Constraints on primordial non-Gaussianity from Planck PR4 data

Abstract: We perform the first bispectrum analysis of the final Planck release temperature and E-polarization CMB data, called PR4. We use the binned bispectrum estimator pipeline that was also used for the previous Planck releases as well as the integrated bispectrum estimator. We test the standard primordial (local, equilateral and orthogonal) and secondary (lensing, unclustered point sources and CIB) bispectrum shapes. The final primordial results of the full T+E analysis are $f_\mathrm{NL}^\mathrm{local} = -0.1 \pm 5.0$, $f_\mathrm{NL}^\mathrm{equil} = 6 \pm 46$ and $f_\mathrm{NL}^\mathrm{ortho} = -8 \pm 21$. These results are consistent with previous Planck releases, but have slightly smaller error bars than in PR3, up to $12\%$ smaller for orthogonal. They represent the best Planck constraints on primordial non-Gaussianity. The lensing and point source bispectra are also detected, consistent with PR3. We perform several validation tests and find in particular that the 600 simulations, used to determine the linear correction term and the error bars, have a systematically low lensing bispectrum. We show however that this has no impact on our results.