Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium
The amplification of magnetic fields (MFs) in the intracluster medium (ICM) is attributed to turbulent dynamo (TD) action, which is generally derived in the collisional-MHD framework. However, this assumption is poorly justified a priori, since in the ICM the ion mean free path between collisions is...
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2014
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_0004637X_v781_n2_p_SantosLima https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_0004637X_v781_n2_p_SantosLima_oai |
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I28-R145-paper_0004637X_v781_n2_p_SantosLima_oai2024-08-16 Santos-Lima, R. De Gouveia Dal Pino, E.M. Kowal, G. Falceta-Gonçalves, D. Lazarian, A. Nakwacki, M.S. 2014 The amplification of magnetic fields (MFs) in the intracluster medium (ICM) is attributed to turbulent dynamo (TD) action, which is generally derived in the collisional-MHD framework. However, this assumption is poorly justified a priori, since in the ICM the ion mean free path between collisions is of the order of the dynamical scales, thus requiring a collisionless MHD description. The present study uses an anisotropic plasma pressure that brings the plasma within a parametric space where collisionless instabilities take place. In this model, a relaxation term of the pressure anisotropy simulates the feedback of the mirror and firehose instabilities, in consistency with empirical studies. Our three-dimensional numerical simulations of forced transonic turbulence, aiming the modeling of the turbulent ICM, were performed for different initial values of the MF intensity and different relaxation rates of the pressure anisotropy. We found that in the high-β plasma regime corresponding to the ICM conditions, a fast anisotropy relaxation rate gives results that are similar to the collisional-MHD model, as far as the statistical properties of the turbulence are concerned. Also, the TD amplification of seed MFs was found to be similar to the collisional-MHD model. The simulations that do not employ the anisotropy relaxation deviate significantly from the collisional-MHD results and show more power at the small-scale fluctuations of both density and velocity as a result of the action of the instabilities. For these simulations, the large-scale fluctuations in the MF are mostly suppressed and the TD fails in amplifying seed MFs. © 2014. The American Astronomical Society. All rights reserved. Fil:Nakwacki, M.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. application/pdf http://hdl.handle.net/20.500.12110/paper_0004637X_v781_n2_p_SantosLima info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar Astrophys. J. 2014;781(2) galaxies: clusters: intracluster medium magnetic fields magnetohydrodynamics (MHD) turbulence Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_0004637X_v781_n2_p_SantosLima_oai |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-145 |
| collection |
Repositorio Digital de la Universidad de Buenos Aires (UBA) |
| topic |
galaxies: clusters: intracluster medium magnetic fields magnetohydrodynamics (MHD) turbulence |
| spellingShingle |
galaxies: clusters: intracluster medium magnetic fields magnetohydrodynamics (MHD) turbulence Santos-Lima, R. De Gouveia Dal Pino, E.M. Kowal, G. Falceta-Gonçalves, D. Lazarian, A. Nakwacki, M.S. Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium |
| topic_facet |
galaxies: clusters: intracluster medium magnetic fields magnetohydrodynamics (MHD) turbulence |
| description |
The amplification of magnetic fields (MFs) in the intracluster medium (ICM) is attributed to turbulent dynamo (TD) action, which is generally derived in the collisional-MHD framework. However, this assumption is poorly justified a priori, since in the ICM the ion mean free path between collisions is of the order of the dynamical scales, thus requiring a collisionless MHD description. The present study uses an anisotropic plasma pressure that brings the plasma within a parametric space where collisionless instabilities take place. In this model, a relaxation term of the pressure anisotropy simulates the feedback of the mirror and firehose instabilities, in consistency with empirical studies. Our three-dimensional numerical simulations of forced transonic turbulence, aiming the modeling of the turbulent ICM, were performed for different initial values of the MF intensity and different relaxation rates of the pressure anisotropy. We found that in the high-β plasma regime corresponding to the ICM conditions, a fast anisotropy relaxation rate gives results that are similar to the collisional-MHD model, as far as the statistical properties of the turbulence are concerned. Also, the TD amplification of seed MFs was found to be similar to the collisional-MHD model. The simulations that do not employ the anisotropy relaxation deviate significantly from the collisional-MHD results and show more power at the small-scale fluctuations of both density and velocity as a result of the action of the instabilities. For these simulations, the large-scale fluctuations in the MF are mostly suppressed and the TD fails in amplifying seed MFs. © 2014. The American Astronomical Society. All rights reserved. |
| format |
Artículo Artículo publishedVersion |
| author |
Santos-Lima, R. De Gouveia Dal Pino, E.M. Kowal, G. Falceta-Gonçalves, D. Lazarian, A. Nakwacki, M.S. |
| author_facet |
Santos-Lima, R. De Gouveia Dal Pino, E.M. Kowal, G. Falceta-Gonçalves, D. Lazarian, A. Nakwacki, M.S. |
| author_sort |
Santos-Lima, R. |
| title |
Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium |
| title_short |
Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium |
| title_full |
Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium |
| title_fullStr |
Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium |
| title_full_unstemmed |
Magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: An application to the intracluster medium |
| title_sort |
magnetic field amplification and evolution in turbulent collisionless magnetohydrodynamics: an application to the intracluster medium |
| publishDate |
2014 |
| url |
http://hdl.handle.net/20.500.12110/paper_0004637X_v781_n2_p_SantosLima https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_0004637X_v781_n2_p_SantosLima_oai |
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1809357188320198656 |