The cosmological model consisting of a nonlinear magnetic field obeying the Lagrangian \mathcal { L } = \gamma F ^ { \alpha } , F being the electromagnetic invariant , coupled to a Robertson-Walker geometry is tested with observational data of Type Ia Supernovae , Long Gamma-Ray Bursts and Hubble parameter measurements .
The statistical analysis show that the inclusion of nonlinear electromagnetic matter is enough to produce the observed accelerated expansion , with not need of including a dark energy component .
The electromagnetic matter with abundance \Omega _ { B } , gives as best fit from the combination of all observational data sets \Omega _ { B } = 0.562 ^ { +0.037 } _ { -0.038 } for the scenario in which \alpha = -1 , \Omega _ { B } = 0.654 ^ { +0.040 } _ { -0.040 } for the scenario with \alpha = -1 / 4 and \Omega _ { B } = 0.683 ^ { +0.039 } _ { -0.043 } for the one with \alpha = -1 / 8 .
These results indicate that nonlinear electromagnetic matter could play the role of dark energy , with the theoretical advantage of being a mensurable field .