Generation of Cosmic Magnetic Fields at Recombination
نویسنده
چکیده
It is shown that the standard cosmological model predicts ab initio generation of large-scale but very small-amplitude cosmic magnetic fields at the epoch of recombination of the primeval plasma. Matter velocities dominated by coherent flows on a scale L ≈ 50h(1 + z) Mpc lead to a dipole of radiation flux in the frame of the moving matter. Thomson scattering of the radiation differentially accelerates the electrons and ions, creating large-scale coherent electric currents and magnetic fields. This process is analyzed using magnetohydrodynamic equations which include a modification of Ohm’s law describing the effect of Thomson drag on the electrons. The field strength is estimated to be B ≃ 10G.
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