Radiative shocks in gamma-ray bursts

伽马射线暴中的辐射冲击

• 批准号: 1412485
• 负责人: Andrei Beloborodov
• 金额: $ 57.45万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1412485&HistoricalAwards=false
• 关键词: Radiative; shocks; gamma; ray; bursts

Gamma-ray bursts (GRBs) are an extreme variety of cosmic explosion and perhaps the most powerful events yet discovered. After a lot of work, GRBs are now known to be at large distances, significant fractions of the size of the universe. They come from very high speed jets of material shot out by short-lived compact sources, possibly during the formation of black holes. At least in some cases, GRBs are associated with the collapse of very massive stars of the type called Wolf-Rayet. This work should make transformative progress on a major goal of GRB theory, which is to use available observations all the way from low energies (long wavelengths, radio data) to the highest energies (short wavelength, gamma rays), to reconstruct the explosion, determining the composition of the jets, how they are made, how they emit gamma rays, and how they interact with their surroundings. Junior researchers at the beginning of their careers will learn about complex theories and computer simulations and contribute to the understanding of fundamental physics and the properties of matter in extreme conditions.This research will revisit the mechanism of shocks in GRBs, and analyze their radiative properties. It will use ab initio numerical simulations to investigate a new type of sub-photospheric shock. By following shock formation and propagation on a microscopic level, these simulations will fully describe the dissipation mechanism and the radiation produced. These results will then be tested against observations. The study includes work on a mechanism for the observed GeV flashes in GRBs which has already raised new questions about the physics of the external blast waves from GRB explosions, and in particular suggests the possibility of a non-linear shock which has a strong precursor and involves ultra-high-energy electron-positron pairs. Both the simulation method and the shock mechanism are novel and could potentially uncover unexpected features in the blast wave mechanism. The research impacts fundamental physics by understanding new properties of matter in extreme conditions. Educational impacts include the training of junior researchers and incorporation of results into instructional courses.

伽马射线暴（GRBs）是一种极端的宇宙爆炸，也许是迄今为止发现的最强大的事件。经过大量的研究，现在已知伽马射线暴距离很远，占宇宙大小的很大一部分。它们来自于可能在黑洞形成过程中由短暂的致密源射出的高速物质射流。至少在某些情况下，伽马射线暴与沃尔夫-拉叶特大质量恒星的坍缩有关。这项工作将在GRB理论的一个主要目标上取得革命性的进展，即利用现有的观测数据，从低能量（长波，无线电数据）到最高能量（短波，伽马射线），重建爆炸，确定喷流的组成，它们是如何形成的，它们是如何发射伽马射线的，以及它们如何与周围环境相互作用。初级研究人员在其职业生涯的开始将学习复杂的理论和计算机模拟，并有助于理解基础物理学和极端条件下物质的性质。本研究将重新审视grb中的冲击机制，并分析其辐射特性。它将使用从头算数值模拟来研究一种新型的亚光球激波。通过在微观水平上跟踪激波的形成和传播，这些模拟将充分描述耗散机制和产生的辐射。这些结果将根据观察结果进行检验。这项研究包括对GRB中观测到的GeV闪光机制的研究，这已经提出了关于GRB爆炸外部爆炸波的物理学的新问题，特别是提出了非线性冲击的可能性，这种冲击具有很强的前体，涉及超高能量的电子-正电子对。模拟方法和激波机理都是新颖的，有可能揭示冲击波机理中意想不到的特征。这项研究通过了解极端条件下物质的新特性，影响了基础物理学。教育方面的影响包括培训初级研究人员和将成果纳入教学课程。