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Modélisation Bayésienne des mesures de vitesses particulières dans le projet CosmicFlows

Abstract : The cosmological concordance model relies on the existence of a ≪ dark ≫ matter which hypothetically only interacts through gravity. Hence, the dark matter could not be observed directly with standard techniques. Since they directly probe gravity, peculiar velocities of galaxies are an unbiased tool to probe the matter content of the Universe. They can trace the total matter field and constrain the Local Universe’s expansion rate and growth of structures. The peculiar velocity of a galaxy can only be measured from its distance, which determination is very inaccurate for distant objects. If not correctly modeled, these uncertainties can lead to biaised analyses and poor constraints on the ΛCDM model. Within this context, this PhD studies the systematic and statistical errors of peculiar velocity analyses. First by investigating and modeling these errors. Then by building Bayesian models to include them. In particular, a model of the Local Universe’s velocity field from the observations of the rotational velocity of galaxies is presented. This model relies on the ΛCDM’s peculiar velocity correlations and on a Tully-Fisher relation model. The model has then been applied to the CosmicFlows-3 catalog of distances and provides a new kinematic map of the Local Universe
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Submitted on : Monday, March 18, 2019 - 1:23:15 PM
Last modification on : Friday, October 23, 2020 - 4:45:14 PM


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  • HAL Id : tel-02068966, version 2



Romain Graziani. Modélisation Bayésienne des mesures de vitesses particulières dans le projet CosmicFlows. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université de Lyon, 2018. Français. ⟨NNT : 2018LYSE1143⟩. ⟨tel-02068966v2⟩



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