We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using the SPTpol instrument on the South Pole Telescope. This work uses 500 deg2 of SPTpol data, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: 52< <2301. Data from both 95 and 150 GHz are used, allowing for three cross-spectra: 95 GHz × 95 GHz, 95 GHz × 150 GHz, and 150 GHz × 150 GHz. B-mode power is detected at very high significance; we find P(BB<0)=5.8×10-71, corresponding to a 18.1σ detection of power. With a prior on the galactic dust from Planck, WMAP and BICEP2/Keck observations, the SPTpol B-mode data can be used to set an upper limit on the tensor-to-scalar ratio, r<0.44 at 95% confidence (the expected 1σ constraint on r given the measurement uncertainties is 0.22). We find the measured B-mode power is consistent with the Planck best-fit ΛCDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor Alens, the data prefer Alens=1.17±0.13. These data are currently the most precise measurements of B-mode power at >320.
Bibliographical noteFunding Information:
The South Pole Telescope program is supported by the National Science Foundation through Grant No. PLR-1248097. Partial support is also provided by the NSF Physics Frontier Center Grant No. PHY-0114422 to the Kavli Institute of Cosmological Physics at the University of Chicago, the Kavli Foundation, and the Gordon and Betty Moore Foundation through Grant No. GBMF#947 to the University of Chicago. This work is also supported by the U.S. Department of Energy. The Melbourne authors acknowledge support from an Australian Research Council Future Fellowship (No. FT150100074). J. W. H. is supported by the National Science Foundation under Award No. AST-1402161. W. L. K.W is supported in part by the Kavli Institute for Cosmological Physics at the University of Chicago through Grant No. NSF PHY-1125897 and an endowment from the Kavli Foundation and its founder Fred Kavli. B. B. is supported by the Fermi Research Alliance LLC under Contract No. De-AC02-07CH11359 with the U.S. Department of Energy. The Cardiff authors acknowledge support from the UK Science and Technologies Facilities Council (STFC). The CU Boulder group acknowledges support from NSF Grant No. AST-0956135. The McGill authors acknowledge funding from the Natural Sciences and Engineering Research Council of Canada, Canadian Institute for Advanced Research, and the Fonds de Recherche du Québec—Nature et technologies. The UCLA authors acknowledge support from NSF Grants No. AST-1716965 and No. CSSI-1835865. Work at Argonne National Lab is supported by UChicago Argonne LLC,Operator of Argonne National Laboratory (Argonne). Argonne, a U.S. Department of Energy Office of Science Laboratory, is operated under Contract No. DE-AC02-06CH11357. We also acknowledge support from the Argonne Center for Nanoscale Materials. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. The data analysis pipeline also uses the scientific python stack and the HDF5 file format .