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

Understand

We present cosmological parameter constraints based on the final nine-year WMAP data, in conjunction with additional cosmological data sets.

• The WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter LCDM model.
• When WMAP data are combined with measurements of the high-l CMB anisotropy, the BAO scale, and the Hubble constant, the densities, Omegabh2, Omegach2, and Omega_L, are each determined to a precision of ~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 5sigma level, confirming the first detection of tilt based on the five-year WMAP data.