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From cosmology to galaxy formation : what can we learn from the large-scale structure of the Universe ?

Abstract : This thesis by publication is devoted to the theoretical understanding of the large-scale structure of the Universe and its role in the context of cosmology and galaxy formation. The birth and evolution of galaxies occur within the large cosmic highways drawn by the cosmic web and the natural question which arises is whether galaxies retain a memory of the large-scale cosmic flows from which they emerge. To address this key question, we will first show that in cosmological simulations, the spin of galaxies and the direction of their host filament are correlated in a mass-dependent way. This signal will be shown to be qualitatively understood in the context of hierarchical structure formation. An analytic model which explicitly takes into account the anisotropy of the cosmic web will complement this qualitative understanding by reproducing the measured correlations. Those ideas are important to understand the evolution of galaxy morphology but also to understand the intrinsic alignments of galaxies that contaminate cosmological probes like cosmic shear experiments. We will in particular measure this contamination directly from a state-of-the-art hydrodynamical simulation. In a second part, we will address the question of how to efficiently use large-scale structure data to probe the cosmological model describing our Universe by measuring its topology and geometry and using perturbation theory in the weakly and even mildly non-linear regime. The major contribution of this work is to analytically study the effect of redshift space distortions and non-linear collapse of structures on the topology, geometry and statistics of the cosmic density field.
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Submitted on : Friday, January 29, 2016 - 1:09:22 PM
Last modification on : Tuesday, December 8, 2020 - 3:38:06 AM
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  • HAL Id : tel-01264538, version 1


Sandrine Codis-Decara. From cosmology to galaxy formation : what can we learn from the large-scale structure of the Universe ?. Astrophysics [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2015. English. ⟨NNT : 2015PA066343⟩. ⟨tel-01264538⟩



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