Bayesian Power Spectrum Analysis of the First-Year Wilkinson Microwave Anisotropy Probe Data
Published 2004 November 22 •
© 2004. The American Astronomical Society. All rights reserved. Printed in U.S.A.
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Citation I. J. O’Dwyer et al 2004 ApJ 617 L99DOI 10.1086/427386
I. J. O’Dwyer
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Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801-3080
H. K. Eriksen
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Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo, Norway
Centre of Mathematics for Applications, University of Oslo, P.O. Box 1053, Blindern, N-0316 Oslo, Norway
Jet Propulsion Laboratory, California Institute of Technology, M/S 169/327, 4800 Oak Grove Drive, Pasadena, CA 91109
California Institute of Technology, Pasadena, CA 91125
B. D. Wandelt
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Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801-3080
Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801-3080
J. B. Jewell
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Jet Propulsion Laboratory, California Institute of Technology, M/S 169/327, 4800 Oak Grove Drive, Pasadena, CA 91109
D. L. Larson
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Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801-3080
K. M. Górski
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Jet Propulsion Laboratory, California Institute of Technology, M/S 169/327, 4800 Oak Grove Drive, Pasadena, CA 91109
California Institute of Technology, Pasadena, CA 91125
Warsaw University Observatory, Aleje Ujazdowskie 4, PL-00-478 Warsaw, Poland
A. J. Banday
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Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, Postfach 1317, D-85741 Garching bei München, Germany
S. Levin
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Jet Propulsion Laboratory, California Institute of Technology, M/S 169/327, 4800 Oak Grove Drive, Pasadena, CA 91109
P. B. Lilje
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Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo, Norway
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Dates
- Received 2004 July 2
- Accepted 2004 November 11
- Published 2004 November 22
Abstract
We present the first results from a Bayesian analysis of the Wilkinson Microwave Anisotropy Probe (WMAP) first-year data using a Gibbs sampling technique. Using two independent, parallel supercomputer codes, we analyze the WMAP Q, V, and W bands. The analysis results in a full probabilistic description of the information the WMAP data set contains about the power spectrum and the all-sky map of the cosmic microwave background anisotropies. We present the complete probability distributions for each Cℓ, including any non-Gaussianities of the power spectrum likelihood. While we find good overall agreement with the previously published WMAP spectrum, our analysis uncovers discrepancies in the power spectrum estimates at low-ℓ multipoles. For example, we claim that the best-fit ΛCDM model is consistent with the C2 inferred from our combined Q+V+W analysis, with a 10% probability of an even larger theoretical C2. Based on our exact analysis, we can therefore attribute the "low-quadrupole issue" to a statistical fluctuation.