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

• 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

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.

中子星星合并事件产生的引力波及其电磁波的探测标志着多信使天文学进入了一个新的时代。微弱的短伽玛射线暴（GRB 170817 A）的探测，引力波事件的EM对应物提供了最确凿的证据，NS合并确实是短伽玛射线暴的祖先。 在这一发现之后，完全理解伽马射线暴的电磁信号的需要更加紧迫。 加州州立大学、萨克拉门托、普渡大学和西北大学之间的一项研究合作将调查短伽马射线暴以及它们是如何由具有几何结构的射流或电离物质的光束流出产生的。 当这样的喷流与GRB到地球的方向不一致时，它们被观察到是欠亮的，或者相对较暗，就像GRB 170817 A一样。 研究人员将使用相对论磁流体动力学（MHD）模拟来充分解释GW信号中EM对应物的当前和未来观测。 这项拟议研究的一个重要组成部分是培训研究生和本科生，鼓励他们进行原创性研究项目。 研究小组还将在即将开放的萨克拉门托州立天文馆举办一系列公开讲座，以扩大科学和公众素养的参与。 他们还将继续在三个校区开展外展工作，包括举办公众太阳观测派对，让6-12年级的学生参与动手活动，并协助高中教育工作者设计动手课堂演示。提案小组将扩大其正确预测，即中子星星合并事件最有可能的电磁信号是来自未对准的GRB喷流的微弱伽马射线脉冲。 基于对短GRB喷流的初步MHD模拟，研究小组发现，喷流自然会具有某种结构，喷流的性质随角度而平滑变化，因此发光的核心被较慢，较暗的鞘所包围，与GRB 170817 A的观察结果一致。研究人员将在真实的环境气体剖面和真实的初始黑洞条件下对短GRB射流进行大规模相对论MHD模拟，以确定射流的结构。通过这些模拟，他们将跟随从发射区域的射流，通过封闭的环境气体和爆发距离，在那里形成较慢的鞘层，一直到预计产生伽马射线信号的透明区域。这项工作将通过分析研究喷流从约束介质中爆发时的喷流准直来补充。该团队将计算喷流以任意角度指向观察者的预期信号，用于广泛的瞬发发射模型，并从伴随的长时间发射模型中计算。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。

项目成果

Shock-powered radio precursors of neutron star mergers from accelerating relativistic binary winds

• DOI: 10.1093/mnras/staa3794
• 发表时间: 2020-10
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: N. Sridhar;J. Zrake;B. Metzger;L. Sironi;D. Giannios

First-principles Prediction of X-Ray Polarization from Magnetic Reconnection in High-frequency BL Lacertae Objects

高频 BL Lacertae 物体磁重联 X 射线偏振的第一性原理预测

• DOI: 10.3847/1538-4357/abf2be
• 发表时间: 2021
• 期刊: The Astrophysical Journal
• 作者: Zhang, Haocheng;Li, Xiaocan;Giannios, Dimitrios;Guo, Fan
• 通讯作者: Guo, Fan

Radiation signatures from striped blazar jet

条纹布拉泽射流的辐射特征

• DOI: 10.1093/mnras/stab008
• 发表时间: 2021
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Zhang, Haocheng;Giannios, Dimitrios
• 通讯作者: Giannios, Dimitrios

Inverse Compton signatures of gamma-ray burst afterglows

• DOI: 10.1093/mnras/staa1583
• 发表时间: 2019-10
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Hao Zhang;I. Christie;M. Petropoulou;J. M. Rueda-Becerril;D. Giannios

Blazar jets launched with similar energy per baryon, independently of their power

• DOI: 10.1093/mnras/staa3925
• 发表时间: 2021-01
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: J. M. Rueda-Becerril;A. Harrison;D. Giannios