Quasiperiodic acceleration of electrons by a plasmoid-driven shock in the solar atmosphere

TL;DR

This study demonstrates that plasmoid-driven shocks in the solar atmosphere can cause quasi-periodic acceleration of electrons, linking CME eruptions with energetic particle production through detailed multi-wavelength observations.

Contribution

It provides new observational evidence that plasmoid-driven shocks can produce periodic electron acceleration, enhancing understanding of particle acceleration mechanisms in solar eruptions.

Findings

CME-induced shock was coincident with a coronal wave and radio burst.

Electrons were intermittently accelerated to energies of 2-46 keV.

Quasi-perpendicular shocks can produce quasi-periodic electron acceleration.

Abstract

Cosmic rays and solar energetic particles may be accelerated to relativistic energies by shock waves in astrophysical plasmas. On the Sun, shocks and particle acceleration are often associated with the eruption of magnetized plasmoids, called coronal mass ejections (CMEs). However, the physical relationship between CMEs and shock particle acceleration is not well understood. Here, we use extreme ultraviolet, radio and white-light imaging of a solar eruptive event on 22 September 2011 to show that a CME-induced shock (Alfv\'en Mach number 2.4$^{+0.7}_{-0.8}$) was coincident with a coronal wave and an intense metric radio burst generated by intermittent acceleration of electrons to kinetic energies of 2-46 keV (0.1-0.4 c). Our observations show that plasmoid-driven quasi-perpendicular shocks are capable of producing quasi-periodic acceleration of electrons, an effect consistent with a turbulent or rippled plasma shock surface.