Wilkinson Microwave Anisotropy Probe 5-yr constraints on fnl with wavelets |
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| Authors: | A Curto E Martínez-González P Mukherjee R B Barreiro F K Hansen M Liguori S Matarrese |
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| Institution: | Instituto de Física de Cantabria, CSIC-Universidad de Cantabria, Avda. de los Castros s/n, 39005 Santander, Spain;Dpto. de Física Moderna, Universidad de Cantabria, Avda. los Castros s/n, 39005 Santander, Spain;Astronomy Centre, University of Sussex, Brighton BN1 9QH;Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway;Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberfoce Road, Cambridge CB3 0WA;Dipartimento di Fisica G. Galilei, Universitàdi Padova and INFN, Sezione di Padova, via Marzolo 8, I-35131, Padova, Italy |
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| Abstract: | We present a Gaussianity analysis of the Wilkinson Microwave Anisotropy Probe ( WMAP ) 5-yr cosmic microwave background (CMB) temperature anisotropy data maps. We use several third-order estimators based on the spherical Mexican hat wavelet. We impose constraints on the local non-linear coupling parameter f nl using well-motivated non-Gaussian simulations. We analyse the WMAP maps at resolution of 6.9 arcmin for the Q , V , and W frequency bands. We use the KQ 75 mask recommended by the WMAP team which masks out 28 per cent of the sky. The wavelet coefficients are evaluated at 10 different scales from 6.9 to 150 arcmin. With these coefficients, we compute the third order estimators which are used to perform a χ2 analysis. The χ2 statistic is used to test the Gaussianity of the WMAP data as well as to constrain the f nl parameter. Our results indicate that the WMAP data are compatible with the Gaussian simulations, and the f nl parameter is constrained to ?8 < f nl < +111 at 95 per cent confidence level (CL) for the combined V + W map. This value has been corrected for the presence of undetected point sources, which add a positive contribution of Δ f nl= 3 ± 5 in the V + W map. Our results are very similar to those obtained by the WMAP team using the bispectrum. |
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| Keywords: | methods: data analysis cosmic microwave background |
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