scholarly journals SOME BIANCHI TYPE-V MODELS OF ACCELERATING UNIVERSE WITH DARK ENERGY

2011 ◽  
Vol 26 (09) ◽  
pp. 647-659 ◽  
Author(s):  
SURESH KUMAR ◽  
ANIL KUMAR YADAV
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Accelerating Universe ◽  
Anisotropic Universe ◽  
Field Equations ◽  
Bianchi V ◽  
Variable Equation ◽  
Type V ◽  
The Universe

The paper deals with a spatially homogeneous and anisotropic universe filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally together with a special law of variation for the average Hubble's parameter in order to solve the Einstein's field equations. The law yields two explicit forms of the scale factor governing the Bianchi-V spacetime and constant values of deceleration parameter. The role of dark energy with variable equation of state parameter has been studied in detail in the evolution of Bianchi-V universe. It has been found that dark energy dominates the universe at the present epoch, which is consistent with the observations. The universe achieves flatness after the dominance of dark energy. The physical behavior of the universe has been discussed in detail.

scholarly journals Accelerating dark energy cosmological model in two fluids with hybrid scale factor

2017 ◽  
Vol 14 (09) ◽  
pp. 1750124 ◽  
Author(s):  
B. Mishra ◽  
P. K. Sahoo ◽  
Pratik P. Ray
Keyword(s):  
Dark Energy ◽  
Late Phase ◽  
Scale Factor ◽  
Accelerating Universe ◽  
Late Time ◽  
Field Equations ◽  
Geometrical Properties ◽  
Two Fluids ◽  
The Universe

In this paper, we have investigated the anisotropic behavior of the accelerating universe in Bianchi V spacetime in the framework of General Relativity (GR). The matter field we have considered is of two non-interacting fluids, i.e. the usual string fluid and dark energy (DE) fluid. In order to represent the pressure anisotropy, the skewness parameters are introduced along three different spatial directions. To achieve a physically realistic solutions to the field equations, we have considered a scale factor, known as hybrid scale factor, which is generated by a time-varying deceleration parameter. This simulates a cosmic transition from early deceleration to late time acceleration. It is observed that the string fluid dominates the universe at early deceleration phase but does not affect nature of cosmic dynamics substantially at late phase, whereas the DE fluid dominates the universe in present time, which is in accordance with the observations results. Hence, we analyzed here the role of two fluids in the transitional phases of universe with respect to time which depicts the reason behind the cosmic expansion and DE. The role of DE with variable equation of state parameter (EoS) and skewness parameters, is also discussed along with physical and geometrical properties.

THE ROLE OF A CHAMELEON FIELD IN AN ANISOTROPIC UNIVERSE WITH LOGAMEDIATE AND INTERMEDIATE SCENARIOS

2010 ◽  
Vol 25 (24) ◽  
pp. 4691-4701 ◽  
Author(s):  
SHUVENDU CHAKRABORTY ◽  
UJJAL DEBNATH
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Anisotropic Universe ◽  
Anisotropic Model ◽  
Scale Factors ◽  
Slow Roll ◽  
Energy Scalar ◽  
The Universe

In this work, we consider the Universe is being filled with matter composed of a chameleon-type dark energy scalar field. Employing a particular form of potential, we discuss the field's role in the accelerating phase of the Universe for an anisotropic model using the logamediate and intermediate forms of scale factors. The natures of statefinder and slow-roll parameters are discussed diagrammatically.

scholarly journals Anisotropic Universe with Manimally Interacting Matter and Holographic Dark Energy

2021 ◽  
Vol 42 (1) ◽  
pp. 39-57
Author(s):  
Mohammad Moksud Alam
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
State Parameter ◽  
Anisotropic Universe ◽  
Tensor Theory ◽  
Exponential Expansion ◽  
Recent Phase ◽  
Theory Of Gravitation ◽  
Expansion Model ◽  
The Universe

The holographic dark energy (HDE), a form of dark energy, has been a useful tool in explaining the recent phase transition of the universe. In this paper, we study the anisotropic and homogeneous Bianchi type-III model of the universe filled with minimally interacting matter and holographic dark energy under the framework of the Brans-Dicke (BD) scalar tensor theory of gravitation. Considering two physically plausible conditions such as, (i) the special law of variation for Hubble parameter and (ii) the scalar expansion proportional to the shear scalar, we propose two new models namely, exponential expansion model and power law expansion model. We also show the dynamics of these models fit with existing observational data and literature thereof. The transit behavior of the equation of state parameter for dark energy has been analyzed graphically. The jerk parameter is also studied for both of the models describing cosmological evolution. The Chittagong Univ. J. Sci. 42(1): 39-57, 2020

scholarly journals Axially magnetized dark energy cosmological model

2019 ◽  
Vol 34 (27) ◽  
pp. 1950217 ◽  
Author(s):  
B. Mishra ◽  
Pratik P. Ray ◽  
S. K. Tripathy ◽  
Kazuharu Bamba
Keyword(s):  
Magnetic Field ◽  
General Relativity ◽  
Dark Energy ◽  
State Parameter ◽  
Substantial Effect ◽  
Anisotropic Universe ◽  
Time Varying ◽  
Big Rip ◽  
Equation Of State Parameter ◽  
The Universe

We investigate the behavior of the skewness parameters for an anisotropic universe in the framework of General Relativity. Non-interacting dark energy is considered in presence of electromagnetic field. A time-varying deceleration parameter simulated by a hybrid scale factor is considered. The dynamics of the universe is investigated in presence and absence of magnetic field. The equation of state parameter of dark energy evolves within the range predicted by the observations. Magnetic field is observed to have a substantial effect on the cosmic dynamics and the skewness parameters. The models discussed here end in a big rip and become isotropic at finite time.

scholarly journals Dynamical Properties of Dark Energy Models in Fractal Universe

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1174
Author(s):  
Muhammad Umair Shahzad ◽  
Ayesha Iqbal ◽  
Abdul Jawad
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Accelerating Universe ◽  
Statefinder Parameters ◽  
Om Diagnostic ◽  
Energy Models ◽  
Expansion Of The Universe ◽  
Dynamical Properties ◽  
The Universe

In this paper, we consider the flat FRW spacetime filled with interacting dark energy and dark matter in fractal universe. We work with the three models of dark energy named as Tsallis, Renyi and Sharma–Mittal. We investigate different cosmological implications such as equation of state parameter, squared speed of sound, deceleration parameter, statefinder parameters, ω e f f - ω e f f ´ (where prime indicates the derivative with respect to ln a , and a is cosmic scale factor) plane and Om diagnostic. We explore these parameters graphically to study the evolving universe. We compare the consistency of dark energy models with the accelerating universe observational data. All three models are stable in fractal universe and support accelerated expansion of the universe.

scholarly journals ACCELERATING DARK ENERGY MODELS IN BIANCHI TYPE-V SPACETIME

2011 ◽  
Vol 26 (30) ◽  
pp. 2261-2275 ◽  
Author(s):  
ANIRUDH PRADHAN ◽  
HASSAN AMIRHASHCHI
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Late Time ◽  
Field Equations ◽  
Future Evolution ◽  
New Exact Solutions ◽  
Spatially Homogeneous ◽  
Type V ◽  
The Universe ◽  
Bianchi Type V

Some new exact solutions of Einstein's field equations in a spatially homogeneous and anisotropic Bianchi type-V spacetime with minimally interaction of perfect fluid and dark energy components have been obtained. To prevail the deterministic solution we choose the scale factor [Formula: see text], which yields a time-dependent deceleration parameter (DP), representing a model which generates a transition of the universe from the early decelerating phase to the recent accelerating phase. We find that for n ≥ 1, the quintessence model is reproducible with present and expected future evolution of the universe. The other models (for n < 1), we observe the phantom scenario. The quintessence as well as phantom models approach to isotropy at late time. For different values of n, we can generate a class of physically viable DE models. The cosmic jerk parameter in our descended model is also found to be in good concordance with the recent data of astrophysical observations under appropriate condition. The physical and geometric properties of spatially homogeneous and anisotropic cosmological models are discussed.

scholarly journals Bianchi type-V cosmology with magnetized anisotropic dark energy

2017 ◽  
Vol 95 (3) ◽  
pp. 274-282
Author(s):  
M. Farasat Shamir ◽  
Asad Ali
Keyword(s):  
Magnetic Field ◽  
Dark Energy ◽  
Bianchi Type ◽  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Anisotropic Universe ◽  
Field Equations ◽  
Constant Deceleration Parameter ◽  
Type V ◽  
Bianchi Type V

We study anisotropic universe in the presence of magnetized dark energy. Bianchi type-V cosmological model is considered for this purpose. The energy–momentum tensor consists of anisotropic fluid with uniform magnetic field of energy density ρB. Exact solutions to the field equations are obtained without using conventional assumptions like constant deceleration parameter. In particular, a general solution is obtained that further provides different classes of solutions. Only three cases have been discussed for the present analysis: linear, quadratic, and exponential. Graphical analyses of the solutions are done for all the three classes. The behavior of the model using some important physical parameters is discussed in the presence of magnetic field.

Anisotropic universe and generalized ghost dark energy in Brans–Dicke theory

2016 ◽  
Vol 94 (2) ◽  
pp. 201-208 ◽  
Author(s):  
V. Fayaz ◽  
H. Hossienkhani ◽  
A. Pasqua ◽  
Z. Zarei ◽  
M. Ganji
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Anisotropic Universe ◽  
Type I ◽  
De Sitter ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Ghost Dark Energy ◽  
The Stability ◽  
Generalized Ghost Dark Energy

In this paper, we consider the generalized ghost dark energy in a Bianchi type-I metric (which is a spatially homogeneous and anisotropic) in the framework of Brans–Dicke theory. For this purpose, we use the squared sound speed [Formula: see text] the sign of which determines the stability of the model. At first, we obtain the equation of state parameter, ωΛ = pΛ/ρΛ, the deceleration parameter q and the evolution equation of the generalized ghost dark energy. We find that, in this case, ωΛ cannot cross the phantom line (ωΛ > –1) and eventually the universe approaches a de-Sitter phase of expansion (ωΛ → –1). Then, we extend our study to the case of generalized ghost dark energy in a non-isotropic and Brans–Dicke framework and find out that the transition of ωΛ to the phantom regime can be more easily accounted for than when it is restored into the Einstein field equations. In conclusion, we find evidence that the generalized ghost dark energy in BD theory can lead to a stable universe favored by observations at the present time.

ANISOTROPIC UNIVERSE WITH HESSENCE DARK ENERGY

2010 ◽  
Vol 19 (13) ◽  
pp. 2071-2078 ◽  
Author(s):  
SHUVENDU CHAKRABORTY ◽  
UJJAL DEBNATH
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Anisotropic Universe ◽  
Field Equations ◽  
Complex Scalar ◽  
New Approach ◽  
Bianchi I ◽  
Scale Factors ◽  
Complex Scalar Field

In this work, we have considered a noncanonical complex scalar field named hessence to play the role of quintom in anisotropic universe (particularly in the Bianchi I model) as a new approach to look into the unknown mysterious world of dark energy. We have solved the field equations by considering the power-law form of scale factors and found the potential function in terms of ϕ with some restrictions. We also show here that hessence can avoid the Q-ball formation in anisotropic universe.

Accelerating universe with the effect of anisotropy on dark energy model in the framework of Brans–Dicke theory

2020 ◽  
Vol 17 (13) ◽  
pp. 2050194
Author(s):  
H. Hossienkhani ◽  
N. Azimi ◽  
Z. Zarei
Keyword(s):  
Dark Energy Model ◽  
State Parameter ◽  
Acoustic Oscillation ◽  
Accelerating Universe ◽  
Anisotropic Universe ◽  
Text Data ◽  
Type Ia ◽  
Best Fitting ◽  
Ia Supernovae ◽  
The Universe

This study set out to investigate the effect of anisotropy on the [Formula: see text]CDM model in the framework of Brans−Dicke theory. To this end, astrophysical constraints on this model using current available data including type Ia supernovae (SNIa), the Baryon Acoustic Oscillation (BAO), and the Hubble parameter [Formula: see text] data were deployed. Here, we present combined results from these probes, deriving constraints on [Formula: see text] of [Formula: see text]CDM model and its anisotropy energy density in an anisotropic universe. It is found that [Formula: see text] can be constrained by the [Formula: see text] data, with the best fitting value [Formula: see text] for the Brans–Dicke cosmology. We extend our study to the case of [Formula: see text]CDM model in an anisotropic universe and Brans–Dicke framework and find out that the equation of state parameter ([Formula: see text]) cannot cross the phantom line and eventually the universe approaches a quintessence era.

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