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Investigating Cosmological Distances As A Function Of The Red Shift In The Szekeres Inhomogeneous Cosmological Models
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Book Synopsis Investigating Cosmological Distances as a Function of the Red-shift in the Szekeres Inhomogeneous Cosmological Models by : Anthony Chukwuemeka Nwankwo
Download or read book Investigating Cosmological Distances as a Function of the Red-shift in the Szekeres Inhomogeneous Cosmological Models written by Anthony Chukwuemeka Nwankwo and published by . This book was released on 2011 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interpretation of cosmological observations depends on the choice of a cosmological model. One must choose a cosmological model, calculate the observables in the chosen cosmological model and then confront the results of the calculations with the data. Cosmological observations are made on the past null cone, which involve observation of luminosities and red-shifts of astrophysical objects like distant supernovae in the universe. The physical characteristics of these observed objects such as the red-shift and the magnitudes are dependent on the space-time in which they travelled through to reach the observer, and thus choosing the correct model of the universe is of crucial importance in the interpretation of cosmological observations. The universe has been observed to be inhomogeneous on scales that can affect observed quantities such as area distance, luminosity distance and red-shift. Because of this, it is necessary to use cosmological models that can take into account the observed inhomogeneities to study the universe such as the Szekeres inhomogeneous models and computing observable quantities in the Szekeres model is a non-trivial problem, more specifically computing the area distance in general requires one to compute the partial derivatives of the null vector components.
Book Synopsis Investigating Inhomogeneous Szekeres Models and Their Applications to Precision Cosmology by : Austin Chandler Peel
Download or read book Investigating Inhomogeneous Szekeres Models and Their Applications to Precision Cosmology written by Austin Chandler Peel and published by . This book was released on 2015 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exact solutions of Einstein's field equations that can describe the evolution of complex structures in the universe provide complementary frameworks to standard perturbation theory in which to analyze cosmological and astrophysical phenomena. The flexibility and generality of the inhomogeneous and anisotropic Szekeres metric make it the best known exact solution to explore nonlinearities in the universe. We study applications of Szekeres models to precision cosmology, focusing on the influence of inhomogeneities in two primary contexts--the growth rate of cosmic structures and biases in distance determinations to remote sources. We first define and derive evolution equations for a Szekeres density contrast, which quantifies exact deviations from a smooth background cosmology. Solving these equations and comparing to the usual perturbative approach, we find that for models with the same matter content, the Szekeres growth rate is larger through the matter-dominated cosmic era. Including a cosmological constant, we consider exact global perturbations, as well as the evolution of a single extended structure surrounded by an almost homogeneous background. For the former, we use growth data to obtain a best fit Szekeres model and find that it can fit the data as well as the standard Lambda-Cold Dark Matter (LCDM) cosmological model but with different cosmological parameters. Next, to study effects of inhomogeneities on distance measures, we build an exact relativistic Swiss-cheese model of the universe, where a large number of non-symmetric and randomly placed Szekeres structures are embedded within a LCDM background. Solving the full relativistic propagation equations, light beams are traced through the model, where they traverse the inhomogeneous structures in a way that mimics the paths of real light beams in the universe. For beams crossing a single structure, their magnification or demagnification reflects primarily the net density encountered along the path. Despite nontrivial evolution and density distributions of the structures, the effect of tidal shearing on the beams remains small. Finally, we study source magnification probability distributions for various redshifts, finding a limitation of the models in that the distributions do not consistently resemble those of gravitational lensing analyses in cosmological simulations.
Book Synopsis The Redshift Controversy by : George B. Field
Download or read book The Redshift Controversy written by George B. Field and published by Addison Wesley Longman. This book was released on 1973 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Red-shift-magnitude Relation and Observational Data by : Windsor L. Sherman
Download or read book The Red-shift-magnitude Relation and Observational Data written by Windsor L. Sherman and published by . This book was released on 1969 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Red shift-magnitude relation for universe model and observational data.
Book Synopsis An Approximate Solution for Luminosity Distance in Zero-pressure Relativistic Model Universes that Have the U-property by : Windsor L. Sherman
Download or read book An Approximate Solution for Luminosity Distance in Zero-pressure Relativistic Model Universes that Have the U-property written by Windsor L. Sherman and published by . This book was released on 1965 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Cosmological Observables in the Quasi-spherical Szekeres Model by : Robert G. Buckley
Download or read book Cosmological Observables in the Quasi-spherical Szekeres Model written by Robert G. Buckley and published by . This book was released on 2014 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: The standard model of cosmology presents a homogeneous universe, and we interpret cosmological data through this framework. However, structure growth creates nonlinear inhomogeneities that may affect observations, and even larger structures may be hidden by our limited vantage point and small number of independent observations. As we determine the universe's parameters with increasing precision, the accuracy is contingent on our understanding of the effects of such structures. For instance, giant void models can explain some observations without dark energy. Because perturbation theory cannot adequately describe nonlinear inhomogeneities, exact solutions to the equations of general relativity are important for these questions. The most general known solution capable of describing inhomogeneous matter distributions is the Szekeres class of models. In this work, we study the quasi-spherical subclass of these models, using numerical simulations to calculate the inhomogeneities' effects on observations. We calculate the large-angle CMB in giant void models and compare with simpler, symmetric void models that have previously been found inadequate to matchobservations. We extend this by considering models with early-time inhomogeneities as well. Then, we study distance observations, including selection effects, in models which are homogeneous on scales around 100 Mpc--consistent with standard cosmology--but inhomogeneous on smaller scales. Finally, we consider photon polarizations, and show that they are not directly affected by inhomogeneities. Overall, we find that while Szekeres models have some advantages over simpler models, they are still seriously limited in their ability to alter our parameter estimation while remaining within the bounds of current observations.
Book Synopsis Mathematical Aspects of Paradoxes in Cosmology by : Michal Křížek
Download or read book Mathematical Aspects of Paradoxes in Cosmology written by Michal Křížek and published by Springer Nature. This book was released on 2023-07-05 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a mathematical and numerical analysis of many problems which lead to paradoxes in contemporary cosmology, in particular, the existence of dark matter and dark energy. It is shown that these hypothetical quantities arise from excessive extrapolations of simple mathematical models to the whole physical universe. Written in a completely different style to most books on General Relativity and cosmology, the important results take the form of mathematical theorems with precise assumptions and statements. All theorems are followed by a corresponding proof, or an exact reference to the proof. Some nonstandard topics are also covered, including violation of the causality principle in Newtonian mechanics, a critical mathematical and numerical analysis of Mercury's perihelion shift, inapplicability of Einstein's equations to the classical two-body problem due to computational complexity, non-uniqueness of the notion of universe, the topology of the universe, various descriptions of a hypersphere, regular tessellations of hyperbolic spaces, local Hubble expansion of the universe, neglected gravitational redshift in the detection of gravitational waves, and the possible distribution of mass inside a black hole. The book also dispels some myths appearing in the theory of relativity and in contemporary cosmology. For example, although the hidden assumption that Einstein's equations provide a good description of the evolution of the whole universe is considered to be obvious, it is just a null hypothesis which has not been verified by any experiment, and has only been postulated by excessive extrapolations of many orders of magnitude.
Download or read book Seeing Red written by Halton C. Arp and published by Apeiron. This book was released on 1998 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Does the Universe Really Expand? by : Borys Abramenko
Download or read book Does the Universe Really Expand? written by Borys Abramenko and published by . This book was released on 1981 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Testing the Boundaries of Standard Cosmological Models by : Antonio Enea Romano
Download or read book Testing the Boundaries of Standard Cosmological Models written by Antonio Enea Romano and published by . This book was released on 2007 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Papers On Curved Spaces and Cosmology by : Alexander A. Friedmann
Download or read book Papers On Curved Spaces and Cosmology written by Alexander A. Friedmann and published by Minkowski Institute Press. This book was released on 2014-01-30 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: If the talented Russian physicist Alexander Alexandrovich Friedmann had to be introduced with a single sentence, the most appropriate sentence would be the title of his biography translated from the Russian: Alexander A. Friedmann: The Man who Made the Universe Expand. Indeed, he was the first to realize in 1922 that Einstein's equations have solutions which describe not only a stationary Universe as Einstein initially believed, but also a non-stationary world. Friedmann won the debate with Einstein over the admissibility of such solutions, but his life was too short and he could not see the triumph of his views when the experimental evidence fully supported his predictions and demonstrated that the Universe was expanding. This book contains three papers by Friedmann - "On the Curvature of Space", "On the Possibility of a World with a Constant Negative Curvature of Space", and "On the Geometry of Curved Spaces". The third paper is a 28-page manuscript (dated 15 April 1922) which has not been published even in Russian. Unlike the existing two English translations of Friedmann's 1922 and 1924 papers (done from the German publications), now these papers are translated directly from the original Russian texts.
Book Synopsis Testing Flatness of the Universe with Probes of Cosmic Distances and Growth by : Michael J. Mortonson
Download or read book Testing Flatness of the Universe with Probes of Cosmic Distances and Growth written by Michael J. Mortonson and published by . This book was released on 2009 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: When using distance measurements to probe spatial curvature, the geometric degeneracy between curvature and dark energy in the distance--redshift relation typically requires either making strong assumptions about the dark energy evolution or sacrificing precision in a more model-independent approach. Measurements of the redshift evolution of the linear growth of perturbations can break the geometric degeneracy, providing curvature constraints that are both precise and model-independent. Future supernova, CMB, and cluster data have the potential to measure the curvature with an accuracy of sigma(O K) = 0.002, without specifying a particular dark energy phenomenology. In combination with distance measurements, the evolution of the growth function at low redshifts provides the strongest curvature constraint if the high-redshift universe is well approximated as being purely matter dominated. However, in the presence of early dark energy or massive neutrinos, the precision in curvature is reduced due to additional degeneracies, and precise normalization of the growth function relative to recombination is important for obtaining accurate constraints. Curvature limits from distances and growth compare favorably to other approaches to curvature estimation proposed in the literature, providing either greater accuracy or greater freedom from dark energy modeling assumptions, and are complementary due to the use of independent data sets. Model-independent estimates of curvature are critical for both testing inflation and obtaining unbiased constraints on dark energy parameters.
Book Synopsis The Theory of Cosmic Aberration by : Leonard Parish
Download or read book The Theory of Cosmic Aberration written by Leonard Parish and published by . This book was released on 1981 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Redshift Connection by : S. A. Milianowicz
Download or read book Redshift Connection written by S. A. Milianowicz and published by . This book was released on 1995 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the early years of cosmological redshift discovery choice had to be made between the phenomena of velocity-shifts & those of photon energy loss, as the cause of these redshifts. In his book "The Observational Approach to Cosmology" (Oxford University Press, 1937) Edwin Hubble gives a very lucid description of reasons for velocity-shifts being accepted as true sources of redshift. Photon energy loss was, at that time believed to be "some unknown reaction between the light & the medium through which it travels" quoting from page 45 of Hubble's book. REDSHIFT CONNECTION provides a rigorous, quantitative analysis of gravitational interaction of mass with electromagnetic radiation, where gravitational field of a photon is not regarded as being negligibly small & its inclusion in the calculations shows that gravity rather than spacetime expansion is the true cause of cosmological redshift. Other, related, paradigms are examined in the light of this finding, such as: gravitational vs. inertial mass, production of long range force, nature of dark matter & the source of cosmic background radiation. The ideas presented in REDSHIFT CONNECTION put in question many presently held theories, not only in the study of Astronomy & Cosmology, but in all of Physics. Order from: Arysutt AMS, P.O. Box 119, Trafford, PA 15085-0119; 412-327-6565.
Book Synopsis Observational Constraints on Dark Energy Cosmological Model Parameters by : Muhammad Omer Farooq
Download or read book Observational Constraints on Dark Energy Cosmological Model Parameters written by Muhammad Omer Farooq and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The expansion rate of the Universe changes with time, initially slowing (decelerating) when the universe was matter dominated, because of the mutual gravitational attraction of all the matter in it, and more recently speeding up (accelerating). A number of cosmological observations now strongly support the idea that the Universe is spatially flat (provided the dark energy density is at least approximately time independent) and is currently undergoing an accelerated cosmological expansion. A majority of cosmologists consider "dark energy" to be the cause of this observed accelerated cosmological expansion. The "standard" model of cosmology is the spatially-flat ACDM model. Although most predictions of the ACDM model are reasonably consistent with measurements, the ACDM model has some curious features. To overcome these difficulties, different Dark Energy models have been proposed. Two of these models, the XCDM parametrization and the slow rolling scalar field model [phi]CDM, along with "standard" ACDM, with the generalization of XCDM and [phi]CDM in non-flat spatial geometries are considered here and observational data are used to constrain their parameter sets. In this thesis, we start with a overview of the general theory of relativity, Friedmann's equations, and distance measures in cosmology. In the following chapters we explain how we can constrain the three above mentioned cosmological models using three data sets: measurements of the Hubble parameter H(z), Supernova (SN) apparent magnitudes, and the baryonic acoustic oscillations (BAO) peak length scale, as functions of redshift z. We then discuss constraints on the deceleration-acceleration transition redshift z[subscript]d[subscript]a using unbinned and binned H(z) data. Finally, we incorporate the spatial curvature in the XCDM and [phi]CDM model and determine observational constraints on the parameters of these expanded models.
Book Synopsis Objects of High Redshift by : G.O. Abell
Download or read book Objects of High Redshift written by G.O. Abell and published by Springer. This book was released on 1980-06-30 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of IAU Symposium No. 92, held in Los Angeles, U.S.A., August 28-31, 1979
Book Synopsis Red Shift and the Origin of the Universe by : Heather Hobden
Download or read book Red Shift and the Origin of the Universe written by Heather Hobden and published by . This book was released on 1998-01-01 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:
