权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Superbursts: Multi-dimensional Simulations of Deep Carbon Explosions on Neutron Stars

超级爆发：中子星深部碳爆炸的多维模拟

基本信息

批准号：
1812838
负责人：
Edward Brown
金额：
$ 27.07万
依托单位：
Michigan State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-15 至 2022-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1812838&HistoricalAwards=false
关键词：
Superbursts Multi dimensional Simulations Deep

项目摘要

Neutron stars (NS) are the densest objects in the universe, other than black holes, and have fascinated theorists and observers since they were first conjectured. Despite a wealth of observations across the electromagnetic spectrum over the last four decades, much of what happens in the deep interior of NS remains inscrutable. Knowledge of neutron star physics is growing rapidly, due to X-ray telescopes in space, laboratory nuclear experiments, and gravitational wave detectors such as the Laser Interferometer Gravitational Wave Observatory (LIGO). A research group at Michigan State University will help astronomers to better understand neutron stars by modeling the thermally unstable ignition of carbon on the NS surface and the resulting explosion (a "superburst") using a state-of-the-art multidimensional hydrodynamics computer code. The models can reveal conditions in the outer layer of neutron stars, and help answer some critical science questions identified in National Academy reports: what is the nature of matter at exceedingly high density and temperature?, and what controls the mass, radius, and spin of compact stellar remnants? The planned work includes activities to recruit the next generation of scientists and to inform the public, who ultimately support the scientific endeavor. The group will develop educational resources to make it easier to use open-source computer simulations to explore stellar physics and incorporate discoveries made during the award into public talks at Michigan State's Abrams Planetarium.Neutron stars are unique natural laboratories to study quantum chromodynamics at finite density and low temperature. A number of recent observational, theoretical, and experimental developments have raised new questions about the internal constitution of neutron stars. For low-mass X-ray binaries, in which the neutron star accretes hydrogen- or helium-rich material, X-ray observations of accretion-induced phenomena over timescales ranging from seconds to decades provide important information about different layers of the neutron star. During accretion, runaway thermonuclear burning of the accreted material is observable as a Type I X-ray burst. The thousands of X-ray bursts and the rarer and more energetic superbursts encode information about the physics of dense matter and the workings of the accretion disk and boundary layer. The researchers will use ignition models that account for relevant heating and cooling processes in the neutron star crust. The simulations will yield testable predictions for both the precursor burst observed from some sources and the evolution of luminosity with time during the superburst. The models will inform astronomers about conditions in the outer layer of neutron stars, and may give information about the explosion's effect on the accretion flow and the nature of nuclear flames in dense matter.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.

中子星（NS）是宇宙中除黑洞之外的最重要的天体，自从它们被发现以来就一直吸引着理论家和观测者。尽管在过去的四十年里对电磁频谱进行了大量的观测，但NS内部深处发生的许多事情仍然是不可理解的。中子星星物理学的知识正在迅速增长，这要归功于太空中的X射线望远镜、实验室核实验和引力波探测器，如激光干涉引力波天文台（LIGO）。密歇根州立大学的一个研究小组将帮助天文学家更好地了解中子星，方法是使用最先进的多维流体动力学计算机代码模拟NS表面碳的热不稳定点火和由此产生的爆炸（“超级爆发”）。这些模型可以揭示中子星外层的状况，并帮助回答国家科学院报告中确定的一些关键科学问题：在极高密度和温度下物质的性质是什么？是什么控制着致密恒星残骸的质量、半径和自旋？计划的工作包括招募下一代科学家和向公众宣传的活动，公众最终支持科学奋进。该小组将开发教育资源，使其更容易使用开源计算机模拟来探索恒星物理，并将获奖期间的发现纳入密歇根州立大学艾布拉姆斯天文馆的公开讲座。中子星是研究有限密度和低温下量子色动力学的独特天然实验室。最近的一些观测、理论和实验的发展对中子星的内部构成提出了新的问题。对于低质量的X射线双星，其中中子星星吸积富含氢或氦的物质，在从几秒到几十年的时间尺度上对吸积诱导现象的X射线观测提供了关于中子星星不同层的重要信息。在吸积过程中，被吸积物质的失控热核燃烧可以观察到I型X射线爆发。数以千计的X射线爆发和更罕见、更有活力的超级爆发编码了关于致密物质物理学和吸积盘和边界层工作的信息。研究人员将使用点火模型来解释中子星星外壳中相关的加热和冷却过程。模拟将产生可检验的预测，从一些来源观察到的前兆爆发和亮度随时间的演变在超级爆发。该模型将告知天文学家关于中子星外层的条件，并可能提供有关爆炸对吸积流的影响以及致密物质中核火焰性质的信息。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。