Japan Geoscience Union Meeting 2016

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International Session (Poster)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM06] Magnetospheric Multi-Scale (MMS) mission -- A new age of magnetospheric physics

Tue. May 24, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Seiji Zenitani(National Astronomical Observatory of Japan), Naritoshi Kitamura(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Yoshifumi Saito(Solar System Science Division, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Paul Cassak(West Virginia University), Li-Jen Chen(NASA Goddard Space Flight Center), Craig Pollock(NASA Goddard Space Flight Center)

5:15 PM - 6:30 PM

[PEM06-P02] Electron acceleration at the Earth's quasi-perpendicular bow shock: MMS observation

*Mitsuo Oka1, Tai Phan1, Arthur Hull1, Jim Burch2, Roy Torbert3, Craig Pollock4, Daniel Gershman5, Barbara Giles5 (1.UC Berkeley, 2.SwRI, 3.Univ. New Hampshire, 4.Denali Scientific, 5.NASA GSFC)

Keywords:particle acceleration, shock, non-thermal, MMS, electron

Electrons can be accelerated to non-thermal energies (> 1 keV) at interplanetary shocks and the Earth's bow shock. While simulation studies have proposed various mechanisms, the precise mechanism of electron acceleration remains unclear. Here we show, based on the ultra high-time resolution measurements by MMS, that electrons form a power-law energy spectrum at and around the shock ramp region. The signatures of non-thermal electrons are modulated by the periodic variations of the shock internal structure at the time scale of roughly ion gyro period. In an event of high Mach number (~11) quasi-perpendicular shock crossing (shock angle ~ 80 degrees), we found that there exists an upper energy-limit (cutoff) in the power-law spectrum at ~10 keV and that the electron gyro-radius of this energy is roughly equal to the local ion inertial length, consistent with the idea of acceleration within the narrow shock ramp region. In this presentation, we will further discuss possible mechanisms of electron acceleration by, for example, gradient B drift and stochastic processes via waves.