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arXiv 2301.13682astro-ph.SR
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太阳耀斑中空间扩展的湍流电子加速与传输的光谱与成像诊断

Spectral and Imaging Diagnostics of Spatially-Extended Turbulent Electron Acceleration and Transport in Solar Flares

Morgan Stores, Natasha L. S. Jeffrey, James A. McLaughlin

AI总结:

本研究使用Fokker-Planck方程模拟太阳耀斑中扩展湍流加速区域内的电子加速与传输,通过结合X射线光谱和成像诊断,为约束耀斑加速机制的性质奠定了基础。

摘要:

太阳耀斑是高效的粒子加速器,其释放的磁能中有很大一部分(10-50%)转化为高能粒子,例如产生硬X射线的电子。这一能量传递过程尚未得到很好的约束,关于加速机制存在相互竞争的理论,包括MHD湍流。我们进行了一项详细的参数研究,考察加速区域的多种性质(包括其空间范围和湍流的空间分布)如何影响观测到的电子性质,例如那些通常通过X射线成像和光谱学确定的性质。本文使用一个与时间无关的Fokker-Planck方程来描述耀斑电子在有限温度的日冕等离子体中的加速和传输。受近期表明日冕环中存在扩展湍流区域的非热谱线展宽观测的启发,该模型纳入了一个扩展的湍流加速区域。我们生成了密度加权电子通量的输出,该量与观测到的X射线直接相关,并在从日冕到色球的空间和能量维度上进行了建模。我们发现,通过结合多种光谱和成像诊断(如光谱指数差异或比值、能量或空间相关的通量比值,以及电子进入色球的深度),可以同时约束加速性质(包括时间尺度和速度依赖性)与空间性质。我们的诊断方法为仅通过X射线成像光谱学约束单个耀斑的加速性质奠定了基础,并可应用于过去、当前和未来的观测,包括来自RHESSI和Solar Orbiter的观测。

英文摘要:

Solar flares are efficient particle accelerators with a large fraction of released magnetic energy (10-50%) converted into energetic particles such as hard X-ray producing electrons. This energy transfer process is not well constrained, with competing theories regarding the acceleration mechanism(s), including MHD turbulence. We perform a detailed parameter study examining how various properties of the acceleration region, including its spatial extent and the spatial distribution of turbulence, affect the observed electron properties, such as those routinely determined from X-ray imaging and spectroscopy. Here, a time-independent Fokker-Planck equation is used to describe the acceleration and transport of flare electrons through a coronal plasma of finite temperature. Motivated by recent non-thermal line broadening observations that suggested extended regions of turbulence in coronal loops, an extended turbulent acceleration region is incorporated into the model. We produce outputs for the density weighted electron flux, a quantity directly related to observed X-rays, modelled in energy and space from the corona to chromosphere. We find that by combining several spectral and imaging diagnostics (such as spectral index differences or ratios, energy or spatial-dependent flux ratios, and electron depths into the chromosphere) the acceleration properties, including the timescale and velocity dependence, can be constrained alongside the spatial properties. Our diagnostics provide a foundation for constraining the properties of acceleration in an individual flare from X-ray imaging spectroscopy alone, and can be applied to past, current and future observations including those from RHESSI and Solar Orbiter.

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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