Primordial magnetic fields and nonlinear electrodynamics

Understand

The creation of large scale magnetic fields is studied in an inflationary universe where electrodynamics is assumed to be nonlinear.

• After inflation ends electrodynamics becomes linear and thus the description of reheating and the subsequent radiation dominated stage are unaltered.
• The nonlinear regime of electrodynamics is described by lagrangians having a power law dependence on one of the invariants of the electromagnetic field.
• It is found that there is a range of parameters for which primordial magnetic fields of cosmologically interesting strengths can be created.