Collaborative Research: Photons from Binary Black Hole Inspirals

每个大星系的中心都有一个超大质量黑洞。 星系会不时地合并，因此人们预计，但尚未证明，最近合并的星系拥有两个大黑洞，它们最终形成一个绑定对，然后合并。一般认为，超大质量黑洞双星通常可以积累相当数量的气体，因此在合并之前和合并期间以及之后的弛豫期都有相当长的时间是明亮的。 然而，由于估计在整个宇宙中每年只有很少的合并，因此需要了解要搜索的特定特征才能发现它们。来自罗切斯特理工学院（RIT）、约翰霍普金斯大学（JHU）和塔尔萨大学（TU）的一组研究人员和研究生提议使用蓝色沃茨超级计算机对超大质量双黑洞周围的气体进行首次真实模拟。 这些模拟将提供超大质量黑洞合并所发出的光和时间信号的预测，以便观测发现它们。该项目的重点是使用大规模数值模拟来确定识别超大质量黑洞合并过程的特征，这些模拟假设了与天体物理学相关的初始条件，并包括所有主要的相关物理：磁流体力学、广义相对论和辐射传输。 这些模拟在计算上极具挑战性，因为所涉及的物理复杂性。然而，该项目引入了两个重要的计算创新：一个依赖于时间的高阶后牛顿时空来代替爱因斯坦场方程的显式解，以及一个多面体方案来协调不同网格要求的区域的单独处理。 除了模拟活动，该项目预计将创造机会，将许多现有的研究计划整合到一个更大的科学家，学生和公众的社区。它将促进RIT，JHU和TU的本科生，研究生，博士后研究人员和教师之间的跨学科合作。通过这个网络，以前非常成功的外展计划将能够接触到更大，更多样化的受众，并将为学生提供更多的机会，与他们的家庭机构以外的研究人员进行互动和合作。它还将导致教育的研究生和博士后在非常大规模的计算技术，这将是他们未来的职业生涯的重要技能。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Every large galaxy contains a supermassive black hole in its center. Galaxies merge from time to time, therefore it is expected, but not yet demonstrated, that recently merged galaxies hold two large black holes, which eventually form a bound pair and later merge. It is generally expected that supermassive black hole binaries can often accumulate sizable quantities of gas, and therefore be bright for a significant time before and during the merge, as well as the relaxation period there after. However, because it is estimated that there are only very few such mergers per year in the entire Universe, understanding the specific features to search for is required to discover them. A team of researchers and graduate students from the Rochester Institute of Technology (RIT), Johns Hopkins University (JHU), and the University of Tulsa (TU) propose to use the Blue Waters supercomputer to perform the first realistic simulations of gas surrounding supermassive binary black holes on route to merger. These simulations will provide predictions of light and timing signatures emitted by supermassive black hole mergers in order to allow for their observational discovery.The focus of this project is to define the features that identify the process of supermassive black hole mergers, using large-scale numerical simulations that assume astrophysically relevant initial conditions and include all the principal relevant physics: magnetohydrodynamics, general relativity, and radiation transfer. These simulations are extremely challenging computationally because of the complexity of the physics involved. However, the project introduces two significant computation innovations: a time-dependent high-order post-Newtonian spacetime to substitute for explicit solution of the Einstein Field Equations and a multipatch scheme to coordinate separate treatment of regions with contrasting grid requirements. In addition to the simulation activities, the project is expected to create opportunities to integrate many existing research programs into a larger community of scientists, students, and the general public. It will foster cross-disciplinary collaboration among undergraduate students, graduate students, postdoctoral researchers and faculty at RIT, JHU and TU. Through this network, previous highly successful outreach programs will be able to reach an even larger and more diverse audience, and will provide many more opportunities for students to interact and collaborate with researchers outside their home institutions. It will also result in educating a number of graduate students and post-docs in the techniques of very large-scale computation, which will be important skills for their future careers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.