scholarly journals CROSSING OF PHANTOM DIVIDE IN F(R) GRAVITY

2010 ◽  
Vol 25 (11n12) ◽  
pp. 900-908 ◽  
Author(s):  
KAZUHARU BAMBA ◽  
CHAO-QIANG GENG ◽  
SHIN'ICHI NOJIRI ◽  
SERGEI D. ODINTSOV
Keyword(s):  
Explicit Model ◽  
Phantom Divide ◽  
Big Rip ◽  
Crossing Of Phantom Divide ◽  
Reconstructed Model

An explicit model of F(R) gravity with realizing a crossing of the phantom divide is reconstructed. In particular, it is shown that the Big Rip singularity may appear in the reconstructed model of F(R) gravity. Such a Big Rip singularity could be avoided by adding R2 term or non-singular viable F(R) theory1 to the model because phantom behavior becomes transient.

scholarly journals LATE TIME ACCELERATION IN 3-BRANE BRANS–DICKE COSMOLOGY

2008 ◽  
Vol 23 (36) ◽  
pp. 3095-3111
Author(s):  
A. ERRAHMANI ◽  
T. OUALI
Keyword(s):  
Cosmological Parameters ◽  
Late Time ◽  
Observation Data ◽  
Energy Component ◽  
Phantom Divide ◽  
Big Rip ◽  
Dimensional Spacetime ◽  
Dark Energy Component ◽  
Phantom Divide Line ◽  
The Universe

In order to investigate more features of the Brans–Dicke cosmology in the five-dimensional spacetime, we explore the solutions of its dynamical systems. A behavior of the universe in its early and late time by means of the scale factor is considered. As a result, we show that it is possible to avoid the big rip singularity and to cross the phantom divide line. Furthermore, we review the dark energy component of the universe and its agreement with the observation data for this 3-brane Brans–Dicke cosmology by means of the cosmological parameters.

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.

THE MODIFIED CHAPLYGIN GAS AS A UNIFIED DARK SECTOR MODEL

2007 ◽  
Vol 22 (11) ◽  
pp. 783-790 ◽  
Author(s):  
YABO WU ◽  
SONG LI ◽  
JIANBO LU ◽  
XIUYI YANG
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Dark Sector ◽  
Phantom Divide ◽  
Sector Model ◽  
Energy Models ◽  
Big Rip ◽  
The Future

A modified Chaplygin gas (MCG) model of unifying dark energy and dark matter is considered in this paper. Concretely, the evolution of such a unified dark sector model is studied and the statefinder diagnostic to the MCG model is performed in our model. By analysis, it is shown that the state parameter of dark energy can cross the so-called phantom divide ω = -1, the behavior of MCG will be like ΛCDM in the future and therefore our universe will not end up with Big Rip in the future. In addition, we plot the evolution trajectory of the MCG model in the statefinder parameter r–s plane and show the discrimination between this scenario and other dark energy models.

Observations favor the crossing of phantom divide lines

2010 ◽  
Vol 53 (3) ◽  
pp. 562-566 ◽  
Author(s):  
TieTie Huang ◽  
PuXun Wu ◽  
HongWei Yu
Keyword(s):  
Phantom Divide ◽  
Crossing Of Phantom Divide

THE GENERALIZED CHAPLYGIN GAS MODEL WITH INTERACTION

2007 ◽  
Vol 16 (10) ◽  
pp. 1601-1609 ◽  
Author(s):  
YABO WU ◽  
SONG LI ◽  
HAI YANG ZHONG ◽  
LEI LI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Phantom Divide ◽  
Big Rip ◽  
The Future ◽  
Two Fluid

A two-fluid generalized Chaplygin gas (GCG) model including two different cases is considered in this paper. Concretely, the evolution of the GCG model with interaction is discussed and the statefinder diagnostic for the GCG models is performed, respectively. By analysis, we show that the effective state parameter of dark energy can cross the so-called phantom divide ω = -1, the behavior of GCG will be like ΛCDM in the future and therefore our Universe will not end up with the Big Rip in the future. In addition, we find that the statefinder diagnostic can differentiate the GCG model with or without interaction. Also, trajectories of both the GCG model mixed with cold dark matter (CDM) and the pure GCG model in the parameter plane are illustrated to be significantly different.

A VARIABLE MODIFIED CHAPLYGIN GAS MODEL WITH INTERACTION

2009 ◽  
Vol 18 (12) ◽  
pp. 1851-1862 ◽  
Author(s):  
LILI XING ◽  
YUANXING GUI ◽  
CHUNYAN WANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Phantom Divide ◽  
Energy Models ◽  
Big Rip ◽  
Variable Modified Chaplygin Gas ◽  
The Future

We consider in this paper a variable modified Chaplygin gas (VMCG) model for describing the unification of dark energy and dark matter, in which dark energy interacts with dark matter. Concretely, the evolution of the VMCG model with interaction is discussed and the statefinder diagnostic for the model is performed. By analysis, we find that the effective state parameter of dark energy can cross the phantom divide wΛ= -1 and our universe will not end up with a Big Rip in the future. Furthermore, we perform a statefinder analysis on this scenario and show the discrimination between this scenario and other dark energy models.

scholarly journals DARK ENERGY WITH DARK SPINORS

2010 ◽  
Vol 25 (02) ◽  
pp. 101-110 ◽  
Author(s):  
CHRISTIAN G. BÖHMER ◽  
JAMES BURNETT
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Time Frame ◽  
Accelerating Universe ◽  
Phantom Divide ◽  
The Past ◽  
Big Rip ◽  
Reasonable Time Frame ◽  
Spinor Model ◽  
The Universe

Ever since the first observations that we are living in an accelerating universe, it has been asked what dark energy is. There are various explanations, all of which have various drawbacks or inconsistencies. Here we show that using a dark spinor field it is possible to have an equation of state that crosses the phantom divide, becoming a dark phantom spinor which evolves into dark energy. This type of equation of state has been mildly favored by experimental data, however, in the past there were hardly any theories that satisfied this crossing without creating ghosts or causing a singularity which results in the universe essentially ripping. The dark spinor model converges to dark energy in a reasonable time frame avoiding the big rip and without attaining negative kinetic energy as it crosses the phantom divide.

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].

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