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

Holographic dark energy model in Bianchi type VI0 Universe in a scalar–tensor theory of gravitation with hybrid expansion law

2016 ◽  
Vol 94 (12) ◽  
pp. 1338-1343 ◽  
Author(s):  
D.R.K. Reddy ◽  
S. Anitha ◽  
S. Umadevi
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Holographic Dark Energy ◽  
Space Time ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Tensor Theory ◽  
Theory Of Gravitation ◽  
The Universe ◽  
Energy Components

In this paper, we have obtained field equations of Sáez–Ballester (Phys. Lett. A, 113, 467 (1986)) scalar–tensor theory in the presence of two minimally interacting fields; matter and holographic dark energy components in the space–time described by a spatially homogeneous and anisotropic Bianchi type VI0 space–time. We have used the hybrid expansion law, proposed by Akarsu et al. (JCAP, 01, 022 (2014)), to obtain a determinate solution of the field equations. This solution represents a minimally interacting Bianchi type VI0 Sáez–Ballester universe. Physical and kinematical properties of the universe are also studied.

scholarly journals Bianchi type-III Tsallis holographic dark energy model in Saez–Ballester theory of gravitation

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
M. Vijaya Santhi ◽  
Y. Sobhanbabu
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Graphical Representation ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Field Equations ◽  
Om Diagnostic ◽  
Hubble Radius ◽  
Theory Of Gravitation

AbstractIn this paper, we have investigated Tsallis holographic dark energy (infrared cutoff is the Hubble radius) in homogeneous and anisotropic Bianchi type-III Universe within the framework of Saez–Ballester scalar–tensor theory of gravitation. We have constructed non-interaction and interaction dark energy models by solving the Saez–Ballester field equations. To solve the field equations, we assume a relationship between the metric potentials of the model. We developed the various cosmological parameters (namely deceleration parameter q, equation of state parameter $$\omega _t$$ ω t , squared sound speed $$v_s^2$$ v s 2 , om-diagnostic parameter Om(z) and scalar field $$\phi $$ ϕ ) and well-known cosmological planes (namely $$\omega _t-\omega _t^{'}$$ ω t - ω t ′ plane, where $$'$$ ′ denotes derivative with respect to ln(a) and statefinders ($$r-s$$ r - s ) plane) and analyzed their behavior through graphical representation for our both the models. It is also, quite interesting to mention here that the obtained results are coincide with the modern observational data.

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.

Viscous holographic f(Q) cosmology with some versions of holographic dark energy with generalized cut-offs

2022 ◽  
Vol 21 (12) ◽  
pp. 317
Author(s):  
Gargee Chakraborty ◽  
Surajit Chattopadhyay ◽  
Ertan Güdekli
Keyword(s):  
Dark Energy ◽  
Viscous Fluid ◽  
Holographic Dark Energy ◽  
Cosmic Time ◽  
Ricci Dark Energy ◽  
Slow Roll ◽  
Exponential Expansion ◽  
Viscous Pressure ◽  
The Universe ◽  
Increasing Functions

Abstract The work reported in this paper demonstrates the cosmology of f(Q) gravity and the reconstruction of various associated parameters with different versions of holographic dark energy with generalized cut-offs, where Q = 6 H 2. The Universe is considered to be filled with viscous fluid characterized by a viscous pressure Π = – 3 H ξ, where ξ = ξ 0 + ξ 1 H + ξ 2 ( H ˙ + H 2 ) and H is the Hubble parameter. Considering the power law form of expansion, we have derived the expression of f(Q) under a non-viscous holographic framework and it is then extended to viscous cosmological settings with extended generalized holographic Ricci dark energy. The forms of f(Q) for both the cases are found to be monotonically increasing functions of Q. In the viscous holographic framework, f(Q) is reconstructed as a function of cosmic time t and is found to stay at a positive level with Nojiri-Odintsov cut-off. In these cosmological settings, the slow roll parameters are computed and a scope of exit from inflation and quasi-exponential expansion are found to be available. Finally, it is observed that warm inflationary expansion can be obtained from this model.

scholarly journals Cosmic Evolution of Holographic Dark Energy in f(G,T) Gravity

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
M. Sharif ◽  
Ayesha Ikram
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Phase Plane ◽  
Holographic Dark Energy ◽  
State Parameter ◽  
Momentum Tensor ◽  
Chaplygin Gas ◽  
Cosmic Evolution ◽  
Evolutionary Trajectories ◽  
The Universe

The aim of this paper is to analyze the cosmological evolution of holographic dark energy in f(G,T) gravity (G and T represent the Gauss-Bonnet invariant and trace of the energy-momentum tensor, respectively). We reconstruct f(G,T) model through correspondence scheme using power-law form of the scale factor. The qualitative analysis of the derived model is investigated with the help of evolutionary trajectories of equation of state and deceleration as well as state-finder diagnostic parameters and ωGT-ωGT′ cosmological phase plane. It is found that the equation of state parameter represents phantom epoch of the Universe whereas the deceleration parameter illustrates the accelerated phase. The state-finder plane corresponds to Chaplygin gas model while the freezing region is attained in ωGT-ωGT′ plane.

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 Modified holographic energy density-driven inflation and some cosmological outcomes

2020 ◽  
Vol 17 (05) ◽  
pp. 2050066
Author(s):  
Gargee Chakraborty ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Bulk Viscosity ◽  
Holographic Dark Energy ◽  
State Parameter ◽  
Late Time ◽  
Effective Equation ◽  
Inflationary Scenario ◽  
Acceleration Of The Universe ◽  
The Universe

Motivated by the work of Nojiri et al. [S. Nojiri, S. D. Odintsov and E. N. Saridakis, Holographic inflation, Phys. Lett. B 797 (2019) 134829], this study reports a model of inflation under the consideration that the inflationary regime is originated by a type of holographic energy density. The infrared cutoff has been selected based on the modified holographic model that is a particular case of Nojiri–Odintsov holographic dark energy [S. Nojiri and S. D. Odintsov, Unifying phantom inflation with late-time acceleration: Scalar phantom–non-phantom transition model and generalized holographic dark energy, Gen. Relativ. Gravit. 38 (2006) 1285] that unifies phantom inflation with the acceleration of the universe on late time. On getting an analytical solution for Hubble parameter we considered the presence of bulk viscosity and the effective equation of state parameter appeared to be consistent with inflationary scenario with some constraints. It has also being observed that in the inflationary scenario the contribution of bulk viscosity is not of much significance and its influence is increasing with the evolution of the universe. Inflationary observables have been computed for the model and the slow-roll parameters have been computed. Finally, it has been observed that the trajectories in [Formula: see text] are compatible with the observational bound found by Planck. It has been concluded that the tensor to scalar ratio for this model can explain the primordial fluctuation in the early universe as well.

Tsallis holographic dark energy models in axially symmetric space time

2020 ◽  
Vol 17 (01) ◽  
pp. 2050011 ◽  
Author(s):  
Vipin Chandra Dubey ◽  
Ambuj Kumar Mishra ◽  
Shikha Srivastava ◽  
Umesh Kumar Sharma
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Holographic Dark Energy ◽  
Field Potential ◽  
Accelerated Expansion ◽  
Anisotropic Universe ◽  
Axially Symmetric ◽  
Eos Parameter ◽  
Quintessence Field ◽  
The Universe

In this work, we have examined the behavior of Bianchi-I (axially symmetric) matter-dominated and the anisotropic Universe with the proposed dark energy, Tsallis holographic dark energy (THDE), with the Hubble horizon as infrared cut-off [Tavayef et al., Tsallis holographic dark energy, Phys. Lett. B 781 (2018) 195–200]. The Universe evolution from matter-dominated epoch to dark energy dominated epoch is described by our proposed THDE model. The EoS parameter in our THDE model explains the evolution of the Universe according to the value of nonextensive or Tsallis parameter [Formula: see text], phantom era ([Formula: see text]) or quintom (phantom line crossing) and the quintessence era ([Formula: see text]), before reaching to completely dark energy-dominated era in the future. Additionally, we also plan to reconcile the dark energy by the method of reconstructing the evolution of the scalar field potential. For the analysis, we take into account the quintessence field and phantom scalar field for this reconstruction, which at present shows the accelerated expansion.

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