arXiv subjects

Yongjoon Kwon

Publications and source records attributed to Yongjoon Kwon.

11 recordsLinked to original sources

arXiv2026

A Constraint-Free Formulation of Black Hole Thermodynamics from the Field Equations

We develop a constraint-free formulation that generalizes Padmanabhan's method for deriving the first law of black hole thermodynamics directly from the Einstein field equations. In previous studies, even for multi-horizon black holes, variations were restricted to the outer horizon by imposing an additional constraint, and the PdV term was introduced by multiplying the field equations evaluated at the outer horizon by the corresponding volume variation dV. However, since general variations of the black hole parameters shift both horizons, variations at both horizons must be taken into account. To this end, we propose multiplying the horizon field equations by the entropy variation dS under such unconstrained variations. We show that this method remains valid even in higher-derivative theories of gravity. In addition, we find that $r_{\pm}$-based variation schemes generically break down for black holes characterized by three independent parameters (M,J,Q). By working directly in the thermodynamic state space (M,J,Q), we show that the Einstein field equations evaluated at the outer horizon can be also interpreted as the first law of black hole thermodynamics for general variations without imposing any additional constraints.

gr-qc↗

arXiv2013

Some properties of the de Sitter black holes in three dimensional spacetime

We investigate the physical properties of the de Sitter spacetime and new type-de Sitter black holes in new massive gravity, a higher derivative gravity theory in three dimensions. We calculate thermodynamic quantities and check that the first law of thermodynamics is satisfied. In particular, we obtain the energies of the de Sitter spacetime and new type-de Sitter black holes from the renormalized Brown-York boundary stress tensor on the Euclidean surfaces at late temporal infinity. We also obtain the quasinormal modes and by using them we find that the entropy spectra are equally spaced via semi-classical quantization.

hep-th↗

arXiv2013

Thermodynamics from field equations for black holes with multiple horizons

The first law of black hole thermodynamics can be read off from the field equations at the horizon. Until now, for black holes with multiple horizons the field equations only at the outer horizon were employed with a particular constraint. In this paper, however, we suggest that for a black hole with multiple horizons the field equations at the inner horizon as well as the outer horizon should be needed in order to obtain the first law of black hole thermodynamics in general.

gr-qc↗

arXiv2012

Extremal Black Holes and Holographic C-Theorem

We found Bogomol'nyi type of the first order differential equations in three dimensional Einstein gravity and the effective second order ones in new massive gravity when an interacting scalar field is minimally coupled. Using these equations in Einstein gravity, we obtain analytic solutions corresponding to extremally rotating hairy black holes. We also obtain perturbatively extremal black hole solutions in new massive gravity using these lower order differential equations. All these solutions have the anti de-Sitter spaces as their asymptotic geometries and as the near horizon ones. This feature of solutions interpolating two anti de-Sitter spaces leads to the construction of holographic c-theorem in these cases. Since our lower order equations reduce naturally to the well-known equations for domain walls, our results can be regarded as the natural extension of domain walls to more generic cases.

hep-th↗

arXiv2012

AdS/BCFT Correspondence for Higher Curvature Gravity: An Example

We consider the effects of higher curvature terms on a holographic dual description of boundary conformal field theory. Specifically, we consider three-dimensional gravity with a specific combination of Ricci tensor square and curvature scalar square, so called, new massive gravity. We show that a boundary entropy and an entanglement entropy are given by similar expression with those of the Einstein gravity case when we introduce an {\it effective} Newton's constant and an {\it effective} cosmological constant. We also show that the holographic g-theorem still holds in this extension, and we give some comments about the central charge dependence of boundary entropy in the holographic construction. In the same way, we consider new type black holes and comment on the boundary profile. Moreover, we reproduce these results through auxiliary field formalism in this specific higher curvature gravity.

hep-th↗

arXiv2011

Holographic Renormalization and Stress Tensors in New Massive Gravity

We obtain holographically renormalized boundary stress tensors with the emphasis on a special point in the parameter space of three dimensional new massive gravity, using the so-called Fefferman-Graham coordinates with relevant counter terms. Through the linearized equations of motion with a standard prescription, we also obtain correlators among these stress tensors. We argue that the self-consistency of holographic renormalization determines counter terms up to unphysical ambiguities. Using these renormalized stress tensors in Fefferman-Graham coordinates, we obtain the central charges of dual CFT, and mass and angular momentum of some $AdS$ black hole solutions. These results are consistent with the previous ones obtained by other methods. In this study on the Fefferman-Graham expansion of new massive gravity, some aspects of higher curvature gravity are revealed.

hep-th↗

arXiv2011

Quasi Normal Modes for New Type Black Holes in New Massive Gravity

We obtain the quasi-normal mode frequencies of scalar perturbation on new type black holes in three dimensional new massive gravity. In some special cases, the exact quasi-normal mode frequencies are obtained by solving scalar field equations exactly. On some parameter regions, the highly damped quasi-normal mode frequencies are obtained in an analytic form by the so-called Stokes line method. This study on quasi-normal modes shed some light on the mysterious nature of these black holes. We also comment about AdS/CFT correspondence and the entropy/area spectrum for new type black holes.

hep-th↗

arXiv2011

Entropy spectra of black holes from resonance modes in scattering by the black holes

Since the Bekenstein's proposal that a black hole has equally spaced area spectrum, the quasinormal modes as the characteristic modes of a black hole have been used in obtaining the horizon area spectrum of the black hole. However, the area spectrum of the Kerr black hole in some previous works was inconsistent with the Bekenstein's proposal. In this paper, noting that black holes can have three types of resonance modes which are quasinormal modes (QNM), total transmission modes (TTM), and total reflection modes (TRM), we propose that all of these modes in highly damped regime should be used in quantizing the black hole. Although the QNM and the TTM of the Kerr black hole give us complicated quantization conditions from the Bohr-Sommerfeld quantization of action variable, we find a very simple result from the TRM. It gives equally spaced outer horizon area. Therefore by Bekenstein-Hawking area law we find that the Kerr black hole has universal behavior of the equally spaced entropy spectrum. With the same argument, we find that the Reissner-Nordstrom black hole also has equally spaced entropy spectrum.

hep-th↗

arXiv2010

Quantization of horizon areas of the Kerr black hole

Since the Bekenstein's proposal that a black hole has equally spaced area spectrum, the quasinormal modes as the characteristic modes of a black hole have been used in obtaining the horizon area spectrum of the black hole. However, the area spectrum of the Kerr black hole in some previous works was inconsistent with the Bekenstein's proposal. In this paper, we notice that the Kerr black hole has three types of resonance modes which are quasinormal modes (QNM), total transmission modes (TTM), and total reflection modes (TRM). All of these resonances represent highly damped oscillations and only depend on the black hole parameters which are mass, charge and angular momentum of the black hole. We propose that all of these modes should be used in quantizing the black hole. With all these modes, we find that both the inner and outer horizon areas of the Kerr black hole are equally spaced. Similar behavior is also found in the Reissner-Nordstrom black hole.

hep-th↗

arXiv2010

Area spectra versus entropy spectra in black holes in topologically massive gravity

We consider the area and entropy spectra of black holes in topologically massive gravity with gravitational Chern-Simons term. The examples we consider are the BTZ black hole and the warped AdS black hole. For the non-rotating BTZ black hole, the area and entropy spectra are equally spaced and independent of the coupling constant $\v$ of the Chern-Simons term. For the rotating BTZ black hole case, the spectra of the inner and outer horizon areas are not equally spaced in general and dependent of the coupling constant $\v$. However the entropy spectrum is equally spaced and independent of the coupling constant $\v$. For the warped AdS black holes for $\v >1$ by using the quasinormal modes obtained without imposing the boundary condition at radial infinity we find again that the entropy spectrum is equally spaced and independent of the coupling constant $\v$, while the spectra of the inner and outer horizon areas are not equally spaced and dependent of the coupling constant $\v$. Our result implies that the entropy spectrum has a universal behavior regardless of the presence of the gravitational Chern-Simons term, and therefore it implies that the entropy is more `fundamental' than the horizon area.

hep-th↗

arXiv2010

Area spectra of the rotating BTZ black hole from quasinormal modes

Following Bekenstein's suggestion that the horizon area of a black hole should be quantized, the discrete spectrum of the horizon area has been investigated in various ways. By considering the quasinormal mode of a black hole, we obtain the transition frequency of the black hole, analogous to the case of a hydrogen atom, in the semiclassical limit. According to Bohr's correspondence principle, this transition frequency at large quantum number is equal to classical oscillation frequency. For the corresponding classical system of periodic motion with this oscillation frequency, an action variable is identified and quantized via Bohr-Sommerfeld quantization, from which the quantized spectrum of the horizon area is obtained. This method can be applied for black holes with discrete quasinormal modes. As an example, we apply the method for the both non-rotating and rotating BTZ black holes and obtain that the spectrum of the horizon area is equally spaced and independent of the cosmological constant for both cases.

hep-th↗