Improved Measurements of the CMB Power Spectrum with ACBAR
Abstract
We report improved measurements of temperature anisotropies in the cosmic microwave background (CMB) radiation made with the Arcminute Cosmology Bolometer Array Receiver (ACBAR). In this paper, we use a new analysis technique and include 30% more data from the 2001 and 2002 observing seasons than the first release to derive a new set of bandpower measurements with significantly smaller uncertainties. The planetbased calibration used previously has been replaced by comparing the flux of RCW 38 as measured by ACBAR and BOOMERANG to transfer the WMAPbased BOOMERANG calibration to ACBAR. The resulting power spectrum is consistent with the theoretical predictions for a spatially flat, dark energydominated ΛCDM cosmology, including the effects of gravitational lensing. Despite the exponential damping on small angular scales, the primary CMB fluctuations are detected with a signaltonoise ratio of greater than 4, up to multipoles of l=2000. This increase in the precision of the finescale CMB power spectrum leads to only a modest decrease in the uncertainties on the parameters of the standard cosmological model. At high angular resolution, secondary anisotropies are predicted to be a significant contribution to the measured anisotropy. A joint analysis of the ACBAR results at 150 GHz and the CBI results at 30 GHz in the multipole range 2000<l<3000 shows that the power, reported by CBI in excess of the predicted primary anisotropy, has a frequency spectrum consistent with the thermal SunyaevZel'dovich effect and inconsistent with primary CMB. The results reported here are derived from a subset of the total ACBAR data set; the final ACBAR power spectrum at 150 GHz will include 3.7 times more effective integration time and 6.5 times more sky coverage than is used here.
 Publication:

The Astrophysical Journal
 Pub Date:
 August 2007
 DOI:
 10.1086/518401
 arXiv:
 arXiv:astroph/0611198
 Bibcode:
 2007ApJ...664..687K
 Keywords:

 Cosmology: Cosmic Microwave Background;
 Cosmology: Observations;
 Astrophysics
 EPrint:
 19 pages, 9 figures, ApJ