arXiv subjects

Yu-Die Wan

Publications and source records attributed to Yu-Die Wan.

6 recordsLinked to original sources

arXiv2026

Novel thermodynamic topological subclass from inverse-temperature asymptotics

We investigate the thermodynamic topology of the charged McGuigan--Nappi--Yost black hole in the canonical ensemble at fixed electric charge, identifying equilibrium black hole solutions as zeros of the thermodynamic vector field constructed from the generalized off-shell free energy. The inverse Hawking temperature diverges as the extremal limit is approached and approaches a finite positive value in the large-horizon limit. The zero points of the thermodynamic vector field reveal a thermodynamic phase structure consisting solely of a locally stable branch with positive winding number ($w=+1$). The innermost small black hole state is locally stable in the low-temperature limit. As the temperature increases, the stable branch extends toward the outermost large black hole regime, while no black hole states exist in the high-temperature regime beyond the finite upper Hawking temperature. This distinct asymptotic behavior of the inverse temperature places the thermodynamic defect structure outside the established topological (sub)classes, although its topological number agrees with that of the standard $W^{1+}$ class. We therefore identify this defect structure as a new thermodynamic topological subclass, $\breve W^{1+}$. This finding extends the existing classification to include a finite, nonzero large-horizon limit of the inverse Hawking temperature and suggests that distinct asymptotic behaviors in other black hole families may reveal further topological (sub)classes and thermodynamic phase structures.

gr-qc↗

arXiv2026

Novel topological subclasses of a magnetic black hole in causal nonlinear electrodynamics

By treating black-hole states as topological defects in thermodynamic parameter space, we investigate a static, asymptotically flat magnetic black holes in Einstein gravity coupled to causal nonlinear electrodynamics. Using the generalized off-shell free energy and Duan's $ϕ$-mapping topological current theory, we analyze the physical single-horizon sector in the canonical ensemble. We identify four representative defect-curve profiles, including realizations of the conjectured $W^{0+\leftrightarrow1-}$ class and $\overline{W}^{1-}$ subclass, as well as a new thermodynamic topological subclass, $\overline{W}^{0+\leftrightarrow1-}$. This new subclass features paired generation and annihilation points, with unstable innermost and outermost branches. As the auxiliary inverse temperature increases, the system evolves from two equilibrium states to three and then back to one, with an unstable small-black-hole defect entering through the physical lower boundary and changing the global topological number from $W=0$ to $W=-1$. This boundary-induced change signals a thermodynamic topological phase transition. These results show that the same inverse-temperature endpoint behavior and winding-number sequence from small to large black holes can accompany different defect evolution, highlighting the role of the physical horizon boundary in thermodynamic topological classification. More broadly, this causal nonlinear-electrodynamics black-hole family provides a setting for discovering further defect structures and thermodynamic topological phase transitions.

gr-qc↗

arXiv2026

Thermodynamic topological classification of magnetically charged slowly rotating Kerr black holes in nonlinear electrodynamics with a cosmological constant

We provide an explicit rotating black-hole realization of the predicted $\overline{W}^{1-}$ thermodynamic topological subclass by studying a slowly rotating, magnetically charged Kerr black hole in nonlinear electrodynamics (NLED). Using a reduced fixed-parameter off-shell potential, we derive the inverse-temperature curve analytically rather than relying solely on numerical plots. In AdS spacetime, this curve begins at a finite nonzero value, increases monotonically, and diverges at large horizon radius; it therefore contains exactly one defect with $w=W=-1$ and has no stable large-black-hole branch. Positivity of the analytic coefficient establishes this result throughout the admissible slow-rotation parameter domain. Under the same reduced prescription, the Kerr-AdS benchmark instead has two branches and belongs to the $W^{0-}$ class, establishing a clear topological distinction between the NLED-Kerr and classical rotating cases. In dS spacetime, the formally extended off-shell curve remains monotonic and any isolated zero has $w=-1$; because the parameter-dependent horizon-admissible range is not fixed in the present reduced analysis, no physical dS asymptotic subclass is assigned.

gr-qc↗

arXiv2026

Thermodynamic topology of magnetic GMGHS black holes: the $\overline {W}^{1-}$ subclass

Thermodynamic topology provides a topological classification of black hole states and their branch structures in thermodynamic parameter space. We investigate the thermodynamic topology of the charged nonextremal magnetic Gibbons--Maeda family in four-dimensional asymptotically flat Einstein--Maxwell--dilaton gravity, with particular emphasis on its string-theory member at the dilaton coupling $a=1$, the Gibbons--Maeda--Garfinkle--Horowitz--Strominger (GMGHS) black hole. An analytic classification over the complete domain of regular outer horizons shows that the dilaton coupling separates the family into three limiting structures of the inverse Hawking temperature. At $a=1$, the GMGHS defect curve approaches a nonzero lower inverse temperature endpoint and contains a single unstable branch. In particular, the magnetic GMGHS black hole provides an explicit realization of the previously proposed $\overline W^{1-}$ thermodynamic topological subclass within an asymptotically flat Einstein--Maxwell--dilaton solution. This result demonstrates that the global topological number $W$ alone does not completely characterize black hole thermodynamic topology. The asymptotic behavior of the inverse Hawking temperature near the boundaries of the physical horizon domain provides an additional criterion for distinguishing thermodynamic topological subclasses with the same $W$.

gr-qc↗

arXiv2026

Novel topological subclass in Bardeen-AdS-class black holes

Based on the $ϕ$-mapping topological current theory, we systematically investigate the thermodynamic topology of regular Bardeen-AdS-class black holes coupled to nonlinear electrodynamics, a class of singularity-free geometries whose topological classification remains underexplored. We implement numerical calculations at two typical AdS radii $L=1$ and $L=15$. Within the fundamental $W^{0-}$ topological family, we identify a novel inner secondary subclass $\widetilde{W}^{0-}$. This result only refines and enriches the internal branch structure of the $W^{0-}$ family under the established classification scheme of five topological classes and four topological subclasses for black hole thermodynamics. This new subclass has a vanishing global topological charge $W=0$ with an inner-outer horizon winding-number signature $[-,+]$. Unlike standard $W^{0-}$ solutions that realize topological extension via embedded $(+,-)$ winding pairs, $\widetilde{W}^{0-}$ arises from attaching an extra stable branch to the end of the base solution sequence. Two critical coupling parameters $\hat{m}_{01}$ and $\hat{m}_{02}$ divide the full parameter space into distinct topological phases: Type I black holes with $m_0\ge\hat{m}_{01}$ and Type II solutions with $\hat{m}_{02}<m_0<\hat{m}_{01}$ belong to $\widetilde{W}^{0-}$, while the parameter region $0<m_0\le\hat{m}_{02}$ corresponds to the conventional $W^{0-}$ topology. Our numerical results verify the self-consistency of the thermodynamic topological formalism when applied to singularity-free regular black holes, refine the topological discrimination criteria tailored to nonlinear-electrodynamics regular black holes, and provide theoretical references for subsequent topological investigations of higher-dimensional rotating regular black holes under the same formalism.

gr-qc↗

arXiv2026

Universal Thermodynamic Topological Classes of BTZ Black Holes in Einstein and F(R) Gravity

In this paper, we systematically study three classes of three-dimensional Bañados-Teitelboim-Zanelli (BTZ) black holes based on different gravitational frameworks and matter field structures: the Einstein-Maxwell BTZ, the F(R)-Maxwell BTZ, and the F(R)-phantom BTZ.Within the canonical and grand canonical ensemble frameworks, we construct the generalized free energy of these black hole systems and systematically analyze the asymptotic behavior of Hawking thermodynamics.The results indicate that both gravitational modifications and matter fields significantly influence black hole topology: the F(R) gravitational modification alters the intrinsic topological class of the black hole compared to the BTZ black hole under Einsteinian gravity, while different matter fields further modulate the topological classification results. Furthermore, by comparing the two types of ensembles, we find significant differences in black hole topological classes, and these differences are correlated with the gravitational framework and matter fields. In summary, the gravitational framework, matter fields, and ensemble selection are key factors governing the topological classification of black holes; all identified topological categories belong to the existing three-dimensional spacetime topological classification system, highlighting their universality. This work deepens our understanding of the thermodynamic-topological connection in three-dimensional BTZ black holes and provides a rigorous theoretical foundation for extending such topological classifications to modified gravity theories and different matter field backgrounds.

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