Origin of electric and magnetic fields in the early universe

Abstract

A fundamental unanswered question of cosmology is the origin of the magnetic fields observed in the various types of astrophysical bodies. It is still argued whether these magnetic fields are primordial or whether they have been amplified from an initial small seed field. We shall show that a large scale magnetic field is generated by motions of an electric field in the plasma that constituted the early universe at the time of decoupling of matter from radiation. This primordial electric field is a consequence of temperature and pressure gradients that produce charge separation in the plasma of electrons and protons. We calculate of the magnitude of these primordial fields using expected galactic size and streaming velocities as well as values of temperature and pressure gradients that are observed near the time of decoupling. We calculate the large scale primordial magnetic of dynamo amplification of this seed field that has occurred during the formation of the various astrophysical bodies.