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Measurement of magnetic field and relativistic electrons along a solar flare current sheet
Nature Astronomy ( IF 14.1 ) Pub Date : 2020-07-27 , DOI: 10.1038/s41550-020-1147-7
Bin Chen , Chengcai Shen , Dale E. Gary , Katharine K. Reeves , Gregory D. Fleishman , Sijie Yu , Fan Guo , Säm Krucker , Jun Lin , Gelu M. Nita , Xiangliang Kong

In the standard model of solar flares, a large-scale reconnection current sheet is postulated to be the central engine for powering the flare energy release1,2,3 and accelerating particles4,5,6. However, where and how the energy release and particle acceleration occur remain unclear owing to the lack of measurements of the magnetic properties of the current sheet. Here we report the measurement of the spatially resolved magnetic field and flare-accelerated relativistic electrons along a current-sheet feature in a solar flare. The measured magnetic field profile shows a local maximum where the reconnecting field lines of opposite polarities closely approach each other, known as the reconnection X point. The measurements also reveal a local minimum near the bottom of the current sheet above the flare loop-top, referred to as a ‘magnetic bottle’. This spatial structure agrees with theoretical predictions1,7 and numerical modelling results. A strong reconnection electric field of about 4,000 V m−1 is inferred near the X point. This location, however, shows a local depletion of microwave-emitting relativistic electrons. These electrons instead concentrate at or near the magnetic bottle structure, where more than 99% of them reside at each instant. Our observations suggest that the loop-top magnetic bottle is probably the primary site for accelerating and confining the relativistic electrons.



中文翻译:

沿着太阳耀斑电流片测量磁场和相对论电子

在太阳耀斑的标准模型中,假定大规模重新连接电流表是为火炬能量释放1,2,3提供动力并加速粒子4,5,6的中央引擎。然而,由于缺乏对当前薄板的磁性能的测量,尚不清楚在何处以及如何发生能量释放和粒子加速。在这里,我们报告了沿太阳耀斑中电流表特征对空间分辨磁场和耀斑加速的相对论电子的测量。测得的磁场轮廓显示了一个局部最大值,在该处,极性相反的重新连接磁场线彼此靠近,称为重新连接X点。这些测量还揭示了在火炬回路顶部上方当前工作表底部附近的局部最小值,称为“磁性瓶”。这种空间结构与理论预测1,7和数值模拟结果一致。约4,000 V m的强重新连接电场在X点附近推断-1。但是,该位置显示了发射微波的相对论电子的局部耗尽。这些电子取而代之地集中在磁性瓶结构处或附近,在那里每个时刻有超过99%的电子存在。我们的观察表明,环形磁瓶可能是加速和限制相对论电子的主要场所。

更新日期:2020-07-27
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