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, P. 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.
• Other Authors: Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: cosmic background radiation; cosmology: observations; gravitational waves; inflation; polarization; Astrophysics - Cosmology and Extragalactic Astrophysics; [SDU]Sciences of the Universe [physics]; South Pole; South pole
• Online Access: https://hal.science/hal-03646176; https://doi.org/10.1088/0004-637X/711/2/1123

International audience 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 <= ell <= 335, detecting for the first time the peak expected at ell ~ 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.