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Abstract: We present kinematic simulations of a galactic dynamo model based on thelarge scale differential rotation and the small scale helical fluctuations dueto supernova explosions. We report for the first time direct numericalsimulations of the full galactic dynamo using an unparameterized globalapproach. We argue that the scale of helicity injection is large enough to bedirectly resolved rather than parameterized. While the actual superbubblecharacteristics can only be approached, we show that numerical simulationsyield magnetic structures which are close both to the observations and to theprevious parameterized mean field models. In particular, the quadrupolarsymmetry and the spiraling properties of the field are reproduced. Moreover,our simulations show that the presence of a vertical inflow plays an essentialrole to increase the magnetic growth rate. This observation could indicate animportant role of the downward flow possibly linked with galactic fountainsin sustaining galactic magnetic fields.



Autor: Christophe Gissinger, Sebastien Fromang, Emmanuel Dormy

Fuente: https://arxiv.org/







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