Features of collisionless turbulence in the intracluster medium from simulated Faraday Rotation maps

Author(s)

Nakwacki, M. S. ^{[1, 2]} ; Kowal, G. ^{[3, 4]} ; Santos-Lima, R. ^[5] ; de Gouveia Dal Pino, E. M. ^[5] ; Falceta-Goncalves, D. A. ^{[6, 3]}

Affiliation

^[1] Univ Buenos Aires, Fac Ciencias Exactas & Nat, RA-1053 Buenos Aires, DF - Argentina

^[2] UBA CONICET, Inst Astron & Fis Espacio, Buenos Aires, DF - Argentina

^[3] Univ Sao Paulo, Escola Artes Ciencias & Humanidades, Sao Paulo, SP - Brazil

^[4] Univ Cruzeiro Sul, Nucleo Astrofs Ter, Sao Paulo, SP - Brazil

^[5] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo, SP - Brazil

^[6] Univ St Andrews, Sch Phys & Astron, SUPA, St Andrews KY16 9SS, Fife - Scotland

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 455, n. 4, p. 3702-3723, FEB 1 2016.
• Web of Science Citations: 4

Abstract

Observations of the intracluster medium (ICM) in galaxy clusters suggest for the presence of turbulence and the magnetic fields' existence has been proved through observations of Faraday Rotation (FR) and synchrotron emission. The ICM is also known to be filled by a rarefied weakly collisional plasma. In this work, we study the possible signatures left on FR maps by collisionless instabilities. For this purpose, we use a numerical approach to investigate the dynamics of the turbulence in collisionless plasmas based on an magnetohydrodynamical (MHD) formalism taking into account different levels of pressure anisotropy. We consider models covering the sub/super-Alfvenic and trans/supersonic regimes, one of them representing the fiducial conditions corresponding to the ICM. From the simulated models, we compute FR maps and analyse several statistical indicators in order to characterize the magnetic field structure and compare the results obtained with the collisionless model to those obtained using standard collisional MHD framework. We find that important imprints of the pressure anisotropy prevails in the magnetic field and also manifest in the associated FR maps which evidence smaller correlation lengths in the collisionless MHD case. These points are remarkably noticeable for the case mimicking the conditions prevailing in ICM. Nevertheless, in this study we have neglected the decrease of pressure anisotropy due to the feedback of the instabilities that naturally arise in collisionless plasmas at small scales. This decrease may not affect the statistical imprint differences described above, but should be examined elsewhere. (AU)

• FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Special Projects
• FAPESP's process: 13/18815-0 - Magnetic reconnection and related processes in collisional and collisionless astrophysical plasmas: from solar flares to extragalactic sources
• Grantee: Grzegorz Kowal
• Support Opportunities: Scholarships in Brazil - Young Researchers
• FAPESP's process: 13/15115-8 - Study of collisionless plasma effects: application to the turbulent intracluster medium of galaxies
• Grantee: Reinaldo Santos de Lima
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/04073-2 - Magnetic reconnection and related processes in collisional and collisionless astrophysical plasmas: from solar flares to extragalactic sources
• Grantee: Grzegorz Kowal
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 10/50298-8 - Kinetic magnetohydrodynamics and astrophysical collisionless plasmas
• Grantee: Maria Soledad Nakwacki
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 09/50053-8 - Magnetic reconnection and particle acceleration in astrophysical sources and diffuse media
• Grantee: Grzegorz Kowal
• Support Opportunities: Scholarships in Brazil - Post-Doctoral