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SUMMARY:Hierarchical star cluster assembly boosts intermediate-mass black 
 hole formation - Antti Rantala (MPA) 
DTSTART:20240522T103000Z
DTEND:20240522T113000Z
UID:TALK215425@talks.cam.ac.uk
CONTACT:Alison Wilson
DESCRIPTION:Observations and high-resolution hydrodynamical simulations in
 dicate that massive star clusters assemble hierarchically from sub-cluster
 s with a universal power-law cluster mass function. We study the consequen
 ces of such assembly for the formation of intermediate-mass black holes (I
 MBHs) and massive black hole (MBH) seeds at low metallicities (1% of the s
 olar value) with our updated direct N-body code BIFROST in simulations up 
 to N = 2.35 million stars. The GPU-accelerated code BIFROST is based on th
 e hierarchical fourth-order forward integrator. Few-body systems are treat
 ed using secular and regularized techniques including post-Newtonian equat
 ions of motion up to order PN3.5 and gravitational-wave recoil kicks for m
 erging BHs. \nStellar evolution is provided by the fast population synthes
 is code SEVN. IMBHs with masses up to 2200 solar masses form rapidly mainl
 y via the collapse of very massive stars (VMSs) assembled through repeated
  collisions of massive stars followed by growth through tidal disruption e
 vents (TDEs) and BH mergers. Later the IMBHs form subsystems resulting in 
 gravitational-wave BH-BH\, IMBH-BH and IMBH-IMBH mergers with a 1000 solar
  mass gravitational-wave detection being the observable prediction. \nOur 
 simulations indicate that the hierarchical formation of massive star clust
 ers in metal poor environments naturally results in formation of potential
  seeds for supermassive black holes.\n
LOCATION:Martin Ryle Meeting Room\, KICC + Online
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