Context. We present simulations of a massive young star cluster using \textsc{Nbody6++GPU} and \textsc{MOCCA}. The cluster is initially more compact than previously published models, with one million stars, a total mass of $5.86 \times…

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