28 research outputs found
Entropy of Reissner-Nordstrom Black Holes with Minimal Length Revisited
Based on the generalized uncertainty principle, we study the entropy of a
four-dimensional black hole by counting degrees of freedom near the horizon and
obtain the (finite) entropy proportional to the surface area at the horizon
without a cutoff introduced in the conventional brick-wall method.Comment: 5 page
Anomaly and Hawking radiation from regular black holes
We consider the Hawking radiation from two regular black holes, the minimal
model and the noncommutative black hole. The flux of Hawking radiation is
derived by applying the anomaly cancellation method proposed by Robinson and
Wilczek. Two regular black holes have the same radiation pattern except for the
detailed expression for the Hawking temperature. The resulting flux of the
energy-momentum tensor is shown to be precisely the same with the thermal flux
from each regular black hole at the Hawking temperature.Comment: 14 pages, 4 figure
Charged Rotating Black Holes on DGP Brane
We consider charged rotating black holes localized on a three-brane in the
DGP model. Assuming a -symmetry across the brane and with a stationary and
axisymmetric metric ansatz on the brane, a particular solution is obtained in
the Kerr-Schild form. This solution belongs to the accelerated branch of the
DGP model and has the characteristic of the Kerr-Newman-de Sitter type solution
in general relativity. Using a modified version of Boyer-Lindquist coordinates
we examine the structures of the horizon and ergosphere.Comment: LaTeX, 15 pages, Discussion on a bulk solution is adde
Entropy of the FRW universe based on the generalized uncertainty principle
The statistical entropy of the FRW universe described by time-dependent
metric is newly calculated using the brick wall method based on the general
uncertainty principle with the minimal length. We can determine the minimal
length with the Plank scale to obtain the entropy proportional to the area of
the cosmological apparent horizon.Comment: 10 pages, accepted in Modern Physics Letters
Rotating Black Hole Entropy from Two Different Viewpoints
Using the brick-wall method, we study the entropy of Kerr-Newman black hole
from two different viewpoints, a rest observer at infinity and zero angular
momentum observer near horizon. We investigate this with scalar field in the
canonical quantization approach. An observer at infinity can take one of the
two possible frequency ranges; one is with positive frequencies only and the
other is with the whole range including negative frequencies. On the other
hand, a zero angular momentum observer near horizon can take positive
frequencies only. For the observer at infinity the superradiant modes appear in
either choice of the frequency ranges and the two results coincide. For the
zero angular momentum observer superradiant modes do not appear due to absence
of ergoregion. The resulting entropies from the two viewpoints turn out to be
the same.Comment: LaTeX 18 pages, 2 figures, Minor modifications in section 3(ZAMO
Kerr-Newman-de Sitter Solution on DGP Brane
We find an exact solution of Kerr-Newman-de Sitter type on the braneworld(4D)
of the DGP model. When a constant 4D Ricci scalar is assumed, only zero(flat)
and a positive(de-Sitter) values satisfy the Hamiltonian constraint equation
coming from the extra dimension. With a Z_2-symmetry across the brane and a
stationary and axisymmetric metric ansatz on the brane, we solve the constraint
equation exactly in the Kerr-Schild form with de-Sitter background. In the
de-Sitter background this Kerr-Schild solution is well behaved under
Boyer-Lindquist transformation: the constraint equation is preserved under the
transformation and so is the solution. In the non-rotating limit we show that
this Kerr-Newman-de Sitter solution has the characteristic of accelerated
expansion of the braneworld universe.Comment: LaTeX 13 page
Thermodynamics of a black hole based on a generalized uncertainty principle
We study thermodynamic quantities and the stability of a black hole in a
cavity using the Euclidean action formalism by Gibbons and Hawking based on the
generalized uncertainty relation which is extended in a symmetric way with
respect to the space and momentum without loss of generality. Two parameters in
the uncertainty relation affect the thermodynamical quantities such as energy,
entropy, and the heat capacity. In particular, it can be shown that the small
black hole is unstable and it may decay either into a minimal black hole or a
large black hole. We discuss a constraint for a large black hole comparable to
the size of the cavity in connection with the critical mass.Comment: 12 pages, 4 figures; v2. to appear in JHE