Hall-MHD small-scale dynamos - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate

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Abstract: Much of the progress in our understanding of dynamo mechanisms has been madewithin the theoretical framework of magnetohydrodynamics MHD. However, forsufficiently diffuse media, the Hall effect eventually becomes non-negligible.We present results from three dimensional simulations of the Hall-MHD equationssubjected to random non-helical forcing. We study the role of the Hall effectin the dynamo efficiency for different values of the Hall parameter, using apseudospectral code to achieve exponentially fast convergence. We also studyenergy transfer rates among spatial scales to determine the relative importanceof the various nonlinear effects in the dynamo process and in the energycascade. The Hall effect produces a reduction of the direct energy cascade atscales larger than the Hall scale, and therefore leads to smaller energydissipation rates. Finally, we present results stemming from simulations atlarge magnetic Prandtl numbers, which is the relevant regime in hot and diffusemedia such a the interstellar medium.

Author: Daniel O. Gomez, Pablo D. Mininni, Pablo Dmitruk

Source: https://arxiv.org/

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