Interacting phantom cosmology via Noether symmetry approach

2020 ◽  
Vol 17 (12) ◽  
pp. 2050179
Author(s):  
Yusuf Kucukakca
Keyword(s):  
Scalar Field ◽  
Cosmological Solution ◽  
State Parameter ◽  
Noether Symmetry ◽  
Accelerated Expansion ◽  
Effective Equation ◽  
Phantom Divide ◽  
Symmetry Approach ◽  
Phantom Divide Line ◽  
Phantom Scalar

In this paper, we have presented a cosmological model where a phantom scalar field is minimally coupled to dark matter component. Noether symmetry method was applied both to investigate the cosmological solution and to find out what is the form of the potential of scalar field and the unknown function in the considered model. By using this method, these forms are resulted as trigonometric functions. Also, the obtained cosmological solutions are compatible with observations describing the accelerated expansion of the Universe. Furthermore, it turns out that the effective equation of state parameter in the model can cross the phantom divide line.

Theoretical constraints on kinetic k-essence dark energy model in El-Nabulsi fractional action cosmology

2013 ◽  
Vol 91 (10) ◽  
pp. 844-849 ◽  
Author(s):  
Antonio Pasqua ◽  
Surajit Chattopadhyay
Keyword(s):  
Scalar Field ◽  
Dark Energy Model ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Kinetic Term ◽  
Phantom Divide ◽  
Fractional Action Cosmology ◽  
Present Universe ◽  
Phantom Divide Line ◽  
The Universe

In this work, we considered an effective scalar field theory described by a Lagrangian with a noncanonical kinetic term, which leads to accelerated expansion in the present Universe and is known as k-essence in the framework of the fractional action cosmology recently introduced by El-Nabulsi. We have chosen a particular ansatz for the scale factor and the scalar field, in which both are described as a power-law of the time, t. We have studied the behavior of some cosmological quantities in other models to obtain some useful information about the model considered. We observed that the equation of state parameter, w, has decreasing behavior and it never crosses the phantom divide line (i.e., w = –1). Studying the statefinder pair {r, s} and {w, w′}, we observed that the model considered is able to obtain the ΛCDM phase of the Universe.

scholarly journals Bulk viscosity in F(T, TG) gravity

2017 ◽  
Vol 95 (3) ◽  
pp. 262-266
Author(s):  
M. Sharif ◽  
Kanwal Nazir
Keyword(s):  
Equation Of State ◽  
Bulk Viscosity ◽  
State Parameter ◽  
Time Dependent ◽  
Effective Equation ◽  
Phantom Divide ◽  
Equation Of State Parameter ◽  
Phantom Divide Line ◽  
Dependent Viscosity ◽  
The Universe

The present paper is devoted to exploring the effect of bulk viscosity in the context of F(T, TG) gravity. We consider a time-dependent viscosity model with a particular expression of Hubble parameter. We evaluate viscous effective equation of state parameter for three well-known F(T, TG) models. The behavior of the accelerated expanding universe is explored graphically through the viscous equation of state parameter. This parameter indicates the phantom-dominated era as well as crosses the phantom divide line for all three models. We conclude that the universe shows a transition from quintessence to phantom region in the presence of bulk viscosity.

scholarly journals Barrow HDE model for statefinder diagnostic in FLRW universe

2021 ◽  
pp. 2150030
Author(s):  
Anirudh Pradhan ◽  
Archana Dixit ◽  
Vinod Kumar Bhardwaj
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Density Parameter ◽  
Phantom Divide ◽  
Phantom Divide Line ◽  
Expansion Of The Universe ◽  
Flrw Universe ◽  
The Universe

We have analyzed the Barrow holographic dark energy (BHDE) in the framework of flat FLRW universe by considering the various estimations of Barrow exponent △. Here, we define BHDE, by applying the usual holographic principle at a cosmological system, for utilizing the Barrow entropy rather than the standard Bekenstein–Hawking. To understand the recent accelerated expansion of the universe, consider the Hubble horizon as the IR cutoff. The cosmological parameters, especially the density parameter [Formula: see text], the equation of the state parameter [Formula: see text], energy density [Formula: see text] and the deceleration parameter [Formula: see text] are studied in this paper and found the satisfactory behaviors. Moreover we additionally focus on the two geometric diagnostics, the statefinder [Formula: see text] and [Formula: see text] to discriminant BHDE model from the [Formula: see text]CDM model. Here we determined and plotted the trajectories of evolution for statefinder [Formula: see text], [Formula: see text] and [Formula: see text] diagnostic plane to understand the geometrical behavior of the BHDE model by utilizing Planck 2018 observational information. Finally, we have explored the new Barrow exponent △, which strongly affects the dark energy equation of state that can lead it to lie in the quintessence regime, phantom regime and exhibits the phantom-divide line during the cosmological evolution.

Tsallis holographic dark energy with hybrid expansion law

2020 ◽  
Vol 17 (11) ◽  
pp. 2050144 ◽  
Author(s):  
Vandna Srivastava ◽  
Umesh Kumar Sharma
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Accelerated Expansion ◽  
Eos Parameter ◽  
Phantom Divide ◽  
Accelerating Expansion ◽  
Phantom Divide Line ◽  
Phantom Scalar ◽  
The Rich ◽  
The Universe

In this work, we explore the Tsallis holographic dark energy (THDE) model with IR cutoff as Granda–Oliveros horizon describing the Universe experiencing an accelerating expansion phase in the framework of flat Friedmann–Lemaître–Robertson–Walker (FLRW) Universe. The Universe evolution from earlier decelerated to the current accelerated phase is exhibited by the deceleration parameter acquired in the THDE model. By the value of the Tsallis parameter [Formula: see text], the equation of state (EoS) parameter for the THDE model represents the rich behavior of the Cosmos as, the quintessence era ([Formula: see text]), crossing the phantom divide line and phantom era ([Formula: see text]). The squared sound speed [Formula: see text] also suggests that the THDE model is classically stable at present. Also, the correspondence with the quintessence and phantom scalar field for the THDE model is analyzed to describe the accelerated expansion of the Universe.

scholarly journals Noether symmetries of Einstein-aether scalar field cosmology

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Yusuf Kucukakca ◽  
Amin Rezaei Akbarieh
Keyword(s):  
Scalar Field ◽  
Noether Symmetry ◽  
Accelerated Expansion ◽  
Noether Symmetries ◽  
Field Equations ◽  
Symmetry Approach ◽  
Expansion Of The Universe ◽  
Frw Metric ◽  
Scalar Field Cosmology ◽  
The Universe

AbstractIn this paper, we explore an Einstein-aether cosmological model by adding the scalar field in which it has an interaction with the aether field. For the cosmological implications of the model, we consider that the universe can be described by the spatially flat FRW metric together with the matter dominated universe. Applying Noether symmetry approach to the point-like Lagrangian we determine the explicit forms of unknown functions i.e. the potential and coupling function. We solve the analytical cosmological solutions of the field equations admitting the Noether symmetry, basically divided into two parts. Our results show that the obtained solutions lead to an accelerated expansion of the universe. We also discuss the tensor perturbations within the framework of this model in order to get information about the mass of gravitational waves.

INTERACTING GENERALIZED DARK ENERGY AND RECONSTRUCTION OF SCALAR FIELD MODELS

2013 ◽  
Vol 28 (38) ◽  
pp. 1350180 ◽  
Author(s):  
M. SHARIF ◽  
ABDUL JAWAD
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Dark Energy Model ◽  
Cold Dark Matter ◽  
Scalar Potential ◽  
Scalar Fields ◽  
Phantom Divide ◽  
Evolution Parameter ◽  
Scalar Field Models ◽  
Phantom Divide Line

In this paper, we consider the interacting generalized dark energy with cold dark matter and analyze the behavior of evolution parameter via dark energy and interacting parameters. It is found that the evolution parameter crosses the phantom divide line in most of the cases of integration constants. We also establish the correspondence of scalar field models (quintessence, k-essence and dilaton) with this dark energy model in which scalar fields show the increasing behavior. The scalar potential corresponds to attractor solutions in quintessence case.

Brans–Dicke type teleparallel scalar–tensor theory

2017 ◽  
Vol 32 (34) ◽  
pp. 1750183 ◽  
Author(s):  
Mustafa Salti ◽  
Oktay Aydogdu ◽  
Hilmi Yanar ◽  
Figen Binbay
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Scalar Field ◽  
Noether Symmetry ◽  
Scalar Tensor Theory ◽  
Minimal Coupling ◽  
Energy Effect ◽  
New Model ◽  
Symmetry Approach ◽  
Tensor Theory

The teleparallel alternative of general relativity which is based on torsion instead of curvature is considered as the gravitational sector to explore the dark universe. Inspired from the well-known Brans–Dicke gravity, here, we introduce a new proposal for the galactic dark energy effect. The new model includes a scalar field with self-interacting potential and a non-minimal coupling between the gravity and scalar field. Additionally, we analyze the idea via the Noether symmetry approach and thermodynamics.

scholarly journals CHAMELEON COSMOLOGY MODEL DESCRIBING THE PHANTOM DIVIDE LINE CROSSING

2011 ◽  
Vol 20 (02) ◽  
pp. 121-131 ◽  
Author(s):  
FRANCESCO CANNATA ◽  
ALEXANDER Y. KAMENSHCHIK
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Phantom Divide ◽  
Model Based ◽  
Independent Functions ◽  
Phantom Divide Line ◽  
Line Crossing

An exact solution describing the evolution of the type Bang-to-Rip with the phantom divide line crossing is constructed in the chameleon cosmology model, based on two independent functions of the scalar field.

Anisotropic Dark Energy Cosmological Model with Cosmic Strings

2020 ◽  
Author(s):  
T. Vinutha ◽  
V.U.M. Rao ◽  
Molla Mengesha
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Model ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Physical Parameters ◽  
Type I ◽  
Field Equations ◽  
Eos Parameter ◽  
Phantom Divide

The present study deals with a spatially homogeneous locally rotationally symmetric (LRS) Bianchi type-I dark energy cosmological model containing one dimensional cosmic string fluid source. The Einstein's field equations are solved by using a relation between the metric potentials and hybrid expansion law of average scale factor. We discuss accelerated expansion of our model through equation of state (ωde) and deceleration parameter (q). We observe that in the evolution of our model, the equation of state parameter starts from matter dominated phase ωde > -1/3 and ultimately attains a constant value in quintessence region (-1 < ωde < -1/3). The EoS parameter of the model never crosses the phantom divide line (ωde = 1). These facts are consistent with recent observations. We also discuss some other physical parameters.

scholarly journals NETWORKS OF COSMOLOGICAL HISTORIES, CROSSING OF THE PHANTOM DIVIDE LINE AND POTENTIALS WITH CUSPS

2007 ◽  
Vol 16 (10) ◽  
pp. 1683-1704 ◽  
Author(s):  
FRANCESCO CANNATA ◽  
ALEXANDER Y. KAMENSHCHIK
Keyword(s):  
Scalar Field ◽  
Equations Of Motion ◽  
Space Time ◽  
Cosmological Models ◽  
Mechanical Analogy ◽  
Phantom Divide ◽  
Phantom Divide Line

We discuss the phenomenon of the smooth dynamical gravity induced crossing of the phantom divide line in a framework of simple cosmological models where it appears to occur rather naturally, provided the potential of the unique scalar field has some kind of cusp. The behavior of cosmological trajectories in the vicinity of the cusp is studied in some detail and a simple mechanical analogy is presented. The phenomenon of certain complementarity between the smoothness of the space–time geometry and matter equations of motion is elucidated. We introduce a network of cosmological histories and qualitatively describe some of its properties.

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