scholarly journals Holographic dark energy with the sign-changeable interaction term

2017 ◽  
Vol 26 (08) ◽  
pp. 1750080 ◽  
Author(s):  
M. Abdollahi Zadeh ◽  
A. Sheykhi ◽  
H. Moradpour
Keyword(s):  
Dark Energy ◽  
Event Horizon ◽  
Holographic Dark Energy ◽  
Late Time ◽  
Coupling Constant ◽  
Future Event ◽  
Frw Universe ◽  
Eos Parameter ◽  
The Future ◽  
Future Event Horizon

We use three infrared (IR) cutoffs, including the future event horizon, the Hubble and Granda–Oliveros (GO) cutoffs, to construct three holographic models of dark energy (DE). Additionally, we consider a Friedmann–Robertson–Walker (FRW) universe filled by a dark matter (DM) and a DE that interact with each other through a mutual sign-changeable interaction with positive coupling constant. Thereinafter, we address the evolution of the some cosmological parameters, such as the equation of state (EoS) and dimensionless density parameters of DE as well as the deceleration parameter, during the cosmic evolution from the matter-dominated era until the late-time acceleration. We observe that a holographic dark energy (HDE) model with Hubble cutoff interacting with DM cannot be in line with the current universe. Our study shows that models with the future event horizon as the IR cutoff or the GO cutoff are in good agreement with the observational data. In fact, we find out that these two recent models can predict the universe transition from a deceleration phase to the acceleration one in a compatible way with observations. The three obtained models may also allow the EoS parameter to cross the phantom line, a result which depends on the values of the system’s constants such as the value of the interaction coupling constant.

scholarly journals Sign-changeable holographic dark energy in Brans–Dicke theory

2019 ◽  
Vol 97 (7) ◽  
pp. 726-734 ◽  
Author(s):  
M. Abdollahi Zadeh ◽  
A. Sheykhi
Keyword(s):  
Dark Energy ◽  
Event Horizon ◽  
Holographic Dark Energy ◽  
Model Parameters ◽  
Density Parameter ◽  
Future Event ◽  
Frw Universe ◽  
Eos Parameter ◽  
The Stability ◽  
Future Event Horizon

We consider the Brans–Dicke (BD) theory of gravity and explore the cosmological implications of the sign-changeable interacting holographic dark energy (HDE) model in the background of a Friedmann–Robertson–Walker (FRW) universe. As the system’s infrared cutoff, we choose the future event horizon, the Granda–Oliveros (GO), and the Ricci cutoffs. For each cutoff, we obtain the density parameter, the equation of state (EoS), and the deceleration parameter of the system. In case of future event horizon, we find out that the EoS parameter, wD, can cross the phantom line; as a result the transition from the deceleration to the acceleration of the Universe expansion can be achieved provided the model parameters are chosen suitably. We also investigate the instability of the sign-changeable interacting HDE model against perturbations in BD theory. For this purpose, we study the squared sound speed [Formula: see text] whose sign determines the stability of the model. When [Formula: see text] the model is unstable against perturbation. For future event horizon, our Universe can be stable ([Formula: see text]) depending on the model parameters. Then, we focus on GO and Ricci cutoffs and find out that although other features of these two cutoffs are consistent with observations, they cannot lead to stable dominated universe, except in a special case with GO cutoff. Our studies confirm that for the sign-changeable HDE model in the setup of BD cosmology, the event horizon is the most suitable horizon that can pass all conditions and leads to a stable dark-energy-dominated universe.

scholarly journals Interacting holographic dark energy model in Brans–Dicke cosmology and coincidence problem

2018 ◽  
Vol 27 (03) ◽  
pp. 1850017 ◽  
Author(s):  
F. Felegary ◽  
F. Darabi ◽  
M. R. Setare
Keyword(s):  
Dark Energy ◽  
Event Horizon ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Holographic Dark Energy Model ◽  
Future Event ◽  
Coincidence Problem ◽  
The Future ◽  
Hubble Horizon ◽  
Future Event Horizon

We study the dynamics of interacting holographic dark energy model in Brans–Dicke cosmology for the future event horizon and the Hubble horizon cut-offs. We determine the system of first-order differential equations for the future event horizon and Hubble horizon cut-offs and obtain the corresponding fixed points, attractors, repellers and saddle points. Finally, we investigate the cosmic coincidence problem in this model for the future event horizon and Hubble horizon cut-offs and find that for both cut-offs and for a variety of Brans–Dicke parameters, the coincidence problem is almost resolved.

scholarly journals (m, n)-TYPE HOLOGRAPHIC DARK ENERGY MODELS

2013 ◽  
Vol 28 (31) ◽  
pp. 1350128 ◽  
Author(s):  
YI LING ◽  
WEN-JIAN PAN
Keyword(s):  
Dark Energy ◽  
Event Horizon ◽  
Holographic Dark Energy ◽  
Characteristic Size ◽  
Scalar Perturbation ◽  
Future Event ◽  
Energy Models ◽  
The Stability ◽  
Phantom Phase ◽  
Future Event Horizon

We construct (m, n)-type holographic dark energy models at a phenomenological level, which can be viewed as a generalization of agegraphic models with the conformal-like age as the holographic characteristic size. For some values of (m, n) the holographic dark energy can automatically evolve across ω = -1 into a phantom phase even without introducing an interaction between the dark energy and background matter. Our construction is also applicable to the holographic dark energy with generalized future event horizon as the characteristic size. Finally, we address the issue on the stability of our model and show that they are generally stable under the scalar perturbation.

scholarly journals Best values of parameters for interacting HDE with GO IR-cutoff in Brans–Dicke cosmology

2014 ◽  
Vol 23 (10) ◽  
pp. 1450081 ◽  
Author(s):  
A. Khodam-Mohammadi ◽  
E. Karimkhani ◽  
A. Sheykhi
Keyword(s):  
Dark Energy ◽  
Deceleration Parameter ◽  
Holographic Dark Energy ◽  
Late Time ◽  
Acceleration Phase ◽  
Coincidence Problem ◽  
Frw Universe ◽  
Eos Parameter ◽  
Phantom Divide ◽  
Friedmann Robertson Walker

We investigate the interacting holographic dark energy (HDE) with Granda–Oliveros (GO) infrared (IR)-cutoff in the framework of Brans–Dicke (BD) cosmology. We obtain the equation of state (EoS) parameter of HDE, wD, the effective EoS parameter w eff , the deceleration parameter q and the squared of sound speed [Formula: see text] in a flat Friedmann–Robertson–Walker (FRW) universe. We show that at late-time the cosmic coincidence problem can be alleviated. Also we show that for noninteracting case, HDE can give a unified dark matter–dark energy (DM–DE) profile in BD cosmology, except that it cannot solve the coincidence problem in the future. By studying the EoS parameter, we see that the phantom divide may be crossed. Using the latest observational data, we calculate the best values of the parameters for interacting HDE in BD framework. Computing the deceleration parameter implies that the transition from deceleration to the acceleration phase occurred for redshift z ≥ 0.5. Finally, we investigate the sound stability of the model, and find that HDE with Granda–Oliveros (GO)-cutoff in the framework of BD cosmology can lead to a stable DE-dominated universe favored by observations, provided we take β = 0.44 and b2 < 0.35. This is in contrast to HDE model in Einstein gravity which does not lead to a stable DE-dominated universe.

scholarly journals Interacting Rényi holographic dark energy with parametrization on the interaction term

2021 ◽  
Author(s):  
Umesh Kumar Sharma ◽  
Vipin Chandra Dubey
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Accelerated Expansion ◽  
Model Parameters ◽  
Density Parameter ◽  
Late Time ◽  
Frw Universe ◽  
Eos Parameter ◽  
Interaction Term

In this work, we study the Rényi holographic dark energy (RHDE) model in a flat FRW Universe where the infrared cut-off is taken care by the Hubble horizon and also by taking three different parametrizations of the interaction term between the dark matter and the dark energy. Analyzing graphically, the behavior of some cosmological parameters in particular deceleration parameter, equation of state (EoS) parameter, energy density parameter and squared speed of sound, in the process of the cosmic evolution, is found to be leading towards the late-time accelerated expansion of the RHDE model. Also, we find the departure for the derived models from the standard [Formula: see text]CDM model according to the evolution of jerk parameter. Moreover, we compare the model parameters by considering the observational Hubble data which consist of 51 points in the redshift range [Formula: see text].

scholarly journals Cosmology of Barrow Holographic Dark Energy as Nojiri-Odintsov Holographic Dark Energy with Specific Cut-off and the Thermodynamics

2021 ◽  
Author(s):  
Gargee Chakraborty ◽  
Surajit Chattopadhyay ◽  
Ertan Güdekli ◽  
Irina Radinschi
Keyword(s):  
Phase Transition ◽  
Dark Energy ◽  
Holographic Dark Energy ◽  
Second Law Of Thermodynamics ◽  
Electroweak Symmetry Breaking ◽  
Second Law ◽  
Late Time ◽  
Electroweak Symmetry ◽  
Eos Parameter ◽  
Reconstruction Scheme

Motivated by the work of Saridakis (Phys. Rev. D 102, 123525 (2020)), the present study reports the cosmological consequences of Barrow holographic dark energy (HDE) and its thermodynamics. Literatures demonstrate that Dark Energy (DE) may result from electroweak symmetry breaking that triggers a phase transition from early inflation to late time acceleration. In the present study, we incorporated viscosity in the Barrow HDE. A reconstruction scheme is presented for the parameters associated with Barrow holographic dark energy under the purview of viscous cosmology. Equation of state (EoS) parameter is reconstructed in this scenario and quintessence behaviour is observed. Considering BarrowHDE as a specific case ofNojiri-Odintsov (NO) HDE, we have observed quintom behaviour of the EoS parameter and for some values of n the EoS has been observed to be very close to &minus;1 for the current universe. The generalised second law of thermodynamics has come out to be valid in all the scenarios under consideration. Physical viability of considering Barrow HDE as a specific case of NO HDE is demonstrated in this study.

scholarly journals A dynamical system analysis of holographic dark energy models with different IR cutoff

2015 ◽  
Vol 30 (27) ◽  
pp. 1550134 ◽  
Author(s):  
Nilanjana Mahata ◽  
Subenoy Chakraborty
Keyword(s):  
Dynamical System ◽  
Dark Energy ◽  
System Analysis ◽  
Holographic Dark Energy ◽  
Holographic Model ◽  
Future Event ◽  
Dynamical Equations ◽  
Energy Models ◽  
Matter Energy ◽  
Future Event Horizon

The paper deals with a dynamical system analysis of the cosmological evolution of an holographic dark energy (HDE) model interacting with dark matter (DM) which is chosen in the form of dust. The infrared cutoff of the holographic model is considered as future event horizon or Ricci length scale. The interaction term between dark energy (DE) and DM is chosen of following three types: (i) proportional to the sum of the energy densities of the two dark components, (ii) proportional to the product of the matter energy densities and (iii) proportional to DE density. The dynamical equations are reduced to an autonomous system for the three cases and corresponding phase space is analyzed.

scholarly journals Thermodynamics of Barrow Holographic Dark Energy with Specific Cut-Off

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 562
Author(s):  
Gargee Chakraborty ◽  
Surajit Chattopadhyay ◽  
Ertan Güdekli ◽  
Irina Radinschi
Keyword(s):  
Phase Transition ◽  
Dark Energy ◽  
Holographic Dark Energy ◽  
Second Law Of Thermodynamics ◽  
Electroweak Symmetry Breaking ◽  
Second Law ◽  
Late Time ◽  
Electroweak Symmetry ◽  
Eos Parameter ◽  
Reconstruction Scheme

Motivated by the work of Saridakis (Phys. Rev. D102, 123525 (2020)), the present study reports the cosmological consequences of Barrow holographic dark energy (HDE) and its thermodynamics. The literature demonstrates that dark energy (DE) may result from electroweak symmetry breaking that triggers a phase transition from early inflation to late-time acceleration. In the present study, we incorporated viscosity in the Barrow HDE. A reconstruction scheme is presented for the parameters associated with Barrow holographic dark energy under the purview of viscous cosmology. The equation of state (EoS) parameter is reconstructed in this scenario and quintessence behaviour is observed. Considering Barrow HDE as a specific case of Nojiri–Odintsov (NO) HDE, we have observed quintom behaviour of the EoS parameter and for some values of n the EoS has been observed to be very close to −1 for the current universe. The generalised second law of thermodynamics has come out to be valid in all the scenarios under consideration. Physical viability of considering Barrow HDE as a specific case of NO HDE is demonstrated in this study. Finally, it has been observed that the model under consideration is very close to ΛCDM and cannot go beyond it.

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