Collaborative Research: WoU-MMA: Coherent radio and x-ray precursor transients to gravitational wave events: Simulations in general relativity and kinetic theory

合作研究：WoU-MMA：引力波事件的相干射电和 X 射线前兆瞬变：广义相对论和动力学理论的模拟

• 批准号: 2307395
• 负责人: Alexander Philippov
• 金额: $ 37.5万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307395&HistoricalAwards=false
• 关键词: Collaborative; Research; WoU; MMA; Coherent

A central issue in astrophysics today is understanding the merging of neutron stars (NS), highly compact celestial objects, or NS with black holes (BH). Such mergers produce gravitational waves (GW), a counterpart electromagnetic signal, and ultimately the heaviest atomic elements in the universe. In addition to counterparts produced during and after the merger of such systems, it might also be possible to create prompt transient events before the collision, due to the presence of strong magnetic fields in the inspiraling NS. Such a precursor event was recently reported for the long gamma-ray burst GRB 211211A. Understanding whether and how such transients can be launched will be crucial both as an additional tool for prompt sky localization by aiding follow-up searches for GW afterglows, as well as constraining currently inaccessible parameters such as the magnetic field strengths in the pre-merger system. A research collaboration between California Institute of Technology and the University of Maryland, College Park, will investigate these issues through a program of computer simulations in general relativity and kinetic theory. The project will provide training for undergraduate and graduate students and include the creation of a summer school at the intersection of computational relativity and plasma astrophysics. The researchers will perform the first numerical simulations of the crustal shattering mechanism, which is the leading hypothesis for the production of a precursor. To uncover the actual emission mechanism in the system, they will calculate the efficiency of coherent emission mechanisms associated with mergers of plasmoids in relativistic magnetic reconnection, in regimes applicable to the magnetospheres of compact object mergers and magnetars. Finally, they will explore a novel radiative regime of reconnection in strong magnetic fields and calculate the spectrum of escaping high-energy X-ray photons. The results (including predicted frequency ranges and luminosity scalings with system parameters) and simulation codes provided by the research team will be directly relevant for multi-messenger observations of NS-NS and NS-BH mergers. This summer school program will fill a gap in the training opportunities of early career scientists, preparing them for research forefront of relativistic and multi-messenger astrophysics. In addition, postdoctoral scholars and graduate students supported by this project will receive extensive professional, educational, and equity, diversity, and inclusion training, including transferable skills acquired through work on this project. This will enable them to be well-positioned throughout their careers to contribute also to technical advances and discoveries in other areas of science and engineering. This award advances the goals of the 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.

当今天体物理学的一个核心问题是了解中子星（NS），高度紧凑的天体或黑洞（BH）的NS的合并。此类合并产生重力波（GW），对应电磁信号，最终是宇宙中最重的原子元素。 除了在此类系统合并期间和之后产生的对应物外，由于灵感NS中存在强磁场，还可以在碰撞前发生迅速的瞬态事件。最近报道了长伽马射线爆发GRB 211211a的这种先驱事件。 通过协助对GW余气的后续搜索，以及限制当前无法接近的参数，例如预合并系统中的磁场强度等当前无法接近的参数，了解迅速启动此类瞬变将是迅速天空定位的附加工具至关重要的。加利福尼亚理工学院与马里兰州大学公园的研究合作将通过一般相对论和动力学理论的计算机模拟计划调查这些问题。 该项目将为本科生和研究生提供培训，并包括在计算相对性和等离子体天体物理学的交汇处创建一所暑期学校。 研究人员将对地壳破碎机制进行第一个数值模拟，这是前体生产的主要假设。 为了揭示系统中的实际发射机制，他们将计算与相对论磁重新连接中浆液合并相关的相干发射机制的效率，在适用于紧凑型物体合并和磁铁磁层的机制中。最后，他们将探索在强磁场中重新连接的新型辐射状态，并计算出逃脱高能量X射线光子的频谱。结果（包括具有系统参数的预测频率范围和光度量表）以及研究团队提供的仿真代码将与NS-NS和NS-BH合并的多通信器观察直接相关。 这项暑期学校计划将填补早期职业科学家的培训机会的空白，为他们准备相对论和多门交易的天体物理学的研究前列。此外，该项目支持的博士后学者和研究生将获得广泛的专业，教育和公平，多样性和包容性培训，包括通过该项目的工作获得的可转移技能。这将使他们在整个职业生涯中都能得到很好的位置，也可以为科学和工程其他领域的技术进步和发现做出贡献。 该奖项促进了宇宙大意上的窗口的目标。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评论标准来评估值得支持的。

项目成果

Electromagnetic Precursors to Black Hole–Neutron Star Gravitational Wave Events: Flares and Reconnection-powered Fast Radio Transients from the Late Inspiral

• DOI: 10.3847/2041-8213/acfdae
• 发表时间: 2023-09
• 期刊: The Astrophysical Journal Letters
• 作者: E. Most;A. Philippov