Intermediate mass black hole formation in compact young massive star clusters

2020/08/21 by Francesco Paolo Rizzuto, Thorsten Naab, Rainer Spurzem +9 · 1 citation
Physics and Astronomy · #Accretion (finance) #Astrophysical Phenomena and Observations #Astrophysics #Binary number #Black hole (networking) #Cluster (spacecraft) #Compact star #Gamma-ray bursts and supernovae #Mass segregation #Physics #Pulsars and Gravitational Waves Research #Star (game theory) #Star cluster #Star formation #Stars #Stellar mass #astro-ph.GA

paper · pdf · doi:10.1093/mnras/staa3634

Submitted

arxiv created 2020/08/21 · openalex publication_date 2020/11/20 · arxiv updated 2020/12/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

ABSTRACT Young dense massive star clusters are promising environments 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 models of compact ∼ 7 × 10⁴ M_\odot star clusters with half-mass radii Rh ≲ 1 pc, central densities ρ _core \gtrsim 10⁵ M_\odot pc^-3, and resolved stellar populations with 10 per cent primordial binaries. Very massive stars (VMSs) up to ∼ 400 M_\odot grow rapidly by binary exchange and three-body scattering with stars in hard binaries. Assuming that in VMS–stellar black hole (BH) collisions all stellar material is accreted on to the BH, IMBHs with masses up to M_BH ∼ 350 M_\odot can form on time-scales of ≲15 Myr, as qualitatively predicted from Monte Carlo mocca simulations. One model forms an IMBH of 140 \mathrmM_\odot by three BH mergers with masses of 17:28, 25:45, and 68:70 \mathrmM_\odot within ∼90 Myr. Despite the stochastic nature of the process, formation efficiencies are higher in more compact clusters. Lower accretion fractions of 0.5 also result in IMBH formation. The process might fail for values as low as 0.1. The IMBHs can merge with stellar mass BHs in intermediate mass ratio inspiral events on a 100 Myr time-scale. With 105 stars, 10 per cent binaries, stellar evolution, all relevant dynamical processes, and 300 Myr simulation time, our large suite of 80 simulations indicate another rapid IMBH formation channel in young and compact massive star clusters.

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