TY - JOUR

T1 - Black Hole Mergers from Hierarchical Triples in Dense Star Clusters

AU - Martinez, Miguel A. S.

AU - Fragione, Giacomo

AU - Kremer, Kyle

AU - Chatterjee, Sourav

AU - Rodriguez, Carl L.

AU - Samsing, Johan

AU - Ye, Claire S.

AU - Weatherford, Newlin C.

AU - Zevin, Michael

AU - Naoz, Smadar

AU - Rasio, Frederic A.

PY - 2020/11/1

Y1 - 2020/11/1

N2 - 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 similar 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.

AB - 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 similar 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.

KW - Astrophysical black holes

KW - Black holes

KW - Stellar mass black holes

KW - Gravitational wave astronomy

KW - Gravitational wave detectors

KW - Gravitational wave sources

KW - Gravitational waves

KW - Globular star clusters

KW - Star clusters

KW - Trinary stars

KW - MONTE-CARLO SIMULATIONS

KW - GRAVITATIONAL-WAVE GENERATION

KW - KOZAI-LIDOV OSCILLATIONS

KW - OPEN STELLAR CLUSTERS

KW - GLOBULAR-CLUSTERS

KW - ALGORITHMIC REGULARIZATION

KW - CHAOTIC DYNAMICS

KW - BINARY-BINARY

KW - EVOLUTION

KW - MASS

U2 - 10.3847/1538-4357/abba25

DO - 10.3847/1538-4357/abba25

M3 - Journal article

VL - 903

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 67

ER -