286 research outputs found
Hawking radiation as tunneling from squashed Kaluza-Klein black hole
We discuss Hawking radiation from a five-dimensional squashed Kaluza-Klein
black hole on the basis of the tunneling mechanism. A simple manner, which was
recently suggested by Umetsu, is possible to extend the original derivation by
Parikh and Wilczek to various black holes. That is, we use the two-dimensional
effective metric, which is obtained by the dimensional reduction near the
horizon, as the background metric. By using same manner, we derive both the
desired result of the Hawking temperature and the effect of the back reaction
associated with the radiation in the squashed Kaluza-Klein black hole
background.Comment: 16 page
Energy and Momentum Distributions of a (2+1)-dimensional black hole background
Using Einstein, Landau-Lifshitz, Papapetrou and Weinberg energy-momentum
complexes we explicitly evaluate the energy and momentum distributions
associated with a non-static and circularly symmetric three-dimensional
spacetime. The gravitational background under study is an exact solution of the
Einstein's equations in the presence of a cosmological constant and a null
fluid. It can be regarded as the three-dimensional analogue of the Vaidya
metric and represents a non-static spinless (2+1)-dimensional black hole with
an outflux of null radiation. All four above-mentioned prescriptions give
exactly the same energy and momentum distributions for the specific black hole
background. Therefore, the results obtained here provide evidence in support of
the claim that for a given gravitational background, different energy-momentum
complexes can give identical results in three dimensions. Furthermore, in the
limit of zero cosmological constant the results presented here reproduce the
results obtained by Virbhadra who utilized the Landau-Lifshitz energy-momentum
complex for the same (2+1)-dimensional black hole background in the absence of
a cosmological constant.Comment: 19 pages, LaTeX, v3: references added, to appear in Int.J.Mod.Phys.
Thermal radiation of various gravitational backgrounds
We present a simple and general procedure for calculating the thermal
radiation coming from any stationary metric. The physical picture is that the
radiation arises as the quasi--classical tunneling of particles through a
gravitational barrier. We show that our procedure can reproduce the results of
Hawking and Unruh radiation. We also show that under certain kinds of
coordinate transformations the temperature of the thermal radiation will change
in the case of the Schwarzschild black holes. In addition we apply our
procedure to a rotating/orbiting system and show that in this case there is no
radiation, which has experimental implications for the polarization of
particles in circular accelerators.Comment: 6 pages revtex, added references, publication version. To be
published IJMP
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
Hawking Radiation of Black Rings from Anomalies
We derive Hawking radiation of 5-dimensional black rings from gauge and
gravitational anomalies using the method proposed by Robinson and Wilczek. We
find as in the black hole case, the problem could reduce to a (1+1) dimensional
field theory and the anomalies result in correct Hawking temperature for
neutral,dipole and charged black rings.Comment: 15 pages,Latex; revised version, typos corrected, reference added
Quasinormal Modes in Noncommutative Schwarzschild black holes
We investigate the quasinormal modes of a massless scalar field in a
Schwarzschild black hole, which is deformed due to noncommutative corrections.
We present the deformed Schwarzschild black hole solution, which depends on the
noncommutative parameter , and we extract the master equation as a
Schr\"odinger-like equation, giving the explicit expression of the effective
potential which is modified due to the noncommutative corrections. We solve the
master equation numerically and we find that the noncommutative gravitational
corrections ``break" the stability of the scalar perturbations in the long time
evolution of the massless scalar field. The significance of these results is
twofold. Firstly, our results can be related to the detection of gravitational
waves by the near future gravitational wave detectors, such as LISA, which will
have a significantly increased accuracy. In particular, these observed
gravitational waves produced by binary strong gravitational systems have
oscillating modes which can provide valuable information. Secondly, our results
can serve as an additional tool to test the predictions of general relativity,
as well as to examine the possible detection of this kind of gravitational
corrections.Comment: 16 pages, 12 figure
Gravitational Anomaly and Hawking Radiation of Brane World Black Holes
We apply Wilczek and his collaborators' anomaly cancellation approach to the
3-dimensional Schwarzschild- and BTZ-like brane world black holes induced by
the generalized C metrics in the Randall-Sundrum scenario. Based on the fact
that the horizon of brane world black hole will extend into the bulk spacetime,
we do the calculation from the bulk generalized C metrics side and show that
this approach also reproduces the correct Hawking radiation for these brane
world black holes. Besides, since this approach does not involve the dynamical
equation, it also shows that the Hawking radiation is only a kinematic effect.Comment: 11 pages. v2: minor changes and references adde
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