scholarly journals Limits on the Reconstruction of a Single Dark Energy Scalar Field Potential from SNe Ia Data

Particles ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 3 ◽  
Author(s):  
Arpine Piloyan ◽  
Sergey Pavluchenko ◽  
Luca Amendola
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Field Potential ◽  
Energy Scalar

scholarly journals Direct reconstruction of the dark energy scalar-field potential

2007 ◽  
Vol 75 (10) ◽  
Author(s):  
Chao Li ◽  
Daniel E. Holz ◽  
Asantha Cooray
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Field Potential ◽  
Energy Scalar

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.

The BICEP2 data and a single Higgs-like interacting scalar field

2014 ◽  
Vol 23 (09) ◽  
pp. 1450075 ◽  
Author(s):  
Murli Manohar Verma ◽  
Shankar Dayal Pathak
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Gravity Waves ◽  
Field Potential ◽  
Thermodynamical Equilibrium ◽  
Conservation Of Energy ◽  
Order Of Magnitude ◽  
Acceleration Of The Universe ◽  
The Universe ◽  
Perturbed Equation

It is proposed that the recently announced BICEP2 value of tensor-to-scalar ratio r ~ 0.2 can be explained as containing an extra contribution from the recent acceleration of the universe. In fact this contribution, being robust, recent and of much longer duration (by a large order of magnitude) may dominate the contribution from the inflationary origin. In a possible scenario, matter (dark or baryonic) and radiation etc. can emerge from a single Higgs-like tachyonic scalar field in the universe through a physical mechanism not yet fully known to us. The components interact among themselves to achieve the thermodynamical equilibrium in the evolution of the universe. The field potential for the present acceleration of the universe would give a boost to the amplitude of the tensor fluctuations of gravity waves generated by the early inflation and the net effects may be higher than the earlier Planck bounds. In the process, the dark energy, as a cosmological constant decays into creation of dark matter. The diagnostics for the three-component, spatially homogeneous tachyonic scalar field are discussed in detail. The components of the field with perturbed equation of state (EoS) are taken to interact mutually and the conservation of energy for individual components gets violated. We study mainly the Om(x) diagnostics with the observed set of H(z) values at various redshifts, and the dimensionless statefinders for these interacting components. This analysis provides a strong case for the interacting dark energy in our model.

scholarly journals Quantum Cosmologies Under Geometrical Unification of Gravity and Dark Energy

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 860 ◽  
Author(s):  
Carlos A. Rubio ◽  
Felipe A. Asenjo ◽  
Sergio A. Hojman
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Field Potential ◽  
Constraint Equation ◽  
Spinless Particle ◽  
Quantization Scheme ◽  
Dynamical Equations ◽  
Order Constraint ◽  
The Universe ◽  
Friedmann Robertson Walker

A Friedmann–Robertson–Walker Universe was studied with a dark energy component represented by a quintessence field. The Lagrangian for this system, hereafter called the Friedmann–Robertson–Walker–quintessence (FRWq) system, was presented. It was shown that the classical Lagrangian reproduces the usual two (second order) dynamical equations for the radius of the Universe and for the quintessence scalar field, as well as a (first order) constraint equation. Our approach naturally unified gravity and dark energy, as it was obtained that the Lagrangian and the equations of motion are those of a relativistic particle moving on a two-dimensional, conformally flat spacetime. The conformal metric factor was related to the dark energy scalar field potential. We proceeded to quantize the system in three different schemes. First, we assumed the Universe was a spinless particle (as it is common in literature), obtaining a quantum theory for a Universe described by the Klein–Gordon equation. Second, we pushed the quantization scheme further, assuming the Universe as a Dirac particle, and therefore constructing its corresponding Dirac and Majorana theories. With the different theories, we calculated the expected values for the scale factor of the Universe. They depend on the type of quantization scheme used. The differences between the Dirac and Majorana schemes are highlighted here. The implications of the different quantization procedures are discussed. Finally, the possible consequences for a multiverse theory of the Dirac and Majorana quantized Universe are briefly considered.

scholarly journals Interacting dark energy model in the brane scenario: A dynamical system analysis

2019 ◽  
Vol 16 (08) ◽  
pp. 1950115
Author(s):  
Sujay Kr. Biswas ◽  
Subenoy Chakraborty
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Critical Points ◽  
System Analysis ◽  
Evolution Equations ◽  
Field Potential ◽  
Brane Cosmology ◽  
Brane Model ◽  
Barotropic Equation

The present work is a second in the series of investigations of the background dynamics in brane cosmology when dark energy is coupled to dark matter by a suitable interaction. Here, dark matter is chosen in the form of perfect fluid with barotropic equation of state, while a real scalar field with self-interacting potential is chosen as dark energy. The scalar field potential is chosen as exponential or hyperbolic in nature and three different choices for the interactions between the dark species are considered. In the background of spatially flat, homogeneous and isotropic Friedmann–Robertson–Walker (FRW) brane model, the evolution equations are reduced to an autonomous system by suitable transformation of variables and a series of critical points are obtained for different interactions. By analyzing the critical points, we have found a cosmologically viable model describing an early inflationary scenario to dark energy-dominated era connecting through a matter-dominated phase.

Tsallis holographic dark energy models in axially symmetric space time

2020 ◽  
Vol 17 (01) ◽  
pp. 2050011 ◽  
Author(s):  
Vipin Chandra Dubey ◽  
Ambuj Kumar Mishra ◽  
Shikha Srivastava ◽  
Umesh Kumar Sharma
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Holographic Dark Energy ◽  
Field Potential ◽  
Accelerated Expansion ◽  
Anisotropic Universe ◽  
Axially Symmetric ◽  
Eos Parameter ◽  
Quintessence Field ◽  
The Universe

In this work, we have examined the behavior of Bianchi-I (axially symmetric) matter-dominated and the anisotropic Universe with the proposed dark energy, Tsallis holographic dark energy (THDE), with the Hubble horizon as infrared cut-off [Tavayef et al., Tsallis holographic dark energy, Phys. Lett. B 781 (2018) 195–200]. The Universe evolution from matter-dominated epoch to dark energy dominated epoch is described by our proposed THDE model. The EoS parameter in our THDE model explains the evolution of the Universe according to the value of nonextensive or Tsallis parameter [Formula: see text], phantom era ([Formula: see text]) or quintom (phantom line crossing) and the quintessence era ([Formula: see text]), before reaching to completely dark energy-dominated era in the future. Additionally, we also plan to reconcile the dark energy by the method of reconstructing the evolution of the scalar field potential. For the analysis, we take into account the quintessence field and phantom scalar field for this reconstruction, which at present shows the accelerated expansion.

scholarly journals Minimal-supersymmetric extended inflation field in Horava–Lifshitz gravity

2017 ◽  
Vol 26 (14) ◽  
pp. 1750166 ◽  
Author(s):  
Abdel Nasser Tawfik ◽  
Abdel Magied Diab ◽  
Eiman Abou El Dahab
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Spectral Density ◽  
Equations Of State ◽  
Field Potential ◽  
Density Fluctuations ◽  
Friedmann Equations ◽  
Cosmic Background ◽  
Theories Of Gravity ◽  
Scalar Perturbations

We study the Friedmann inflation in general covariant Horava–Lifshitz gravity (HLG) without the projectability conditions and with detailed and nondetailed balance conditions. Accordingly, we derive modifications in the Friedmann equations due to a single-scalar field potential describing minimal-supersymmetrically extended inflation. By implementing two time-independent equations of state (EoS) characterizing the cosmic background geometry filled up with dark energy, the dependence of the tensorial and scalar density fluctuations and their ratios on the inflation field are determined. The latter refers to the time evolution of the inflationary field relative to the Hubble parameter. Furthermore, the ratios of tensorial-to-spectral density fluctuations are calculated in dependence on the spectral index. For cold dark energy EoS [Formula: see text], we find that the tensorial-to-spectral density fluctuations are not depending on the different theories of gravity and the results are very small relative to the recent BICEP2/Keck Array-Planck observations, [Formula: see text]. We have also calculated the tensorial and scalar perturbations of the primordial spectra.

Dynamical system analysis for a scalar–tensor model with Gauss–Bonnet coupling

2019 ◽  
Vol 16 (03) ◽  
pp. 1950044
Author(s):  
Behnaz Fazlpour ◽  
Ali Banijamali
Keyword(s):  
Dynamical System ◽  
Dark Energy ◽  
Scalar Field ◽  
Critical Points ◽  
System Analysis ◽  
Field Potential ◽  
Tensor Model ◽  
Coincidence Problem ◽  
Perturbation Matrix ◽  
Dynamical System Method

In this paper, we study the dynamics of a scalar–tensor model of dark energy in which a scalar field that plays the role of dark energy, non-minimally coupled to the Gauss–Bonnet invariant in four dimensions. We utilize the dynamical system method to extract the critical points of the model and to conclude about their stability, we investigate the sign of the corresponding eigenvalues of the perturbation matrix at each point numerically. For exponential form of the scalar field potential and coupling function, we find five stable points among the critical points of the autonomous system. We also find four scaling attractor solutions with the property that the ratio of dark energy to dark matter density parameters are of order one. These solutions give the hope to alleviate the well-known coincidence problem in cosmology.

A new potential for scalar field dark energy

2020 ◽  
Vol 17 (09) ◽  
pp. 2050139
Author(s):  
Abdulla Al Mamon
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Equation Of State ◽  
Hubble Parameter ◽  
Time Derivative ◽  
Field Potential ◽  
State Parameter ◽  
Simple Relation ◽  
Scale Factor ◽  
Equation Of State Parameter

In this paper, we have investigated some cosmological consequences of a quintessence dark energy model. In particular, we have obtained the forms of the equation of state parameter, the deceleration parameter and the field potential by considering a simple relation between the scale factor and the time derivative of the scalar field, instead of assuming any functional form for the scalar field potential or the scale factor or the equation of state parameter. We have found that the model provides the desired early deceleration followed by present acceleration of the universe. The potential derived numerically in this work in the form [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text] are real constant parameters. It has also been found that our model mimics as the standard [Formula: see text]CDM model in future. Finally, we have also shown the evolution of the normalized Hubble parameter for our model and the [Formula: see text]CDM model and compared that with the latest Hubble parameter data.

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