Evidence for Resonant Transition Radiation in Decimetric Continuum Solar Bursts
Evidence for Resonant Transition Radiation in Decimetric Continuum Solar Bursts
复制标题
DOI：
10.1086/427022
复制
发表时间：
2005-02
期刊：
影响因子：
--
通讯作者：
G. Fleishman;G. Nita;D. Gary
中科院分区：
文献类型：
--
作者：
G. Fleishman;G. Nita;D. Gary
我们研究了在1-18 GHz频率范围内观察到的射电暴的特性，这些射电暴显示出两个不同的光谱分量，峰值在分米（dm）和厘米（cm）范围内。dm发射在频率和时间上都相对平滑，其时间尺度与cm分量的时间尺度相当。这两个光谱分量在它们的时间和光谱行为中显示特定的相关性。通过详细的分析，我们发现：（1）等离子体频率与陀螺频率的比值很大是这些事件的一个特征。(2)dm分量通常显示高度的o模式偏振。(3)dm分量由非相干发射机制产生。(4)dm和cm分量由相同的电子分布产生。(5)产生dm连续谱的快电子的特征能量明显低于产生微波回旋同步加速器组件的电子的能量。(6)dm分量的光谱形状与快电子能量分布没有很好的相关性。这些发现不能很容易地解释与dm太阳爆发发射的标准机制，但同意共振跃迁辐射理论的预测。我们的结论是，这些两个组件的突发事件的一个独特的子类，包括约10%的所有突发，与DM连续组件产生的最有可能的共振跃迁辐射产生的快速电子与小规模的背景等离子体的不均匀性的相互作用。我们讨论了新的可能性耀斑等离子体诊断使用这些两个组件的突发。
We investigate the properties of radio bursts observed in the 1-18 GHz frequency range that display two distinct spectral components peaking at decimetric (dm) and centimetric (cm) ranges. The dm emission is relatively smooth in both frequency and time, with timescales comparable to those of the cm component. The two spectral components display specific correlations in their temporal and spectral behavior. Through detailed analysis, we find the following: (1) A large ratio of plasma frequency to gyrofrequency is a characteristic of all of these events. (2) The dm component generally displays a high degree of o-mode polarization. (3) The dm component is produced by an incoherent emission mechanism. (4) The dm and cm components are generated by the same electron distribution. (5) The characteristic energy of the fast electrons producing the dm continuum is significantly lower than the energy of the electrons generating the microwave gyrosynchrotron component. (6) The spectral shape of the dm component is not well correlated with the fast electron distribution over energy. These findings cannot easily be explained with standard mechanisms for dm solar burst emission but agree well with the predictions of the theory of resonant transition radiation. We conclude that these two-component bursts represent a distinctive subclass of events, comprising about 10% of all bursts, with the dm continuum component generated most probably by resonant transition radiation produced by interaction of fast electrons with small-scale inhomogeneities of the background plasma. We discuss new possibilities for flaring plasma diagnostics using these two-component bursts.