Stellar black hole binary mergers in open clusters

S. Rastello*, P. Amaro-Seoane, M. Arca-Sedda, Capuzzo-Dolcettar, G. Fragione, I. Tosta E. Melo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


In this paper we study the evolution of a primordial black hole binary (BHB) in a sample of over 1500 direct-summation N-body simulations of small- and intermediate-size isolated star clusters as proxies of Galactic open clusters. The BHBs have masses in the range of the first LIGO/Virgo detections. Some of our models show a significant hardening of the BHB in a relatively short time. Some of them merge within the cluster, while ejected binaries, typically, have exceedingly long merger time-scales. The perturbation of stars around BHB systems is key to induce their coalescence. The BHBs which merge in the cluster could be detected with a delay of a few years between space detectors, as future LISA, and ground-based ones, due to their relatively high eccentricity. Under our assumptions, we estimate a BHB merger rate of Rmrg ~ 2 yr-1 Gpc-3. We see that in many cases the BHB triggers tidal disruption events which, however, are not linked to the GW emission. Open cluster-like systems are, hence, a promising environment for GWs from BHBs and tidal disruptions.

Original languageEnglish (US)
Pages (from-to)1233-1246
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Feb 11 2019
Externally publishedYes


  • Black hole physics - gravitational waves - stars
  • Black holes - stars
  • General
  • Kinematics and dynamics - open clusters and associations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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