Related papers: Angular Size in a Static Universe
The universe is found to have undergone several phases in which the gravitational constant had different behaviors. During some epochs the energy density of the universe remained constant and the universe remained static. In the radiation…
Measuring the evolution in the clustering of galaxies over a large redshift range is a challenging problem. For a two-dimensional galaxy catalog, however, we can measure the galaxy-galaxy angular correlation function which provides…
Solving null-geodesic equations, behavior of angular diameter distances is studied in inhomogeneous cosmological models, which are given by performing N-body simulations with the CDM spectrum. The distances depend on the separation angle of…
We discuss how different theoretical predictions for the variance $\sigma^2$ of the distribution of radio sources can be matched to measurements from the FIRST survey at different flux limits. The predictions are given by the integration of…
Galaxy redshift surveys have achieved significant progress over the last couple of decades. Those surveys tell us in the most straightforward way what our local universe looks like. While the galaxy distribution traces the bright side of…
Using the focusing equation, the equation for the cosmological angular diameter distance is derived, based on the ideas of Academician Ya.B. Zel'dovich, namely, that the distribution of matter at small angles is not homogeneous, and the…
We discuss the ``angular size - redshift'' relation for compact radio sources distributed over a wide range of redshifts 0.01 < z < 4.73. Our study is based on a sample of 330 5 GHz VLBI contour maps taken from the literature. Unlike…
Unification by orientation is a ubiquitous concept in the study of active galactic nuclei. A gold standard of the orientation paradigm is the hypothesis that radio galaxies and radio-loud quasars are intrinsically the same, but are observed…
Recent observations of high redshift Supernovae at lower than expected value of the Hubble constant, widely interpreted as an evidence for accelerating expansion of the Universe, could alternatively be explained assuming a hyperbolic…
We are now beginning to learn detailed information about cosmological parameters from the shapes of the matter and radiation power spectra, together with their relative normalization. As more high quality data are gathered from galaxy…
The Cosmic Microwave Background (CMB) anisotropy constrains the geometry of the Universe because the positions of the acoustic peaks of the angular power spectrum depend strongly on the curvature of underlying three-dimensional space. In…
A new method is proposed for directly measuring the expansion rate of the universe through very precise measurement of the fluence of extremely stable sources. The method is based on the definition of the luminosity distance and its change…
The Big Bang frame of work for cosmology is a theoretical construct based upon one possible interpretation of the Hubble observation of the red shift from distant galaxies. Almost all of the scientific experimental evidence has been…
Under the assumption that the gas mass fraction of galaxy clusters estimated out to an outer hydrostatic radius is constant, it is possible to constrain the cosmological parameters by using the angular diameter distance relation with…
The simplest theory describing large-scale redshift-space distortions (RSD), based on linear theory and distant galaxies, depends on the growth of cosmological structure, suggesting that strong tests of General Relativity can be constructed…
We discuss the problem of how to calculate the distance between two cosmological objects given their redshifts and angular separation on the sky. Although of a fundamental nature, this problem and its solution seem to lack a detailed…
In the past decade, observational cosmology has had one of the most exciting periods in the past century. The precision with which we have been able to measure cosmological parameters has increased tremendously, while at the same time, we…
A united approach of the large-scale structure of a closed universe and the local spherically symmetric gravitational field is given by supposing an appropriate boundary condition. The general feature of the model obtained are the…
Recent puzzling observations such as the $H_o$ tension, large-scale anisotropies, and massive disk galaxies at high redshifts have been challenging the standard cosmological model. While one possible explanation is that the standard model…
The James Webb Space Telescope (JWST), which has recently become operational, is capable of detecting objects at record-breaking redshifts, $z \gtrsim 15$. This is a crucial advance for observational cosmology, as at these redshifts the…