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arXiv 0710.0441astro-ph
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一次太阳耀斑非热辐射的对比分析和电子输运的研究

Comparative Analysis of Non-thermal Emissions and Study of Electron Transport in a Solar Flare

T. Minoshima, T. Yokoyama, N. Mitani

摘要:

利用RHESSI硬X射线(HXR)和Nobeyama微波观测资料,研究了2003年5月29日发生的一次太阳耀斑的非热辐射。这个耀斑显示了HXR和微波辐射的几个典型行为:微波峰相对于HXR峰的时间延迟,环顶微波和足点HXR源,以及从微波光谱推断的电子能量分布比从HXR光谱更硬。此外,我们发现,较高能量($\gsim 100$ keV)的HXR的光谱指数的时间分布是类似的微波,并从较低能量($\lsim 100$ keV)的HXR延迟。我们用一个称为{ \TPP }的电子输运模型来解释这些观测结果。我们数值求解空间均匀的{ \FP }方程,以确定电子在能量和俯仰角空间中的演化。通过比较模型预测的HXR和微波辐射的行为与观测结果,我们讨论了注入耀斑网站的电子的俯仰角分布。我们发现,所观察到的光谱变化可以定性地解释,如果注入的电子有一个俯仰角分布集中垂直于磁场线,而不是各向同性分布。

英文摘要:

We study the non-thermal emissions in a solar flare occurring on 2003 May 29 by using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This flare shows several typical behaviors of the HXR and microwave emissions: time delay of microwave peaks relative to HXR peaks, loop-top microwave and footpoint HXR sources, and a harder electron energy distribution inferred from the microwave spectrum than from the HXR spectrum. In addition, we found that the time profile of the spectral index of the higher-energy ($\gsim 100$ keV) HXRs is similar to that of the microwaves, and is delayed from that of the lower-energy ($\lsim 100$ keV) HXRs. We interpret these observations in terms of an electron transport model called {\TPP}. We numerically solved the spatially-homogeneous {\FP} equation to determine electron evolution in energy and pitch-angle space. By comparing the behaviors of the HXR and microwave emissions predicted by the model with the observations, we discuss the pitch-angle distribution of the electrons injected into the flare site. We found that the observed spectral variations can qualitatively be explained if the injected electrons have a pitch-angle distribution concentrated perpendicular to the magnetic field lines rather than isotropic distribution.

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