We cross-correlate the third-year WMAP data with galaxy samples extracted from the SDSS DR4 ( SDSS4 ) covering 13 % of the sky , increasing by a factor of 3.7 the volume sampled in previous analysis .
The new measurements confirm a positive cross-correlation with higher significance ( total signal-to-noise of about 4.7 ) .
The correlation as a function of angular scale is well fitted by the integrated Sachs-Wolfe ( ISW ) effect for LCDM flat FRW models with a cosmological constant .
The combined analysis of different samples gives \Omega _ { \Lambda } = 0.80 - 0.85 ( 68 % Confidence Level , CL ) or 0.77 - 0.86 ( 95 % CL ) .
We find similar best fit values for \Omega _ { \Lambda } for different galaxy samples with median redshifts of z \simeq 0.3 and z \simeq 0.5 , indicating that the data scale with redshift as predicted by the LCDM cosmology ( with equation of state parameter w = -1 ) .
This agreement is not trivial , but can not yet be used to break the degeneracy constraints in the w versus \Omega _ { \Lambda } plane using only the ISW data .