scholarly journals Coupled tachyonic dark energy: A dynamical analysis

2015 ◽  
Vol 24 (11) ◽  
pp. 1550085 ◽  
Author(s):  
Ricardo C. G. Landim
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Critical Points ◽  
Autonomous System ◽  
Evolution Equations ◽  
Dynamical Analysis ◽  
Tachyonic Field ◽  
Barotropic Fluids ◽  
Tachyonic Dark Energy

In this paper, we present a dynamical analysis for a coupled tachyonic dark energy with dark matter. The tachyonic field ϕ is considered in the presence of barotropic fluids (matter and radiation) and the autonomous system due to the evolution equations is studied. The three cosmological eras (radiation, matter and dark energy) are described through the critical points, for a generic potential V(ϕ).

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.

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 An explanation for dark matter and dark energy consistent with the standard model of particle physics and General Relativity

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Alexandre Deur
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Particle Physics ◽  
Evolution Equations ◽  
Gravitational Interaction ◽  
Interaction Effects ◽  
Law Of Gravity ◽  
The Universe ◽  
Universe Evolution

Abstract Analyses of internal galaxy and cluster dynamics typically employ Newton’s law of gravity, which neglects the field self-interaction effects of General Relativity. This may be why dark matter seems necessary. The universe evolution, on the other hand, is treated with the full theory, General Relativity. However, the approximations of isotropy and homogeneity, normally used to derive and solve the universe evolution equations, effectively suppress General Relativity’s field self-interaction effects and this may introduce the need for dark energy. Calculations have shown that field self-interaction increases the binding of matter inside massive systems, which may account for galaxy and cluster dynamics without invoking dark matter. In turn, energy conservation dictates that the increased binding must be balanced by an effectively decreased gravitational interaction outside the massive system. In this article, such suppression is estimated and its consequence for the Universe’s evolution is discussed. Observations are reproduced without need for dark energy.

scholarly journals Tachyonic Teleparallel Dark Energy in Phase Space

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Behnaz Fazlpour ◽  
Ali Banijamali
Keyword(s):  
Dark Energy ◽  
Phase Space ◽  
Scalar Field ◽  
Critical Points ◽  
Dynamical Analysis ◽  
Accelerating Universe ◽  
Nonminimal Coupling ◽  
Tachyon Field ◽  
Critical Lines

Recently, nonminimal coupling between a noncanonical scalar field and gravity in the framework of teleparallelism has been proposed. Noncanonical scalar field is tachyon field, and the model is known as tachyonic teleparallel dark energy. Here, we perform a dynamical analysis of the model, find its critical points, and study their stability. We find that all the critical points are dark energy dominated solutions corresponding to an accelerating universe. It is also shown that there exist two critical lines which are stable attractors of the model.

scholarly journals Modified gravity in the framework of holographic dark energy

2019 ◽  
Vol 35 (06) ◽  
pp. 2050025
Author(s):  
L. N. Granda ◽  
G. D. Rojas
Keyword(s):  
Dark Energy ◽  
Critical Points ◽  
Modified Gravity ◽  
Autonomous System ◽  
Holographic Dark Energy

The modified gravity is considered in the framework of the holographic dark energy (DE). An analysis of the autonomous system, the critical points and their stability is presented. Unlike the DE models based on [Formula: see text], it is found that working in the holographic frame enriches the possibility of accelerated and matter-type points for different cosmological scenarios, making viable trajectories of successful [Formula: see text] models that are not allowed without the consideration of the holographic framework. The implications for the Hu–Sawicki model are analyzed.

Effective masses in a dense fermion background — Applied to neutrinos, dark matter and dark energy

2014 ◽  
Vol 29 (21) ◽  
pp. 1444010
Author(s):  
Bruce H. J. McKellar ◽  
T. J. Goldman ◽  
G. J. Stephenson
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Effective Mass ◽  
Negative Pressure ◽  
Expectation Value ◽  
Effective Masses ◽  
Neutrino Astrophysics

If fermions interact with a scalar field, and there are many fermions present the scalar field may develop an expectation value and generate an effective mass for the fermions. This can lead to the formation of fermion clusters, which could be relevant for neutrino astrophysics and for dark matter astrophysics. Because this system may exhibit negative pressure, it also leads to a model of dark energy.

Dark Matter and Dark Energy from the solution of the strong CP problem

2006 ◽  
Author(s):  
Roberto Mainini ◽  
Loris Colombo ◽  
Silvio Bonometto
Keyword(s):  
Dark Matter ◽  
Dark Energy
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