Séminaire Doctoral / Seminar PhD |
| « Present and future of cosmic microwave background data » |
|
Etienne Camphuis |
| The South Pole Telescope (SPT-3G) is a ground based experiment observing the cosmic microwave background (CMB) in both intensity and polarization, with unprecedented resolution and noise levels. It aims at putting constraints on cosmological parameters as tight as those of the Planck satellite. In this YMCA, I will introduce the physical background of likelihood analyses with CMB datasets, giving an overview of the actual challenges of CMB observation. After this introduction, I will present results on the pipeline we are building for SPT-3G. Firstly, accurate covariance matrices are required for a reliable estimation of cosmological parameters from pseudo-power spectrum estimators. We have evaluated the accuracy of the classical approximations used in the literature to derive analytical covariance matrices of pseudo-spectra and we propose a new approximation which improves over the old ones to reach a precision of 1%. Then, I will introduce an inpainting algorithm that we could use to cure spurious signal in our power spectrum estimator due to point sources. Our results are easily applicable to any other cosmological probe observing small patches of the sky. |
|
vendredi 28 janvier 2022 - 16:00 Salle du Conseil, Institut d'Astrophysique |
| Page web du séminaire / Seminar's webpage |