CDI-Type II: Collaborative Research: Computing Supermassive Black Hole Mergers in Astrophysics

超大质量黑洞合并被认为发生的频率很高，但通过引力波观测直接探测到黑洞仍然是未来的希望。找到它们的另一种途径是通过光子观测它们对附近气体的影响，但关于它们可能产生什么样的光，人们几乎不确定。为了解决这一问题，本项目对这些事件的电磁输出进行了系统的理论研究，从双星黑洞的前驱阶段，到事件本身，并包括合并后的弛豫阶段。由于辐射的光的数量和性质在根本上取决于从黑洞到给定距离的质量有多大，当二元分离和牛顿动力学应用时，系统的初始演化与广义相对论控制系统时的合并本身之间的协调是该计划的重要组成部分。通过对这些系统的常规望远镜观测，目的是创建一个全新的子领域--合并黑洞的天文学。只有通过构建高度复杂的计算系统，才能实现这些科学目标。高性能的计算是至关重要的，因为跟踪这些事件的动力学涉及到同时求解一般相对论时空中的辐射输运方程和磁流体动力学(MHD)方程，以及高度非线性的爱因斯坦场方程。数据通信要求也极具挑战性，因为即使是定义黑洞合并的动态时空也可能需要高达数PB的空间。因此，这项工作是非常多学科的，因为需要多种专业知识：数值相对论、MHD模拟、数据压缩、3-D可视化和观测天文学。这个项目将产生重大的额外影响，从培训一个全新跨学科领域的研究生和博士后研究员(动态时空中的流体运动)到各种公共宣传努力。初级研究人员将需要学习先进的计算技术，包括并行计算、超大型数据集的使用和科学可视化。公共教育工作将包括常规演示，在多媒体教育程序中使用模拟动画，以及将模拟动画融入音乐和舞蹈。必要的计算发展，如计划中的积极数据压缩过程，将对探索更大动力系统的其他领域的科学家具有重要价值。

Super-massive black hole mergers are believed to happen with significant frequency, but direct detection through gravitational wave observations remains only a hope for the future. An alternate path toward finding them lies through photon observations of their effects on nearby gas, but little is known for certain about what sorts of light might be produced. To solve this problem, this project is a systematic theoretical study of the electromagnetic output from these events, from the precursor stage of binary black holes, through the event itself, and including the post-merger relaxation phase. Because the quantity and character of the light radiated depends in a fundamental way on how much mass is brought to a given distance from the black holes, coordination between the initial evolution of the system, when the binary separation is large and Newtonian dynamics applies, and the merger itself, when general relativity controls the system, is an essential part of the plan. By enabling conventional telescopic observation of these systems, the aim is to create an entirely new subfield - the astronomy of black hole mergers.These science goals can be reached only by the construction of a highly-sophisticated computational system. High-performance computation is essential because tracking the dynamics of these events involves simultaneously solving the equations of radiation transport and magneto-hydrodynamics (MHD) in a general relativistic spacetime, as well as the highly nonlinear Einstein Field Equations. Data communication requirements are also extremely challenging because even defining the dynamical spacetime of a black hole merger can require as much as several petabytes. This effort is therefore strongly multidisciplinary because of the multiple kinds of expertise needed: numerical relativity, MHD simulation, data compression, 3-d visualization, and observational astronomy.This project will have significant additional impact, ranging from training graduate students and post-doctoral fellows in a brand-new interdisciplinary field (fluid motion in dynamical spacetime) to a variety of public outreach efforts. The junior researchers will need to learn advanced computational techniques, including parallel computing, the use of very large data sets, and scientific visualization. Public education efforts will include conventional presentations, the use of simulation animations in multi-media educational programs, and integration of simulation animations into music and dance. The necessary computational developments, such as the planned aggressive data compression procedure, will be of great value to scientists in other fields exploring ever larger dynamical systems.