COSMOLOGICAL SEED MAGNETIC-FIELD FROM INFLATION

We extend the canonical exponential potential scalar field inflation modified hot big bang model by adding an inflation epoch coupling, between the scalar field PHI responsible for inflation and an Abelian gauge field A(mu), proportional-to e(alpha-PHI) F(mu-nu)F(mu-nu) (where F(mu-nu) = partial derivative (mu) A(nu) - partial derivative (nu) A(mu) and alpha is a parameter). Requiring that the homogeneous part of the scalar field "freeze" at a constant value at the inflation-radiation (reheating) transition, we find that it is possible to generate a present intergalactic magnetic field of strength (depending upon the values of parameters of the model) between lesser-than-or-similar-to 10(-65) and greater-than-or-similar-to 10(-10) G, on a scale of 1/1000 the present Hubble radius. The larger values provide an example of a primeval seed magnetic field that might be amplified by anisotropic protogalactic collapse and galactic differential rotation to produce the observed galactic magnetic fields.