Speaker
Dr
Oliver Gressel
Description
Supernovae are known to be the dominant energy source for
driving turbulence in the interstellar medium. Yet, their
effect on magnetic field amplification in spiral galaxies is
still poorly understood. Analytical models based on the
uncorrelated-ensemble approach predicted that any created
field will be expelled from the disk before a significant
amplification can occur. By means of direct simulations of
supernova-driven turbulence, we demonstrate that this is not
the case. Accounting for vertical stratification and
galactic differential rotation, we find an exponential
amplification of the mean field on timescales of 100 Myr. We
highlight the importance of rotation in the generation of
helicity by showing that a similar mechanism based on
Cartesian shear does not lead to a sustained amplification
of the mean magnetic field.
