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Abstract The SOL2013-10-28T02:02:58L133C110 flare occurred on the western limb, acquiring the GOES class of X1.0, and we focus on an oscillatory phenomenon detected at 34 GHz by the Nobeyama Radioheliograph (NoRH) during this flare. The oscillation is less obvious at 17 GHz and is unseen for a hard X-ray source detected by the RHESSI. In the 94 Å images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we traced the evolution of the extreme ultraviolet (EUV) images capturing an eruption around 01:58 UT over the location of the RHESSI 50–100 keV source. We located the microwave emitting loop inferred from the 17/34 GHz maps within the complex EUV loop systems, and performed a model calculation of the dynamic evolution of the microwave brightness, including the radiative transfer in a magnetically asymmetric loop and evolving nonthermal electrons. The results demonstrate that a quasiperiodic injection of energetic electrons at a fixed spatial point is sufficient to reproduce such an oscillatory motion, without an actual shift of the nonthermal electron injection point, and that the magnetic environment required for the microwave loop model is consistent with the observed EUV activities related to the overall reconnection geometry. 

Abstract We investigate the eruptive process of two filaments, which is associated with an M-class flare that occurred in 2011 August 4. The filaments are partly overlapped, one in the active region and the other just beside it, and erupt together as a halo coronal mass ejection. For this study, we used the Atmospheric Imaging Assembly and the Heliospheric Magnetic Imager on board the Solar Dynamics Observatory, the Nobeyama Radioheliograph 17 GHz, and the RHESSI Hard X-ray satellite. We found three distinct phases in the microwave flux profile and in the rising pattern of the filaments during the event. In the first phase, there was weak nonthermal emission at 17 GHz and hard X-rays. Those nonthermal sources appeared on one edge of the western filament (F2) in the active region. The F2 began to be bright and rose upward rapidly, while the eastern filament (F1), which was extended to the quiet region, started to brighten from the peak time of the 17 GHz flux. In the second phase, the nonthermal emission weakened and the F2 rose up slowly, while the F1 began to rise up. In the third phase, two filaments erupted together. Since the F1 was stable for a long time in the quiet region, breaking the equilibrium state of the F1 would be decisive for the successful eruption of two filaments and it seems clear that the evolution of the F2 provoked the unstable F1. We suggest that tether-cutting reconnection between two overlapped filaments triggers the eruption of the two filaments as a tangled identity.