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CAREER: The Composition of Dense Matter and Observations of Neutron Stars

职业：稠密物质的组成和中子星的观测

基本信息

批准号：
1554876
负责人：
Andrew Steiner
金额：
$ 42.5万
依托单位：
University of Tennessee Knoxville
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-01 至 2022-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1554876&HistoricalAwards=false
关键词：
CAREER Composition Dense Matter Observations

项目摘要

Stars with masses greater than eight times the mass of the sun end their lives in an explosion called a core-collapse supernova. If the original star is between eight and twenty times the mass of the sun, the supernova leaves behind a neutron star. Neutron stars are ultra-dense objects with the mass of the sun and a diameter of about 15 miles. Normal matter is made of atoms consisting of electrons and nuclei, nuclei are made of neutrons and protons, and neutrons and protons, in turn, are made of up and down quarks. The gravitational force in the center of a neutron star, however, is sufficient to compress neutrons and protons together so tightly that neutrons and protons may be forced to convert into exotic particles containing strange quarks. The question of whether or not strange quarks are present in neutron stars, and the more general question of the nature of extremely dense matter, are some of the principal questions facing the nuclear physics and astrophysics communities. This project aims to answer these questions and to determine the nature of matter in the center of neutron stars where gravity compresses matter to a thousand trillion times the density of water. This project involves training opportunities for students and postdoctoral fellow. Community outreach includes the education of students through the continued development of a Studio Physics course, involvement in research, and a web-based visualization of neutron stars.Nuclear experiments and observations of neutron stars have successfully generated novel constraints on the equation of state of matter at densities near and above the central densities in atomic nuclei. However, our current understanding of high-densities is limited: we do not yet know the composition of the ground state. This project uses a combination of nuclear theory matched to nuclear data and neutron star observations to determine the composition of neutron star cores. Modern models of strongly-interacting matter will be combined with new nuclear structure calculations of neutron-rich nuclei in order to construct state of the art models of the neutron star crust and core. These models, and their concomitant uncertainties, will be calibrated with nuclear data and compared with neutron star cooling, mass, and radius observations. For example, neutron star cooling data has already given indications of fast cooling arising from a large proton-to-neutron ratio. This project will study the posterior probability distribution for the proton-to-neutron ratio and several other observables that will give insights into neutron star composition. This proposal is co-funded by the Theoretical Nuclear Physics Program in the Physics Division and the Division of Astronomical Sciences at NSF.

质量大于太阳八倍的恒星在一次被称为核心塌缩超新星的爆炸中结束了它们的生命。如果原始恒星的质量是太阳的8到20倍，超新星就会留下中子星。中子星是质量相当于太阳、直径约15英里的超高密度天体。正常物质是由电子和原子核组成的原子，原子核是由中子和质子组成的，而中子和质子又是由上夸克和下夸克组成的。然而，中子星中心的引力足以将中子和质子压缩得如此紧密，以至于中子和质子可能会被迫转化为含有奇怪夸克的奇异粒子。中子星中是否存在奇怪夸克的问题，以及密度极高的物质的性质这一更为普遍的问题，是核物理学和天体物理学面临的一些主要问题。该项目旨在回答这些问题，并确定中子星中心物质的性质，在中子星中心，重力将物质压缩到水密度的1000万亿倍。该项目涉及为学生和博士后提供培训机会。社区推广活动包括通过继续开发工作室物理课程、参与研究和基于网络的中子星可视化来教育学生。核实验和对中子星的观测成功地在原子核中心密度附近和以上的密度处对物质状态方程产生了新的约束。然而，我们目前对高密度的理解是有限的：我们还不知道基态的组成。该项目使用与核数据相匹配的核理论和中子星观测相结合的方法来确定中子星核心的组成。强相互作用物质的现代模型将与富中子核的新的核结构计算相结合，以构建最先进的中子星、壳和核的模型。这些模型及其伴随的不确定性将用核数据进行校准，并与中子星冷却、质量和半径观测进行比较。例如，中子星的冷却数据已经给出了大的质子与中子比产生的快速冷却的迹象。这个项目将研究质子与中子比率的后验概率分布，以及其他几个将为中子星组成提供洞察力的观测数据。这项提议是由国家科学基金会物理部和天文科学部的理论核物理计划共同资助的。