Non-thermal Electrons at Quasi-Perpendicular Shocks: Statistical Properties and the Whistler Critical Mach Number

Oka, M.(1), T. Terasawa(2), Y. Seki(1), Y. Kasaba(1), H. Kojima(3), H. Matsui(4), M. Fujimoto(5), H. Matsumoto(3), Y. Saito(1), and T. Mukai(1)

(1)ISAS, Japan Aerospace Exploration Agency
(2)The University of Tokyo
(3)RISH, Kyoto University
(4)University of New Hampshire
(5)Tokyo Institute of Technology

It has theoretically been expected that whistler waves are emitted upstream of shocks whenever Mach number falls below a critical Mach number. By performing statistical analysis of the upstream waves, we have observational evidenced the `whistler critical Mach number' at the Earth's bow shock using the GEOTAIL spacecraft. We have further found that the critical Mach number regulates electron acceleration. The obtained result suggests different acceleration mechanism for below and above the critical Mach number. We will apply the results to the loop-top environment of solar flares and discuss on possible acceleration mechanisms.

Correspondence

Mitsuo Oka (moka@kwasan.kyoto-u.ac.jp), Kwasan Observatory, Kyoto University

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