Planck 2018 results

IX. Constraints on primordial non-Gaussianity

¹ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris-Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
² APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/lrfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
³ African Institute for Mathematical Sciences, 6-8 Melrose Road, Muizenberg, Cape Town, South Africa
⁴ Astrophysics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
⁵ Astrophysics & Cosmology Research Unit, School of Mathematics, Statistics & Computer Science, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa
⁶ CITA, University of Toronto, 60 St. George St., Toronto, ON M5S 3H8, Canada
⁷ CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse cedex 4, France
⁸ California Institute of Technology, Pasadena, CA, USA
⁹ Centre for Theoretical Cosmology, DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
¹⁰ Computational Cosmology Center, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
¹¹ Département de Physique Théorique, Université de Genève, 24 quai E. Ansermet, 1211 Genève 4, Switzerland
¹² Département de Physique, École normale supérieure, PSL Research University, CNRS, 24 rue Lhomond, 75005 Paris, France
¹³ Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
¹⁴ Departamento de Física, Universidad de Oviedo, C/ Federico García Lorca, 18, Oviedo, Spain
¹⁵ Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
¹⁶ Department of General Education, National Institute of Technology, Kagawa College, 355 Chokushi-cho, Takamatsu, Kagawa 761-8058, Japan
¹⁷ Department of Mathematics, University of Stellenbosch, Stellenbosch 7602, South Africa
¹⁸ Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada
¹⁹ Department of Physics & Astronomy, University of the Western Cape, Cape Town 7535, South Africa
²⁰ Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK
²¹ Department of Physics, Gustaf Hällströmin katu 2a, University of Helsinki, Helsinki, Finland
²² Department of Physics, Princeton University, Princeton, NJ, USA
²³ Department of Physics, University of California, Santa Barbara, CA, USA
²⁴ Dipartimento di Fisica e Astronomia G. Galilei, Università degli Studi di Padova, Via Marzolo 8, 35131 Padova, Italy
²⁵ Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via Saragat 1, 44122 Ferrara, Italy
²⁶ Dipartimento di Fisica, Università La Sapienza, P.le A. Moro 2, Roma, Italy
²⁷ Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria, 16, Milano, Italy
²⁸ Dipartimento di Fisica, Università degli Studi di Trieste, Via A. Valerio 2, Trieste, Italy
²⁹ Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 1, Roma, Italy
³⁰ European Space Agency, ESAC, Planck Science Office, Camino bajo del Castillo, s/n, Urbanización Villafranca del Castillo, Villanueva de la Cañada, Madrid, Spain
³¹ European Space Agency, ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
³² Gran Sasso Science Institute, INFN, viale F. Crispi 7, 67100 L’Aquila, Italy
³³ HEP Division, Argonne National Laboratory, Lemont, IL 60439, USA
³⁴ Haverford College Astronomy Department, 370 Lancaster Avenue, Haverford, PA, USA
³⁵ Helsinki Institute of Physics, Gustaf Hällströmin katu 2, University of Helsinki, Helsinki, Finland
³⁶ INAF – OAS Bologna, Istituto Nazionale di Astrofisica – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Area della Ricerca del CNR, Via Gobetti 101, 40129 Bologna, Italy
³⁷ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova, Italy
³⁸ INAF – Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, Trieste, Italy
³⁹ INAF, Istituto di Radioastronomia, Via Piero Gobetti 101, 40129 Bologna, Italy
⁴⁰ INAF/IASF Milano, Via E. Bassini 15, Milano, Italy
⁴¹ INFN – CNAF, viale Berti Pichat 6/2, 40127 Bologna, Italy
⁴² INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
⁴³ INFN, Sezione di Ferrara, Via Saragat 1, 44122 Ferrara, Italy
⁴⁴ INFN, Sezione di Milano, Via Celoria 16, Milano, Italy
⁴⁵ INFN, Sezione di Roma 1, Università di Roma Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
⁴⁶ INFN, Sezione di Roma 2, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 1, Roma, Italy
⁴⁷ Imperial College London, Astrophysics group, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
⁴⁸ Institut d’Astrophysique Spatiale, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Bât. 121, 91405 Orsay cedex, France
⁴⁹ Institut d’Astrophysique de Paris, CNRS (UMR7095), 98bis boulevard Arago, 75014 Paris, France
⁵⁰ Institute Lorentz, Leiden University, PO Box 9506, 2300 RA Leiden, The Netherlands
⁵¹ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁵² Institute of Theoretical Astrophysics, University of Oslo, Blindern, Oslo, Norway
⁵³ Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, La Laguna, Tenerife, Spain
⁵⁴ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
⁵⁵ Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, Santander, Spain
⁵⁶ Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Via Marzolo 8, 35131 Padova, Italy
⁵⁷ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, USA
⁵⁸ Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁵⁹ Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁶⁰ Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), UTIAS, The University of Tokyo, Chiba 277- 8583, Japan
⁶¹ Laboratoire d’Océanographie Physique et Spatiale (LOPS), Univ. Brest, CNRS, Ifremer, IRD, Brest, France
⁶² Laboratoire de Physique Subatomique et Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex, France
⁶³ Laboratoire de Physique Théorique, Université Paris-Sud 11 & CNRS, Bâtiment 210, 91405 Orsay, France
⁶⁴ Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo 00076, Finland
⁶⁵ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
⁶⁶ Mullard Space Science Laboratory, University College London, Surrey RH5 6NT, UK
⁶⁷ NAOC-UKZN Computational Astrophysics Centre (NUCAC), University of KwaZulu-Natal, Durban 4000, South Africa
⁶⁸ National Centre for Nuclear Research, ul. L. Pasteura 7, 02-093 Warsaw, Poland
⁶⁹ Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada
⁷⁰ Purple Mountain Observatory, No. 8 Yuan Hua Road, 210034 Nanjing, PR China
⁷¹ SISSA, Astrophysics Sector, Via Bonomea 265, 34136 Trieste, Italy
⁷² San Diego Supercomputer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla CA, 92093, USA
⁷³ School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa
⁷⁴ School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA, UK
⁷⁵ School of Physics and Astronomy, Sun Yat-sen University, 2 Daxue Rd, Tangjia, Zhuhai, PR China
⁷⁶ School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
⁷⁷ School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram, 695551 Kerala, India
⁷⁸ School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
⁷⁹ Simon Fraser University, Department of Physics, 8888 University Drive, Burnaby, BC, Canada
⁸⁰ Sorbonne Université, Observatoire de Paris, Université PSL, École normale supérieure, CNRS, LERMA, 75005 Paris, France
⁸¹ Sorbonne Université, UMR7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
⁸² Space Research Institute (IKI), Russian Academy of Sciences, Profsoyuznaya Str, 84/32, Moscow 117997, Russia
⁸³ Space Science Data Center – Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
⁸⁴ Space Sciences Laboratory, University of California, Berkeley, CA, USA
⁸⁵ The Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, AlbaNova, 106 91 Stockholm, Sweden
⁸⁶ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse Cedex 4, France
⁸⁷ Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
⁸⁸ Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland

Received: 15 May 2019
Accepted: 5 November 2019

Abstract

We analyse the Planck full-mission cosmic microwave background (CMB) temperature and E-mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained from separable template-fitting, binned, and optimal modal bispectrum estimators, finding consistent values for the local, equilateral, and orthogonal bispectrum amplitudes. Our combined temperature and polarization analysis produces the following final results: f_NL^local = −0.9 ± 5.1; f_NL^equil = −26 ± 47; and f_NL^ortho = −38 ± 24 (68% CL, statistical). These results include low-multipole (4 ≤ ℓ <  40) polarization data that are not included in our previous analysis. The results also pass an extensive battery of tests (with additional tests regarding foreground residuals compared to 2015), and they are stable with respect to our 2015 measurements (with small fluctuations, at the level of a fraction of a standard deviation, which is consistent with changes in data processing). Polarization-only bispectra display a significant improvement in robustness; they can now be used independently to set primordial NG constraints with a sensitivity comparable to WMAP temperature-based results and they give excellent agreement. In addition to the analysis of the standard local, equilateral, and orthogonal bispectrum shapes, we consider a large number of additional cases, such as scale-dependent feature and resonance bispectra, isocurvature primordial NG, and parity-breaking models, where we also place tight constraints but do not detect any signal. The non-primordial lensing bispectrum is, however, detected with an improved significance compared to 2015, excluding the null hypothesis at 3.5σ. Beyond estimates of individual shape amplitudes, we also present model-independent reconstructions and analyses of the Planck CMB bispectrum. Our final constraint on the local primordial trispectrum shape is g_NL^local = (−5.8 ± 6.5) × 10⁴ (68% CL, statistical), while constraints for other trispectrum shapes are also determined. Exploiting the tight limits on various bispectrum and trispectrum shapes, we constrain the parameter space of different early-Universe scenarios that generate primordial NG, including general single-field models of inflation, multi-field models (e.g. curvaton models), models of inflation with axion fields producing parity-violation bispectra in the tensor sector, and inflationary models involving vector-like fields with directionally-dependent bispectra. Our results provide a high-precision test for structure-formation scenarios, showing complete agreement with the basic picture of the ΛCDM cosmology regarding the statistics of the initial conditions, with cosmic structures arising from adiabatic, passive, Gaussian, and primordial seed perturbations.