Large-scale magnetic fields from density perturbations

S. MATARRESE, S. MOLLERACH, A. NOTARI Y A. RIOTTO

PHYSICAL REVIEW D - PARTICLE AND FILDS

The American Physical Society

Año: 2005 vol. 71 p. 1 - 7

0556-2821

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 B[approximate]10-23(lambda/Mpc)-2 G, on comoving scales lambda>~1 Mpc.