<i>Planck</i>2018 results

Abstract

We report on the implications for cosmic inflation of the 2018 release of the Planck cosmic microwave background (CMB) anisotropy measurements. The results are fully consistent with those reported using the data from the two previous Planck cosmological releases, but have smaller uncertainties thanks to improvements in the characterization of polarization at low and high multipoles. Planck temperature, polarization, and lensing data determine the spectral index of scalar perturbations to be n s = 0.9649 ± 0.0042 at 68% CL. We find no evidence for a scale dependence of n s , either as a running or as a running of the running. The Universe is found to be consistent with spatial flatness with a precision of 0.4% at 95% CL by combining Planck with a compilation of baryon acoustic oscillation data. The Planck 95% CL upper limit on the tensor-to-scalar ratio, r 0.002 &lt; 0.10, is further tightened by combining with the BICEP2/Keck Array BK15 data to obtain r 0.002 &lt; 0.056. In the framework of standard single-field inflationary models with Einstein gravity, these results imply that: (a) the predictions of slow-roll models with a concave potential, V ″( ϕ ) &lt; 0, are increasingly favoured by the data; and (b) based on two different methods for reconstructing the inflaton potential, we find no evidence for dynamics beyond slow roll. Three different methods for the non-parametric reconstruction of the primordial power spectrum consistently confirm a pure power law in the range of comoving scales 0.005 Mpc −1 ≲ k ≲ 0.2 Mpc −1 . A complementary analysis also finds no evidence for theoretically motivated parameterized features in the Planck power spectra. For the case of oscillatory features that are logarithmic or linear in k , this result is further strengthened by a new combined analysis including the Planck bispectrum data. The new Planck polarization data provide a stringent test of the adiabaticity of the initial conditions for the cosmological fluctuations. In correlated, mixed adiabatic and isocurvature models, the non-adiabatic contribution to the observed CMB temperature variance is constrained to 1.3%, 1.7%, and 1.7% at 95% CL for cold dark matter, neutrino density, and neutrino velocity, respectively. Planck power spectra plus lensing set constraints on the amplitude of compensated cold dark matter-baryon isocurvature perturbations that are consistent with current complementary measurements. The polarization data also provide improved constraints on inflationary models that predict a small statistically anisotropic quadupolar modulation of the primordial fluctuations. However, the polarization data do not support physical models for a scale-dependent dipolar modulation. All these findings support the key predictions of the standard single-field inflationary models, which will be further tested by future cosmological observations.

Keywords

Affiliated Institutions

• University of California, Berkeley US
• Université Paris Cité FR
• Jet Propulsion Laboratory US
• Institut National de Physique Nucléaire et de Physique des Particules FR
• Scuola Internazionale Superiore di Studi Avanzati IT
• University of Manchester GB
• Sorbonne Université FR
• University of Padua IT
• California Institute of Technology US
• AlbaNova SE
• Aix-Marseille Université FR
• University of Toronto CA
• National Taiwan University TW
• Roche (France) FR
• Universidad de La Laguna ES
• Istituto Nazionale di Fisica Nucleare, Sezione di Bologna IT
• Polish Academy of Sciences PL
• University of Oslo
• European Space Astronomy Centre ES
• Sorbonne Paris Cité FR
• UNSW Sydney AU
• Indian Institute of Science Education and Research Thiruvananthapuram IN
• African Institute for Mathematical Sciences ZA
• Stellenbosch University ZA
• Centre National de la Recherche Scientifique FR
• Universidad de Oviedo ES
• Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères FR
• Instituto de Física de Cantabria ES
• Helsinki Institute of Physics FI
• Institut d'Astrophysique Spatiale FR
• Istituto di Radioastronomia di Bologna IT
• Osservatorio Astronomico di Padova IT
• Imperial College London GB
• National Institute of Science Education and Research IN
• Universidad de Cantabria ES
• University of Helsinki FI
• University of California, Santa Barbara US
• Istituto Nazionale di Fisica Nucleare, Sezione di Padova IT
• University of Sussex GB
• Université Paris-Saclay FR
• Cardiff University GB
• Trieste Astronomical Observatory IT
• Université Paris Sciences et Lettres FR
• Commissariat à l'Énergie Atomique et aux Énergies Alternatives FR
• University of Ferrara IT
• Université Toulouse III - Paul Sabatier FR
• University of Milan IT
• Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna IT
• Lawrence Berkeley National Laboratory US
• Nicolaus Copernicus Astronomical Center PL
• University of Cambridge GB
• Université Paris-Sud FR
• University of Geneva CH
• University of British Columbia CA
• Sun Yat-sen University CN
• University of KwaZulu-Natal ZA
• Leiden University NL
• University of Lisbon PT
• Stockholm University SE
• RWTH Aachen University DE
• University of the Western Cape ZA
• Simon Fraser University CA
• Université Grenoble Alpes FR
• Instituto de Astrofísica de Canarias ES
• University of Chicago US
• Osservatorio di Astrofisica e Scienza dello Spazio
• Institute of Astrophysics and Space Sciences PT
• Max Planck Institute for Astrophysics DE
• Institut d'Astrophysique de Paris FR
• Princeton University US
• Sapienza University of Rome IT
• Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara IT
• Observatoire de Paris FR
• University of Warsaw PL
• Université Fédérale de Toulouse Midi-Pyrénées FR
• National Institute for Astrophysics IT

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