scholarly journals Analysis of Bianchi Type V Holographic Dark Energy Models in General Relativity and Lyra’s Geometry

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Daba Meshesha Gusu ◽  
M. Vijaya Santhi
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Bianchi Type ◽  
Holographic Dark Energy ◽  
Holographic Dark Energy Model ◽  
Expansion Scalar ◽  
Lyra’S Geometry ◽  
Type V

In this paper, we analyze anisotropic and homogeneous Bianchi type V spacetime in the presence of dark matter and holographic dark energy model components in the framework of general relativity and Lyra’s geometry. The solutions of differential equation fields have been obtained by considering two specific cases, namely, the expansion scalar θ in the model is proportional to the shear scalar σ and the average scale factor taken as hybrid expansion form. The solutions for field equations are obtained in general relativity and Lyra’s geometry. The energy density of dark matter in both natures was obtained and compared so that the energy density of dark matter in general relativity is slightly different from the energy density of dark matter in Lyra’s geometry. A similar behavior occurred in case of pressure and EoS parameter of holographic dark energy model in respective frameworks. Also, it is concluded that the physical parameters such as the average Hubble parameter, spatial volume, anisotropy parameter, expansion scalar, and shear scalar are the same in both frameworks. Moreover, it is observed that the gauge function β t is a decreasing function of cosmic time in Lyra’s geometry, and for late times, the gauge function β t converges to zero and Lyra’s geometry reduces to general relativity in all respects. Finally, we conclude that our models are a close resemblance to the Λ CDM cosmological model in late times and consistent with the recent observations of cosmological data.

scholarly journals Holographic Dark Energy and Dark Matter Interaction in Anisotropic Bianchi Type-V Universe

2021 ◽  
pp. 19-31
Author(s):  
D. Gemici-Deveci ◽  
E. Aydiner
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Bianchi Type ◽  
Numerical Solutions ◽  
Holographic Dark Energy ◽  
Stretched Exponential ◽  
Bianchi Type V Universe ◽  
Type V ◽  
The Universe ◽  
Bianchi Type V

In this study, we consider an holographic dark energy and dark matter interacting model in the Bianchi Type-V universe with a stretched exponential scale factor. We obtain the Hubble, shear, deceleration, and equation of state parameters based on the presented model and give the numerical solutions. We show that the anisotropy in the early universe plays an important role in the time evolution of the universe. Furthermore, we show that an interacting anisotropic model with stretched exponential scale factors can explain all epochs of the universe.

scholarly journals HOLOGRAPHIC DARK ENERGY MODEL CHARACTERIZED BY THE CONFORMAL-AGE-LIKE LENGTH

2012 ◽  
Vol 27 (16) ◽  
pp. 1250085 ◽  
Author(s):  
ZHUO-PENG HUANG ◽  
YUE-LIANG WU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Dimensional Space ◽  
Early Time ◽  
Energy Model ◽  
Holographic Dark Energy Model ◽  
Frw Universe

A holographic dark energy model characterized by the conformal-age-like length scale [Formula: see text] is motivated from the four-dimensional space–time volume at cosmic time t in the flat Friedmann–Robertson–Walker (FRW) universe. It is shown that when the background constituent with constant equation of state wm dominates the universe in the early time, the fractional energy density of the dark energy scales as [Formula: see text] with the equation of state given by [Formula: see text]. The value of wm is taken to be wm≃-1 during inflation, wm = ⅓ in radiation-dominated epoch and wm = 0 in matter-dominated epoch, respectively. When the model parameter d takes the normal value at order one, the fractional density of dark energy is naturally negligible in the early universe, Ω de ≪1 at a ≪1. With such an analytic feature, the model can be regarded as a single-parameter model like the ΛCDM model, so that the present fractional energy density Ω de (a = 1) can solely be determined by solving the differential equation of Ωde once d is given. We further extend the model to the general case in which both matter and radiation are present. The scenario involving possible interaction between the dark energy and the background constituent is also discussed.

scholarly journals COSMOLOGICAL CONSTRAINT AND ANALYSIS ON HOLOGRAPHIC DARK ENERGY MODEL CHARACTERIZED BY THE CONFORMAL-AGE-LIKE LENGTH

2012 ◽  
Vol 27 (22) ◽  
pp. 1250130 ◽  
Author(s):  
ZHUO-PENG HUANG ◽  
YUE-LIANG WU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Energy Model ◽  
Single Parameter ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Holographic Dark Energy Model ◽  
Λcdm Model

We present a best-fit analysis on the single-parameter holographic dark energy model characterized by the conformal-age-like length, [Formula: see text]. Based on the Union2 compilation of 557 supernova Ia (SNIa) data, the baryon acoustic oscillation (BAO) results from the Sloan Digital Sky Survey data release 7 (SDSS DR7) and the cosmic microwave background radiation (CMB) data from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7), we show that the model gives the minimal [Formula: see text], which is comparable to [Formula: see text] for the ΛCDM model. The single parameter d concerned in the model is found to be d = 0.232±0.006±0.009. Since the fractional density of dark energy Ωde~ d2a2at a ≪ 1, the fraction of dark energy is naturally negligible in the early universe, Ωde≪ 1 at a ≪ 1. The resulting constraints on the present fractional energy density of matter and the equation of state are [Formula: see text] and [Formula: see text] respectively. We also provide a systematic analysis on the cosmic evolutions of the fractional energy density of dark energy, the equation of state of dark energy, the deceleration parameter and the statefinder. It is noticed that the equation of state crosses from wde> -1 to wde< -1, the universe transits from decelerated expansion (q > 0) to accelerated expansion (q < 0) recently, and the statefinder may serve as a sensitive diagnostic to distinguish the CHDE model with the ΛCDM model.

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