The Role of 3D Reconnection in the Escape of Impulsive SEPs
Abstract
It is widely accepted that impulsive solar energetic particle (SEP) events are due to the escape into the interplanetary medium of flare-accelerated particles produced by solar eruptive events. According to the standard solar eruption model, however, particles accelerated by flare reconnection should remain trapped in the closed field lines of the flare loops and the flux rope comprising the coronal mass ejection. To resolve this paradox, we performed fully 3D high-resolution MHD simulations of a CME/eruptive flare in a coronal system that consists of a bipolar active region embedded in a background global dipole field structured by solar wind. Our simulations show that multiple magnetic reconnection episodes occur prior to and during the CME eruption and its interplanetary propagation. In addition to the episodes that build up the flux rope, reconnection between the open field and the CME couples the closed corona to the open interplanetary field. Flare-accelerated particles initially trapped in the CME thereby gain access to the open interplanetary field along a trail blazed by magnetic reconnection. A key difference between these 3D results and our previous 2.5D calculations is that the interchange reconnection allows accelerated particles to escape from deep within the CME flux rope. We estimate the spatial extent of the particle-escape channels. The relative timings between flare acceleration and release of the energetic particles through CME/open-field coupling are also determined. We discuss the implications of these results for Parker Solar Probe and Solar Orbiter observations. This work was supported by the NASA Living with a Star Program.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1004A