TY - JOUR
T1 - Black hole and neutron star mergers in galactic nuclei
T2 - The role of triples
AU - Fragione, Giacomo
AU - Leigh, Nathan W.C.
AU - Perna, Rosalba
N1 - Funding Information:
We thank the anonymous referee for useful comments. 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. NL and RP acknowledge support by NSF award AST-1616157. GF thanks Seppo Mikkola for helpful discussions on the use of the code ARCHAIN. Simulations were run on the Astric cluster at the Hebrew University of Jerusalem. The Center for Computational Astrophysics at the Flatiron Institute is supported by the Simons Foundation.
Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2019/9/11
Y1 - 2019/9/11
N2 - Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are thought to contain large numbers of black holes (BHs) and neutron stars (NSs), a fraction of which form binaries and could merge by Kozai–Lidov oscillations (KL). Triple compact objects are likely to be present, given what is known about the multiplicity of massive stars, whose life ends either as an NS or a BH. In this paper, we present a new possible scenario for merging BHs and NSs in galactic nuclei. We study the evolution of a triple black hole (BH) or neutron star (NS) system orbiting an SMBH in a galactic nucleus by means of direct high-precision N-body simulations, including post-Newtonian terms. We find that the four-body dynamical interactions can increase the KL angle window for mergers compared to the binary case and make BH and NS binaries merge on shorter time-scales. We show that the merger fraction can be up to ~5–8 times higher for triples than for binaries. Therefore, even if the triple fraction is only ~10–20 per cent of the binary fraction, they could contribute to the merger events observed by LIGO/VIRGO in comparable numbers.
AB - Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are thought to contain large numbers of black holes (BHs) and neutron stars (NSs), a fraction of which form binaries and could merge by Kozai–Lidov oscillations (KL). Triple compact objects are likely to be present, given what is known about the multiplicity of massive stars, whose life ends either as an NS or a BH. In this paper, we present a new possible scenario for merging BHs and NSs in galactic nuclei. We study the evolution of a triple black hole (BH) or neutron star (NS) system orbiting an SMBH in a galactic nucleus by means of direct high-precision N-body simulations, including post-Newtonian terms. We find that the four-body dynamical interactions can increase the KL angle window for mergers compared to the binary case and make BH and NS binaries merge on shorter time-scales. We show that the merger fraction can be up to ~5–8 times higher for triples than for binaries. Therefore, even if the triple fraction is only ~10–20 per cent of the binary fraction, they could contribute to the merger events observed by LIGO/VIRGO in comparable numbers.
KW - Galaxies: star clusters: general
KW - Galaxy: centre
KW - Galaxy: kinematics and dynamics
KW - Stars: kinematics and dynamics
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U2 - 10.1093/mnras/stz1803
DO - 10.1093/mnras/stz1803
M3 - Article
AN - SCOPUS:85071978060
SN - 0035-8711
VL - 488
SP - 2825
EP - 2835
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -