Planck 2018 results. VIII. Gravitational lensing

Abstract

We present measurements of the cosmic microwave background (CMB) lensing potential using the final $\text{Planck}$ 2018 temperature and polarization data. We increase the significance of the detection of lensing in the polarization maps from $5\ddot{I}ƒ$ to $9\ddot{I}ƒ$. Combined with temperature, lensing is detected at $40\ddot{I}ƒ$. We present an extensive set of tests of the robustness of the lensing-potential power spectrum, and construct a minimum-variance estimator likelihood over lensing multipoles $8\le L\le 400$. We find good consistency between lensing constraints and the results from the $\text{Planck}$ CMB power spectra within the $\hat{\mathrm{I}}›\mathrm{CDM}$ model. Combined with baryon density and other weak priors, the lensing analysis alone constrains $\ddot{I}{ƒ}_8\hat{I}{\text{c◯}}_{\mathrm{m}}^{0.25}=0.589\pm 0.020$ ($1\ddot{I}ƒ$ errors). Also combining with baryon acoustic oscillation (BAO) data, we find tight individual parameter constraints, $\ddot{I}{ƒ}_8=0.811\pm 0.019$, $H_0=67.9_{-1.3}^{+1.2}\text{km}{\text{s}}^{-1}{\mathrm{Mpc}}^{-1}$, and $\hat{I}{\text{c◯}}_{\mathrm{m}}=0.303_{-0.018}^{+0.016}$. Combining with $\text{Planck}$ CMB power spectrum data, we measure $\ddot{I}{ƒ}_8$ to better than $1\%$ precision, finding $\ddot{I}{ƒ}_8=0.811\pm 0.006$. We find consistency with the lensing results from the Dark Energy Survey, and give combined lensing-only parameter constraints that are tighter than joint results using galaxy clustering. Using $\text{Planck}$ cosmic infrared background (CIB) maps we make a combined estimate of the lensing potential over $60\%$ of the sky with considerably more small-scale signal. We demonstrate delensing of the $\text{Planck}$ power spectra, detecting a maximum removal of $40\%$ of the lensing-induced power in all spectra. The improvement in the sharpening of the acoustic peaks by including both CIB and the quadratic lensing reconstruction is detected at high significance (abridged).

Abstract abridged for arxiv submission. Lensing data products available at https://wiki.cosmos.esa.int/planck-legacy-archive/index.php/Lensing. Matches version accepted by A&A, with minor updates from v1