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Amano T, Katou T, Kitamura N, Oka M, Matsumoto Y, Hoshino M, Saito Y, Yokota S, Giles BL, Paterson WR, Russell CT, Le Contel O, Ergun RE, Lindqvist PA, Turner DL, Fennell JF, Blake JB. Observational Evidence for Stochastic Shock Drift Acceleration of Electrons at the Earth's Bow Shock. PHYSICAL REVIEW LETTERS 2020; 124:065101. [PMID: 32109113 DOI: 10.1103/physrevlett.124.065101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/18/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidence for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale observations at the Earth's bow shock. The theoretical model can explain electron acceleration to mildly relativistic energies at high-speed astrophysical shocks, which may provide a solution to the long-standing issue of electron injection.
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Affiliation(s)
- T Amano
- Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan
| | - T Katou
- Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan
| | - N Kitamura
- Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan
| | - M Oka
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - Y Matsumoto
- Department of Physics, Chiba University, Chiba 263-8522, Japan
| | - M Hoshino
- Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Y Saito
- Institute of Space and Astronautical Science, Sagamihara 252-5210, Japan
| | - S Yokota
- Department of Earth and Space Science, Osaka University, Toyonaka 560-0043, Japan
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - W R Paterson
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - C T Russell
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA
| | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS/Ecole Polytechnique/Sorbonne Université/Univ. Paris-Sud/Obs. de Paris, Paris F-75252, France
| | - R E Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - P-A Lindqvist
- KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - D L Turner
- Space Sciences Department, The Aerospace Corporation, El Segundo, California 90245, USA
| | - J F Fennell
- Space Sciences Department, The Aerospace Corporation, El Segundo, California 90245, USA
| | - J B Blake
- Space Sciences Department, The Aerospace Corporation, El Segundo, California 90245, USA
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Matsumoto Y, Amano T, Kato TN, Hoshino M. Electron Surfing and Drift Accelerations in a Weibel-Dominated High-Mach-Number Shock. PHYSICAL REVIEW LETTERS 2017; 119:105101. [PMID: 28949173 DOI: 10.1103/physrevlett.119.105101] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Indexed: 06/07/2023]
Abstract
How electrons get accelerated to relativistic energies in a high-Mach-number quasiperpendicular shock is presented by means of ab initio particle-in-cell simulations in three dimensions. We found that coherent electrostatic Buneman waves and ion-Weibel magnetic turbulence coexist in a strong-shock structure whereby particles gain energy during shock surfing and subsequent stochastic drift accelerations. Energetic electrons that initially experienced the surfing acceleration undergo pitch-angle diffusion by interacting with magnetic turbulence and continuous acceleration during confinement in the shock transition region. The ion-Weibel turbulence is the key to the efficient nonthermal electron acceleration.
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Affiliation(s)
- Yosuke Matsumoto
- Department of Physics, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan,†
| | - Takanobu Amano
- Department of Earth and Planetary Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tsunehiko N Kato
- Center for Computational Astrophysics, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
| | - Masahiro Hoshino
- Department of Earth and Planetary Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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