RECONNECTION-POWERED LINEAR ACCELERATOR AND GAMMA-RAY FLARES IN THE CRAB NEBULA
RECONNECTION-POWERED LINEAR ACCELERATOR AND GAMMA-RAY FLARES IN THE CRAB NEBULA
复制标题
蟹状星云中重新连接驱动的线性加速器和伽马射线耀斑
DOI：
10.1088/2041-8205/737/2/l40
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
["D. Uzdensky
中科院分区：
文献类型：
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作者：
["D. Uzdensky
最近在蟹状星云中发现了长达一天的伽马射线耀斑，推测是PeV（1015 eV）电子在毫高斯磁场中的同步辐射，这对粒子加速模型提出了强烈的挑战。观测到的光子能量超过了在电场小于磁场的标准条件下通过平衡加速率和同步辐射损失而获得的上限（100 MeV）。我们认为，线性电加速器，在磁重联网站，是能够绕过这个困难。能量足够大的电子具有如此大的回旋半径，以至于它们的运动对重联层中的小尺度湍流结构不敏感，并且仅由大尺度场控制。我们表明，这样的粒子被引导到重联层的反向磁场，因为它们被加速的重联电场。当这些电子被限制在电流片内时，它们会经历一个下降的垂直磁场，该磁场可能会下降到加速电场以下。这使它们能够在遭受辐射损失之前达到更高的能量，从而发出超过100 MeV极限的同步辐射，为蟹状星云伽马射线耀斑悖论提供了一个自然的解决方案。
The recent discovery of day-long gamma-ray flares in the Crab Nebula, presumed to be synchrotron emission by PeV (1015 eV) electrons in milligauss magnetic fields, presents a strong challenge to particle acceleration models. The observed photon energies exceed the upper limit (∼100 MeV) obtained by balancing the acceleration rate and synchrotron radiation losses under standard conditions where the electric field is smaller than the magnetic field. We argue that a linear electric accelerator, operating at magnetic reconnection sites, is able to circumvent this difficulty. Sufficiently energetic electrons have gyroradii so large that their motion is insensitive to small-scale turbulent structures in the reconnection layer and is controlled only by large-scale fields. We show that such particles are guided into the reconnection layer by the reversing magnetic field as they are accelerated by the reconnection electric field. As these electrons become confined within the current sheet, they experience a decreasing perpendicular magnetic field that may drop below the accelerating electric field. This enables them to reach higher energies before suffering radiation losses and hence to emit synchrotron radiation in excess of the 100 MeV limit, providing a natural resolution to the Crab gamma-ray flare paradox.