Measurement of cosmic microwave background polarization power spectra from two years of BICEP data

• Published in: The Astrophysical Journal
• Main Authors: Chiang, H. C., Ade, Peter A. R., Barkats, D., Battle, J. O., Bierman, E. M., Bock, J. J., Dowell, C. D., Duband, L., Hivon, E. F., Holzapfel, W. L., Hristov, V. V., Jones, W. C., Keating, B. G., Kovac, J. M., Kuo, C. L., Lange, A. E., Leitch, E. M., Mason, P. V., Matsumura, T., Nguyen, H. T., Ponthieu, N., Pryke, C., Richter, S., Rocha, G., Sheehy, C., Takahashi, Y. D., Tolan, J. E., Yoon, K. W.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: IOPScience 2010
• Subjects: QB Astronomy; South Pole; South pole
• Online Access: https://orca.cardiff.ac.uk/id/eprint/33740/; https://doi.org/10.1088/0004-637X/711/2/1123

Background Imaging of Cosmic Extragalactic Polarization (BICEP) is a bolometric polarimeter designed to measure the inflationary B-mode polarization of the cosmic microwave background (CMB) at degree angular scales. During three seasons of observing at the South Pole (2006 through 2008), BICEP mapped ~2% of the sky chosen to be uniquely clean of polarized foreground emission. Here, we present initial results derived from a subset of the data acquired during the first two years. We present maps of temperature, Stokes Q and U, E and B modes, and associated angular power spectra. We demonstrate that the polarization data are self-consistent by performing a series of jackknife tests. We study potential systematic errors in detail and show that they are sub-dominant to the statistical errors. We measure the E-mode angular power spectrum with high precision at 21 ≤ ℓ ≤ 335, detecting for the first time the peak expected at ℓ ~ 140. The measured E-mode spectrum is consistent with expectations from a ΛCDM model, and the B-mode spectrum is consistent with zero. The tensor-to-scalar ratio derived from the B-mode spectrum is r = 0.02(+0.31) (–0.26), or r < 0.72 at 95% confidence, the first meaningful constraint on the inflationary gravitational wave background to come directly from CMB B-mode polarization.