  Exact solutions of the perturbations equations in the magnetized LambdaCDM
scenario are presented. They apply during the dark ages and, more specifically,
after the baryons are freed from the drag of the photons. The magnetized growth
rate of matter perturbations is compared with the growth index obtained in the
concordance paradigm and under the assumption that dark energy does not cluster
for a redshift window ranging from the epoch of reionization to the stage of
dark-energy dominance. The constraints derived from this analysis are shown to
be qualitatively complementary and quantitatively competitive with the bounds
stemming from the analysis of the distortion patterns induced by the magnetized
adiabatic mode on the temperature and polarization anisotropies of the Cosmic
Microwave Background.
