The Source of Energetic Storm Particles for the 2023 March 13 Event Observed by Parker Solar Probe
Year: 2025
Type: article
Abstract: On 2023 March 13, Parker Solar Probe was located about 0.23 au from the Sun when it was crossed by a very fast interplanetary shock. The intensities of ∼0.08–10 MeV energetic protons were markedly enhanced at the shock crossing. At energies from ∼0.1 to 1 MeV, the intensity at the shock was 3–4 orders of magnitude larger than it was ∼4 hr prior. In this study, we investigate the possible source of particles that led to this enhancement. Pre-existing high-energy particles that were present during the few-hour period prior to the shock could possibly serve as a source, assuming they are accelerated to even higher energies by the shock. We apply a “seeds test”—which determines the expected enhancement at the shock—to test this. We find that none of the pre-existing particle populations identified can account for the observed enhancement at the shock. The solar wind itself provides a very abundant source. To test whether shock-heated thermal solar wind could account for the source, we perform a series of self-consistent hybrid plasma simulations of this event and make direct comparisons with the observed particle spectra and magnetic field. We conclude that shock-heated solar wind protons are the source of energetic particles in this event. The direct comparisons of our simulations and observations also suggest that the shock was moving about 1350 km s −1 and had an Alfvén Mach number of about 4, both of which are considerably lower than previously estimated.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: Collaborative Research: Transport Processes Affecting High-Energy Solar Energetic Particles Observed at Earth, THE PARTICLE ACCELERATION AT INTERPLANETARY SHOCKS HAS BEEN AN ACTIVE FIELD OF OBSERVATIONAL AND THEORETICAL INVESTIGATION IN THE PAST FIVE DECADES; HOWEVER THE SPATIAL DISTRIBUTION OF ENERGETIC PARTICLES ACROSS THE SHOCK CAN NOT BE REPRODUCED BY CURRENT THEORETICAL MODELS IN SEVERAL CASES. WE PROPOSE TO INVESTIGATE THE LOCAL INTENSITY ENHANCEMENTS AT THE SHOCK (SO-CALLED "SPIKES") OF SUPRA-THERMAL PARTICLES HAVING A SPEED WITHIN ONE ORDER OF MAGNITUDE GREATER THAN THE SHOCK SPEED IN THE UPSTREAM FLUID REST FRAME. THIS REGIME HOLDS BEYOND THE VALIDITY OF THE STANDARD DIFFUSIVE SHOCK ACCELERATION MODEL AND HAS BEEN POORLY STUDIED SO FAR. WE CONSIDER THIS WORK AN OVERDUE AND INNOVATIVE APPROACH TO THE SO-CALLED "INJECTION PROBLEM". WE PROPOSE A DATA-GUIDED STUDY TO COMBINE: 1) ANALYSIS AND INTERPRETATION OF INTERPLANETARY SHOCKS HIGH TIME RESOLUTION DATA COLLECTED BY ENERGETIC PARTICLE DETECTORS AND MAGNETOMETERS AT 1 AU ONBOARD ACE (ADVANCED COMPOSITION EXPLORER) AND STEREO (SOLAR TERRESTRIAL RELATIONS OBSERVATORY) A/B; 2) THEORY AND ADVANCED NUMERICAL SIMULATIONS AT SHOCKS PROPAGATING IN A TURBULENT MEDIUM TO INTERPRET THE AVAILABLE DATA. AN ANALYSIS RECENTLY CONDUCTED HAS SUGGESTED THAT THE OBSERVED ANISOTROPY AT SHOCK SPIKES RESULTS FROM BIDIRECTIONAL STREAMING OF IONS ALONG FIELD LINES THAT CROSS THE SHOCK MULTIPLE TIMES AT ODDS WITH A PREVIOUS INTERPRETATION BASED ON PILE-UP OF REFLECTED IONS; WE WILL COMPARE SUCH INTERPRETATIONS IN DETAIL. WE HAVE IDENTIFIED TWO CASES OF SHOCK SPIKE THAT WE WILL ANALYZE IN DETAIL AND WE WILL LOOK FOR OTHER CASES FROM EXISTING AND UPCOMING SPACECRAFT ARCHIVES. WE WILL COMPARE THOSE DATA WITH OUR MULTIPLE-APPROACH SIMULATIONS TO INVESTIGATE THE ORIGIN OF THE SHOCK SPIKES THEIR ANISOTROPY AND TIME-EVOLUTION., G492110738, G5966779717, G805766356, G8457443216
OpenAlex ID: W7117665139