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F. Rahaman

Publications and source records attributed to F. Rahaman.

At least 55 records · Page 3Linked to original sources
arXiv2008

Semiclassical gravitational effects around global monopole in Brans-Dicke theory

In recent past, W.A.Hiscock [ Class.Quan.Grav. (1990) 7,6235 ] studied the semi classical gravitational effects around global monopole. He obtained the vacuum expectation value of the stress-energy tensor of an arbitrary collection of conformal mass less free quantum fields (scalar, spinor and vectors) in the space time of a global monopole. With this stress-energy tensor, we study the semi classical gravitational effects of a global monopole in the context of Brans-Dicke theory of gravity.

gr-qc↗
arXiv2007

Static global monopoles in higher dimensional space time

We present an exact solution around global monopole resulting from the breaking of a global S0(3) symmetry in a five dimensional space time. We have shown that the global monopole in higher dimensional space time exerts gravitational force which is attractive in nature. It is also shown that the space around global monopole has a deficit solid angle. Finally, we study monopole in higher dimensional space time within the framework of Lyra geometry.

gr-qc↗
arXiv2007

Some new class of Chaplygin Wormholes

Some new class of Chaplygin wormholes are investigated in the framework of a Chaplygin gas with equation of state $ p = - \frac{A}ρ$, $A>0$. Since empty spacetime ($ p = ρ= 0 $) does not follow Chaplygin gas, so the interior Chaplygin wormhole solutions will never asymptotically flat. For this reason, we have to match our interior wormhole solution with an exterior vacuum solution i.e. Schwarzschild solution at some junction interface, say $ r = a $. We also discuss the total amount of matter characterized by Chaplygin gas that supplies fuel to construct a wormhole.

gr-qc↗
arXiv2007

Wormhole and C-field: Revisited

Recently, Rahaman et al [ Nuovo.Cim 119B, 1115(2004)] have shown that the static spherically symmetric solutions in presence of C-field give rise to wormhole geometry. We highlight some of the characteristics of this wormhole, which have not been considered in the previous study.

gr-qc↗
arXiv2007

Do Solar system tests permit higher dimensional general relativity?

We perform a survey whether higher dimensional Schwarzschild space-time is compatible with some of the solar system phenomena. As a test we examine five well known solar system effects, viz., (1) Perihelion shift, (2) Bending of light, (3) Gravitational redshift, (4) Gravitational time delay and (5) Motion of test particle in the framework of general relativity with higher dimensions. It is shown that the results related to all these physical phenomena are mostly incompatible with the higher dimensional version of general relativity except that of Motion of test particle. We compare all these results with the available data in the literature.

gr-qc↗
arXiv2007

Particle Motion Around Tachyon Monopole

Recently, Li and Liu have studied global monoole of tachyon in a four dimensional static space-time. We analyze the motion of massless and massive particles around tachyon monopole. Interestingly, for the bending of light rays due to tachyon monopole instead of getting angle of deficit we find angle of surplus. Also we find that the tachyon monopole exerts an attractive gravitational force towards matter.

gr-qc↗
arXiv2007

Gravitational lensing by stable C-field wormhole

It has been recently shown that Hoyle-Narlikar's C-field theory admits wormhole geometry. We derive the deflection angle of light rays caused by C-field wormhole in the strong field limit approach of gravitational lensing theory. The linearized stability of C-field wormhole under spherically symmetric perturbations about static equilibrium is also explored.

gr-qc↗
arXiv2007

Non static Global monopole in Lyra geometry

A class of non static solutions around a global monopole resulting from the breaking of a global S0(3) symmetry based on Lyra geometry are obtained. The solutions are obtained using the functional separability of the metric coefficients. We have shown that the monopole exerts attractive gravitational effects on test particles.

gr-qc↗
arXiv2007

A study of global monopole in Lyra geometry

A class of exact static solution around a global monopole resulting from the breaking of a global S0(3) symmetry is obtained in the context of Lyra geometry. Our solution is shown to possess an interesting feature like wormholes space-time. It has been shown that the global monopole exerts no gravitational force on surrounding non-relativistic matter.

gr-qc↗
arXiv2007

A Theoretical Construction of Thin Shell Wormhole from Tidal Charged Black hole

Recently, Dadhich et al [ Phys.Lett.B 487, 1 (2000)] have discovered a black hole solution localized on a three brane in five dimensional gravity in the Randall-Sundrum scenario. In this article, we develop a new class of thin shell wormhole by surgically grafting above two black hole spacetimes. Various aspects of this thin wormhole are also analyzed.

gr-qc↗
arXiv2007

Thin Domain Walls in Lyra Geometry

This paper studies thin domain walls within the frame work of Lyra Geometry. We have considered two models. First one is the thin domain wall with negligible pressures perpendicular and transverse direction to the wall and secondly, we take a particular type of thin domain wall where the pressure in the perpendicular direction is negligible but transverse pressures are existed. It is shown that the thin domain walls have no particle horizon and the gravitational force due to them is attractive.

gr-qc↗
arXiv2007

Vacuum less global monopole in Brans-Dicke theory

In the present work, the gravitational field of a vacuum less global monopole has been investigated in Brans-Dicke theory under weak field assumption of the field equations. It has been shown that the vacuum less global monopole exerts attractive gravitational effects on a test particle. It is dissimilar to the case studied in general relativity.

gr-qc↗
arXiv2006

Does phantom energy produce black hole?

We have found an exact solution of spherically symmetrical Einstein equations describing a black hole with a special type phantom energy source. It is surprising to note that our solution is analogous to Reissner-Nordström black hole.

gr-qc↗
arXiv2006

Bianchi -I Cosmology with Magnetic Field in Lyra Geometry

A new class of Bianchi - I cosmological model with magnetic field within the frame work of Lyra geometry has been presented . Exact solutions to the field equations for the model are obtained . The physical and kinematical behaviors of the model have been discussed.

gr-qc↗