224 research outputs found
Self-Gravitational Corrections to the Cardy-Verlinde Formula and the FRW Brane Cosmology in SdS_5 Bulk
The semiclassical corrections to the Cardy-Verlinde entropy of a
five-dimensional Schwarzschild de-Sitter black hole (SdS_5) are explicitly
evaluated. These corrections are considered within the context of KKW analysis
and arise as a result of the self-gravitation effect. In addition, a
four-dimensional spacelike brane is considered as the boundary of the SdS_5
bulk background. It is already known that the induced geometry of the brane is
exactly given by that of a radiation-dominated FRW universe. By exploiting the
CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the
first Friedmann-like equation which is the equation of the brane motion. The
additional term that arises due to the semiclassical analysis can be viewed as
stiff matter where the self-gravitational corrections act as the source for it.
This result is contrary to standard analysis that regards the charge of SdS_5
bulk black hole as the source for stiff matter. Furthermore, we rewrite the
Friedmann-like equation in a such way that it represents the conservation
equation of energy of a point particle moving in a one-dimensional effective
potential. The self-gravitational corrections to the effective potential and,
consequently, to the point particle's motion are obtained. A short analysis on
the asymptotic behavior of the 4-dimensional brane is presented.Comment: 16 pages, LaTeX; (v2) references added and correcte
New Coordinates for de Sitter Space and de Sitter Radiation
We introduce a simple coordinate system covering half of de Sitter space. The
new coordinates have several attractive properties: the time direction is a
Killing vector, the metric is smooth at the horizon, and constant-time slices
are just flat Euclidean space. We demonstrate the usefulness of the coordinates
by calculating the rate at which particles tunnel across the horizon. When
self-gravitation is taken into account, the resulting tunneling rate is only
approximately thermal. The effective temperature decreases through the emission
of radiation.Comment: LaTeX, 10 pages; v2. references added; v3. minor sign errors fixed,
reference added, journal versio
Hawking Radiation from Non-Extremal D1-D5 Black Hole via Anomalies
We take the method of anomaly cancellation for the derivation of Hawking
radiation initiated by Robinson and Wilczek, and apply it to the non-extremal
five-dimensional D1-D5 black hole in string theory. The fluxes of the electric
charge flow and the energy-momentum tensor from the black hole are obtained.
They are shown to match exactly with those of the two-dimensional black body
radiation at the Hawking temperature.Comment: 14 page
What kinds of coordinate can keep the Hawking temperature invariant for the static spherically symmetric black hole?
By studying the Hawking radiation of the most general static spherically
symmetric black hole arising from scalar and Dirac particles tunnelling, we
find the Hawking temperature is invariant in the general coordinate
representation (\ref{arbitrary1}), which satisfies two conditions: a) its
radial coordinate transformation is regular at the event horizon; and b) there
is a time-like Killing vector.Comment: 10 page
Energy and Momentum densities of cosmological models, with equation of state , in general relativity and teleparallel gravity
We calculated the energy and momentum densities of stiff fluid solutions,
using Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum complexes,
in both general relativity and teleparallel gravity. In our analysis we get
different results comparing the aforementioned complexes with each other when
calculated in the same gravitational theory, either this is in general
relativity and teleparallel gravity. However, interestingly enough, each
complex's value is the same either in general relativity or teleparallel
gravity. Our results sustain that (i) general relativity or teleparallel
gravity are equivalent theories (ii) different energy-momentum complexes do not
provide the same energy and momentum densities neither in general relativity
nor in teleparallel gravity. In the context of the theory of teleparallel
gravity, the vector and axial-vector parts of the torsion are obtained. We show
that the axial-vector torsion vanishes for the space-time under study.Comment: 15 pages, no figures, Minor typos corrected; version to appear in
International Journal of Theoretical Physic
Anomalies and Hawking radiation from the Reissner-Nordstr\"om black hole with a global monopole
We extend the work by S. Iso, H. Umetsu and F. Wilczek [Phys. Rev. Lett. 96
(2006) 151302] to derive the Hawking flux via gauge and gravitational anomalies
of a most general two-dimensional non-extremal black hole space-time with the
determinant of its diagonal metric differing from the unity () and use it to investigate Hawking radiation from the Reissner-Nordstrom
black hole with a global monopole by requiring the cancellation of anomalies at
the horizon. It is shown that the compensating energy momentum and gauge fluxes
required to cancel gravitational and gauge anomalies at the horizon are
precisely equivalent to the -dimensional thermal fluxes associated with
Hawking radiation emanating from the horizon at the Hawking temperature. These
fluxes are universally determined by the value of anomalies at the horizon.Comment: 18 pages, 0 figure. 1 footnote and 4 new reference adde
Quantum Gravity and Recovery of Information in Black Hole Evaporation
The Generalized Uncertainty Principle (GUP), motivated by current
alternatives of quantum gravity, produces significant modifications to the
Hawking radiation and the final stage of black hole evaporation. We show that
incorporation of the GUP into the quantum tunneling process (based on the
null-geodesic method) causes correlations between the tunneling probability of
different modes in the black hole radiation spectrum. In this manner, the
quantum information becomes encrypted in the Hawking radiation, and information
can be recovered as non-thermal GUP correlations between tunneling
probabilities of different modes.Comment: 7 pages, no figure, final revisio
Energy distribution in a BTZ black hole spacetime
We evaluate the energy distribution associated with the (2+1)-dimensional
rotating BTZ black hole. The energy-momentum complexes of Landau-Lifshitz and
Weinberg are employed for this computation. Both prescriptions give exactly the
same form of energy distribution. Therefore, these results provide evidence in
support of the claim that, for a given gravitational background, different
energy-momentum complexes can give identical results in three dimensions, as it
is the case in four dimensions.Comment: 16 pages, LaTeX; v2: comments, clarifications and references added,
version to appear in Int.J.Mod.Phys.
Background independent quantization and the uncertainty principle
It is shown that polymer quantization leads to a modified uncertainty
principle similar to that obtained from string theory and non-commutative
geometry. When applied to quantum field theory on general background
spacetimes, corrections to the uncertainty principle acquire a metric
dependence. For Friedmann-Robertson-Walker cosmology this translates to a scale
factor dependence which gives a large effect in the early universe.Comment: 6 page
Transgressing the horizons: Time operator in two-dimensional dilaton gravity
We present a Dirac quantization of generic single-horizon black holes in
two-dimensional dilaton gravity. The classical theory is first partially
reduced by a spatial gauge choice under which the spatial surfaces extend from
a black or white hole singularity to a spacelike infinity. The theory is then
quantized in a metric representation, solving the quantum Hamiltonian
constraint in terms of (generalized) eigenstates of the ADM mass operator and
specifying the physical inner product by self-adjointness of a time operator
that is affinely conjugate to the ADM mass. Regularity of the time operator
across the horizon requires the operator to contain a quantum correction that
distinguishes the future and past horizons and gives rise to a quantum
correction in the hole's surface gravity. We expect a similar quantum
correction to be present in systems whose dynamics admits black hole formation
by gravitational collapse.Comment: 32 pages, 1 eps figure. v2: references and comments adde
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