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Published July 10, 2015 | Submitted + Published
Journal Article Open

Measurements of Sub-degree B-mode Polarization in the Cosmic Microwave Background from 100 Square Degrees of SPTpol Data

Abstract

We present a measurement of the B-mode polarization power spectrum (the BB spectrum) from 100 deg^2 of sky observed with SPTpol, a polarization-sensitive receiver currently installed on the South Pole Telescope. The observations used in this work were taken during 2012 and early 2013 and include data in spectral bands centered at 95 and 150 GHz. We report the BB spectrum in five bins in multipole space, spanning the range 300 ≤ ℓ ≤ 2300, and for three spectral combinations: 95 GHz × 95 GHz, 95 GHz × 150 GHz, and 150 GHz × 150 GHz. We subtract small (<0.5σ in units of statistical uncertainty) biases from these spectra and account for the uncertainty in those biases. The resulting power spectra are inconsistent with zero power but consistent with predictions for the BB spectrum arising from the gravitational lensing of E-mode polarization. If we assume no other source of BB power besides lensed B modes, we determine a preference for lensed B modes of 4.9σ. After marginalizing over tensor power and foregrounds, namely, polarized emission from galactic dust and extragalactic sources, this significance is 4.3σ. Fitting for a single parameter, A_(lens), that multiplies the predicted lensed B-mode spectrum, and marginalizing over tensor power and foregrounds, we find A_(lens) = 1.08 ± 0.26, indicating that our measured spectra are consistent with the signal expected from gravitational lensing. The data presented here provide the best measurement to date of the B-mode power spectrum on these angular scales.

Additional Information

© 2015 The American Astronomical Society. Received 2015 March 9; accepted 2015 May 28; published 2015 July 9. The South Pole Telescope program is supported by the National Science Foundation through grant PLR-1248097. Partial support is also provided by the NSF Physics Frontier Center grant 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 GBMF#947 to the University of Chicago. The McGill authors acknowledge funding from the Natural Sciences and Engineering Research Council of Canada, Canadian Institute for Advanced Research, and Canada Research Chairs program. J.W.H. is supported by the National Science Foundation under Award No. AST-1402161. B.B. is supported by the Fermi Research Alliance, LLC, under Contract No. De-AC02-07CH11359 with the U.S. Department of Energy. The CU Boulder group acknowledges support from NSF AST-0956135. This work is also supported by the U.S. Department of Energy. 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, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. The data analysis pipeline uses the scientific python stack (Jones et al. 2001; Hunter 2007; van der Walt et al. 2011) and the HDF5 file format (The HDF Group 1997).

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Published - 0004-637X_807_2_151.pdf

Submitted - 1503.02315v1.pdf

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August 22, 2023
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October 24, 2023