FiveYear Wilkinson Microwave Anisotropy Probe Observations: Data Processing, Sky Maps, and Basic Results
Abstract
We present new fullsky temperature and polarization maps in five frequency bands from 23 to 94 GHz, based on data from the first five years of the Wilkinson Microwave Anisotropy Probe (WMAP) sky survey. The new maps are consistent with previous maps and are more sensitive. The fiveyear maps incorporate several improvements in data processing made possible by the additional years of data and by a more complete analysis of the instrument calibration and inflight beam response. We present several new tests for systematic errors in the polarization data and conclude that Wband polarization data is not yet suitable for cosmological studies, but we suggest directions for further study. We do find that Kaband data is suitable for use; in conjunction with the additional years of data, the addition of Ka band to the previously used Q and Vband channels significantly reduces the uncertainty in the optical depth parameter, τ. Further scientific results from the fiveyear data analysis are presented in six companion papers and are summarized in Section 7 of this paper. With the fiveyear WMAP data, we detect no convincing deviations from the minimal sixparameter ΛCDM model: a flat universe dominated by a cosmological constant, with adiabatic and nearly scaleinvariant Gaussian fluctuations. Using WMAP data combined with measurements of Type Ia supernovae and Baryon Acoustic Oscillations in the galaxy distribution, we find (68% CL uncertainties): Ω_{ b } h ^{2} = 0.02267^{+0.00058} _{0.00059}, Ω_{ c } h ^{2} = 0.1131 ± 0.0034, Ω_{Λ} = 0.726 ± 0.015, n_{s} = 0.960 ± 0.013, τ = 0.084 ± 0.016, and Δ_{R}^2 = (2.445± 0.096)× 10^{9} at k = 0.002 Mpc^{1}. From these we derive σ_{8} = 0.812 ± 0.026, H _{0} = 70.5 ± 1.3 km s^{1} Mpc^{1}, Ω_{ b } = 0.0456 ± 0.0015, Ω_{ c } = 0.228 ± 0.013, Ω_{ m } h ^{2} = 0.1358^{+0.0037} _{0.0036}, z _{reion} = 10.9 ± 1.4, and t _{0} = 13.72 ± 0.12 Gyr. The new limit on the tensortoscalar ratio is r < 0.22(95%CL), while the evidence for a running spectral index is insignificant, dn_{s} /dln k = 0.028 ± 0.020 (68% CL). We obtain tight, simultaneous limits on the (constant) dark energy equation of state and the spatial curvature of the universe: 0.14 < 1 + w < 0.12(95%CL) and 0.0179 < Ω_{ k } < 0.0081(95%CL). The number of relativistic degrees of freedom, expressed in units of the effective number of neutrino species, is found to be N _{eff} = 4.4 ± 1.5 (68% CL), consistent with the standard value of 3.04. Models with N _{eff} = 0 are disfavored at >99.5% confidence. Finally, new limits on physically motivated primordial nonGaussianity parameters are 9 < f ^{local} _{NL} < 111 (95% CL) and 151 < f ^{equil} _{NL} < 253 (95% CL) for the local and equilateral models, respectively.
WMAP is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.
 Publication:

The Astrophysical Journal Supplement Series
 Pub Date:
 February 2009
 DOI:
 10.1088/00670049/180/2/225
 arXiv:
 arXiv:0803.0732
 Bibcode:
 2009ApJS..180..225H
 Keywords:

 cosmic microwave background;
 cosmology: observations;
 early universe;
 dark matter;
 space vehicles;
 space vehicles: instruments;
 instrumentation: detectors;
 telescopes;
 Astrophysics
 EPrint:
 46 pages, 13 figures, and 7 tables. Version accepted for publication, ApJS, Feb2009. Includes 5year dipole results and additional references. Also available at http://lambda.gsfc.nasa.gov/product/map/dr3/map_bibliography.cfm