Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results

• Main Authors: Hinshaw, G., Larson, D., Komatsu, Eiichiro, Spergel, D. N., Bennett, C. L., Dunkley, J., Nolta, M. R., Halpern, M., Hill, R. S., Odegard, N., Page, L., Smith, K. M., Weiland, J. L., Gold, B., Jarosik, N., Kogut, A., Limon, M., Meyer, S. S., Tucker, G. S., Wollack, E., Wright, E. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: cosmic background radiation; cosmology: observations; dark matter; early; universe; instrumentation: detectors; space vehicles; space vehicles: instruments; telescopes; baryon acoustic-oscillations; south-pole telescope; digital sky survey; supernova legacy survey; hubble-space-telescope; background power; spectrum; brightest cluster sample; massive galaxy clusters; ia; supernovae; dark energy; astronomy & astrophysics; Canada; South Pole; Lambda; Wilkinson; Hubble; South pole
• Online Access: http://hdl.handle.net/2152/42961; https://doi.org/10.15781/T2ST7F05X; https://doi.org/10.1088/0067-0049/208/2/19

We present cosmological parameter constraints based on the final nine-year Wilkinson Microwave Anisotropy Probe (WMAP) data, in conjunction with a number of additional cosmological data sets. The WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter Delta CDM model. When WMAP data are combined with measurements of the high-l cosmic microwave background anisotropy, the baryon acoustic oscillation scale, and the Hubble constant, the matter and energy densities, Omega(b)h(2), Omega(c)h(2), and Omega(Lambda), are each determined to a precision of similar to 1.5%. The amplitude of the primordial spectrum is measured to within 3%, and there is now evidence for a tilt in the primordial spectrum at the 5 sigma level, confirming the first detection of tilt based on the five-year WMAP data. At the end of the WMAP mission, the nine-year data decrease the allowable volume of the six-dimensional Delta CDM parameter space by a factor of 68,000 relative to pre-WMAP measurements. We investigate a number of data combinations and show that their Delta CDM parameter fits are consistent. New limits on deviations from the six-parameter model are presented, for example: the fractional contribution of tensor modes is limited to r < 0.13 (95% CL); the spatial curvature parameter is limited to Omega(k) = -0.0027(-0.0038)(+0.0039); the summed mass of neutrinos is limited to Sigma m(nu) < 0.44 eV (95% CL); and the number of relativistic species is found to lie within N-eff = 3.84 +/- 0.40, when the full data are analyzed. The joint constraint on N-eff and the primordial helium abundance, Y-He, agrees with the prediction of standard big bang nucleosynthesis. We compare recent Planck measurements of the Sunyaev-Zel'dovich effect with our seven-year measurements, and show their mutual agreement. Our analysis of the polarization pattern around temperature extrema is updated. This confirms a fundamental prediction of the standard cosmological model and provides a striking illustration of acoustic oscillations and adiabatic initial conditions in the early universe. Canadian Institute for Advanced Research Johns Hopkins University Perimeter Institute by the Government of Canada through Industry Canada Province of Ontario through the Ministry of Research Innovation NASA NNX08AL43G, NNX11AD25G NSF AST-0807649, PHY-0758153 Canada Foundation for Innovation under Compute Canada Government of Ontario Ontario Research Fund-Research Excellence University of Toronto NASA Headquarters Astronomy