Evidence of Time-Dependent Diffusive Shock Acceleration in the 2022 September 5 Solar Energetic Particle Event
arXiv:2506.20322 · doi:10.3847/1538-4357/ae1227
Abstract
On 2022 September 5, a large solar energetic particle (SEP) event was detected by Parker Solar Probe (PSP) and Solar Orbiter (SolO), at heliocentric distances of 0.07 and 0.71 au, respectively. PSP observed an unusual velocity-dispersion signature: particles below 1 MeV exhibited a normal velocity dispersion, while higher-energy particles displayed an inverse velocity arrival feature, with the most energetic particles arriving later than those at lower energies. The maximum energy increased from about 20-30 MeV upstream to over 60 MeV downstream of the shock. The arrival of SEPs at PSP was significantly delayed relative to the expected onset of the eruption. In contrast, SolO detected a typical large SEP event characterized by a regular velocity dispersion at all energies up to 100 MeV. To understand these features, we simulate particle acceleration and transport from the shock to the observers with our newly developed SEP model - Particle ARizona and MIchigan Solver on Advected Nodes (PARMISAN). Our results reveal that the inverse velocity arrival and delayed particle onset detected by PSP originate from the time-dependent diffusive shock acceleration processes. After shock passage, PSP's magnetic connectivity gradually shifted due to its high velocity near perihelion, detecting high-energy SEPs streaming sunward. Conversely, SolO maintained a stable magnetic connection to the strong shock region where efficient acceleration was achieved. These results underscore the importance of spatial and temporal dependence in SEP acceleration at interplanetary shocks, and provide new insights to understand SEP variations in the inner heliosphere.
References in corpus (23)
- The Solar Orbiter mission -- Science overview
- Alfven Wave Solar Model (AWSoM): Coronal Heating
- Advancements in the ADAPT Photospheric Flux Transport Model
- MHD Waves and Coronal Heating: Unifying Empirical and MHD Turbulence Models
- A semi-analytical approach to non-linear shock acceleration
- Solar-MACH: An open-source tool to analyze solar magnetic connection configurations
- What Sustained Multi-Disciplinary Research Can Achieve: The Space Weather Modeling Framework
- Obtaining Potential Field Solution with Spherical Harmonics and Finite Differences
- Data Constrained Coronal Mass Ejections in A Global Magnetohydrodynamics Model
- Extended MHD modeling of the steady solar corona and the solar wind
- Chromosphere to 1 AU Simulation of the 2011 March 7th Event: A Comprehensive Study of Coronal Mass Ejection Propagation
- Validation of the Alfvén Wave Solar atmosphere Model (AWSoM) with Observations from the Low Corona to 1 AU
- Particle acceleration by collisionless shocks containing large-scale magnetic-field variations
- The acceleration of high-energy protons at coronal shocks: the effect of large-scale streamer-like magnetic field structures
- Correcting for interplanetary scattering in velocity dispersion analysis of solar energetic particles
- Magnetic Field Line Random Walk and Solar Energetic Particle Path Lengths: Stochastic Theory and PSP/ISoIS Observation
- A global model of particle acceleration at pulsar wind termination shocks
- The effect of the ambient solar wind medium on a CME-driven shock and the associated gradual solar energetic particle event
- Eruptive Event Generator Based on the Gibson-Low Magnetic Configuration
- Solar Energetic Particle Acceleration at a Spherical Shock with the Shock Normal Angle Evolving in Space and Time
- Shock and SEP Modeling Study for the 5 September 2022 SEP Event
- Investigation of Inverse Velocity Dispersion in a Solar Energetic Particle Event Observed by Solar Orbiter
- Physics-Based Simulation of the 2013 April 11 Solar Energetic Particle Event