Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology

摘要

A simple cosmological model with only six parameters (matter density, Omega_mh^2, baryon density, Omega_b h^2, Hubble Constant, H_0, amplitude offluctuations, sigma_8, optical depth, tau, and a slope for the scalarperturbation spectrum, n_s) fits not only the three year WMAP temperature andpolarization data, but also small scale CMB data, light element abundances,large-scale structure observations, and the supernova luminosity/distancerelationship. Using WMAP data only, the best fit values for cosmologicalparameters for the power-law flat LCDM model are (Omega_m h^2, Omega_b h^2, h,n_s, tau, sigma_8) = 0.1277+0.0080-0.0079, 0.02229+-0.00073, 0.732+0.031-0.032,0.958+-0.016, 0.089+-0.030, 0.761+0.049-0.048). The three year datadramatically shrink the allowed volume in this six dimensional parameter space.Assuming that the primordial fluctuations are adiabatic with a power lawspectrum, the WMAP data_alone_ require dark matter, and favor a spectral indexthat is significantly less than the Harrison-Zel'dovich-Peebles scale-invariantspectrum (n_s=1, r=0). Models that suppress large-scale power through a runningspectral index or a large-scale cut-off in the power spectrum are a better fitto the WMAP and small scale CMB data than the power-law LCDM model; however,the improvement in the fit to the WMAP data is only Delta chi^2 = 3 for 1 extradegree of freedom. The combination of WMAP and other astronomical data yieldssignificant constraints on the geometry of the universe, the equation of stateof the dark energy, the gravitational wave energy density, and neutrinoproperties. Consistent with the predictions of simple inflationary theories, wedetect no significant deviations from Gaussianity in the CMB maps.