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Black Hole Mergers from Hierarchical Triples in Dense Star Clusters

Martinez, Miguel A. S. and Fragione, Giacomo and Kremer, Kyle and Chatterjee, Sourav and Rodriguez, Carl L. and Samsing, Johan and Ye, Claire S. and Weatherford, Newlin C. and Zevin, Michael and Naoz, Smadar and Rasio, Frederic A. (2020) Black Hole Mergers from Hierarchical Triples in Dense Star Clusters. Astrophysical Journal, 903 (1). Art. No. 67. ISSN 1538-4357.

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Hierarchical triples are expected to be produced by the frequent binary-mediated interactions in the cores of globular clusters. In some of these triples, the tertiary companion can drive the inner binary to merger following large eccentricity oscillations, as a result of the eccentric Kozai–Lidov mechanism. In this paper, we study the dynamics and merger rates of black hole (BH) hierarchical triples, formed via binary–binary encounters in the CMC Cluster Catalog, a suite of cluster simulations with present-day properties representative of the Milky Way's globular clusters. We compare the properties of the mergers from triples to the other merger channels in dense star clusters, and show that triple systems do not produce significant differences in terms of mass and effective spin distribution. However, they represent an important pathway for forming eccentric mergers, which could be detected by LIGO–Virgo/Kamioka Gravitational-Wave Detector (LVK), and future missions such as LISA and the DECi-hertz Interferometer Gravitational wave Observatory. We derive a conservative lower limit for the merger rate from this channel of 0.35 Gpc⁻³ yr⁻¹ in the local universe and up to ~9% of these events may have a detectable eccentricity at LVK design sensitivity. Additionally, we find that triple systems could play an important role in retaining second-generation BHs, which can later merge again in the core of the host cluster.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Martinez, Miguel A. S.0000-0001-5285-4735
Fragione, Giacomo0000-0002-7330-027X
Kremer, Kyle0000-0002-4086-3180
Chatterjee, Sourav0000-0002-3680-2684
Rodriguez, Carl L.0000-0003-4175-8881
Samsing, Johan0000-0003-0607-8741
Ye, Claire S.0000-0001-9582-881X
Weatherford, Newlin C.0000-0002-9660-9085
Zevin, Michael0000-0002-0147-0835
Naoz, Smadar0000-0002-9802-9279
Rasio, Frederic A.0000-0002-7132-418X
Additional Information:© 2020. The American Astronomical Society. Received 2020 July 3; revised 2020 September 16; accepted 2020 September 17; published 2020 November 3. We thank Fabio Antonini and Nathan Leigh for useful discussions. Our work was supported by NSF grant AST-1716762. Computations were supported in part through the resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work also used computing resources at CIERA funded by NSF grant PHY-1726951 and computing resources provided by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics. G.F. acknowledges support from a CIERA Fellowship at Northwestern University. K.K. acknowledges support from an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2001751. S.C. acknowledges support from the Department of Atomic Energy, Government of India, under project no. 12-R&D-TFR-5.02-0200. J.S. acknowledges support from the European Unions Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 844629. S.N. acknowledge the partial support of NASA grant no. 80NSSC19K0321 and no. 80NSSC20K0505. S.N. also thanks Howard and Astrid Preston for their generous support. Software: Kozai (Rodriguez & Antonini 2018; Rodriguez et al. 2018), OSPE (Naoz et al. 2013a), ARWV 1.7 (Mikkola & Merritt 2006, 2008; Chassonnery et al. 2019).
Funding AgencyGrant Number
Northwestern UniversityUNSPECIFIED
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
NSF Astronomy and Astrophysics FellowshipAST-2001751
Department of Atomic Energy (India)12-R&D-TFR-5.02-0200
Marie Curie Fellowship844629
Howard and Astrid PrestonUNSPECIFIED
Subject Keywords:Astrophysical black holes ; Black holes ; Stellar mass black holes ; Gravitational wave astronomy ; Gravitational wave detectors ; Gravitational wave sources ; Gravitational waves ; Globular star clusters ; Star clusters ; Trinary stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Astrophysical black holes (98); Black holes (162); Stellar mass black holes (1611); Gravitational wave astronomy (675); Gravitational wave detectors (676); Gravitational wave sources (677); Gravitational waves (678);
Record Number:CaltechAUTHORS:20201105-152206237
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Official Citation:Miguel A. S. Martinez et al 2020 ApJ 903 67
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106458
Deposited By: George Porter
Deposited On:06 Nov 2020 15:40
Last Modified:06 Nov 2020 15:40

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