Bimetric Theory Of Gravitation Research Articles

BIANCHI TYPE I MAGNETIZED DARK ENERGY COSMOLOGICAL MODEL IN BIMETRIC THEORY OF GRAVITATION

We investigatedBianchitype-I magnetized dark energy cosmological model in bimetric theory of gravitation. The paper explores the geometrical and physical properties of the model inboth power law andexponential law. All the physical parameters of both the lawsare decreasing with time. It is found thatexpansion with steady speed in power law model while in exponential model, our universe has accelerating contraction. Other geometrical and physical properties are also discussed.

BULK VISCOUS BIANCHI TYPE I BAROTROPIC FLUID COSMOLOGICAL MODEL WITH VARYING Λ AND FUNCTIONAL RELATION ON HUBBLE PARAMETER IN ROSEN’S BIMETRIC GRAVITY

We have deduced that bulk viscous Bianchi type I barotropic fluid cosmological model with varying $\Lambda$ and functional relation on hubble parameter by solving the field equations bimetric theory of gravitation. It is observed that our model has exponentially accelerating expansion at late time starting with decelerating expansion which agreed the observation of Perlmutter (1998), Knop (2003), Tegmark (2004) and Spergel (2006). In the beginning, our model has more than three spatial-dimensions then it switched over to three-dimensional spatial geometry at late epoch of time and it is agreed with Borkar et al. (2013). Other geometrical and physical behavior of the model have been studied.

CPTM Discrete Symmetry, Quantum Wormholes and Cosmological Constant Problem

We discuss the consequences of the charge, parity, time, and mass (CPTM) extended reversal symmetry for the problems of the vacuum energy density and value of the cosmological constant. The results obtained are based on the framework with the separation of extended space-time of the interest on the different regions connected by this symmetry with the action of the theory valid for the full space-time and symmetrical with respect to the extended CPTM transformations. The cosmological constant is arising in the model due the gravitational interactions between the different parts of the space-time trough the quantum non-local vertices. It is proposed that the constant’s value depends on the form and geometry of the vertices that glue the separated parts of the extended solution of Einstein equations determining, in turn, its classical geometry. The similarity of the proposed model to the bimetric theories of gravitation is also discussed.

Strength of singularities in varying constants theories

In this paper we consider a specific type of the bimetric theory of gravitation with the two different metrics introduced in the cosmological frame. Both metrics respect all the symmetries of the standard FLRW solution and contain conformally related spatial parts. One of the metric is assumed to describe the causal structure for the matter. Another metric defines the causal structure for the gravitational interactions. A crucial point is that the spatial part of the metric describing gravity is given by the spatial part of the matter metric conformally rescaled by a time-dependent factor alpha which, as it turns out, can be linked to the effective gravitational constant and the effective speed of light. In the context of such a bimetric framework we examine the strength of some singular cosmological scenarios in the sense of the criteria introduced by Tipler and Królak. In particular, we show that for the nonsingular scale factor associated with the matter metric, both the vanishing or blowing up of the factor alpha for some particular moment of the cosmic expansion may lead to a strong singularity with infinite value of the energy density and infinite value of the pressure.

Spherically Symmetric Static Charged Anisotropic Fluid in Rosen's Bimetric Theory of Gravitation

ABSTRACTIn this paper we have obtained an exact solution for the static spherically symmetric space-time with charged anisotropic fluid distribution in context of Rosen's Bimetric General Relativity (BGR).

Models of Compact Stars in the Bimetric Scalar-Tensor Theory of Gravitation

We investigate static spherically-symmetric configurations of gravitating masses in the bimetric scalar-tensor theory of gravitation. In the gravitational sector, the theory contains the metric tensor, a scalar field and a background metric as an absolute variable of the theory. The analysis is presented for the simplest version of the theory with a constant coupling function and a zero cosmological function. We show that, depending on the value of the theory parameter, the masses for superdense compact configurations can be essentially larger compared to the configurations in general relativity.

FLRW solution in bimetric theory of gravitation

We have derived FLRW line-element in Bimetric Theory of Gravitation (BTG) by solving Rosen’s field equations, and it is concluded that the geometry of our model in BTG is agreed with the geometry of FLRW model in GR. It is also realized that for the large value of t, the deceleration parameter q in our model admits the value which is close to the value at present epoch predicted by the observations of [44-48].This This shows that our FLRW model in BTG is found to be in an accelerating phase at present epoch which is not the case in GR. Other geometrical and physical aspects to the model are also studied.

Plane Symmetric Anisotropic Dark Energy Cosmological Model in the Bimetric Theory of Gravitation

The plane symmetric space-times with anisotropic dark energy and with constant deceleration parameter have been derived by solving the Rosen's field equations in the Bimetric theory of gravitation. We explored both models in power law as well as in exponential law. In power law, the model attains both phases accelerating as well as decelerating in the expansion with anisotropic fluid, which is in the form of dark energy, and there is no chance of real matter in this power law. In exponential law, the model is dust, isotropized in nature with constant acceleration in the expansion. Further, other geometrical and physical aspects of the models are also studied.

LRS Bianchi type I magnetized cosmological model with perfect fluid and with quintessence, Chaplygin gas dark energy in bimetric theory of gravitation

We studied the LRS Bianchi type I cosmological models with perfect fluid, quintessence and standard Chaplygin gas dark energy in the presence as well as in the absence of magnetic field [Formula: see text], in bimetric theory of gravitation. It is realized that the magnetic field controlled the whole behavior of the models. In the absence of magnetic field, these models exists and the model never exists in the presence of magnetic field. The geometry of quintessence model for [Formula: see text] and standard Chaplygin gas model coincide and their physical behavior are same in the absence of magnetic field. Some geometrical and physical properties of each of the model are explored. The model have also been studied in regard with the singularities and it is pointed out that the model is singular in the presence of magnetic field and nonsingular in the absence of magnetic field.

Evaluation of Bianchi type VI0 magnetized anisotropic dark energy models with constant deceleration parameter in bimetric theory of gravitation

In this paper, Bianchi type VI0 magnetized anisotropic dark energy models with constant deceleration parameter have been studied by solving the Rosen's field equations in Bimetric theory of gravitation. The models corresponding to power law expansion and exponential law expansion have been evaluated and studied their nature geometrically and physically. It is seen that there is real visible matter (baryonic matter) suddenly appeared only for small interval of time 0.7 ≤ t < 0.7598 and for the remaining whole range of time t, there is dark energy matter in the universe. Our investigations are supported to the observational fact that the usual matter described by known particle theory is about 4% and the dark energy cause the accelerating expansion of the universe and several high precision observational experiments, especially the Wilkinson Microwave Anisotropic Probe (WMAP) satellite experiment (see [C. L. Bennett et al., Astrophys. J. Suppl. Ser. 148 (2003) 1; WMAP Collab. (D. N. Spergel et al.), Astrophys. J. Suppl. Ser. 148 (2003) 175; D. N. Spergel et al., Astrophys. J. Suppl. 170 (2007) 377; WMAP Collab. (E. Komastu et al.), Astrophys. J. Suppl. 180 (2009) 330; WMAP Collab. (G. Hinshaw et al.), Astrophys. J. Suppl. 208 (2013) 19; Plank Collab. (P. A. R. Ade), arXiv:1303.5076; arXiv:1303.5082]) conclude that the dark energy occupies near about 73% of the energy of the universe and dark matter is about 23%. In exponential law of expansion, our model is fully occupied by real visible matter and there is no chance of dark energy and dark matter.

On Kantowski-Sachs Viscous Fluid Model in Bimetric Relativity

Kantowski-Sachs plane symmetric models are investigated in bimetric theory of gravitation proposed by Rosen [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310035003100330038003900340034000000 in the context of bulk viscous fluid. Taking conservation law and the equation of state, two different models of the universe are obtained. It is observed that Kantowski-Sachs vacuum model obtained in first case and bulk viscous fluid model obtained in second case. It is also observed that the bulk viscous cosmological model always represents an accelerated universe and consistent with the recent observations of type-1a supernovae. Some physical and geometrical features of the viscous fluid model are studied.

Non-static plane symmetric massive string magnetized perfect fluid cosmological models in bimetric theory of gravitation

In this paper,we investigate the non-static massive string magnetized barotropic perfect fluid cosmological models in Rosen's (Gen.Rel.Grav.Vol.4 (1973) 435) bimetric theory of gravitation. Using the relation isotropic pressure 'p' directly proportional to energy density 'ρ' ( i.e p = Є1 ρ , where -1 ≤ Є1 ≤ 1) , dust filled geometric string model and stiff fluid filled model of the universe are obtained. Some physical and geometrical behavior of the exhibited models are also discussed.

The Measurement of and in Bianchi Type-I Anisotropic Dark Energy Cosmological Model with Constant Deceleration Parameter in Bimetric Theory of Gravitation

The Measurement of and in Bianchi Type-I Anisotropic Dark Energy Cosmological Model with Constant Deceleration Parameter in Bimetric Theory of Gravitation

LRS Bianchi Type I Cosmological Models with Perfect Fluid and Dark Energy in Bimetric Theory of Gravitation

LRS Bianchi Type I Cosmological Models with Perfect Fluid and Dark Energy in Bimetric Theory of Gravitation

Inhomogeneous Cosmological Models in Bimetric Theory of Gravitation

Plane symmetric inhomogeneous cosmological models for perfect fluid distribution are investigated in the frame work of Rosen's bimetric theory of gravitation. A negative pressure corresponding to false vacuum state is considered. Some of the physical and kinematical properties of the models are discussed.

Axially Symmetric Cosmological Model with Wet Dark Fluid in Bimetric Theory of Gravitation

The purpose of this paper is to investigate the role of wet dark fluid in axially symmetric cosmological model within the frame work of bimetric theory of gravitation proposed by Rosen (Gen. Relativ. Gravit. 4:435, 1973). In this theory, it is observed that there is no contribution from wet dark fluid.

Bianchi Type-I Massive String Magnetized Barotropic Perfect Fluid Cosmological Model in the Bimetric Theory of Gravitation

We investigate the Bianchi type-I massive string magnetized barotropic perfect fluid cosmological model in Rosen's bimetric theory of gravitation with and without a magnetic field by applying the techniques used by Latelier (1979, 1980) and Stachel (1983). To obtain a deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution. The physical and geometrical significance of the model are discussed. By comparing our model with the model of Bali et al. (2007), it is realized that there are no big-bang and big-crunch singularities in our model and T = 0 is not the time of the big bang, whereas the model of Bali et al. starts with a big bang at T = 0. Further, our model is in agreement with Bali et al. (2007) as time increases in the presence, as well as in the absence, of a magnetic field.

Bianchi type-I massive string magnetized barotropic perfect fluid cosmological model in bimetric theory

Bianchi type-I massive string cosmological model for perfect fluid distribution in the presence of magnetic field is investigated in Rosen’s [Gen. Relativ. Gravit. 4, 435 (1973)] bimetric theory of gravitation. To obtain the deterministic model in terms of cosmic time, we have used the condition A = (BC) n , where n is a constant, between the metric potentials. The magnetic field is due to the electric current produced along the x-axis with infinite electrical conductivity. Some physical and geometrical properties of the exhibited model are discussed and studied.

Charged fluid sphere in bimetric general theory of relativity

Static and spherical symmetric solutions of the field equations in the bimetric general theory of gravitation are obtained for perfect and anisotropic charged fluids under the assumption that the physical metric admits a one-parameter group of conformal motion. All solutions are matched to the Reissner–Nordstrom metric and possess positive energy density larger than the stresses, everywhere within the sphere. The solution agrees with Einstein’s general relativity for a physical system comparable to the size of the universe, such as the solar system.

Inhomogeneous Plane Symmetric String Cosmological Models in Bimetric Theory

It is shown that the inhomogeneous plane symmetric perfect fluid distribution and cosmic strings do not survive in frame work of bimetric theory of gravitation proposed by Rosen (Gen. Relativ. Gravit. 4:435, 1973). Hence vacuum models are presented and studied.