Properties of the first-order Fermi acceleration in fast magnetic reconnection driven by turbulence in collisional magnetohydrodynamical flows

Autor(es)

del Valle, Maria V. ; de Gouveia Dal Pino, E. M. ; Kowal, G.

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 463, n. 4, p. 4331-4343, DEC 2016.
• Citações Web of Science: 10

Resumo

Fast magnetic reconnection can occur in different astrophysical sources, producing flare-like emission and particle acceleration. Currently, this process is being studied as an efficient mechanism to accelerate particles via a first-order Fermi process. In this paper, we analyse the acceleration rate and the energy distribution of test particles injected into three-dimensional magnetohydrodynamical (MHD) domains with large-scale current sheets where reconnection is made fast by the presence of turbulence. We study the dependence of the particle acceleration time with the relevant parameters of the embedded turbulence: the Alfven speed V-A, the injection power P-inj and scale k(inj) (k(inj) = 1/l(inj)). We find that the acceleration time follows a power-law dependence with the particle kinetic energy: tacc. Ea, with 0.2 < alpha < 0.6 for a vast range of values of c/V-A similar to 20-1000. The acceleration time decreases with the Alfven speed (and therefore with the reconnection velocity) as expected, having an approximate dependence t(acc) proportional to (V-A/c)(-kappa), with kappa similar to 2.1-2.4 for particles reaching kinetic energies between 1 and 100 m(p)c(2), respectively. Furthermore, we find that the acceleration time is only weakly dependent on the P-inj and l(inj) parameters of the turbulence. The particle spectrum develops a high-energy tail, which can be fitted by a hard power law already in the early times of the acceleration, consistent with the results of kinetic studies of particle acceleration by magnetic reconnection in collisionless plasmas. (AU)

• Processo FAPESP: 13/04073-2 - Reconexão magnética e processos relacionados em plasmas astrofísicos colisionais e acolisionais: das chamas solares para fontes extragaláticas
• Beneficiário: Grzegorz Kowal
• Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores
• Processo FAPESP: 09/54006-4 - Um cluster de computadores para o Departamento de Astronomia do IAG-USP e para o Núcleo de Astrofísica da UNICSUL
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Linha de fomento: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 13/10559-5 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, simulações numéricas, observações e desenvolvimento de instrumentação para o Cherenkov Telescope Array (CTA)
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Linha de fomento: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/18815-0 - Reconexão magnética e processos relacionados em plasmas astrofísicos colisionais e acolisionais: das chamas solares para fontes extragaláticas
• Beneficiário: Grzegorz Kowal
• Linha de fomento: Bolsas no Brasil - Apoio a Jovens Pesquisadores