Compact Object Binary Mergers Driven By Cluster Tides: A New Channel for LIGO/Virgo Gravitational-wave Events
Compact Object Binary Mergers Driven By Cluster Tides: A New Channel for LIGO/Virgo Gravitational-wave Events
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DOI：
10.3847/2041-8213/ab3468
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
C. Hamilton;R. Rafikov
中科院分区：
文献类型：
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作者：
C. Hamilton;R. Rafikov
LIGO/Virgo探测到的双星黑洞（BH）和中子星（NS）合并产生的引力波（GW）激发了人们对双星起源的兴趣。致密的恒星系统球状星团和核星星团是致密天体双星形成和合并演化的自然场所。在这里，我们探索了一个新的渠道，在集群中的二进制合并的生产，其中集群的潮汐场世俗驱动器的二进制高偏心率（即使在没有一个中央大规模BH），直到GW排放变得重要。我们采用最近发展的长期理论的集群潮汐驱动的二进制演化计算目前的合并率BH-BH，NS-BH和NS-NS的二进制，不同的集群潜力和中心浓度的二进制人口（但忽略集群的演变和恒星飞掠现在）。与其他机制不同，这种新的动态通道可以产生大量的合并到几个秒差距的集群为中心的距离。对于NS-NS双星，我们发现球状星团的合并速率在0.01-0.07 Gpc−3 yr−1之间，而尖形核星团的合并速率在0.1-0.2 Gpc−3 yr−1之间。对于NS-BH和BH-BH双星，我们发现球状星团的合并率很小，但尖核星团的合并率为0.1-0.2 Gpc−3 yr−1，对观测到的LIGO/Virgo比率的贡献为几个百分点。因此，集群潮汐驱动的合并构成了一个新的渠道，可以进一步探索与当前和未来的GW探测器。
The detections of gravitational waves (GWs) produced in mergers of binary black holes (BHs) and neutron stars (NSs) by LIGO/Virgo have stimulated interest in the origin of the progenitor binaries. Dense stellar systems—globular and nuclear star clusters—are natural sites of compact object binary formation and evolution toward merger. Here we explore a new channel for the production of binary mergers in clusters, in which the tidal field of the cluster secularly drives the binary to high eccentricity (even in the absence of a central massive BH) until GW emission becomes important. We employ the recently developed secular theory of cluster tide-driven binary evolution to compute present day merger rates for BH–BH, NS–BH, and NS–NS binaries, varying cluster potential and central concentration of the binary population (but ignoring cluster evolution and stellar flybys for now). Unlike other mechanisms, this new dynamical channel can produce a significant number of mergers out to cluster-centric distances of several parsecs. For NS–NS binaries we find merger rates in the range of 0.01–0.07 Gpc−3 yr−1 from globular clusters and 0.1–0.2 Gpc−3 yr−1 from cusped nuclear clusters. For NS–BH and BH–BH binaries we find small merger rates from globular clusters, but a rate of 0.1–0.2 Gpc−3 yr−1 from cusped nuclear clusters, contributing to the observed LIGO/Virgo rate at the level of several percent. Therefore, cluster tide-driven mergers constitute a new channel that can be further explored with current and future GW detectors.