Whistler critical Mach number and electron acceleration at the bow shock: Geotail observation

M. Oka, T. Terasawa, Y. Seki, M. Fujimoto, Y. Kasaba, H. Kojima, I. Shinohara, H. Matsui, H. Matsumoto, Y. Saito, T. Mukai

研究成果: Article査読

48 被引用数 (Scopus)

抄録

The 'whistler critical Mach number', Mcrit,w is one of the dimensionless parameters that characterizes collisionless shocks. Originally, it was introduced to indicate the critical point above which whistler waves do not propagate upstream. Indeed our analysis of Geotail data at the Earth's bow shock shows intense whistler waves in the sub-critical regime, MA < Mcritw but not in the super-critical regime. In this paper, we further report that Mcritw seems to regulate the electron acceleration efficiency at the shocks. At the shock transition layer it is found that the spectral index Γ of electron energy spectra defined by F(E) ∝ E-Γ is distributed between 3.5 and 5.0 in the sub-critical regime, while the hardest energy spectra with Γ = 3-3.5 are detected in the super-critical regime. We discuss a possible relationship between Mcritw and the electron acceleration.

本文言語English
論文番号L24104
ジャーナルGeophysical Research Letters
33
24
DOI
出版ステータスPublished - 2006 12 28
外部発表はい

ASJC Scopus subject areas

  • 地球物理学
  • 地球惑星科学(全般)

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