The choice of Planck CMB likelihood in cosmological analyses

Abstract

We compare cosmological parameters from different Planck sky maps and likelihood pipelines, assessing robustness of cosmological results with respect to the choice of the latest Planck maps-likelihood combination. We show that, for the Planck multipole range retained in combination with ground-based observations, different products give very similar cosmological solutions; small remaining differences are reduced by the addition of other CMB datasets to Planck. In particular, constraints on extended cosmological models benefit from the addition of small-scale power from ground-based experiments and are completely insensitive to the choice of Planck maps and likelihood. For this work we derive and release a nuisance-marginalized dataset and CamSpec-NPIPE-lite likelihood for the Planck NPIPE data injected into the CamSpec likelihood - which are usually used to obtain the reference Planck PR4 cosmology. Using the extracted CMB spectra we show that the additional constraining power for cosmology is coming from polarization at all scales and from temperature at multipoles above 1500 when going from PR3 to PR4. We also show that full marginalization over the CamSpec foreground nuisance parameters can impact parameter inference and model selections when truncating some scales; our new likelihood enables correct combinations with other CMB datasets.