arXiv subjects

Qing-Quan Jiang

Publications and source records attributed to Qing-Quan Jiang.

At least 19 recordsLinked to original sources

arXiv2026

Globally regular charged black holes in non-polynomial quasi-topological gravity with Born-Infeld electrodynamics

We construct exact static, spherically symmetric charged solutions in four-dimensional non-polynomial quasi-topological gravity coupled to Born-Infeld electrodynamics. We focus on the model $h(p)=p/(1+\ell^{2}p)$, whose vacuum branch develops a curvature singularity at a finite radius. We show that Born-Infeld nonlinearities can remove this singularity within a finite region of parameter space, yielding globally regular geometries with an asymptotically flat exterior and a finite-curvature AdS-type core. The regular sector contains both horizonless configurations and RBHs, separated by a degenerate-horizon boundary. We further identify a continuous branch of regular black holes with a triple-degenerate inner horizon and a simple outer event horizon, satisfying $κ_-=0$ and $κ_+\neq0$. These results provide a converse example to cases in which introducing charge spoils the regularity of a black hole that is regular in vacuum. In the present model, Born-Infeld electrodynamics instead removes the finite-radius singularity of a gravitational branch that is singular in vacuum and supports globally regular charged geometries, including regular black holes with nontrivial inner-horizon structure.

gr-qc↗

arXiv2026

Optical Images of the Braneworld Black Hole Surrounded by an Optically Thin Accretion Disk

This work examines the observational signatures of rotating black holes with tidal charge in the Randall--Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld black holes in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strongly asymmetric image morphology. We show that the image asymmetry and the deformation of the inner shadow are jointly controlled by the black hole spin, the tidal charge, and the observer inclination. To analyze the frequency shifts across the accretion disk, we extend the emitting region from the ISCO down to the event horizon by including the plunging flow. The results indicate that the observer inclination is the dominant factor governing the frequency-shift distribution. In addition, we reconstruct braneworld black hole images using a fisheye-lens ray-tracing model. The optical morphology and brightness distribution show a clear dependence on the observing frequency, especially when comparing 230~GHz with 86~GHz. We also contrast the brightness distributions of prograde and retrograde disks, finding that both the total intensity and the peak intensity at 86~GHz are higher than those at 230~GHz. For negative values of the tidal charge, we further investigate the corresponding frequency-shift behavior and 230~GHz intensity profiles, which may provide useful theoretical guidance for future studies of extra-dimensional gravity models.

astro-ph.HE↗

arXiv2026

Coherent multipath wave response on Reissner-Nordström analogue surface

To uncover how the intrinsic metric of a relativistic compact object governs macroscopic wave phenomena, we establish a theoretical framework mapping the charge dependent spatial geometry of a Reissner-Nordström (RN) black hole onto the coherent response of an analogue curved surface. By solving an exact spatial geodesic boundary value problem on an isometrically embedded equatorial slice, we extract the discrete multi-loop path-length spectrum and convert this geometric backbone into a physical wave field via a finite-path surface Huygens-Fresnel construction. We analytically compute the arbitrary order winding trajectories alongside their high winding accumulation limits, demonstrating that the analogue charge acts as a precise physical dial that reconfigures the event horizon throat and fundamentally reorganizes the discrete path sequence. Furthermore, we find that this underlying geometric deformation uniquely dictates the macroscopic interference, revealing that steady state spatial fringes, spectral resonance combs, and transient temporal echo ladders are intrinsically unified physical projections of a single charge controlled path spectrum. This systematic parameter to response methodology establishes a rigorous theoretical bridge between strong field gravitational lensing and tabletop transformation optics, providing a highly tunable blueprint for future multi domain analogue gravity experiments.

gr-qc↗

arXiv2026

Regular black hole with sub-Planckian curvature and suppressed exponential mass inflation

We construct a static spherically symmetric regular black hole with a Minkowski core, and a degenerate inner horizon with vanishing surface gravity. The spacetime contains a non-extremal outer horizon and exhibits two notable features. Firstly, in the large-mass regime with $r_+=2M$, the Kretschmann scalar becomes nearly independent of the ADM mass and is mainly controlled by the inner horizon radius $r_-$, so that the curvature of spacetime remains sub-Planckian everywhere by choosing $r_-$ appropriately. Secondly, the near inner horizon amplification is softened from exponential to power-law behavior. In particular, within the double-null shell and Ori models, the internal Misner-Sharp mass remains finite at late times and approaches $r_-/2$.

gr-qc↗

arXiv2026

Polarized Radiative Transfer of Kerr-Newman Black Hole

In this analysis, we investigate the polarization radiation imaging of Kerr-Newman black holes, with a particular focus on the impact of black hole charge on photon propagation and polarization characteristics. By extending the traditional Walker-Penrose method, which is limited by its reliance on specific symmetric structures and Killing tensors, we overcome these limitations by constructing an ordinary differential equations (ODEs) numerical framework that combines the photon orbit equation with the polarization parallel transport equation. This allows for the self-consistent evolution of photon trajectories and polarization states in any spacetime backgrounds without relying on specific symmetries. Using this framework, we analyze the effects of black hole spin and charge on the polarization characteristics of radiation from both prograde and retrograde accretion disks. Our results show that black hole charge can significantly modify photon trajectories and polarization patterns: increasing charge compresses and distorts the EVPA structure on photon-ring scales, inducing localized rotations and asymmetries that may provide a potential diagnostic of a nonzero black hole charge.

gr-qc↗

arXiv2026

Krylov complexity and Wightman power spectrum with positive chemical potential in Schrödinger field theory

We study Krylov complexity in Schrödinger field theory in the grand canonical ensemble with chemical potential $μ$, with an emphasis on the qualitatively new features that arise for $μ>0$. In this regime the fermionic Wightman power spectrum is effectively single-sided and sharply truncated at $ω=μ$, which induces a crossover in the Lanczos coefficients {and signals a dynamical transition from a bulk-dominated regime to a spectral-edge-dominated regime}: $b_n$ displays a two-stage linear growth (from an early-time slope $π/β$ to an asymptotic slope $2/β$), while $a_n$ bends from near-zero values to a linear descent with slope $-4/β$. We provide analytic support for the resulting complexity growth from three complementary viewpoints: (i) using an $SL(2,\mathbb{R})$ algebraic construction matched to the asymptotic Lanczos data, we show that the late-time Krylov complexity must grow quadratically, $K(t)\propto t^{2}$; (ii) by analyzing engineered Wightman spectra with controlled decay and truncation, we identify single-sided exponential decay as the key spectral feature responsible for the quadratic asymptotics, while an approximately even two-sided exponential spectrum explains the early-time $K(t)\sim\sinh^{2}(πt/β)$ behavior at large $μ$; (iii) we formulate the problem in terms of orthogonal polynomials and estimate the crossover scale separating the early- and late-stage regimes. Overall, our results help clarify the role of chemical potential and spectral truncation in shaping operator growth and Krylov complexity in this non-relativistic quantum field theory setting.

hep-th↗

arXiv2025

The stochastic gravitational wave background from QCD phase transition in the framework of higher-order GUP

This work studies the impact of a new higher-order generalized uncertainty principle (GUP) on the stochastic gravitational wave background (SGWB) associated with a QCD-scale first-order phase transition. Assuming a strongly first-order transition at the QCD-scale as a phenomenological benchmark, the analysis shows that the sign and magnitude of the dimensionless deformation parameter $β_0$ play a crucial role. For negative $β_0$, the thermodynamic quantities of the radiation fluid develop a maximal temperature beyond which entropy and pressure vanish, and the SGWB spectrum exhibits divergent behavior at high temperatures, so this branch is discarded as phenomenologically inconsistent. For positive $β_0$, the higher-order GUP shifts the SGWB peak frequency towards lower values and slightly enhances the peak energy density, with the size of the effect controlled by $β_0$. For natural values $β_0=\mathcal{O}\left( 1 \right)$ the corrections at QCD temperatures are strongly suppressed, whereas larger benchmark values still compatible with existing experimental and cosmological bounds can induce appreciable shifts in the SGWB spectrum. A future detection of a QCD-scale first-order SGWB would therefore allow the framework developed here to be used to translate the measured signal into constraints on the higher-order GUP parameter, providing an indirect probe of quantum gravity effects.

gr-qc↗

arXiv2025

Cosmological Model Independent Constraints on Lorentz Invariance Violation with Updated Gamma-Ray Burst Observations: An Artificial Neural Network Approach

Searching for Lorentz invariance violation (LIV) using astrophysical sources such as gamma-ray bursts (GRBs) is crucial for probing quantum gravity. However, the dependence of LIV constraints on assumed cosmological models has been largely overlooked. In this work, we present a model-independent reconstruction of the cosmic expansion history using artificial neural networks (ANN), thereby avoiding biases from specific cosmological priors. We analyze 74 GRB time delays, including 37 measurements from GRB~160625B across multiple energy bands at $z = 1.41$, and 37 additional bursts spanning redshifts $0.117 \leq z \leq 1.99$. Our analysis yields stringent constraints on both linear and quadratic LIV, with $E_{\mathrm{QG},1} \geq 2.60 \times 10^{15}~\mathrm{GeV}$ and $E_{\mathrm{QG},2} \geq 1.21 \times 10^{10}~\mathrm{GeV}$. The linear limit is within four orders of magnitude of the Planck scale. By leveraging a large sample of GRBs, our approach significantly enhances the robustness of LIV constraints, providing a powerful, cosmological-independent framework for future tests of quantum gravity.

astro-ph.HE↗

arXiv2025

Image of a time-dependent rotating regular black hole

In this study, we develop a modeling framework based on spatio-temporal generalized random fields to simulate the time-evolving accretion flows and their associated imaging signatures around rotating regular black holes. We extend the Matérn field formalism to the spatio-temporal domain and introduce a locally anisotropic tensor structure $Λ(\mathbf{x})$, which encodes direction-dependent correlation scales motivated by Keplerian velocity fields, thereby generating physically informed perturbation structures. Coupled with a computationally efficient light ray-tracing scheme, this framework produces a sequence of time-resolved images of regular black hole shadow and accretion structures. By incorporating light-travel time effects, we identify significant temporal smearing of features within strongly lensed regions and rapidly varying sources, thus enhancing the physical realism of the modeling. Comparison with existing general relativistic magnetohydrodynamic simulations demonstrates that our stochastic generative model maintains statistical consistency while offering substantial computational efficiency. Moreover, the simulated results reproduce the dynamic positional shift of the bright ring structure observed in M87$^{*}$, providing theoretical support for interpreting its time-variable images.

astro-ph.HE↗

arXiv2025

Optical images of the Kerr-Sen black hole and thin accretion disk

This paper investigates the observable properties of a Kerr-Sen black hole surrounded by a thin accretion disk, focusing on the impact of the black hole's spin and charge on the image. Using ray-tracing techniques, we conduct a detailed analysis of the black hole's image, redshift distribution, and intensity distributions at different observation frequencies. The results demonstrate that spin has a more significant effect on the distortion of the inner shadow than charge, and the observer's inclination angle plays a critical role in shaping the redshift distribution, especially near the innermost stable circular orbit. Additionally, the intensity is found to be higher at 86 GHz than at 230 GHz. This study highlights the crucial role of the accretion disk's geometry in determining the black hole's image and redshift effects, thereby providing a refined theoretical framework to guide future observational efforts targeting the Kerr-Sen black hole and its electromagnetic signals.

gr-qc↗

arXiv2025

Observational features of massive boson stars with thin disk accretion

In this paper, based on the action of a complex scalar field minimally coupled to a gravitational field, we numerically obtain a series of massive boson star solutions in a spherically symmetric background with a quartic-order self-interaction potential. Then, considering a thin accretion flow with a certain four-velocity, we further investigate the observable appearance of the boson star using the ray-tracing method and stereographic projection technique. As a horizonless compact object, the boson star's thin disk images clearly exhibit multiple light rings and a dark central region, with up to five bright rings. As the observer's position changes, the light rings of some boson stars deform into a symmetrical "horseshoe" or "crescent" shape. When the emitted profile varies, the images may display distinct observational signatures of a "Central Emission Region". Meanwhile, it shows that the corresponding polarized images not only reveal the spacetime features of boson stars but also reflect the properties of the accretion disk and its magnetic field structure. By comparing with black hole, we find that both the polarized signatures and thin disk images can effectively provide a possible basis for distinguishing boson stars from black holes. However, within the current resolution limits of the Event Horizon Telescope (EHT), boson stars may still closely mimic the appearance of black holes, making them challenging to distinguish at this stage.

gr-qc↗

arXiv2025

Symmetric black-to-white hole solutions with a cosmological constant

For a system with a Hamiltonian constraint, we demonstrate that its dynamics is invariant under different choices of the lapse function, regardless of whether the Hamiltonian incorporates quantum corrections. Applying this observation to the interior of black-to-white holes, we analyze its dynamics with different choices of the lapse function. The results explicitly show that the leading-order expansion of both metrics proposed by Rovelli et al. (Class. Quant. Grav. \textbf{35}, 225003 (2018); Class. Quant. Grav. \textbf{35}, 215010 (2018)) and Ashtekar et al. (Phys. Rev. Lett. \textbf{121}, 241301 (2018); Phys. Rev. D \textbf{98}, 126003 (2018)) exhibit identical behavior near the transition surface. Therefore, in this sense the black-to-white hole model proposed by Rovelli et al., (Class. Quant. Grav. \textbf{35}, 225003 (2018); Class. Quant. Grav. \textbf{35}, 215010 (2018)) may be interpreted as a coarse-grained version of the solution within the framework of loop quantum gravity. The black-to-white hole solutions with exact symmetry between the black hole and white hole regions are constructed by appropriately fixing the quantum parameters in the effective theory of loop quantum gravity. This approach circumvents the issue of amplification of mass, which could arise from a mass difference between the black hole and white hole, and provides a way to link the solutions obtained by minisuperspace quantization to those in the covariant approach. Finally, the black-to-white hole solutions with a cosmological constant are constructed. The numerical solutions for the interior of the black-to-white hole with a cosmological constant are obtained, and their symmetric behavior is also discussed.

gr-qc↗

arXiv2025

Correspondence between grey-body factors and quasinormal modes for regular black holes with sub-Planckian curvature

We investigate the quasi-normal modes (QNMs) under the gravitational field perturbations and the grey-body factors for a class of regular black holes with sub-Planckian curvature and Minkowski core. Specifically, we compute the QNMs with the pseudospectral method and the WKB method. It is found that as the deviation parameter of the regular black hole changes, the trajectory of the QNMs displays non-monotonic behavior. Then we compute the grey-body factors with the WKB method and compare them with the results obtained by the correspondence relation recently revealed in [1]. We find the discrepancy exhibits minimor errors, indicating that this relation is effective for computing the grey-body factors of such regular black holes.

gr-qc↗

arXiv2025

Shadows and accretion disk images of charged rotating black hole in modified gravity theory

In this paper, we study the shadow and images of the accretion disk of Kerr-Newman (KN) black hole (BH) in modified gravity (MOG) theory by using backward ray-tracing method. And, the influence of spin parameter ($a$), charge ($Q$), and MOG parameter ($α$) on the observed features of BHs are carefully addressed. Interestingly, as $α$ increases, the flat edge of the BH's shadow gradually becomes more rounded, the size of shadow enlarges, and the deviation rate ($δs$) correspondingly decreases. By tracing the photon around BH, we observe that the trajectory of photon exhibits distortion behavior, i.e., the formation of two "tails" near the Einstein ring, which elongate as $a$ increases. For the accretion disk, it shows that the inner shadow expands with $α$, while decreases with $Q$. The increase of $α$ exhibits an increasing effect on redshift. At the same parameter level, $α$ has a more obvious effect on inner shadow and image of BH by comparing with that of $Q$. Our study implies that both $α$ and $Q$ have relatively significant effects on the image of the KN-MOG BH with the thin disk accretion, but the influence of $α$ is much greater. So, this indicates that $α$ plays a dominant role in this spacetime.

gr-qc↗

arXiv2024

Image of the Kerr-Newman black hole surrounded by a thin accretion disk

The image of a Kerr-Newman (KN) black hole (BH) surrounded by a thin accretion disk is derived. By employing elliptic integrals and ray-tracing methods, we analyze photon trajectories around the KN BH. At low observation inclination angles, the secondary image of particles is embedded within the primary image. However, as the inclination increases, the primary and secondary images separate, forming a hat-like structure. The spin and charge of the BH, along with the observer's inclination angle, affect the image's asymmetry and the distortion of the inner shadow. To investigate the redshift distribution on the accretion disk, we extended the inner boundary of the accretion disk to the event horizon. The results show that the redshift distribution is significantly influenced by the observation inclination angle. Furthermore, we conducted a detailed analysis of the KN BH image using fisheye camera ray-tracing techniques and found that the optical appearance and intensity distribution of the BH vary at different observation frequencies (specifically at 230GHz and 86GHz). We also examined differences in intensity distribution for prograde and retrograde accretion disk scenarios. Comparing observational at the two frequencies, we found that both the total intensity and peak intensity at 86GHz are higher than those at 230GHz.

astro-ph.HE↗

arXiv2024

Quasinormal modes of regular black holes with sub-Planckian curvature and Minkowskian core

We investigate the perturbation of the scalar field as well as the electromagnetic field over a sort of regular black holes which are characterized by the sub-Planckian curvature and the Minkowskian core. Specifically, we compute the quasinormal modes(QNMs) by employing the pseudo-spectral method. The outburst of overtones is manifestly observed in the QNMs of these regular black holes, which can be attributed to the deviation of the Schwarzschild black hole by quantum effects of gravity. Furthermore, the QNMs under the perturbation of electromagnetic field exhibit smaller real and imaginary parts than those under scalar field perturbation. By comparing the QNMs of the regular black hole featured by Minkowskian core with those of Bardeen black hole featured by de Sitter core, we find they may be an effective tool to distinguish these BHs.

gr-qc↗

arXiv2024

The shadow and observational images of the non-singular rotating black holes in loop quantum gravity

By considering the celestial light source and the thin disk source, we employ the backward ray-tracing method to carefully study the shadow, inner shadow and observational images of the non-singular rotating black holes in loop quantum gravity. The results show that the increase of quantum parameter $λ$ causes the shadow to shrink, while increases the deviation from circularity. And, the shadow's angular diameter of M87* impose stronger constraints on the observed properties of the no-singulgar rotating black holes by comparing with SgrA*. For a celestial light source, the parameter $λ$ indeed influences the distortion of light around black hole shadow, but this effect is relatively small and only becomes noticeable when extremely close to the shadow. When a thin accretion disk around black hole, it turns out that for an observer at any position, the parameter $λ$ has little effect on the shape of the inner shadow. However, it decreases the size of the inner shadow, reduces the observed light intensity, and narrows the redshifted shadow images, regardless of whether the accretion disk is prograde or retrograde. Meanwhile, it is true that the thin disk images of black hole cannot effectively reflect the internal structure of black hole. Finally, we can conclude that a key observational feature of these non-singular rotating black holes is that the larger the black hole's spin parameter, the smaller the upper limit of $λ'$s effect. And, the parameter $λ$ decreases the gravitational field's strength, thereby weakens the observed images. This could provide a possible way to constraining black hole parameters, identifying quantum gravity effects, and distinguishing loop quantum gravity black holes, even if it cannot be used to distinguish the non-singular properties of black hole.

gr-qc↗

arXiv2024

Topological classes of thermodynamics of the static multi-charge AdS black holes in gauged supergravities: novel temperature-dependent thermodynamic topological phase transition

In this paper, we investigate, in the framework of the topological approach to black hole thermodynamics, using the generalized off-shell Helmholtz free energy, the topological numbers of the static multi-charge AdS black holes in four- and five-dimensional gauged supergravities. We find that the topological number of the static-charged AdS black holes in four-dimensional Kaluza-Klein (K-K) gauged supergravity theory is $W = 0$, while that of the static-charged AdS black holes in four-dimensional gauged $-iX^0X^1$-supergravity and STU gauged supergravity theories, and five-dimensional Einstein-Maxwell-dilaton-axion (EMDA) gauged supergravity and STU gauged supergravity, and five-dimensional static-charged AdS Horowitz-Sen black hole are both $W = 1$. Furthermore, we observe a novel temperature-dependent thermodynamic topological phase transition that can happen in the four-dimensional static-charged AdS black hole in EMDA gauged supergravity theory, the four-dimensional static-charged AdS Horowitz-Sen black hole, and the five-dimensional static-charged AdS black hole in K-K gauged supergravity theory. We believe that the novel temperature-dependent thermodynamic topological phase transition could help us better understand black hole thermodynamics and, further, shed new light on the fundamental nature of gauged supergravity theories.

hep-th↗