Efficient Highly Subsonic Turbulent Dynamo and Growth of Primordial Magnetic Fields

by Radhika Achikanath Chirakkara (Indian Institute of Science Education and Australian National University)

Tuesday 21 Sept 2021, 15:00 → 16:00 Europe/Stockholm

https://stockholmuniversity.zoom.us/j/940229961

We present the first study on the amplification of magnetic fields by the turbulent dynamo in the highly subsonic regime, with Mach numbers ranging from 10-3 to 0.4. We find that for the lower Mach numbers the saturation efficiency of the dynamo (Emag/Ekin)sat increases as the Mach number decreases. Even in the case when injection of energy is purely through longitudinal forcing modes, (Emag/Ekin)sat≳10-2 at a Mach number of 10-3. We apply our results to magnetic field amplification in the early Universe and predict that a turbulent dynamo can amplify primordial magnetic fields to ≳10-16 G on scales up to 0.1 pc and ≳10-13 G on scales up to 100 pc. This produces fields compatible with lower limits of the intergalactic magnetic field inferred from blazar γ -ray observations.

https://ui.adsabs.harvard.edu/abs/2021PhRvL.126i1103A/abstract