WoU-MMA: Gravitational Wave Coupling with Inhomogeneous Plasma and Asymptotic Theory of Polarization Effects in Curved Spacetime

科学家们长期以来一直预测，时空结构中的扰动，即引力波(GWS)，可以由双星产生，并以接近光速的速度在宇宙中传播。最近，这些波被探测到，产生了2017年诺贝尔物理学奖。这一发现为研究令人着迷的天文过程打开了新的机会，到目前为止，这些天文过程还只是假想的，可能有助于我们更好地理解宇宙。一些GW已经被探测到与电磁辐射的爆发平行，引力信号和电磁信号之间的相关性可以告诉我们比引力信号本身更多的信息。为了从这些关联中推断信息，我们需要了解GW和电磁辐射是如何在GW源周围的等离子体中耦合的。这个项目的目的是开发第一个全面的理论来解决这个复杂的关联问题。该项目直接与美国国家科学基金会的“宇宙之窗：多信使天体物理时代”的宏大构想相一致，因为了解GW波如何影响等离子体对于天体物理学家解释来自GW源的电磁辐射的来源是必要的。该项目连接了等离子体物理和引力物理，一名研究生将在这两个领域的交汇处接受新的多学科领域的培训。该项目将允许严格推导关于公制和电磁振荡组合的等离子体磁化率。利用变分方法，将建立线性等离子体波与度规振荡耦合的几何光学方程。在此过程中，还将研究引力辐射产生的非线性(有质动力)力。对于度规振荡，没有引用通常的横向极化假设，因此预计GW-等离子体耦合系数的估计将得到显著改进。在探索了由此产生的色散关系之后，通过解析和使用粒子在单元中的模拟，将估计从度规振荡到等离子体的能量转移。作为一个副产品，在规定的时空中，电磁射线与零测地线的偏差(光的自旋霍尔效应)将首次被严格计算为一般度量。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。

Scientists have long predicted that disturbances in the fabric of spacetime, called gravitational waves (GWs), can be generated by binary stars and propagate across the Universe with speeds close to the speed of light. Recently, these waves have been detected, resulting in the 2017 Nobel Prize in Physics. This discovery opens new opportunities to study fascinating astronomical processes which so far have only been hypothesized, and may help us to better understand the Universe. Some GWs have been detected in parallel with bursts of electromagnetic radiation, and correlations between gravitational and electromagnetic signals can tell us even more than gravitational signals alone. To infer information from these correlations, we need to understand how GWs and electromagnetic radiation are coupled in plasmas surrounding GW sources. This project is aimed towards developing the first comprehensive theory to address this complicated correlation problem. The project is directly aligned with the goals of NSF's "Windows on the Universe: The Era of Multi-Messenger Astrophysics" Big Idea, because understanding of how GW waves affect a plasma is necessary for astrophysicists to interpret the origin of electromagnetic radiation from GW sources. The project bridges plasma physics and gravitational physics and a graduate student will be trained in the new multidisciplinary area at the intersection of these two fields.This project will allow a rigorous derivation of the plasma susceptibilities with respect to a combination of metric and electromagnetic oscillations. Using a variational approach, geometrical-optics equations for linear plasma waves coupled with metric oscillations will be formulated. In doing so, nonlinear (ponderomotive) forces produced by gravitational radiation will also be studied. The usual assumption of transverse polarization for the metric oscillations is not invoked, so it is expected that the estimates for the GW-plasma coupling coefficients will be significantly improved. After exploring the resulting dispersion relations, both analytically and by using particle-in-cell simulations, the energy transfer from metric oscillations to plasma will be estimated. As a spinoff, the deviation of electromagnetic rays from null geodesics in prescribed spacetime (the "spin Hall effect of light") will be rigorously calculated for a general metric for the first time.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.