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arXiv 1303.4098astro-ph.SRastro-ph.HE
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用射电和X射线光谱学、成像和计时探测2002年4月11日太阳耀斑中电子加速的动力学

Probing Dynamics of Electron Acceleration with Radio and X-ray Spectroscopy, Imaging, and Timing in the 2002 Apr 11 Solar Flare

Gregory D. Fleishman, Eduard P. Kontar, Gelu M. Nita, Dale E. Gary

摘要:

通过对2002年4月11日耀斑的射电和X射线观测资料的详细分析,并结合三维模拟,确定了耀斑加速区直接产生的射电辐射分量。该加速区域无线电分量具有明显不同的(i)光谱,(ii)光变曲线,(iii)空间位置,并且因此(iv)物理参数,其不同于单独识别的、捕获的或沉淀的电子分量的物理参数。为了得到射电源的物理参数的演变,我们应用前向拟合的无线电频谱的时间序列与回旋同步源函数与5至6个自由参数。在加速区的贡献占主导地位的阶段,X射线和射电导出的电子能谱指数彼此一致。在这段时间内,加速电子谱的最大能量随时间单调增加,在大约一分钟的持续时间内从~ 300 keV增加到~ 2 MeV,这表明加速过程的形式是幂律尾的增长;加速区中的快电子停留时间约为2 - 4秒,其比飞行时间长得多,因此需要强扩散模式以抑制自由流传播。加速区有一个相对较强的磁场,B ~ 120 G,热密度较低,小于2 × 10^9 cm^-3。这些加速区域的属性是一致的随机加速机制。

英文摘要:

Based on detailed analysis of radio and X-ray observations of a flare on 2002 April 11 augmented by realistic 3D modeling, we have identified a radio emission component produced directly at the flare acceleration region. This acceleration region radio component has distinctly different (i) spectrum, (ii) light curves, (iii) spatial location, and, thus, (iv) physical parameters from those of the separately identified, trapped or precipitating electron components. To derive evolution of physical parameters of the radio sources we apply forward fitting of the radio spectrum time sequence with the gyrosynchrotron source function with 5 to 6 free parameters. At the stage when the contribution from the acceleration region dominates the radio spectrum, the X-ray- and radio- derived electron energy spectral indices agree well with each other. During this time the maximum energy of the accelerated electron spectrum displays a monotonic increase with time from ~ 300 keV to ~ 2 MeV over roughly one minute duration indicative of an acceleration process in the form of growth of the power-law tail; the fast electron residence time in the acceleration region is about 2 - 4 s, which is much longer than the time of flight and so requires a strong diffusion mode there to inhibit free-streaming propagation. The acceleration region has a relatively strong magnetic field, B ~ 120 G, and a low thermal density, less than 2x10^9 cm^-3. These acceleration region properties are consistent with a stochastic acceleration mechanism.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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