Cosmological Structure Formation Creates Large‐Scale Magnetic Fields

This paper examines the generation of seed magnetic fields due to the growthof cosmological perturbations. In the radiation era, different rates ofscattering from photons induce local differences in the ion and electrondensity and velocity fields. The currents due to the relative motion of thesefluids generate magnetic fields on all cosmological scales, peaking at amagnitude of ~ 10^{-24} Gauss at the epoch of recombination. Magnetic fieldsgenerated in this manner provide a promising candidate for the seeds ofmagnetic fields presently observed on galactic and extra-galactic scales.Comment: 9 pages, 3 figures, important error corrected: with the correction, overall field strengths are 10^{-24} Gauss, discussion of other works in the literature expanded, and references adde