RUI: Neutron Star Crusts in Multi-Messenger Astronomy: Probability Distributions of Ground State and Accreted Crusts with Rigorously Quantified Modeling Uncertainty.

宇宙中密度最大的物质包含在中子星中，中子星的质量相当于太阳，大小相当于超新星爆炸后留下的一座城市。这种物质的性质仍然是一个谜，可以揭示自然界的基本相互作用。许多尖端的天文观测站与最新的致密物质实验室实验相结合，正在收集这种最奇特的物质的数据。我们最好的模型预测，这颗恒星的外层，大约半英里厚，是固体（地壳），下面的大部分是液体。在过去的十年里，人们花费了巨大的努力来测量这颗恒星的整体特性。然而，尽管中子星的地壳会影响中子星随时间改变温度、旋转和磁场的方式，并产生诸如星震等令人兴奋的现象，但人们还没有做出类似的努力来了解恒星地壳的性质。PI将通过将地壳置于与研究地核类似的先进技术中来解决这种不平衡。PI将检查中子星出生时的外壳的物质特性，以及伴星的物质落在中子星表面后中子星最终的外壳。该项目将指导来自代表性不足群体的学生，让他们获得开展研究和发展广泛相关技能的经验。在过去的十年里，核天体物理学界一直致力于通过对系统生成的中子星状态方程（EOS）的大集合进行统计分析，从中子星质量和半径的测量中提取中子星状态方程（EOS）。在某种程度上，这是对数据质量显著提高的回应，随着一些尖端天文台和实验的出现，包括激光干涉引力波天文台（LIGO）， NASA的中子星内部成分探测器（NICER）在天文学方面，铅（Pb）半径实验（PREX）和新完成的稀有同位素束设施（FRIB）在核实验方面。寻找整个EOS只是对恒星内部特性研究的一个方面。许多观测到的现象都是中子星有一千米厚的固体外壳的直接结果。中子星的冷却、脉冲星故障等旋转异常、持续的引力波、磁场演化和星震都可能带有中子星地壳物理特性的特征。该项目将对地壳进行与恒星EOS相同的统计审查，开发地壳模型的大型集合，并应用天体物理和核数据，首次获得地壳材料特性具有良好特征的不确定性的约束，并确定当中子星从伴星吸积物质时这些特性如何变化。该项目推进了“宇宙之窗：多信使天体物理学时代”的目标，这是美国国家科学基金会未来投资的十大理念之一。该奖项反映了美国国家科学基金会的法定使命，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 densest matter in the universe is contained within neutron stars – an object with the mass of our Sun and the size of a city left behind after a supernova explosion. The properties of this matter remain a mystery and could shed light on the fundamental interactions of nature. A number of cutting edge astronomical observatories coupled with the latest in laboratory experiments on dense matter are gathering data on this most exotic of materials. Our best models predict that the outer layer of the star, about half a mile thick, is a solid (the crust), and the bulk of the star beneath is a liquid. Over the last decade, a huge effort been expended measuring the properties of the star overall. However, a similar effort has not yet been devoted to understanding the properties of the crust of the star, despite its impact on the way neutron stars change their temperature, rotation and magnetic field over time, and give rise to exciting phenomena such as starquakes. The PI will address this imbalance by subjecting the crust to similar state-of-the-art techniques as have been developed for studying the core. The PI will examine the material properties of both the crusts the neutron stars are born with, and those neutron stars end up with after matter from a companion star falls onto their surface. The PI will mentor students from underrepresented groups and give them experience conducting research and developing a wide range of associated skills. The last decade has seen the nuclear astrophysics community focus on extracting the neutron star equation-of-state (EOS) from measurements of the masses and radii of neutron stars by performing statistical analyses on large ensembles of systematically generated EOSs. In part this is a response to a marked increase in the quality of the data with the advent of a number of cutting-edge observatories and experiments including the Laser Interferometric Gravitational-wave Observatory (LIGO), NASA’s Neutron star Interior Composition ExploreR (NICER) on the astronomy side, and the Lead (Pb) Radius Experiment (PREX) and the newly completed Facility for Rare Isotope Beams (FRIB) on the nuclear experimental side. Finding the overall EOS is just one strand of research into the interior properties of the star. Many observed phenomena are a direct result of the neutron star having a solid crust about a kilometer thick. The cooling of neutron stars, rotational anomalies such as pulsar glitches, persistent gravitational waves, magnetic field evolution and starquakes could all bear the signatures of the physics of the neutron star crust. This project will subject the crust to the same statistical scrutiny as the EOS of the star, developing large ensembles of crust models and applying astrophysical and nuclear data to obtain, for the first time, constraints with well characterized uncertainty on the material properties of crusts, and determine how those properties change when a neutron star accretes material from a companion.This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments.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.