scholarly journals Inhomogeneous viscous dark fluid coupled with dark matter in the FRW universe

2014 ◽  
Vol 29 (25) ◽  
pp. 1450132 ◽  
Author(s):  
E. Elizalde ◽  
V. V. Obukhov ◽  
A. V. Timoshkin
Keyword(s):  
Dark Matter ◽  
Cosmological Model ◽  
Viscous Fluid ◽  
Critical Points ◽  
Cosmic Acceleration ◽  
Frw Universe ◽  
Dark Fluid ◽  
Different Types ◽  
Friedmann Robertson Walker

A cosmological model with an inhomogeneous viscous dark fluid coupled with dark matter in a flat Friedmann–Robertson–Walker (FRW) universe is investigated. The influence of dark matter on the behavior of an inhomogeneous viscous fluid of this kind, responsible for cosmic acceleration and for the appearance of different types of singularities, is analyzed in detail. In particular, the critical points corresponding to the solutions of the background equations in a useful approximation are obtained explicitly.

scholarly journals Generalized model of interacting dark energy and dark matter: Phase portrait analysis for evolving universe

2022 ◽  
Author(s):  
Giridhari Deogharia ◽  
Mayukh Bandyopadhyay ◽  
Ritabrata Biswas
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Phase Portrait ◽  
Critical Points ◽  
Autonomous System ◽  
Cosmic Acceleration ◽  
Accelerating Universe ◽  
Late Time ◽  
Phase Portrait Analysis

The main aim of this work is to give a suitable explanation of present accelerating universe through an acceptable interactive dynamical cosmological model. A three-fluid cosmological model is introduced in the background of Friedmann–Lemaître–Robertson-Walker asymptotically flat spacetime. This model consists of interactive dark matter and dark energy with baryonic matter, taken as perfect fluid, satisfying barotropic equation of state. We consider dust as the candidate of dark matter. A scalar field [Formula: see text] represents dark energy with potential [Formula: see text]. Einstein’s field equations are utilized to construct a three-dimensional interactive autonomous system by choosing suitable interaction between dark energy and dark matter. We take the interaction kernel as [Formula: see text], where [Formula: see text] indicates the density of dark energy, [Formula: see text] is the interacting constant and [Formula: see text] is Hubble parameter. In order to explain the stability of this system, we obtain some suitable critical points. We analyze stability of obtained critical points to show the different phases of universe and cosmological implications. Surprisingly, we find some stable critical points which represent late-time dark energy-dominated era when a model parameter [Formula: see text] is equal to [Formula: see text]. We introduce a two-dimensional interactive autonomous system and after phase portrait analysis of it, we get several stable points which represent dark energy-dominated era and late-time cosmic acceleration simultaneously. Here, we also demonstrate the variation in interaction at vicinity of phantom barrier [Formula: see text]. From our work, we can also predict the future phase evolution of the universe.

scholarly journals Qualitative Analysis of the Dynamics of a Two-Component Chiral Cosmological Model

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 195
Author(s):  
Viktor Zhuravlev ◽  
Sergey Chervon
Keyword(s):  
Asymptotic Behavior ◽  
Cosmological Model ◽  
Qualitative Analysis ◽  
Critical Points ◽  
Scalar Fields ◽  
Two Component ◽  
Different Types ◽  
Asymptotic Dynamics

We present a qualitative analysis of chiral cosmological model (CCM) dynamics with two scalar fields in the spatially flat Friedman–Robertson–Walker Universe. The asymptotic behavior of chiral models is investigated based on the characteristics of the critical points of the selfinteraction potential and zeros of the metric components of the chiral space. The classification of critical points of CCMs is proposed. The role of zeros of the metric components of the chiral space in the asymptotic dynamics is analysed. It is shown that such zeros lead to new critical points of the corresponding dynamical systems. Examples of models with different types of zeros of metric components are represented.

scholarly journals NON-MINIMAL COSMOLOGICAL MODEL IN MODIFIED YANG–MILLS THEORY

2011 ◽  
Vol 26 (26) ◽  
pp. 1965-1973 ◽  
Author(s):  
V. K. SHCHIGOLEV ◽  
G. N. OREKHOVA
Keyword(s):  
Cosmological Model ◽  
Power Law ◽  
Cosmic Acceleration ◽  
Gravitational Coupling ◽  
Frw Cosmology ◽  
General Study ◽  
Yang Mills ◽  
Basic Equations ◽  
M Theory ◽  
Friedmann Robertson Walker

In this paper, we consider a model of non-minimal modified Yang–Mills (Y-M) theory in the Friedmann–Robertson–Walker (FRW) cosmology, in which the Y-M field couples to the scalar curvature through a function of its first invariant. We show that cosmic acceleration can be realized due to non-minimal gravitational coupling of the modified Y-M theory. Besides general study, we consider in detail the case of power-law coupling function. We derive the basic equations for the cosmic scale factor in our model, and provide several examples of their solutions.

scholarly journals A CAUSAL MODEL FOR A CLOSED UNIVERSE

2004 ◽  
Vol 13 (05) ◽  
pp. 871-883
Author(s):  
MAURICIO CATALDO ◽  
SERGIO DEL CAMPO ◽  
PAUL MINNING ◽  
FRANCISCO PEÑA
Keyword(s):  
Viscous Fluid ◽  
Entropy Production ◽  
Causal Model ◽  
Closed Universe ◽  
Frw Universe ◽  
Dynamical Equations ◽  
Closed Model ◽  
The Universe ◽  
Friedmann Robertson Walker ◽  
Causal Thermodynamics

We study a closed model of a universe filled with viscous fluid and quintessence matter components. The dynamical equations imply that the universe might look like an accelerated flat Friedmann–Robertson–Walker (FRW) universe at low redshift. We consider here dissipative processes which obey a causal thermodynamics. Here, we account for the entropy production via causal dissipative inflation.

scholarly journals ACCELERATING UNIVERSES WITH SCALING DARK MATTER

2001 ◽  
Vol 10 (02) ◽  
pp. 213-223 ◽  
Author(s):  
MICHEL CHEVALLIER ◽  
DAVID POLARSKI
Keyword(s):  
Dark Matter ◽  
Equation Of State ◽  
Energy Density ◽  
Critical Points ◽  
Equations Of State ◽  
Large Fraction ◽  
Accurate Knowledge ◽  
Friedmann Robertson Walker

Friedmann–Robertson–Walker universes with a presently large fraction of the energy density stored in an X-component with wX<-1/3, are considered. We find all the critical points of the system for constant equations of state in that range. We consider further several background quantities that can distinguish the models with different wXvalues. Using a simple toy model with a varying equation of state, we show that even a large variation of wXat small redshifts is very difficult to observe with dL(z) measurements up to z~1. Therefore, it will require accurate measurements in the range 1<z<2 and independent accurate knowledge of Ωm,0(and/or ΩX,0) in order to resolve a variable wXfrom a constant wX.

scholarly journals Study of thermal stability for different dark energy models

2019 ◽  
Vol 16 (11) ◽  
pp. 1950171
Author(s):  
Abdulla Al Mamon ◽  
Pritikana Bhandari ◽  
Subenoy Chakraborty
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Point Of View ◽  
Frw Universe ◽  
Generalized Chaplygin Gas ◽  
Dark Fluid ◽  
Energy Models

In this work, we have made an attempt to investigate the dark energy possibility from the thermodynamical point of view. For this purpose, we have studied thermodynamic stability of three popular dark energy models in the framework of an expanding, homogeneous, isotropic and spatially flat FRW Universe filled with dark energy and cold dark matter. The models considered in this work are Chevallier–Polarski–Linder (CPL) model, Generalized Chaplygin Gas (GCG) model and Modified Chaplygin Gas (MCG) model. By considering the cosmic components (dark energy and cold dark matter) as perfect fluid, we have examined the constraints imposed on the total equation of state parameter ([Formula: see text]) of the dark fluid by thermodynamics and found that the phantom nature ([Formula: see text]) is not thermodynamically stable. Our investigation indicates that the dark fluid models (CPL, GCG and MCG) are thermodynamically stable under some restrictions of the parameters of each model.

Cosmology via thermodynamics of polytropic gas

2017 ◽  
Vol 32 (32) ◽  
pp. 1750177 ◽  
Author(s):  
Muzaffer Askin ◽  
Mustafa Salti ◽  
Oktay Aydogdu
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Energy Density ◽  
Exact Expression ◽  
Frw Universe ◽  
Polytropic Gas ◽  
Friedmann Robertson Walker ◽  
Matter Energy

We study cosmological scenarios of the polytropic gas (PG) dark matter-energy proposal in a Friedmann–Robertson–Walker (FRW) Universe. As a first step, we obtain an exact expression for the energy density of PG model by making use of the thermodynamics. Later, we investigate some cosmological quantities and perform neo-classical analyzes. Finally, we implement a connection between the PG and a homogenous minimally coupled scalar field by introducing its self-interacting potential.

scholarly journals THE COSMOLOGICAL DYNAMICS OF INTERACTING HOLOGRAPHIC DARK ENERGY MODEL

2009 ◽  
Vol 18 (01) ◽  
pp. 147-157 ◽  
Author(s):  
M. R. SETARE ◽  
ELIAS C. VAGENAS
Keyword(s):  
Dark Energy ◽  
Cosmological Model ◽  
Critical Points ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Cosmic Acceleration ◽  
Holographic Dark Energy Model ◽  
Evolution Of The Universe ◽  
Energy Scenario ◽  
The Universe

Motivated by the recent observations for cosmic acceleration and the suitable evolution of the universe provided an interaction (decay of dark energy to matter) is incorporated in a cosmological model, we study the cosmological evolution of the interacting holographic dark energy scenario. Critical points are derived and their corresponding cosmological models are presented. The dynamical character of these models is revealed.

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 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.

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