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A Measurement of the Damping Tail of the Cosmic Microwave Background Power Spectrum with the South Pole Telescope

Keisler, R. and Lueker, M. and Padin, S. and Vieira, J. D. (2011) A Measurement of the Damping Tail of the Cosmic Microwave Background Power Spectrum with the South Pole Telescope. Astrophysical Journal, 743 (1). p. 28. ISSN 0004-637X.

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We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) using data from the South Pole Telescope (SPT). The data consist of 790 deg^2 of sky observed at 150 GHz during 2008 and 2009. Here we present the power spectrum over the multipole range 650 < ℓ < 3000, where it is dominated by primary CMB anisotropy. We combine this power spectrum with the power spectra from the seven-year Wilkinson Microwave Anisotropy Probe (WMAP) data release to constrain cosmological models. We find that the SPT and WMAP data are consistent with each other and, when combined, are well fit by a spatially flat, ΛCDM cosmological model. The SPT+WMAP constraint on the spectral index of scalar fluctuations is n_s = 0.9663 ± 0.0112. We detect, at ~5σ significance, the effect of gravitational lensing on the CMB power spectrum, and find its amplitude to be consistent with the ΛCDM cosmological model. We explore a number of extensions beyond the ΛCDM model. Each extension is tested independently, although there are degeneracies between some of the extension parameters. We constrain the tensor-to-scalar ratio to be r < 0.21 (95% CL) and constrain the running of the scalar spectral index to be dn_s /dln k = –0.024 ± 0.013. We strongly detect the effects of primordial helium and neutrinos on the CMB; a model without helium is rejected at 7.7σ, while a model without neutrinos is rejected at 7.5σ. The primordial helium abundance is measured to be Y_p = 0.296 ± 0.030, and the effective number of relativistic species is measured to be N_eff = 3.85 ± 0.62. The constraints on these models are strengthened when the CMB data are combined with measurements of the Hubble constant and the baryon acoustic oscillation feature. Notable improvements include ns = 0.9668 ± 0.0093, r < 0.17 (95% CL), and N_eff = 3.86 ± 0.42. The SPT+WMAP data show a mild preference for low power in the CMB damping tail, and while this preference may be accommodated by models that have a negative spectral running, a high primordial helium abundance, or a high effective number of relativistic species, such models are disfavored by the abundance of low-redshift galaxy clusters.

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Additional Information:© 2011 American Astronomical Society. Received 2011 May 16; accepted 2011 September 22; published 2011 November 18. 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. We acknowledge use of the FNAL-KICP Joint Cluster. R. Keisler acknowledges support from 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 NSF grant AST-1009811. M. Millea and L. Knox acknowledge the support of NSF grant 0709498. 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. 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.
Funding AgencyGrant Number
National Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Research Chairs programUNSPECIFIED
Canadian Institute for Advanced Research (CIAR)UNSPECIFIED
NASA Hubble Fellowship grantHF-51275.01
Alfred P. Sloan Research FellowshipUNSPECIFIED
Yale UniversityUNSPECIFIED
Subject Keywords:cosmic background radiation; cosmological parameters; cosmology: observations
Issue or Number:1
Record Number:CaltechAUTHORS:20120201-100844075
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Official Citation:A Measurement of the Damping Tail of the Cosmic Microwave Background Power Spectrum with the South Pole Telescope R. Keisler et al. 2011 ApJ 743 28
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29062
Deposited By: Jason Perez
Deposited On:01 Feb 2012 19:30
Last Modified:03 Oct 2019 03:38

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