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Cosmic Microwave Background Constraints on the Duration and Timing of Reionization from the South Pole Telescope

Zahn, O. and Doré, O. and Lueker, M. and Padin, S. and Vieira, J. D. (2012) Cosmic Microwave Background Constraints on the Duration and Timing of Reionization from the South Pole Telescope. Astrophysical Journal, 756 (1). Art. No. 65. ISSN 0004-637X.

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The epoch of reionization is a milestone of cosmological structure formation, marking the birth of the first objects massive enough to yield large numbers of ionizing photons. However, the mechanism and timescale of reionization remain largely unknown. Measurements of the cosmic microwave background (CMB) Doppler effect from ionizing bubbles embedded in large-scale velocity streams—known as the patchy kinetic Sunyaev-Zel'dovich (kSZ) effect—can be used to constrain the duration of reionization. When combined with large-scale CMB polarization measurements, the evolution of the ionized fraction, x-bar_(e), can be inferred. Using new multi-frequency data from the South Pole Telescope (SPT), we show that the ionized fraction evolved relatively rapidly. For our basic foreground model, we find the kSZ power sourced by reionization at ℓ = 3000 to be D^(patchy)_3000 ≤ 2.1 μK^2 at 95% confidence. Using reionization simulations, we translate this to a limit on the duration of reionization of Δz≡z_(x-bar)_e=0.20 - z_(x-bar)_e=0.99≤4.4 (95% confidence). We find that this constraint depends on assumptions about the angular correlation between the thermal SZ power and the cosmic infrared background (CIB). Introducing the degree of correlation as a free parameter, we find that the limit on kSZ power weakens to D^(patchy)_3000 ≤ 4.9 μK^2, implying Δz ≤ 7.9 (95% confidence). We combine the SPT constraint on the duration of reionization with the Wilkinson Microwave Anisotropy Probe measurement of the integrated optical depth to probe the cosmic ionization history. We find that reionization ended with 95% confidence at z > 7.2 under the assumption of no tSZ-CIB correlation, and z > 5.8 when correlations are allowed. Improved constraints from the full SPT data set in conjunction with upcoming Herschel and Planck data should detect extended reionization at >95% confidence provided Δz ≥ 2. These CMB observations complement other observational probes of the epoch of reionization such as the redshifted 21 cm line and narrowband surveys for Lyα-emitting galaxies.

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Doré, O.0000-0002-5009-7563
Additional Information:© 2012 American Astronomical Society. Received 2011 November 23; accepted 2012 June 18; published 2012 August 16. We thank Matt George, Guilaine Lagache, Cien Shang, David Spergel, Marco Viero, and Matias Zaldarriaga 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. O. Zahn acknowledges support from a Berkeley Center for Cosmological Physics fellowship. 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. 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. Shawacknowledges 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. Some of the results in this paper have been derived using the HEALPix package (Górski et al. 2005). 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. We also acknowledge usage of the FFTW and TeXShop software packages.
Funding AgencyGrant Number
Berkeley Center for Cosmological PhysicsUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Research Chairs ProgramUNSPECIFIED
Canadian Institute for Advanced Research (CIFAR)UNSPECIFIED
NASA Hubble FellowshipHF-51275.01
Kavli FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Yale UniversityUNSPECIFIED
Subject Keywords:cosmology: theory; intergalactic medium; large-scale structure of universe
Issue or Number:1
Record Number:CaltechAUTHORS:20121031-140255388
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Official Citation:Cosmic Microwave Background Constraints on the Duration and Timing of Reionization from the South Pole Telescope O. Zahn et al. 2012 ApJ 756 65
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35216
Deposited By: Jason Perez
Deposited On:31 Oct 2012 22:18
Last Modified:03 Oct 2019 04:26

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