Absence of selfaveraging and of homogeneity in the largescale galaxy distribution
Abstract
The properties of the galaxy distribution at large scales are usually studied using statistics which are assumed to be selfaveraging inside a given sample. We present a new analysis able to quantitatively map galaxy largescale structures while testing for the stability of average statistical quantities in different sample regions. We find that the newest samples of the Sloan Digital Sky Survey provide unambiguous evidence that galaxy structures correspond to largeamplitude density fluctuations at all scales limited only by sample sizes. The twopoint correlations properties are selfaveraging up to approximately 30 Mpc/h and are characterized by a fractal dimension D=2.1±0.1. Then at all larger scales probed density fluctuations are too large in amplitude and too extended in space to be selfaveraging inside the considered volumes. These inhomogeneities are compatible with a continuation of fractal correlations but incompatible with: i) a homogeneity scale smaller than 100 Mpc/h, ii) predictions of standard theoretical models, iii) mock galaxy catalogs generated from cosmological Nbody simulations.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 May 2009
 DOI:
 10.1209/02955075/86/49001
 arXiv:
 arXiv:0805.1132
 Bibcode:
 2009EL.....8649001S
 Keywords:

 Astrophysics;
 Condensed Matter  Statistical Mechanics;
 General Relativity and Quantum Cosmology
 EPrint:
 6 pages with 4 figures. Some changes to match the accepted version. To be published in Europhysics Letters (May 2009)