The sporadic nature of the small-scale dynamo in simulations of the interstellar medium and its effects on the large scale dynamo and galactic magnetic fields
by
Frederick Gent
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Europe/Stockholm
Albano 3: 6228 - Mega (22 seats) (Albano Building 3)
We probe the properties of the galactic dynamo on the kpc scale within supernova-driven turbulence of the interstellar medium (ISM). A suite of simulations in periodic, unstratified demonstrate numerical convergence for the properties of the small-scale dynamo (SSD) for grid resolution of 1 parsec along each edge or better. Saturation of the SSD occurs within 10 to 30 Myrs at energy density around 5% of the equipartion with the kinetic energy. The growth rates can be highly sporadic and depend on the filling fraction of the hot gas, in which the dynamo is most efficient. SSD is very easy to excite under conditions typical of the ISM. Applying the supernova-driven turbulence to stratified galactic disks, with parameters similar to those in the solar neighbourhood of the Milky Way. We investigate the interaction between the SSD and the LSD evolving up to 5 Gyr. We also observe an unexpected interaction between the LSD and the anisotropic kinematic alpha-effect (AKA) with respect to rate of galactocentric shear.
