共查询到20条相似文献，搜索用时 31 毫秒
1.
Inhomogeneous universes filled with co-moving stiff perfect fluid and radiation have been derived. Most of the models contain as particular cases exact homogeneous universes of Bianchi type-VI
h
. Some physical behaviours of the models have been discussed. 相似文献
2.
Families of inhomogeneous models filled with a stiff perfect fluid and radiation have been derived in which there is no flow of total momentum. The models are the generalizations of those of Bianchi Type VI
h
and are discussed for some particular forms of the arbitrary functions appearing in them. 相似文献
3.
In this paper, we have investigated Bianchi type VI h , II and III cosmological model with wet dark fluid in scale invariant theory of gravity, where the matter field is in the form of perfect fluid and with a time dependent gauge function (Dirac gauge). A non-singular model for the universe filled with disorder radiation is constructed and some physical behaviors of the model are studied for the feasible VI h (h=1) space-time. 相似文献
4.
String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VIh metric in the frame work of general relativity. The field equations are solved for massive string cloud in presence of bulk
viscosity. A general linear equation of state of the cosmic string tension density with the proper energy density of the universe
is considered. The physical and kinematical properties of the models have been discussed in detail and the limits of the anisotropic
parameter responsible for different phases of the universe are explored. 相似文献
5.
C. Lozanovski 《Astrophysics and Space Science》2014,351(1):371-376
A class of purely magnetic diagonal Bianchi type VI h Cosmologies is investigated. If the energy-momentum tensor is specialized to that of a perfect fluid with (non-zero) heat-flux, with respect to the co-moving fluid 4-velocity, then the only solution is of Bianchi type V and un-physical. Further, it is shown that if certain metric functions are functionally related then the spacetime is conformally flat. Unfortunately, all these results (somewhat indirectly) invalidate a claim by Kumar and Srivastava of finding a non-conformally flat purely magnetic diagonal Bianchi type V cosmology. Finally, we consider non-zero anisotropic pressure in place of non-zero heat flux. It is shown that these spacetimes are necessarily Bianchi type VI 0. We highlight the fact that there is a known solution that generalizes the purely magnetic perfect fluid Wylleman-Van den Bergh spacetime. Physical properties of this solution are discussed. 相似文献
6.
We discuss spatially homogeneous and anisotropic Bianchi type VI
0 cosmological model with anisotropic fluid and magnetic field. The energy-momentum tensor consists of anisotropic fluid with
anisotropic EoS and a uniform magnetic field of energy density ρ
B
. Exact solution of the field equations is obtained by using the condition that expansion is proportional to the shear scalar.
We focus on the future evolution of the model both in the presence and absence of magnetic field. In particular, we address
the question whether these models approach to isotropy. 相似文献
7.
Shri Ram 《Astrophysics and Space Science》1984,104(1):151-155
An exact solution of Einstein's equations corresponding to the conformally invariant scalar field with tracefree energy-momentum tensor as source is obtained in Bianchi type VI0 class of metrics. The solution represents a spatially homogeneous but anisotropy universe which admits anisotropic expansions. Some properties of the cosmological model are discussed. 相似文献
8.
Vacuum Bianchi type V and VI0 cosmological models obtained in a new scalar-tensor theory of gravitation proposed by Schmidtet al. Some physical properties of these models are also discussed. 相似文献
9.
Bianchi type I, III, V, VI0, and Kantowski-Sachs type models have been investigated in a scalar tensor theory developed by Saez and Ballester (1985) and Saez (1985). The dynamical behaviour of the models has also been analyzed. 相似文献
10.
In this paper, we have investigated Bianchi type VI h cosmological model filled with perfect fluid in the framework of f(R,T) gravity, where R is the Ricci scalar and T is the trace of the energy-momentum tensor proposed by Harko et al. (Phys. Rev. D 84:024020, 2011). We have obtained the cosmological models by solving the field equations. Some physical behaviors of the model are also studied. 相似文献
11.
We present exact solutions of a Bianchi type VI0 viscous fluid cosmological model. It is a generalization of the model proposed by Banerjee and Santos (1983) for Bianchi type I. 相似文献
12.
The problem of perfect fluid distribution in spatially homogeneous and anisotropic Bianchi type VI0 space-time is considered in a scalar tensor theory of gravitation proposed by Saez and Ballester (1985). Exact solutions
of the field equations are derived when the metric potentials are functions of cosmic time only. Some physical and geometrical
properties of the solutions are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
D. Lorenz-Petzold 《Journal of Astrophysics and Astronomy》1985,6(3):137-144
We derive some new exact 7-dimensional cosmological solutions |R⊗ I ⊗N, whereN = I, II, VI0, VII0, VIII and IX are the various 3-dimensional Bianchi models. The solutions given are higher-dimensional generalizations of
the mixmaster cosmologies. There is a strong influence of the extra spacesN, which results in a fundamental change of the 3-dimensional cosmology. 相似文献
14.
We present an exact solution of the Brans-Dicke equations for cosmological models of Bianchi type VI0 with stiff matter. The solution represents anisotropic universe which has its analogy in Einstein's theory. The corresponding result for a plane symmetry Bianchi type I model is obtained as a special case. 相似文献
15.
The paper considers a homogeneous Bianchi type II universe. Under each of the conditionsC
hijk
C
hijk
=0 and*
C
hijk
C
hijk
=0 different types of models have been studied and their physical and kinematical properties have been discussed. 相似文献
16.
J. A. Belinchón 《Astrophysics and Space Science》2014,349(1):501-527
In order to study how the gravitational and the cosmological constants, G, Λ may vary, we consider two theoretical frameworks which are, a modification of the General Relativity and several scalar models (the standard, non-interacting and interacting models and their respective modifications to allow a G varying). We find exact self-similar solutions for the geometry Bianchi VI h , (that is, the models: III, VI0, and VI h ,). Some physical and geometrical properties of the models are also discussed and we compare the obtained theoretical results with the current observational data. In the first of the theoretical models, we reach the conclusion that, from the structure of the field equations, the behaviour of Λ and G are related, but taking into account the observational data, we conclude that the Λ behaves as a positive decreasing time function while G is growing but in the long time regimen it tends to a constant value. In the scalar models, our solutions predict a “positive” dynamical cosmological constant in all the obtained solutions while the behaviour of G yields indeterminate, since its depends on a free parameter, G≈t 2α , so it may be growing or decreasing as in the scalar-tensor theories. 相似文献
17.
We have studied anisotropic and homogeneous Locally Rotationally Symmetric (LRS) Bianchi type-I, Bianchi type-V, Bianchi type-III, Bianchi type-VI0, and Kantowaski–Sachs space-times with variable equation of state (EoS) parameter (w) in General Relativity. A special form of deceleration parameter (q) which gives an early deceleration and late time accelerating cosmological model has been utilized to solve the field equations. The geometrical and physical aspects of the models are also studied. 相似文献
18.
D. Lorenz 《Astrophysics and Space Science》1982,85(1-2):63-67
The Einstein-Maxwell equations are integrated for a tilted Bianchi type VIo space-time with stiff matter and an electromagnetic field. The solution represents an anisotropic homogeneous cosmological model which tends to isotropic expansion. 相似文献
19.
Spatially-homogeneous and anisotropic Bianchi type-III, V, VI0 cosmological models in Rosen's (1973) bimetric theory of gravitation are considered. It is shown that, in each case, when
the soure of the gravitation field is a perfect fluid distribution Bianchi type cosmological models do not exist. Hence vacuum
models are presented and studied.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
The Bianchi type V and VI0 models have been investigated in Lyra geometry in both the cases with the gauge function is a time dependent and =constant. The physical behaviour of these models has been discussed. 相似文献