WOU-MMA: Gravitational Radiation and Relativistic Astrophysics

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”大构想的优先领域。自2019年以来，NSF的激光干涉仪引力波天文台(LIGO)一直在定期探测距离地球数十亿光年的致密物体碰撞发出的引力波(GWS)(空间和时间上的涟漪)。这些天体中的大多数是黑洞，其他的是中子星。通过GWS，科学家可以测量物体的性质(位置、质量、自转)，了解它们可能是如何形成的，以及它们在碰撞时如何扭曲空间和时间；对于中子星，碰撞还会产生伽马射线和其他电磁辐射，与GWS一起，这向科学家们传授了物质在超高密度下的行为以及一些化学元素是如何形成的。但这些研究需要将探测到的GW与对海浪的详细预测进行比较。这些预测是使用爱因斯坦在1915年写下的广义相对论方程做出的，但直到2005年左右，随着先进方法和强大的超级计算机的发展，广义相对论方程才得以求解(用于碰撞致密物体)。该项目支持旨在巩固和提高LIGO从观测到的GW中提取波携带的丰富信息的能力的理论工作，并改进对LIGO事件的电磁对应解释。这包括改进和使用光谱爱因斯坦代码(SPEC)，这是目前用于求解黑洞双星爱因斯坦方程的最准确的计算机代码。SPEC将被用来进行黑洞碰撞的数值解，以进一步开发用于分析LIGO数据的GW预测的公共目录。此外，正在开发的下一代公共计算机代码SPECTE将用于预测两颗碰撞的中子星、一个黑洞与中子星碰撞的GW以及超新星爆炸的GW。该计划还将作为年轻物理学家和天体物理学家的训练场。小组成员将通过讲座、互动网页和YouTube视频向公众开放。通过将分析技术和数值模拟与光谱爱因斯坦代码(SPEC)相结合，该小组将：(I)将产生改进的双星黑洞(BBH)引力波形，用于BBH参数空间中探索不足的区域的LIGO数据分析，并将用于产生在精度、参数空间覆盖范围和包含物理(例如偏心率、引力记忆)方面得到改进的替代模型；(Ii)高度弯曲时空的动力学行为将通过解析、微扰和数值方法来探索，其中将包括对Rundown中准正常模激发和非线性的研究，以及对超越爱因斯坦引力理论的调查和使用LIGO观测对其进行测试。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。

This award supports research in relativity and relativistic astrophysics, and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. Since 2019, NSF's Laser Interferometer Gravitational-Wave Observatory (LIGO) has been regularly detecting gravitational waves (GWs) (ripples in space and time) emitted by the collision of compact objects that are billions of light-years from Earth. Most of these objects have been black holes, others have been neutron stars. From the GWs, scientists can measure properties (locations, masses, spins) of the objects and learn about how they might have formed and how they warp space and time as they collide; for neutron stars, the collision also produces gamma-rays and other electromagnetic radiation, and together with the GWs this teaches scientists how matter behaves at ultra-high densities and how some chemical elements were formed. But these studies require comparing the detected GWs with detailed predictions of the waves. The predictions are made using the equations of General Relativity, written down by Einstein in 1915 but unsolvable (for colliding compact objects) until about 2005 with the development of advanced methods and powerful supercomputers. This project supports theoretical work designed to underpin and improve LIGO's ability to extract from observed GWs the rich information that the waves carry, and to improve the interpretation of LIGO events with electromagnetic counterparts. This includes the improvement and use of the Spectral Einstein Code (SpEC), currently the most accurate computer code for solving Einstein's equations for black hole binaries. SpEC will be used to carry out numerical solutions of black-hole collisions to further develop a public catalog of GW predictions for the purpose of analyzing LIGO data. In addition, a next-generation public computer code SpECTRE, under development, will be used to predict GWs from two colliding neutron stars, from a black hole colliding with a neutron star, and from supernova explosions. This program will also serve as a training ground for young physicists and astrophysicists. The group members will reach out to the general public through lectures, interactive web pages, and YouTube videos.By combining analytical techniques and numerical simulations with the Spectral Einstein Code (SpEC), the team will: (i) improved gravitational waveforms for Binary Black Holes (BBH) will be generated for use in LIGO data analysis in poorly-explored regions of the BBH parameter space, and will be used to produce surrogate models that are improved in accuracy, parameter-space coverage, and included physics (e.g. eccentricity, gravitational memory); and (ii) the dynamical behavior of highly curved spacetime will be explored via analytic, perturbative, and numerical approaches, which will include studies of quasinormal mode excitations and nonlinearities in ringdowns, and investigations of beyond-Einstein theories of gravitation and testing them using LIGO observations.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.