On the Ubiquity of Magnetic Reconnection inside Flux Transfer Events at the Earth's Magnetopause
Abstract
Flux Transfer Events (FTEs) are transient phenomena regularly observed at the Earth's magnetopause. Their classical signatures are (1) an increase in their core magnetic field strength and (2) a bipolar signature in the component normal to the magnetopause. The usual interpretation is a rope of magnetic field lines moving away from the reconnection region. However, some observations do not fit this configuration. The Magnetospheric Multiscale mission (MMS) provides new insights for these events thanks to unprecedented temporal and spatial resolution. Its measurements reveal that magnetic reconnection can occur in the core of FTEs, questioning the flux rope configuration with regular helicoidal structure. In this work we investigate over 135 FTEs identified from September 2015 to March 2016, and find that magnetic reconnection occurs in their core for 24% of them. Subsequently, two categories of FTEs are distinguished and analyzed separately. Also, analysis of the parallel heat flux, which contains information on the pitch angle distributions of supra-thermal electrons and the large-scale magnetic topology, is typically different between the first and second parts of the reconnecting FTEs. When computing the heat flux difference between the leading and trailing parts of the structure, independently for both groups, we find that it is higher for reconnecting FTEs than for regular flux rope FTEs. We also investigate the FTE formation conditions and find that the Interplanetary Magnetic Field (IMF) is mainly oriented southward and with a strong By component prior to the observed FTEs with core reconnection. Based on these results, a model involving multiple X-line reconnection at the dayside magnetopause is proposed, wherein the large By in the IMF permits the formation of a bifurcated X-line at the magnetopause that would allow the formation of complex interlaced flux tubes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSM32A..04F
- Keywords:
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- 7835 Magnetic reconnection;
- SPACE PLASMA PHYSICS;
- 7845 Particle acceleration;
- SPACE PLASMA PHYSICS;
- 7863 Turbulence;
- SPACE PLASMA PHYSICS;
- 7867 Wave/particle interactions;
- SPACE PLASMA PHYSICS