[P-EM37_30AM2] 磁気圏構造とダイナミクス

[PEM37-04] ディフューズオーロラに伴う相対論的電子降り込み

*栗田 怜¹、門倉 昭²、三好 由純³、佐藤 由佳²、三澤 浩昭¹、森岡 昭³ (1.東北大学大学院理学研究科、2.国立極地研究所、3.名古屋大学太陽地球環境研究所)

キーワード：ディフューズオーロラ, ホイッスラーモード波動, 波動粒子相互作用, 相対論的電子, 放射線帯

It has been widely thought that diffuse auroras are generated by electron precipitations in the energy range from a few keV to tens keV. Recent simulation results based on the quasi-linear theory showed that the scattering by whistler-mode waves plays an important role in the production of precipitating electrons responsible for diffuse auroras. A test particle simulation on electron- whistler interactions shows that relativistic electrons can be scattered into the loss cone simultaneously with the electrons in the energy range from a few keV to tens keV. Thus, it is expected that relativistic electrons precipitate into the atmosphere in association with diffuse auroras if whistler-mode waves contribute to generation of diffuse auroras. To examine this hypothesis, we investigated conjugate observations of SAMPEX and the all sky camera at Syowa Station on the dawn side, where diffuse auroras are frequently observed. In this study, we show a case study that relativistic electron (> 1 MeV) precipitations observed by SAMPEX are associated with the diffuse aurora observed at Syowa Station. The SAMPEX observation shows that the enhancement of precipitating relativistic electrons are well correlated with that of precipitating >150 keV electrons, indicating that electrons in the energy range from a few keV to 1 MeV precipitate into the atmosphere simultaneously. It is observational evidence that whistler mode waves contribute to generation of diffuse auroras.