DASI Three-Year Cosmic Microwave Background Polarization Results
Erik M. Leitch, J. M. Kovac, N. W. Halverson, J. E. Carlstrom, C. Pryke, M. W. E. Smith
TL;DR
The study analyzes the complete 3-year DASI polarization data to test ΛCDM predictions for the CMB's polarization. It employs a calibrated interferometric approach and a likelihood framework to extract E- and B-mode spectra and TE cross-correlation, confirming a robust E-mode signal at $6.3\sigma$ and TE at $2.9\sigma$ while constraining B-modes to be consistent with zero with a stringent upper limit. The results align with the concordance polarization spectrum and show negligible foreground contamination, underscoring the reliability of ground-based polarization measurements. Overall, the work reinforces the standard cosmological model's polarization predictions and informs future CMB polarization experiments.
Abstract
We present the analysis of the complete 3-year data set obtained with the Degree Angular Scale Interferometer (DASI) polarization experiment, operating from the Amundsen-Scott South Pole research station. Additional data obtained at the end of the 2002 Austral winter and throughout the 2003 season were added to the data from which the first detection of polarization of the cosmic microwave background radiation was reported. The analysis of the combined data supports, with increased statistical power, all of the conclusions drawn from the initial data set. In particular, the detection of E-mode polarization is increased to 6.3 sigma confidence level, TE cross-polarization is detected at 2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit well below the level of the detected E-mode polarization. The results are in excellent agreement with the predictions of the cosmological model that has emerged from CMB temperature measurements. The analysis also demonstrates that contamination of the data by known sources of foreground emission is insignificant.