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，并解决了NSF“宇宙之窗”大理念的优先领域。自2019年以来，NSF的激光干涉引力波天文台（LIGO）一直在定期探测距离地球数十亿光年的紧凑物体碰撞发出的引力波（GW）（空间和时间的涟漪）。这些物体大多数是黑洞，其他的是中子星。从GWs，科学家可以测量物体的属性（位置，质量，自旋），并了解它们如何形成以及它们如何在碰撞时扭曲空间和时间;对于中子星，碰撞还产生伽马射线和其他电磁辐射，与GWs一起，这告诉科学家物质如何在超高密度下表现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与对波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，这些方程才得以解决（对于碰撞的紧凑物体）。该项目支持旨在支持和提高LIGO从观测到的GWs中提取波携带的丰富信息的能力的理论工作，并改进LIGO事件与电磁对应物的解释。 这包括改进和使用光谱爱因斯坦代码（SpEC），目前最准确的计算机代码解决爱因斯坦方程的黑洞二进制。SpEC将用于进行黑洞碰撞的数值解，以进一步开发GW预测的公共目录，用于分析LIGO数据。 此外，正在开发中的下一代公共计算机代码SpECTRE将用于预测两颗碰撞中子星、黑洞与中子星星碰撞以及超新星爆炸的引力波。 该计划还将作为年轻物理学家和天体物理学家的培训基地。小组成员将通过讲座、互动网页和YouTube视频与公众接触。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，小组将：（i）将生成改进的二元黑洞（BBH）引力波形，用于BBH参数空间探索不足区域的LIGO数据分析，并将用于生成在精度、参数空间覆盖范围和物理特性方面都有所改进的替代模型（例如偏心率、重力记忆）;以及（ii）高度弯曲时空的动力学行为将通过分析，微扰和数值方法进行探索，这将包括准正规模式激励和振铃中的非线性的研究，和超越的调查-爱因斯坦引力理论，并使用LIGO观测对其进行测试。该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响评审标准。

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.