Testing the Copernican and Cosmological Principles in the local universe with galaxy surveys

Abstract

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

12 pages, 3 figures, accepted for publication in JCAP

References in corpus (13)

• A general test of the Copernican Principle
• Exact solution to the averaging problem in cosmology
• Accelerated expansion from structure formation
• A Test of the Copernican Principle
• Living in a Void: Testing the Copernican Principle with Distant Supernovae
• Mimicking Dark Energy with Lemaitre-Tolman-Bondi Models: Weak Central Singularities and Critical Points
• Average observational quantities in the timescape cosmology
• Archipelagian Cosmology: Dynamics and Observables in a Universe with Discretized Matter Content
• Breaking the self-averaging properties of spatial galaxy fluctuations in the Sloan Digital Sky Survey - Data Release Six
• Galaxy distribution and extreme value statistics
• Energy conditions bounds and their confrontation with supernovae data
• Gravitational energy and cosmic acceleration
• Persistent fluctuations in the distribution of galaxies from the Two degree Field Galaxy Redshift Survey

Cited by in corpus (14)

• Establishing homogeneity of the universe in the shadow of dark energy
• Testing the Copernican principle by constraining spatial homogeneity
• Toward physical cosmology: focus on inhomogeneous geometry and its non-perturbative effects
• A Robust Measure of Cosmic Structure beyond the Power-Spectrum: Cosmic Filaments and the Temperature of Dark Matter
• Testing the Cosmic Anisotropy with Supernovae Data: Hemisphere Comparison and Dipole Fitting
• Age Problem in Lemaitre-Tolman-Bondi Void Models
• Probing cosmic isotropy in the Local Universe
• Probing large scale homogeneity and periodicity in the LRG distribution using Shannon entropy
• CMASS galaxy sample and the ontological status of the cosmological principle
• Spatial density fluctuations and selection effects in galaxy redshift surveys
• Complementary consistency test of the Copernican principle via Noether's theorem and machine learning forecasts
• THESEUS$-$BTA cosmological tests using Multimessenger Gamma-Ray Bursts observations
• Statistics of the Planck CMB signal in direction of gamma-ray bursts from the BATSE and BeppoSAX catalogs
• Multi-fluid Theory and Cosmology: A Convective Variational Approach to Interacting Dark-Sector