Complexity in cosmic structures
arXiv:astro-ph/0401204 · doi:10.1016/j.physa.2004.02.022
Abstract
We discuss correlation properties of a general mass density field introducing a classification of structures based on their complexity. Standard cosmological models for primordial mass fluctuations are characterized by a sort of large-scale stochastic order, that we call super-homogeneity to highlight the fact that mass fluctuations increase as a function of scale in the slowest possible way for any stochastic mass field. On the other hand the galaxy spatial distribution show complex structures with a high degree of inhomogeneity and fractal-like spatial correlations up to some relevant cosmological scale. The theoretical problem of cosmological structure formation should then explain the growth of strongly correlated and non-linear structures from the very uniform field of density fluctuations given as standard initial condition.
6 pages 5 postscript figures. To be published in the proceedings of the Conference "A non-linear worlds: the real world" Second international conference on Frontier science, (08-12.09.2003, Pavia Italy)