Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves
Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves
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DOI：
10.3847/1538-4357/aba518
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发表时间：
2020-04
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影响因子：
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通讯作者：
Chase Kimball;C. Talbot;Christopher P. L. Berry;M. Carney;M. Zevin;E. Thrane;V. Kalogera
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文献类型：
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作者：
Chase Kimball;C. Talbot;Christopher P. L. Berry;M. Carney;M. Zevin;E. Thrane;V. Kalogera
在稠密的恒星环境中，双黑洞合并的合并产物可能会经历额外的合并。这些等级合并自然会比第一代恒星黑洞的质量更高。分层合并的组件预计将有显着的特征自旋，由以前的合并的轨道角动量印记。然而，由于第一代黑洞的人口属性是不确定的，很难知道任何给定的合并是第一代还是分层的。我们利用引力波的观测来重建二元黑洞的质量和自旋谱的人口，包括层次合并的可能性。我们采用一个唯象模型，从球状星团的模拟中捕捉合并二元黑洞的性质。受最近关于低自旋黑洞形成的工作的启发，我们包含了一个零自旋子种群。我们分析了来自LIGO和Virgo的前两次观测运行的二元黑洞，发现这个目录与没有层次合并是一致的。我们发现这个星表中质量最大的系统，GW170729，很可能是第一代合并，假设质量为5 × 105M的球状星团，有4%的概率是等级合并。使用我们的模型，我们发现，99%的第一代黑洞在合并的二进制文件的质量低于M，和近零组件自旋的二进制文件的比例小于（90%的概率）。接下来的观测将确定分层合并是否是引力波的常见来源。
In dense stellar environments, the merger products of binary black hole mergers may undergo additional mergers. These hierarchical mergers are naturally expected to have higher masses than the first generation of black holes made from stars. The components of hierarchical mergers are expected to have significant characteristic spins, imprinted by the orbital angular momentum of the previous mergers. However, since the population properties of first-generation black holes are uncertain, it is difficult to know if any given merger is first-generation or hierarchical. We use observations of gravitational waves to reconstruct the binary black hole mass and spin spectrum of a population including the possibility of hierarchical mergers. We employ a phenomenological model that captures the properties of merging binary black holes from simulations of globular clusters. Inspired by recent work on the formation of low-spin black holes, we include a zero-spin subpopulation. We analyze binary black holes from LIGO and Virgo’s first two observing runs, and find that this catalog is consistent with having no hierarchical mergers. We find that the most massive system in this catalog, GW170729, is mostly likely a first-generation merger, having a 4% probability of being a hierarchical merger assuming a 5 × 105M⊙ globular cluster mass. Using our model, we find that 99% of first-generation black holes in coalescing binaries have masses below M⊙, and the fraction of binaries with near-zero component spins is less than (90% probability). Upcoming observations will determine if hierarchical mergers are a common source of gravitational waves.