On the consistency of ΛCDM with CMB measurements in light of the latest Planck, ACT and SPT data

Abstract

AbstractUsing Gaussian Processes we perform a thorough, non-parametric consistency test of the ΛCDM model when confronted with state-of-the-art TT, TE, and EE measurements of the anisotropies in the Cosmic Microwave Background by thePlanck, ACT, and SPT collaborations. Using ΛCDM's best-fit predictions to the TTTEEE data fromPlanck, we find no statistically significant deviations when looking for signatures in the residuals across the different datasets. The results of SPT are in good agreement with the ΛCDM best-fit predictions to thePlanckdata, while the results of ACT are only marginally consistent. However, when using the best-fit predictions to CamSpec — a recent reanalysis of thePlanckdata — as the mean function, we find larger discrepancies between the datasets. Our analysis also reveals an interesting feature in the polarisation (EE) measurements from the CamSpec analysis, which could be explained by a slight underestimation of the covariance matrix. Interestingly, the disagreement between CamSpec andPlanck/ACT is mainly visible in the residuals of the TT spectrum, the latter favoring a scale-invariant tiltns≃ 1, which is consistent with previous findings from parametric analyses. We also report some features in the EE measurements captured both by ACT and SPT which are independent of the chosen mean function and could be hinting towards a common physical origin. For completeness, we repeat our analysis using the best-fit spectra to ACT+WMAP as the mean function. Finally, we test the internal consistency of thePlanckdata alone by studying the high and low-ℓ ranges separately, finding no discrepancy between small and large angular scales.