scholarly journals On the occurrence of finite-time singularities in Swampland-related quintessence dark energy models

2021 ◽  
pp. 2150207
Author(s):  
V. K. Oikonomou ◽  
Achilles Gitsis ◽  
Maria Mitrou
Keyword(s):  
Dynamical System ◽  
Dark Energy ◽  
Phase Space ◽  
Finite Time ◽  
Initial Conditions ◽  
Energy Models ◽  
Time Singularities ◽  
Quintessence Model

In this work, we focus on the phase space singularities of interactive quintessence model in the presence of matter fluid. This model is related to swampland studies, that the outcomes affect all these swampland-related models with the same dynamical system. We shall form the dynamical system corresponding to the cosmological system, which is eventually autonomous, and by using the dominant balances technique we shall investigate the occurrence or not of finite-time singularities. Our results indicate that the dynamical system of the model may develop finite-time singularities, but these are not general singularities, like in the case that the matter fluids were absent, in which case singularities occurred for general initial conditions. Hence, the presence of matter fluids affects the dynamical system of the cosmological system, making the singularities to depend on the initial conditions, instead of occurring for general initial conditions.

scholarly journals Finite-time singularities in swampland-related dark-energy models

2019 ◽  
Vol 126 (2) ◽  
pp. 20002 ◽  
Author(s):  
S. D. Odintsov ◽  
V. K. Oikonomou
Keyword(s):  
Dark Energy ◽  
Finite Time ◽  
Energy Models ◽  
Time Singularities

scholarly journals Dynamical system analysis of dark energy models in scalar coupled Metric-Torsion theories

2017 ◽  
Vol 26 (13) ◽  
pp. 1750149 ◽  
Author(s):  
Arshdeep Singh Bhatia ◽  
Sourav Sur
Keyword(s):  
Dark Energy ◽  
Phase Space ◽  
Scalar Field ◽  
System Analysis ◽  
Coupling Parameter ◽  
Cosmological Parameters ◽  
Direct Interaction ◽  
Cosmic Acceleration ◽  
Energy Models ◽  
Space Dynamics

We study the phase-space dynamics of cosmological models in the theoretical formulations of nonminimal metric-torsion couplings with a scalar field, and investigate in particular the critical points (CPs) which yield stable solutions exhibiting cosmic acceleration driven by the dark energy (DE). The latter is so defined that it effectively has no direct interaction with the cosmological fluid, although in an equivalent scalar–tensor cosmological setup, the scalar field interacts with the fluid (which we consider to be the pressureless dust). Determining the conditions for the existence of the stable CPs, we check their physical viability in both Einstein and Jordan frames. We also verify that in either of these frames, the evolution of the universe at the corresponding stable points matches with that given by the respective exact solutions we have found in an earlier work [S. Sur and A. S. Bhatia, arXiv:1611.00654 [gr-qc]]. We not only examine the regions of physical relevance in the phase-space when the coupling parameter is varied, but also demonstrate the evolution profiles of the cosmological parameters of interest along fiducial trajectories in the effectively noninteracting scenarios, in both Einstein and Jordan frames.

scholarly journals A dynamical system analysis of holographic dark energy models with different IR cutoff

2015 ◽  
Vol 30 (27) ◽  
pp. 1550134 ◽  
Author(s):  
Nilanjana Mahata ◽  
Subenoy Chakraborty
Keyword(s):  
Dynamical System ◽  
Dark Energy ◽  
System Analysis ◽  
Holographic Dark Energy ◽  
Holographic Model ◽  
Future Event ◽  
Dynamical Equations ◽  
Energy Models ◽  
Matter Energy ◽  
Future Event Horizon

The paper deals with a dynamical system analysis of the cosmological evolution of an holographic dark energy (HDE) model interacting with dark matter (DM) which is chosen in the form of dust. The infrared cutoff of the holographic model is considered as future event horizon or Ricci length scale. The interaction term between dark energy (DE) and DM is chosen of following three types: (i) proportional to the sum of the energy densities of the two dark components, (ii) proportional to the product of the matter energy densities and (iii) proportional to DE density. The dynamical equations are reduced to an autonomous system for the three cases and corresponding phase space is analyzed.

Phase-space analysis on interactions in dark energy models

2012 ◽  
Vol 72 (6) ◽  
Author(s):  
Yi Zhang ◽  
Hui Li ◽  
Yungui Gong ◽  
Zong-Hong Zhu
Keyword(s):  
Dark Energy ◽  
Phase Space ◽  
Phase Space Analysis ◽  
Space Analysis ◽  
Energy Models

scholarly journals Parameterizing Dark Energy Models and Study of Finite Time Future Singularities

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Tanwi Bandyopadhyay ◽  
Ujjal Debnath
Keyword(s):  
Dark Energy ◽  
Finite Time ◽  
State Parameter ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
Frw Model ◽  
The Universe ◽  
Theoretic Description ◽  
Friedmann Robertson Walker ◽  
Time Future

A review on spatially flat D-dimensional Friedmann-Robertson-Walker (FRW) model of the universe has been performed. Some standard parameterizations of the equation of state parameter of the dark energy models are proposed and the possibilities of finite time future singularities are investigated. It is found that certain types of these singularities may appear by tuning some parameters appropriately. Moreover, for a scalar field theoretic description of the model, it was found that the model undergoes bouncing solutions in some favorable cases.

scholarly journals Couplingq-Deformed Dark Energy to Dark Matter

2016 ◽  
Vol 2016 ◽  
pp. 1-20 ◽  
Author(s):  
Emre Dil
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Phase Space ◽  
Scalar Field ◽  
Dark Energy Model ◽  
Cosmological Parameters ◽  
Energy Model ◽  
Late Time ◽  
Acceleration Phase ◽  
Energy Models

We propose a novel coupled dark energy model which is assumed to occur as aq-deformed scalar field and investigate whether it will provide an expanding universe phase. We consider theq-deformed dark energy as coupled to dark matter inhomogeneities. We perform the phase-space analysis of the model by numerical methods and find the late-time accelerated attractor solutions. The attractor solutions imply that the coupledq-deformed dark energy model is consistent with the conventional dark energy models satisfying an acceleration phase of universe. At the end, we compare the cosmological parameters of deformed and standard dark energy models and interpret the implications.

scholarly journals Scalar field dark energy with a minimal coupling in a spherically symmetric background

2017 ◽  
Vol 27 (01) ◽  
pp. 1750173 ◽  
Author(s):  
Jiro Matsumoto
Keyword(s):  
Dark Energy ◽  
Solar System ◽  
Modified Gravity ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Minimal Coupling ◽  
Matter Coupling ◽  
Energy Models ◽  
Modified Gravity Theories ◽  
Quintessence Model

Dark energy models and modified gravity theories have been actively studied and the behaviors in the solar system have been also carefully investigated in a part of the models. However, the isotropic solutions of the field equations in the simple models of dark energy, e.g. quintessence model without matter coupling, have not been well investigated. One of the reason would be the nonlinearity of the field equations. In this paper, a method to evaluate the solution of the field equations is constructed, and it is shown that there is a model that can easily pass the solar system tests, whereas, there is also a model that is constrained from the solar system tests.

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