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arXiv 0908.2339astro-ph.SRastro-ph.EP
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X级耀斑的亚毫米波和X射线观测

Submillimeter and X-ray observations of an X Class flare

C. G. Gimenez de Castro, G. Trottet, A. Silva-Valio, S. Krucker, J. E. R. Costa, P. Kaufmann, E. Correia, H. Levato

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Accpeted in Astronomy & Astrophysics. 9 Pages, 6 Figures ADDED REFERENCES
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摘要：

2002年8月30日13时27分30秒发生的GOES X1.5级耀斑是迄今为止在亚毫米波段探测到的少数事件之一。我们提出了一个详细的分析，这个耀斑结合无线电观测从1.5到212 GHz（上限的流量也提供了在405 GHz）和X射线。尽管对高达212 GHz的射电发射的观测表明，能量为几兆电子伏的相对论电子被加速，但RHESSI在~ 250 keV以上没有检测到明显的硬X射线发射。在12- 20和50- 100 keV的图像揭示了一个非常紧凑，但解决，源约10”× 10”。EUV TRACE图像显示了一个多核结构，表明一个复杂的（多极）磁拓扑结构。在峰值时间，无线电频谱显示出从~ 7 GHz到35 GHz的扩展平坦度。将射电光谱的光学薄部分建模为回旋同步辐射，我们得到了电子光谱（光谱指数δ，发射电子的瞬时数）。结果表明，为了保持预期的X射线发射从相同的发射电子低于RHESSI背景在250 keV，磁场高于500 G是必要的。另一方面，从射电观测中推导出的电子谱>= 50 GHz比从~ 70 - 250 keV X射线数据中推导出的电子谱更难，这意味着必须存在几百keV左右的破缺能量。在脉冲相的衰减过程中，观察到X射线谱的硬化现象，这是由于俘获电子在电子密度为n_e ~ 3E_（10 - 5）E_（10）cm ~（-3）的介质中发生库仑碰撞而扩散所产生的电子分布谱的硬化。

英文摘要：

The GOES X1.5 class flare that occurred on August 30,2002 at 1327:30 UT is one of the few events detected so far at submillimeter wavelengths. We present a detailed analysis of this flare combining radio observations from 1.5 to 212 GHz (an upper limit of the flux is also provided at 405 GHz) and X-ray. Although the observations of radio emission up to 212 GHz indicates that relativistic electrons with energies of a few MeV were accelerated, no significant hard X-ray emission was detected by RHESSI above ~ 250 keV. Images at 12--20 and 50--100 keV reveal a very compact, but resolved, source of about ~ 10" x 10". EUV TRACE images show a multi-kernel structure suggesting a complex (multipolar) magnetic topology. During the peak time the radio spectrum shows an extended flatness from ~ 7 to 35 GHz. Modeling the optically thin part of the radio spectrum as gyrosynchrotron emission we obtained the electron spectrum (spectral index delta, instantaneous number of emitting electrons). It is shown that in order to keep the expected X-ray emission from the same emitting electrons below the RHESSI background at 250 keV, a magnetic field above 500 G is necessary. On the other hand, the electron spectrum deduced from radio observations >= 50 GHz is harder than that deduced from ~ 70 - 250 keV X-ray data, meaning that there must exist a breaking energy around a few hundred keV. During the decay of the impulsive phase, a hardening of the X-ray spectrum is observed which is interpreted as a hardening of the electron distribution spectrum produced by the diffusion due to Coulomb collisions of the trapped electrons in a medium with an electron density of n_e ~ 3E10 - 5E10 cm-3.

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