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A Measurement of Gravitational Lensing of the Microwave Background Using South Pole Telescope Data

van Engelen, A. and Lueker, M. and Padin, S. and Vieira, J. D. (2012) A Measurement of Gravitational Lensing of the Microwave Background Using South Pole Telescope Data. Astrophysical Journal, 756 (2). Art. No. 142. ISSN 0004-637X.

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We use South Pole Telescope data from 2008 and 2009 to detect the non-Gaussian signature in the cosmic microwave background (CMB) produced by gravitational lensing and to measure the power spectrum of the projected gravitational potential. We constrain the ratio of the measured amplitude of the lensing signal to that expected in a fiducial ΛCDM cosmological model to be 0.86 ± 0.16, with no lensing disfavored at 6.3σ. Marginalizing over ΛCDM cosmological models allowed by the Wilkinson Microwave Anisotropy Probe (WMAP7) results in a measurement of A_lens = 0.90 ± 0.19, indicating that the amplitude of matter fluctuations over the redshift range 0.5 ≲ z ≲ 5 probed by CMB lensing is in good agreement with predictions. We present the results of several consistency checks. These include a clear detection of the lensing signature in CMB maps filtered to have no overlap in Fourier space, as well as a "curl" diagnostic that is consistent with the signal expected for ΛCDM. We perform a detailed study of bias in the measurement due to noise, foregrounds, and other effects and determine that these contributions are relatively small compared to the statistical uncertainty in the measurement. We combine this lensing measurement with results from WMAP7 to improve constraints on cosmological parameters when compared to those from WMAP7 alone: we find a factor of 3.9 improvement in the measurement of the spatial curvature of the universe, Ω_k = –0.0014 ± 0.0172; a 10% improvement in the amplitude of matter fluctuations within ΛCDM, σ_8 = 0.810 ± 0.026; and a 5% improvement in the dark energy equation of state, w = –1.04 ± 0.40. When compared with the measurement of w provided by the combination of WMAP7 and external constraints on the Hubble parameter, the addition of the lensing data improves the measurement of w by 15% to give w = –1.087 ± 0.096.

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Additional Information:© 2012 American Astronomical Society. Received 2012 February 3; accepted 2012 June 25; published 2012 August 23. We thank E. Anderes, S. Das, S. Dodelson, O. Doré, D. Hanson, W. Hu, and B. Sherwin for useful discussions. The South Pole Telescope is supported by the National Science Foundation through grants ANT-0638937 and ANT- 0130612. 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. The McGill group acknowledges funding from the National Sciences and Engineering Research Council of Canada, Canada Research Chairs program, and the Canadian Institute for Advanced Research. Oliver Zahn acknowledges support from an Inaugural Berkeley Center for Cosmological Physics Fellowship. R. Keisler acknowledges support from the NASA Hubble Fellowship grant HF-51275.01. B.A. Benson is supported by a KICP Fellowship. M. Dobbs acknowledges support from an Alfred P. Sloan Research Fellowship. L. Shaw acknowledges the support of Yale University and the NSF grant AST-1009811. M. Millea and L. Knox acknowledge the support of the NSF grant 0709498. J. Mohr acknowledges support from the Excellence Cluster Universe and the DFG research program TR33 “Dark Universe.” This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. It also used resources of the CLUMEQ supercomputing consortium, part of the Compute Canada network. We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA). Support for LAMBDA is provided by the NASA Office of Space Science. Some of the results in this paper have been derived using the HEALPix (Górski et al. 2005) package.
Funding AgencyGrant Number
National Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Research Chairs programUNSPECIFIED
Canadian Institute for Advanced Research (CIAR)UNSPECIFIED
Inaugural Berkeley Center for Cosmological Physics FellowshipUNSPECIFIED
NASA Hubble Fellowship grantHF-51275.01
Alfred P. Sloan Research FellowshipUNSPECIFIED
Yale UniversityUNSPECIFIED
Excellence Cluster UniverseUNSPECIFIED
DFG research program TR33 Dark UniverseUNSPECIFIED
Subject Keywords:cosmic background radiation; cosmological parameters; cosmology: observations; gravitational lensing: weak; large-scale structure of universe
Issue or Number:2
Record Number:CaltechAUTHORS:20121106-101227703
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Official Citation:A Measurement of Gravitational Lensing of the Microwave Background Using South Pole Telescope Data A. van Engelen et al. 2012 ApJ 756 142
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35299
Deposited By: Jason Perez
Deposited On:06 Nov 2012 19:30
Last Modified:03 Oct 2019 04:27

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