Constraints on primordial non-Gaussianity from Planck PR4 data

¹ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
² Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
³ Université Paris Cité, CNRS, Astroparticule et Cosmologie, 75013 Paris, France

^⋆ Corresponding author: gabriel.jung@protonmail.com

Received: 24 April 2025
Accepted: 21 August 2025

Abstract

We performed the first bispectrum analysis of the final Planck release temperature and E-polarization cosmic microwave background data, called PR4. We used the binned bispectrum estimator pipeline that was also used for the previous Planck releases as well as the integrated bispectrum estimator. We tested the standard primordial (local, equilateral, and orthogonal) and secondary (lensing, unclustered point sources, and cosmic infrared background) bispectrum shapes. The final primordial results of the full T + E analysis are f_NL^local = −0.1 ± 5.0, f_NL^equil = 6 ± 46, and f_NL^ortho = −8 ± 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 performed several validation tests and found 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.