scholarly journals Realizing interactions between dark matter and dark energy using k-essence cosmology

2019 ◽  
Vol 34 (27) ◽  
pp. 1950219 ◽  
Author(s):  
Abhijit Bandyopadhyay ◽  
Anirban Chatterjee
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Energy Tensor ◽  
Late Time ◽  
Stress Energy Tensor ◽  
Cosmic Evolution ◽  
Stress Energy ◽  
Constant Potential ◽  
State Stress

In this paper, we exploit dynamics of a [Formula: see text]-essence scalar field to realize interactions between dark components of universe resulting in an evolution consistent with observed features of late-time phase of cosmic evolution. Stress–energy tensor corresponding to a [Formula: see text]-essence Lagrangian [Formula: see text] (where [Formula: see text]) is shown to be equivalent to an ideal fluid with two components having same equation of state. Stress–energy tensor of one of the components may be generated from a constant potential [Formula: see text]-essence Lagrangian of form [Formula: see text] ([Formula: see text] constant) and that of other from another Lagrangian of form [Formula: see text] with [Formula: see text]. We have shown that the unified dynamics of dark matter and dark energy described by a single scalar field [Formula: see text] driven by a [Formula: see text]-essence Lagrangian [Formula: see text] may be viewed in terms of diffusive interactions between the two hypothetical fluid components “1” and “2” with stress–energy tensors equivalent to that of Lagrangians [Formula: see text] and [Formula: see text], respectively. The energy transfer between the fluid components is determined by functions [Formula: see text], [Formula: see text] and their derivatives. Such a realization is shown to be consistent with the Supernova Ia data with certain constraints on the temporal behavior of [Formula: see text]-essence potential [Formula: see text]. We have described a methodology to obtain such constraints.

scholarly journals ΛCDM as a Noether symmetry in cosmology

2020 ◽  
Vol 29 (15) ◽  
pp. 2050104 ◽  
Author(s):  
D. Benisty ◽  
E. I. Guendelman ◽  
E. Nissimov ◽  
S. Pacheva
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Noether Symmetry ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Main Ingredient ◽  
Riemannian Spacetime ◽  
Stress Energy ◽  
Space Distortion ◽  
Conserved Current

The standard [Formula: see text]CDM model of cosmology is formulated as a simple modified gravity coupled to a single scalar field (“darkon”) possessing a nontrivial hidden nonlinear Noether symmetry. The main ingredient in the construction is the use of the formalism of non-Riemannian spacetime volume-elements. The associated Noether conserved current produces stress–energy tensor consisting of two additive parts — dynamically generated dark energy and dark matter components noninteracting among themselves. Noether symmetry breaking via an additional scalar “darkon” potential introduces naturally an interaction between dark energy and dark matter. The correspondence between the [Formula: see text]CDM model and the present “darkon” Noether symmetry is exhibited up to linear order with respect to gravity-matter perturbations. With the Cosmic Chronometers (CC) and the Redshift Space Distortion (RSD) datasets, we study an example for the “darkon” potential that breaks the Noether symmetry and we show that the preservation of this symmetry yields a better fit.

scholarly journals CAN BRANS–DICKE SCALAR FIELD ACCOUNT FOR DARK ENERGY AND DARK MATTER?

2006 ◽  
Vol 21 (15) ◽  
pp. 1241-1248 ◽  
Author(s):  
M. ARIK ◽  
M. C. ÇALIK
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Energy Density ◽  
Late Time ◽  
Energy Contribution ◽  
Time Solution ◽  
The Universe

By using a linearized non-vacuum late time solution in Brans–Dicke cosmology, we account for the 75% dark energy contribution but not for approximately 23% dark matter contribution to the present day energy density of the universe.

Motion of test particles for Weyl-interaction modified gravity

2019 ◽  
Vol 28 (16) ◽  
pp. 2040014
Author(s):  
Hyung Won Lee ◽  
Asghar Qadir
Keyword(s):  
Dark Matter ◽  
Quantum Gravity ◽  
Modified Gravity ◽  
Weyl Tensor ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Satisfactory Explanation ◽  
Test Particles ◽  
Stress Energy ◽  
Hilbert Action

Since LHC has still given no signal of Supersymmetry, though the energy at which the signal was expected has been passed, one is left short of any good candidate for dark matter. We had proposed [A. Qadir, H. W. Lee and K. Y. Kim, Int. J. Mod. Phys. D 26 (2017) 1741001, 10 pp.] a modification of the Einstein–Hilbert action to explicitly display a term of matter and gravity interaction, [Formula: see text]. The hope had been that this would also resolve the problem of Quantum Gravity. However, the argument given for the purpose of quantum gravity, would more naturally lead one to expect the contraction, [Formula: see text], of the Weyl tensor with two copies of the stress–energy tensor rather than the product of the Ricci scalar and the trace of the stress–energy tensor. Here, the attempt is made to see if this prescription will provide a satisfactory explanation of the dark matter at all scales. One would then try to see if the problem of quantum gravity is resolved by the same prescription.

scholarly journals A transition between bouncing hyper-inflation to ΛCDM from diffusive scalar fields

2018 ◽  
Vol 33 (20) ◽  
pp. 1850119 ◽  
Author(s):  
David Benisty ◽  
Eduardo I. Guendelman
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Numerical Solutions ◽  
Diffusion Constant ◽  
Scalar Fields ◽  
Big Bang ◽  
Energy Tensor ◽  
Stress Energy ◽  
Two Measures ◽  
The Universe

We consider the history of the universe from a possible big bang or a bounce into a late period of a unified interacting dark energy–dark matter model. The model is based on the Two Measures Theories (TMT) which introduces a metric independent volume element and this allows us to construct a unification of dark energy and dark matter. A generalization of the Two Measures Theories gives a diffusive nonconservative stress-energy–momentum tensor in addition to the conserved stress-energy tensor which appear in Einstein equations. These leads to a formulation of interacting DE–DM dust models in the form of a diffusive-type interacting Unified Dark Energy and Dark Matter scenario. The deviation from [Formula: see text]CDM is determined by the diffusion constant [Formula: see text]. For [Formula: see text] the model is indistinguishable from [Formula: see text]CDM. Numerical solutions of the theories show that in some [Formula: see text] the evolution of the early universe is governed by Stiff equation of state or the universe bounces to hyper-inflation. But all of those solutions have a final transition to [Formula: see text]CDM as a stable fixed point for the late universe.

Vacuum stress-energy tensor of a massive scalar field in a wormhole spacetime

2010 ◽  
Vol 81 (8) ◽  
Author(s):  
V. B. Bezerra ◽  
E. R. Bezerra de Mello ◽  
N. R. Khusnutdinov ◽  
S. V. Sushkov
Keyword(s):  
Scalar Field ◽  
Energy Tensor ◽  
Massive Scalar ◽  
Stress Energy Tensor ◽  
Massive Scalar Field ◽  
Stress Energy

scholarly journals EXACT SOLUTIONS OF BRANS–DICKE WORMHOLES IN THE PRESENCE OF MATTER

2011 ◽  
Vol 26 (40) ◽  
pp. 3067-3076 ◽  
Author(s):  
NADIEZHDA MONTELONGO GARCIA ◽  
FRANCISCO S. N. LOBO
Keyword(s):  
Scalar Field ◽  
Vacuum Solution ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Exotic Matter ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Normal Matter ◽  
Stress Energy

A fundamental ingredient in wormhole physics is the presence of exotic matter, which involves the violation of the null energy condition. Although a plethora of wormhole solutions have been explored in the literature, it is useful to find geometries that minimize the usage of exotic matter. In this work, we find exact wormhole solutions in Brans–Dicke theory where the normal matter threading the wormhole satisfies the null energy condition throughout the geometry. Thus, the latter implies that it is the effective stress–energy tensor containing the scalar field, that plays the role of exotic matter, that is responsible for sustaining the wormhole geometry. More specifically, we consider a zero redshift function and a particular choice for the scalar field and determine the remaining quantities, namely, the stress–energy tensor components and the shape function. The solution found is not asymptotically flat, so that this interior wormhole spacetime needs to be matched to an exterior vacuum solution.

scholarly journals Interacting Dark Matter andq-Deformed Dark Energy Nonminimally Coupled to Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-17
Author(s):  
Emre Dil
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Theoretical Description ◽  
Late Time ◽  
Dynamical Structure ◽  
Dark Sector ◽  
Accelerating Expansion ◽  
Stable Attractor ◽  
The Universe

In this paper, we propose a new approach to study the dark sector of the universe by considering the dark energy as an emergingq-deformed bosonic scalar field which is not only interacting with the dark matter, but also nonminimally coupled to gravity, in the framework of standard Einsteinian gravity. In order to analyze the dynamic of the system, we first give the quantum field theoretical description of theq-deformed scalar field dark energy and then construct the action and the dynamical structure of this interacting and nonminimally coupled dark sector. As a second issue, we perform the phase-space analysis of the model to check the reliability of our proposal by searching the stable attractor solutions implying the late-time accelerating expansion phase of the universe.

scholarly journals Local zeta regularization and the scalar Casimir effect III. The case with a background harmonic potential

2015 ◽  
Vol 30 (35) ◽  
pp. 1550213 ◽  
Author(s):  
Davide Fermi ◽  
Livio Pizzocchero
Keyword(s):  
Scalar Field ◽  
General Framework ◽  
Casimir Effect ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Harmonic Potential ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Expectation Value ◽  
Stress Energy

Applying the general framework for local zeta regularization proposed in Part I of this series of papers, we renormalize the vacuum expectation value of the stress-energy tensor (and of the total energy) for a scalar field in presence of an external harmonic potential.

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