Bianchi type-II,VIII, and IX cosmological models with matter and electromagnetic fields

We present analytic solutions of the Einstein-Maxwell equations for cosmological models of LRS Bianchi type-II, VIII, and IX. The solutions represent anisotropic universes with source-free electromagnetic fields and perfect fluids matter satisfying the equation of state that is a function of the cosmic-time. Some physical properties of the models have been discussed.     

Exact bianchi type-II,VIII and IX cosmological models in scale-covariant theory of gravitation

Exact Bianchi types-II, VIII and IX cosmological models are obtained in the scale covariant theory of gravitation. Some physical and geometrical properties of the models are studied.     

Comment on stiff matter solutions in cosmological models based on Lyra's manifold

The optical light variation of the nucleus of the galaxy NGC 4151 was monitored mainly using the 74 inch telescope of the Helwan Observatory, Egypt.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Bianchi type-II,VIII, and IX cosmologies with conformally-invariant scalar field and electromagnetic fields

In the expansive nondecelerative universe creation of matter happens as a result of a fundamental relationship and mutual compatibility of the field and matter.     

Exact Bianchi type VIo cosmological models with matter and an electromagnetic field

Self-similar solution for isothermal flows driven by an expanding piston are investigated in the presence of magnetic field. The total energy of the flow between the shock and the piston is taken to be dependent on time obeying a power law. The shock is assumed to be strong and propagating into a perfect gas at rest with non uniform density and magnetic field.     

Bianchi type-II, VIII & IX perfect fluid magnetized cosmological models in Brans-Dicke theory of gravitation

Spatially homogeneous Bianchi type-II, VIII & IX charged perfect fluid cosmological models in Brans-Dicke theory of gravitation are obtained and presented. Various physical and geometrical features of the models are also discussed.     

An anisotropic cosmological model in Lyra's manifold

A spatially homogeneous and anisotropic cosmological model in Lyra's manifold is obtained when the source of the gravitational field is a perfect fluid with pressure equal to energy density and the metric is of Bianchi type-I. Various physical and geometrical properties of the model have also been discussed.     

Exact Bianchi-type VIII and IX models in the presence of zero-mass scalar fields

Exact Bianchi-type VIII and IX models in the presence of zero-mass scalar fields are presented, when the source of the gravitational field is a perfect fluid withP=. Some physical and geometrical properties of the models are also discussed.     

Early cosmological models in Lyra's geometry

A spatially homogeneous and isotropic Robertson-Walker model withzero-curvature of the universe is studied within the frame-work of Lyra'smanifold. The gauge-function in Lyra's manifold is taken to betime-dependent. Exact solutions of Einstein equations are obtained for twodifferent early phases of the universe viz. Inflationary phase andradiation-dominated phase by using `gamma-law' equation of statep = ( - 1) . The -index, describing the material content,varies continuously with cosmic time so that in the course of itsevolution, the universe goes through a transition from an inflationaryphase to a radiation-dominated phase. The physical properties of themodels are also discussed.     

A static conformally flat cosmological model in Lyra's manifold

A static conformally flat spherically-symmetric perfect fluid cosmological model based on Lyra's modified Riemannian geometry is proposed. Some properties of the model are discussed.     

Exact Brans-Dicke-Bianchi types-II,VIII, and IX stiff matter solutions

Exact solutions of the Brans-Dicke field equations of Bianchi types-II, VIII, and IX are derived. The solutions represent locally rotationally symmetric universes with stiff matter content.     

Exact Brans-Dicke bianchi type-I vacuum solutions with a cosmological constant

Exact cosmological solutions of the vacuum Brans-Dicke field equations are derived. The solutions are the anisotropic generalizations of the isotropic de Sitter solutions of the general theory of relativity.     

Bianchi type-II cosmological models in the presence of zero-mass scalar fields

The exact Bianchi type-II vacuum- and stiff-fluid cosmological models, in the presence of zero-mass scalar fields, are obtained. Some physical properties of the models are also discussed.     

Bianchi type-II,VIII, and IX in certain new theories of gravitation

Bianchi type-II, VIII, and IX models have been investigated in scalar-tensor theories developed by Saez (1985), Saez and Ballester (1985), and Lau and Prokhovnik (1986) (under the assumption of a certain relationship between the cosmological term and the scalar field ). The dynamical behaviour of these models has been studied.     

Exact Bianchi type-II cosmological vacuum solutions in Jordan Brans-Dicke theory

Exact solutions for Bianchi type-II cosmological model in the Jordan Brans-Dicke scalar-tensor theory of gravilation are obtained. We discuss the behaviour of these solutions and compare them with others recently published.Supported in part by DGICSA SEP grant C90-03-0347.     

Tilted bianchi type v bulk viscous cosmological models in general relativity

Conformally flat tilted Bianchi type V cosmological models in presence of a bulk viscous fluid and heat flow are investigated. The coefficient of bulk viscosity is assumed to be a power function of mass density. Some physical andgeometric aspects of the models are also discussed.     

Vacuum bianchi type-V cosmological models in Ross and Dunn scalar-tensor theories of gravitation

It is shown that the relativistic analogues of vacuum Bianchi type-V cosmological models, in the scalar-tensor theories of gravitation proposed by Ross and Dunn, do not exist.     

Exact Bianchi type-I cosmological model with matter in Brans-Dicke theory

In this paper an exact solution of the Brans-Dicke field equations in the presence of stiff matter is obtained for the Bianchi type-I cosmological space-time. The new solution represents an anisotropic homogeneous cosmological model which tends to anisotropic expansion. The behaviour of the solution near the singularities and late stages of the expansion is discussed.     

Exact Bianchi-type VIII and IX models in the presence of the self-creation theory of cosmology

Exact Bianchi-type VIII and IX models in the presence of Barber's second self-creation theory of cosmology are presented, when the source of the gravitational field is a perfect fluid withP=. Some physical and geometrical properties of the models are discussed.