Planck CollaborationAde, P. A. R.P. A. R.AdeAghanim, N.N.AghanimNatoli, PaoloPaoloNatoliPolenta, GianlucaGianlucaPolenta2020-09-172020-09-172016-12-01https://hdl.handle.net/20.500.13025/4603Astronomy & Astrophysics, Volume 596, id.A102, <NUMPAGES>19</NUMPAGES> pp.The secondary cosmic microwave background (CMB) B-modes stem from the post-decoupling distortion of the polarization E-modes due to the gravitational lensing effect of large-scale structures. These lensing-induced B-modes constitute both a valuable probe of the dark matter distribution and an important contaminant for the extraction of the primary CMB B-modes from inflation. Planck provides accurate nearly all-sky measurements of both the polarization E-modes and the integrated mass distribution via the reconstruction of the CMB lensing potential. By combining these two data products, we have produced an all-sky template map of the lensing-induced 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 multipoles up to 2000. 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 measurement at a significance level of 12sigma, which agrees with the theoretical expectation derived from the Planck best-fit Lambda cold dark matter model. This unique nearly all-sky secondary B-mode template, which includes the lensing-induced information from intermediate to small (10 ≲ l ≲ 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 lensing-induced contribution to the measured total CMB B-modes.cosmology observationscosmic background radiationpolarizationgravitational lensing weakPlanck intermediate results. XLI. A map of lensing-induced B-modes10.1051/0004-6361/201527932http://adsabs.harvard.edu/abs/2016A&A...596A.102P2016A&A...596A.102P