Energetic particles observed by Solar Orbiter associated with a sharp shock wave passage from the solar backside event of March 13-14, 2023

Acceleration of charged particles in solar flares, during reconnection of magnetic field lines in coronal loops, and by shock waves in the solar corona and interplanetary space are some of the substantial physical processes being studied by the Solar Orbiter mission. Cross-analysis of the light curves of the non-thermal parts of X-ray flares energy spectra registered by the Spectrometer Telescope for Imaging X-rays (STIX), and high-energy charged particle spectrograms recorded by the Energetic Particle Detector (EPD) suite assist us in furthering our understanding of these events.

The anomalies and events in interplanetary space such as shocks, CIRs, ICMEs, solar and interplanetary radio bursts, SEPs being investigated in situ regime are typically associated with solar X-ray flares and/or SDO/AIA measurements of the solar atmosphere in multiple wavelengths when sources are on the visible side of the solar disk. In cases where the powerful flare occurs on the Sun's backside, the massive CME can reach the volumes in the interplanetary space right at the opposite side of the CME’s seed and manifests in different forms of irregularities in the solar wind parameters and magnetic field components as well in enhanced energetic particle fluxes. Such types of occasions are of particular interest due to their near-global impact on the inner heliosphere.

In this study, we conduct a cross-analysis of the data derived from the Solar Wind Analyzer Proton-Alpha Sensor (SWA-PAS), Magnetometer (MAG), and EPD suite onboard the Solar Orbiter for the period of 13-14 March 2023, when a high-speed CME launched from near 180° from Earth accelerated an enormous quantity of high energy charged particles, from electrons to iron ions. At the time SolO was located 26°East of the Earth-Sun line at a distance of about 0.6 au. Even so, the CME quickly reached the spacecraft and manifested as a very sharp and strong shock at the front of which particles were accelerated additionally. In the analysis, we involve the data from the Suprathermal Ion Spectrograph (SIS), the SupraThermal Electrons and Protons (STEP), and the Electron Proton Telescope (EPT) of the EPD suite.

This work is supported by the “Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners”.