Presence Of Massive Scalar Field Research Articles

Decoupled quark stars relativistic models in the regime of self-interacting Brans–Dicke gravity

In this work, we generate two static anisotropic solutions for a sphere containing quark matter in the framework of self-interacting Brans–Dicke theory. For this purpose, we add an anisotropic source in the seed distribution and decouple the field equations through deformation in the radial metric function. As a result of this transformation, the field equations are disintegrated into two systems which separately include the effects of isotropic and anisotropic sources. The system related to the additional source is solved via the MIT bag model equation of state. We consider Tolman V spacetime and Karmarkar condition to formulate two solutions for the isotropic sector which are extended to the anisotropic domain via decoupling technique. The junction conditions at the boundary determine the unknown parameters in terms of mass and radius of the spherical object. We investigate the viability and stability of the constructed strange star models in the presence of massive scalar field corresponding to three strange star candidates: Her X-1, PSR J1614-2230 and 4U 1608-52. It is concluded that the anisotropic models are well-behaved as they fulfill the necessary requirements for lower as well as higher values of the decoupling parameter. • We generate two anisotropic spherical solutions with quark matter in self-interacting Brans–Dicke theory. • Viability and stability of the constructed strange star models are checked for three strange star candidates. • Anisotropic models are well-behaved for lower as well as higher values of the decoupling parameter.

Bianchi type-V Dark Energy Modified f(R,T) Gravity Model in the Presence of Massive Scalar Field in Lyra Geometry

Here, we investigate Bianchi type-V modified f(R,T) gravity cosmological models in Lyra geometry. To acquire the deterministic solution of the field equations with f(R,T) gravity based on Lyra geometry, we consider f(R,T)= f_1 (R)+f_2 (T), R indicates Ricci Scalar, T indicates trace of the energy momentum tensor in Lagrangian matter. Presence of Massive scalar field and Displacement vector of Lyra played an important role. The physical as well as the geometrical nature of the f(R,T) model is also discussed. HIGHLIGHTS In this present model of universe, we obtained that the universe starts with zero volume As in present observational data like CMB, BAO, La Supernona, our model is accelerating It is observed that the scalar field and kinetic energy both are non singular CDM is not satisfied in this model of universe GRAPHICAL ABSTRACT

Study of Frw Type Kaluza-Klein Domain Wall Cosmological Models in the Presence of Massive Scalar Field in a Modified Gravity

This article examines the physical behaviour of the Kaluza-Klein FRW type space-time with f(R,T) gravity proposed by Harko et al. (Phys. Rev. D 84:024020, 2011) in the presence of a massive scalar meson field. Here, ”R” stands for the Ricci tensor, while ”T” stands for the energy-momentum tensor’s trace. We employed the (i ) hybrid expansion law (Akarsu et al. JCAP, 01:022, 2014), (ii ) the variable deceleration parameter (Mishra et al. Int. J. Theor. Phys. 52:2546, 2013), and (iii ) the linearly varying deceleration parameter (Akarsu and Dereli. Int. J. Theor. Phys. 51:612, 2012) to solve the field equations. Additionally, we looked at some of the model’s physical and kinematic characteristics. Our models have been found to show a smooth transition from the universe’s early slowdown to its current acceleration, and the current value of the deceleration parameter is found to be reasonably consistent with the observational data. The early stages of the universe’s evolution will be better understood through the study of domain wall cosmological models.

Anisotropic minimally interacting dark energy models with cosmic strings and a massive scalar field

This paper deals with the construction of locally rotationally symmetric (LRS) Bianchi type-II (B-II) cosmological models obtained by solving Einstein field equations coupled with an attractive massive scalar field (MSF) when the source of gravitation is the mixture of cosmic string cloud and anisotropic dark energy (DE) fluid which are minimally interacting. We have obtained exact cosmological models by using (i) shear scalar is proportional to the scalar expansion of the space–time and (ii) a power-law relation between the average scale factor of the universe and the scalar field. Our models represent string cosmological model and DE model in the presence of MSF. Using our model, we determine cosmological parameters such as energy densities, deceleration parameter, statefinders and equation of state parameter. We, also, present the tension density and energy density of the string. We discuss the physical aspects of these cosmological parameters. It is observed that our models represent accelerated expansion phenomenon of our universe as confirmed by Supernova Ia experiment.

Kaluza–Klein minimally interacting dark energy model in the presence of massive scalar field

In this paper, our purpose is to discuss the dynamical aspects of Kaluza–Klein five-dimensional cosmological model filled with minimally interacting baryonic matter and dark energy (DE) in the presence of an attractive massive scalar field. We obtain a determinate solution of the Einstein field equations using (i) a relation between the metric potentials and (ii) a power law relation between the average scale factor of the universe and the massive scalar field. We have determined scalar field, matter energy density, DE density, equation of state (EoS) [Formula: see text], deceleration [Formula: see text] and statefinder [Formula: see text] parameters of our model. We also develop [Formula: see text]–[Formula: see text] phase, squared sound speed, statefinders and [Formula: see text]–[Formula: see text] planes in the evolving universe. It is observed that the EoS parameter exhibits quintom-like behavior from quintessence to phantom epoch by crossing the vacuum era of the universe. The squared speed of sound represents the instability of the model, whereas the [Formula: see text]–[Formula: see text] plane shows both thawing and freezing regions. The [Formula: see text]CDM limit is attained in both [Formula: see text]–[Formula: see text] and statefinder planes. We have also discussed the cosmological importance of the above parameters with reference to modern cosmology. It is found that the dynamics of these cosmological parameters indicate the accelerated expansion of the universe which is consistent with the current cosmological observations.

Kaluza-Klein dark energy model in Lyra manifold in the presence of massive scalar field

In this investigation we intend to study the dynamics of an anisotropic dark energy cosmological model in the presence of a massive scalar field in a modified Riemannian manifold proposed by Lyra (Math. Z. 54:52, 1951) in the background of a five dimensional Kaluza-Klein space time. We solve the Einstein field equations using some physically significant conditions and present a deterministic dark energy cosmological model. We use here the time dependent displacement vector field of the Lyra manifold. All the dynamical parameters of the model, namely, average Hubble parameter, anisotropy parameter, equation of state parameter, dark energy density, deceleration parameter and statefinders are evaluated for our model and their physical relevance to modern cosmology is discussed in detail.

Bianchi type-V dark energy cosmological model in general relativity in the presence of massive scalar field

In this paper, we discuss spatially homogeneous and anisotropic Bianchi type-V dark energy cosmological model in the presence of an attractive massive scalar field in general relativity. We have solved the field equations using (i) the shear scalar of the metric is proportional to the expansion scalar which results a relationship between metric potentials and (ii) a power law between the massive scalar field and the average scale factor. We have computed the cosmological parameters like dark energy density, equation of state parameter, skewness parameters, deceleration parameter and statefinder parameters of our dark energy model with massive strings and discussed their physical significance in the light of the recent scenario of accelerated expansion of the universe and cosmological observations.

Bianchi type-II modified holographic Ricci dark energy cosmological model in the presence of massive scalar field

This work is devoted to the investigation of spatially homogeneous and totally anisotropic Bianchi type-II cosmological model filled with pressure-less matter and anisotropic modified Ricci dark en...

Dynamics of perfect fluid cosmological model in the presence of massive scalar field in f ( R , T ) $f(R,T)$ gravity

In this paper, we are interested to investigate spatially homogeneous and totally anisotropic perfect cosmological model in the presence of an attractive massive scalar field in $f(R,T)$ gravity in the background of Bianchi type- $\mathit{III}$ space-time. Here $R$ is the Ricci scalar and $T$ is the trace of the energy momentum tensor. In order to solve the field equations, we have used (i) the expansion scalar of the space-time is proportional to the shear scalar which leads to a relationship between metric potentials and (ii) a power law between the scalar field and the average scale factor. We obtain a cosmological model of the universe with variable deceleration parameter. We have computed all the cosmological parameters of the model and discussed their physical importance.

Bianchi Type-III Cosmological Models in Lyra’s Geometry in the Presence of Massive Scalar Field

Spatially homogeneous and totally anisotropic Bianchi type-III cosmological models in the theory based on Lyra’s geometry in Gauss normal gauge in the presence of an attractive massive scalar field have been investigated. To get the deterministic model in terms of cosmic time, it has been assumed that the expansion scalar Θ in the models is proportional to the shear scalar σ. Two models, one with variable deceleration parameter and another with constant deceleration parameter have been discussed. To discuss the model with constant deceleration parameter, we have used the special law of variation for Hubble’s parameter proposed by (Berman Nuovo Cimento 74B, 184, 1983). The physical and geometrical properties of the models have been discussed. The energy conditions of the models are verified. It has been concluded that one of the universe models approaches to isotropy through the evolution of the universe, in some special cases.

Singularity-free RW viscous fluid cosmological models in presence of massive scalar fields

Singularity-free Robertson-Walker cosmological models (RWCM) are developed by considering the cosmic matter as composed of interacting viscous fluid (with zero bulk viscosity) and massive scalar (meson) field. Solutions are obtained for two different cases, viz., when the Hubble's parameterH is epoch independent and whenH is epoch dependent. A solution corresponding to RWCM with only the massive scalar field as the matter content is also presented. Essential physical behaviour of the models developed are discussed in detail.

Singularity-free RW viscous fluid cosmological models in presence of massive scalar fields

Singularity-free RW viscous fluid cosmological models in presence of massive scalar fields

A plane symmetric solution of Einstein's field equations of general relativity containing zero-rest-mass scalar fields

An exact static solution of Einstein's field equations of general relativity in the presence of zero-rest-mass scalar fields has been obtained when both the metric tensor gijand the zero-rest-mass scalar field φexhibit plane symmetry in the sense of Taub [9]. Our solution generalizes the empty space-time solution with plane symmetry previously obtained by Taub to the situation when static zero-rest-mass scalar fields are present. The static plane symmetric solutoins of Einstein's field equations in the presence of massive scalar fields, and the difference between the massless and non-massless scalar fields are being investigated, and will be published separately later on. We also hope to discuss non-static plane symmetric solutions of Einstein's field equations in the presence of scalar fields in future.