First‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Temperature‐Polarization Correlation

The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in Stokes I, Q, and U parameters at frequencies 23, 33, 41, 61, and 94 GHz. We detect correlations between the temperature and polarization maps significant at more than 10 standard deviations. The correlations are present in all WMAP frequency bands with similar amplitude from 23 to 94 GHz, and are consistent with a superposition of a CMB signal with a weak foreground. The fitted CMB component is robust against different data combinations and fitting techniques. On small angular scales theta 20 agree well with the signal predicted solely from the temperature power spectra, with no additional free parameters. We detect excess power on…