Relativistic Gravitation and Astrophysics

自从2015年首次探测到来自合并黑洞的引力波以来，引力波科学已经成为天文学中一个新的、充满活力的分支。除了为探索开辟了新的途径，比如宇宙黑洞的起源，它还给爱因斯坦的广义相对论带来了新的考验。天文学家对超大质量黑洞附近恒星和气体运动的观测--比如银河系中心的那个黑洞--也开启了在时空扭曲极端的领域检验爱因斯坦理论的可能性，并引发了恒星如何在这些极端物体附近形成和演化的问题。然而，为了测试爱因斯坦的伟大理论，了解它对真实测量的实际预测是至关重要的。该项目继续进行一项研究计划，以提供爱因斯坦理论的抽象之美和复杂数学与现实世界之间的具体联系，在现实世界中，物理学家和天文学家进行测量。这些联系是通过以实用和可用的形式找到方程的近似但准确的解来建立的。这项研究的结果将被引力波天文台的数据专家用来使用新检测到的信号来更好地测试广义相对论，并将被天文学家用来探索广义相对论如何影响复杂系统，如绕着超大质量黑洞运行的恒星，或涉及从黑洞到系外行星的物体的三体系统。爱因斯坦的理论是一个吸引普通公众的话题，国际和平研究所将继续就与这项研究相关的主题进行公开演讲，将爱因斯坦的思想带给更广泛的社区。具体地说，这个项目将有助于地面引力波观测站，如LIGO-Virgo-Kagra网络，通过在所谓的后牛顿近似下高精度计算由另一种重要理论-爱因斯坦-以太引力预测的双星系统发出的引力波来测试广义相对论。该项目将继续扩展PI最近的工作，将爱因斯坦理论的影响纳入三体系统的动力学，例如位于银河系核心的二元黑洞系统，其中心是一个超大质量黑洞。一个具体的目标是看看对围绕银河系中心黑洞旋转的被称为SO-2的恒星的观测是否可以用来探测或限制超大质量物体周围轨道上假想的中等质量黑洞。另一个项目是在第二次后牛顿近似下研究N体系统中的一般相对论效应，目的是评估相对论效应如何影响致密恒星系统的长期稳定性。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Since the first detection of gravitational waves from merging black holes in 2015, gravitational-wave science has emerged as a new and vibrant branch of astronomy. In addition to opening new avenues for exploration, such as the origin of cosmic black holes, it has yielded new tests of Einstein’s general theory of relativity. Observations by astronomers of the motions of stars and gas near supermassive black holes, such as the one at the center of the Milky Way, have also opened the possibility of testing Einstein’s theory in realms where the warping of spacetime is extreme, and raised questions about how stars form and evolve near such extreme objects. Yet in order to test Einstein’s great theory, it is essential to know what it actually predicts for real measurements. This project continues a program of research to provide concrete links between the abstract beauty and complex mathematics of Einstein’s theory and the real world where measurements are made by physicists and astronomers. These links are established by finding approximate, yet accurate solutions of the equations in forms that are practical and usable. The outcomes of this research will be used by data experts at the gravitational-wave observatories to perform better tests of general relativity using newly detected signals, and will be used by astronomers to probe how general relativity affects complex systems such as stars orbiting supermassive black holes, or three-body systems involving bodies ranging from black holes to exoplanets. Einstein's theory is a topic that fascinates the general public, and the PI will continue to give public lectures on topics related to this research, bringing understanding of Einstein's ideas to the broader community.Specifically, this project will contribute to the ability of ground-based gravitational-wave observatories such as the LIGO-Virgo-Kagra network to test general relativity, by computing the gravitational waves emitted by binary systems as predicted by an important alternative theory, known as Einstein-Aether gravity, to high accuracy in the so-called post-Newtonian approximation. The project will continue to extend recent work of the PI on incorporating the effects of Einstein’s theory into the dynamics of three-body systems, such as a binary-black-hole system in a galactic core with a supermassive black hole at its center. A specific goal is to see whether observations of the star known as SO-2 which revolves around the galactic center black hole can be used to detect or limit a hypothetical intermediate-mass black hole in orbit around the supermassive object. Another project is to study general relativistic effects in N-body systems at the second-post-Newtonian approximation, with the goal of assessing how relativistic effects impact the long-term stability of dense stellar systems.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.