Planck intermediate results. XLI. A map of lensing-induced B-modes

Abstract : The lensing-induced $B$-mode signal is a valuable probe of the dark matter distribution integrated back to the last-scattering surface, with a broad kernel that peaks at $z\simeq2$. It also constitutes an important contaminant for the extraction of the primary CMB $B$-modes from inflation. Combining all-sky coverage and high resolution and sensitivity, Planck provides accurate nearly all-sky measurements of both the polarization $E$-mode signal and the integrated mass distribution via the reconstruction of the CMB gravitational lensing. By combining these two data products, we have produced an all-sky template map of the secondary CMB $B$-modes using a real-space algorithm that minimizes the impact of sky masks. The cross-correlation of this template with an observed (primordial and secondary) $B$-mode map can be used to measure the lensing $B$-mode power spectrum at all angular scales. In particular when cross-correlating with the $B$-mode contribution directly derived from the Planck polarization maps, we obtain lensing-induced $B$-mode power spectrum measurements at a significance of $12\,\sigma$, which are in agreement with the theoretical expectation derived from the \Planck\ best-fit $\Lambda$CDM model. This unique nearly all-sky secondary $B$-mode template, which includes the lensing-induced information from intermediate to small ($10\lesssim \ell\lesssim 1000$) angular scales, is delivered as part of the Planck 2015 public data release. It will be particularly useful for experiments searching for primordial $B$-modes, such as BICEP2/Keck Array or LiteBIRD, since it will enable an estimate to be made of the secondary (i.e., lensing) contribution to the measured total CMB $B$-modes.
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Article dans une revue
Astronomy and Astrophysics - A&A, EDP Sciences, 2016, 596, pp.A102. 〈10.1051/0004-6361/201527932 〉
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Soumis le : jeudi 10 décembre 2015 - 10:53:39
Dernière modification le : jeudi 11 janvier 2018 - 06:14:22

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P. A. R. Ade, O. Perdereau, M. Tristram, A. Catalano, C. Combet, et al.. Planck intermediate results. XLI. A map of lensing-induced B-modes. Astronomy and Astrophysics - A&A, EDP Sciences, 2016, 596, pp.A102. 〈10.1051/0004-6361/201527932 〉. 〈in2p3-01241228〉



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