Magnetogenesis from Cosmological Velocity Perturbations

Cosmology the branch of astronomy which studies the formation and evolution of the structure of the entire universe on the largest scales. Recent observations seem to indicate the presence of magnetic fields on all scales of the universe. It is possible that magnetic fields have existed since very early times while the mechanisms exist to generate these fields in the late universe. Here in our research we studied the velocity perturbation scenario as a dynamo amplification of the primordial seeds field. We describe the early universe stage as multifluid, consisting of charge-neutral two-component matter and radiation fluids, linearised around the Friedmann-Lemaître-Robertson-Walker models. The oscillatory behaviour of the electromagnetic field with a new weakly damped mode is identified in addition to the standard gravitational instability picture. Vertical velocity perturbations are further found to generate magnetic fields of sufficient strength to provide a seed for the galactic dynamo. Subsequent amplification in such a way could easily lead to the observed magnetic fields in galaxies.