scholarly journals Tachyonic Teleparallel Dark Energy in Phase Space

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Behnaz Fazlpour ◽  
Ali Banijamali
Keyword(s):  
Dark Energy ◽  
Phase Space ◽  
Scalar Field ◽  
Critical Points ◽  
Dynamical Analysis ◽  
Accelerating Universe ◽  
Nonminimal Coupling ◽  
Tachyon Field ◽  
Critical Lines

Recently, nonminimal coupling between a noncanonical scalar field and gravity in the framework of teleparallelism has been proposed. Noncanonical scalar field is tachyon field, and the model is known as tachyonic teleparallel dark energy. Here, we perform a dynamical analysis of the model, find its critical points, and study their stability. We find that all the critical points are dark energy dominated solutions corresponding to an accelerating universe. It is also shown that there exist two critical lines which are stable attractors of the model.

scholarly journals RECONSTRUCTING A STRING-INSPIRED NONMINIMALLY COUPLED QUINTOM MODEL

2009 ◽  
Vol 18 (08) ◽  
pp. 1291-1301 ◽  
Author(s):  
M. R. SETARE ◽  
J. SADEGHI ◽  
A. R. AMANI
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
String Theory ◽  
Scalar Curvature ◽  
Recent Work ◽  
Nonminimal Coupling ◽  
Tachyon Field ◽  
Dynamical Dark Energy

Motivated by the recent work of Zhang and Chen,1we generalize their work to the nonminimally coupled case. We consider a quintom model of dark energy with a single scalar field T given by a Lagrangian inspired by a tachyonic Lagrangian in string theory. We consider nonminimal coupling of the tachyon field to the scalar curvature, and then we reconstruct this model in the light of three forms of parametrization for dynamical dark energy.

scholarly journals FERMIONIC AND SCALAR FIELDS AS SOURCES OF INTERACTING DARK MATTER–DARK ENERGY

2011 ◽  
Vol 20 (13) ◽  
pp. 2543-2558 ◽  
Author(s):  
SAMUEL LEPE ◽  
JAVIER LORCA ◽  
FRANCISCO PEÑA ◽  
YERKO VÁSQUEZ
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Analytical Solution ◽  
Scalar Fields ◽  
Nonminimal Coupling ◽  
Field Equations ◽  
Fermionic Field ◽  
Minimal Coupling ◽  
Constant Type

From a variational action with nonminimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a Friedmann–Lemaître–Robertson–Walker (FLRW) metric, the equations lead directly to a cosmological model consisting of two interacting fluids, where the scalar field fluid is interpreted as dark energy and the fermionic field fluid is interpreted as dark matter. Several cases were studied analytically and numerically. An important feature of the non-minimal coupling is that it allows crossing the barrier from a quintessence to phantom behavior. The insensitivity of the solutions to one of the parameters of the model permits it to find an almost analytical solution for the cosmological constant type of universe.

scholarly journals INTERACTING HOLOGRAPHIC TACHYON MODEL OF DARK ENERGY

2010 ◽  
Vol 19 (05) ◽  
pp. 573-586 ◽  
Author(s):  
ALBERTO ROZAS-FERNÁNDEZ ◽  
DAVID BRIZUELA ◽  
NORMAN CRUZ
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Parameter Space ◽  
Holographic Dark Energy ◽  
Accelerated Expansion ◽  
Tachyon Field ◽  
Dark Sector ◽  
Friedmann Robertson Walker

We propose a holographic tachyon model of dark energy with interaction between the components of the dark sector. The correspondence between the tachyon field and the holographic dark energy densities allows the reconstruction of the potential and the dynamics of the tachyon scalar field in a flat Friedmann–Robertson–Walker universe. We show that this model can describe the observed accelerated expansion of our universe with a parameter space given by the most recent observational results.

Dynamical features of a quintom dark energy model with Galileon corrections

2019 ◽  
Vol 28 (01) ◽  
pp. 1950018 ◽  
Author(s):  
Mihai Marciu ◽  
Dana Maria Ioan ◽  
Florin Vlad Iancu
Keyword(s):  
Dark Energy ◽  
Phase Space ◽  
Scalar Field ◽  
Dark Energy Model ◽  
System Analysis ◽  
Present Model ◽  
Scalar Fields ◽  
Independent Manner ◽  
Interaction Terms ◽  
Dynamical Features

In this work, we propose a new dark energy cosmological model, by considering a new quintom scenario which is based on the superposition between a quintessence scalar field and a noncanonical scalar field, both nonminimally coupled with cubic self-interaction terms. Considering that the two scalar fields of the quintom construction are nonminimally coupled in an independent manner with cubic self-interactions terms in the corresponding action, we have analyzed the dynamical features of the present model in the phase-space. By performing a dynamical system analysis in the case of exponential potentials, we have analyzed the structure of the phase-space, obtaining different possible constraints for the parameters of the model which correspond to distinct evolution scenarios.

scholarly journals Interacting dark energy model in the brane scenario: A dynamical system analysis

2019 ◽  
Vol 16 (08) ◽  
pp. 1950115
Author(s):  
Sujay Kr. Biswas ◽  
Subenoy Chakraborty
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Critical Points ◽  
System Analysis ◽  
Evolution Equations ◽  
Field Potential ◽  
Brane Cosmology ◽  
Brane Model ◽  
Barotropic Equation

The present work is a second in the series of investigations of the background dynamics in brane cosmology when dark energy is coupled to dark matter by a suitable interaction. Here, dark matter is chosen in the form of perfect fluid with barotropic equation of state, while a real scalar field with self-interacting potential is chosen as dark energy. The scalar field potential is chosen as exponential or hyperbolic in nature and three different choices for the interactions between the dark species are considered. In the background of spatially flat, homogeneous and isotropic Friedmann–Robertson–Walker (FRW) brane model, the evolution equations are reduced to an autonomous system by suitable transformation of variables and a series of critical points are obtained for different interactions. By analyzing the critical points, we have found a cosmologically viable model describing an early inflationary scenario to dark energy-dominated era connecting through a matter-dominated phase.

scholarly journals Dynamical system analysis of dark energy models in scalar coupled Metric-Torsion theories

2017 ◽  
Vol 26 (13) ◽  
pp. 1750149 ◽  
Author(s):  
Arshdeep Singh Bhatia ◽  
Sourav Sur
Keyword(s):  
Dark Energy ◽  
Phase Space ◽  
Scalar Field ◽  
System Analysis ◽  
Coupling Parameter ◽  
Cosmological Parameters ◽  
Direct Interaction ◽  
Cosmic Acceleration ◽  
Energy Models ◽  
Space Dynamics

We study the phase-space dynamics of cosmological models in the theoretical formulations of nonminimal metric-torsion couplings with a scalar field, and investigate in particular the critical points (CPs) which yield stable solutions exhibiting cosmic acceleration driven by the dark energy (DE). The latter is so defined that it effectively has no direct interaction with the cosmological fluid, although in an equivalent scalar–tensor cosmological setup, the scalar field interacts with the fluid (which we consider to be the pressureless dust). Determining the conditions for the existence of the stable CPs, we check their physical viability in both Einstein and Jordan frames. We also verify that in either of these frames, the evolution of the universe at the corresponding stable points matches with that given by the respective exact solutions we have found in an earlier work [S. Sur and A. S. Bhatia, arXiv:1611.00654 [gr-qc]]. We not only examine the regions of physical relevance in the phase-space when the coupling parameter is varied, but also demonstrate the evolution profiles of the cosmological parameters of interest along fiducial trajectories in the effectively noninteracting scenarios, in both Einstein and Jordan frames.

scholarly journals Dynamics of nonlinear interacting dark energy models

2019 ◽  
Vol 28 (12) ◽  
pp. 1950161 ◽  
Author(s):  
Andronikos Paliathanasis ◽  
Supriya Pan ◽  
Weiqiang Yang
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Critical Points ◽  
Cosmological Parameters ◽  
Late Time ◽  
Interacting Dark Energy ◽  
Energy Models ◽  
Flrw Universe ◽  
The Stability ◽  
Interacting Dark Energy Models

We investigate the cosmological dynamics of interacting dark energy models in which the interaction function is nonlinear in terms of the energy densities. Considering explicitly the interaction between a pressureless dark matter and a scalar field, minimally coupled to Einstein gravity, we explore the dynamics of the spatially flat FLRW universe for the exponential potential of the scalar field. We perform the stability analysis for three nonlinear interaction models of our consideration through the analysis of critical points and we investigate the cosmological parameters and discuss the physical behavior at the critical points. From the analysis of the critical points we find a number of possibilities that include the stable late-time accelerated solution, [Formula: see text]CDM-like solution, radiation-like solution and moreover the unstable inflationary solution.

Generalized tachyonic dark energy

2022 ◽  
Author(s):  
Elham Nouri ◽  
Hossein Motavalli ◽  
Amin Rezaei Akbarieh
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Matter Field ◽  
Cosmic Acceleration ◽  
Coefficient Function ◽  
Tachyon Field ◽  
Evolution Of The Universe ◽  
Coupling Parameters ◽  
Tachyonic Dark Energy ◽  
The Universe

In this paper, a generalized tachyonic dark energy scenario is presented in the framework of a homogeneous and isotropic Friedmann–Lemaître–Robertson–Walker (FLRW) flat universe, in which a noncanonical scalar field is coupled to gravity nonminimally. By utilizing the Noether symmetry method, we found the explicit form of both potential density and coupling function, as a function of the scalar field. It is found that the tachyon field acts as the source of inflation and accelerates the evolution of the universe in the early times considerably. While, in the late times, gravitational sources are a pressureless matter field together with the tachyon field, which is the nature of dark energy and plays an essential role in the deceleration-acceleration phase transition of the universe. Further, the role of the coefficient function of tachyon potential, alongside the potential, is considered in the evolution of the universe. It is shown that this model involves a cosmological degeneracy in the sense that different coupling parameters and tachyonic potentials may be equivalent to the same cosmological standards such as the cosmic acceleration, age, equation of state and mean Hubble of the FLRW universe. The physical characteristics of the main cosmological observables are studied in detail, which suggests that the generalized tachyon field is a remarkable dark energy candidate.

scholarly journals Dynamics of Generalized Tachyon Field in Teleparallel Gravity

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Behnaz Fazlpour ◽  
Ali Banijamali
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Dark Energy Model ◽  
Teleparallel Gravity ◽  
Energy Model ◽  
Tachyon Field ◽  
Coincidence Problem

We study dynamics of generalized tachyon scalar field in the framework of teleparallel gravity. This model is an extension of tachyonic teleparallel dark energy model which has been proposed by Banijamali and Fazlpour (2012). In contrast with tachyonic teleparallel dark energy model that has no scaling attractors, here we find some scaling attractors which means that the cosmological coincidence problem can be alleviated. Scaling attractors are presented for both interacting and noninteracting dark energy and dark matter cases.

scholarly journals Tachyon field as a dark energy in Bianchi type-V spacetime

2015 ◽  
Vol 30 (01) ◽  
pp. 1550008 ◽  
Author(s):  
J. Sadeghi ◽  
H. Farahani
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Equation Of State ◽  
Bianchi Type ◽  
Scalar Potential ◽  
State Parameter ◽  
Tachyon Field ◽  
Equation Of State Parameter ◽  
Type V ◽  
Bianchi Type V

In this paper, we consider Bianchi type-V spacetime and study a cosmological model of dark energy based on tachyon scalar field. We assumed three different kinds of matter without possibility of interaction with scalar dark energy. Assuming power law Hubble parameter in terms of scale factor we obtain evolution of scalar field, scalar potential and equation of state parameter.

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