Effects of non-linearities on magnetic field generation

Understand

Magnetic fields are present on all scales in the Universe.

• While we understand the processes which amplify the fields fairly well, we do not have a "natural" mechanism to generate the small initial seed fields.
• By using fully relativistic cosmological perturbation theory and going beyond the usual confines of linear theory we show analytically how magnetic fields are generated.
• This is the first analytical calculation of the magnetic field at second order, using gauge-invariant cosmological perturbation theory, and including all the source terms.