A model of double coronal hard X-ray sources in solar flares
arXiv:2201.02293 · doi:10.3847/1538-4357/ac731b
Abstract
A number of double coronal X-ray sources have been observed during solar flares by RHESSI, where the two sources reside at different sides of the inferred reconnection site. However, where and how are these X-ray-emitting electrons accelerated remains unclear. Here we present the first model of the double coronal hard X-ray (HXR) sources, where electrons are accelerated by a pair of termination shocks driven by bi-directional fast reconnection outflows. We model the acceleration and transport of electrons in the flare region by numerically solving the Parker transport equation using velocity and magnetic fields from the macroscopic magnetohydrodynamic simulation of a flux rope eruption. We show that electrons can be efficiently accelerated by the termination shocks and high-energy electrons mainly concentrate around the two shocks. The synthetic HXR emission images display two distinct sources extending to 100 keV below and above the reconnection region, with the upper source much fainter than the lower one. The HXR energy spectra of the two coronal sources show similar spectral slopes, consistent with the observations. Our simulation results suggest that the flare termination shock can be a promising particle acceleration mechanism in explaining the double-source nonthermal emissions in solar flares.
Accepted for publication in ApJ
References in corpus (21)
- Non-Thermal Electron Acceleration in Low Mach Number Collisionless Shocks. I. Particle Energy Spectra and Acceleration Mechanism
- Measurement of magnetic field and relativistic electrons along a solar flare current sheet
- Global Energetics of Solar Flares: V. Energy Closure in Flares and Coronal Mass Ejections
- Double Coronal Hard and Soft X-ray Source Observed by RHESSI: Evidence for Magnetic Reconnection and Particle Acceleration in Solar Flares
- Electron Acceleration during Macroscale Magnetic Reconnection
- Above-the-loop-top Oscillation and Quasi-periodic Coronal Wave Generation in Solar Flares
- Formation of Power-law Electron Energy Spectra in Three-dimensional Low- Magnetic Reconnection
- Magnetohydrodynamic shocks in and above post-flare loops: two-dimensional simulation and a simplified model
- Magnetic Reconnection During the Post-Impulsive Phase of a Long-Duration Solar Flare: Bi-Directional Outflows as a Cause of Microwave and X-ray Bursts
- Thermal-nonthermal energy partition in solar flares derived from X-ray, EUV, and bolometric observations
- Quasi-periodic oscillations in flares and coronal mass ejections associated with magnetic reconnection
- The Acceleration and Confinement of Energetic Electrons by a Termination Shock in a Magnetic Trap: An Explanation for Nonthermal Loop-top Sources during Solar Flares
- A fully self-consistent model for solar flares
- The acceleration of high-energy protons at coronal shocks: the effect of large-scale streamer-like magnetic field structures
- Energetic Electron Distribution of the Coronal Acceleration Region: First results from Joint Microwave and Hard X-ray Imaging Spectroscopy
- Numerical examination of plasmoid-induced reconnection model for solar flares: the relation between plasmoid velocity and reconnection rate
- Radio Spectroscopic Imaging of a Solar Flare Termination Shock: Split-Band Feature as Evidence for Shock Compression
- Double Coronal X-ray and Microwave Sources Associated With A Magnetic Breakout Solar Eruption
- Radio Spectral Imaging of an M8.4 Eruptive Solar Flare: Possible Evidence of a Termination Shock
- Dynamical modulation of solar flare electron acceleration due to plasmoid-shock interactions in the looptop region
- Annihilation of Magnetic Islands at the Top of Solar Flare Loops