The Energy Distribution in a Static Spherically Symmetric Nonsingular Black Hole Space-Time

We calculate the energy distribution in a static spherically symmetric nonsingular black hole space-time by using the Tolman's energy-momentum complex. All the calculations are performed in quasi-Cartesian coordinates. The energy distribution is positive everywhere and be equal to zero at origin. We get the same result as obtained by Y-Ching Yang by using the Einstein's and Weinberg's prescriptions.Comment: 5 pages, no figure

Energy Distribution of a Charged Regular Black Hole

We calculate the energy distribution of a charged regular black hole by using the energy-momentum complexes of Einstein and M{\o}ller.Comment: 6 pages, no figure

Energy and momentum of cylindrical gravitational waves. II

Recently Nathan Rosen and the present author obtained the energy and momentum densities of cylindrical gravitational waves in Einstein's prescription and found them to be finite and reasonable. In the present paper we calculate the same in prescriptions of Tolman as well as Landau and Lifshitz and discuss the results.Comment: 8 pages, LaTex, To appear in Pramana- J. Physic

Energy Associated with Schwarzschild Black Hole in a Magnetic Universe

In this paper we obtain the energy distribution associated with the Ernst space-time (geometry describing Schwarzschild black hole in Melvin's magnetic universe) in Einstein's prescription. The first term is the rest-mass energy of the Schwarzschild black hole, the second term is the classical value for the energy of the uniform magnetic field and the remaining terms in the expression are due to the general relativistic effect. The presence of the magnetic field is found to increase the energy of the system.Comment: RevTex, 8 pages, no figures, a few points are clarified, to appear in Int. J. Mod. Phys. A. This paper is dedicated to Professor G. F. R. Ellis on the occasion of his 60th birthda

Bergmann-Thomson energy-momentum complex for solutions more general than the Kerr-Schild class

In a very well-known paper, Virbhadra's research group proved that the Weinberg, Papapetrou, Landau and Lifshitz, and Einstein energy-momentum complexes ``coincide'' for all metrics of Kerr-Schild class. A few years later, Virbhadra clarified that this ``coincidence'' in fact holds for metrics more general than the Kerr-Schild class. In the present paper, this study is extended for the Bergmann-Thomson complex and it is proved that this complex also ``coincides'' with those complexes for a more general than the Kerr-Schild class metric.Comment: RevTex, 12 page

Energy associated with charged dilaton black holes

It is known that certain properties of charged dilaton black holes depend on a free parameter $\beta$ which controls the strength of the coupling of the dilaton to the Maxwell field. We obtain the energy associated with static spherically symmetric charged dilaton black holes for arbitrary value of the coupling parameter and find that the energy distribution depends on the value of $\beta$. With increasing radial distance, the energy in a sphere increases for $\beta = 0$ as well as for $\beta 1$, and remains constant for $\beta = 1$. However, the total energy turns out to be the same for all values of $\beta$.Comment: singlespaced 7 pages, LaTex, no figures, misprints corrected, to appear in Int. J. Mod. Phys.

Janis-Newman-Winicour and Wyman solutions are the same

We show that the well-known most general static and spherically symmetric exact solution to the Einstein-massless scalar equations given by Wyman is the same as one found by Janis, Newman and Winicour several years ago. We obtain the energy associated with this spacetime and find that the total energy for the case of the purely scalar field is zero.Comment: 9 pages, LaTex, no figures, misprints corrected, to appear in Int. J. Mod. Phys.

Strong gravitational lensing by a rotating non-Kerr compact object

We study the strong gravitational lensing in the background of a rotating non-Kerr compact object with a deformed parameter $\epsilon$ and an unbound rotation parameter $a$. We find that the photon sphere radius and the deflection angle depend sharply on the parameters $\epsilon$ and $a$. For the case in which the black hole is more prolate than a Kerr black hole, the photon sphere exists only in the regime $\epsilon\leq\epsilon_{max}$ for prograde photon. The upper limit $\epsilon_{max}$ is a function of the rotation parameter $a$. As $\epsilon>\epsilon_{max}$, the deflection angle of the light ray closing very to the naked singularity is a positive finite value, which is different from those in both the usual Kerr black hole spacetime and in the rotating naked singularity described by Janis-Newman-Winicour metric. For the oblate black hole and the retrograde photon, there does not exist such a threshold value. Modelling the supermassive central object of the Galaxy as a rotating non-Kerr compact object, we estimated the numerical values of the coefficients and observables for gravitational lensing in the strong field limit.Comment: 16 pages, 10 figures. The corrected version to be appeared in Phys. Rev.

M{\o}ller Energy for the Kerr-Newman metric

The energy distribution in the Kerr-Newman space-time is computed using the M{\o}ller energy-momentum complex. This agrees with the Komar mass for this space-time obtained by Cohen and de Felice. These results support the Cooperstock hypothesis.Comment: 8 pages, 1 eps figure, RevTex, accepted for publication in Mod. Phys. Lett.