WoU-MMA: Multi-Messenger Gravitational Lensing with Asymmetric Lenses and Sources

该奖项与爱因斯坦广义相对论的三个惊人预测有关：黑洞（BH），引力波（GW）和引力透镜。当像黑洞这样的大质量紧凑物体快速相互绕轨道运行并由于它们之间巨大的引力而合并时，它们会在时空GW中产生涟漪。这些GW在地球上被探测到，就像LIGO探测器臂长的微小变化一样。黑洞的质量、自旋和轨道参数决定了观测到的GW信号的频率和振幅随时间的变化。自2015年LIGO合作首次探测以来，已经观测到90多个致密天体合并。 这为宇宙打开了一扇令人兴奋的新窗口，补充了使用望远镜捕获电磁波（EM）的观测结果，如可见光。当GW或EM波穿过宇宙时，它们可以被非常接近它们路径的大质量物体所偏转和聚焦。尽管这种强引力透镜现象尚未在GW源中被发现，但预计它会将GW信号分成多个放大的副本，每个副本都采取稍微不同的路径到达观测者。在HST或JWST图像上看到的这种强透镜过程的EM模拟是遥远的星系被前景星系团透镜拉伸成引人注目的弧形。透镜签名取决于干预透镜的重力，使其成为衡量和研究暗物质的重要工具。随着地基GW探测器灵敏度的提高和丽莎等天基探测器的出现，GW源将被看到到很远的地方，在那里干预透镜的机会是相当大的。这个奖项将增加我们对宇宙历史中黑洞的性质和引力的理解，以及暗物质在介入透镜中的分布。这将为引力波的强透镜效应提供新的理论模型。该奖项还将促进几项有益于社会的教育和推广活动，例如扩展双黑洞的交互式VIGOR（与引力波观察相对论的虚拟交互）模拟，为当地高中和本科生课程开发课程材料，以及与博物馆合作。研究生和本科生将沉浸在研究中，为学术界和工业界激励和培养下一代科学家。 未来将观测到越来越多的高红移GW事件，其中很大一部分将经历强引力透镜效应。目前大多数的研究假设在两个双黑洞（BBH）源的轨道角动量和透镜模型的光轴从观察者通过透镜轴对称。这些假设将在三个相互关联的项目中放宽。(1)极端质量比螺旋（EMRI）的透镜，其中轨道角动量通常与超大质量黑洞（SMBH）的自旋不一致，并且透镜可能被误解为偏离广义相对论。(2)更真实的透镜模型的透镜放大系数，包括嵌入SMBH在银河系中心，核心密度分布，和不对称的透镜星系或外部剪切。(3)源星系或瞬变电磁观测与GW源之间的协同作用。 同时表征GW源中的岁差和透镜效应对于它们作为天体物理学和重力探测器的使用至关重要。更真实的非对称透镜模型对于真实的数据分析也是必不可少的，因为轴对称模型在几何光学极限中定性地不能解释额外的图像，并且在大部分源平面上采用更复杂的波动光学是必不可少的。大多数BBH合并可能会缺乏瞬态EM对应物，因此需要将GW和EM调查相关联的多信使研究来识别宿主星系。该奖项反映了NSF的法定使命，并被认为值得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来支持。

This award is concerned with three spectacular predictions of Einstein’s theory of general relativity: black holes (BHs), gravitational waves (GWs) and gravitational lensing. When massive compact objects such as BHs rapidly orbit each other and merge due to the huge gravitational force between them, they create ripples in space-time – GWs. These GWs are detected on earth as tiny changes in the lengths of the arms of a detector such as LIGO. The masses, spins, and orbital parameters of the BHs determine the observed frequency and amplitude of the GW signal as a function of time. Since the first detection by the LIGO collaboration in 2015, more than 90 binary compact-object mergers have been observed. This has opened an exciting new window on the Universe that complements what is seen using telescopes that capture electromagnetic (EM) waves such as optical light. When GWs or EM waves pass through the Universe they can be deflected and focused by intervening massive objects very close to their path. Although this strong gravitational lensing phenomenon has not yet been identified for GW sources, it is expected to split GW signals into multiple magnified copies, each taking a slightly different path to the observer. An EM analog of this strong lensing process, as seen on HST or JWST images, are the distant galaxies stretched into eye-catching arcs by foreground galaxy cluster lenses. Lensing signatures depend on the gravity of the intervening lens, making it an essential tool to weigh and study dark matter. With the increasing sensitivity of ground-based GW detectors and the advent of space-based detectors like LISA, GW sources will be seen to vast distances where the chance of an intervening lens is considerable. This award will increase our understanding of the properties and gravity of BHs across cosmic history, and the distribution of dark matter in intervening lenses. It will provide new theoretical models of strong lensing of GWs. The award will also facilitate several educational and outreach activities of benefit to society, such as an extension of the interactive VIGOR (Virtual Interaction with Gravitational Waves to Observe Relativity) simulation of binary black holes, development of curriculum materials for local high schools and undergraduate classes, and engagement with museums. Graduate and undergraduate students will be immersed in the research, inspiring and training the next generation of scientists for academia and industry. Increasing numbers of high-redshift GW events will be observed in the future, and a significant fraction of these sources will experience strong gravitational lensing. Most current research assumes axisymmetry in both the binary black hole (BBH) sources about their orbital angular momentum and in the lens models about the optical axis passing from the observer through the lens. These assumptions will be relaxed in three interrelated projects. (1) Lensing of extreme-mass-ratio inspirals (EMRIs) in which the orbital angular momentum is generically misaligned with the supermassive black hole (SMBH) spin, and where lensing could be misinterpreted as deviations from general relativity. (2) Lensing amplification factors for more realistic lens models that include embedded SMBHs at galactic centers, cored density profiles, and asymmetry in either the lens galaxy or an external shear. (3) Synergies between EM observations of source galaxies or transients, and GW sources. Simultaneously characterizing precession and lensing in GW sources is critical for their use as probes of both astrophysics and gravity. More realistic asymmetric lens models are also essential for real data analysis, as axisymmetric models qualitatively fail to account for additional images in the geometric-optics limit and employing more complicated wave-optics is essential over much of the source plane. Most BBH mergers will probably lack transient EM counterparts, so multi-messenger studies correlating GW and EM surveys will be required to identify host galaxies.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.