Скачать или смотреть Matteo Billi - The CMB lack of power anomaly with the latest Planck data

Abstract: "The so-called CMB anomalies are unexpected features observed at large angular scales in the CMB temperature maps, as observed by the COBE, WMAP and Planck satellites, that deviate from the cosmological model ΛCDM with a statistical significance typically around 2-3 sigma C.L.. These anomalies are not all independent and a certain degree of correlation exists.
In this talk we focus on the lack of power anomaly which consists in a missing of power with respect to what foreseen by ΛCDM model. This anomaly might hint at a new cosmological phase before the standard inflationary era, for example an early fast-roll phase of the inflaton could naturally explain such a lack of power. This effect has been studied with WMAP data and with Planck 2013, 2015 and 2018 data, measuring a lower-tail-probability (LTP) of the order of a few per cent. However, with only the observations based on the CMB temperature map the statistical significance is currently not strong enough to support the existence of new physics beyond the standard cosmological model.
Here we investigate how CMB polarisation data improve the understanding of this feature. To this end, we apply to the last Planck data, both PR3 (2018) and PR4 (2020) releases, a new class of estimators able to evaluate this anomaly considering temperature and polarisation data both separately and in a jointly way. This is the first time that the PR4 dataset is used to study this anomaly. In order to critically evaluate this feature, and taking into account the residuals of known systematic effects present in the Planck datasets, we analyse the foreground-cleaned CMB maps using different combinations of sky masks, harmonic range and binning on the CMB multipoles. Our analysis shows that the estimator based only on temperature data confirms the presence of a lack of power with a lower-tail-probability (LTP) less than or equal to 0.33% and equal to 1.16%, for PR3 and PR4 respectively. To our knowledge the LTP less than or equal to 0.33% for the PR3 dataset is the lowest one present in the literature considering the Planck confidence mask. We find significant differences between these two datasets when just polarisation is taken into account. However, we also show that for the PR3 dataset the inclusion of the subdominant polarisation information provides estimates which are less likely accepted in a ΛCDM cosmological model than the only-temperature analysis on the whole harmonic-range considered."