Relativistic Gravitation and Astrophysics

最近美国LIGO天文台对引力波的探测，展示了一种利用时空涟漪“聆听”宇宙的新方法，并为爱因斯坦的广义相对论提供了令人惊叹的新检验。 天文学家对超大质量黑洞（如银河系中心的黑洞）附近恒星和气体运动的观测，开启了在时空弯曲极端的领域测试爱因斯坦理论的可能性。 然而，为了检验爱因斯坦的伟大理论，必须知道它对真实的测量的实际预测。 这个项目继续一项研究计划，以提供爱因斯坦理论的抽象美和复杂数学与物理学家和天文学家进行测量的真实的世界之间的具体联系。 这些联系是通过找到近似的，但在实际和可用的形式方程的精确解。 在这项研究中开发的解决方案将被引力波观测站的数据专家用来使用新检测到的信号对广义相对论进行更好的测试，并将被天文学家用来探测大质量黑洞附近的扭曲时空如何影响围绕这些物体运行的恒星。 爱因斯坦的理论是一个令公众着迷的话题，PI将继续就与此研究相关的主题进行公开讲座，让更广泛的社区了解爱因斯坦的思想。具体来说，该项目将有助于提高LIGO-Virgo网络等地面引力波观测站验证广义相对论的能力，通过计算二元星星系统的运动方程，沿着发出的引力波形，正如一个重要的替代理论所预测的那样，称为标量张量引力，在所谓的后牛顿近似中具有高精度。 它将以一种可以适应LIGO-Virgo数据分析方法的格式提供由该理论预测的准确波形。 该方法扩展了PI及其合作者多年来开发的称为松弛爱因斯坦方程直接积分的方法。 PI在2008年提出的使用未来的红外望远镜在我们银河系中心的大质量黑洞附近测试广义相对论的可能性将进一步研究。 将使用基于后牛顿近似的分析手段研究广义相对论对大质量黑洞周围星团的结构和长期演化的影响。

The recent detections of gravitational waves by the LIGO observatories in the USA have demonstrated a new way of "hearing" the universe using ripples in spacetime, and have provided stunning new tests of Einstein's theory of general 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 opened the possibility of testing Einstein's theory in realms where the warping of spacetime is extreme. 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 solutions developed in 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 the warped spacetime near massive black holes affects stars orbiting such objects. 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 network to test general relativity, by computing the equations of motion for binary star systems, along with the emitted gravitational waveforms, as predicted by an important alternative theory, known as scalar-tensor gravity, to high accuracy in the so-called post-Newtonian approximation. It will provide accurate waveforms predicted by this theory in a format that can be adapted to LIGO-Virgo data analysis methods. The approach extends a method known as Direct Integration of the Relaxed Einstein Equations that has been developed over many years by the PI and his collaborators. The possibility of testing general relativity in the vicinity of the massive black hole in the center of our galaxy using future infrared telescopes, proposed by the PI in 2008, will be investigated further. The effects of general relativity on the structure and long-term evolution of clusters of stars around massive black holes will be studied using analytic means based on the post-Newtonian approximation.