scholarly journals Some models of holographic dark energy on the Randall–Sundrum brane and observational data

2019 ◽  
Vol 29 (01) ◽  
pp. 1950176 ◽  
Author(s):  
A. V. Astashenok ◽  
A. S. Tepliakov
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Observational Data ◽  
Energy Analysis ◽  
Holographic Dark Energy ◽  
Brane Tension ◽  
Dark Energy Density ◽  
Energy Models ◽  
Current Energy ◽  
The Universe

Some models of holographic dark energy for Randall–Sundrum brane are considered. For the first class of dark energy models, we take energy density in the form [Formula: see text], where [Formula: see text] is size of event horizon in universe and [Formula: see text] is parameter (Tsallis holographic energy). Analysis of observational data allows to define upper limit on value of [Formula: see text] ([Formula: see text] is current energy density in the universe and [Formula: see text] is brane tension). Then we investigate models for which dark energy density has the form [Formula: see text] where [Formula: see text] is Hubble parameter.

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.

Holographic dark energy in a vector field cosmology

2015 ◽  
Vol 12 (10) ◽  
pp. 1550119 ◽  
Author(s):  
S. Davood Sadatian
Keyword(s):  
Dark Energy ◽  
Vector Field ◽  
Equation Of State ◽  
Energy Density ◽  
Holographic Dark Energy ◽  
Lorentz Invariance ◽  
Holographic Model ◽  
Dark Energy Density ◽  
Invariance Violation ◽  
Lorentz Invariance Violation

We obtain interacting holographic dark energy density in the framework of vector field cosmology (LIV). We consider possible modification of equation of state for the holographic energy density in lorentz invariance violation cosmology. In this case we select Jeans length as the IR cut-off in the holographic model. Then we consider the interaction between holographic energy densities ρΛ and ρm in this framework.

scholarly journals SUPERNOVA Ia AND GALAXY CLUSTER GAS MASS FRACTION CONSTRAINTS ON DARK ENERGY

2006 ◽  
Vol 21 (29) ◽  
pp. 2197-2204 ◽  
Author(s):  
KYLE M. WILSON ◽  
GANG CHEN ◽  
BHARAT RATRA
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Mass Fraction ◽  
Galaxy Cluster ◽  
Apparent Magnitude ◽  
Model Parameters ◽  
Dark Energy Density ◽  
Energy Models ◽  
Fraction Versus

We use the Riess et al. (2004)1 supernova Ia apparent magnitude versus redshift data and the Allen et al. (2004)2 galaxy cluster gas mass fraction versus redshift data to constrain dark energy models. These data provide complementary constraints that when combined together significantly restrict model parameters and favor slowly-evolving dark energy density models, close to the Einstein cosmological constant limit of dark energy.

scholarly journals SECOND-ORDER INVARIANTS AND HOLOGRAPHY

2012 ◽  
Vol 21 (12) ◽  
pp. 1250091 ◽  
Author(s):  
ORLANDO LUONGO ◽  
LUCA BONANNO ◽  
GERARDO IANNONE
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Holographic Dark Energy ◽  
Statistical Tests ◽  
A Priori ◽  
Second Order ◽  
Fine Tuning ◽  
Dark Energy Density ◽  
Event Horizons

Motivated by recent works on the role of the holographic principle in cosmology, we relate a class of second-order Ricci invariants to the IR cutoff characterizing the holographic dark energy density. The choice of second-order invariants provides an invariant way to account the problem of causality for the correct cosmological cutoff, since the presence of event horizons is not an a priori assumption. We find that these models work fairly well, by fitting the observational data, through a combined cosmological test with the use of SNeIa, BAO and CMB. This class of models is also able to overcome the fine-tuning and coincidence problems. Finally, to make a comparison with other recent models, we adopt the statistical tests AIC and BIC.

scholarly journals POWER-LAW ENTROPY CORRECTED NEW HOLOGRAPHIC SCALAR FIELD MODELS OF DARK ENERGY WITH MODIFIED IR-CUTOFF

2011 ◽  
Vol 26 (33) ◽  
pp. 2487-2499 ◽  
Author(s):  
A. KHODAM-MOHAMMADI
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Kinetic Energy ◽  
Holographic Dark Energy ◽  
Matter Field ◽  
Dark Energy Density ◽  
Energy Models ◽  
Scalar Field Models ◽  
Phantom Barrier ◽  
Limiting Case

In this work, the PLECHDE model with Granda–Oliveros (G–O) IR-cutoff is studied. The evolution of dark energy density, deceleration and EoS parameters are calculated. I demonstrate that under a condition, our universe can accelerate near the phantom barrier at present time. We calculate these parameters also in PLECHDE at Ricci scale, when α = 2 and β = 1, and a comparison between Ricci scale, G–O cutoff and non-corrected HDE without matter field with G–O cutoff is done. The correspondence between this model and some scalar field of dark energy models is established. By this method, the evolutionary treatment of kinetic energy and potential for quintessence, tachyon, K-essence and dilaton fields, are obtained. I show that the results has a good compatibility with previous work in the limiting case of flat, dark dominated and non-corrected holographic dark energy.

scholarly journals CAN THE EXISTENCE OF DARK ENERGY BE DIRECTLY DETECTED?

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3426-3436 ◽  
Author(s):  
MARTIN L. PERL
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Total Mass ◽  
Mass Density ◽  
Mass Energy ◽  
Dark Energy Density ◽  
Astronomical Observations ◽  
Expansion Of The Universe ◽  
The Universe

Over the last decade, astronomical observations show that the acceleration of the expansion of the universe is greater than expected from our understanding of conventional general relativity, the mass density of the visible universe, the size of the visible universe and other astronomical measurements. The additional expansion has been attributed to a variety of phenomenon that have been given the general name of dark energy. Dark energy in the universe seems to comprise a majority of the energy in the visible universe amounting to about three times the total mass energy. But locally the dark energy density is very small. However it is not zero. In this paper I describe the work of others and myself on the question of whether dark energy density can be directly detected. This is a work-in-progress and I have no answer at present.

scholarly journals COSMO MSW EFFECT FOR MASS VARYING NEUTRINOS

2005 ◽  
Vol 20 (16) ◽  
pp. 1209-1215 ◽  
Author(s):  
PHAM QUANG HUNG ◽  
HEINRICH PÄS
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Neutrino Mass ◽  
Neutrino Masses ◽  
Mass Variation ◽  
Level Crossing ◽  
Dark Energy Density ◽  
Astrophysical Neutrinos ◽  
The Universe

We consider neutrinos with varying masses which arise in scenarios relating neutrino masses to the dark energy density in the universe. We point out that the neutrino mass variation can lead to level crossing and thus a cosmo MSW effect, having dramatic consequences for the flavor ratio of astrophysical neutrinos.

scholarly journals VISCOUS MODIFIED COSMIC CHAPLYGIN GAS COSMOLOGY

2013 ◽  
Vol 22 (09) ◽  
pp. 1350061 ◽  
Author(s):  
B. POURHASSAN
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Nonlinear Equation ◽  
Observational Data ◽  
Function Method ◽  
Chaplygin Gas ◽  
Time Dependent ◽  
Dark Energy Density ◽  
Hubble Expansion ◽  
Exponential Function Method

In this paper, we construct viscous modified cosmic Chaplygin gas as a model of dark energy. We use exponential function method to solve nonlinear equation and obtain time-dependent dark energy density. Then, we discuss Hubble expansion parameter and scale factor and fix them by using observational data. Effect of viscosity to the evolution of Universe is investigated. We also investigate stability of this theory.

Diagnosing Tsallis holographic dark energy models with statefinder and ω − ω′ pair

2019 ◽  
Vol 34 (13) ◽  
pp. 1950101 ◽  
Author(s):  
Umesh Kumar Sharma ◽  
Anirudh Pradhan
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Holographic Dark Energy ◽  
Tsallis Entropy ◽  
Observation Data ◽  
Energy Models ◽  
Evolutionary Trajectories

A useful method, known as statefinder diagnostic, which may differentiate one dark energy (DE) model from others is applied in this work to a holographic dark energy (HDE) model from Tsallis entropy, called the Tsallis holographic dark energy (THDE) model. The evolutionary trajectories of this model are plotted in the statefinder parameter — planes and [Formula: see text] plane, and it is observed that the parameter [Formula: see text] of this model plays a magnificent role from the statefinder and [Formula: see text] plane viewpoints. Eventually, the evolutionary trajectories are plotted considering two different values of THDE energy density ([Formula: see text]), [Formula: see text], in the light of Planck 2018 results VI base-LCDM cosmology and [Formula: see text], in the light of SNe + BAO + OHD + CMB observation data.

scholarly journals EXOTIC LOW DENSITY FERMION STATES IN THE TWO MEASURES FIELD THEORY: NEUTRINO DARK ENERGY

2006 ◽  
Vol 21 (21) ◽  
pp. 4373-4406 ◽  
Author(s):  
E. I. GUENDELMAN ◽  
A. B. KAGANOVICH
Keyword(s):  
Field Theory ◽  
Dark Energy ◽  
Scalar Field ◽  
Energy Density ◽  
Energy Momentum Tensor ◽  
Neutrino Energy ◽  
Momentum Tensor ◽  
Dark Energy Density ◽  
Two Measures ◽  
The Universe

There exist field theory models where the fermionic energy–momentum tensor contains a term proportional to [Formula: see text] which may contribute to the dark energy. We show that this new field theory effect can be achieved in the Two Measures Field Theory (TMT) in the cosmological context. TMT is an alternative gravity and matter field theory where the gravitational interaction of fermionic matter is reduced to that of General Relativity when the energy density of the fermion matter is much larger than the dark energy density. In this case also the fifth force problem is solved automatically. In the opposite limit, where the magnitudes of fermionic energy density and scalar field dark energy density become comparable, nonrelativistic fermions can participate in the cosmological expansion in a very unusual manner. Some of the features of such Cosmo-Low-Energy-Physics (CLEP) states are studied in a toy model of the late time universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos, and the following results are obtained: neutrino mass increases as m ∝ a3/2 (a is the scale factor); the proportionality factor in the noncanonical contribution to the neutrino energy–momentum tensor (proportional to the metric tensor) approaches a constant as a(t) → ∞ and therefore the noncanonical contribution to the neutrino energy density dominates over the canonical one ~ m/a3 ~ a-3/2 at the late enough universe; hence the neutrino gas equation-of-state approaches w = -1, i.e. neutrinos in the CLEP regime behave as a sort of dark energy as a → ∞; the equation-of-state for the total (scalar field + neutrino) energy density and pressure also approaches w = -1 in the CLEP regime; besides the total energy density of such universe is less than it would be in the universe filled with the scalar field alone. An analytic solution is presented. A domain structure of the dark energy seems to be possible. We speculate that decays of the CLEP state neutrinos may be both an origin of cosmic rays and responsible for a late super-acceleration of the universe. In this sense the CLEP states exhibit simultaneously new physics at very low densities and for very high particle masses.

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