Black Hole Mergers in Galactic Nuclei Induced by the Eccentric Kozai–Lidov Effect

By Bao-Minh Hoang, S. Naoz, B. Kocsis, F. Rasio, F. Dosopoulou. 2017

245 citations recorded by the source corpus.

Nuclear star clusters around a central massive black hole (MBH) are expected to be abundant in stellar black hole (BH) remnants and BH–BH binaries. These binaries form a hierarchical triple system with the central MBH, and gravitational perturbations from the MBH can cause high-eccentricity excitation in the BH–BH binary orbit. During this process, the eccentricity may approach unity, and the pericenter distance may become sufficiently small so that gravitational-wave emission drives the BH–BH binary to merge. In this work, we construct a simple proof-of-concept model for this process, and specifically, we study the eccentric Kozai–Lidov mechanism in unequal-mass, soft BH–BH binaries. Our model is based on a set of Monte Carlo simulations for BH–BH binaries in galactic nuclei, taking into account quadrupole- and octupole-level secular perturbations, general relativistic precession, and gravitational-wave emission. For a typical steady-state number of BH–BH binaries, our model predicts a total merger rate of ∼1–3 −3 −1, depending on the assumed density profile in the nucleus. Thus, our mechanism could potentially compete with other dynamical formation processes for merging BH–BH binaries, such as the interactions of stellar BHs in globular clusters or in nuclear star clusters without an MBH.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/489ab9a842fb8fdb6728d80bc7f1856ab2d91252

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In Astronomy and Astrophysics

1. B. Kocsis
2. Zoltán Haiman
3. Floor Broekgaarden
4. D. D’Orazio
5. J. Samsing
6. Ilya Mandel
7. P. Raffai
8. Z. Frei

Citations in the corpus

• Rates of compact object coalescences (2021, background): “…may operate in a number of regimes, from isolated stellar triples (Silsbee and Tremaine, 2017) to dynamically formed triples in clusters (Antonini et al., 2016) to triples in which the outer companion is a massive black hole in a galactic center (Antonini and Perets, 2012; Hoang et al., 2018).”
• Black hole and neutron star mergers in galactic nuclei (2018, background): “1 pc; Antonini & Perets 2012; Hoang et al. 2018; Fragione et al. 2018; Hamers et al. 2018).”
• Eccentric Black Hole Gravitational-wave Capture Sources in Galactic Nuclei: Distribution of Binary Parameters (2017, methodology): “…BH binaries forming via the Kozai–Lidov mechanism in GCs (Antonini et al. 2014, 2016; Rodriguez et al. 2016a, 2016b) and GNs (Antonini & Perets 2012; Hoang et al. 2018), and non-spherical nuclear star clusters may produce BH–BH binary merger rates of up to 15 Gpc−3 yr−1 (Petrovich & Antonini…”
• Formation and Evolution of Compact-object Binaries in AGN Disks (2019, background): “…2016), evolution of triple or quadruple systems (Antonini et al. 2017; Liu & Lai 2017, 2018, 2019; Silsbee & Tremaine 2017; Arca-Sedda et al. 2018; Hoang et al. 2018b; Randall & Xianyu 2018; Fragione & Kocsis 2019; Fragione et al. 2019; Michaely & Perets 2019), gravitational capture (O’Leary et…”
• Black Hole Mergers From Globular Clusters Observable by LISA I: Eccentric Sources Originating From Relativistic N-body Dynamics (2018, background): “…discs (Bartos et al. 2017; Stone et al. 2017; McKernan et al. 2017), galactic nuclei (O’Leary et al. 2009; Hong & Lee 2015; VanLandingham et al. 2016; Antonini & Rasio 2016; Hoang et al. 2017), and very massive stellar mergers (Loeb 2016; Woosley 2016; Janiuk et al. 2017; D’Orazio & Loeb 2017).”