Numerical studies of binary black hole dynamics and waveforms

美国国家科学基金会的LIGO引力波探测器是世界上许多新的和计划中的设施之一，这些设施旨在直接探测和测量引力波。对引力波的观测将使我们能够研究诸如黑洞、超新星、中子星、坍缩和伽马射线暴等外来物体，从而为宇宙打开一扇新的窗口。该项目的研究目的是在计算机上模拟引力辐射最重要的来源之一，即由黑洞组成的双星系统。在这样的系统中，黑洞会相互旋转，直到形成一个更大的合并黑洞。这个项目的计划是研究这些系统，以便对它们激发和合并时发出的引力波做出预测。在这项工作的过程中，将解决几个关键的物理问题：(i)两个黑洞合并后可能的最大反冲速度是多少？（ii）在什么构型下会发生自旋翻转？（iii）最终合并黑洞可达到的最大角动量是多少？（iv）模拟对初始条件的选择有多敏感？这项工作很重要，因为引力波探测器（如LIGO）需要对引力波进行可靠的理论预测，这些预测将在不久的将来被观测到。这项工作的其他方面对各种天体物理模型都有影响。例如，最终黑洞的后坐力大小是超大质量黑洞的宇宙学演化或密集星团中中等质量黑洞的生长和保留的重要输入参数。此外，这项研究对从数值和数学相对论到引力波天体物理学的协同努力做出了关键贡献。这项研究是与德国耶拿大学的相对论小组合作进行的。通过教师、博士后和学生的访问与该机构进行定期交流，将对佛罗里达大西洋大学的学生和耶拿的学生都有教育上的好处。

The NSF's LIGO gravitational wave detectors are among a number of new and planned facilities all over the world which are designed to directly detect and measure gravitational waves. The observation of gravitational waves will open a new window on the universe by enabling us to study exotic objects such as black holes, supernovae, neutron stars, collapsars and gamma-ray bursts. The research in this project is aimed at simulating on the computer what is expected to be one of the most important sources of gravitational radiation, namely binary systems consisting of black holes. The black holes in such systems spiral towards each other until they form a larger merged black hole. The plan for this project is to investigate these systems in order to make predictions about the gravitational waves emitted during their inspiral and merger. In the course of this work, several key physics questions will be addressed: (i) What is the maximum possible recoil velocity after the two black holes have merged? (ii) For what configurations can spin flips occur? (iii) What is the maximum achievable angular momentum of the final merged black hole? (iv) How sensitive are the simulations to the choice of the initial conditions?This work is important because gravitational wave detectors (such as LIGO) need reliable theoretical predictions of the gravitational waves which will be observed in the near future. Other aspects of this work have implications for a variety of astrophysical models. For example, the magnitude of the recoil of the final black hole is an important input parameter for the cosmological evolution of supermassive black holes or the growth and retention of intermediate-mass black holes in dense stellar clusters. In addition, this investigation makes key contributions to synergistic efforts, ranging from numerical and mathematical relativity to gravitational wave astrophysics. It is carried out in collaboration with the relativity group at the University of Jena in Germany. Regular exchange with this institution through visits by faculty, post-docs and students will have educational benefits for both the students at Florida Atlantic University and the students in Jena.