The origin of underdense plasma downflows associated with magnetic reconnection in solar flares

Chengcai Shen, Bin Chen, Katharine K. Reeves, Sijie Yu, Vanessa Polito, Xiaoyan Xie

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Magnetic reconnection is a universal process that powers explosive energy-release events such as solar flares, geomagnetic substorms and some astrophysical jets. A characteristic feature of magnetic reconnection is the production of fast reconnection outflow jets near the plasma Alfvén speeds1,2. In eruptive solar flares, dark finger-shaped plasma downflows moving toward the flare arcade have been commonly regarded as the principal observational evidence for such reconnection-driven outflows3,4. However, they often show a speed much slower than that expected in reconnection theories5,6, challenging the reconnection-driven energy-release scenario in standard flare models. Here we present a three-dimensional magnetohydrodynamics model of solar flares. By comparing the model predictions with the observed plasma downflow features, we conclude that these dark downflows are self-organized structures formed in a turbulent interface region below the flare termination shock where the outflows meet the flare arcade, a phenomenon analogous to the formation of similar structures in supernova remnants. This interface region hosts a myriad of turbulent flows, electron currents and shocks, crucial for flare energy release and particle acceleration.

Original languageEnglish (US)
Pages (from-to)317-324
Number of pages8
JournalNature Astronomy
Volume6
Issue number3
DOIs
StatePublished - Mar 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics

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