Acceleration of Electrons and Ions by an "Almost" Astrophysical Shock in the Heliosphere

Creators: Jebaraj, Immanuel Christopher; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Vuorinen, Laura; Gedalin, Michael; Choi, Kyung-Eun; Palmerio, Erika; Wijsen, Nicolas; Dresing, Nina; Cohen, Christina; Kouloumvakos, Athanasios; Balikhin, Michael; Vainio, Rami; Kilpua, Emilia; Afanasiev, Alexandr; Verniero, Jaye; Mitchell, John Grant; Trotta, Domenico; Hill, Matthew; Raouafi, Nour; Bale, Stuart D.

Abstract

Collisionless shock waves, ubiquitous in the Universe, are crucial for particle acceleration in various astrophysical systems. Currently, the heliosphere is the only natural environment available for their in situ study. In this work, we showcase the collective acceleration of electrons and ions by one of the fastest in situ shocks ever recorded, observed by the pioneering Parker Solar Probe at only 34.5 million km from the Sun. Our analysis of this unprecedented, near-parallel shock shows electron acceleration up to 6 MeV amidst intense multiscale electromagnetic wave emissions. We also present evidence of a variable shock structure capable of injecting and accelerating ions from the solar wind to high energies through a self-consistent process. The exceptional capability of the probe's instruments to measure electromagnetic fields in a shock traveling at 1% the speed of light has enabled us, for the first time, to confirm that the structure of a strong heliospheric shock aligns with theoretical models of strong shocks observed in astrophysical environments. This alignment offers viable avenues for understanding astrophysical shock processes and the self-consistent acceleration of charged particles.

Copyright and License

© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Funding

The Parker Solar Probe spacecraft was designed and built and is now operated by the Johns Hopkins Applied Physics Laboratory as part of NASA's Living with a Star (LWS) program (contract NNN06AA01C). Support from the LWS management and technical team has played a critical role in the success of the Parker Solar Probe mission. The authors express their gratitude to all the instrument teams for their work in processing and publishing the publicly available data from the Parker Solar Probe. All the data used in this study are from the Parker Solar Probe spacecraft. The data used in this study are available at the NASA Space Physics Data Facility (SPDF), https://spdf.gsfc.nasa.gov. This research was supported by the International Space Science Institute (ISSI) in Bern through ISSI International Team project No. 575, "Collisionless Shock as a Self-Regulatory System." I.C.J., N.D., and L.V. are grateful for support by the Academy of Finland (SHOCKSEE, grant No. 346902) and the European Union's Horizon 2020 research and innovation program under grant agreement No. 101004159 (SERPENTINE). O.V.A. was partially supported by NSF grant No. 1914670, NASA's Living with a Star (LWS) program (contract 80NSSC20K0218), and NASA grant contracts 80NNSC19K0848, 80NSSC22K0433, and 80NSSC22K0522. O.V.A. and V.V.K. were supported by NASA grants 80NSSC20K0697 and 80NSSC21K1770. V.V.K. also acknowledges financial support from CNES through grants "Parker Solar Probe" and "Solar Orbiter." L.V. acknowledges the financial support of the University of Turku Graduate School. E.P. acknowledges support from NASA's Parker Solar Probe Guest Investigators (PSP-GI; grant No. 80NSSC22K0349) program. N.W. acknowledges support from the Research Foundation—Flanders (FWO-Vlaanderen, fellowship No. 1184319N). A.K. acknowledges financial support from NASA NNN06AA01C (SO-SIS Phase-E, PSP EPI-Lo) contract. J.L.V. acknowledges support from NASA PSP-GI grant 80NSSC23K0208. The FIELDS experiment was developed and is operated under NASA contract NNN06AA01C.

Contributions

The study was initiated by I.C.J. and conceptualized together with O.V.A., V.V.K., and M.G. The methodologies for data analysis were provided by I.C.J., O.V.A., V.V.K., L.V., M.G., and E.P. Data analysis was performed by I.C.J., O.V.A., L.V., M.G., K.E.C., E.P., and A.K. The IS⊙IS data were processed by J.G.M., L.V., C.M.S.C., N.D., and A.K. The SPAN-i data were prepared by J.V. and analyzed by I.C.J., O.V.A., L.V., and K.E.C. The results were interpreted by I.C.J., O.V.A., V.V.K., M.G., and R.V. The data were visualized by I.C.J., O.V.A., L.V., and K.E.C. I.C.J. wrote the manuscript and prepared the final draft. The final draft was prepared taking into account extensive comments from O.V.A., V.V.K., M.G., M.B., N.D., R.V., E.K.J., and S.D.B. All authors have agreed to the results presented in the manuscript.

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