scholarly journals Transient crossing of phantom divide line w Λ = − 1 under Gauss–Bonnet interaction

2008 ◽  
Vol 41 (7) ◽  
pp. 1511-1525 ◽  
Author(s):  
Abhik Kumar Sanyal
Keyword(s):  
Phantom Divide ◽  
Phantom Divide Line ◽  
Crossing Of Phantom Divide

scholarly journals VISCOUS DARK ENERGY IN f(T) GRAVITY

2013 ◽  
Vol 28 (27) ◽  
pp. 1350118 ◽  
Author(s):  
M. SHARIF ◽  
SHAMAILA RANI
Keyword(s):  
Dark Energy ◽  
Graphical Representation ◽  
Teleparallel Gravity ◽  
Eos Parameter ◽  
Phantom Divide ◽  
Accelerating Expansion ◽  
Phantom Divide Line ◽  
Expansion Of The Universe ◽  
Crossing Of Phantom Divide ◽  
The Universe

We study the bulk viscosity taking dust matter in the generalized teleparallel gravity. We consider different dark energy (DE) models in this scenario along with a time-dependent viscous model to construct the viscous equation of state (EoS) parameter for these DE models. We discuss the graphical representation of this parameter to investigate the viscosity effects on the accelerating expansion of the universe. It is mentioned here that the behavior of the universe depends upon the viscous coefficients showing the transition from decelerating to accelerating phase. It leads to the crossing of phantom divide line and becomes phantom dominated for specific ranges of these coefficients.

Role of collisional matter in the framework of extended teleparallel theory

2020 ◽  
Vol 29 (15) ◽  
pp. 2050099
Author(s):  
Muhammad Zeeshan ◽  
M. Zubair ◽  
Rabia Saleem
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Power Law ◽  
Phantom Divide ◽  
Evolutionary Scenario ◽  
Cosmic Evolution ◽  
Phantom Divide Line ◽  
Teleparallel Theory ◽  
Crossing Of Phantom Divide

The purpose of this work is to examine the cosmic evolution in the presence of collisional matter (CM) with and without radiations in a modified Teleparallel theory involving a generic function [Formula: see text] which depends on the scalar torsion [Formula: see text] and the boundary term associated to the divergence of torsion [Formula: see text]. We select seven novel [Formula: see text] models including power law, logarithmic models and exponential models, some of these reported in [S. Bahamonde, M. Zubair and G. Abbas, Phys. Dark Univ. 19 (2018) 78; S. Bahamonde and S. Capozziello, The Eur. Phys. J. C. 77 (2017) 107; C. Escamilla-Rivera and J. L. Said, Class. Quantum Grav. 37 (2020) 165002] and discuss the evolutionary scenario. The behavior of deceleration parameter [Formula: see text], Hubble parameter [Formula: see text], Equation-of-state (EoS) for dark energy (DE) and effective EoS is presented. [Formula: see text]CDM epoch and crossing of phantom divide line (approaching to phantom era) is observed in scenarios like noncollisional matter (NCM) with radiation, CM with and without radiation. Results are found to be adequate with recent cosmic observations.

Phantom crossing with collisional matter in f(T) gravity

2016 ◽  
Vol 25 (05) ◽  
pp. 1650057 ◽  
Author(s):  
M. Zubair
Keyword(s):  
Dark Energy ◽  
Late Time ◽  
Eos Parameter ◽  
Phantom Divide ◽  
Phantom Crossing ◽  
Phantom Divide Line ◽  
C 71 ◽  
Scalar Theories ◽  
The One ◽  
Crossing Of Phantom Divide

We study the late-time cosmological evolution of [Formula: see text] (where [Formula: see text] is the torsion scalar) theories with matter contents consisting of collisional self-interacting matter and radiations. The power law, exponential and logarithmic [Formula: see text] models are considered to explore the evolution of Hubble parameter [Formula: see text], dark energy (DE) equation of state (EoS) [Formula: see text] and effective EoS parameter [Formula: see text]. We show that crossing of phantom divide line can be realized in the presence of collisional matter as compared to the results obtained for the choice of noncollisional matter [K. Bamba, C.-Q. Geng, C.-C. Lee and L.-W. Luo, J. Cosmol. Astropart. Phys. 01 (2011) 021; K. Bamba, C.-Q. Geng and C.-C. Lee, arXiv:1008.4036]. The evolutionary behavior of [Formula: see text] is consistent with the one developed in [P. Wu and H. Yu, Eur. Phys. J. C 71 (2011) 1552] and recent observational data [U. Alam, V. Sahni and A. A. Starobinsky, J. Cosmol. Astropart. Phys. 0406 (2004) 008; S. Nesseris and L. Perivolaropoulos, J. Cosmol. Astropart. Phys. 0701 (2007) 018; P. Wu and H. Yu, Phys. Lett. B 643 (2006) 315; U. Alam, V. Sahni and A. A. Starobinsky, J. Cosmol. Astropart. Phys. 0702 (2007) 011; H. K. Jassal, J. S. Bagla and T. Padmanabhan, Mon. Not. R. Astron. Soc. 405 (2010) 2639].

scholarly journals COSMOLOGICAL ASPECTS OF A VECTOR FIELD MODEL

2012 ◽  
Vol 21 (07) ◽  
pp. 1250063 ◽  
Author(s):  
S. DAVOOD SADATIAN
Keyword(s):  
Vector Field ◽  
Field Model ◽  
Lorentz Invariance ◽  
Normal Vector ◽  
Normal Vector Field ◽  
Phantom Divide ◽  
Invariance Violation ◽  
Phantom Divide Line ◽  
Brane Models ◽  
Crossing Of Phantom Divide

We have studied a DGP-inspired braneworld scenario where the idea of Lorentz invariance violation has been combined into a specifying preferred frame that embed a dynamical normal vector field to brane. We propose the Lorentz violating DGP brane models with enough parameters can explain crossing of phantom divide line. Also we have considered the model for proper cosmological evolution that is according to the observed behavior of the equation of state. In other view point, we have described a Rip singularity solution of model that occur in this model.

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.

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.

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.

scholarly journals Lorenz gauge fixing of f(T) teleparallel cosmology

2017 ◽  
Vol 26 (14) ◽  
pp. 1750154 ◽  
Author(s):  
W. El Hanafy ◽  
G. G. L. Nashed
Keyword(s):  
Degrees Of Freedom ◽  
Teleparallel Gravity ◽  
Phase Portraits ◽  
De Sitter ◽  
Phantom Divide ◽  
Type Iv ◽  
Gauge Fixing ◽  
Phantom Divide Line ◽  
Lorenz Gauge ◽  
The Stability

In teleparallel gravity, we apply Lorenz type gauge fixing to cope with redundant degrees of freedom in the vierbein field. This condition is mainly to restore the Lorentz symmetry of the teleparallel torsion scalar. In cosmological application, this technique provides standard cosmology, turnaround, bounce or [Formula: see text]CDM as separate scenarios. We reconstruct the [Formula: see text] gravity which generates these models. We study the stability of the solutions by analyzing the corresponding phase portraits. Also, we investigate Lorenz gauge in the unimodular coordinates, it leads to unify a nonsingular bounce and Standard Model cosmology in a single model, where crossing the phantom divide line is achievable through a finite-time singularity of Type IV associated with a de Sitter fixed point. We reconstruct the unimodular [Formula: see text] gravity which generates the unified cosmic evolution showing the role of the torsion gravity to establish a healthy bounce scenario.

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