Identifying Globular Clusters Hosting Large Numbers of Black Holes

Project: Research project

Project Details


The detection by LIGO of gravitational waves emitted by merging black holes (BH) has generated widespread interest in the astrophysics of binary BH (BBH) formation. Discoveries of candidate BH X-ray binaries in Galactic and extragalactic globular clusters (GC) via X-ray and radio surveys indicate the possible existence of hundreds of BHs bound to GCs. Current theoretical models also suggest that GCs are efficient factories of BBHs. A large population of BHs can dramatically alter the global dynamical evolution of the host GC. Consequently, the observable GC properties, extensively studied and catalogued using HST, are also affected. We propose to create detailed numerical models of GCs to systematically study the effect of retained BHs on the 1) lifetime and survival of host GCs; 2) GC properties observable by HST; and 3) production and radial distibutions of tracers of dynamical interactions (e.g., blue stragglers, sub-subgiants, interacting binaries, and binary fraction). Our study will identify key observable GC properties that most reliably indicate the presence or absence of a large number of bound BHs. We will compare these properties with the wealth of GC data obtained by HST observations of GC cores to identify specific Galactic GCs that are most likely to host large populations of BHs at present. Our results will guide future observational searches for BH candidates in GCs in both the Milky Way and other galaxies. Moreover, these detailed models will provide unprecedented constraints on the number, radial distribution, binarity, dynamical and stellar evolution history for BHs in star clusters, thus connecting HST observations of GCs directly to LIGO astrophysics.
Effective start/end date10/1/1612/31/17


  • Space Telescope Science Institute (HST-AR-14555.001-A-Amend. 1 // NAS5-2)
  • National Aeronautics and Space Administration (HST-AR-14555.001-A-Amend. 1 // NAS5-2)


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