Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients
Shock waves are sites of intense plasma heating and charged particle acceleration. In collisionless solar wind plasmas, such acceleration is attributed to shock drift or Fermi acceleration but also to wave–particle resonant interactions. We examine the latter for the case of electrons interacting wi...
| Main Authors: | , , , , |
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| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acd9ab |
| _version_ | 1797698914973908992 |
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| author | Xiaofei Shi Anton Artemyev Vassilis Angelopoulos Terry Liu Xiao-Jia Zhang |
| author_facet | Xiaofei Shi Anton Artemyev Vassilis Angelopoulos Terry Liu Xiao-Jia Zhang |
| author_sort | Xiaofei Shi |
| collection | DOAJ |
| description | Shock waves are sites of intense plasma heating and charged particle acceleration. In collisionless solar wind plasmas, such acceleration is attributed to shock drift or Fermi acceleration but also to wave–particle resonant interactions. We examine the latter for the case of electrons interacting with one of the most commonly observed wave modes in shock environments, the whistler mode. Such waves are particularly intense in dynamic, localized regions upstream of shocks, arising from the kinetic interaction of the shock with solar wind discontinuities. These regions, known as foreshock transients, are also sites of significant electron acceleration by mechanisms not fully understood. Using in situ observations of such transients in the Earth’s foreshock, we demonstrate that intense whistler-mode waves can resonate nonlinearly with >25 eV solar wind electrons and accelerate them to ∼100–500 eV. This acceleration is mostly effective for the 50–250 eV energy range, where the accelerated electron population exhibits a characteristic butterfly pitch-angle distribution consistent with theoretical predictions. Such nonlinear resonant acceleration is very fast, implying that this mechanism may be important for injecting suprathermal electrons of solar wind origin into the shock region, where they can undergo further, efficient shock-drift acceleration to even higher energies. |
| first_indexed | 2024-03-12T04:01:00Z |
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| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:01:00Z |
| publishDate | 2023-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj.art-cb3fdc1753fc4257bd97a8ea114f11742023-09-03T11:34:28ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195213810.3847/1538-4357/acd9abEvidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock TransientsXiaofei Shi0https://orcid.org/0000-0003-3367-5074Anton Artemyev1https://orcid.org/0000-0001-8823-4474Vassilis Angelopoulos2Terry Liu3https://orcid.org/0000-0003-1778-4289Xiao-Jia Zhang4Department of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, University of California , Los Angeles, CA, USA ; sxf1698@g.ucla.eduDepartment of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, University of California , Los Angeles, CA, USA ; sxf1698@g.ucla.edu; Space Research Institute of the Russian Academy of Sciences , Moscow 117997, RussiaDepartment of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, University of California , Los Angeles, CA, USA ; sxf1698@g.ucla.eduDepartment of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, University of California , Los Angeles, CA, USA ; sxf1698@g.ucla.eduDepartment of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, University of California , Los Angeles, CA, USA ; sxf1698@g.ucla.edu; Department of Physics, University of Texas at Dallas , Richardson, TX, USAShock waves are sites of intense plasma heating and charged particle acceleration. In collisionless solar wind plasmas, such acceleration is attributed to shock drift or Fermi acceleration but also to wave–particle resonant interactions. We examine the latter for the case of electrons interacting with one of the most commonly observed wave modes in shock environments, the whistler mode. Such waves are particularly intense in dynamic, localized regions upstream of shocks, arising from the kinetic interaction of the shock with solar wind discontinuities. These regions, known as foreshock transients, are also sites of significant electron acceleration by mechanisms not fully understood. Using in situ observations of such transients in the Earth’s foreshock, we demonstrate that intense whistler-mode waves can resonate nonlinearly with >25 eV solar wind electrons and accelerate them to ∼100–500 eV. This acceleration is mostly effective for the 50–250 eV energy range, where the accelerated electron population exhibits a characteristic butterfly pitch-angle distribution consistent with theoretical predictions. Such nonlinear resonant acceleration is very fast, implying that this mechanism may be important for injecting suprathermal electrons of solar wind origin into the shock region, where they can undergo further, efficient shock-drift acceleration to even higher energies.https://doi.org/10.3847/1538-4357/acd9abPlanetary bow shocks |
| spellingShingle | Xiaofei Shi Anton Artemyev Vassilis Angelopoulos Terry Liu Xiao-Jia Zhang Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients The Astrophysical Journal Planetary bow shocks |
| title | Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients |
| title_full | Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients |
| title_fullStr | Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients |
| title_full_unstemmed | Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients |
| title_short | Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients |
| title_sort | evidence of electron acceleration via nonlinear resonant interactions with whistler mode waves at foreshock transients |
| topic | Planetary bow shocks |
| url | https://doi.org/10.3847/1538-4357/acd9ab |
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