日冕物质抛射触发的亚秒级电子加速的太阳射电尖峰与IIIb型条纹表现
Solar Radio Spikes and Type IIIb Striae Manifestations of Sub-second Electron Acceleration Triggered by a Coronal Mass Ejection
AI总结：
本文利用LOFAR成像统计分析CME相关的太阳射电尖峰与IIIb型条纹，发现两者时空特征高度一致且符合射电波散射预测，揭示了CME侧翼的亚秒级电子加速与发射机制。
摘要：
理解与亚秒级尺度磁能释放相关的电子加速是太阳物理学中的一个重大挑战。观测到的太阳射电尖峰表现为亚秒级、窄带宽（$Δ{f}/f\sim10^{-3}-10^{-2}$）爆发，指示着电子分布的亚秒级演化。本文对与日冕物质抛射（CME）相关的尖峰和IIIb型条纹的频率统计及时间分辨成像进行了分析。LOFAR成像显示，同时发生（$<2$ s）的尖峰和条纹强度等值线几乎完全重叠。平均而言，两种爆发类型具有相似的源尺寸，并在毫秒尺度上快速膨胀。射电源质心速度通常超光速，且在30-45 MHz范围内与频率无关。CME扰动磁场结构，导致尖峰发射增加，可能源于频繁的磁重联。随着磁场恢复至先前构型，观测到的天平面发射位置在几十分钟内漂移至更高高度。结合先前1 GHz以上的观测，平均衰减时间和源尺寸估计在三个频率数量级上遵循$\sim1/f$依赖关系，与射电波散射预测一致。30-70 MHz间爆发的时间和空间特征与密度涨落谱强各向异性的射电波散射一致。因此，射电波发射位置并不对应观测到的爆发位置，暗示加速和发射发生在CME侧翼附近。带宽表明30 MHz处内禀发射源尺寸$<1$角秒，且产生十米波尖峰的事件中磁场强度比平均值大两倍。
英文摘要：
Understanding electron acceleration associated with magnetic energy release at sub-second scales presents a major challenges in solar physics. Solar radio spikes observed as sub-second, narrow bandwidth bursts with $Δ{f}/f\sim10^{-3}-10^{-2}$ are indicative of sub-second evolution of the electron distribution. We present a statistical analysis of frequency, and time-resolved imaging of individual spikes and Type IIIb striae associated with a coronal mass ejection (CME). LOFAR imaging reveals that co-temporal ($<2$ s) spike and striae intensity contours almost completely overlap. On average, both burst types have similar source size with fast expansion at millisecond scales. The radio source centroid velocities are often superluminal, and independent of frequency over 30-45 MHz. The CME perturbs the field geometry, leading to increased spike emission likely due to frequent magnetic reconnection. As the field restores towards the prior configuration, the observed sky-plane emission locations drift to increased heights over tens of minutes. Combined with previous observations above 1 GHz, average decay time and source size estimates follow $\sim1/f$ dependency over three decades in frequency, similar to radio-wave scattering predictions. Both time and spatial characteristics of the bursts between 30-70 MHz are consistent with radio-wave scattering with strong anisotropy of the density fluctuation spectrum. Consequently, the site of radio-wave emission does not correspond to the observed burst locations and implies acceleration and emission near the CME flank. The bandwidths suggest intrinsic emission source sizes $<1$ arcsec at 30 MHz, and magnetic field strengths a factor of two larger than average in events that produce decameter spikes.
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。
