Collaborative Research: Short Gamma-Ray Bursts Arising From Misaligned Structured Jets in the Dawn of Gravitational Wave Astronomy

合作研究：引力波天文学初期由未对准的结构喷流引起的短伽马射线暴

基本信息

批准号：
1816136
负责人：
Dimitrios Giannios
金额：
$ 13.58万
依托单位：
Purdue 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：
2018-09-01 至 2021-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1816136&HistoricalAwards=false
关键词：
Collaborative Research Short Gamma Ray

项目摘要

The detection of both gravitational waves (GWs) from a neutron star (NS) merger event and its electromagnetic (EM) counterpart marks a new era in multi-messenger astronomy. The detection of the faint short gamma-ray burst (GRB), GRB170817A, the EM counterpart of a gravitational wave event provides the most conclusive evidence that NS mergers are indeed the progenitors of short GRBs. The need to fully understand the EM signals from GRBs is even more pressing after this discovery. A research collaboration between California State University, Sacramento, Purdue University, and Northwestern University will investigate short GRBs and how they are produced by jets, or beamed outflows of ionized matter, which have geometrical structure. When such jets are misaligned with respect to the direction from the GRB to earth, they are observed to be under-luminous, or relatively faint, as was seen for GRB170817A. The researchers will use relativistic magneto-hydrodynamical (MHD) simulations to fully explain current and future observations of EM counterparts from GW signals. An important component of this proposed research is training both graduate and undergraduate students, who will be encouraged to conduct original research projects. The research team will also broaden participation in science and public literacy with a series of public lectures at the soon-to-be opened Sacramento State planetarium. They will also continue outreach efforts at the three campuses, including public solar viewing parties, engaging grade 6-12 students with hands-on activities and assisting high school educators to design hands-on classroom demonstrations.The proposal team will expand on its correct prediction that the most likely electromagnetic signal from a neutron star merger event would be a faint gamma-ray pulse from a misaligned GRB jet. Based on preliminary MHD simulations of a short GRB jet, the team found that a jet is naturally expected to have some structure, where the jet's properties vary smoothly with angle, such that the luminous core is surrounded by a slower, fainter sheath, consistent with observations of GRB170817A. The researchers will carry out large-scale relativistic MHD simulations of short GRB jets in realistic ambient gas profiles and realistic initial black hole conditions in order to determine the structure of the jet. Through these simulations, they will follow the jet from the launching region, through the confining ambient gas and the break out distance, where its slower sheath forms, all the way to the transparency region where the gamma-ray signal is expected to be produced. The work will be complemented by analytical studies of jet collimation by a confining medium as the jet breaks out from it. The team will calculate the expected signal from a jet pointed at an arbitrary angle to the observer for a broad range of prompt emission models and from the accompanying long-term afterglow emission.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.

从中子星（NS）合并事件及其电磁（EM）对应物中检测出两个引力波（GWS）标志着多通信者天文学的新时代。检测微弱的短伽马射线爆发（GRB），GRB170817A，引力波事件的EM对应物提供了最终的证据，证明NS合并确实是短GRB的祖细胞。在这一发现之后，需要充分了解GRB的EM信号的需求更加紧迫。加利福尼亚州立大学，萨克拉曼多，普渡大学和西北大学之间的研究合作将调查短期GRB，以及它们是如何由喷气机产生的，或散发出具有几何结构的电离物质的流出。当这种喷气机相对于从GRB到地球的方向错位时，正如GRB170817A所看到的那样，它们被观察到它们是透露不足或相对较弱的。研究人员将使用相对论的磁融化（MHD）模拟来充分解释GW信号对EM对应物的当前和将来的观察结果。这项拟议的研究的一个重要组成部分是培训研究生和本科生，他们将被鼓励进行原始研究项目。研究团队还将在即将开设的萨克拉曼多州天文馆的一系列公开演讲中扩大对科学和公共素养的参与。他们还将继续在这三个校园中进行外展工作，包括公共太阳能观看聚会，使6至12年级的学生通过动手活动吸引学生，并协助高中教育工作者设计动手的课堂演示。提案团队将根据其最有可能发出的中性星星合并事件的电磁信号来扩展，这是一个淡淡的gama-ray pulse table grb ray pulse a Fuls a Fuls a Misalcimnigned Grb Grb jet。基于短GRB射流的初步MHD模拟，该小组发现，射流自然具有一定的结构，在该结构中，射流的性质随角度平稳而变化，因此发光芯被较慢，柔软的鞘与GRB170817A的观察一致。研究人员将对现实的环境气体剖面和现实的初始黑洞条件进行大规模的相对论MHD模拟，以确定射流的结构。通过这些模拟，它们将沿着发射区域的喷气机，通过狭窄的环境气体和断裂距离，在该距离形成较慢的鞘形，一直到预计会产生伽马射线信号的透明度区域。随着射流爆发，通过限制培养基对喷气准则进行分析研究，这项工作将得到补充。该团队将计算出与观察者的任意角度的喷气机的预期信号，并从随附的长期余潮排放中计算出。这项奖项反映了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审查标准来通过评估来通过评估来获得支持的。