Speaker
Description
Unexpected anomalies have been identified in the WMAP and Planck cosmic microwave background (CMB) temperature data, showing a mild tension with the remarkably successful ΛCDM model. However, their statistical significance is not sufficient to distinguish between a genuine departure from ΛCDM and the possibility of observing a rare realisation of the CMB, where those anomalies are merely statistical flukes. Unfortunately, the latter scenario, referred to as the “fluke hypothesis”, cannot be tested in depth withouth new information, such as that provided by CMB polarisation.
In this talk, I will present our recent forecast testing the fluke hypothesis using the E-mode CMB polarisation signal as it might be observed by the LiteBIRD satellite. In order to do this, we constructed two datasets. The first consists of unconstrained realisations of the ΛCDM model, while the second one is generated by constraining the E-mode component that is correlated with temperature to the inpainted Planck 2018 SMICA temperature map. We then applied a set of statistical estimators, historically used to test these anomalies, to both datasets and compared their outcomes. We find that only tests based on cross-statistical measures from temperature and E-modes allow the rejection of the fluke hypothesis with a moderate level of confidence.
