scholarly journals Gravitational Energy as Dark Energy: Concordance of Cosmological Tests

2007 ◽  
Vol 672 (2) ◽  
pp. L91-L94 ◽  
Author(s):  
Ben M. Leith ◽  
S. C. Cindy Ng ◽  
David L. Wiltshire
Keyword(s):  
Dark Energy ◽  
Gravitational Energy ◽  
Cosmological Tests

scholarly journals DARK ENERGY AND THE STATISTICAL STUDY OF THE OBSERVED IMAGE SEPARATIONS OF THE MULTIPLY-IMAGED SYSTEMS IN THE CLASS STATISTICAL SAMPLE

2004 ◽  
Vol 13 (06) ◽  
pp. 1005-1018 ◽  
Author(s):  
ABHA DEV ◽  
DEEPAK JAIN ◽  
SHOBHIT MAHAJAN
Keyword(s):  
Dark Energy ◽  
Statistical Study ◽  
Cosmological Parameters ◽  
Mass Scale ◽  
Gravitational Lens ◽  
Radio Sources ◽  
Sky Survey ◽  
Image Separation ◽  
Cosmological Tests ◽  
Statistical Sample

The present day observations favour a universe which is flat, accelerated and composed of ~ 1/3 matter (baryonic + dark) and ~ 2/3 of a negative pressure component, usually referred to as dark energy or quintessence. The Cosmic Lens All Sky Survey (CLASS), the largest radio-selected galactic mass scale gravitational lens search project to date, has resulted in the largest sample suitable for statistical analysis. In the work presented here, we exploit observed image separations of the multiply-imaged lensed radio sources in the sample. We use two different tests: (1) image separation distribution function n(Δθ) of the lensed radio sources and (2) Δθ pred versus Δθ obs as observational tools to constrain the cosmological parameters w and Ωm. The results are in concordance with the bounds imposed by other cosmological tests.

scholarly journals Unveiling cosmography from the dark energy equation of state

2019 ◽  
Vol 28 (12) ◽  
pp. 1950154 ◽  
Author(s):  
Celia Escamilla-Rivera ◽  
Salvatore Capozziello
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Equation ◽  
Cosmological Parameters ◽  
Cosmic Acceleration ◽  
Type Ia ◽  
State Formula ◽  
Cosmological Tests ◽  
Supernovae Type Ia ◽  
Straightforward Approach

Constraining the dark energy equation of state, [Formula: see text], is one of the main issues of current and future cosmological surveys. In practice, this requires making assumptions about the evolution of [Formula: see text] with redshift [Formula: see text], which can be manifested in a choice of a specific parametric form where the number of cosmological parameters play an important role in the observed cosmic acceleration. Since any attempt to constrain the EoS requires some prior fixing in one form or the other, settling a method to constrain cosmological parameters is of great importance. In this paper, we provide a straightforward approach to show how cosmological tests can be improved via a parametric methodology based on cosmography. Using Supernovae Type IA samplers, we show how by performing a statistical analysis of a specific dark energy parametrization can give directly the cosmographic parameters values.

scholarly journals Gravitational energy as dark energy: Average observational quantities

2010 ◽  
Author(s):  
David L. Wiltshire ◽  
Jean-Michel Alimi ◽  
André Fuözfa
Keyword(s):  
Dark Energy ◽  
Gravitational Energy ◽  
Energy Average

scholarly journals DARK ENERGY, DARK MATTER AND GRAVITY

2007 ◽  
Vol 16 (12a) ◽  
pp. 2003-2012 ◽  
Author(s):  
ORFEU BERTOLAMI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Physical Theory ◽  
Scalar Fields ◽  
High Accuracy ◽  
Scalar Theory ◽  
General Relativistic ◽  
Cosmological Tests ◽  
Theory Of Gravity

We discuss the motivation for high accuracy relativistic gravitational experiments in the solar system and complementary cosmological tests. We focus our attention on the issue of distinguishing a generic scalar theory of gravity as the underlying physical theory from the usual general-relativistic picture, where one expects the presence of fundamental scalar fields associated, for instance, with inflation, dark matter and dark energy.

Cosmological Tests for Minimally Coupled Perturbed Dark Energy

2010 ◽  
Author(s):  
S. Apunevych ◽  
B. Novosyadlyj ◽  
O. Sergijenko
Keyword(s):  
Dark Energy ◽  
Cosmological Tests

THE PUZZLE OF GRAVITATION

2006 ◽  
Vol 21 (31) ◽  
pp. 6315-6321 ◽  
Author(s):  
B. G. SIDHARTH
Keyword(s):  
Dark Energy ◽  
Pion Mass ◽  
Planck Scale ◽  
Hubble Constant ◽  
Residual Energy ◽  
Gravitational Energy ◽  
The Other ◽  
Quantum Vacuum ◽  
The One ◽  
The Universe

We consider a model in which the Universe has an underpinning of oscillators in the quantum vacuum (or dark energy) at the Planck scale and deduce a number of otherwise inexplicable large number relations which have been considered to be empirical accidents. The analysis shows that the gravitational energy is the residual energy of the Planck oscillators constituting the Universe at large on the one hand, and elementary particles on the other. This explains a mysterious puzzle first pointed out by Weinberg several years ago, in a formula relating the pion mass to the Hubble constant, a puzzle which has remained unexplained ever since.

scholarly journals Dynamical Gravity, Expanding Space and Stretching Gedesics

2021 ◽  
Author(s):  
Clive Anthony Redwood
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Hubble Parameter ◽  
State Parameter ◽  
Gravitational Energy ◽  
Density Parameter ◽  
Spatial Expansion ◽  
Tidal Interactions ◽  
Fisher Relation ◽  
Gravitational Processes

Abstract The gravitational natures of phenomena separately attributed to dark matter and dark energy and challenges encountered in identifying such sources motivate enquiry into the capabilities of the field, itself, to generate such phenomena. It is found that, in curvature-free Friedmann-Lemaître-Robertson-Walker and gravitationally perturbed Robertson-Walker spacetimes, gravity has an equation of state parameter w = -1 and negative pressures. Expanding space is proposed as the form of a growing cosmic gravitational field. The gravitational-spatial expansion is locally isobaric. Barotropic gravitational dynamics yield the Hubble-Lemaître law. The expansion results from the induction of gravity by matter, radiation and by itself. Gravitational auto-induction is a dynamical feedback process that produces an isotropic spatial expansion with an invariant Hubble parameter like a ‘cosmological constant’ of density 2H2/κ or, equivalently, of a density parameter of 2/3. The Planck 2018 result is moderately higher at about the 2.5/σ level. A new expression of the Hubble parameter in the late homogeneous universe is obtained. The growth of the field isotropically stretches geodesics. In homogeneous regions, this manifests as the Hubble acceleration of bodies and the redshifting of radiation attributed to dark energy. Geodesics may depend on gravitational energy density that retains its values at comoving locations. In inhomogeneous regions, such retentions lead to similar retentions of circular speeds and deflection angles - geodesic stretching - attributed to clustering dark matter. The baryonic Tully-Fisher relation is explained. Dependence of geodesics on gravitational energy explains tidal interactions as being inertial gravitational processes.

scholarly journals GRAVITATIONAL LENSING STATISTICAL PROPERTIES IN GENERAL FRW COSMOLOGIES WITH DARK ENERGY COMPONENT(S): ANALYTIC RESULTS

2000 ◽  
Vol 09 (05) ◽  
pp. 591-600 ◽  
Author(s):  
ZONG-HONG ZHU
Keyword(s):  
Dark Energy ◽  
Gravitational Lensing ◽  
Cosmological Models ◽  
Distance Measures ◽  
Energy Component ◽  
Dark Energy Component ◽  
Image Separation ◽  
Cosmological Tests ◽  
Age Of The Universe ◽  
The Universe

Various astronomical observations have been consistently making a strong case for the existence of a component of dark energy with negative pressure in the universe. It is now necessary to take the dark energy component(s) into account in gravitational lensing statistics and other cosmological tests. By using the comoving distance we derive analytic but simple expressions for the optical depth of multiple image, the expected value of image separation and the probability distribution of image separation caused by an assemble of singular isothermal spheres in general FRW cosmological models with dark energy component(s). We also present the kinematical and dynamical properties of these kinds of cosmological models and calculate the age of the universe and the distance measures, which are often used in classical cosmological tests. In some cases we are able to give formulae that are simpler than those found elsewhere in the literature, which could make the cosmological tests for dark energy component(s) more convenient.

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