Tannukij, Lunchakorn
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Item type:Publication, Rényi Holographic Dark Energy(2024-08-01); Wongjun, PitayuthIn this work, the holographic dark energy model is constructed by using the non-extensive nature of the Schwarzschild black hole via the Rényi entropy. Due to the non-extensivity, the black hole can be stable under the process of fixing the non-extensive parameter. A change undergoing such a process would then motivate us to define the energy density of the Rényi holographic dark energy (RHDE). As a result, the RHDE with choosing the characteristic length scale as the Hubble radius provides the late-time expansion without the issue of causality. Remarkably, the proposed dark energy model contains the non-extensive length scale parameter additional to the standard (Formula presented.) model. The cosmic evolution can be characterized by comparing the size of the Universe to this length scale. Moreover, the preferable value of the non-extensive length scale is determined by fitting the model to recent observations. The results of this work would shed light on the interplay between the thermodynamic description of the black hole with non-extensivity and the classical gravity description of the evolution of the Universe. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effective thermodynamical system of Schwarzschild-de Sitter black holes from Rényi statistics(2021-09-15); Wongjun, PitayuthIt has been known that the Schwarzschild-de Sitter (Sch-dS) black hole may not be in thermal equilibrium and also be found to be thermodynamically unstable in the standard black hole thermodynamics. In the present work, we investigate the possibility to realize the thermodynamical stability of the Sch-dS black hole as an effective system by using the Rényi statistics, which includes the nonextensive nature of black holes. Our results indicate that the nonextensivity allows the black hole to be thermodynamically stable, which gives rise to the lower bound on the nonextensive parameter. By comparing the results to ones in the separated system approach, we find that the effective temperature is always smaller than the black hole horizon temperature and the thermodynamically stable black hole in the effective approach is always larger than the one in the separated approach at a certain temperature. There exists only the zeroth-order phase transition from the hot gas phase to the black hole phase for the effective system, while it is possible to have transitions of both zeroth order and first order for the separated system. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermodynamics of asymptotically de Sitter black hole in dRGT massive gravity from Rényi entropy(2022-12-01); Wongjun, PitayuthThe thermodynamic properties of the de Rham–Gabadadze–Tolley (dRGT) black hole in the asymptotically de Sitter (dS) spacetime are investigated by using Rényi entropy. It has been found that the black hole with asymptotically dS spacetime described by the standard Gibbs–Boltzmann statistics cannot be thermodynamically stable. Moreover, there generically exist two horizons corresponding to two thermodynamic systems with different temperatures, leading to a nonequilibrium state. Therefore, in order to obtain the stable dRGT black hole, we use the alternative Rényi statistics to analyze the thermodynamic properties in both the separated system approach and the effective system approach. Interestingly, we found that it is possible concurrently obtain positive pressure and volume for the dRGT black hole while it is not for the Schwarzschild-de Sitter (Sch-dS) black hole. Furthermore, the bounds on the nonextensive parameter for which the black hole being thermodynamically stable are determined. In addition, the key differences between the systems described by different approaches, e.g., temperature profiles and types of the Hawking–Page phase transition are pointed out. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermodynamics of black holes with Rényi entropy from classical gravity(2025-02-01); Wongjun, PitayuthThe nonextensive nature of black holes is one of the most intriguing discoveries. In fact, the black hole entropy is a nonextensive quantity that scales by its surface area at the event horizon. In our work, we extend the thermodynamic phase space of black holes by treating the nonextensive parameter analyzed via the Rényi entropy as the thermodynamic variable. Using Euler's theorem for a homogeneous function of the black holes' mass, the compatible Smarr formula and the first law of black hole thermodynamics can be obtained. It is also demonstrated that, by keeping the same form of the black hole mass, the Rényi temperature is straightforwardly defined as proposed in the literature. Since many different types of black holes can indeed be successfully treated with such a procedure, our consideration is fairly general. It is worthwhile to argue that the black hole thermodynamics in Rényi statistics is rooted from the relation among geometric quantities in the same way as the standard approach corresponding to the Gibbs–Boltzmann statistics. Even though our results are based on classical gravity, they may pave the way to derive the Rényi temperature using the notion of quantum field in curved spacetime. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Holographic dark energy from the anti-de Sitter black hole(2022-06-15); Wongjun, PitayuthThe anti-de Sitter (AdS) black hole plays an important role in the holographic principle. In this study, the upper bound in energy corresponding to the mass of the Schwarzschild black hole is modified to be that of the AdS black hole. Via the correspondence between the ultraviolet and infrared cutoffs, the constant term in the energy density of the holographic dark energy can be obtained from the negative cosmological constant from the black hole. Interestingly, the proposed dark energy model could drive the late-time expansion of the Universe without the causality violation. The cosmic evolution is investigated by choosing the Hubble and particle horizons as the IR length scales. It is found that the accelerated expansion at late time can be obtained for both cases. The likelihood analysis on the model parameters is also performed. This result may shed light on the connection between the AdS black hole and the de Sitter (dS) spacetime in the context of cosmology.