Planck 2018 results. VI. Cosmological parameters

• Published in: arXiv.org 2021-08
• Main Authors: Planck Collaboration, Aghanim, N, Ashdown, M, Ballardini, M, Benabed, K, J -P Bernard, Bersanelli, M, Bielewicz, P, Bock, J J, Bond, J R, Bouchet, F R, Burigana, C, Calabrese, E, Challinor, A, Chiang, H C, Chluba, J, Combet, C, Contreras, D, Crill, B P, de Zotti, G, J -M Delouis, E Di Valentino, Diego, J M, Douspis, M, Dupac, X, Dusini, S, Efstathiou, G, Eriksen, H K, Farhang, M, Fernandez-Cobos, R, Finelli, F, Frailis, M, Fraisse, A A, Frolov, A, Génova-Santos, R T, Gerbino, M, González-Nuevo, J, Górski, K M, Gruppuso, A, Hamann, J, Handley, W, Herranz, D, Hivon, E, Huang, Z, Jones, W C, Keskitalo, R, Kiiveri, K, Kim, J, Kisner, T S, Kunz, M, Kurki-Suonio, H, Lattanzi, M, Lawrence, C R, M Le Jeune, Lesgourgues, J, Lewis, A, Lilley, M, Lindholm, V, López-Caniego, M, Maino, D, Marcos-Caballero, A, Martínez-González, E, Matarrese, S, Melchiorri, A, Mennella, A, M -A Miville-Deschênes, Molinari, D, Moss, A, Natoli, P, Pagano, L, Paoletti, D, Partridge, B, Patanchon, G, Peiris, H V, Perrotta, F, Pettorino, V, Polastri, L, Polenta, G, Reinecke, M, Remazeilles, M, Renzi, A, Rocha, G, Rosset, C, Rubiño-Martín, J A, Ruiz-Granados, B, Salvati, L, Sandri, M, Scott, D, Shellard, E P S, Spencer, L D, Sunyaev, R, Tauber, J A, Toffolatti, L, Valenziano, L, Vielva, P, Villa, F, Wandelt, B D, White, M, White, S D M, Zacchei, A
• Format: Article
• Language: English
• Subjects: Amplitudes; Astronomical models; Cosmology; Dark matter; Density; Hubble constant; Neutrinos; Parameters; Universe; Variation
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1807.06209

We present cosmological parameter results from the final full-mission Planck measurements of the CMB anisotropies. We find good consistency with the standard spatially-flat 6-parameter \(\Lambda\)CDM cosmology having a power-law spectrum of adiabatic scalar perturbations (denoted "base \(\Lambda\)CDM" in this paper), from polarization, temperature, and lensing, separately and in combination. A combined analysis gives dark matter density \(\Omega_c h^2 = 0.120\pm 0.001\), baryon density \(\Omega_b h^2 = 0.0224\pm 0.0001\), scalar spectral index \(n_s = 0.965\pm 0.004\), and optical depth \(\tau = 0.054\pm 0.007\) (in this abstract we quote \(68\,\%\) confidence regions on measured parameters and \(95\,\%\) on upper limits). The angular acoustic scale is measured to \(0.03\,\%\) precision, with \(100\theta_*=1.0411\pm 0.0003\). These results are only weakly dependent on the cosmological model and remain stable, with somewhat increased errors, in many commonly considered extensions. Assuming the base-\(\Lambda\)CDM cosmology, the inferred late-Universe parameters are: Hubble constant \(H_0 = (67.4\pm 0.5)\)km/s/Mpc; matter density parameter \(\Omega_m = 0.315\pm 0.007\); and matter fluctuation amplitude \(\sigma_8 = 0.811\pm 0.006\). We find no compelling evidence for extensions to the base-\(\Lambda\)CDM model. Combining with BAO we constrain the effective extra relativistic degrees of freedom to be \(N_{\rm eff} = 2.99\pm 0.17\), and the neutrino mass is tightly constrained to \(\sum m_\nu< 0.12\)eV. The CMB spectra continue to prefer higher lensing amplitudes than predicted in base -\(\Lambda\)CDM at over \(2\,\sigma\), which pulls some parameters that affect the lensing amplitude away from the base-\(\Lambda\)CDM model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) BAO data. (Abridged)