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19 pages, 507 KB

Open AccessArticle

Lagrangian Reconstruction of Barrow Holographic Dark Energy in Interacting Tachyon Model

by Giuseppe Gaetano Luciano and Yang Liu

Symmetry 2023, 15(5), 1129; https://doi.org/10.3390/sym15051129 - 22 May 2023

Cited by 18 | Viewed by 2100

We consider a correspondence between the tachyon dark energy model and Barrow holographic dark energy (BHDE). The latter is a modified scenario based on the application of the holographic principle with Barrow entropy instead of the usual Bekenstein–Hawking one. We reconstruct the dynamics of the tachyon scalar field T in a curved Friedmann–Robertson–Walker universe both in the presence and absence of interactions between dark energy and matter. As a result, we show that the tachyon field exhibits non-trivial dynamics. In a flat universe,

{\dot{T}}^{2}

must always be vanishing, independently of the existence of interaction. This implies

ω_{D} = - 1

for the equation-of-state parameter, which in turn can be used for modeling the cosmological constant behavior. On the other hand, for a non-flat universe and various values of the Barrow parameter, we find that

{\dot{T}}^{2}

decreases monotonically for increasing

cos (R_{h} / a)

and

cosh (R_{h} / a)

, where

R_{h}

and a are the future event horizon and the scale factor, respectively. Specifically,

{\dot{T}}^{2} \geq 0

for a closed universe, while

{\dot{T}}^{2} < 0

for an open one, which is physically not allowed. We finally comment on the inflation mechanism and trans-Planckian censorship conjecture in BHDE and discuss observational consistency of our model. Full article

(This article belongs to the Special Issue Noether Symmetries in Gravitation and Cosmology)

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12 pages, 505 KB

Open AccessArticle

Holographic Dark Energy in Modified Barrow Cosmology

by Ahmad Sheykhi and Maral Sahebi Hamedan

Entropy 2023, 25(4), 569; https://doi.org/10.3390/e25040569 - 26 Mar 2023

Cited by 19 | Viewed by 2871

Abstract

Thermodynamics–gravity conjecture implies that there is a deep connection between the gravitational field equations and the first law of thermodynamics. Therefore, any modification to the entropy expression directly modifies the field equations. By considering the modified Barrow entropy associated with the apparent horizon, the Friedmann equations are modified as well. In this paper, we reconsider the holographic dark energy (HDE) model when the entropy is in the form of Barrow entropy. This modification to the entropy not only changes the energy density of the HDE but also modifies the Friedmann equations. Therefore, one should take into account the modified HDE in the context of modified Friedmann equations. We study the Hubble horizon and the future event horizon as IR cutoffs and investigate the cosmological consequences of this model. We also extend our study to the case where dark matter (DM) and dark energy (DE) interact with each other. We observe that Barrow exponent

δ

significantly affects the cosmological behavior of HDE, and in particular, the equation of state (EoS) parameter can cross the phantom line

(w_{d e} < - 1)

. Additionally, adding

δ

remarkably affects the deceleration parameter and shifts the time of universe phase transition. Full article

(This article belongs to the Special Issue Geometrothermodynamics and Its Applications)

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16 pages, 569 KB

Open AccessArticle

Scalar Field Models of Barrow Holographic Dark Energy in f(R,T) Gravity

by Umesh Kumar Sharma, Mukesh Kumar and Gunjan Varshney

Universe 2022, 8(12), 642; https://doi.org/10.3390/universe8120642 - 2 Dec 2022

Cited by 16 | Viewed by 2391

Abstract

This research study investigates Barrow holographic dark energy with an energy density of

ρ_{Λ} = C H^{2 - Δ}

by considering the Hubble horizon as the IR cut-off in the

f (R, T)

gravity framework. We employ Barrow [...] Read more.

This research study investigates Barrow holographic dark energy with an energy density of

ρ_{Λ} = C H^{2 - Δ}

by considering the Hubble horizon as the IR cut-off in the

f (R, T)

gravity framework. We employ Barrow holographic dark energy to obtain the equation of the state for the Barrow holographic energy density in a flat FLRW Universe. Concretely, we study the correspondence between quintessence, k-essence, and dilation scalar field models with the Barrow holographic dark energy in a flat

f (R, T)

Universe. Furthermore, we reconstruct the dynamics and potential for all these models for different values of the Barrow parameter:

Δ

. Via this study, we can show that for Barrow holographic quintessence, k-essence, and dilation scalar field models, if the corresponding model parameters satisfy some limitations, the accelerated expansion can be achieved. Full article

(This article belongs to the Special Issue Dark Matter and Dark Energy: Particle Physics, Cosmology, and Experimental Searches)

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12 pages, 928 KB

Open AccessArticle

Phase Space Analysis of Barrow Agegraphic Dark Energy

by Hai Huang, Qihong Huang and Ruanjing Zhang

Universe 2022, 8(9), 467; https://doi.org/10.3390/universe8090467 - 7 Sep 2022

Cited by 10 | Viewed by 2167

Abstract

Using the Barrow entropy and considering the timescale as IR cutoff, a new holographic dark energy model named Barrow agegraphic dark energy (BADE) was proposed. We use phase space analysis method to discuss the evolution of the universe in three different mode of [...] Read more.

Q = 0

;

Q = 3 α H (ρ_{m} + ρ_{D})

;

Q = H (α ρ_{m} + β ρ_{D})

). We find the attractor which represents the dark energy-dominated era exists in all cases. In the case

Q = 0

and

Q = H (α ρ_{m} + β ρ_{D})

with

β = 0

, the attractor can behave as the cosmological constant, and these models can used to mimic the cosmological constant. Full article

(This article belongs to the Special Issue Dark Matter and Dark Energy: Particle Physics, Cosmology, and Experimental Searches)

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17 pages, 705 KB

Open AccessArticle

Braneworld Inspires Cosmological Implications of Barrow Holographic Dark Energy

by Shamaila Rani and Nadeem Azhar

Universe 2021, 7(8), 268; https://doi.org/10.3390/universe7080268 - 27 Jul 2021

Cited by 29 | Viewed by 3196

Abstract

In the present manuscript, the evolution of the cosmic parameters and planes are being investigated in the framework of the DGP braneworld model. In this scenario, the interaction

Γ

between the Barrow holographic dark energy model (whose infrared cutoff scale is set by [...] Read more.

In the present manuscript, the evolution of the cosmic parameters and planes are being investigated in the framework of the DGP braneworld model. In this scenario, the interaction

Γ

between the Barrow holographic dark energy model (whose infrared cutoff scale is set by Hubble and event horizons) and pressureless dark matter are considered. We check the behavior of different cosmological parameters such as Hubble, equation of state, deceleration and squared speed of sound from the early matter-dominated era until the late-time acceleration. It is found that the range of Hubble parameter lies in the interval

95_{- 35}^{+ 35}

(for Hubble horizon) and

97_{- 23}^{+ 23}

(for event horizon). For both horizons, the equation of state parameter favors the phantom dominant era as well as the

Λ

CDM model while the deceleration parameter illustrates the accelerated expansion of the universe. Furthermore, stability of the underlying model is found through squared speed of sound. Furthermore, it is observed that

ω - ω_{ϑ}^{'}

plane corresponds to freezing and thawing region for Hubble and event horizons, respectively. Furthermore, statefinder plane shows the

Λ

CDM and Chaplygin gas behavior for both models. Finally, we investigate the thermodynamical nature of the underlying model through Barrow entropy as horizon entropy and found validity for both horizons. Full article

(This article belongs to the Special Issue Cosmological Models, Quantum Theories and Astrophysical Observations)

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15 pages, 1262 KB

Open AccessEditor’s ChoiceArticle

Thermodynamics of Barrow Holographic Dark Energy with Specific Cut-Off

by Gargee Chakraborty, Surajit Chattopadhyay, Ertan Güdekli and Irina Radinschi

Symmetry 2021, 13(4), 562; https://doi.org/10.3390/sym13040562 - 29 Mar 2021

Cited by 53 | Viewed by 5680

Abstract

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

Λ

CDM and cannot go beyond it. Full article

(This article belongs to the Special Issue Symmetry: Feature Papers 2022)

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