Resumo:
The distribution of galaxies, provided by large astronomical surveys, makes possible detailed studies of the nature of the primordial density fluctuations and the process of structure formation in the universe. Among the many physical phenomena that can be explored from these surveys are the baryon acoustic oscillations. Baryon Acoustic Oscillations (BAO) arise due to the competing effects of radiation pressure and gravity in the early Universe. The BAO features can be determined from the two-point galaxy correlation function. However, in order to construct the correlation function using spatial separations between pairs of galaxies, a fiducial cosmology is necessary. On the other hand, an almost model-independent correlation function ω(θ) can be obtained considering angular separations along with the direct detection of the purely transversal BAO signal. Precise estimates of the transversal BAO signal obtained from ω(θ) can, therefore, be used to discriminate a large number of cosmological models. In the first part of this Thesis, we provide six new measurements of the angular BAO signal using the tenth data release from Sloan Digital Sky Survey (DR10). In the second part, we explore how future galaxy survey will improve the cosmological parameter estimation by mapping a large portion of the sky. In particular, we investigate forecasts from the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J- PAS), which will be the one of the largest galaxies surveys in the next years. Using the Fisher matrix approach, we derive and analise forecasts for the main cosmological parameters from the distribution of galaxies and quasars which will be mapped by J-PAS.
