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

已知的第一颗合并双中子星(GW170817)的革命性发现和多信使后续行动表明，对这种合并的观察和分析可以提供独特的机会。罗切斯特理工学院和诺克斯维尔田纳西大学之间的一项科学合作将开发所需的研究基础设施，以利用引力波(GW)观测和电磁观测来确定稠密物质的性质。研究小组将开发一种灵活的程序，直接根据对许多中子星的多次测量，使用合并的GW测量、星系NS的X射线观测以及由此产生的千诺瓦爆炸的光曲线和光谱，自洽地推断中子星(NS)的核状态方程(EOS)。状态方程是一个方程，就像物理中的理想气体定律一样，它描述了物质在给定的一组物理条件下的状态。使用所得的工具来理解核状态方程，研究人员将确定二元合并是否对观察到的r过程元素丰度负责。快速中子俘获过程(r过程)是一组核反应，许多比铁重的原子元素是在天体物理环境中产生的。该项目将包括将年轻研究人员培训为第一代真正的多信使天体物理学家，主要研究人员将编写新的广义相对论入门课程材料，以教育下一代科学家了解全球天文学的结果。该研究计划有两个主要目标：限制致密核物质的性质，以及确定NS合并是否单独解释了r过程元素的丰度。研究小组将为千诺瓦光曲线和光谱创建新的高精度替代模型，并对其进行校准，以进行详细的辐射传输计算。为了从来自多个信使和多个对象的数据中得出推断，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Concorance。这个推理机将约束致密的核物质和中子星核心的成分。它还将推断NS合并率、喷出物质量和喷出物组成，这将使科学家能够根据观察到的双星NS合并的群体，预测当今局部宇宙中逐个元素的r过程丰度。他们将把他们的预测与观测进行比较；确定是否以及需要什么样的缺失种群(如黑洞(BH)-NS)来使观测与元素丰度相一致；并查看缺失种群是否与形成情景和观测限制一致。这个项目推进了NSF宇宙大理想之窗的目标。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。

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.