Gravitational waves from $\sim 90$ black holes binary systems have currently been detected by the LIGO and Virgo experiments, and their progenitors' properties inferred. This allowed the scientific community to draw conclusions on the formation channels of black holes in binaries, informing population models and -- at times -- defying our understanding of black hole astrophysics. The most challenging event detected so far is the short duration gravitational-wave transient GW190521. We analyze this signal under the hypothesis that it was generated by the merger of two nonspinning black holes on hyperbolic orbits. The best configuration matching the data corresponds to two black holes of source frame masses of $81^{+62}_{-25}M_\odot$ and $52^{+32}_{-32}M_\odot$ undergoing two encounters and then merging into an intermediate-mass black hole. We find that the hyperbolic merger hypothesis is favored with respect to a quasi-circular merger with precessing spins with Bayes' factors larger than 4300 to 1, although this number will be reduced by the currently uncertain prior odds. Our results suggest that GW190521 might be the first gravitational-wave detection from the dynamical capture of two stellar-mass nonspinning black holes.
Effects of dynamical capture on two equal-mass nonspinning black holes
Universidad Autónoma de Madrid（马德里自治大学）；Observatoire Astronomique de Strasbourg, CNRS, Université de Strasbourg（斯特拉斯堡天文台，法国国家科学研究中心，斯特拉斯堡大学）；Instituto de Física Teórica UAM-CSIC, Universidad Autónoma de Madrid（马德里自治大学-西班牙国家研究委员会理论物理研究所）
Self-force as a cosmic censor in the Kerr overspinning problem
众所周知，一个接近极值的克尔黑洞可以通过捕获一个测试粒子而旋转到超过其极值极限。在这里，我们表明，一旦从粒子的自身重力的反作用是适当地考虑，总是避免过度自旋。我们专注于非自旋，不带电，沿着赤道平面抛出的大质量粒子，并在一阶自作用力近似下工作（即，我们通过粒子能量和黑洞质量之间的比率（假设很小）的线性顺序，包括对粒子加速度的所有相关修正。我们的计算是我们两个人最近分析的数值实现[Phys.修订版本\ D { \bf 91}，104024（2015）]，其中为捕获场景制定了一个必要和充分的“审查”条件，涉及在极值极限下在不稳定圆形测地线的单参数族上计算的某些自力量。自作用力信息既考虑了辐射损失，又考虑了对碰撞参量临界值的有限质量修正。在这里，我们获得了所需的自作用力数据，并提出了强有力的证据表明，捕获的粒子永远不会驱动黑洞超过其极限。然而，我们表明，在我们的一阶自作用力近似，它是可能达到极值极限与适当的选择初始轨道参数。要排除这种可能性，需要（目前无法获得）关于高阶自作用力修正的信息。
General Fourier expansion of post-Newtonian binary dynamics based on a quasi-Keplerian framework
Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿天文与天体物理研究所）；Department of Astronomy, Beijing Normal University（北京师范大学天文系）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, UCAS（中国科学院大学杭州高等研究院基础科学与数学学院）
Towards long and accurate numerical relativity waveforms of binary black holes beyond general relativity
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））；Cornell University（康奈尔大学）；California State University Fullerton（加州州立大学富勒顿分校）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；California Institute of Technology（加州理工学院）
Inferring host environment properties and gravitational-wave decay time from the eccentricity measurement of dynamically captured binaries
Chennai Mathematical Institute（金奈数学研究所）；Cardiff University（卡迪夫大学）；Montclair State University（蒙克莱尔州立大学）；Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））；Leibniz Universität Hannover（汉诺威莱布尼茨大学）
