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.

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Available from: Giancarlo de Gasperis
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    • "The investigation of the stochastic properties of needlets when implemented on spherical random fields is due to [3], [4], [43], [44] and [49], where applications to several statistical procedures are also considered. These procedures have been mainly motivated by issues arising in Cosmology and Astrophysics, and indeed several applications to experimental data have already been implemented: for instance, those from the satellite WMAP mission from NASA, focussing on the so-called Cosmic Microwave Background radiation, see [55], [48], [56], [18], [57], [58], [14], [59], [11] and [31]. These applications, however, have not been focussed on thresholding estimates and minimax results, but rather to random fields issues, such as angular power spectrum estimation, higher-order spectra, testing for Gaussianity and isotropy, and several others (see also [47],[13]). "
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