Black holes: The next generation - Repeated mergers in dense star clusters and their gravitational-wave properties

Carl L. Rodriguez, Michael Zevin, Pau Amaro-Seoane, Sourav Chatterjee, Kyle Kremer, Frederic A. Rasio, Claire S. Ye

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

When two black holes merge in a dense star cluster, they form a new black hole with a well-defined mass and spin. If that "second-generation" black hole remains in the cluster, it will continue to participate in dynamical encounters, form binaries, and potentially merge again. Using a grid of 96 dynamical models of dense star clusters and a cosmological model of cluster formation, we explore the production of binary black hole mergers where at least one component of the binary was forged in a previous merger. We create four hypothetical universes where every black hole born in the collapse of a massive star has a dimensionless Kerr spin parameter, χbirth, of 0.0, 0.1, 0.2, or 0.5. We show that if all stellar-born black holes are nonspinning (χbirth=0.0), then more than 10% of merging binary black holes from clusters have components formed from previous mergers, accounting for more than 20% of the mergers from globular clusters detectable by LIGO/Virgo. Furthermore, nearly 7% of detectable mergers would have a component with a mass 55 M, placing it clearly in the mass "gap" region where black holes cannot form from isolated collapsing stars due to the pulsational-pair instability mechanism. On the other hand, if black holes are born spinning, then the contribution from these second-generation mergers decreases, making up as little as 1% of all detections from globular clusters when χbirth=0.5. We make quantitative predictions for the detected masses, mass ratios, and spin properties of first- and second-generation mergers from dense star clusters, and show how these distributions are highly sensitive to the birth spins of black holes.

Original languageEnglish (US)
Article number043027
JournalPhysical Review D
Volume100
Issue number4
DOIs
StatePublished - Aug 27 2019

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star clusters
gravitational waves
globular clusters
LIGO (observatory)
massive stars
encounters
mass ratios
metal spinning
universe
grids
stars

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Rodriguez, Carl L. ; Zevin, Michael ; Amaro-Seoane, Pau ; Chatterjee, Sourav ; Kremer, Kyle ; Rasio, Frederic A. ; Ye, Claire S. / Black holes : The next generation - Repeated mergers in dense star clusters and their gravitational-wave properties. In: Physical Review D. 2019 ; Vol. 100, No. 4.
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Black holes : The next generation - Repeated mergers in dense star clusters and their gravitational-wave properties. / Rodriguez, Carl L.; Zevin, Michael; Amaro-Seoane, Pau; Chatterjee, Sourav; Kremer, Kyle; Rasio, Frederic A.; Ye, Claire S.

In: Physical Review D, Vol. 100, No. 4, 043027, 27.08.2019.

Research output: Contribution to journalArticle

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