Constraints on the solid dark universe model

If the dark energy is modelled as a relativistic elastic solid then the standard CDM and \ΛCDM models, as well as lattice configurations of cosmic strings or domain walls, are points in the two-dimensional parameter space (w,c\ s²). We present a detailed analysis of the best fitting cosmological parameters in this model using data from a range of observations. We find that the \χ² is improved by \~ 10 by including the two parameters and that the $w=-1$ \ΛCDM model is only the best fit to the data when a large number of different datasets are included. Using CMB observations alone we find that w=-0.38\± 0.16 and with the addition of Large-Scale Structure data w=-0.62\± 0.15 and log c\ s=-0.77\± 0.28. We conclude that the models based on topological defects provide a good fit to the current data, although \ΛCDM cannot be ruled out.