Dynamic acceleration of energetic protons by an interplanetary collisionless shock

作者：Liu Yang, V. Heidrich-Meisner, W. Wang, R. F. Wimmer‐Schweingruber, Linghua Wang, A. Kollhoff, L. Berger, D. Pacheco, Zigong Xu, J. Rodrı́guez-Pacheco, G. C. Ho · 发表于：Astronomy and Astrophysics · 年份：2024 · DOI：10.1051/0004-6361/202348723 · 被引用次数：14 · 研究领域：Solar and Space Plasma Dynamics、Gamma-ray bursts and supernovae、Ionosphere and magnetosphere dynamics

Context. Interplanetary collisionless shocks are known to be capable of accelerating charged particles up to hundreds of MeV. However, the underlying acceleration mechanisms are still under debate. Aims. We present the dynamic behaviors of energetic protons that are accelerated by an interplanetary shock that was observed with unprecedented high-resolution measurements by the Electron-Proton Telescope sensor of the Energetic Particle Detector suite on board the Solar Orbiter spacecraft on 2021 November 3. We constrain the potential acceleration mechanisms and processes. Methods. We first reconstructed the proton pitch-angle distributions (PADs) in the solar wind frame. Then, we examined the temporal flux profile, PAD, and the velocity distribution function of energetic protons close to the shock, and we qualitatively compared the observations with theoretical predictions. Moreover, we applied a velocity dispersion analysis (VDA) to an observed velocity dispersion event and derived the proton path length and release time at the shock. Then, we tested this derivation by comparing it with the shock motion and the magnetic field configuration. Results. We find that ∼1000–4000 keV protons exhibit a rapid-rise, rapid-decay temporal flux profile with a clear velocity dispersion ∼2 min before the shock, similar to impulsive solar energetic particle events. The proton path length based on the VDA of this event is consistent with the length derived from the shock motion and magnetic fi...