Dynamical small-scale magnetic islands as a source of local acceleration of particles in the solar wind

[摘要] We present observations of energetic particle flux increases up to 1 MeV at 1 AU, which cannot be associated with ordinary mechanisms of particle acceleration, such as acceleration at shocks or at the Sun. Such unusual energetic particle events very likely have a local origin. Multi-spacecraft observations show that numerous cases of energetic particle flux enhancements and spikes correspond to passages of spacecraft through areas filled with magnetic islands with a typical width ∼0.01-0.001AU that experience dynamical merging or/and contraction. The presence of magnetic islands inside magnetically confined cavities in the solar wind may lead to local particle energization, especially in the case when the particles have already been pre-accelerated to keV energies, for example, at shocks or due to magnetic reconnection at the heliospheric current sheet. We consider different magnetic configurations that provide favourable conditions for both the appearance of small-scale magnetic islands and their confinement.

[发布机构] Heliophysical Laboratory, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation RAS (IZMIRAN), Troitsk, Moscow; 142190, Russia^1;Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville; AL; 35805, United States^2;Department of Space Science, University of Alabama in Huntsville, Huntsville; AL; 35899, United States^3;IAASARS, National Observatory of Athens, Penteli; GR-15236, Greece^4;Department of Mathematics and Information Sciences, Northumbria University, Newcastle upon Tyne; NE2 1XE, United Kingdom^5

[效力级别] 天文学 [学科分类] 天文学(综合)

[关键词] Acceleration of particles;Energetic particle events;Energetic particle flux;Heliospheric current sheet;Magnetic configuration;Magnetic reconnections;Particle acceleration;Spacecraft observations