Theoretical Studies in Gravitation and Astrophysics

该奖项支持相对论和相对论天体物理学的研究，并涉及美国国家科学基金会“宇宙之窗”大创意的优先领域。 LIGO/Virgo Scientific Collaboration 对双黑洞 (BHBH) 合并、双中子星 (NSNS) 合并和几个可能的黑洞-中子星 (BHNS) 合并产生的引力波 (GW) 事件的探测为宇宙打开了一扇新的窗口，可以帮助我们了解最极端条件下的物质物理学，这是传统手段不可能实现的。引力波、电磁（EM）和中微子辐射的联合探测有望解决许多长期存在的天体物理难题，例如短伽马射线爆发（sGRB）和r过程元素的起源，以及超核密度下物质的性质。多信使天体物理学需要对各种结构的致密天体的物理学有全面的了解。该项目将解决几个不同的问题，其共同特征是物质在动态、强引力状态下极端条件下的行为，并将涉及广义相对论、相对论流体动力学和磁流体动力学，以及电磁和中微子输运。 这些主题中的大多数都代表了理论物理中长期存在的基本问题，需要大规模计算才能解决。因此，除了分析建模之外，该计划还涉及超级计算机上的大量大规模模拟。 PI 制作的模拟电影将继续用作本科生培训工具。 这笔赠款支持的研究和推广活动有助于促进计算机和可视化工具在各级教育中的使用，以及公众对引力物理和天体物理学的一些最新和最令人兴奋的发展的认识。 在这些领域接受培训的年轻研究人员将获得超出天体物理学范围、在众多应用领域有用的技能，因此他们的需求量很大。为了了解当前和未来的观测结果，特别是强重力、电磁和潜在的微观物理之间的相互作用，将它们与理论模型的预测进行比较至关重要。要解决的问题包括初始值和演化计算，并将处理包含沉浸在气体环境中的黑洞的时空，以及包含具有磁场以及电磁和中微子辐射的中子星的时空。 一些研究主题包括致密双星（BHBH、NSNS 和 BHNS）的吸入和合并；通过合并双星和其他有前景的天体物理源及其对应的电磁信号产生引力波；重力塌陷；磁化旋转相对论恒星的稳定性以及不稳定恒星的演化和最终命运；伽马射线爆发源；超大质量恒星磁旋转塌缩和其他情况导致的超大质量黑洞（SMBH）的形成和生长；星系和类星体核心中合并双星超大质量黑洞周围的环双星盘；包括银河系在内的星系核心超大质量黑洞周围暗物质的轮廓和可观测特征，以及包含暗物质、恒星和超大质量黑洞的星团的动态演化。这些结果对天文观测具有重要意义，包括由引力波干涉仪收集和/或计划使用的天文观测。该奖项反映了 NSF 的法定使命，并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，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 detection by LIGO/Virgo Scientific Collaboration of gravitational wave (GW) events from binary black hole (BHBH) mergers, binary neutron star (NSNS) mergers and several likely black hole-neutron star (BHNS) mergers opened a new window in the Universe that can help us understand the physics of matter under the most extreme conditions, something impossible by traditional means. The combined detection of GW, electromagnetic (EM) as well as neutrino radiation promises to resolve a number of long-standing astrophysical puzzles, such as the origin of short gamma-ray bursts (sGRBs) and r-process elements, as well as the nature of matter at supranuclear densities. Multimessenger astrophysics requires a comprehensive understanding of the physics of compact objects in a variety of configurations. The project will address several different problems whose common feature is the behavior of matter under extreme conditions in a dynamical, strongly gravitating regime and will involve General Relativity, relativistic hydrodynamics and magnetohydrodynamics, as well as EM and neutrino transport. Most of these topics represent long-standing, fundamental problems in theoretical physics requiring large-scale computation for a solution. Hence this program involves a significant degree of large-scale simulations on supercomputers, in addition to analytical modeling. Movies of the simulations produced by the PIs will continue to be used as an undergraduate training vehicle. The research and outreach activities supported by this grant help promote the use of computers and visualization tools at all levels of education, as well as public awareness of some the latest and most exciting developments in gravitational physics and astrophysics. Young researchers trained in these areas will acquire skills that are useful beyond the scope of astrophysics in a plethora of applied domains, and hence they will be in great demand. To understand the current and future observations and, in particular, the interplay between strong gravity, EM, and the underlying microphysics, it is crucial to compare them to predictions from theoretical modeling. The problems to be tackled comprise both initial value and evolution computations and will treat spacetimes containing black holes immersed in gaseous environments, as well as spacetimes containing neutron stars with magnetic fields and both EM and neutrino radiation. Some of the topics for investigation include the inspiral and coalescence of compact binaries (BHBHs, NSNSs and BHNSs); the generation of GWs from merging binaries and other promising astrophysical sources, and their counterpart EM signals; gravitational collapse; the stability of magnetized rotating, relativistic stars and the evolution and final fate of unstable stars; gamma-ray burst sources; the formation and growth of supermassive black holes (SMBHs) from the magnetorotational collapse of supermassive stars and other scenarios; circumbinary disks around merging binary SMBHs in the cores of galaxies and quasars; and the profiles and observable signatures of dark matter around SMBHs in galaxy cores, including the Milky Way, and the dynamical evolution of clusters containing dark matter, stars and SMBHs. The results have important implications for astronomical observations, including those collected by and/or planned for GW interferometers.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.