TY - JOUR
T1 - Eccentric binary black hole mergers in globular clusters hosting intermediate-mass black holes
AU - Fragione, Giacomo
AU - Bromberg, Omer
N1 - Funding Information:
We thank the referee for a constructive report. GF is supported by the Foreign Postdoctoral Fellowship Program of the Israel Academy of Sciences and Humanities. GF also acknowledges support from an Arskin postdoctoral fellowship. Simulations were run on the Astric cluster at the Hebrew University of Jerusalem.
Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2019/9/21
Y1 - 2019/9/21
N2 - Globular clusters (GCs) may harbour intermediate-mass black holes (IMBHs) at their centres. In these dynamically active environments, stellar-mass black holes (SBHs) sink to the centre soon after formation, due to dynamical friction and start interacting among themselves and with the central IMBH. Likely, some of the SBHs will form bound systems with the IMBH. A fraction of those will be triple systems composed of binary SBHs and the IMBH acting as a third distant perturber. If the SBH binary orbit is sufficiently inclined, it can develop Lidov–Kozai (LK) oscillations, which can drive the system to high eccentricities and eventually to a merger due to gravitational wave (GW) emission on short time-scales. In this work, we focus on the dynamics of the IMBH–SBH–SBH triples and illustrate that these systems can be possible sources of GWs. A distinctive signature of this scenario is that a considerable fraction of these mergers are highly eccentric when entering the LIGO band (10 Hz). Assuming that ∼ 20 per cent of GCs host IMBHs and a GC density in the range nGC = 0.32–2.31 Mpc−3, we have estimated a rate ⌈ = 0.06–0.46 Gpc−3 yr−1 of these events. This suggests that dynamically driven binary SBH mergers in this scenario could contribute to the merger events observed by LIGO/VIRGO. Full N-body simulations of GCs harbouring IMBHs are highly desirable to give a more precise constrain on this scenario.
AB - Globular clusters (GCs) may harbour intermediate-mass black holes (IMBHs) at their centres. In these dynamically active environments, stellar-mass black holes (SBHs) sink to the centre soon after formation, due to dynamical friction and start interacting among themselves and with the central IMBH. Likely, some of the SBHs will form bound systems with the IMBH. A fraction of those will be triple systems composed of binary SBHs and the IMBH acting as a third distant perturber. If the SBH binary orbit is sufficiently inclined, it can develop Lidov–Kozai (LK) oscillations, which can drive the system to high eccentricities and eventually to a merger due to gravitational wave (GW) emission on short time-scales. In this work, we focus on the dynamics of the IMBH–SBH–SBH triples and illustrate that these systems can be possible sources of GWs. A distinctive signature of this scenario is that a considerable fraction of these mergers are highly eccentric when entering the LIGO band (10 Hz). Assuming that ∼ 20 per cent of GCs host IMBHs and a GC density in the range nGC = 0.32–2.31 Mpc−3, we have estimated a rate ⌈ = 0.06–0.46 Gpc−3 yr−1 of these events. This suggests that dynamically driven binary SBH mergers in this scenario could contribute to the merger events observed by LIGO/VIRGO. Full N-body simulations of GCs harbouring IMBHs are highly desirable to give a more precise constrain on this scenario.
KW - Galaxies: star clusters: general
KW - Galaxy: centre
KW - Galaxy: kinematics and dynamics
KW - Stars: black holes
KW - Stars: kinematics and dynamics
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U2 - 10.1093/mnras/stz2024
DO - 10.1093/mnras/stz2024
M3 - Article
AN - SCOPUS:85071993044
SN - 0035-8711
VL - 488
SP - 4370
EP - 4377
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -