Features of collisionless turbulence in the intracluster medium from simulated Faraday rotation maps - II. The effects of instabilities feedback

Autor(es)

Santos-Lima, R. ; Dal Pino, E. M. de Gouveia ; Falceta-Goncalves, D. A. ; Nakwacki, M. S. ; Kowal, G.

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 465, n. 4, p. 4866-4871, MAR 2017.
• Citações Web of Science: 5

Resumo

Statistical analysis of Faraday rotation measure (RM) maps of the intracluster medium (ICM) of galaxy clusters provides a unique tool to evaluate some spatial features of the magnetic fields there. Its combination with numerical simulations of magnetohydrodynamic (MHD) turbulence allows the diagnosis of the ICM turbulence. Being the ICM plasma weakly collisional, the thermal velocity distribution of the particles naturally develops anisotropies as a consequence of the large-scale motions and the conservation of the magnetic moment of the charged particles. A previous study (Paper I) analysed the impact of large-scale thermal anisotropy on the statistics of RM maps synthesized from simulations of turbulence; these simulations employed a collisionless MHD model that considered a tensor pressure with uniform anisotropy. In this work, we extend that analysis to a collisionless MHD model in which the thermal anisotropy develops according to the conservation of the magnetic moment of the thermal particles. We also consider the effect of anisotropy relaxation caused by the microscale mirror and firehose instabilities. We show that if the relaxation rate is fast enough to keep the anisotropy limited by the threshold values of the instabilities, the dispersion and power spectrum of the RM maps are indistinguishable from those obtained from collisional MHD. Otherwise, there is a reduction in the dispersion and steepening of the power spectrum of the RM maps (compared to the collisional case). Considering the first scenario, the use of collisional MHD simulations for modelling the RM statistics in the ICM becomes better justified. (AU)

• Processo FAPESP: 13/15115-8 - Estudo de efeitos de plasma não-colisional: aplicação ao meio intra-aglomerado de galáxias
• Beneficiário: Reinaldo Santos de Lima
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• 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
• Modalidade de apoio: Auxílio à Pesquisa - Projetos Especiais
• 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
• Modalidade de apoio: Bolsas no Brasil - Jovens Pesquisadores
• 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
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores