2005/07/12 by Francesco Sylos Labini, Labini, Francesco Sylos
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0507277
8 pages, 6 .eps figures
arxiv created 2005/07/12 · openalex publication_date 2005/07/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
One of the main problems in the studies of large scale galaxy structures concerns the relation of the correlation properties of a certain population of objects with those of a selected subsample of it, when the selection is performed by considering physical quantities like luminosity or mass. I consider the case where the sampling is defined as in the simplest thresholding selection scheme of the peaks of a Gaussian random field as well as the case of the extraction of point distributions in high density regions from gravitational N-body simulations. I show that an invariant scale under sampling is represented by the zero-crossing scale of ξ(r). By considering recent measurements in the 2dF and SDSS galaxy surveys I note that the zero-point crossing length has not yet been clearly identified, while a dependence on the finite sample size related to the integral constraint is manifest. I show that this implies that other length scales derived from ξ(r) are also affected by finite size effects. I discuss the theoretical implications of these results, when considering the comparison of structures formed in N-body simulations and observed in galaxy samples, and different tests to study this problem.