Speaker
Description
I provide a review of the fractal properties of the cosmic web. Extreme views on fractal properties were expressed by Pietronero and Davis. To get an unbiased view on fractal properties I describe fractal function found from angular 2D and spatial 3D distributions of galaxies, using numerical simulations and SDSS samples of galaxies in a box of side length 512 Mpc/h. To measure the fractal dimension, I use the structure function 𝑔(𝑟) = 1 + 𝜉(𝑟), and its log-gradient. 𝛾(𝑟). The fractal dimension function, 𝐷(𝑟) = 3 + 𝛾(𝑟), of 3D samples characterizes the structure of halos on small separations, 𝑟 ≤ 4 Mpc/h, and the distribution of galaxies in filaments on larger separations. Fractal dimension functions of 2D samples depend on the thickness of samples, L. In SDSS and simulated Millennium galaxy samples the internal structure of halos is invisible. The analysis shows that both Pietronero and Davis views have correct as well as wrong properties.