Origin of primeval seed magnetism in rotating astrophysical bodies

Abstract

We show that a primeval seed magnetic field arises due to spin-degeneracy breaking of fermions caused by the dragging of inertial frames in the curved spacetime of rotating astrophysical bodies. This seed magnetic field would arise even due to electrically neutral fermions such as neutrons. As examples, firstly we show that an ideal neutron star rotating at 500 revolutions per second, having mass 0.83 M⊙ and described by an ensemble of degenerate neutrons, would have 0.12 Gauss seed magnetic field at its center arising through the breaking of spin-degeneracy. Secondly, similar seed field at a proto-galactic stage for the Milky Way galaxy as implied by its observed rotation curve is estimated to be between 10-19–10-24 Gauss, a field strength which is known to be sufficient to produce presently observed microgauss magnetic field.