Testing the Copernican and Cosmological Principles in the local universe with galaxy surveys - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




Testing the Copernican and Cosmological Principles in the local universe with galaxy surveys - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: Cosmological density fields are assumed to be translational and rotationalinvariant, avoiding any special point or direction, thus satisfying theCopernican Principle. A spatially inhomogeneous matter distribution can becompatible with the Copernican Principle but not with the stronger version ofit, the Cosmological Principle which requires the additional hypothesis ofspatial homogeneity. We establish criteria for testing that a given densityfield, in a finite sample at low redshifts, is statistically and-or spatiallyhomogeneous. The basic question to be considered is whether a distribution is,at different spatial scales, self-averaging. This can be achieved by studyingthe probability density function of conditional fluctuations. We find thatgalaxy structures in the SDSS samples, the largest currently available, arespatially inhomogeneous but statistically homogeneous and isotropic up to ~ 100Mpc-h. Evidences for the breaking of self-averaging are found up to the largestscales probed by the SDSS data. The comparison between the results obtained involumes of different size allows us to unambiguously conclude that the lack ofelf-averaging is induced by finite-size effects due to long-range correlatedfluctuations. We finally discuss the relevance of these results from the pointof view of cosmological modeling.



Author: Francesco Sylos Labini, Yuri V. Baryshev

Source: https://arxiv.org/







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