Large-scale galaxy correlations as a test for dark energy

We have shown earlier that, contrary to popular belief, Einstein-de Sitter (E-deS) models can still fit the WMAP data on the cosmic microwave background provided one adopts a low Hubble constant and relaxes the usual assumption that the primordial density perturbation is scale-free. The recent SDSS measurement of the large-scale correlation function of luminous red galaxies at z similar to 0.35 has however provided a new constraint by detecting a "baryon acoustic peak". Our best-fit E-deS models do possess a baryonic feature at a similar physical scale as the best-fit.CDM concordance model, but do not fit the new observations as well as the latter. In particular the shape of the correlation function in the range similar to 10- 100 h(-1) Mpc cannot be reproduced properly without violating the CMB angular power spectrum in the multipole range l similar to 100-1000. Thus, the combination of the CMB fluctuations and the shape of the correlation function up to similar to 100 h(-1) Mpc, if confirmed, does seem to require dark energy for a homogeneous cosmological model based on ( adiabatic) inflationary perturbations.