scholarly journals Interacting F(R, T) gravity with modified Chaplygin gas

2015 ◽  
Vol 93 (12) ◽  
pp. 1453-1459 ◽  
Author(s):  
Ali R. Amani ◽  
S.L. Dehneshin
Keyword(s):  
Dark Energy ◽  
Sound Speed ◽  
Cosmological Parameters ◽  
Field Potential ◽  
Chaplygin Gas ◽  
Accelerated Expansion ◽  
Late Time ◽  
Modified Chaplygin Gas ◽  
Curvature And Torsion ◽  
The Universe

In this paper, we have studied F(R, T) gravity as an arbitrary function of curvature and torsion scalars in Friedmann–Lemaître–Robertson–Walker background. Then, we have considered interacting model between F(R, T) gravity and modified Chaplygin gas. The novelty of this model is that the Universe includes both curvature and torsion cases, and one dominated by a Chaplygin gas. To calculate cosmological solutions, we obtained the Friedmann equations and also equation of state parameter of dark energy. By employing the interacting model we considered the total energy density and the total pressure of the Universe as the combination of components of dark energy and Chaplygin gas. Subsequently, we reconstructed the model by an origin of a scalar field entitled quintessence model with a field potential. The field potential has been calculated in terms of free parameters of F(R, T) gravity and modified Chaplygin gas. In what follows, we used a parametrization, and the cosmological parameters have been written in terms of redshift z. Next, we plotted cosmological parameters with respect to three variables: cosmic time, redshift z, and e-folding number N = ln(a), and the figures showed us an accelerated expansion of the Universe. Also, we have described the scenario in three statuses: early time, late time, and future time, by e-folding number. Finally, the stability of the scenario has been investigated using sound speed, and the graph of sound speed versus e-folding number has shown us that there is stability in late time.

scholarly journals Stability and interacting f(T, T ) gravity with modified Chaplygin gas

2017 ◽  
Vol 95 (11) ◽  
pp. 1068-1073 ◽  
Author(s):  
T. Mirzaei Rezaei ◽  
Alireza Amani
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Teleparallel Gravity ◽  
Chaplygin Gas ◽  
Accelerated Expansion ◽  
Phase Plane Analysis ◽  
Modified Chaplygin Gas ◽  
Continuity Equations ◽  
The Stability ◽  
The Universe

In this paper, the model of interaction is studied between f(T, [Formula: see text]) gravity and modified Chaplygin gas in Friedmann–Robertson–Walker (FRW)-flat metric. We obtain the Friedmann equations in the framework of teleparallel gravity by vierbein field. We consider that the Universe is dominated by components of cold matter, dark energy, and modified Chaplygin gas. In what follows we separately write the corresponding continuity equations for components of the Universe. Also, dark energy equation of state (EoS) and effective EoS are obtained with respect to redshift, thereinafter the corresponding cosmological parameters are plotted in terms of redshift, thereinafter the accelerated expansion of the Universe is investigated. Finally, the stability of the model is discussed in phase plane analysis.

scholarly journals Viscous interacting and stability on dark matter Bose-Einstein condensation with modified Chaplygin gas

2021 ◽  
Author(s):  
E. Mahichi ◽  
Alireza Amani ◽  
M.A. Ramzanpour
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Accelerated Expansion ◽  
Einstein Condensation ◽  
Modified Chaplygin Gas ◽  
Bose Einstein Condensation ◽  
Bose Einstein ◽  
The Universe

In this paper, the viscous cosmological dynamics are studied in the presence of dark matter Bose-Einstein Condensation (BEC) by curved-FRW background. For this purpose, we use the BEC regime rather than the normal dark matter (the cold dark matter or the barotropic dark matter) with the dark matter Equation of State (EoS) as p<sub>dm </sub>∝ p<sup>2</sup><sub>dm</sub>, which arises from the gravitational form. Therefore, we obtain the corresponding continuity equations with the existence of the universe components by considering an interacting model with modified Chaplygin gas. Afterward, we derive the energy density and the pressure of dark energy in terms of the redshift parameter. And then, by introducing a parametrization function and fitting it with 51 supernova data with the likelihood analysis, we find the cosmological parameters versus redshift parameter. In what follows, we plot the corresponding dynamic graphs proportional to redshift, and then we represent the universe is currently undergoing an accelerated expansion phase. Finally, we explore the stability and the instability of the present model with the sound speed parameter.

scholarly journals Interacting models of generalized Chaplygin gas and modified Chaplygin gas with barotropic fluid

2019 ◽  
Vol 34 (09) ◽  
pp. 1950064 ◽  
Author(s):  
Promila Biswas ◽  
Ritabrata Biswas
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Cosmic Acceleration ◽  
Late Time ◽  
Modified Chaplygin Gas ◽  
Interaction Coefficients ◽  
Generalized Chaplygin Gas ◽  
Barotropic Fluid

In this paper, we consider two different models of our present universe. We choose the models which consist of different sets of two separate fluids. The first one of each set tries to justify the late time acceleration and the second one is barotropic fluid. The former model considers our present time universe to be homogeneously filled up by Generalized Chaplygin Gas which is interacting with barotropic fluid. On the other hand, the latter model considers that the cosmic acceleration is generated by Modified Chaplygin Gas which is interacting with matter depicted by barotropic equation of state (EoS). For both the models, we consider the interaction term to vary proportionally with Hubble’s parameter as well as with the exotic matter/dark energy’s energy density. We find an explicit function form of the energy density of the cosmos which is found to depend on different cosmological parameters like scale factor, dark energy and barotropic fluid’s EoS parameters and other constants, like interacting constants, etc. We draw curves of effective EoS-s, different cosmological parameters like deceleration parameter q, statefinder parameters r and s with respect to the redshift z (for different values of dark energy and barotropic fluid parameters) and study them thoroughly. We compare two models as well as the nature of dependencies on these models’ interaction coefficients. We point out the particular redshift for which the universe may transit from a deceleration to acceleration phase. We tally all these values with different observational data. Here, we also analyze how this value of particular redshift does change for different values of interaction coefficients and different dark energy models.

Sharma–Mittal holographic dark energy model in conharmonically flat space-time

2020 ◽  
Vol 18 (01) ◽  
pp. 2150002
Author(s):  
Vipin Chandra Dubey ◽  
Umesh Kumar Sharma ◽  
Anirudh Pradhan
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Field Potential ◽  
Flat Space ◽  
Accelerated Expansion ◽  
Frw Universe ◽  
Eos Parameter ◽  
Expansion Of The Universe ◽  
Quintessence Field ◽  
The Universe

In this work, we explore the accelerated expansion of the conharmonically flat space in relation to an isotropic and spatially homogeneous Friedmann–Robertson–Walker (FRW) universe through a newly proposed dark energy (DE) model namely Sharma–Mittal holographic DE (SMHDE) by taking Hubble horizon as an IR cut-off and also by considering the deceleration parameter as a linear function of Hubble parameter as [Formula: see text], where [Formula: see text] and [Formula: see text] are arbitrary constants. The analysis of different cosmological parameters, equation of state (EoS) parameter, squared speed of sound, statefinder, [Formula: see text] pair, and quintessence field model has been calculated and discussed in detail. Analyzing the behavior of such cosmological parameters graphically, it is found that the SMHDE model can lead to the accelerated expansion of the universe at present epoch. We have also reconciled the DE with scalar field potential. For this analysis, we take into account the quintessence field for this reconstruction.

Kaluza–Klein dark energy model in the form of wet dark fluid in f(R, T) gravity

2014 ◽  
Vol 92 (9) ◽  
Author(s):  
P.K. SAHOO ◽  
B. Mishra
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Accelerated Expansion ◽  
Physical Parameters ◽  
Late Time ◽  
Field Equations ◽  
Wet Dark Fluid ◽  
Dark Fluid ◽  
The Universe ◽  
Kaluza Klein

A five dimensional Kaluza-Klein space time is considered with wet dark fluid (WDF) source in the framework of f(R,T) gravity, where R is the Ricci scalar and T is the trace of the energy-momentum tensor proposed by Harko et al. (Phys. Rev. D \textbf{84}, 024020, (2011)). A new equation of state in the form of WDF has been used for dark energy (DE) component of the universe. It is modeled on the equation of state p=\omega(\rho-\rho^*) which can be describing a liquid, for example water. The exact solutions to the corresponding field equations are obtained for power law and exponential law of the volumetric expansion. The geometrical and physical parameters for both the models are studied. The model obtained here may represent the inflationary era in the early universe and the very late time of the universe. This model obtained here shows that even in the presence of wet dark fluid, the universe indicates accelerated expansion of the universe.

ENTROPY CORRECTED HOLOGRAPHIC DARK ENERGY f(T) GRAVITY MODEL

2014 ◽  
Vol 29 (02) ◽  
pp. 1450015 ◽  
Author(s):  
M. SHARIF ◽  
SHAMAILA RANI
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Phase Plane ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Accelerated Expansion ◽  
Statefinder Parameters ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Evolution Trajectory

This paper is devoted to study the power-law entropy corrected holographic dark energy (ECHDE) model in the framework of f(T) gravity. We assume infrared (IR) cutoff in terms of Granda–Oliveros (GO) length and discuss the constructed f(T) model in interacting as well as in non-interacting scenarios. We explore some cosmological parameters like equation of state (EoS), deceleration, statefinder parameters as well as ωT–ωT′ analysis. The EoS and deceleration parameters indicate phantom behavior of the accelerated expansion of the universe. It is mentioned here that statefinder trajectories represent consistent results with ΛCDM limit, while evolution trajectory of ωT–ωT′ phase plane does not approach to ΛCDM limit for both interacting and non-interacting cases.

Kaluza–Klein dark energy model in the form of wet dark fluid in f(R, T) gravity

2014 ◽  
Vol 92 (9) ◽  
pp. 1062-1067 ◽  
Author(s):  
P. K. Sahoo ◽  
B. Mishra
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Accelerated Expansion ◽  
Physical Parameters ◽  
Late Time ◽  
Field Equations ◽  
Wet Dark Fluid ◽  
Dark Fluid ◽  
The Universe ◽  
Kaluza Klein

In this paper, we have investigated the five-dimensional Kaluza–Klein space time with wet dark fluid (WDF), which is a candidate for dark energy (DE), in the framework of f(R, T) gravity. R and T denote the Ricci scalar and the trace of the energy–momentum tensor, respectively (Harko et al. Phys. Rev. D, 84, 024020 (2011)). We have used equation of state in the form of WDF for the DE component of the universe. It is modeled on the equation of state p = ω(ρ – ρ*). With the help of the power law and exponential law of volumetric expansion, we have derived the exact solutions of the corresponding field equations. The geometrical and physical parameters for both the models are studied. The model obtained here may represent the inflationary era in the early universe and very late time of the universe. It is concluded that the model obtained here shows that even in the presence of WDF, the universe indicates accelerated expansion of the universe.

scholarly journals A novel teleparallel dark energy model

2016 ◽  
Vol 25 (02) ◽  
pp. 1650025 ◽  
Author(s):  
Giovanni Otalora
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Teleparallel Gravity ◽  
Accelerated Expansion ◽  
Late Time ◽  
De Sitter ◽  
Sitter Group ◽  
Current State ◽  
Expansion Of The Universe ◽  
The Universe

Although equivalent to general relativity, teleparallel gravity (TG) is conceptually speaking a completely different theory. In this theory, the gravitational field is described by torsion, not by curvature. By working in this context, a new model is proposed in which the four-derivative of a canonical scalar field representing dark energy is nonminimally coupled to the “vector torsion”. This type of coupling is motivated by the fact that a scalar field couples to torsion through its four-derivative, which is consistent with local spacetime kinematics regulated by the de Sitter group [Formula: see text]. It is found that the current state of accelerated expansion of the universe corresponds to a late-time attractor that can be (i) a dark energy-dominated de Sitter solution ([Formula: see text]), (ii) a quintessence-type solution with [Formula: see text], or (iii) a phantom-type [Formula: see text] dark energy.

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.

Generalized interaction term inspired dark energy model in fractal universe

2020 ◽  
Vol 35 (15) ◽  
pp. 2050126
Author(s):  
Abdul Jawad ◽  
Saba Qummer ◽  
Shamaila Rani ◽  
M. Younas
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Energy Model ◽  
Linear Term ◽  
Accelerated Expansion ◽  
Linear Interaction ◽  
Interaction Term ◽  
The Universe

By assuming generalized nonlinear and linear interaction term between dark matter and dark energy, we investigate the cosmic accelerated expansion of the universe. For this reason, we suppose a flat fractal universe platform as well as Tsallis holographic dark energy model. The Hubble horizon is being adopted as an infrared cutoff and extracted different cosmological parameters as well as plane. It is observed that equation-of-state parameter exhibits the quintom-like nature while ([Formula: see text]–[Formula: see text]) lies in thawing and freezing regions for different parametric values for both the cases. Furthermore, the squared sound speed shows stable behavior for nonlinear interaction term but shows the partially stable behavior for linear term. For both cases, the deceleration parameter leads to the accelerated phase of the universe and the consequences are comparable with observational data. The results for [Formula: see text]–[Formula: see text] plane, leads to the quintessence and phantom region of the universe for nonlinear case while this plane represents the Chaplygin gas behavior for linear term. The [Formula: see text] diagnostic also shows the satisfying results.

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