44 research outputs found
On the energy of charged black holes in generalized dilaton-axion gravity
In this paper we calculate the energy distribution of some charged black
holes in generalized dilaton-axion gravity. The solutions correspond to charged
black holes arising in a Kalb-Ramond-dilaton background and some existing
non-rotating black hole solutions are recovered in special cases. We focus our
study to asymptotically flat and asymptotically non-flat types of solutions and
resort for this purpose to the M{\o}ller prescription. Various aspects of
energy are also analyzed.Comment: LaTe
Teleparallel Energy-Momentum Distribution of Spatially Homogeneous Rotating Spacetimes
The energy-momentum distribution of spatially homogeneous rotating spacetimes
in the context of teleparallel theory of gravity is investigated. For this
purpose, we use the teleparallel version of Moller prescription. It is found
that the components of energy-momentum density are finite and well-defined but
are different from General Relativity. However, the energy-momentum density
components become the same in both theories under certain assumptions. We also
analyse these quantities for some special solutions of the spatially
homogeneous rotating spacetimes.Comment: 12 pages, accepted for publication in Int. J. Theor. Phy
Energy Distribution for Non-commutative Radiating Schwarzschild Black Holes
The aim of this article is the calculation of the energy-momentum for a
non-commutative radiating Schwarzschild black hole in order to obtain the
expressions for energy. We make the calculations with the Einstein and M\oller
prescriptions. We show that the expressions for energy in both the
prescriptions depend on the mass , parameter and radial coordinate.
We make some comparisons between the results. Our results show that the
Einstein prescription is a more powerful concept than the M\oller prescription.Comment: 5 pages and 6 figures. Revised version submitted in Int.J.Theor.Phys.
after minor revisio
The Energy of Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics
According to the Einstein, Weinberg, and M{\o}ller energy-momentum complexes,
we evaluate the energy distribution of the singularity-free solution of the
Einstein field equations coupled to a suitable nonlinear electrodynamics
suggested by Ay\'{o}n-Beato and Garc\'{i}a. The results show that the energy
associated with the definitions of Einstein and Weinberg are the same, but
M{\o}ller not. Using the power series expansion, we find out that the first two
terms in the expression are the same as the energy distributions of the
Reissner-Nordstr\"{o}m solution, and the third term could be used to survey the
factualness between numerous solutions of the Einstein field eqautions coupled
to a nonlinear electrodynamics.Comment: 11 page
Energy Distribution in f(R) Gravity
The well-known energy problem is discussed in f(R) theory of gravity. We use
the generalized Landau-Lifshitz energy-momentum complex in the framework of
metric f(R) gravity to evaluate the energy density of plane symmetric solutions
for some general f(R) models. In particular, this quantity is found for some
popular choices of f(R) models. The constant scalar curvature condition and the
stability condition for these models are also discussed. Further, we
investigate the energy distribution of cosmic string spacetime.Comment: 15 pages, accepted for publication in Gen. Relativ. & Gra
Energy-Momentum Localization for a Space-Time Geometry Exterior to a Black Hole in the Brane World
In general relativity one of the most fundamental issues consists in defining
a generally acceptable definition for the energy-momentum density. As a
consequence, many coordinate-dependent definitions have been presented, whereby
some of them utilize appropriate energy-momentum complexes. We investigate the
energy-momentum distribution for a metric exterior to a spherically symmetric
black hole in the brane world by applying the Landau-Lifshitz and Weinberg
prescriptions. In both the aforesaid prescriptions, the energy thus obtained
depends on the radial coordinate, the mass of the black hole and a parameter
, while all the momenta are found to be zero. It is shown that for
a special value of the parameter , the Schwarzschild space-time
geometry is recovered. Some particular and limiting cases are also discussed.Comment: 10 pages, sections 1 and 3 slightly modified, references modified and
adde
Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-time Geometry
An analysis of the energy-momentum localization for a four-dimensional\break
Schwarzschild black hole surrounded by quintessence is presented in order to
provide expressions for the distributions of energy and momentum. The
calculations are performed by using the Landau-Lifshitz and Weinberg
energy-momentum complexes. It is shown that all the momenta vanish, while the
expression for the energy depends on the mass of the black hole, the state
parameter and the normalization factor . The special case of
is also studied, and two limiting cases are examined.Comment: 9 page
Energy Contents of Some Well-Known Solutions in Teleparallel Gravity
In the context of teleparallel equivalent to General Relativity, we study
energy and its relevant quantities for some well-known black hole solutions.
For this purpose, we use the Hamiltonian approach which gives reasonable and
interesting results. We find that our results of energy exactly coincide with
several prescriptions in General Relativity. This supports the claim that
different energy-momentum prescriptions can give identical results for a given
spacetime. We also evaluate energy-momentum flux of these solutions.Comment: 16 pages, accepted for publication in Astrophys. Space Sc
Charged Dilaton, Energy, Momentum and Angular-Momentum in Teleparallel Theory Equivalent to General Relativity
We apply the energy-momentum tensor to calculate energy, momentum and
angular-momentum of two different tetrad fields. This tensor is coordinate
independent of the gravitational field established in the Hamiltonian structure
of the teleparallel equivalent of general relativity (TEGR). The spacetime of
these tetrad fields is the charged dilaton. Our results show that the energy
associated with one of these tetrad fields is consistent, while the other one
does not show this consistency. Therefore, we use the regularized expression of
the gravitational energy-momentum tensor of the TEGR. We investigate the energy
within the external event horizon using the definition of the gravitational
energy-momentum.Comment: 22 Pages Late
Cosmic acceleration and phantom crossing in -gravity
In this paper, we propose two new models in gravity to realize
universe acceleration and phantom crossing due to dark torsion in the
formalism. The model parameters are constrained and the observational test are
discussed. The best fit results favors an accelerating universe with possible
phantom crossing in the near past or future followed respectively by matter and
radiation dominated era.Comment: 20 pages, 18 figures, Will appear in Astrophys Space Sc