WoU-MMA: Collaborative Research: Constraining the Nuclear Equation of State and Neutron Star Astrophysics Through Multi-messenger and Multi-object Observations of Neutron Stars

第一颗已知的合并双星中子星星（GW 170817）的革命性发现和多信使后续行动表明，对这种合并的观测和分析可以提供独特的机会。 罗切斯特理工学院和田纳西大学诺克斯维尔之间的科学合作将开发利用引力波（GW）观测和电磁观测所需的研究基础设施，以确定致密物质的性质。 研究小组将开发一种灵活的程序，直接从许多NS的多次测量中，使用GW测量合并，银河NS的X射线观测以及由此产生的kilonova爆炸的光变曲线和光谱，自洽地推断中子星（NS）的核状态方程（EOS）。 EOS是一个方程，就像物理学中的理想气体定律，它描述了在给定的一组物理条件下物质的状态。 使用衍生的工具来理解核EOS，研究人员将确定是否二元合并负责观察到的r-过程元素丰度。 快速中子俘获过程（英语：Rapid neutron capture process）是一系列的核反应，在天体物理环境中，许多比铁重的原子元素都是通过这一过程产生的。 该项目将包括培训年轻研究人员作为第一代真正的多信使天体物理学家，主要研究人员将为介绍广义相对论创建新的课程材料，以教育下一代科学家了解GW天文学的结果。 该研究计划有两个主要目标：限制致密核物质的性质，并确定是否NS合并单独解释的r-过程元素的丰度。 研究小组将为kilonova光变曲线和光谱创建新的高精度替代模型，并根据详细的辐射传输计算进行校准。为了对来自多个信使和多个对象的数据进行推断，其中每个数据源以不同的方式连接到EOS，研究人员将创建一个统一的贝叶斯推理引擎，称为Concordance。 这个推理机将限制致密的核物质和中子星星核心的组成。它还将推断NS合并率，喷出物质量和喷出物成分，这将使科学家能够预测由于观测到的NS合并的人口而在当今局部宇宙中的元素-元素r-过程丰度。他们将比较他们的预测与观测结果;确定是否需要以及需要什么样的失踪人口（如黑洞（BH）-NS）来协调观测与元素丰度;并查看失踪人口是否与形成情景和观测约束一致。 该项目推进了NSF宇宙大创意窗口的目标。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The revolutionary discovery and multi-messenger follow-up of the first known merging binary neutron star (GW170817) has demonstrated the unique opportunities that observations and analysis of such mergers can provide. A scientific collaboration between Rochester Institute of Technology and the University of Tennessee, Knoxville, will develop the research infrastructure needed to exploit gravitational wave (GW) observations and electromagnetic observations in order to determine the nature of dense matter. The research team will develop a flexible procedure to self-consistently infer the nuclear equation of state (EOS) for neutron stars (NS), directly from multiple measurements of many NS, using GW measurements of mergers, X-ray observations of galactic NS, and light curves and spectra from the resulting kilonova explosion. An EOS is an equation, like the ideal gas law of physics, which describes the state of matter under a given set of physical conditions. Using the tools derived to understand the nuclear EOS, the investigators will determine if binary mergers are responsible for the observed r-process elemental abundances. The rapid neutron-capture process (r-process) is a set of nuclear reactions by which many of the atomic elements heavier than iron are produced in astrophysical settings. The project will include the training of young researchers as the first generation of truly multi-messenger astrophysicists, and the principal investigators will create new course materials for introductory general relativity, to educate the next generation of scientists in results from GW astronomy. The research program has two major goals: to constrain the nature of dense nuclear matter and to determine whether NS mergers alone explain the abundances of r-process elements. The research team will create new high-precision surrogate models for kilonova light curves and spectra, calibrated to detailed radiative-transfer calculations. To draw inferences with data from multiple messengers and multiple objects, where each data source is connected to the EOS in a different way, the researchers will create a unified Bayesian inference engine, called Concordance. This inference engine will constrain dense nuclear matter and the composition of the neutron star core. It will also infer the NS merger rate, ejecta mass, and ejecta composition, which will allow the scientists to predict the element-by-element r-process abundances in the present-day local universe due to the observed population of binary NS mergers. They will compare their prediction to observations; determine whether and what kind of missing population (like black hole (BH)-NS) would be required to reconcile observations with element abundances; and see whether that missing population is consistent with formation scenarios and observational constraints. This project advances the goals of the NSF Windows on the Universe Big Idea.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.