Dynamical, Strong-Field Gravity

该奖项的研究目标集中在理解爱因斯坦广义相对论的强场制度。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。这对于引力波天文学的新兴领域至关重要，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。一个例子是接近爱因斯坦理论允许的最大自转速度的黑洞的行为：有人提出，这种黑洞的视界可能会表现出某种形式的湍流动力学，而这个奖项的目标之一就是调查这些说法。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。将进行的引力波源建模项目的具体清单是(1)使用在二元黑洞合并之后剩余黑洞的准正常环状的性质来测试广义相对论，特别是黑洞的独特性，(2)使用黑洞合并观测来约束某些修改的引力理论，(3)开发替代黑洞的奇异致密物体的模型，以允许具体预测它们的合并波形如何不同于双黑洞的合并波形，并因此检测，限制或排除这样的模型，以及(4)对含有中子星的双星合并中的潮汐和耗散效应进行建模。为了解决近极克尔黑洞中的湍流问题，该小组将继续开发分析和数值工具，以研究此类黑洞在微扰理论中的二阶扰动；这一结果将指导是否需要开发适合于该问题的完整数值代码。该奖项反映了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。

The research goals of this award 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 the numerical simulation of binary black hole, black hole-neutron star and binary neutron star collisions. This is critical for 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 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 behavior of black holes that rotate close to the maximum rate theoretically allowed by Einstein's theory : there have been suggestions that the horizons of such black holes could exhibit some form of turbulent dynamics, and one goal of this award is to investigate those claims. 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) using properties of the quasi-normal ringdown of the remnant black hole following a binary black hole merger to test general relativity, in particular the uniqueness properties of black holes, (2) constraining certain modified gravity theories using black hole merger observations, (3) developing models of exotic compact object alternatives to black holes to allow concrete predictions of how their merger waveforms differ from those of binary black holes, and hence detect, constrain or rule out such models, and (4) modeling tidal and dissipative effects in the merger of binaries containing neutron stars. To address the problem of turbulence in near-extremal Kerr black holes, the group will continue development of analytical and numerical tools to study perturbations of such black holes to second order in perturbation theory; the outcome of this will guide whether a full numerical code adapted to the problem warrants development.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.