First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: The Angular Power Spectrum.

摘要

We present the angular power spectrum derived from the first-year Wlkinson Microwave Anisotropy Probe (WMAP) sky maps. We study a variety of power spectrum estimation methods and data combina- tions and demonstrate that the results are robust. The data are modestly contaminated by diffuse Galactic foreground emission, but we show that a simple Galactic template model is sufficient to remove the signal. Point sources produce a modest contamination in the low frequency data. After masking approx. 700 known bright sources from the maps, we estimate residual sources contribute approx. 3500 microK to the 2nd power at 41 GHz, and approx. 130 microK to the second power at 94 GHz, to the power spectrum (l(l+ 1)C1/2 pi) at l = 1000. Systematic errors are negligible compared to the (modest) level of foreground emission. Our best estimate of the power spectrum is derived from 28 cross-power spectra of statistically independent channels. The final spectrum is essentially independent of the noise properties of an individual radiometer. The resulting spectrum provides a definitive measurement of the CMB power spectrum, with uncertainties limited by cosmic variance, up to 1 approx. 350.