Abstract
We derive the minimal seed magnetic field which unavoidably arises in the radiation and matter eras, prior to recombination, by the rotational velocity of ions and electrons, gravitationally induced by the nonlinear evolution of primordial density perturbations. The resulting magnetic field power spectrum is fully determined by the amplitude and spectral index of density perturbations. The rms amplitude of the seed field at recombination is , on comoving scales .
- Received 2 November 2004
DOI:https://doi.org/10.1103/PhysRevD.71.043502
©2005 American Physical Society