We use recent results from the Wilkinson Microwave Anisotropy Probe ( WMAP ) for the locations of peaks and troughs of the Cosmic Microwave Background ( CMB ) power spectrum , together with constraints from large-scale structure , to study a quintessence model in which the pure exponential potential is modified by a polynomial factor .
We find that the model is compatible with all the recent data for a wide range of cosmological and potential parameters .
Moreover , quintessence is favoured compared to \Lambda CDM for n _ { s } \approx 1 and relatively high values of the average fraction of dark energy before last scattering ( “ early quintessence ” ) ; for n _ { s } < 1 , quintessence and \Lambda CDM give similar results , except for high values of early quintessence , in which case \Lambda CDM is favoured .