Kinematic effects and the break of statistical isotropy of the cosmic microwave background fluctuations

• Ano de defesa: 2021
• Autor(a) principal: Mogollón, Esteban Ricardo Chalbaud
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Cosmic Microwave Background; cosmological observations; cosmological parameters.; observações cosmológicas; parâmetros cosmológicos.; Radiação cósmica de fundo
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/43/43134/tde-31052021-162009/

In this work, we study the impact of a non-comoving observer measuring the anisotropies of the Cosmic Microwave Background (CMB). We recover the cross-correlation signal appearing in neighboring multipoles, as a consequence of the statistical isotropy violation, caused by the observer\'s movement. It is also presented the impact of this effect over the temperature and polarization power spectra. We tested the impact of the statistical isotropy violation on cosmological parameters using three different likelihood estimators, which combine temperature and polarization measurements. These estimators were used to restrict a sub-set of cosmological parameters of the $\\Lambda$CDM model (more precisely, $\\Omega_{b}h^2$, $\\Omega_{c}h^2$, $100 \\Theta_{MC}, \\tau, \\ln(10^{10}A_{s})$, $n_{s}$) obtaining constraints on the parameters using CMB anisotropy measurements compatible with a \\textit{Planck}-like satellite. No significant systematic effects were found in this subset of $\\Lambda$CDM parameters induced by the kinematic effects of an observer with peculiar velocity $\\boldsymbol{\\beta} = 1.23 \\times 10^{-3}$, at least using full-sky CMB maps, in both temperature and polarization. Finally, we built a maximum likelihood estimator based on the combined effects of Doppler modulation and relativistic aberration. This estimator was applied to determine the peculiar velocity $\\boldsymbol{\\beta}$ using full-sky CMB synthetic maps as input data, as well as Bayesian analysis techniques using Markov chains for reconstructing the posterior probability distributions. During the consistency tests performed, we did not detect any significant bias in the estimator. On the other hand, its precision on the magnitude of peculiar velocity was estimated to be $84$ km s $^{-1}$ and an angular resolution of $11.5^{\\circ}$, comparable, therefore, to those obtained, via the quadratic estimator, by the \\textit{Planck} collaboration of $78$ km s$^{-1}$ and $14^{\\circ}$, respectively.