Light-cone effects in the galaxy 2-point function

Diplôme Thèse Light-cone effects in the galaxy 2-point function eng 2018-10-12 author Tansella Vittorio 782021 director Durrer Ruth 0000-0001-9833-2086 106998 10.13097/archive-ouverte/unige:109997 urn:nbn:ch:unige-1099976 Sc. 5267 This thesis investigates one of the most important observables in cosmology: the galaxy two- point function. The proper characterisation of this quantity is of the utmost importance if we want to compare theoretical predictions with the experimental results coming from planned redshift surveys. In particular we focus here on the modification that light-cone effects in- troduce – at large scales – in the correlation function. We start by computing, through first-order cosmological perturbation theory, expressions describing the galaxy distribution in the universe, i.e. galaxy number counts. These results are then used in order to construct the fully relativistic correlation function, which is valid in full-sky, i.e. beyond the so-called flat-sky approximation. A publicly available code is provided for fast and accurate numerical evaluation of the two-point function which allows us to forecast the possibility, with future or planned experiments, of constraining cosmological parameters through the multipoles decom- position of the correlation function. Other relevant topics, related to the two-point function, that we discuss in this work are: the regularisation of an apparent infra-red divergence in the potentials terms such as the Sachs-Wolfe effect, the existence of a second feature in the matter correlation function due to the baryon-baryon correlation in the early universe and, finally, a framework to analyse a possible anisotropic component in the two-point function. Cosmology Galaxies Dewey 500.2 37 Département de physique théorique 133 false 8a8c9725-4db9-41f9-a5a2-df0b06b95dd8 Thesis Public thesis_A.pdf 10034402 application/pdf openAccess Faculté des sciences / Section de physique / Département de physique théorique

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Tansella, Vittorio