We propose that cosmological magnetic fields generated in regions of finite spatial dimensions may manifest themselves in the global dynamics of the Universe as ‘ dark energy ’ .
We test our model in the context of spatially flat cosmological models by assuming that the Universe contains non-relativistic matter \rho _ { m } \propto \alpha ^ { -3 } , dark energy \rho _ { Q } \propto \alpha ^ { -3 ( 1 + w ) } , and an extra fluid with \rho _ { B } \propto \alpha ^ { n - 3 } that corresponds to the magnetic field .
We place constraints on the main cosmological parameters of our model by combining the recent supernovae type Ia data and the differential ages of passively evolving galaxies .
In particular , we find that the model which best reproduces the observational data when \Omega _ { m } = 0.26 is one with \Omega _ { B } \simeq 0.03 , n \simeq 7.68 , \Omega _ { Q } \simeq 0.71 and w \simeq - 0.8 .