Towards cosmological parameters with the SPT-3G 19/20 cosmic microwave background data

• Main Author: Camphuis, Etienne
• Other Authors: Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Karim Benabed, Silvia Galli, Eric Hivon
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2023
• Subjects: CMB; Cosmologie; Hubble constant; Data analysis; South Pole Telescope; Analyse de données; Télescope du Pôle Sud; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; Hubble; South Pole; South pole
• Online Access: https://theses.hal.science/tel-04347707; https://theses.hal.science/tel-04347707/document; https://theses.hal.science/tel-04347707/file/CAMPHUIS_Etienne_these_2023.pdf

Observations of primary anisotropies in the cosmic microwave background (CMB) represent a crucial milestone in modern cosmology, offering a unique window into the physics of the early Universe. However, tensions in measurements compared to other probes, such as the Hubble tension, have emerged suggesting potential dis- crepancies within the cosmological concordance. Although these discrepancies may be attributed to systematic effects or statistical fluctuations, the consistent disparity between early and late Universe measurements might hint at new physics. Additionally, the temperature anisotropy measurements have not reached yet the cosmic variance limit at high multipoles, while the polarized anisotropies hold substantial untapped cosmological infor- mation. In this context, investigating a complementary range of multipoles and exploring polarization become vital avenues for potentially uncovering fundamental physics. The South Pole Telescope third-generation (SPT-3G) experiment is undertaking precisely this endeavor, aim- ing to provide state-of-the-art observations that enhance our understanding of the Universe. The objective of this thesis is to present a detailed analysis of the SPT-3G 2019-2020 primary anisotropies data. This dataset achieves a low noise level of 5μK-arcmin in temperature at 150GHz, making it cosmic variance limited for almost all the power spectrum multipole range. Forecasted constraints on cosmological parameters are comparable to the reference Planck experiment but from an independent and complementary dataset. Combining these con- straints is expected to yield at least twice the statistical power, and further improvements can be achieved by incorporating information from extended fields, lensing measurements, and other CMB datasets such as those from the Atacama Cosmology Telescope. To ensure the accuracy and precision of the analysis, the pipeline requires additional development. This thesis includes an in-depth study of the map-making pipeline and power spectrum estimation, along ...