30 research outputs found
Effect of NUT parameter on the analytic extension of the Cauchy horizon that develop in colliding wave spacetimes
The Cauchy horizon forming colliding wave solution due to Chandrasekhar and
Xanthopoulos (CX) has been generalized by inclusion of the NUT (Newman - Unti -
Tamburino) parameter. This is done by transforming the part of the inner
horizon region of a Kerr-Newman-NUT black hole into the space of colliding
waves. By taking appropriate combination of Killing vectors and analytically
extending beyond the Cauchy horizon the time-like hyperbolic sigularities are
resolved as well. This provides another example of its kind among the type - D
metrics with special emphasis on the role of the NUT parameter. Finally, it is
shown that horizons of colliding higher dimensional plane waves obtained from
the black p-branes undergoes a similar procedure of analytic extension.Comment: 26 pages. 3 ps figure
General Relativistic Fall on a Thick-Plate
As an extension of a thin-shell, we adopt a single parametric plane-symmetric
Kasner-type spacetime to represent an exact thick-plate. This naturally extends
the domain wall spacetime to a domain thick-wall case. Physical properties of
such a plate with symmetry axis and thickness are
investigated. Geodesic analysis determines the possibility of a Newtonian-like
fall, namely with constant negative acceleration as it is near the Earth's
surface. This restricts the Kasner-like exponents to a finely-tuned set, which
together with the thickness and energy parameter determine the G-force of the
plate. In contrast to the inverse square law, the escape velocity of the
thick-shell is unbounded. The metric is regular everywhere but expectedly the
energy-momentum of the thick-plate remains problematic.Comment: 11 pages, 1 figur
Colliding Wave Solutions in a Symmetric Non-metric Theory
A method is given to generate the non-linear interaction (collision) of
linearly polarized gravity coupled torsion waves in a non-metric theory.
Explicit examples are given in which strong mutual focussing of gravitational
waves containing impulsive and shock components coupled with torsion waves does
not result in a curvature singularity. However, the collision of purely torsion
waves displays a curvature singularity in the region of interaction.Comment: 16 pages, 1 ps figure, It will appear in Int. Jour. of Theor. Physic
Formation of Wormholes by Dark Matter in the Galaxy Dragonfly 44
Recently, ultra diffuse galaxy (UDG) of Dragonfly 44 in the Coma Cluster was
observed and observations of the rotational speed suggest that its mass is
almost same as the mass of the Milky Way. On the other hand, interestingly, the
galaxy emits only 1 \% of the light emitted by the Milky Way. Then, astronomers
reported that Dragonfly 44 may be made almost entirely of dark matter. In this
study we try to show that the dark matter that constitutes Dragonfly 44 can
form the wormhole or not. Two possible dark matter profiles are used, namely,
ultra diffuse galaxy King's model and generalized Navarro-Frenk-White (NFW)
dark matter profile. We have shown that King's model dark matter profile does
not manage to provide wormhole whereas generalized Navarro-Frenk-White (NFW)
dark matter profile is managed to find wormholes.Comment: 8 pages, two columns. Accepted for publication in Canadian Journal of
Physic
Probing naked singularities in the charged and uncharged -metrics with quantum wave packets
The non-trivial naked singularities that possess directional behavior in the
charged and uncharged Zipoy-Voorhees (ZV) spacetimes, known as {\gamma} -
metrics are investigated within the context of quantum mechanics. Classically
singular spacetime is understood as a geodesic incompleteness with respect to a
particle probe, while quantum singularity is understood as a non-unique
evolution of test quantum wave packets. In this study, quantum wave packets
obeying Klein - Gordon equation are used to probe timelike naked singularities.
It is shown by rigorous mathematical calculations that the outermost
singularity developed in the charged and uncharged Zipoy-Voorhees spacetime on
the equatorial plane is quantum mechanically singular for all values of the
deformation parameter {\gamma}. However, directional singularities that develop
on the symmetry axis is shown to be healed partially for specific range of the
parameter {\gamma}, if the analysis is restricted purposely to only specific
mode (s-wave mode). Allowing arbitrary modes, classical directional
singularities remains quantum singular.Comment: Slightly detailed versio
Stationary, charged Zipoy-Voorhees metric from colliding wave spacetime
Through the Ernst formalism we provide expression for a class of colliding
Einstein-Maxwell (EM) metrics with cross polarization. Local isometry is
imposed as a means to transform interaction region of the spacetime into
stationary, charged Zipoy-Voorhees (ZV) metric in Schwarzschild coordinates.
The ZV-metric is known to describe planetary/stellar objects with arbitrary
topology. "The world may be seen in a grain of sand" - William Blake