A Multi-Event Study of Early-Stage SEP Acceleration by CME-Driven Shocks—Sun to 1 AU

Kamen Kozarev,Rositsa Miteva,Momchil Dechev,Mohamed Nedal,Pietro Zucca

doi:10.3389/fspas.2022.801429

Abstract

The solar corona between below 10 solar radii is an important region for early acceleration and transport of solar energetic particles (SEPs) by coronal mass ejection-driven shock waves. There, these waves propagate into a highly variable dynamic medium with steep gradients and rapidly expanding coronal magnetic fields, which modulates the particle acceleration near the shock/wave surfaces, and the way SEPs spread into the heliosphere. We present a study modeling the acceleration of SEPs in global coronal shock events in the corona, as well as their transport to 1 au, based on telescopic observations coupled with dynamic physical models. As part of the project Solar Particle Radiation Environment Analysis and Forecasting—Acceleration and Scattering Transport (SPREAdFAST), we model the interaction of observed off-limb coronal bright fronts (CBF) with the coronal plasma from synoptic magnetohydrodynamic (MHD) simulations. We then simulate the SEP acceleration in analytical diffusive shock acceleration (DSA) model. The simulated fluxes are used as time-dependent inner boundary conditions for modeling the particle transport to 1 au. Resulting flux time series are compared with 1 au observations for validation. We summarize our findings and present implications for nowcasting SEP acceleration and heliospheric connectivity.

Highlights

One of the most common manifestations of solar activity are coronal mass ejections (CMEs)
We find that the density jump based on the differential emission measure (DEM) modeling within the AIA field of view is generally quite small, predominantly below 1.2, which is consistent with many previous studies (Kozarev et al, 2015; Vanninathan et al, 2015)
We have presented the first of its kind multi-event study of detailed physics-based Sun-to-1 au solar energetic particles (SEPs) simulations based on coronal diffusive shock acceleration and interplanetary propagation, of which we are aware

Summary

Introduction

One of the most common manifestations of solar activity are coronal mass ejections (CMEs) They are usually defined by observations in white light (Vourlidas et al, 2003; Zhang and Dere, 2006; Bein et al, 2011), but various aspects of these eruptions are observed in ultraviolet and radio wavelengths (Bastian et al, 2001; Veronig et al, 2010). CMEs may drive shock waves in the corona, if their propagation speeds exceed the local speed of information, usually the fast magnetosonic speed. Such shock waves are readily observed in EUV as so-called EUV waves (Thompson et al, 1998), known as coronal bright fronts [(Long et al, 2011), CBFs]. The bulk of the SEP acceleration was thought to occur in interplanetary space, Event date

Methods

Results

Conclusion