论文标题
干涉成像和横梁形成的研究IV型无线电爆发与Lofar
Interferometric imaging, and beam-formed study of a moving Type IV Radio burst with LOFAR
论文作者
论文摘要
IV型无线电爆发已经研究了50多年。但是，无线电发射机制的细节仍然是一个悬而未决的问题。为了提供有关排放机制的更多信息，我们通过使用低频阵列（LOFAR）的高分辨率能力（2014年8月25日\ textbf {（Sola-d-D-2-21-00188）}，研究了带有精细结构（SPIKE组）的IV型无线电爆发。我们介绍了Nançay射线光（NRH）和第IV型无线电爆发的第一个Lofar成像数据的比较。使用Lofar数据以20 $ \ sim $ 180 MHz的频率计算圆极化度（DCP），发现DCP的值在事件期间逐渐增加，值为10 \％$ \ sim $ 20 \％。将LofAR干涉数据与白光观测值结合使用，以跟踪这种类型IV的传播。运动学显示了无线电的向西运动，比CME前沿慢。 The dynamic spectrum of LOFAR shows a large number of fine structures with duration of less than 1s and high brightness temperature ($T_\mathrm{B}$), i.e. $10^{12}$$\sim$$10^{13}$ K. The gradual increase of DCP supports gyrosynchrotron emission as the most plausible mechanism for the type IV.但是，相干排放（例如电子回旋马仪（ECM））不稳定性可能是小规模细胞结构的原因。无数的精细结构完全负责如此高的$ t_ \ mathrm {b} $。
Type IV radio burst has been studied for over 50 years. However, the specifics of the radio emission mechanisms is still an open question. In order to provide more information about the emission mechanisms, we studied a moving type IV radio burst with fine structures (spike group) by using the high resolution capability of Low-Frequency Array (LOFAR) on Aug 25, 2014\textbf{ (SOLA-D-21-00188)}. We present a comparison of Nançay RadioHeliograph (NRH) and the first LOFAR imaging data of type IV radio burst. The degree of circular polarization (DCP) is calculated at frequencies in the range 20$\sim$180 MHz using LOFAR data, and it was found that the value of DCP gradually increased during the event, with values of 10\%$\sim$20\%. LOFAR interferometric data were combined with white light observations in order to track the propagation of this type IV. The kinematics shows a westward motion of the radio sources, slower than the CME leading edge. The dynamic spectrum of LOFAR shows a large number of fine structures with duration of less than 1s and high brightness temperature ($T_\mathrm{B}$), i.e. $10^{12}$$\sim$$10^{13}$ K. The gradual increase of DCP supports gyrosynchrotron emission as the most plausible mechanism for the type IV. However, coherent emissions such as Electron Cyclotron Maser (ECM) instability can be responsible for small scale fine structures. Countless fine structures altogether were responsible for such high $T_\mathrm{B}$.
