Testing a specific implementation of the Alcock-Paczyński test on the Magneticum simulations

In cosmology, accurately determining the parameters of a given model is essential for properly inferring the evolution of the universe and explaining its observable characteristics. The ΛCDM (Λ-cold dark matter) model, widely considered in cosmology, predicts the existence of three fundamental components: matter (comprising both dark and baryonic matter), radiation, and the cosmological constant (Λ). Each of these components contributes to the total density of the universe. To quantify these contributions, we usually use density parameters. In this thesis, our aim has been to test the efficiency of a particular method for determining the matter density parameter, called the Alcock-Paczyński (AP) test. We took advantage of the geometric anisotropies inherent in the two-point correlation function of different simulated cosmic tracers, which emerged from the assumption of a wrong cosmology when calculating the comoving distances. We employed a particular method to conduct the AP test while modeling the anisotropic distortions involving a Boltzmann solver.