scholarly journals Role of the Brans–Dicke scalar in the holographic description of dark energy

2005 ◽  
Vol 628 (1-2) ◽  
pp. 11-17 ◽  
Author(s):  
Hungsoo Kim ◽  
H.W. Lee ◽  
Y.S. Myung
Keyword(s):  
Dark Energy ◽  
Holographic Description

scholarly journals If Gauss–Bonnet interaction plays the role of dark energy

2007 ◽  
Vol 645 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Abhik Kumar Sanyal
Keyword(s):  
Dark Energy

scholarly journals ROLE OF GENERALIZED COSMIC CHAPLYGIN GAS IN ACCELERATING UNIVERSE: A FIELD THEORETICAL PRESCRIPTION

2013 ◽  
Vol 28 (22) ◽  
pp. 1350102 ◽  
Author(s):  
PRABIR RUDRA
Keyword(s):  
Dark Energy ◽  
Chaplygin Gas ◽  
Point Of View ◽  
Accelerating Universe ◽  
Theoretical Point ◽  
Modified Chaplygin Gas ◽  
Statefinder Parameters ◽  
Generalized Cosmic Chaplygin Gas ◽  
The Given

In this paper, we investigate the role played by dark energy (DE) in the form of Generalized cosmic Chaplygin gas in an accelerating universe described by FRW cosmology. We have tried to describe the model from the theoretical point of view of a field, by introducing a scalar field ϕ and a self-interacting potential V(ϕ). The corresponding expressions for the field are obtained for the given model. Statefinder parameters have been used to characterize the dark energy model. Plots have been generated for characterizing different phases of universe diagrammatically and a comparative study is performed with the Modified Chaplygin gas model. As an outcome of the study, Generalized cosmic Chaplygin gas is identified as a much less constrained form of dark energy as compared to modified Chaplygin gas.

scholarly journals Violation of the Dominant Energy Condition in Geometrodynamics

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 400
Author(s):  
Vladimir Lasukov
Keyword(s):  
Black Holes ◽  
Dark Energy ◽  
Energy Condition ◽  
Dominant Energy Condition ◽  
Isotropic Energy ◽  
Cosmological Singularity ◽  
Dominant Condition ◽  
Field Theoretical Model ◽  
Over Time

It is shown that in Einstein’s theory and in the theory of gravity with Logunov constraints, there is a field-theoretical model of dark energy that is consistent with the observational data indicating that the Hubble value increases over time. In the developed model of dark energy, the isotropic energy dominant condition is violated. It solves the problem of the cosmological singularity and the singularity of “black holes”. The compact configuration of the scalar field can generate a flux of particles by the pairs of particles production mechanism from the vacuum by a field of barrier and in the process of transformation of thermal energy (Hawking radiation) and acceleration energy into radiation. The scalars can play the role of the so-called “black holes” with no singularity inside themselves.

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 Accelerating dark energy cosmological model in two fluids with hybrid scale factor

2017 ◽  
Vol 14 (09) ◽  
pp. 1750124 ◽  
Author(s):  
B. Mishra ◽  
P. K. Sahoo ◽  
Pratik P. Ray
Keyword(s):  
Dark Energy ◽  
Late Phase ◽  
Scale Factor ◽  
Accelerating Universe ◽  
Late Time ◽  
Field Equations ◽  
Geometrical Properties ◽  
Two Fluids ◽  
The Universe

In this paper, we have investigated the anisotropic behavior of the accelerating universe in Bianchi V spacetime in the framework of General Relativity (GR). The matter field we have considered is of two non-interacting fluids, i.e. the usual string fluid and dark energy (DE) fluid. In order to represent the pressure anisotropy, the skewness parameters are introduced along three different spatial directions. To achieve a physically realistic solutions to the field equations, we have considered a scale factor, known as hybrid scale factor, which is generated by a time-varying deceleration parameter. This simulates a cosmic transition from early deceleration to late time acceleration. It is observed that the string fluid dominates the universe at early deceleration phase but does not affect nature of cosmic dynamics substantially at late phase, whereas the DE fluid dominates the universe in present time, which is in accordance with the observations results. Hence, we analyzed here the role of two fluids in the transitional phases of universe with respect to time which depicts the reason behind the cosmic expansion and DE. The role of DE with variable equation of state parameter (EoS) and skewness parameters, is also discussed along with physical and geometrical properties.

THE ROLE OF A CHAMELEON FIELD IN AN ANISOTROPIC UNIVERSE WITH LOGAMEDIATE AND INTERMEDIATE SCENARIOS

2010 ◽  
Vol 25 (24) ◽  
pp. 4691-4701 ◽  
Author(s):  
SHUVENDU CHAKRABORTY ◽  
UJJAL DEBNATH
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Anisotropic Universe ◽  
Anisotropic Model ◽  
Scale Factors ◽  
Slow Roll ◽  
Energy Scalar ◽  
The Universe

In this work, we consider the Universe is being filled with matter composed of a chameleon-type dark energy scalar field. Employing a particular form of potential, we discuss the field's role in the accelerating phase of the Universe for an anisotropic model using the logamediate and intermediate forms of scale factors. The natures of statefinder and slow-roll parameters are discussed diagrammatically.

scholarly journals Cosmological model with fermion and tachyon fields interacting via Yukawa-type potential

2016 ◽  
Vol 31 (06) ◽  
pp. 1650039 ◽  
Author(s):  
Marlos O. Ribas ◽  
Fernando P. Devecchi ◽  
Gilberto M. Kremer
Keyword(s):  
Dark Energy ◽  
Cosmological Model ◽  
Matter Field ◽  
Fermionic Field ◽  
Tachyonic Field ◽  
Fermionic Fields ◽  
The Universe ◽  
Type Potential

A model for the universe with tachyonic and fermionic fields interacting through a Yukawa-type potential is investigated. It is shown that the tachyonic field answers for the initial accelerated regime and for the subsequent decelerated regime so that it behaves as an inflaton at early times and as a matter field at intermediate times, while the fermionic field has the role of a dark energy constituent, since it leads to an accelerated regime at later times. The interaction between the fields via a Yukawa-type potential controls the duration of the decelerated era, since a stronger coupling makes a shorter decelerated period.

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 FLRW cosmology of induced dark energy model and open universe

2017 ◽  
Vol 95 (12) ◽  
pp. 1215-1218 ◽  
Author(s):  
Amir F. Bahrehbakhsh
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Early Time ◽  
Energy Model ◽  
Late Time ◽  
Open Universe ◽  
Fifth Dimension ◽  
Flrw Cosmology

We investigate the Friedmann–Lemaître–Robertson–Walker (FLRW) type cosmology of the induced dark energy model and illustrate that the extra terms emerging from the fifth dimension can play the role of dark energy. The model predicts the expansion with deceleration at early time and acceleration in late time for an open universe.

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