Determination of Low-Energy Cutoffs and Total Energy of Nonthermal Electrons in a Solar Flare on 2002 April 15
Determination of Low-Energy Cutoffs and Total Energy of Nonthermal Electrons in a Solar Flare on 2002 April 15
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DOI：
10.1086/430086
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发表时间：
2005-06
期刊：
影响因子：
--
通讯作者：
L. Sui;G. Holman;B. Dennis
中科院分区：
文献类型：
--
作者：
L. Sui;G. Holman;B. Dennis
加速电子能谱低能截止区的确定对于估算太阳耀斑的总非热能具有决定性意义。由于热韧致辐射在耀斑X射线光谱的低能部分占主导地位，因此很难单独用光谱拟合来确定截止能量。我们已经使用了一种新的方法，结合空间，光谱和时间分析，以确定截止能量的M1.2耀斑观测与RHESSI在2002年4月15日。需要24 ± 2 keV的低能量截止，以确保假设的热发射总是在低能量（<20 keV）下占主导地位，并且光谱拟合结果与RHESSI光变曲线和图像一致。在这个截止能量下，我们得到电子的总非热能为（1.6 ± 1）× 1030尔格，与热等离子体的峰值能量相当，假设填充因子为1，RHESSI观测估计的峰值能量为（6 ± 0.6）× 1029尔格。
The determination of the low-energy cutoff to the spectrum of accelerated electrons is decisive for the estimation of the total nonthermal energy in solar flares. Because thermal bremsstrahlung dominates the low-energy part of flare X-ray spectra, this cutoff energy is difficult to determine with spectral fitting alone. We have used a new method that combines spatial, spectral, and temporal analysis to determine the cutoff energy for the M1.2 flare observed with RHESSI on 2002 April 15. A low-energy cutoff of 24 ± 2 keV is required to ensure that the assumed thermal emissions always dominate over nonthermal emissions at low energies (<20 keV) and that the spectral fitting results are consistent with the RHESSI light curves and images. With this cutoff energy, we obtain a total nonthermal energy in electrons of (1.6 ± 1) × 1030 ergs that is comparable to the peak energy in the thermal plasma, estimated from RHESSI observations to be (6 ± 0.6) × 1029 ergs assuming a filling factor of 1.