Generation of magnetic fields in Einstein-Aether gravity

Understand

Recently the lower bounds of the intergalactic magnetic fields $10^{-16} \sim 10^{-20}$ Gauss are set by gamma-ray observations while it is unlikely to generate such large scale magnetic fields through astrophysical processes.

• It is known that large scale magnetic fields could be generated if there exist cosmological vector mode perturbations in the primordial plasma.
• The vector mode, however, has only a decaying solution in General Relativity if the plasma consists of perfect fluids.
• In order to investigate a possible mechanism of magnetogenesis in the primordial plasma, here we consider cosmological perturbations in the Einstein-Aether gravity model, in which the aether field can act as a new source of vector metric perturbations and thus of magnetic fields.