AN UPPER LIMIT TO THE DENSITY INHOMOGENEITY IN THE UNIVERSE

1986 ◽  
Vol 01 (02) ◽  
pp. 87-93 ◽  
Author(s):  
LI-ZHI FANG ◽  
YAO-QUAN CHU ◽  
XING-FEN ZHU
Keyword(s):  
Gravitational Lensing ◽  
Density Fluctuation ◽  
Large Scale ◽  
Density Inhomogeneity ◽  
Large Scale Structures ◽  
Upper Limit ◽  
Luminous Matter ◽  
Scale Structures ◽  
Lensing Effect ◽  
The Universe

An upper limit to the amplitude of the overall density fluctuation has been found by means of the gravitational lensing effect of the density inhomogeneity on luminosities of quasars with larger redshifts. The observed differences of luminosities of quasars located at different directions are partially given by the lensing effect; therefore, a useful upper limit to the inhomogeneity can be derived if the luminosity distribution of quasars is uniform enough. We obtain this for the case of Ω=1 universe. The overall matter seems to be less clustered than the luminous matter by a factor of three. It may not be favoured for the biased dark matter scenario for the formation of large scale structures, in the universe.

scholarly journals Luminosity Inhomogeneity of Quasars and the Upper Limit of the Density Fluctuation in the Universe

1990 ◽  
Vol 139 ◽  
pp. 418-419
Author(s):  
Yaoquan Chu ◽  
Lizhi Fang
Keyword(s):  
Gravitational Lensing ◽  
Density Fluctuation ◽  
Density Inhomogeneity ◽  
Upper Limit ◽  
Lensing Effect ◽  
The Universe

An upper limit to the amplitude of the overall density fluctuation has been found by means of the gravitational lensing effect of the density inhomogeneity on luminosity of quasars with large redshifts. The observed differences of luminosities of quasars located at different directions are partially given by the lensing effect; therefore, a useful upper limit to the inhomogeneity can be derived.

scholarly journals Large-scale structure probes of modified gravity

2018 ◽  
Vol 27 (15) ◽  
pp. 1848005 ◽  
Author(s):  
Catherine Heymans ◽  
Gong-Bo Zhao
Keyword(s):  
Gravitational Lensing ◽  
Modified Gravity ◽  
Large Scale ◽  
Information Gain ◽  
Einstein Gravity ◽  
Large Scale Structures ◽  
Modified Gravity Theories ◽  
Scale Structures ◽  
The Impact ◽  
The Universe

Observations of the evolution of large-scale structures in the Universe provides unique tools to confront Einstein’s theory of General Relativity on cosmological scales. We review weak gravitational lensing and galaxy clustering studies, discussing how these can be used in combination in order to constrain a range of different modified gravity theories. We argue that in order to maximise the future information gain from these probes, theoretical effort will be required in order to model the impact of beyond-Einstein gravity in the nonlinear regime of structure formation.

QUASAR CLUSTERING AND ITS COSMOLOGICAL IMPLICATION

1989 ◽  
Vol 04 (14) ◽  
pp. 3477-3502 ◽  
Author(s):  
LI ZHI FANG
Keyword(s):  
Structure Formation ◽  
Absorption Line ◽  
Large Scale ◽  
Total Density ◽  
Density Inhomogeneity ◽  
Large Scale Structures ◽  
Cosmological Implication ◽  
Galaxy Distribution ◽  
Scale Structures ◽  
The Universe

The clusterings of quasars and absorption line clouds have been analyzed from the viewpoint of the structure formation of the universe. It was found that the features of quasar clustering are quite different from those of galaxies. These results have already given several meaningful constraints on the structure formation, as follows: (a) quasar clustering is much weaker than in galaxies; (b) large scale structures, such as superclusters, should probably be formed after the epoch z~2; (c) the amplitude of the total density inhomogeneity seems to be less than that of galaxy distribution by at least a factor of 3–5 (in a Ω=1 universe); (d) Ly-α absorption clouds may be formed by different processes of clustering from that of glaxies.

scholarly journals Large-Scale Structure in the Universe: Spatial Distribution and Peculiar Velocities

1987 ◽  
Vol 124 ◽  
pp. 335-348
Author(s):  
Neta A. Bahcall
Keyword(s):  
Dark Matter ◽  
Spatial Distribution ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Clusters Of Galaxies ◽  
Large Scale Structures ◽  
Peculiar Velocities ◽  
Scale Structures ◽  
The Universe

The evidence for the existence of very large scale structures, ∼ 100h−1Mpc in size, as derived from the spatial distribution of clusters of galaxies is summarized. Detection of a ∼ 2000 kms−1 elongation in the redshift direction in the distribution of the clusters is also described. Possible causes of the effect are peculiar velocities of clusters on scales of 10–100h−1Mpc and geometrical elongation of superclusters. If the effect is entirely due to the peculiar velocities of clusters, then superclusters have masses of order 1016.5M⊙ and may contain a larger amount of dark matter than previously anticipated.

scholarly journals Association Of Distant Radio Sources And Foreground Galaxies

1996 ◽  
Vol 173 ◽  
pp. 83-88
Author(s):  
E. Martínez-González ◽  
N. Benítez
Keyword(s):  
Gravitational Lensing ◽  
Large Scale ◽  
Radio Sources ◽  
Weak Gravitational Lensing ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Red Galaxies ◽  
Intermediate Redshifts

A statistically significant (99.1%) excess of red galaxies from the APM Sky Catalogue is found around a sample of z ∼ 1 1Jy radio sources. The most plausible explanation for this result seems to be the magnification bias caused by the weak gravitational lensing of large scale structures at intermediate redshifts.

Two types of voids and super-large scale structures in the universe?

1994 ◽  
Vol 5 (1-4) ◽  
pp. 75-79 ◽  
Author(s):  
S. A. Pustil'nik ◽  
A. V. Ugryumov ◽  
V. A. Lipovetsky
Keyword(s):  
Large Scale ◽  
Large Scale Structures ◽  
Scale Structures ◽  
The Universe
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