Inhomogeneities in the universe

Francesco Sylos Labini (1, 2)

1 Enrico Fermi Center for Study and Research | Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi
2 Istituto dei Sistemi Complessi

Standard models of galaxy formation predict that matter distribution is statistically homogeneous and isotropic and characterized by (i) spatial homogeneity for r < 10 Mpc/h, (ii) small-amplitude structures of relatively limited size (i.e., r < 100) Mpc/h and (iii) anti-correlations for r > r c ≈ 150 Mpc/h (i.e., no structures of size larger than r c). Whether or not the observed galaxy distribution is interpreted to be compatible with these predictions depend on the a-priori assumptions encoded in the statistical methods employed to characterize the data and on the aposteriori hypotheses made to interpret the results. We present strategies to test the most common assumptions and we find evidences that, in the available samples, galaxy distribution is spatially inhomogeneous for r < 100 Mpc/h but statistically homogeneous and isotropic. We conclude that the observed inhomogeneities pose a fundamental challenge to the standard picture of cosmology but they also represent an important opportunity which may open new directions for many cosmological puzzles.

Mots clés: 98.65.-r; 98.65.Dx; 98.80.-k

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]

Francesco Sylos Labini. Inhomogeneities in the universe. Classical and Quantum Gravity, 2011, 28 (16), pp.164003. ⟨10.1088/0264-9381/28/16/164003⟩. ⟨hal-00724408⟩