Speaker
Description
In the context of the standard cosmological perturbation theory, non-linear couplings of first-order scalar perturbations create second-order vector perturbations, which generate magnetic fields through the Harrison mechanism.
We find that the magnetic fields from the purely second-order vector perturbations partially cancel out the magnetic fields from one of the product-terms of the first-order scalar modes. Therefore, the amplitude of the magnetic fields on small scales, $k\geq 10 h{\rm Mpc}^{−1}$, is smaller than the previous estimates. The amplitude of the generated magnetic fields at cosmological recombination is about $B_{\rm rec}=5.0\times 10^{−24} {\rm Gauss}$ on $k=5.0\times 10^{−1} h{\rm Mpc}^{−1}$. Finally, we discuss the reason of the discrepancies that exist in estimates of the amplitude of magnetic fields among other authors.
