Planck2018 results
Authors:   Planck Collaboration, Akrami Y. , Ashdown M. , Aumont J. , Baccigalupi C. , Ballardini M. , Banday A. J. , Barreiro R. B. , Bartolo N. , Basak S. , Benabed K. , Bernard J.-P. , Bersanelli M. , Bielewicz P. , Bond J. R. , Borrill J. , Bouchet F. R. , Boulanger F. , Bracco A. , Bucher M. , Burigana C. , Calabrese E. , Cardoso J.-F. , Carron J. , Chiang H. C. , Combet C. , Crill B. P. , de Bernardis P. , de Zotti G. , Delabrouille J. , Delouis J.-M. , Di Valentino E. , Dickinson C. , Diego J. M. , Ducout A. , Dupac X. , Efstathiou G. , Elsner F. , Enßlin T. A. , Falgarone E. , Fantaye Y. , Ferrière K. , Finelli F. , Forastieri F. , Frailis M. , Fraisse A. A. , Franceschi E. , Frolov A. , Galeotta S. , Galli S. , Ganga K. , Génova-Santos R. T. , Ghosh T. , González-Nuevo J. , Górski K. M. , Gruppuso A. , Gudmundsson J. E. , Guillet V. , Handley W. , Hansen F. K. , Herranz D. , Huang Z. , Jaffe A. H. , Jones W. C. , Keihänen E. , Keskitalo R. , Kiiveri K. , Kim J. , Krachmalnicoff N. , Kunz M. , Kurki-Suonio H. , Lamarre J.-M. , Lasenby A. , Le Jeune M. , Levrier F. , Liguori M. , Lilje P. B. , Lindholm V. , López-Caniego M. , Lubin P. M. , Ma Y.-Z. , Macías-Pérez J. F. , Maggio G. , Maino D. , Mandolesi N. , Mangilli A. , Martin P. G. , Martínez-González E. , Matarrese S. , McEwen J. D. , Meinhold P. R. , Melchiorri A. , Migliaccio M. , Miville-Deschênes M.-A. , Molinari D. , Moneti A. , Montier L. , Morgante G. , Natoli P. , Pagano L. , Paoletti D. , Pettorino V. , Piacentini F. , Polenta G. , Puget J.-L. , Rachen J. P. , Reinecke M. , Remazeilles M. , Renzi A. , Rocha G. , Rosset C. , Roudier G. , Rubiño-Martín J. A. , Ruiz-Granados B. , Salvati L. , Sandri M. , Savelainen M. , Scott D. , Soler J. D. , Spencer L. D. , Tauber J. A. , Tavagnacco D. , Toffolatti L. , Tomasi M. , Trombetti T. , Valiviita J. , Vansyngel F. , Van Tent B. , Vielva P. , Villa F. , Vittorio N. , Wehus I. K. , Zacchei A. , Zonca A. 
Published: April 2019

The study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (CMB) polarization in the quest for the curl-likeB-mode polarization from primordial gravitational waves and the low-multipoleE-mode polarization associated with the reionization of the Universe. We used the newPlanckPR3 maps to characterize Galactic dust emission at high latitudes as a foreground to the CMB polarization and use end-to-end simulations to compute uncertainties and assess the statistical significance of our measurements. We presentPlanckEE,BB, andTEpower spectra of dust polarization at 353 GHz for a set of six nested high-Galactic-latitude sky regions covering from 24 to 71% of the sky. We present power-law fits to the angular power spectra, yielding evidence for statistically significant variations of the exponents over sky regions and a difference between the values for theEEandBBspectra, which for the largest sky region areαEE = −2.42 ± 0.02 andαBB = −2.54 ± 0.02, respectively. The spectra show that theTEcorrelation andE/Bpower asymmetry discovered byPlanckextend to low multipoles that were not included in earlierPlanckpolarization papers due to residual data systematics. We also report evidence for a positiveTBdust signal. Combining data fromPlanckand WMAP, we have determined the amplitudes and spectral energy distributions (SEDs) of polarized foregrounds, including the correlation between dust and synchrotron polarized emission, for the six sky regions as a function of multipole. This quantifies the challenge of the component-separation procedure that is required for measuring the low-ℓreionization CMBE-mode signal and detecting the reionization and recombination peaks of primordial CMBBmodes. The SED of polarized dust emission is fit well by a single-temperature modified black-body emission law from 353 GHz to below 70 GHz. For a dust temperature of 19.6 K, the mean dust spectral index for dust polarization isβdP= 1.53±0.02. The difference between indices for polarization and total intensity isβdP−βdI= 0.05±0.03. By fitting multi-frequency cross-spectra betweenPlanckdata at 100, 143, 217, and 353 GHz, we examine the correlation of the dust polarization maps across frequency. We find no evidence for a loss of correlation and provide lower limits to the correlation ratio that are tighter than values we derive from the correlation of the 217- and 353 GHz maps alone. If thePlancklimit on decorrelation for the largest sky region applies to the smaller sky regions observed by sub-orbital experiments, then frequency decorrelation of dust polarization might not be a problem for CMB experiments aiming at a primordialB-mode detection limit on the tensor-to-scalar ratior ≃ 0.01 at the recombination peak. However, thePlancksensitivity precludes identifying how difficult the component-separation problem will be for more ambitious experiments targeting lower limits onr.