Magnetic field amplification by the small-scale dynamo in the early Universe

Understand

In this paper we show that the Universe is already strongly magnetized at very early epochs during cosmic evolution.

• Our calculations are based on the efficient amplification of weak magnetic seed fields, which are unavoidably present in the early Universe, by the turbulent small-scale dynamo.
• We identify two mechanisms for the generation of turbulence in the radiation dominated epoch where velocity fluctuations are produced by the primordial density perturbation and by possible first-order phase transitions at the electroweak or QCD scales.
• We show that all the necessities for the small-scale dynamo to work are fulfilled.