Foreground influence on primordial non-Gaussianity estimates: Needlet analysis of WMAP 5-year data

Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.11). 10/2009; 405(2). DOI: 10.1111/j.1365-2966.2010.16542.x
Source: arXiv


We constrain the amplitude of primordial non-Gaussianity in the CMB data
taking into account the presence of foreground residuals in the maps. We
generalise the needlet bispectrum estimator marginalizing over the amplitudes
of thermal dust, free-free and synchrotron templates. We apply our procedure to
WMAP 5 year data, finding fNL= 38\pm 47 (1 \sigma), while the analysis without
marginalization provides fNL= 35\pm 42. Splitting the marginalization over each
foreground separately, we found that the estimates of fNL are positively cross
correlated of 17%, 12% with the dust and synchrotron respectively, while a
negative cross correlation of about -10% is found for the free-free component.


Available from: Giancarlo de Gasperis
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