The dragon-II simulations - II. Formation mechanisms, mass, and spin of intermediate-mass black holes in star clusters with up to 1 million stars

• Verfasst von: Arca Sedda, Manuel [VerfasserIn]
• Verfasst von: Kamlah, Albrecht [VerfasserIn]
• Verfasst von: Spurzem, Rainer [VerfasserIn]
• Verfasst von: Rizzuto, Francesco Paolo [VerfasserIn]
• Verfasst von: Naab, Thorsten [VerfasserIn]
• Verfasst von: Giersz, Mirek [VerfasserIn]
• Verfasst von: Berczik, Peter [VerfasserIn]
• Titel: The dragon-II simulations - II. Formation mechanisms, mass, and spin of intermediate-mass black holes in star clusters with up to 1 million stars
• Verf.angabe: Manuel Arca Sedda, Albrecht W.H. Kamlah, Rainer Spurzem, Francesco Paolo Rizzuto, Thorsten Naab, Mirek Giersz and Peter Berczik
• E-Jahr: 2023
• Jahr: November 2023
• Umfang: 14 S.
• Illustrationen: Illustrationen
• Fussnoten: Vorab online veröffentlicht: 25. September 2023 ; Gesehen am 26.01.2024
• Titel Quelle: Enthalten in: Royal Astronomical SocietyMonthly notices of the Royal Astronomical Society
• Ort Quelle: Oxford : Oxford Univ. Press, 1827
• Jahr Quelle: 2023
• Band/Heft Quelle: 526(2023), 1, Seite 429-442
• ISSN Quelle: 1365-2966
• DOI: doi:10.1093/mnras/stad2292
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1879089319

Abstract

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) mergers in seeding and growing IMBHs in the Dragon-II simulation database, a suite of 19 direct N-body models representing dense clusters with up to 106 stars. Dragon-II IMBHs have typical masses of mIMBH = (100-380) M⊙ and relatively large spins χIMBH > 0.6. We find a link between the IMBH formation mechanism and the cluster structure. In clusters denser than 3 × 105 M⊙ pc−3, the collapse of massive star collision products represents the dominant IMBH formation process, leading to the formation of heavy IMBHs (mIMBH > 200 M⊙), possibly slowly rotating, that form over times <5 Myr and grow further via stellar accretion and mergers in just <30 Myr. BBH mergers are the dominant IMBH formation channel in less dense clusters, for which we find that the looser the cluster, the longer the formation time (10-300 Myr) and the larger the IMBH mass, although remaining within 200 M⊙. Strong dynamical scatterings and relativistic recoil efficiently eject all IMBHs in Dragon-II clusters, suggesting that IMBHs in this type of cluster are unlikely to grow beyond a few 102 M⊙.