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Large Scale Structure of the Universe
Galaxies are not uniformly distributed in space. On large scales the Universe
displays coherent structure, with galaxies residing in groups and clusters on
scales of ~1-3 Mpc/h, which lie at the intersections of long filaments of
galaxies that are >10 Mpc/h in length. Vast regions of relatively empty space,
known as voids, contain very few galaxies and span the volume in between these
structures. This observed large scale structure depends both on cosmological
parameters and on the formation and evolution of galaxies. Using the two-point
correlation function, one can trace the dependence of large scale structure on
galaxy properties such as luminosity, color, stellar mass, and track its
evolution with redshift. Comparison of the observed galaxy clustering
signatures with dark matter simulations allows one to model and understand the
clustering of galaxies and their formation and evolution within their parent
dark matter halos. Clustering measurements can determine the parent dark matter
halo mass of a given galaxy population, connect observed galaxy populations at
different epochs, and constrain cosmological parameters and galaxy evolution
models. This chapter describes the methods used to measure the two-point
correlation function in both redshift and real space, presents the current
results of how the clustering amplitude depends on various galaxy properties,
and discusses quantitative measurements of the structures of voids and
filaments. The interpretation of these results with current theoretical models
is also presented.Comment: Invited contribution to be published in Vol. 8 of book "Planets,
Stars, and Stellar Systems", Springer, series editor T. D. Oswalt, volume
editor W. C. Keel, v2 includes additional references, updated to match
published versio
Large Scale Structure of the Universe: Current Problems
The mean power spectrum of galaxies is compared with theoretical models.
Possibilities to explain the observed power spectrum are discussed.
Superclusters and voids form a quasi-regular lattice of mean cell size 120 Mpc;
the main axis of the lattice is directed toward the supergalactic Y coordinate.
Principal conclusions are that on scales around 100 Mpc the Universe is neither
homogeneous nor isotropic and that some of the presently accepted cosmological
paradigms need revision if the available observational data represent a fair
sample of the Universe.Comment: 10 pages LaTeX text (sty files added), 6 PostScript Figures,
submitted to Proceedings of the Meeting "The Chaotic Universe", ed.
V.G.Gurzadyan and R.Ruffini, World Scientific, Singapor
Dark Energy and Large-Scale Structure of the Universe
The evolution of matter density perturbations in two-component model of the
Universe consisting of dark energy (DE) and dust-like matter (M) is considered.
We have analyzed it for two kinds of DE with : a) unperturbed
energy density and b) perturbed one (uncoupled with matter). For these cases
the linear equations for evolution of the gauge-invariant amplitudes of matter
density perturbations are presented. It is shown that in the case of
unperturbed energy density of DE the amplitude of matter density perturbations
grow slightly faster than in the second case.Comment: 4 pages, 1 figure, submitted to the proceedings of international
conference "Astronomy in Ukraine - Past, Present, Future", July 15-17, Kiev,
Ukrain
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