地球探测器观测到的银河系核引力波捕获的高偏心率和高质量特征
High Eccentricities and High Masses Characterize Gravitational-wave Captures in Galactic Nuclei as Seen by Earth-based Detectors
摘要：
在星系核的单-单近距离碰撞过程中，引力波的发射导致了高偏心恒星质量黑洞双星的形成和快速合并。物理参数的独特分布使得有可能在统计上将这一来源人口与其他来源人口区分开来。以前的研究确定了预期的二元参数分布，这个源人口在单一的GN。在这里，我们考虑到动力学摩擦，后牛顿修正和观测偏差的影响，以确定从宇宙中的所有GN检测到的源的参数分布。我们发现，总的二进制质量分布检测合并强烈倾向于更高的质量。GW的初始峰值频率分布在1-70 Hz之间，约50%的GW捕获源来自10 Hz以上，e >~ 0.95。当首次进入LIGO/Virgo/KAGRA波段时，超过92%的源满足e_10Hz > 0.1，超过一半的源满足e_10Hz > 0.8。当近心达到10 GM/c^2时，超过70%的源的偏心率满足e_10M > 0.1，这使得GN中的单个GW捕获事件成为宇宙中目前已知的恒星质量双星BH合并通道中最偏心的源群。我们确定总质量，质量比，源检测距离，和偏心率e_10Hz和e_10M之间的相关性。最近测得的GW 190521的源参数接近理论分布的峰值，估计宿主环境的逃逸速度约为7.5x10^3 km/s - 1.2x10^4 km/s，使该源成为该天体物理合并通道的候选者。
英文摘要：
The emission of gravitational waves (GWs) during single-single close encounters in galactic nuclei (GNs) leads to the formation and rapid merger of highly eccentric stellar-mass black hole (BH) binaries. The distinct distribution of physical parameters makes it possible to statistically distinguish this source population from others. Previous studies determined the expected binary parameter distribution for this source population in single GNs. Here we take into account the effects of dynamical friction, post-Newtonian corrections, and observational bias to determine the detected sources' parameter-distributions from all GNs in the Universe. We find that the total binary mass distribution of detected mergers is strongly tilted towards higher masses. The distribution of initial peak GW frequency is remarkably high between 1-70 Hz, ~50% of GW capture sources form above 10 Hz with e >~ 0.95. The eccentricity when first entering the LIGO/Virgo/KAGRA band satisfies e_10Hz > 0.1 for over 92% of sources and e_10Hz > 0.8 for more than half of the sources. At the point when the pericenter reaches 10 GM/c^2 the eccentricity satisfies e_10M > 0.1 for over ~70% of the sources, making single-single GW capture events in GNs the most eccentric source population among the currently known stellar-mass binary BH merger channels in the Universe. We identify correlations between total mass, mass ratio, source detection distance, and eccentricities e_10Hz and e_10M. The recently measured source parameters of GW190521 lie close to the peak of the theoretical distributions and the estimated escape speed of the host environment is ~7.5x10^3 km/s - 1.2x10^4 km/s, making this source a candidate for this astrophysical merger channel.
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