The Non-Uniform Distribution of Galaxies from Data of the SDSS DR7 Survey

TL;DR

This study analyzes SDSS DR7 galaxy data, revealing non-uniform, fractal-like distribution patterns up to hundreds of megaparsecs, challenging the assumption of large-scale homogeneity.

Contribution

It provides a detailed analysis of galaxy distribution using multiple methods, demonstrating persistent inhomogeneities and fractal behavior at large scales.

Findings

Conditional density follows a power-law with fractal dimension D ≈ 2.2 up to 30 Mpc/h.

Distribution remains inhomogeneous with density contrast up to 200 Mpc/h.

Translation invariance is violated up to 300 Mpc/h.

Abstract

We have analyzed the spatial distribution of galaxies from the release of the Sloan Digital Sky Survey of galactic redshifts (SDSS DR7), applying the complete correlation function (conditional density), two-point conditional density (cylinder), and radial density methods. Our analysis demonstrates that the conditional density has a power-law form for scales lengths 0.5-30 Mpc/h, with the power-law corresponding to the fractal dimension D = 2.2+-0.2; for scale lengths in excess of 30 Mpc/h, it enters an essentially flat regime, as is expected for a uniform distribution of galaxies. However, in the analysis applying the cylinder method, the power-law character with D = 2.0+-0.3 persists to scale lengths of 70 Mpc/h. The radial density method reveals inhomogeneities in the spatial distribution of galaxies on scales of 200 Mpc/h with a density contrast of two, confirming that translation invariance is violated in the distribution of galaxies to 300 Mpc/h, with the sampling depth of the SDSS galaxies being 600 Mpc/h.