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arXiv 0802.2558astro-ph
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伽玛暴瞬发和早期余辉的相对论粒子模拟研究

Relativistic Particle-In-Cell Simulation Studies of Prompt and Early Afterglows from GRBs

K. -I. Nishikawa, P. Hardee, Y. Mizuno, M. Medvedev, B. Zhang, D. H. Hartmann, G. J. Fishman

摘要:

从包含相对论喷流和激波的天体物理系统,如伽马射线暴(GRB)、活动星系核(AGN)和微类星体中观测到的非热辐射通常呈现幂律发射谱。最近的PIC模拟的相对论电子-离子(或电子-正电子)射流注入到一个固定的介质中显示,粒子加速发生在下游射流。在无碰撞的相对论激波中,粒子(电子、正电子和离子)的加速是由于在激波区域中产生的等离子体波及其相关的不稳定性(例如韦伯不稳定性)。模拟结果表明,韦伯不稳定性是造成和放大高度不均匀的小尺度磁场的原因。这些场有助于电子在喷射头后面的横向偏转。与假定有均匀磁场的同步辐射相比,偏转电子产生的"抖动“辐射具有不同的性质。抖动辐射对于理解伽马射线暴、相对论喷流和超新星遗迹中复杂的时间演化和/或光谱可能是重要的。

英文摘要:

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks e.g. gamma-ray bursts (GRBs) active galactic nuclei (AGNs) and microquasars commonly exhibit power-law emission spectra. Recent PIC simulations of relativistic electron-ion (or electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In collisionless relativistic shocks particle (electron, positron and ion) acceleration is due to plasma waves and their associated instabilities (e.g. the Weibel (filamentation) instability) created in the shock region. The simulations show that the Weibel instability is responsible for generating and amplifying highly non-uniform small-scale magnetic fields. These fields contribute to the electron's transverse deflection behind the jet head. The resulting ``jitter'' radiation from deflected electrons has different properties compared to synchrotron radiation which assumes a uniform magnetic field. Jitter radiation may be important for understanding the complex time evolution and/or spectra in gamma-ray bursts, relativistic jets in general and supernova remnants.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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