Particle Acceleration in Turbulence and Weakly Stochastic Reconnection

Autor(es)

Kowal, Grzegorz ^[1] ; de Gouveia Dal Pino, Elisabete M. ^[1] ; Lazarian, A. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo - Brazil

^[2] Univ Wisconsin, Dept Astron, Madison, WI 53706 - USA

• Tipo de documento: Artigo Científico
• Fonte: Physical Review Letters; v. 108, n. 24, p. 241102, 2012.
• Citações Web of Science: 49

Resumo

In this Letter we analyze the energy distribution evolution of test particles injected in three dimensional (3D) magnetohydrodynamic (MHD) simulations of different magnetic reconnection configurations. When considering a single Sweet-Parker topology, the particles accelerate predominantly through a first-order Fermi process, as predicted in [3] and demonstrated numerically in [8]. When turbulence is included within the current sheet, the acceleration rate is highly enhanced, because reconnection becomes fast and independent of resistivity [4,11] and allows the formation of a thick volume filled with multiple simultaneously reconnecting magnetic fluxes. Charged particles trapped within this volume suffer several head-on scatterings with the contracting magnetic fluctuations, which significantly increase the acceleration rate and results in a first-order Fermi process. For comparison, we also tested acceleration in MHD turbulence, where particles suffer collisions with approaching and receding magnetic irregularities, resulting in a reduced acceleration rate. We argue that the dominant acceleration mechanism approaches a second order Fermi process in this case. (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