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Non-Gaussianity in WMAP data due to the correlation of CMB lensing potential with secondary anisotropies

Calabrese, Erminia, Smidt, Joseph, Amblard, Alexandre, Cooray, Asantha, Melchiorri, Alessandro, Serra, Paolo, Heavens, Alan and Munshi, Dipak 2010. Non-Gaussianity in WMAP data due to the correlation of CMB lensing potential with secondary anisotropies. Physical Review D 81 (4) , 043529. 10.1103/PhysRevD.81.043529

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We measure the skewness power spectrum of the CMB anisotropies optimized for a detection of the secondary bispectrum generated by the correlation of the CMB lensing potential with integrated SachsWolfe effect and the Sunyaev-Zel’dovich effect. The covariance of our measurements is generated by Monte Carlo simulations of Gaussian CMB fields with noise properties consistent with WMAP 5-year data. When interpreting multifrequency measurements we also take into account the confusion resulting from unresolved radio point sources. We analyze Q, V and W-band WMAP 5-year raw and foregroundcleaned maps using the KQ75 mask out to lmax ¼ 600. We find no significant evidence for a nonzero nonGaussian signal from the lensing-secondary correlation in all three bands and we constrain the overall amplitude of the cross-power spectrum between CMB lensing potential and the sum of SZ and ISW fluctuations to be 0:42 � 0:86 and 1:19 � 0:86 in combined V and W-band raw and foreground-cleaned maps provided by the WMAP team, respectively. The point-source amplitude at the bispectrum level measured with this skewness power spectrum is higher than previous measurements of point-source nonGaussianity. We also consider an analysis where we also account for the primordial non-Gaussianity in addition to lensing-secondary bispectrum and point sources. The focus of this paper is on secondary anisotropies. Consequently the estimator is not optimized for primordial non-Gaussianity and the limit we find on local non-Gaussianity from the foreground-cleaned V þ W maps is fNL ¼ 13 � 62, when marginalized over point sources and lensing-ISW/SZ contributions to the total bispectrum.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Publisher: American Physical Society
ISSN: 1550-7998
Date of First Compliant Deposit: 10 October 2017
Date of Acceptance: 25 September 2009
Last Modified: 11 Oct 2017 12:16

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