Dynamical, Strong-Field Gravity

该奖项支持相对论和相对论天体物理学的研究，并阐述了美国国家科学基金会“宇宙之窗”宏伟构想的优先领域。该项目的研究目标是了解爱因斯坦广义相对论的强场机制。这包括天体物理学和广义相对论的理论两个方面。在天体物理方面，主要工作是双星黑洞、黑洞-中子星和双星中子星碰撞的数值模拟。这对于支持新生的引力波天文学领域很重要，该领域始于2015年LIGO探测到两个黑洞的碰撞。该磁场的推进速度也令人叹为观止，2017年首次探测到双中子星碰撞的引力波，同时大量观测天文学家对电磁频谱的后果进行了紧张的研究。这类事件的数字模型对于帮助探测是必要的，而且对于破译所发生事件的细节至关重要。在理论方面，关于极端情况下时空的性质有许多悬而未决的问题。一个例子是爱因斯坦的理论预测的发生在黑洞内部深处的奇点的性质。尽管广义相对论被认为是不可观测的，因为没有任何信息可以从黑洞中逃脱，但广义相对论如何在黑洞中崩溃仍然是一个极具理论意义的问题，因为它将提供线索，说明假定的量子引力理论需要完成什么才能解决经典奇点。这些项目的实施将涉及研究生、本科生和博士后研究员。他们将接受培训，从事领先的科学研究，在相应的物理领域变得知识渊博，并熟练掌握高性能计算和数值方法。将进行的引力波源模拟项目的具体清单包括：(1)了解双星中子星和黑洞-中子星合并中中子星自转的后果，(2)开发检测具有高轨道偏心率的合并的方法，(3)使用双星黑洞碰撞中残余黑洞的准正常环状特性来测试广义相对论，特别是黑洞的独特性，(4)在某些修正的引力理论中开发合并模型，以更好地理解观测如何排除这种修正的假设，或者如何发现广义相对论以外的新物理。对于黑洞内部，首要问题将是研究在三维渐近反De-Sitter时空中引力崩塌时形成的旋转BTZ(Banados-Teitelboim-Zanelli)黑洞的性质。与在四维时空中形成克尔黑洞相比，这提供了一个简化的场景，这是这一研究路线的最终目标。这一奖项反映了美国国家科学基金会的法定使命，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。

This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. The research goals of this project are focused on understanding the strong-field regime of Einstein's theory of general relativity. This encompasses both astrophysical and theoretical aspects of general relativity. On the astrophysical side, the main effort is numerical simulation of binary black hole, black hole-neutron star and binary neutron star collisions. This is important to support the nascent field of gravitational wave astronomy that began in 2015 with LIGO's detection of the collision of two black holes. The speed at which the field is advancing is also breathtaking, with the first gravitational wave detection of a binary neutron star collision in 2017, accompanied by intense study of the aftermath across the electromagnetic spectrum by a large community of observational astronomers. Numerical models of such events are needed to aid in detection, and are crucial to decipher details of what happened. On the theoretical side, there are many outstanding questions about the nature of spacetime in extreme situations. One example is the nature of singularities predicted by Einstein's theory to occur deep in the interior of black holes. Though not thought to be observable as no information can escape from black holes, how general relativity breaks down here is still of keen theoretical interest, as it will give clues to what a putative theory of quantum gravity needs to accomplish to resolve classical singularities. The pursuit of these projects will involve graduate students, undergraduates and postdoctoral fellows. They will be trained to do leading scientific research, become knowledgeable in corresponding areas of physics, and adept in high-performance computing and numerical methods. These skills are invaluable to many professions, and would thus also benefit and further the development of those students and postdocs that subsequently wish to pursue careers outside academia.A specific list of gravitational wave source modeling projects that will be pursued are (1) understanding the consequences of neutron star spin in binary neutron star and black hole-neutron star mergers, (2) developing methods to detect mergers that occur with high orbital eccentricity, (3) using properties of the quasi-normal ringdown of the remnant black holes in binary black hole collisions to test general relativity, in particular the uniqueness properties of black holes, (4) developing models of mergers in certain modified gravity theories to better understand how observations can either rule out such modified scenarios, or detect novel physics beyond general relativity. Regarding black hole interiors, the initial problem will be to study the nature of rotating BTZ (Banados-Teitelboim-Zanelli) black holes formed during gravitational collapse in 3-dimensional asymptotically Anti de-Sitter spacetime. This offers a simplified scenario compared to forming Kerr black holes in four-dimensional spacetime, the ultimate goal of this line of research.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.