Speaker
Description
Understanding electron acceleration associated with magnetic energy release across short timescales is a major challenge in solar physics. Using subsecond and narrow-bandwidth ($\Delta{f}/f\sim10^{-3}-10^{-2}$) solar radio bursts fine structures, we present a statistical analysis of frequency- and time-resolved imaging of individual radio spikes and type IIIb striae associated with a coronal mass ejection (CME). The CME perturbs the field geometry, leading to increased spike emission likely due to frequent magnetic reconnection. LOFAR imaging reveals that on average, both burst types have a similar source size, fast expansion at millisecond scales, superluminal sky-plane centroid velocities, and intensity contours that overlap for cotemporal bursts. Combined with previous observations above 1 GHz, the average decay time and source size estimates follow a $\sim1/f$ dependence 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 a strong anisotropy of the density fluctuation spectrum. Consequently, the site of the radio-wave emission does not correspond to the observed burst locations and implies acceleration and emission near the CME flank.
