MAGNETOHYDRODYNAMIC SIMULATIONS OF RECONNECTION AND PARTICLE ACCELERATION: THREE-DIMENSIONAL EFFECTS

Autor(es)

Kowal, Grzegorz ^{[1, 2]} ; Dal Pino, E. M. de Gouveia ^[1] ; Lazarian, A. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil

^[2] Uniwersystet Jagiellonski, Obserwatorium Astron, PL-30244 Krakow - Poland

^[3] Univ Wisconsin, Dept Astron, Madison, WI 53706 - USA

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 735, n. 2 JUL 10 2011.
• Citações Web of Science: 76

Resumo

Magnetic fields can change their topology through a process known as magnetic reconnection. This process in not only important for understanding the origin and evolution of the large-scale magnetic field, but is seen as a possibly efficient particle accelerator producing cosmic rays mainly through the first-order Fermi process. In this work we study the properties of particle acceleration inserted in reconnection zones and show that the velocity component parallel to the magnetic field of test particles inserted in magnetohydrodynamic (MHD) domains of reconnection without including kinetic effects, such as pressure anisotropy, the Hall term, or anomalous effects, increases exponentially. Also, the acceleration of the perpendicular component is always possible in such models. We find that within contracting magnetic islands or current sheets the particles accelerate predominantly through the first-order Fermi process, as previously described, while outside the current sheets and islands the particles experience mostly drift acceleration due to magnetic field gradients. Considering two-dimensional MHD models without a guide field, we find that the parallel acceleration stops at some level. This saturation effect is, however, removed in the presence of an out-of-plane guide field or in three-dimensional models. Therefore, we stress the importance of the guide field and fully three-dimensional studies for a complete understanding of the process of particle acceleration in astrophysical reconnection environments. (AU)

• Processo FAPESP: 06/50654-3 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, observação e simulações numéricas
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 09/50053-8 - Magnetic reconnection and particle acceleration in astrophysical sources and diffuse media
• Beneficiário: Grzegorz Kowal
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado