FIRST-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP)1 OBSERVATIONS: DETERMINATION OF COSMOLOGICAL PARAMETERS

WMAP precision data enable accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat -dominated universe seeded by a nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP data. For the WMAP data only, the best-fit parameters are h 0:72 0:05, bh2 0:024 0:001, mh2 0:14 0:02, 0:166þ0:0760:071, ns 0:99 0:04, and 8 0:9 0:1. With parameters fixed only byWMAP data, we can fit finer scale cosmic microwave background (CMB) measure-ments and measurements of large-scale structure (galaxy surveys and the Ly forest). This simple model is also consistent with a host of other astronomical measurements: its inferred age of the universe is consistent with stellar ages, the baryon/photon ratio is consistent with measurements of the [D/H] ratio, and the inferred Hubble constant is consistent with local observations of the expansion rate. We then fit the model parameters to a combination of WMAP data with other finer scale CMB experiments (ACBAR and CBI), 2dFGRS measurements, and Ly forest data to find the model’s best-fit cosmological parameters: h 0:71þ0:040:03, bh2 0:0224 0:0009, mh2 0:135þ0:0080:009, 0:17 0:06, ns(0.05 Mpc1) = 0:93 0:03, and 8 0:84 0:04.WMAP’s best determination of 0:17 0:04 arises directly from the temperature-polarization (TE) data and not from this model fit, but they are consistent. These parameters imply that th