2013年11月7日耀斑期间观测到的窄带尖峰
Narrowband Spikes Observed during the 2013 November 7 Flare
摘要：
几十年来，人们在太阳耀斑中观测到窄带尖峰。然而，其确切的起源仍在讨论中。为了有助于理解这些尖峰，我们分析了2013年11月7日耀斑脉冲阶段期间在800-2000 MHz范围内观察到的窄带尖峰。在无线电频谱中，尖峰开始于典型的宽带尖峰云，然后它们在频率上的分布变成了独特的，非常窄的频带，具有非整数频率比。我们成功地拟合了这些窄峰带的频率，计算了Bernstein模的色散分支和增长率。为了进行比较，我们还分析了模型，其中尖峰的窄带在上混合频率处产生。利用这两种模型，我们估计等离子体密度和磁场尖峰源。然后对模型进行了讨论，并提出了支持伯恩斯坦模型的论点。用傅里叶方法分析了这一尖峰事件的频率分布，得到了其幂律指数在-0.8 - -2.75区间内变化的幂律谱。因为在某些时候，这个幂律指数接近Kolmogorov谱指数（-5/3），我们建议，尖峰产生通过伯恩斯坦模式在湍流等离子体重联流出或直接在湍流磁重联的太阳耀斑。
英文摘要：
Narrowband spikes are observed in solar flares for several decades. However, their exact origin is still discussed. To contribute to understanding of these spikes, we analyze the narrowband spikes observed in the 800-2000 MHz range during the impulsive phase of the November 7, 2013 flare. In the radio spectrum, the spikes started with typical broadband clouds of spikes, and then their distribution in frequencies changed into unique, very narrow bands having non-integer frequency ratios. We successfully fitted frequencies of these narrow spike bands by those, calculating dispersion branches and growth rates of the Bernstein modes. For comparison, we also analyzed the model, where the narrow bands of spikes are generated at the upper-hybrid frequencies. Using both models, we estimated the plasma density and magnetic field in spike sources. Then the models are discussed, and arguments in favor of the model with the Bernstein modes are presented. Analyzing frequency profiles of this spike event by the Fourier method, we found the power-law spectra with the power-law indices varying in the -0.8 -- -2.75 interval. Because at some times this power-law index was close to the Kolmogorov spectral index (-5/3), we propose that the spikes are generated through the Bernstein modes in turbulent plasma reconnection outflows or directly in the turbulent magnetic reconnection of solar flares.
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