Detection of B-Mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope
Ade, P. A. R.; Bock, J. J.; Chiang, H. C.; Hanson, D.; Conley, A.; Bleem, L. E.; Stark, A. A.; Schulz, B.; Zemcov, M.; George, E. M.; Reichardt, C. L.; Aird, K. A.; Benson, B. A.; Carlstrom, J. E.; Chang, C. L.; Cho, H. -M.; Crawford, T. M.; de Haan, T.; Dobbs, M. A.; Halverson, N. W.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Keisler, R.; Knox, L.; Lee, A. T.; Luong-Van, D.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Montroy, T. E.; Padin, S.; Pryke, C.; Ruhl, J. E.; Schaffer, K. K.; Story, K. T.; Vanderlinde, K.; Vieira, J. D.; Zahn, O.; Li, D.; Tucker, C.; Hoover, S.; Natoli, T.; Bender, A. N.; Marsden, G.; Austermann, J. E.; Beall, J. A.; Hilton, G. C.; Hubmayr, J.; Harrington, N.; Sayre, J. T.; Irwin, K. D.; Henning, J. W.; Everett, W.; Gallicchio, J.; Gao, J.; Huang, N.; Liang, C.; Mocanu, L.; Nibarger, J. P.; Novosad, V.; Saliwanchik, B. R.; Smecher, G.; Wang, G.; Yefremenko, V.; Viero, M. P.; Leitch, E.; Crites, A.
Canada, United States, United Kingdom, South Africa
Abstract
Gravitational lensing of the cosmic microwave background generates a curl pattern in the observed polarization. This “B-mode” signal provides a measure of the projected mass distribution over the entire observable Universe and also acts as a contaminant for the measurement of primordial gravity-wave signals. In this Letter we present the first detection of gravitational lensing B modes, using first-season data from the polarization-sensitive receiver on the South Pole Telescope (SPTpol). We construct a template for the lensing B-mode signal by combining E-mode polarization measured by SPTpol with estimates of the lensing potential from a Herschel-SPIRE map of the cosmic infrared background. We compare this template to the B modes measured directly by SPTpol, finding a nonzero correlation at 7.7σ significance. The correlation has an amplitude and scale dependence consistent with theoretical expectations, is robust with respect to analysis choices, and constitutes the first measurement of a powerful cosmological observable.