Five-Year Wilkinson Microwave Anisotropy Probe Observations: Galactic Foreground Emission

The Astrophysical Journal Supplement Series (Impact Factor: 11.22). 02/2009; 180(2):265. DOI: 10.1088/0067-0049/180/2/265
Source: arXiv


We present a new estimate of foreground emission in the Wilkinson Microwave Anisotropy Probe (WMAP) data, using a Markov chain Monte Carlo method. The new technique delivers maps of each foreground component for a variety of foreground models with estimates of the uncertainty of each foreground component, and it provides an overall goodness-of-fit estimate. The resulting foreground maps are in broad agreement with those from previous techniques used both within the collaboration and by other authors. We find that for WMAP data, a simple model with power-law synchrotron, free-free, and thermal dust components fits 90% of the sky with a reduced χ2 ν of 1.14. However, the model does not work well inside the Galactic plane. The addition of either synchrotron steepening or a modified spinning dust model improves the fit. This component may account for up to 14% of the total flux at the Ka band (33 GHz). We find no evidence for foreground contamination of the cosmic microwave background temperature map in the 85% of the sky used for cosmological analysis.

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    • "where the functions b i (ν) encode the frequency dependence of the foregrounds, and T synch ( n), T ff ( n), T dust ( n) are spatial templates for synchrotron, free-free and dust emission. For more details, including construction of the spatial templates and the procedure for estimating b i (ν), see [20]. The WMAP data release includes " clean maps " which are obtained by subtracting T fg ( n) from the " raw maps " which are directly observed in each channel. "
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