A Caltech Library Service

Planck 2018 results. V. CMB power spectra and likelihoods

Aghanim, N. and Ghosh, T. and Bock, J. J. and Crill, B. P. and Doré, O. and Rocha, G. (2019) Planck 2018 results. V. CMB power spectra and likelihoods. . (Unpublished)

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


This paper describes the 2018 Planck CMB likelihoods, following a hybrid approach similar to the 2015 one, with different approximations at low and high multipoles, and implementing several methodological and analysis refinements. With more realistic simulations, and better correction and modelling of systematics, we can now make full use of the High Frequency Instrument polarization data. The low-multipole 100x143 GHz EE cross-spectrum constrains the reionization optical-depth parameter τ to better than 15% (in combination with with the other low- and high-ℓ likelihoods). We also update the 2015 baseline low-ℓ joint TEB likelihood based on the Low Frequency Instrument data, which provides a weaker τ constraint. At high multipoles, a better model of the temperature-to-polarization leakage and corrections for the effective calibrations of the polarization channels (polarization efficiency or PE) allow us to fully use the polarization spectra, improving the constraints on the ΛCDM parameters by 20 to 30% compared to TT-only constraints. Tests on the modelling of the polarization demonstrate good consistency, with some residual modelling uncertainties, the accuracy of the PE modelling being the main limitation. Using our various tests, simulations, and comparison between different high-ℓ implementations, we estimate the consistency of the results to be better than the 0.5σ level. Minor curiosities already present before (differences between ℓ<800 and ℓ>800 parameters or the preference for more smoothing of the Cℓ peaks) are shown to be driven by the TT power spectrum and are not significantly modified by the inclusion of polarization. Overall, the legacy Planck CMB likelihoods provide a robust tool for constraining the cosmological model and represent a reference for future CMB observations.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Aghanim, N.0000-0002-6688-8992
Bock, J. J.0000-0002-5710-5212
Crill, B. P.0000-0002-4650-8518
Doré, O.0000-0002-5009-7563
Rocha, G.0000-0002-4150-8076
Additional Information:The Planck Collaboration acknowledges the support of: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MINECO, JA, and RES (Spain); Tekes, AoF and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and ERC and PRACE (EU). A description of the Planck Collaboration and a list of its members, indicating which technical or scientific activities they have been involved in, can be found at This research used resources of the IN2P3 Computer Center ( as well as of the Planck-HFI DPC infrastructure hosted at the Institut d’Astrophysique de Paris (France) and financially supported by CNES.
Group:Astronomy Department
Funding AgencyGrant Number
European Space Agency (ESA)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Institut National de Physique Nucléaire et de Physique des Particules (IN2P3)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Consiglio Nazionale delle Ricerche (CNR)UNSPECIFIED
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
United Kingdom Space Agency (UKSA)UNSPECIFIED
Consejo Superior de Investigaciones Científicas (CSIC)UNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)UNSPECIFIED
Junta de AndalucíaUNSPECIFIED
Spanish Supercomputing Network (RES)UNSPECIFIED
Finnish Ministry of Employment and the EconomyUNSPECIFIED
Academy of FinlandUNSPECIFIED
Finnish IT Center for Science (CSC)UNSPECIFIED
Deutsches Zentrum für Luft- und Raumfahrt (DLR)UNSPECIFIED
Max Planck SocietyUNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
State Secretariat for Education and Research (Switzerland)UNSPECIFIED
Swiss Space Office (SSO)UNSPECIFIED
Research Council of NorwayUNSPECIFIED
Science Foundation, IrelandUNSPECIFIED
Fundação para a Ciência e a Tecnologia (FCT)UNSPECIFIED
Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) UNSPECIFIED
European Research Council (ERC)UNSPECIFIED
Partnership for Advanced Computing in Europe (PRACE)UNSPECIFIED
Subject Keywords:cosmic background radiation – cosmology: observations – cosmological parameters – methods: data analysis
Record Number:CaltechAUTHORS:20190925-091335835
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98843
Deposited By: Tony Diaz
Deposited On:25 Sep 2019 17:41
Last Modified:09 Mar 2020 13:19

Repository Staff Only: item control page