Presentation Archive

Quantitative Comparisons of the Largest Structures of the Universe between Observations and the LCDM Model

Changbom Park

January 13, 2014

Abstract: We show that the size and richness of all the largest structures of the universe discovered so far are consistent with the LCDM cosmological model, which adopts a homogeneous and isotropic universe with Gaussian primordial fluctuations growing according to General Relativity. Using the SDSS Main Galaxy sample, we find that the Sloan Great Wall is one of the largest large-scale structures (LSS) when the threshold density for LSS identification is relatively high. For a quantitative comparison with the LCDM model we make a large cosmological N-body simulation (Horizon Run 2), and perform many mock SDSS surveys. We find that the statistical properties of the observed LSSs agree astonishingly well with those of the LSSs in the mock surveys. Our simulation indicates that a structure like the Sloan Great Wall is typically the largest one but expected to be frequently found in SDSS-like surveys. We make a similar analysis for the HectoMAP survey data, and find the LSSs are again consistent with LCDM . On the other hand, we confirm that the large quasar group reported by Clowes et al. (2013) from the SDSS survey is likely to be an object found by a mere chance.