{
  "abstract": "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 ($4\\times 10^3 \\lesssim \\Sigma _\\mathrm{h} \\lesssim 4\\times 10^6 \\, \\mathrm{M_\\odot \\, pc^{-2}}$) and metallicities $(0.01 \\lesssim Z \\lesssim 1.0 \\, \\mathrm{Z_\\odot })$. Our sample of isolated (>1400) and hierarchical (30) simulations of young, massive star clusters with up to $N=1.8\\times 10^6$ stars includes collisional stellar dynamics, stellar evolution, and post-Newtonian equations of motion for black holes using the bifrost code. High stellar wind rates suppress IMBH formation at high metallicities ($Z \\gtrsim 0.2 \\, \\mathrm{Z_\\odot }$), and low collision rates prevent their formation at low densities ($\\Sigma _\\mathrm{h}\\lesssim 3\\times 10^4 \\, \\mathrm{M_\\odot \\, pc^{-2}}$). The assumptions about stellar wind loss rates strongly affect the maximum final IMBH masses ($M_\\bullet \\sim 6000 \\, \\mathrm{M_\\odot }$ versus $M_\\bullet \\sim 25\\,000 \\, \\mathrm{M_\\odot }$). The total stellar mass loss from collisions and collisionally boosted winds before $t=3$ Myr can together reach up to 5–10 per cent of the final cluster mass. We present fitting formulae for IMBH masses as a function of host star cluster $\\Sigma _\\mathrm{h}$ and Z which can be used to seed SMBHs in high-resolution cosmological hydrodynamical simulations and in semi-analytic models for galaxy formation. Our results favour IMBH formation in dense low-metallicity environments similar to $z\\sim 10$ JWST (James Webb Space Telescope) proto-globular clusters. IMBH formation is suppressed in the high-metallicity and low-density conditions of the local Universe.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Astronomy, University of Cambridge , Madingley Road, Cambridge CB3 0HA ,",
    "Kavli Institute for Cosmology, Cambridge (KICC), University of Cambridge , Madingley Road, Cambridge CB3 0HA ,",
    "Max-Planck-Institut für Astrophysik , Karl-Schwarzschild-Str 1, D-85748 Garching ,",
    "Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut , Mönchhofstr 12-14, D-69120 Heidelberg ,",
    "Max Planck Computing and Data Facility (MPCDF) , D-85748 Garching ,",
    "European Southern Observatory , Karl-Schwarzschild-Str 2, D-85748 Garching ,",
    "University of Helsinki Department of Physics, , PO Box 64, Gustaf Hällströmin katu 2, FI-00014 Helsinki ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Antti Rantala",
      "orcid": "0000-0001-8789-2571"
    },
    {
      "affs": [
        2
      ],
      "name": "Thorsten Naab",
      "orcid": "0000-0002-7314-2558"
    },
    {
      "affs": [
        2,
        3
      ],
      "name": "Natalia Lahén",
      "orcid": "0000-0003-2166-1935"
    },
    {
      "affs": [
        4
      ],
      "name": "Klaus Reuter",
      "orcid": "0000-0001-6869-7877"
    },
    {
      "affs": [
        4
      ],
      "name": "Markus Rampp",
      "orcid": "0000-0001-8177-8698"
    },
    {
      "affs": [
        5
      ],
      "name": "Martyna Chruślińska",
      "orcid": "0000-0002-8901-6994"
    },
    {
      "affs": [
        6
      ],
      "name": "B. Reinoso",
      "orcid": "0000-0002-1991-4465"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/46yp8r86kagt9.bib",
  "cited_by": 25,
  "doi": "10.1093/mnras/stag986",
  "fulltext_url": null,
  "id": "46yp8r86kagt9",
  "issns": [
    "0035-8711",
    "1365-2966",
    "1365-8711"
  ],
  "landing_url": "https://doi.org/10.1093/mnras/stag986",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7162572181",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-05-27",
  "publisher": "Oxford University Press",
  "ris": "https://research.draconitic.com/paper/46yp8r86kagt9.ris",
  "sources": [
    {
      "first_seen": "2026-11-07T13:20:45Z",
      "native_id": "W7162572181",
      "source": "openalex",
      "url": "https://doi.org/10.1093/mnras/stag986"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Galaxies: Formation, Evolution, Phenomena",
      "subfield": "galaxies"
    }
  ],
  "title": "FROST-CLUSTERS – III. Metallicity-dependent intermediate-mass black hole formation by runaway collisions in dense star clusters",
  "title_text": "FROST-CLUSTERS – III. Metallicity-dependent intermediate-mass black hole formation by runaway collisions in dense star clusters",
  "type": "peer-reviewed",
  "updated_at": "2026-11-09T13:21:02Z",
  "url": "https://research.draconitic.com/paper/46yp8r86kagt9",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}