Myungseok Yoon

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.

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.

Thermodynamic similarity between the noncommutative Schwarzschild black hole and the Reissner-Nordström black hole

We study thermodynamic quantities and examine the stability of a black hole in a cavity inspired by the noncommutative geometry. It turns out that thermodynamic behavior of the noncommutative black hole is analogous to that of the Reissner-Nordstrom black hole in the near extremal limit. Moreover, we identify the noncommutative parameter with the squared electric charge with some constants.

Regular black hole in three dimensions

We find a new black hole in three-dimensional anti-de Sitter space by introducing an anisotropic perfect fluid inspired by the noncommutative black hole. This is a regular black hole with two horizons. We compare the thermodynamics of this black hole with that of a non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein–Hawking entropy.

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 as the thermal flux from each regular black hole at the Hawking temperature.

Entropy of the FRW cosmology based on the brick wall method

The brick wall method in calculations of the entropy of black holes can be applied to the FRW cosmology in order to study the statistical entropy. An appropriate cutoff satisfying the covariant entropy bound can be chosen so that the entropy has a definite bound. Among the entropy for each of cosmological eras, the vacuum energy-dominated era turns out to give the maximal entropy which is in fact compatible with assumptions from the brick wall method.

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 Planck scale to obtain the entropy proportional to the area of the cosmological apparent horizon.

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 a zero angular momentum observer near the horizon. We investigate this with a 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 the absence of the ergoregion. The resulting entropies from the two viewpoints turn out to be the same.

Kerr-Newman-de Sitter solution on DGP brane

Abstract 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.

CHARGED ROTATING BLACK HOLES ON DGP BRANE

We consider charged rotating black holes localized on a three-brane in the DGP model. Assuming a Z2-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.