Features of collisionless turbulence in the intracluster medium from simulated Faraday rotation maps – II. The effects of instabilities feedback
| Autor: | M. S. Nakwacki, G. Kowal, Diego Falceta-Gonçalves, E. M. de Gouveia Dal Pino, Reinaldo Santos-Lima |
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| Rok vydání: | 2016 |
| Předmět: |
Ciencias Físicas
NUMERICAL [METHODS] FOS: Physical sciences 01 natural sciences purl.org/becyt/ford/1 [https] symbols.namesake Thermal velocity Physics::Plasma Physics Intracluster medium MEIO INTERESTELAR 0103 physical sciences Faraday effect Magnetohydrodynamic drive 010306 general physics Anisotropy 010303 astronomy & astrophysics High Energy Astrophysical Phenomena (astro-ph.HE) Physics Turbulence Fluid Dynamics (physics.flu-dyn) Astronomy and Astrophysics Physics - Fluid Dynamics MAGNETIC FIELDS purl.org/becyt/ford/1.3 [https] Physics - Plasma Physics Magnetic field Computational physics Astronomía Plasma Physics (physics.plasm-ph) Classical mechanics Space and Planetary Science CLUSTERS: INTRACLUSTER MEDIUM [GALAXIES] Physics::Space Physics symbols TURBULENCE Magnetohydrodynamics Astrophysics - High Energy Astrophysical Phenomena CIENCIAS NATURALES Y EXACTAS |
| Zdroj: | CONICET Digital (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas instacron:CONICET Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | 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) analyzed 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 which considered a tensor pressure with uniform anisotropy. In the present 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 micro-scale 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 modeling the RM statistics in the ICM becomes better justified. Comment: 7 pages, 4 figures, accepted for publication on MNRAS |
| Databáze: | OpenAIRE |
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