太阳耀斑中轻度相对论电子的光谱演化
Spectral evolution of mildly relativistic electrons in solar flares
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中文总结 AI 辅助
研究太阳耀斑中负责微波发射的轻度相对论电子光谱演化，通过观测十二次耀斑的微波发射，发现其遵循软-硬-软模式，光谱指数范围广，与发射通量和亮度温度相关，揭示了耀斑中粒子加速的固有属性。
中文摘要 AI 辅助
太阳耀斑是能将周围等离子体粒子加速到高非热能的强大引擎，粒子能谱是关键特征。众多非热硬X射线发射研究表明，数十keV能量的非热电子典型光谱演化在脉冲事件中呈软-硬-软模式，在一些长持续时间事件中呈软-硬-更硬模式。本文将光谱演化研究扩展到主要负责耀斑微波发射的耀斑加速轻度相对论电子情况。通过研究十二次太阳耀斑中扩展欧文斯谷太阳阵列观测到的空间分辨微波发射，发现其通常也遵循软-硬-软光谱演化。但轻度相对论电子的光谱演化覆盖范围从2 - 4到15或更大，比产生X射线的电子更显著。光谱指数演化与发射通量密切相关且无明显时间延迟，与亮度温度也有显著相关性。我们得出结论，所揭示的关系和演化模式是太阳耀斑中粒子加速的固有属性。
英文摘要
Solar flares are a powerful engine capable of accelerating ambient plasma particles to high nonthermal energies. A key characteristic of these particles is their energy spectrum. Numerous studies of nonthermal hard X-ray emission established that a typical spectral evolution of the nonthermal electrons with energies of dozens keV follows a soft-hard-soft pattern in impulsive events and soft-hard-harder pattern in some long-duration events. Here we extend the study of the spectral evolution to the case of flare-accelerated mildly relativistic electrons primarily responsible for the flare microwave emission. We examine the spatially resolved microwave emission observed with the Expanded Owens Valley Solar Array in twelve solar flares and find that they also typically follow a soft-hard-soft spectral evolution. However, the revealed spectral evolution of the mildly relativistic electrons covers the spectral index range from 2-4 to 15 or more and, thus, is much more prominent than for the X-ray-producing electrons. The evolution of the spectral index is closely correlated with the emission flux and does not show any noticeable time delay. The spectral index displays a prominent correlation with the brightness temperature with a pattern similar to all events considered. We conclude that the revealed relationships and the evolutionary pattern is an inherent property of particle acceleration in the solar flares.
