Constraints on quintessence using recent cosmological data

Recent data, including the three-year WMAP data, the full 2dF galaxy power spectrum and the first-year data of the Supernova Legacy Survey, are used to constrain model parameters in quintessence cosmologies. In particular, we discuss the inverse power-law (RP) and SUGRA potentials and compare parameter constraints with those for Lambda CDM. Both potentials fit current observations with a goodness of fit comparable or better than Lambda CDM. The constraints on the energy scale.DE appearing in both potential expressions are however different. For RP, only energy scales around the cosmological constant limit are allowed, making the allowed models quite similar to Lambda CDM. For SUGRA Lambda(DE) values approximately up to the electroweak energy scale are still allowed, while other parameter intervals are slightly but significantly displaced. In particular, a value of the primeval spectral index n(s) = 1 is still allowed at the 95% c. l., and this can have an impact on constraints on possible inflationary potentials.