scholarly journals Could the Lyra manifold be the hidden source of the dark energy?

2017 ◽  
Vol 14 (04) ◽  
pp. 1750063 ◽  
Author(s):  
Kangujam Priyokumar Singh ◽  
Mahbubur Rahman Mollah
Keyword(s):  
Dark Energy ◽  
Accelerated Expansion ◽  
Accelerating Universe ◽  
Type I ◽  
Lyra Manifold ◽  
Expansion Behavior ◽  
Rotationally Symmetric ◽  
Present Universe ◽  
Bianchi Type I Universe ◽  
The Universe

In the course of investigation of our present universe by considering the five-dimensional locally rotationally symmetric (LRS) Bianchi type-I universe with time-dependent deceleration parameters in Lyra manifold, it is excitingly found that the geometry itself of Lyra manifold behaves and consistent with present observational findings for accelerating universe. The behavior of the universes and their contribution to the process of evolution are examined. While studying their physical, dynamical and kinematical properties for different cases, it is found that this model is a new and viable form of model universe containing dark energy. It will be very helpful in explaining the present accelerated expansion behavior of the universe.

The late cosmic acceleration and the coincidence problem in Bianchi type I Universe

2019 ◽  
Vol 34 (29) ◽  
pp. 1950239 ◽  
Author(s):  
Ruslan K. Muharlyamov ◽  
Tatiana N. Pankratyeva
Keyword(s):  
Special Kind ◽  
Cosmic Acceleration ◽  
Accelerated Expansion ◽  
Type I ◽  
Coincidence Problem ◽  
Linear Interaction ◽  
Proposed Model ◽  
Rotationally Symmetric ◽  
Present Universe ◽  
Bianchi Type I Universe

In locally rotationally symmetric (LRS) Bianchi-I spacetime, we are considering a special kind of a scale factor, called the hybrid expansion law (HEL). The HEL provides a description of the transition from deceleration to cosmic acceleration. A non-minimal interaction between dark energy (DE) and dark matter (DM) allows to combine the transition from matter dominance to the era of the DE dominance with the transition from decelerated to accelerated expansion. In the proposed model, the linear interaction of the two components solves the coincidence problem of our present Universe. We present examples of numerical values of the HEL parameters compatible with the constructed model and the observational data.

Pilgrim dark energy models in fractal universe

2016 ◽  
Vol 26 (06) ◽  
pp. 1750049 ◽  
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
Ines G. Salako ◽  
Faiza Gulshan
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
Accelerated Expansion ◽  
Freezing And Thawing ◽  
Eos Parameter ◽  
Pilgrim Dark Energy ◽  
Energy Models ◽  
Expansion Behavior ◽  
The Universe

We discuss the cosmological implications of interacting pilgrim dark energy (PDE) models (with Hubble, Granda–Oliveros and generalized ghost cutoffs) with cold dark matter ([Formula: see text]CDM) in fractal cosmology by assuming the flat universe. We observe that the Hubble parameter lies within observational suggested ranges while deceleration parameter represents the accelerated expansion behavior of the universe. The equation of state (EoS) parameter ([Formula: see text]) corresponds to the quintessence region and phantom region for different cases of [Formula: see text]. Further, we can see that [Formula: see text]–[Formula: see text] (where prime indicates the derivative with respect to natural logarithmic of scale factor) plane describes the freezing and thawing regions and also corresponds to [Formula: see text] limit for some cases of [Formula: see text] (PDE parameter). It is also noted that the [Formula: see text]–[Formula: see text] (state-finder parameters) plane corresponds to [Formula: see text] limit and also shows the Chaplygin as well as phantom/quintessence behavior. It is observed that pilgrim dark energy models in fractal cosmology expressed the consistent behavior with recent observational schemes.

scholarly journals Dynamical Properties of Dark Energy Models in Fractal Universe

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1174
Author(s):  
Muhammad Umair Shahzad ◽  
Ayesha Iqbal ◽  
Abdul Jawad
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Accelerating Universe ◽  
Statefinder Parameters ◽  
Om Diagnostic ◽  
Energy Models ◽  
Expansion Of The Universe ◽  
Dynamical Properties ◽  
The Universe

In this paper, we consider the flat FRW spacetime filled with interacting dark energy and dark matter in fractal universe. We work with the three models of dark energy named as Tsallis, Renyi and Sharma–Mittal. We investigate different cosmological implications such as equation of state parameter, squared speed of sound, deceleration parameter, statefinder parameters, ω e f f - ω e f f ´ (where prime indicates the derivative with respect to ln a , and a is cosmic scale factor) plane and Om diagnostic. We explore these parameters graphically to study the evolving universe. We compare the consistency of dark energy models with the accelerating universe observational data. All three models are stable in fractal universe and support accelerated expansion of the universe.

The Mimetic Matter in LRS Bianchi Type-I Model

2021 ◽  
Author(s):  
Ertan Gudekli ◽  
E. Demir
Keyword(s):  
Bianchi Type ◽  
State Parameter ◽  
Relativity Theory ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Rotationally Symmetric ◽  
Bianchi Type I Universe ◽  
Expansion Of The Universe ◽  
The Universe

This paper deals with the Locally rotationally symmetric (LRS) Bianchi type-I universe model in Mimetic Gravity Theory assuming it an extended form of General Relativity Theory. It was proclaimed as a conformal transformation of the Einstein-Hilbert action from Einstein frame to Jordon frame. At the outset, we have proposed a potential function on account of clarifying the expansion of our universe by considering the general solutions of the field equations that originate from the action of the theory including the Lagrange multipliers. Lastly, after having been achieved the general equation of the state parameter ω, we discussed whether the result corresponds to some fluids illuminating the expansion of the Universe or not.

Ghost dark energy models in Bianchi I cosmologies with modified gravity

2014 ◽  
Vol 92 (2) ◽  
pp. 168-172 ◽  
Author(s):  
V. Fayaz ◽  
H. Hossienkhani ◽  
A. Aghamohammadi ◽  
M. Amirabadi
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
General Scheme ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Type I ◽  
Field Equations ◽  
Ghost Dark Energy ◽  
Expansion Of The Universe ◽  
The Universe

A ghost dark energy model has been recently put forward to explain the current accelerated expansion of the universe. In this model, we develop the general scheme for modified f(R) gravity reconstruction from realistic anisotropic Bianchi type I cosmology. Power-law volumetric expansion is used to obtain exact solutions of the field equations. We discuss the physical behavior of the solutions and anisotropy behavior of the fluid, the expansion parameter, and the model in future evolution of the universe. We reconstruct corresponding f(R) gravities and obtain the equation of state parameter. We show that the corresponding f(R) gravity of the ghost dark energy model can behave like phantom or quintessence of the selected models that describe accelerated expansion of the universe.

scholarly journals Scenario of accelerated universe expansion under exposure to entropic forces related to with the entropies of Barrow and Tsallis−Cirto

2021 ◽  
Vol 50 ◽  
pp. 80-103
Author(s):  
Aleksandr Vladimirovich Kolesnichenko ◽  
Mikhail Yakovlevich Marov
Keyword(s):  
Dark Energy ◽  
Accelerated Expansion ◽  
Accelerating Universe ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Holographic Storage ◽  
Adiabatic Evolution ◽  
Isotropic Universe ◽  
Modified Equations ◽  
The Universe

In the work within the framework of "entropic cosmology", the scenario of the cosmological accelerated expansion of a flat, homogeneous and isotropic Universe under the influence of entropic forces is considered without the concept of dark energy a hypothetical medium with negative pressure. Assuming that the horizon of the Universe has its own temperature and entropy, which arises during the holographic storage of information on the screen of the horizon surface, the entropy models of the Universe associated with the BekensteinHawking entropy and the non-extensive Barrow and Tsallis–Cirto entropies are considered. The modified equations of acceleration and continuity of Friedman with governing power terms having an entropic nature are derived both within the framework of Einstein's general theory of relativity and on the basis of a thermodynamic approach that allows modeling the non-adiabatic evolution of the Universe. At the same time, models based on nonextensive entropies predict the existence of both a decelerating and accelerating Universe.

scholarly journals LOCALLY ROTATIONALLY SYMMETRIC BIANCHI TYPE-I COSMOLOGICAL MODEL IN f(T) GRAVITY: FROM EARLY TO DARK ENERGY DOMINATED UNIVERSE

2014 ◽  
Vol 23 (01) ◽  
pp. 1450004 ◽  
Author(s):  
M. E. RODRIGUES ◽  
I. G. SALAKO ◽  
M. J. S. HOUNDJO ◽  
J. TOSSA
Keyword(s):  
Dark Energy ◽  
Cosmological Model ◽  
Dark Energy Model ◽  
Bianchi Type ◽  
Rotational Symmetry ◽  
Type I ◽  
Bianchi Type I ◽  
Reconstruction Scheme ◽  
Rotationally Symmetric ◽  
The Universe

We study the locally rotational symmetry Bianchi type-I dark energy model in the framework of f(T) theory of gravity, where T denotes the torsion scalar. A viable cosmological model is undertaken and the isotropization of this latter is checked, yielding a result that reflects the real evolution of our universe. Moreover, still in the anisotropic optic, a more complicated f(T) model is obtained from the cosmological reconstruction scheme and the analysis shows that the universe is more anisotropic at the beginning if the terms of higher order in T are not considered. This means that the nonlinear model should be favored by observational data.

scholarly journals Toy Models of Universe with an Effective VaryingΛ-Term in Lyra Manifold

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Martiros Khurshudyan
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Accelerated Expansion ◽  
Observational Constraints ◽  
Constant Deceleration Parameter ◽  
Expansion Phase ◽  
Lyra Manifold ◽  
New Form ◽  
Transit Universe ◽  
The Universe

Research on the accelerated expansion of our Universe captures a lot of attention. The dark energy (DE) is a way to explain it. In this paper we will consider scalar field quintessence DE withωDE>-1EoS, where the dynamics of the DE models related to the dynamics of the scalar field. We are interested in the study of the behavior of the Universe in the presence of interacting quintessence DE models in Lyra manifold with a varyingΛt. In a considered framework we also would like to propose a new form forΛt. We found that the models correspond to the transit Universe, which will enter the accelerated expansion phase and will remain there with a constant deceleration parameterq. We found also that theΛtis a decreasing function which takes a small positive value withΩm≠0andΩQ→constdominatingΩmin the old Universe. Observational constraints are applied and causality issue viaCS2is discussed as a possible way to either reject or accept the models.

scholarly journals Stability of the Universe Model Coupled with Phantom and Tachyon Fields

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
M. Sharif ◽  
Saadia Mumtaz
Keyword(s):  
Critical Points ◽  
Bianchi Type ◽  
Dynamical Analysis ◽  
Type I ◽  
Universe Model ◽  
Cosmic Expansion ◽  
Rotationally Symmetric ◽  
Coupled Field ◽  
Bianchi Type I Universe ◽  
The Universe

In this paper, we study the phase space analysis of locally rotationally symmetric Bianchi type I universe model by taking interactions between dark matter and scalar field models. We define normalized dimensionless variables to develop an autonomous system of equations. We also find the corresponding critical points in order to study the dynamics of the system. The dynamical analysis indicates that all the critical points correspond to accelerated cosmic expansion for tachyon coupled field. We observe that positive values of m provide more stable future attractors as compared to its negative values. We also analyze the behavior of power-law scale factor which shows different cosmological phases. It is found that the region for decelerated expansion gets larger for the phantom coupled matter by increasing m while this region decreases for tachyon coupled field.

scholarly journals Effects of anisotropy on the sign-changeable interacting Tsallis holographic dark energy

2019 ◽  
Vol 35 (09) ◽  
pp. 2050053 ◽  
Author(s):  
M. Abdollahi Zadeh ◽  
A. Sheykhi ◽  
Kazuharu Bamba ◽  
H. Moradpour
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Holographic Dark Energy ◽  
Model Parameters ◽  
Type I ◽  
Infra Red ◽  
Bianchi Type I Universe ◽  
Spatially Homogeneous ◽  
The Universe ◽  
Comprehensive Study

We consider a spatially homogeneous and anisotropic Bianchi type-I universe which is filled by pressureless dark matter (DM) and Tsallis holographic dark energy (THDE). We assume the two dark components of the universe are interacting with each other throughout a sign-changeable mutual interaction term. Various infra-red (IR) cutoffs are studied, and it is obtained that all models display classical instability by themselves at the future [Formula: see text]. Moreover, we find out that some models can cross the phantom line. In order to have a more comprehensive study, the statefinder diagnostic and the [Formula: see text] plane are also investigated showing that the model parameters significantly affect the evolution trajectories in the [Formula: see text] and [Formula: see text] planes.

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