scholarly journals SELF-INTERACTING HOLOGRAPHIC DARK ENERGY

2013 ◽  
Vol 28 (01) ◽  
pp. 1250235 ◽  
Author(s):  
LUIS P. CHIMENTO ◽  
MÓNICA FORTE ◽  
MARTÍN G. RICHARTE
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Statistical Method ◽  
Observational Data ◽  
Holographic Dark Energy ◽  
High Redshift ◽  
Distance Modulus ◽  
Coincidence Problem ◽  
Frw Universe ◽  
Friedmann Robertson Walker

We investigate a spatially flat Friedmann–Robertson–Walker (FRW) universe where dark matter exchanges energy with a self-interacting holographic dark energy (SIHDE). Using the χ2-statistical method on the Hubble function, we obtain a critical redshift that seems to be consistent with both BAO and CMB data. We calculate the theoretical distance modulus for confronting with the observational data of SNe Ia for small redshift z ≤ 0.1 and large redshift 0.1 ≤ z ≤ 1.5. The model gets accelerated faster than the ΛCDM one and it can be a good candidate to alleviate the coincidence problem. We also examine the age crisis at high redshift associated with the old quasar APM 08279+5255.

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 Holographic cosmology with two coupled fluids in the presence of viscosity

2021 ◽  
pp. 2150149
Author(s):  
I. Brevik ◽  
A. V. Timoshkin
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Holographic Dark Energy ◽  
Exponential Model ◽  
Point Of View ◽  
Accelerating Universe ◽  
Late Time ◽  
Conservation Of Energy ◽  
Analytical Expressions ◽  
Friedmann Robertson Walker

We explore the cosmological models of the late-time universe based on the holographic principle, taking into account the properties of the viscosity of the dark fluid. We use the mathematical formalism of generalized infrared cutoff holographic dark energy, as presented by Nojiri and Odintsov [Covariant generalized holographic dark energy and accelerating universe, Eur. Phys. J. C 77 (2017) 528]. We consider the Little Rip, the Pseudo Rip, and a bounce exponential model, with two interacting fluids, namely dark energy and dark matter in a spatially-flat Friedmann–Robertson–Walker universe. Within these models, analytical expressions are obtained for infrared cutoffs in terms of the particle horizons. The law of conservation of energy is presented, from a holographic point of view.

scholarly journals Statefinder and Om Diagnostics for New Generalized Chaplygin Gas Model

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 362
Author(s):  
Abdulla Al Mamon ◽  
Vipin Chandra Dubey ◽  
Kazuharu Bamba
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Observational Data ◽  
Hubble Parameter ◽  
Chaplygin Gas ◽  
Distance Modulus ◽  
Generalized Chaplygin Gas ◽  
New Model ◽  
Λcdm Model ◽  
Data Points

We explore a unified model of dark matter and dark energy. This new model is a generalization of the generalized Chaplygin gas model and is known as a new generalized Chaplygin gas (NGCG) model. We study the evolutions of the Hubble parameter and the distance modulus for the model under consideration and the standard ΛCDM model and compare that with the observational datasets. Furthermore, we demonstrate two geometric diagnostics analyses including the statefinder (r,s) and Om(z) to the discriminant NGCG model from the standard ΛCDM model. The trajectories of evolution for (r,s) and Om(z) diagnostic planes are shown to understand the geometrical behavior of the NGCG model by using different observational data points.

scholarly journals Tsallis Holographic Dark Energy with Granda-Oliveros Scale in (n+1)-Dimensional FRW Universe

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Ayman A. Aly
Keyword(s):  
Dark Energy ◽  
Speed Of Sound ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Holographic Dark Energy Model ◽  
Frw Universe ◽  
Accelerating Expansion ◽  
The Stability ◽  
The Universe ◽  
Friedmann Robertson Walker

Based on Tsallis holographic dark energy model recently proposed by using the general model of the Tsallis entropy expression, we reconstruct cosmographic parameters, q,j,κ,l, and we study their evolution in spatially flat (n+1)-dimensional Friedmann-Robertson-Walker universe using Granda-Oliveros scale. Our results show that the universe is in an accelerating expansion mode described by phantom-like behavior. We go further and study the state finder operators and the Om diagnostic to understand the behavior of our model. The stability of the system is also studied by using the square of speed of sound showing that our model is stable over the low range of red-shift considered. The results indicate that the entropy formalism will play an important role in understanding the dynamics of our universe.

scholarly journals An interacting new holographic dark energy model: Observational constraints

2019 ◽  
Vol 28 (12) ◽  
pp. 1950152 ◽  
Author(s):  
Ehsan Sadri ◽  
Martiros Khurshudyan
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Observational Data ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Current Model ◽  
Energy Model ◽  
Late Time ◽  
Holographic Dark Energy Model ◽  
Frw Universe

In this paper, we study an interacting new holographic dark energy model (NHDE) in DGP braneworld with a spatially flat FRW universe. Mainly, in this study we concentrate our attention on both interacting and noninteracting forms of the model. The study shows that the equation of state and the deceleration parameter depict an accelerated universe for all variety of interactions. On the other hand, the StateFinder analysis shows that the interacting and noninteracting behave similar to both quintessence and phantom dark energy and for the present value obey the behavior of quintessence. Moreover, the result of [Formula: see text]-diagnostic emphasizes on the result of the equation of state showing that the current model in high–[Formula: see text] stays in the quintessence era and in the late time has the Phantom-like behavior. By the use of the squared sound speed [Formula: see text] we find that the present mode has a good stability. In order to obtain the best fit values of the parameters in this work, we used the latest observational data (Pantheon, Boss DR12 and Planck 2015) implementing MCMC method by the use of EMCEE python package. We also employ AkaikeInformation Criterion (AIC) and Bayesian Information Criterion (BIC) model selection tools and comparethe model with both [Formula: see text]CDM and holographic Ricci dark energy as the reference models. We observe that the evidence against the interacting and noninteracting NHDE with consideration of both references is strongly positive and BIC rules out the NHDE model. Generally, the results of AIC and BIC state that the observational data do not favor the NHDE model.

scholarly journals THERMODYNAMICS OF INTERACTING ENTROPY-CORRECTED HOLOGRAPHIC DARK ENERGY IN A NON-FLAT FRW UNIVERSE

2010 ◽  
Vol 19 (11) ◽  
pp. 1831-1842 ◽  
Author(s):  
MUBASHER JAMIL ◽  
AHMAD SHEYKHI ◽  
M. UMAR FAROOQ
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Conservation ◽  
Quantum Cosmology ◽  
Holographic Dark Energy ◽  
Thermal Fluctuation ◽  
Quantum Corrections ◽  
Loop Quantum Cosmology ◽  
Frw Universe ◽  
Interaction Term

An entropy-corrected holographic dark energy (ECHDE) was recently proposed to explain the dark energy-dominated universe with the help of quantum corrections to the entropy–area relation in the setup of loop quantum cosmology. Using this new definition, we investigate its thermodynamical features including entropy and energy conservation. We describe the thermodynamical interpretation of the interaction between ECHDE and dark matter in a non-flat universe. We obtain a relation between the interaction term of the dark components and thermal fluctuation. Our study further generalizes the earlier works86, 87 in this direction.

scholarly journals A note on cosmological features of modified Newtonian potentials

2019 ◽  
Vol 34 (21) ◽  
pp. 1950168 ◽  
Author(s):  
M. Kord Zangeneh ◽  
H. Moradpour ◽  
N. Sadeghnezhad
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Total Energy ◽  
Spiral Galaxies ◽  
Test Mass ◽  
Frw Universe ◽  
Rotation Curves ◽  
Friedmann Equations ◽  
Friedmann Robertson Walker

Considering some modified Newtonian potentials and the Hubble law in writing the total energy of a test mass located at the edge of a flat Friedmann–Robertson–Walker (FRW) universe, we obtain several modified Friedmann equations. Interestingly enough, our study shows that the employed potentials, while some of them have some successes in modeling the spiral galaxies rotation curves, may also address an accelerated universe. This fact indicates that dark energy and dark matter may have some common origins and aspects.

scholarly journals Thermodynamic descriptions of polytropic gas and its viscous type as dark energy candidates

2016 ◽  
Vol 94 (3) ◽  
pp. 334-341 ◽  
Author(s):  
Hooman Moradpour ◽  
Mohammad-Taghi Mohammadi Sabet
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Correction Term ◽  
Thermal Fluctuation ◽  
Second Law Of Thermodynamics ◽  
Coincidence Problem ◽  
Frw Universe ◽  
Polytropic Gas ◽  
Horizon Entropy ◽  
Polytropic Equation

In this paper, at first, we focus on a Friedmann–Robertson–Walker (FRW) universe in which the dark energy candidate satisfies the polytropic equation of state and study thermodynamics of dark energy. Bearing the thermal fluctuation theorem in mind, we establish a relation between the thermal fluctuation of the system and mutual interaction between the dark energy and dark matter. Generalization to a viscous polytropic gas is also investigated. We point to a condition for decaying the dark energy candidate into the dark matter needed for alleviating the coincidence problem. The effects of dark energy candidates and their interactions with other parts of the cosmos on the horizon entropy as well as the second law of thermodynamics are also addressed. Our study suggests a correction term besides the Bekenstein entropy, which carries the information of the dark energy candidate, its interaction with other parts of the cosmos, and its viscosity.

scholarly journals INTERACTION BETWEEN DARK ENERGY AND DARK MATTER: OBSERVATIONAL CONSTRAINTS FROM OHD, BAO, CMB AND SNe Ia

2013 ◽  
Vol 22 (14) ◽  
pp. 1350082 ◽  
Author(s):  
SHUO CAO ◽  
NAN LIANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Observational Constraints ◽  
Coincidence Problem ◽  
Cosmological Constraints ◽  
Coincidence Index ◽  
Acceleration Of The Universe ◽  
Interaction Term ◽  
Negative Coupling ◽  
The Universe

In order to test if there is energy transfer between dark energy (DE) and dark matter (DM), we investigate cosmological constraints on two forms of nontrivial interaction between the DM sector and the sector responsible for the acceleration of the universe, in light of the newly revised observations including OHD, CMB, BAO and SNe Ia. More precisely, we find the same tendencies for both phenomenological forms of the interaction term Q = 3γHρ, i.e. the parameter γ to be a small number, |γ| ≈ 10-2. However, concerning the sign of the interaction parameter, we observe that γ > 0 when the interaction between dark sectors is proportional to the energy density of dust matter, whereas the negative coupling (γ < 0) is preferred by observations when the interaction term is proportional to DE density. We further discuss two possible explanations to this incompatibility and apply a quantitative criteria to judge the severity of the coincidence problem. Results suggest that the γm IDE model with a positive coupling may alleviate the coincidence problem, since its coincidence index C is smaller than that for the γd IDE model, the interacting quintessence and phantom models by four orders of magnitude.

scholarly journals Emergent Universe as an interaction in the dark sector

2017 ◽  
Vol 32 (28) ◽  
pp. 1750152
Author(s):  
Emiliano Marachlian ◽  
I. E. Sánchez G. ◽  
Osvaldo P. Santillán
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Linear Equation ◽  
Vacuum Energy ◽  
Cosmological Parameters ◽  
Emergent Universe ◽  
Dark Sector ◽  
Cosmological Scenario ◽  
Friedmann Robertson Walker

A cosmological scenario where dark matter interacts with a variable vacuum energy for a spatially flat Friedmann–Robertson–Walker (FRW) spacetime is proposed and analyzed to show that with a linear equation of state and a particular interaction in the dark sector it is possible to get a model of an Emergent Universe. In addition, the viability of two particular models is studied by taking into account the recent observations. The updated observational Hubble data and the JLA supernovae data are used in order to constraint the cosmological parameters of the models and estimate the amount of dark energy in the radiation era. It is shown that the two models fulfil the severe bounds of [Formula: see text] at the 2[Formula: see text] level of Planck.

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