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Determination of the cosmological parameters in the framework of the Friedmann-Lemaître model

Dyaa Chbib 1, 2
2 CPT - E3 Cosmologie
CPT - Centre de Physique Théorique - UMR 7332
Abstract : A century after the Universe model of Friedmann-Lemaître, the observations comfort it with a cosmological constant Λ and a dark matter component without pressure (dust) and cold dominating the baryonic one, which is denoted by ΛCDM model or standard model. The acceleration of the expansion of the Universe confirmed by the Hubble diagram of the supernovae in 1998 imposes a strictly positive value on the cosmological constant. My thesis work focuses on the estimation of the cosmological parameters values of the standard model using the null correlation technique. This approach has the advantage of being more robust than the usual techniques. In particular, it is not necessary to specify the luminosity function, it is derived from the data analysis. In addition, it accounts for the Malmquist bias due to selection effects on apparent magnitude. This work deals with modelling samples of the quasar event and the supernova event, which enables us to generate samples in order to validate the statistical approaches. We used data from the Sloan Digital Sky Survey (SDSS) for quasars, and the SuperNova Legacy Survey (SNLS) and SDSS-II for supernovae. The Statistical inferences suggest a Universe spatially Closed and a weaker presence of dark matter than that in the Standard model. Such a statistical analysis can be used to constrain dark energy models. Application of this technique might be useful for analyzing of clusters of galaxies observed through the effect of Sunyaev Zel'dovich, in view of deriving the cosmological model and provide an answer to the question of the contribution of massive neutrinos in the formation of clusters in the primordial era of the Universe.
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Submitted on : Monday, July 30, 2018 - 1:41:33 PM
Last modification on : Wednesday, November 3, 2021 - 9:52:35 AM
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Dyaa Chbib. Determination of the cosmological parameters in the framework of the Friedmann-Lemaître model. Physics [physics]. AIX-MARSEILLE UNIVERSITÉ, FACULTÉ DES SCIENCES -LUMINY CENTRE DE PHYSIQUE THÉORIQUE-UMR 7332, 2017. English. ⟨tel-01851540⟩



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