scholarly journals Scalar field with the source in the form of the stress-energy tensor trace as a dark energy model

2016 ◽  
Vol 22 (4) ◽  
pp. 368-373
Author(s):  
I. G. Dudko ◽  
Yu. P. Vyblyi
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Dark Energy Model ◽  
Energy Model ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Stress Energy

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.

Reconstructing Tsallis holographic quintessence

2021 ◽  
Author(s):  
Umesh Kumar Sharma ◽  
Vandna Srivastava
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Quantum Gravity ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Energy Model ◽  
Holographic Dark Energy Model ◽  
The Universe ◽  
Modified Entropy

Within the framework of quantum gravity and modified entropy-area formalism, the Tsallis holographic dark energy is an effort to peep into a mysterious content of the Universe, the dark energy, to analyze its nature. The Tsallis parameter [Formula: see text] provides the main characteristic of the Tsallis holographic dark energy. Opting the value of Tsallis parameter [Formula: see text], a quintessence scalar field description of the Tsallis holographic dark energy model can be obtained. In this work, we present this quintessential explanation of the Tsallis holographic dark energy with [Formula: see text] and reconstruct the dynamics of the scalar field and the potential of quintessence.

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 CONSTRAINTS ON THAWING SCALAR FIELD MODELS FROM FUNDAMENTAL CONSTANTS

2013 ◽  
Vol 22 (07) ◽  
pp. 1350035 ◽  
Author(s):  
QING GAO ◽  
YUNGUI GONG
Keyword(s):  
Fine Structure ◽  
Dark Energy ◽  
Scalar Field ◽  
Observational Data ◽  
Dark Energy Model ◽  
Structure Constant ◽  
Energy Model ◽  
Fine Structure Constant ◽  
Density Parameter ◽  
Scalar Field Models

We consider a dark energy model with a relation between the equation of state parameter w and the energy density parameter Ωϕ derived from thawing scalar field models. Assuming the variation of the fine structure constant is caused by dark energy, we use the observational data of the variation of the fine structure constant to constrain the current value of w0 and Ωϕ0 for the dark energy model. At the 1σ level, the observational data excluded some areas around w0 = –1, which explains the positive detection of the variation of the fine structure constant at the 1σ level, but ΛCDM model is consistent with the data at the 2σ level.

Sign in / Sign up

Export Citation Format

Share Document