We report cosmic microwave background (CMB) power-spectrum measurements from the first 100 deg2 field observed by the South Pole Telescope (SPT) at 150 and 220 GHz. On angular scales where the primary CMB anisotropy is dominant, l ≲ 3000, the SPT power spectrum is consistent with the standard ACDM cosmology. On smaller scales, we see strong evidence for a point-source contribution, consistent with a population of dusty, star-forming galaxies. After we mask bright point sources, anisotropy power on angular scales of 3000 <l < 9500 is detected with a signal-to-noise ratio ≳50 at both frequencies. We combine the 150 and 220 GHz data to remove the majority of the point-source power and use the point-source-subtracted spectrum to detect Sunyaev-Zel'dovich (SZ) power at 2.6a. At l = 3000, the SZpower in the subtractedbandpowers is 4.2 ± 1.5/μK2, which is significantly lower than the power predicted by a fiducial model using WMAP5 cosmological parameters. This discrepancy may suggest that contemporary galaxy cluster models overestimate the thermal pressure of intracluster gas. Alternatively, this result can be interpreted as evidence for lower values of σ8. When combined with an estimate of the kinetic SZ contribution, the measured SZ amplitude shifts σ8 from the primary CMB anisotropy derived constraint of 0.794 ± 0.028 down to 0.773 ± 0.025. The uncertainty in the constraint on σ8 from this analysis is dominated by uncertainties in the theoretical modeling required to predict the amplitude of the SZ power spectrum for a given set of cosmological parameters.
- Cosmic background radiation
- Cosmological parameters
- Cosmology: observations
- Galaxies: clusters: intracluster medium
- Large-scale structure of universe