Study of a solar flare on 2005 August 22 observed in hard X-rays and microwaves
Study of a solar flare on 2005 August 22 observed in hard X-rays and microwaves
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研究硬X射线和微波观测到的2005年8月22日太阳耀斑
DOI：
10.1088/1674-4527/15/1/007
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发表时间：
2015
影响因子：
1.8
通讯作者：
Firoz Kazi A.
中科院分区：
文献类型：
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作者：
Liu Zhong-Yin;Li You-Ping;Gan Wei-Qun;Firoz Kazi A.
我们利用鲁文·拉马蒂高能太阳光谱成像仪(RHESSI)的硬X射线(HXR)观测和Nobeama太阳射电天文台的微波(MW)观测，研究了2005年8月22日的耀斑事件(00：54 UT)。HXR时间分布呈现出具有四个连续峰值的衰减良好的准周期脉动，而微波时间分布则跟随相应的峰值。基于这一特点，我们利用Nobeama射电偏振仪的多频数据，以及RHESSI和Nobeama射电日像仪的空间分辨数据，推导出了HXRs和MWs的时间关系。我们发现，MW中的频率相关延迟和HXR中的能量相关延迟都是显著的。此外，在17 GHz和34 GHz下，南源的微波辐射都比北源的辐射延迟，但在相同能量下，不同源的HXR辐射没有明显的延迟。为了更好地理解所有这些长时间延迟，我们用单指数厚靶模型对观测到的HXR谱进行了拟合，得到了不同能量的电子通量，并推测这些延迟可能与扩展的加速过程有关。我们进一步比较了从17 GHz和34 GHz通量得到的微波谱指数与通量密度的时间分布，发现谱指数与HXR通量表现出很强的反相关。
We investigate the 2005 August 22 flare event (00:54 UT) exploiting hard X-ray (HXR) observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and microwave (MW) observations from the Nobeyama Solar Radio Observatory. The HXR time profile exposes well-damped quasi-periodic pulsations with four sequential peaks, and the MW time profile follows the corresponding peaks. Based on this feature, we derive the time relationship of HXRs and MWs with multi-frequency data from the Nobeyama Radio Polarimeter, and the spatially resolvable data from RHESSI and the Nobeyama Radioheliograph. We find that both frequency dependent delays in MWs and energy dependent delays in HXRs are significant. Furthermore, MW emissions from the south source are delayed with respect to those from the north source at both 17 GHz and 34 GHz, but no significant delays are found in HXR emissions from the different sources at the same energies. To better understand all these long time delays, we derive the electron fluxes of different energies by fitting the observed HXR spectra with a single power-law thick-target model, and speculate that these delays might be related to an extended acceleration process. We further compare the time profile of a MW spectral index derived from 17 and 34 GHz fluxes with the flux densities, and find that the spectral index shows a strong anti-correlation with the HXR fluxes.