scholarly journals Holographic dark energy and the universe expansion acceleration

2006 ◽  
Vol 636 (2) ◽  
pp. 75-79 ◽  
Author(s):  
J.P. Beltrán Almeida ◽  
J.G. Pereira
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Universe Expansion ◽  
The Universe

scholarly journals Physical Acceptability of the Renyi, Tsallis and Sharma-Mittal Holographic Dark Energy Models in the f(T,B) Gravity under Hubble’s Cutoff

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 67
Author(s):  
Salim Harun Shekh ◽  
Pedro H. R. S. Moraes ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Field Equations ◽  
Eos Parameter ◽  
Two Fluids ◽  
Gravitational Field Equations ◽  
Energy Models ◽  
Different Types ◽  
The Universe

In the present article, we investigate the physical acceptability of the spatially homogeneous and isotropic Friedmann–Lemâitre–Robertson–Walker line element filled with two fluids, with the first being pressureless matter and the second being different types of holographic dark energy. This geometric and material content is considered within the gravitational field equations of the f(T,B) (where T is the torsion scalar and the B is the boundary term) gravity in Hubble’s cut-off. The cosmological parameters, such as the Equation of State (EoS) parameter, during the cosmic evolution, are calculated. The models are stable throughout the universe expansion. The region in which the model is presented is dependent on the real parameter δ of holographic dark energies. For all δ≥4.5, the models vary from ΛCDM era to the quintessence era.

scholarly journals PRESENT ACCELERATION OF THE UNIVERSE, HOLOGRAPHIC ENERGY AND BRANS–DICKE THEORY

2009 ◽  
Vol 24 (22) ◽  
pp. 1785-1792 ◽  
Author(s):  
B. NAYAK ◽  
L. P. SINGH
Keyword(s):  
Dark Energy ◽  
Power Law ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Accelerated Expansion ◽  
Temporal Behavior ◽  
Holographic Dark Energy Model ◽  
Acceleration Of The Universe ◽  
Expansion Of The Universe ◽  
The Universe

The present-day accelerated expansion of the universe is naturally addressed within the Brans–Dicke theory just by using holographic dark energy model with inverse of Hubble scale as IR cutoff and power law temporal behavior of scale factor. It is also concluded that if the universe continues to expand, then one day it might be completely filled with dark energy.

ENTROPY CORRECTED HOLOGRAPHIC DARK ENERGY f(T) GRAVITY MODEL

2014 ◽  
Vol 29 (02) ◽  
pp. 1450015 ◽  
Author(s):  
M. SHARIF ◽  
SHAMAILA RANI
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Phase Plane ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Accelerated Expansion ◽  
Statefinder Parameters ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Evolution Trajectory

This paper is devoted to study the power-law entropy corrected holographic dark energy (ECHDE) model in the framework of f(T) gravity. We assume infrared (IR) cutoff in terms of Granda–Oliveros (GO) length and discuss the constructed f(T) model in interacting as well as in non-interacting scenarios. We explore some cosmological parameters like equation of state (EoS), deceleration, statefinder parameters as well as ωT–ωT′ analysis. The EoS and deceleration parameters indicate phantom behavior of the accelerated expansion of the universe. It is mentioned here that statefinder trajectories represent consistent results with ΛCDM limit, while evolution trajectory of ωT–ωT′ phase plane does not approach to ΛCDM limit for both interacting and non-interacting cases.

scholarly journals DARK ENERGY: A UNIFYING VIEW

2008 ◽  
Vol 17 (03n04) ◽  
pp. 651-658 ◽  
Author(s):  
WINFRIED ZIMDAHL
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Interaction Strength ◽  
Chaplygin Gas ◽  
Accelerated Expansion ◽  
Strength Parameter ◽  
Expansion Of The Universe ◽  
Pressure Perturbations ◽  
The Universe

Different models of the cosmic substratum which pretend to describe the present stage of accelerated expansion of the Universe, like the ΛCDM model or the Chaplygin gas, can be seen as special realizations of a holographic dark energy cosmology if the option of an interaction between pressureless dark matter and dark energy is taken seriously. The corresponding interaction strength parameter plays the role of a cosmological constant. Differences occur at the perturbative level. In particular, the pressure perturbations are intrinsically nonadiabatic.

scholarly journals The Constant of the Universe Expansion Acceleration ΓH, the Einstein Variation of c and Parameters VH, Ω, Ʌ and ɣ

2020 ◽  
Vol 12 (3) ◽  
pp. 28
Author(s):  
J. G. Lartigue
Keyword(s):  
Dark Energy ◽  
Gravitational Field ◽  
Additional Condition ◽  
Expansion Velocity ◽  
Gravitational Acceleration ◽  
Universe Expansion ◽  
Physical Universe ◽  
C Value ◽  
Space Expansion ◽  
The Universe

The Hubble-Lemaitre equation v=H∙r  (cm∙s-1) represented a linear function of the radial Space expansion velocity, if H would be a constant. Sometimes it has been assumed as H = 1/t, which sends back to the classical v = r/t. However, the later discovered acceleration required the additional condition for H to be, also, a function of time; or, opposed, the existence of a not yet defined dark energy. In a previous paper [1] it had been proposed a provisional expression for a constant Universe expansion acceleration as function of distance: Γ= H2( cm∙s-2). Now, the substitution of r as a function of time, takes to five new equations of H, the Hubble velocity vH , the Hubble acceleration ΓH and the positive Hubble potential VH of the Space. So the proposed Hubble functions for the Space: H, rH , vH, ΓH and VH result higher than those in a gravitational field. All of these Hubble functions act in the total Space expansion though, into the Physical Universe, ΓH is not perceived as it does, continuously, the opposed gravitational acceleration g. Otherwise, a revision is made of the Einstein equation for the c value as function of the gravitational potential φ. Additional proposals are made about the horizons definitions and parameters Ω, Ʌ and ɣ.

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

Swampland criteria and cosmological behavior of Tsallis holographic dark energy in Bianchi -III Universe

2020 ◽  
Vol 17 (07) ◽  
pp. 2050098 ◽  
Author(s):  
Umesh Kumar Sharma ◽  
Shikha Srivastava ◽  
A. Beesham
Keyword(s):  
Dark Energy ◽  
Deceleration Parameter ◽  
Holographic Dark Energy ◽  
Accelerating Universe ◽  
Accelerating Expansion ◽  
Bianchi Iii ◽  
Expansion Of The Universe ◽  
Hubble Horizon ◽  
The Universe ◽  
Universe Evolution

In this paper, a new form of dark energy, known as Tsallis holographic dark energy (THDE), with IR cutoff as Hubble horizon proposed by Tavayef et al. Tsallis holographic dark energy, Phys. Lett. B 781 (2018) 195 has been explored in Bianchi-III model with the matter. By taking the time subordinate deceleration parameter, the solution of Einstein’s field equation is found. The Universe evolution from earlier decelerated to the current accelerated phase is exhibited by the deceleration parameter acquired in the THDE model. It can be seen that the derived THDE model is related to an accelerating Universe with quintessence ([Formula: see text]). The squared sound speed [Formula: see text] also suggests that the THDE model is classically stable at present. In addition, the quintessence phase of the THDE model is analyzed with swampland conjecture to reformulate the accelerating expansion of the Universe.

Reconstructing Tsallis holographic quintessence

2021 ◽  
Author(s):  
Umesh Kumar Sharma ◽  
Vandna Srivastava
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Quantum Gravity ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Energy Model ◽  
Holographic Dark Energy Model ◽  
The Universe ◽  
Modified Entropy

Within the framework of quantum gravity and modified entropy-area formalism, the Tsallis holographic dark energy is an effort to peep into a mysterious content of the Universe, the dark energy, to analyze its nature. The Tsallis parameter [Formula: see text] provides the main characteristic of the Tsallis holographic dark energy. Opting the value of Tsallis parameter [Formula: see text], a quintessence scalar field description of the Tsallis holographic dark energy model can be obtained. In this work, we present this quintessential explanation of the Tsallis holographic dark energy with [Formula: see text] and reconstruct the dynamics of the scalar field and the potential of quintessence.

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 Cosmological evolution with interaction between dark energy and dark matter

2015 ◽  
Vol 24 (03) ◽  
pp. 1530007 ◽  
Author(s):  
Yuri L. Bolotin ◽  
Alexander Kostenko ◽  
Oleg A. Lemets ◽  
Danylo A. Yerokhin
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Holographic Dark Energy ◽  
Main Task ◽  
Nonlinear Interactions ◽  
Dark Sector ◽  
Standard Cosmological Model ◽  
Linear And Nonlinear ◽  
The Universe

In this review we consider in detail different theoretical topics associated with interaction in the dark sector. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities. We consider a number of different models (including the holographic dark energy and dark energy in a fractal universe), with interacting dark energy and dark matter, have done a thorough analysis of these models. The main task of this review was not only to give an idea about the modern set of different models of dark energy, but to show how much can be diverse dynamics of the universe in these models. We find that the dynamics of a universe that contains interaction in the dark sector can differ significantly from the Standard Cosmological Model.

Sign in / Sign up

Export Citation Format

Share Document