Bayesian Power Spectrum Analysis of the First-Year WMAP data
Abstract
We present the first results from a Bayesian analysis of the 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 C_l 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 the best-fit Lambda-CDM model is consistent with the C_2 inferred from our combined Q+V+W analysis with a 10% probability of an even larger theoretical C_2. Based on our exact analysis we can therefore attribute the "low quadrupole issue" to a statistical fluctuation.
Cite
@article{arxiv.astro-ph/0407027,
title = {Bayesian Power Spectrum Analysis of the First-Year WMAP data},
author = {I. J. O'Dwyer and H. K. Eriksen and B. D. Wandelt and J. B. Jewell and D. L. Larson and K. M. Gorski and A. J. Banday and S. Levin and P. B. Lilje},
journal= {arXiv preprint arXiv:astro-ph/0407027},
year = {2009}
}
Comments
5 pages. 4 figures. For additional information and data see http://www.astro.uiuc.edu/~iodwyer/research#wmap