DILATION DARK MATTER IN VAIDYA–de SITTER SPACETIME

The exterior of a relativistic star can be modeled with the Vaidya radiating metric. It is started from the generalized Vaidya metric that allows a type II fluid and studied the conditions of generating new analytical solutions of the Einstein's field equations. It is shown that the mass parameter solution gives the classical de Sitter universe in the static case and the extended de Sitter metric coupled with a dilation scalar field in the time-dependent case. It is concluded that in the time-dependent case the atmosphere of a relativistic star consists on an anisotropic string fluid coupled with a dark matter null fluid and interpreted the scalar field as the particle that produces the dark matter.

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Dynamics of scalar potentials in theory of gravity

Canadian Journal of Physics ◽

10.1139/cjp-2018-0566 ◽

2019 ◽

Vol 97 (8) ◽

pp. 880-894

Author(s):

M. Zubair ◽

Farzana Kousar ◽

Saira Waheed

Keyword(s):

Scalar Field ◽

Field Potential ◽

Graphical Analysis ◽

Chaplygin Gas ◽

Field Potentials ◽

De Sitter ◽

Field Equations ◽

Barotropic Fluid ◽

First Case ◽

De Sitter Universe

In this paper, we explore the nature of scalar field potential in [Formula: see text] gravity using a well-motivated reconstruction scheme for flat Friedmann–Robertson–Walker (FRW) geometry. The beauty of this scheme lies in the assumption that the Hubble parameter can be expressed in terms of scalar field and vice versa. Firstly, we develop field equations in this gravity and present some general explicit forms of scalar field potential via this technique. In the first case, we take the de Sitter universe model and construct some field potentials by taking different cases for the coupling function. In the second case, we derive some field potentials using the power law model in the presence of different matter sources like barotropic fluid, cosmological constant, and Chaplygin gas for some coupling functions. From graphical analysis, it is concluded that using some specific values of the involved parameters, the reconstructed scalar field potentials are cosmologically viable in both cases.

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TORSION, DIRAC FIELD, DARK MATTER AND DARK RADIATION

International Journal of Modern Physics A ◽

10.1142/s0217751x07034076 ◽

2007 ◽

Vol 22 (04) ◽

pp. 835-850 ◽

Cited By ~ 10

Author(s):

PRASANTA MAHATO

Keyword(s):

Dark Matter ◽

Scalar Field ◽

Lagrange Multipliers ◽

Lagrangian Density ◽

Dirac Field ◽

De Sitter ◽

Field Equations ◽

Cartan Geometry ◽

Dark Radiation

The role of torsion and a scalar field ϕ in gravitation, especially, in the presence of a Dirac field in the background of a particular class of the Riemann–Cartan geometry is considered here. Recently, a Lagrangian density with Lagrange multipliers has been proposed by the author which has been obtained by picking some particular terms from the SO (4, 1) Pontryagin density, where the scalar field ϕ causes the de Sitter connection to have the proper dimension of a gauge field. In this paper the scalar field has been linked to the dimension of the Dirac field. Here we get the field equations for the Dirac field and the scalar field in such a way that both of them appear to be mutually noninteracting. In this scenario the scalar field appears to be a natural candidate for the dark matter and the dark radiation.

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FERMIONIC AND SCALAR FIELDS AS SOURCES OF INTERACTING DARK MATTER–DARK ENERGY

International Journal of Modern Physics D ◽

10.1142/s0218271811020500 ◽

2011 ◽

Vol 20 (13) ◽

pp. 2543-2558 ◽

Cited By ~ 2

Author(s):

SAMUEL LEPE ◽

JAVIER LORCA ◽

FRANCISCO PEÑA ◽

YERKO VÁSQUEZ

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Scalar Field ◽

Analytical Solution ◽

Scalar Fields ◽

Nonminimal Coupling ◽

Field Equations ◽

Fermionic Field ◽

Minimal Coupling ◽

Constant Type

From a variational action with nonminimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a Friedmann–Lemaître–Robertson–Walker (FLRW) metric, the equations lead directly to a cosmological model consisting of two interacting fluids, where the scalar field fluid is interpreted as dark energy and the fermionic field fluid is interpreted as dark matter. Several cases were studied analytically and numerically. An important feature of the non-minimal coupling is that it allows crossing the barrier from a quintessence to phantom behavior. The insensitivity of the solutions to one of the parameters of the model permits it to find an almost analytical solution for the cosmological constant type of universe.

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Averaging generalized scalar field cosmologies II: locally rotationally symmetric Bianchi I and flat Friedmann–Lemaître–Robertson–Walker models

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09230-5 ◽

2021 ◽

Vol 81 (6) ◽

Author(s):

Genly Leon ◽

Sebastián Cuéllar ◽

Esteban González ◽

Samuel Lepe ◽

Claudio Michea ◽

...

Keyword(s):

Scalar Field ◽

Nonlinear Dynamical Systems ◽

Perturbation Parameter ◽

Time Dependent ◽

Late Time ◽

De Sitter ◽

Time Dynamics ◽

Locally Rotationally Symmetric ◽

Bianchi I ◽

Rotationally Symmetric

AbstractScalar field cosmologies with a generalized harmonic potential and a matter fluid with a barotropic equation of state (EoS) with barotropic index $$\gamma $$ γ for the locally rotationally symmetric (LRS) Bianchi I and flat Friedmann–Lemaître–Robertson–Walker (FLRW) metrics are investigated. Methods from the theory of averaging of nonlinear dynamical systems are used to prove that time-dependent systems and their corresponding time-averaged versions have the same late-time dynamics. Therefore, the simplest time-averaged system determines the future asymptotic behavior. Depending on the values of $$\gamma $$ γ , the late-time attractors of physical interests are flat quintessence dominated FLRW universe and Einstein-de Sitter solution. With this approach, the oscillations entering the system through the Klein–Gordon (KG) equation can be controlled and smoothed out as the Hubble parameter H – acting as time-dependent perturbation parameter – tends monotonically to zero. Numerical simulations are presented as evidence of such behavior.

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Nonlinear Schrödinger-type formulation of scalar field cosmology: Two barotropic fluids and exact solutions

Modern Physics Letters A ◽

10.1142/s0217732320501576 ◽

2020 ◽

Vol 35 (19) ◽

pp. 2050157

Author(s):

Chonticha Kritpetch ◽

Jarunee Sanongkhun ◽

Pichet Vanichchapongjaroen ◽

Burin Gumjudpai

Keyword(s):

Scalar Field ◽

Exact Solutions ◽

Time Dependent ◽

Frw Cosmology ◽

Dependent Case ◽

Nonlinear Schrödinger ◽

Barotropic Fluids ◽

Scalar Field Cosmology ◽

Formulation Variables ◽

Canonical Scalar Field

Time-independent nonlinear Schrödinger-type (NLS) formulation of FRW cosmology with canonical scalar field is considered in the case of two barotropic fluids. We derived Friedmann formulation variables in terms of NLS variables. Seven exact solutions found by D’Ambroise [Ph.D. thesis, arXiv:1005.1410 ] and one new found solution are explored and tested in cosmology. The result suggests that time-independent NLS formulation of cosmology case should be upgraded to the time-dependent case.

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Interacting quintessence in light of generalized uncertainty principle: cosmological perturbations and dynamics

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09362-8 ◽

2021 ◽

Vol 81 (7) ◽

Author(s):

Andronikos Paliathanasis ◽

Genly Leon ◽

Wompherdeiki Khyllep ◽

Jibitesh Dutta ◽

Supriya Pan

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Uncertainty Principle ◽

Generalized Uncertainty Principle ◽

Background Level ◽

De Sitter ◽

Field Equations ◽

General Behaviour ◽

Wide Range ◽

Coupling Parameters

AbstractWe consider a cosmological scenario endowed with an interaction between the universe’s dark components – dark matter and dark energy. Specifically, we assume the dark matter component to be a pressure-less fluid, while the dark energy component is a quintessence scalar field with Lagrangian function modified by the quadratic Generalized Uncertainty Principle. The latter modification introduces new higher-order terms of fourth-derivative due to quantum corrections in the scalar field’s equation of motion. Then, we investigate asymptotic dynamics and general behaviour of solutions of the field equations for some interacting models of special interests in the literature. At the background level, the present interacting model exhibits the matter-dominated and de Sitter solutions which are absent in the corresponding quintessence model. Furthermore, to boost the background analysis, we study cosmological linear perturbations in the Newtonian gauge where we show how perturbations are modified by quantum corrected terms from the quadratic Generalized Uncertainty Principle. Depending on the coupling parameters, scalar perturbations show a wide range of behavior.

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Fuzzy dark matter black holes and droplets

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09552-4 ◽

2021 ◽

Vol 81 (8) ◽

Author(s):

D. Batic ◽

D. Asem Abuhejleh ◽

M. Nowakowski

Keyword(s):

Black Holes ◽

Black Hole ◽

Dark Matter ◽

Black Hole Solution ◽

Mass Parameter ◽

Radial Pressure ◽

Momentum Tensor ◽

Anisotropic Fluid ◽

De Sitter ◽

Hole Model

AbstractWe consider the possibility of having Dark Matter (DM) black holes motivated by the Einasto density profile. This generalizes both the noncommutative mini black hole model and allows DM to enter as the matter constituent which makes up the black hole. We show that it is possible to construct a black hole solution for each value of the Einasto index and for different values of the mass parameter, provided that the we work with the energy–momentum tensor of an anisotropic fluid. In particular, we achieve that by first considering the equation of state (EOS) $$p_r=-\rho $$ p r = - ρ . It turns out that the corresponding black hole solution exhibits a horizon structure similar to that of a Reissner–Nordström black hole and the central singularity is replaced by a regular de Sitter core. We also show that if the previous EOS is replaced by a nonlocal one, it is possible to construct a self-gravitating fuzzy DM droplet but also in this case, the radial pressure is negative. Finally, we contemplate scenarios of different dark matter black holes with moderate mass values which could have formed in galaxies. In particular, we probe the possibility whether such black holes could also be the central galactic objects.

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Global existence of the self-interacting scalar field in the de Sitter universe

Journal of Mathematical Physics ◽

10.1063/1.5082653 ◽

2019 ◽

Vol 60 (5) ◽

pp. 051503 ◽

Cited By ~ 4

Author(s):

Karen Yagdjian

Keyword(s):

Scalar Field ◽

Global Existence ◽

The Self ◽

De Sitter ◽

Sitter Universe ◽

De Sitter Universe

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Dynamical system analysis for DBI dark energy interacting with dark matter

Modern Physics Letters A ◽

10.1142/s0217732315500091 ◽

2015 ◽

Vol 30 (02) ◽

pp. 1550009 ◽

Cited By ~ 10

Author(s):

Nilanjana Mahata ◽

Subenoy Chakraborty

Keyword(s):

Dynamical System ◽

Dark Matter ◽

Dark Energy ◽

Scalar Field ◽

System Analysis ◽

Einstein Field Equation ◽

Field Equations ◽

Cosmological Scenario ◽

Kinetic Energy Term ◽

Autonomous Dynamical System

A dynamical system analysis related to Dirac–Born–Infeld (DBI) cosmological model has been investigated in this present work. For spatially flat FRW spacetime, the Einstein field equation for DBI scenario has been used to study the dynamics of DBI dark energy interacting with dark matter. The DBI dark energy model is considered as a scalar field with a nonstandard kinetic energy term. An interaction between the DBI dark energy and dark matter is considered through a phenomenological interaction between DBI scalar field and the dark matter fluid. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables. The potential of the DBI scalar field is assumed to be exponential. Finally, critical points are determined, their nature have been analyzed and corresponding cosmological scenario has been discussed.

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