Black hole discs in dense stellar systems

最近引力波的发现为理解宇宙开辟了新的视野。这些测量揭示了大量的恒星质量黑洞合并。最大的挑战是理解可能导致合并的天体物理机制。它们的天体物理起源的现有理论模型目前要么非常不完整，要么与数据紧张（巴拉克+ 2019）。一个有趣的可能性是，观测到的黑洞合并是在密集的恒星系统中产生的，比如球状星团或星系核，其中包含有或没有气体吸积盘的超大质量黑洞。在这些系统中，恒星质量的黑洞下沉到星团的中心，并经历频繁的动态相遇，形成双星，最终可能合并并产生引力波发射。在这个项目中，学生将与Bence Kocsis教授一起建立一个包含恒星质量黑洞的密集恒星系统的综合动力学模型。黑洞预计会形成一个扁平的盘状结构，由于周围星团的各向异性波动而扭曲和扭曲。我们将结合分析和数值方法，包括统计力学、动力学理论和n体模拟，来确定这些子系统是否可能长期存在，它如何影响星团的演化，研究双星的形成和演化，并检查对电磁和引力波天文台的影响。

The recent discovery of gravitational waves opened new horizons for understanding the Universe. The measurements have unveiled an abundant population of stellar mass black hole mergers. The great challenge is to understand the possible astrophysical mechanisms that may lead to mergers. The existing theoretical models of their astrophysical origin are currently either highly incomplete or in tension with data (Barack+ 2019). An interesting possibility is that the observed black hole mergers are generated in dense stellar systems such as globular clusters or galactic nuclei harboring a supermassive black hole with or without a gaseous accretion disk. In these systems, stellar mass black holes sink to the center of the cluster and undergo frequent dynamical encounters, forming binaries, which may eventually merge and produce gravitational wave emission. In this project, the student will work with Prof. Bence Kocsis to build a comprehensive dynamical model of dense stellar systems with a population of stellar mass black holes. The black holes are expected to settle to a flattened disk-like structure which gets twisted and warped due to the fluctuating anisotropy of the otherwise spherical surrounding star cluster. We will use a combination of analytic and numerical methods including statistical mechanics, kinetic theory, and N-body simulations to determine if such subsystems may be long-lived, how it affects the evolution of the cluster, study the formation and evolution of binaries, and examine the implications for electromagnetic and gravitational wave observatories.