Multiple Magnetic Reconnections Driven by a Large-scale Magnetic Flux Rope

Magnetic flux ropes (MFRs), as the most probable core structure of solar eruptive activity, remain mysterious on their origination, magnetic environment, and erupting mechanisms. Here, we newly identify a large-scale hot channel MFR, named "MFR3", that connects an anti-Hale active region (AR) 11429 and a normal AR 11430 on 2012 March 7 based on multi-wavelength observations. An oscillation is first detected at the top of MFR3 during 00:10-00:30 UT as triggered by an X5.4 flare-related eruption of an MFR (named "MFR1" here) in AR 11429. Then, after a quiet period of similar to 20 minutes at around 00:52 UT, external magnetic reconnection (EMR) occurred above MFR3 manifested by not only bidirectional outflow in extreme ultraviolet images, but also microwave quasi-periodic pulsation in broadband radio spectral observations for the first time. With the occurrence of EMR, the large-scale MFR3 quickly erupted at 01:01 UT and triggered an X1.3 flare, which is related to the eruption of the other MFR (named "MFR2" here) in AR 11429 at 01:05 UT. The erupting MFR3 and MFR2 appeared successively in the same associated halo coronal mass ejection (CME) as two different core structures. The identification of the large-scale MFR3 between two separated ARs and its complex activity may shed new light on our understanding of the initiation mechanism of a CME. Further work should lay emphasis on how a large-scale MFR3 forms in the solar atmosphere.