WoU-MMA: Multimessenger Parameter Estimation for Binary Neutron Star Mergers

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。2017年8月，NSF资助的LIGO及其合作天文台探测到了来自一颗双星中子星星合并的引力波和光子，开启了多信使天文学的时代。从那时起，LIGO已经探测到了更多的双中子星星系统，预计未来还会有更多。这些发现开始彻底改变我们对高能天体物理学现象的理解，例如短伽马射线爆发，极端条件下物质的性质，以及重元素的起源，例如金和铂。然而，要取得根本性的进展，观测需要得到理论理解的补充。该项目旨在建立一个管道，用于联合分析中子星星合并的多信使观测中的不同信使。为此，将把数据分析技术和中子星星合并的大型超级计算机模拟结合起来。该项目将构成宾夕法尼亚州立大学一名研究生的博士论文的大部分，他将获得学术和行业就业市场高需求的技能。为这些模拟开发的数值方法也可以在其他STEM领域中找到应用。中子星星和黑洞时空的数值模拟也将用于创建一个沉浸式和交互式的虚拟现实探索馆，用于课堂教学和外展的紧凑对象。最常见的多信使观测中子星星合并预计将结合联合收割机引力波和紫外/光学/红外光子产生的放射性副产品的核合成过程衰变。这就是所谓的kilonova。该项目将提供基于第一原理模拟的改进的引力波和kilonova模型，并将其用于联合贝叶斯参数估计管道。将在完全广义相对论中进行多轨道高分辨率螺旋和合并模拟，使用基于熵粘性方法的新开发的高阶数值技术，提供下至后牛顿状态和上至千赫兹状态的收敛引力波应变数据，在千赫兹状态下，目前的模型开始失效。数值相关性数据将被用来构建新的频域唯象波形模型，适合贝叶斯参数估计。长期合并和合并后的模拟与微物理和次网格湍流模型将进行预测的质量和数量的流出，最终权力的kilonovae作为二元参数的函数，如总质量，潮汐变形能力，特别是，二元质量比。数值数据将结合半解析kilonova模型校准对全辐射传输计算构建一个模型的kilonova排放的二元参数的函数。Kilonova和新的引力波模型将最终结合起来，进行中子星星合并事件的联合参数估计分析。该奖项反映了NSF的法定使命，并已被认为是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的支持。

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 of gravitational waves and photons from a binary neutron star merger by NSF-funded LIGO and partner observatories in August 2017 ushered in the era of multimessenger astronomy. Since then LIGO has detected a few more binary neutron star systems and many more are expected in the future. These discoveries are starting to revolutionize our understanding of, among others, high energy astrophysics phenomena, such as short gamma-ray bursts, the properties of matter under extreme conditions, and the origin of heavy elements, such as gold and platinum. However, to make fundamental progress observations need to be complemented by theoretical understanding. This project aims to build a pipeline for the joint analysis of the different messengers in multimessenger observations of neutron star mergers. To this aim, data analysis techniques and large-scale supercomputer simulations of neutron star mergers will be combined. The project will constitute the bulk of the PhD thesis of one graduate student at Penn State, who will acquire skills in high demand in the academic and industry job markets. Numerical methods developed for these simulations could also find applications in other STEM fields. Numerical simulations of neutron star and black hole spacetimes will also be used to create an immersive and interactive virtual reality exploratorium for compact objects to be used for classroom teaching and outreach.The most common multimessenger observations of neutron star mergers are expected to combine gravitational waves and UV/optical/infrared photons generated as radioactive byproducts of the nucleosynthesis process decay. This is the so-called kilonova. This project will deliver improved gravitational wave and kilonova models based on first-principle simulations and use them in the context of a joint Bayesian parameter estimation pipeline. Many-orbit high-resolution inspiral and merger simulations will be performed in full general-relativity using newly developed high-order numerical techniques based on the entropy viscosity method to deliver convergent gravitational wave strain data extending down to the post Newtonian regime and up to the kilohertz regime, where current models start to fail. The numerical relativity data will be used to construct new frequency domain phenomenological waveform models suited for Bayesian parameter estimation. Long-term merger and post-merger simulations with microphysics and subgrid turbulence models will be performed to predict the quality and quantity of the outflows that ultimately power the kilonovae as a function of the binary parameters, such as the total mass, the tidal deformability, and, in particular, the binary mass ratio. The numerical data will be combined with a semi-analytic kilonova model calibrated against full radiative transfer calculations to construct a model of the kilonova emission as a function of the binary parameters. Kilonova and new gravitational wave models will finally be combined to perform joint parameter estimation analysis of neutron star merger events.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.