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Chen-Hao Hao

Publications and source records attributed to Chen-Hao Hao.

12 recordsLinked to original sources

Learning Boson Star Solution Families with Physics-Informed Neural Networks

Computing boson star families traditionally requires repeated solution of nonlinear eigenvalue boundary-value problems and careful numerical continuation through turning points. We develop a physics-informed neural network (PINN) that learns the map from the physical parameters and radial coordinate directly to the scalar and metric fields over an equilibrium solution manifold. Regularity and asymptotic boundary conditions are incorporated into the network output, while the training objective combines pointwise supervision, Einstein-Klein-Gordon residuals, and curve-level constraints on the Arnowitt-Deser-Misner mass and Noether charge. A trained model generates a complete configuration in a single forward pass. Across representative one-, two-, and three-branch families, the method reconstructs the mass-frequency spirals and conserved quantities, including configurations on inner branches that require delicate continuation in conventional solvers. These results establish physics-informed surrogate learning as a practical route to amortized exploration of nonlinear self-gravitating solution families.

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Radial spectra and dynamical signatures of excited boson stars

We compute the lowest radial mode of spherically symmetric boson stars along equilibrium branches with a fixed number of radial nodes, considering both mini boson stars and quartically self-interacting models. By reformulating the pulsation equations in additive variables that remain regular at the zeros of the background scalar field, the eigenvalue problem can be integrated directly through the nodes of excited configurations. For all branches examined, the first zero of the constrained fundamental radial eigenvalue coincides, within numerical resolution, with the first simultaneous critical point of the Arnowitt--Deser--Misner (ADM) mass, Noether charge, and binding energy. We further evaluate the radial eigenvalue for the threshold models identified in nonlinear spherical evolutions of excited boson stars and find a simple empirical correlation with the node number and self-interaction strength. Our results provide a regular perturbative framework for excited boson stars and clarify the relation between constrained radial modes, equilibrium critical points, and nonlinear stability diagnostics.

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Off-shell Hessian thermodynamic stability of higher-curvature black holes

We develop a branch-sensitive thermodynamic framework for higher-curvature black holes using the off-shell Gibbs free energy $G_{\rm off}$ and the Wald entropy$S_W$ as the basic data. On fixed-parameter slices, equilibrium black holes are stationary points of $G_{\rm off}$, and their local stability is governed by the Hessian $H=S'_W(r_h)T'(r_h)$, rather than by the temperature slope alone. For the five-dimensional charged regular AdS black hole in quasi-topological gravity, $S_W$ remains monotonic on the physical branch, so the usual temperature-slope rule is recovered only as a special consequence. The same off-shell structure also gives the local $A_3$ cusp normal form near criticality, yielding the mean-field $1/2$ branch separation exponent and explaining why smooth nondegenerate observables, such as the Lyapunov exponent, inherit the same scaling. In Lovelock black holes, $S'_W$ can change sign on non-planar branches, reversing the temperature slope stability assignment. However, on ghost-free and branch-regular Lovelock exteriors $S'_W$ remains positive. Thus the off-shell Hessian criterion also diagnoses why the ordinary slope rule is protected on physically admissible black holes branches.

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Proca-Maxwell System in an Infinite Tower of Higher-Derivative Gravity

We numerically construct a five-dimensional Proca-Maxwell system coupled to an infinite tower of higher-derivative gravity, parameterized by the correction order and coupling constant. While the first-order correction case recovers standard Einstein gravity results, and the second-order correction (Gauss-Bonnet) case fails to resolve the central singularity in the vanishing frequency limit, we demonstrate that higher-order corrections effectively regularize the spacetime, yielding globally regular solutions. A key finding is the emergence of a ``frozen state'' in the supercritical regime: as the field frequency approaches zero, matter concentrates entirely within a critical radius, creating a regular core that externally mimics an extremal black hole. We further reveal that introducing the electric charge fundamentally alters this behavior; the electrostatic repulsion counteracts the gravitational collapse, effectively ``unfreezing'' the system and preventing the formation of the critical core. Significantly, unlike models relying on exotic matter, our solutions satisfy all standard energy conditions across the entire parameter space, establishing a physically viable pathway for constructing regular black hole mimickers.

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Charged Regular Black Holes From Quasi-topological Gravities in $D\ge 5$

The investigation of gravity in higher-dimensional spacetime has transitioned from a mathematical curiosity to a fundamental framework in theoretical physics, catalyzed by the dimensional requirements of String theory and M-theory. In this paper, we explicitly construct a spherically symmetric charged black hole solution in $D \ge 5$ dimensions within a gravity theory featuring an infinite tower of higher-curvature corrections. For a given mass and electric charge, the model admits a unique static spherically symmetric solution. We demonstrate that, with an appropriate choice of coupling coefficients $α_n$, the central singularity is progressively mitigated as the correction order increases, ultimately resolving into a globally regular spacetime in the limit of infinite-order corrections. Furthermore, the criteria for the existence of extremal black holes are determined.

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Axion boson stars with wormhole topology

We investigate a novel gravitational configuration formed by a massless real phantom field and an axion scalar field, minimally coupled to gravity. This system describes an Ellis-type wormhole situated at the center of an axion star. By normalizing the mass of the axion field to unity, the physical properties of the model are determined by three independent parameters: the potential's decay constant, the frequency of the axion field, and the wormhole's throat parameter. We assess the traversability of this wormhole by examining the curvature scalars and energy conditions of the static solution. Our analysis of the wormhole's embedding diagrams indicates that, although the wormhole typically exhibits a single-throat geometry, a double-throat configuration featuring an equatorial plane may arise under specific conditions. Finally, an analysis of the null-geodesics reveals the existence of at least one unstable light ring at the wormhole throat.

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Proca stars in AdS Ellis wormholes

In this paper, we study Proca stars in asymptotically anti-de Sitter (AdS) Ellis wormholes. This study distinguishes itself from the analysis of the Proca stars in asymptotically flat spacetimes. In the AdS Ellis wormhole background, the mass of the wormhole solutions vanishes. Consequently, we employ numerical techniques to investigate in detail the impact of the cosmological constant on both the matter field and the wormhole geometry, while categorizing the solutions in accordance with the symmetries of the Proca field. The results show that when the cosmological constant decreases, not only does the characteristic spiral behavior of the Proca star solutions, namely the charge-frequency relation $Q$-$ω$, gradually disappear, but the throat or both sides of the wormhole may also develop a ``horizon", presenting a ``black bounce" characteristic.

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Ellis wormhole with nonlinear electromagnetic field

In this paper, we present the spherically symmetric wormhole in Einstein's gravity coupling phantom field and nonlinear electromagnetic field. Numerical results show that this solution violates the Null Energy Condition (NEC), and as the parameters change, the ADM mass of the entire spacetime changes from positive to negative. In addition, we analyze the light ring (LR) of the solution and demonstrate the astronomical observation properties. Especially when negative mass appears, the general LR will not appear, only a ``special unstable LR" exists at the throat, which is caused by the repulsive effect of the negative mass on both sides of the wormhole. Finally, we draw the embedding diagram to reflect the geometric characteristics of the wormhole.

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AdS Ellis wormholes with scalar field

In this paper, we study the spherically symmetric traversable wormholes with a scalar field supported by a phantom field in the anti-de Sitter (AdS) asymptotic spacetime. Despite coupling the scalar matter field, these wormholes remain massless and symmetric for reflection of the radial coordinate $r \rightarrow -r$. The solution possesses a finite Noether charge $Q$, which varies as a function of frequency $ω$ with changes in the cosmological constant $Λ$ and the throat size $r_0$. Under specific conditions, an approximate ``event horizon'' will appear at the throat.

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Emergence of Negative Mass in General Relativity

We develop a symmetric traversable wormhole model, integrating Einstein's gravitational coupling phantom field and a nonlinear electromagnetic field. This work indicates the emergence of negative ADM mass within a specific parameter range, coinciding with distinct alterations in the wormhole's spacetime properties. Despite violating the Null Energy Condition (NEC) and other energy conditions, the solution exhibits unique characteristics in certain energy-momentum tensor components, potentially accounting for the manifestation of negative mass.

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Building a black hole-wormhole-black hole combination

In this paper, we present the spherically symmetric Proca star in the presence of a phantom field and obtain a traversable wormhole solution for non-trivial topological spacetime. Using numerical methods, symmetric solutions and asymmetric solutions are obtained in two asymptotically flat regions. We find that when changing the throat size $r_{0}$, both the mass $M$ and the Noether charge $Q$ no longer have the spiral characteristics of an independent Proca star, furthermore, the asymmetric solution can be turned into the symmetric solution at some frequency $ω$ in certain $r_{0}$. In particular, we find that when the frequency takes a certain value, for each solution, there is an extremely approximate black hole solution, and there is even a case where an event horizon appears on both sides of the wormhole throat.

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Emergency of black holes from wormholes

In this paper, we study the spherically symmetric Dirac star model in the presence of a phantom field, obtaining a traversable wormhole solution in non-trivial topological spacetime. This solution exhibits asymmetry in both the field configuration and the metric and possesses a finite ADM mass $M$ and Noether charge $Q$. Furthermore, we find that due to the presence of a wormhole at the center, this solution exhibits many differences from the Dirac star under trivial spacetime. Notably, when the wormhole throat size is small, our numerical calculations indicate the emergence of an extremely approximate black hole solution on one side of the wormhole spacetime, a phenomenon unexplored. At this time, the Kretschmann scalar near the throat tends to infinity, indicating the wormhole becomes untraversable.

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