arXiv subjects

Xian-Ru Hu

Publications and source records attributed to Xian-Ru Hu.

At least 19 recordsLinked to original sources

arXiv2025

Quasinormal modes and greybody factor of charged black hole in non-commutative geometry

In this article, the quasinormal modes and greybody factor of charged black hole in non-commutative geometry are studied. Under the assumption of a uniformly distributed charge within the matter, we obtain the metric for a charged black hole in non-commutative geometry. We calculated the wave function and obtained the effective potential of three different perturbed fields with spin. Then we applied $6^{\rm{th}}$ order WKB method to analyze the quasinormal modes of the black hole and derived quasinormal frequencies. Futhermore, we discussed the greybody factor in different perturbed fields under this spacetime.

gr-qc↗

arXiv2025

Thermodynamic phase transition and Joule-Thomson expansion of a quantum corrected black hole in AdS spacetime

The thermodynamics in the extended phase space of a quantum corrected black hole (BH) proposed recently is presented in this work. Our study shows that the phase transition behavior of the BH is analogous to that of conventional Schwarzschild BH in anti-de Sitter (AdS) space; however, a critical temperature exists such that when the BH temperature exceeds this critical value, the small BH phase and the large BH phase become separated, and no phase transition occurs. Due to the introduction of the quantum parameter $ξ$, the BH equation of state splits into two branches. One branch reduces to the Schwarzschild-AdS case as $ξ\to0$, with its phase transition pressure lower than the critical pressure; another branch's phase transition pressure is greater than the critical pressure. The study shows that the $T-r_{+}$ phase transition and heat capacity are similar to those of the Schwarzschild-AdS BH. The Joule-Thomson expansion is divided into two stages: in the earlier stage, the BH pressure increases until it reaches a maximum; in the later stage, the pressure gradually decreases. In each stage, the BH may undergo an inversion point, resulting in the inversion curve with two branches. In addition, each stage has a minimum inversion mass, below which any BH (in each respective stage) has no inversion point.

gr-qc↗

arXiv2025

Estimating the strength of Lorentzian distribution in non-commutative geometry by solar system tests

In this paper, we study four classical tests of Schwarzschild space-time with Lorentzian distribution in non-commutative geometry. We performed detailed calculations of the first-order corrections induced by the non-commutative parameter on planetary orbital precession, light deflection, radar wave delay, and gravitational redshift. The study showed that the impact of the non-commutative parameter on the time-like geodesics is significantly greater than its effect on the null geodesics. By using a series of precise experimental observations, the allowable range for the non-commutative parameter is ultimately constrained within $Θ\leq0.067579~\mathrm{m}^{2}$, which is given by Mercury's orbital precession. This result aligns with the view that $\sqrtΘ$ is of the order of the Planck length. Moreover, this constrained parameter range exceeds the Planck scale by a significant margin.

gr-qc↗

arXiv2025

Thermodynamic properties and Joule-Thomson expansion of AdS black hole with Gaussian distribution in non-commutative geometry

The thermodynamics and Joule-Thomson expansion of anti-de Sitter black hole (AdS BH) with Gaussian distribution in non-commutative geometry is systematically studied. The metric of Gaussian-distributed BH is obtained, showing a dS geometry at the core of BH. The research indicates that the BH characterized by a Gaussian distribution exhibit thermodynamic properties that are remarkably similar to those of BH with a Lorentzian distribution in non-commutative geometry. This similarity is specifically manifested in the small BH-large BH phase transition, the corrected first law of thermodynamics, the criticality, the heat capacity, the zeroth-order phase transition and the Joule-Thomson process. Notably, the critical ratio of Gaussian-distributed BH (0.46531) is significantly larger than those observed in Van der Waals fluids (0.375), and indeed, it is also substantially exceed those of Lorentzian-distributed BH (0.36671). Moreover, compared to the case of Lorentzian source, the zeroth-order phase transition effect in Gaussian-distributed BH is exceedingly subtle (accompanied by a relative increase in the Gibbs free energy on the order of $10^{-3}\!\sim\!\!10^{-2}$) and is difficult to detect distinctly.

gr-qc↗

arXiv2025

Thermodynamics of Schwarzschild-AdS black hole in non-commutative geometry

In this paper, we study the thermodynamics of Schwarzschild-anti-de Sitter black holes within the framework of non-commutative geometry. By solving the Einstein's equations, we derive the corrected Schwarzschild-AdS black hole with Lorentzian distribution and analyze the thermodynamics. Our results confirm that if the energy-momentum tensor outside the event horizon is related to the mass of the black hole, the conventional first law of thermodynamics will be violated. The study of criticality reveals that the black hole undergoes a small black hole-large black hole phase transition similar to that of the Van der Waals system, with a critical point and a critical ratio slightly smaller than that of the Van der Waals fluid. As the non-commutative parameter increases, the phase transition process shortens, leading to a critical point, and ultimately to the disappearance of the phase transition. The violation of the conventional first law results in a discontinuity of the Gibbs free energy during the phase transition, indicating the occurrence of zeroth-order phase transition. Moreover, we investigate the Joule-Thomson expansion, obtaining the minimum inversion temperature and the minimum inversion mass.

gr-qc↗

arXiv2024

Thermodynamics of AdS-Schwarzschild-like black hole in loop quantum gravity

We obtained the metric of the Schwarzschild-like black hole with loop quantum gravity (LQG) corrections in anti-de Sitter (AdS) space-time, under the assumption that the cosmological constant is decoupled in LQG. We investigated its thermodynamics, including the equation of state, criticality, heat capacity, and Gibbs free energy. The $P-v$ graph was plotted, and the critical behavior was calculated. It was found that, due to the LQG effect, the quantum-corrected Schwarzschild-AdS black hole exhibits a critical point and a critical ratio of $7/18$, which differs from the Reissner-Nordstr$\ddot{\mathrm{o}}$m-AdS black hole's ratio of $3/8$ (the same as that of the Van der Waals system) slightly. However, there are still some similarities compared to the Van der Waals system, such as the same critical exponents and a similar $P-v$ graph. Moreover, it is concluded that the energy-momentum tensor related to the black hole's mass could violate the conventional first law of thermodynamics. This modified first law may violate the conservation of Gibbs free energy during the small black hole-large black hole phase transitions, potentially indicating the occurrence of the zeroth-order phase transition. The Joule-Thomson expansion was also studied. Interestingly, compared to the Schwarzschild-AdS black hole, the LQG effect leads to inversion points. The inversion curve divides the $\left(P,T\right)$ coordinate system into two regions: a heating region and a cooling region, as shown in detail by the inversion curves and isenthalpic curves. The results indicated that there is a minimum inversion mass, below which any black hole will not possess an inversion point.

gr-qc↗

arXiv2024

A Study of Decay Rate of Bound Negative Muons

A number of experiments show that the decay lifetimes of muons bound to atomic nuclei are longer than the decay lifetimes of free muons. In this paper, a scheme of extending quantum mechanics (EQM) is proposed to resolve this problem. The Schr$\ddot{\text{o}}$dinger's equation is obtained to prove the validation of this attempt. The decay ratio of bound muons is also calculated in EQM, and the result is in good agreement with the experimental data.

hep-ph↗

arXiv2024

Thermal chaos of quantum-corrected-AdS black hole in the extended phase space

We briefly analyzed the equation of state and critical points of the quantum-corrected Schwarzschild-like black hole and used the Melnikov method to study its thermal chaotic behavior in the extended phase space of flat, closed, and open universes. The results show that the black hole's thermodynamic behavior is similar to that of the Van der Waals system. Although the critical ratios at the critical points differ among the three universes, they are all independent of the quantum correction parameter. For chaos, time perturbations will lead to chaotic behavior when their amplitude exceeds a critical value that depends on the quantum correction parameter and the radius of the dust sphere in the FRW model. Based on this, we found that the chaotic behavior of the black hole varies across different universes depending on the quantum correction parameter, but this parameter always makes chaos more likely. Using the value of the quantum correction parameter determined by Meissner, chaos is always more difficult to occur in an open universe compared to the other two types of universes. Which universe is most prone to chaos depends on the radius of the dust sphere. Finally, chaotic behavior is always present under spatial perturbations.

gr-qc↗

arXiv2024

Euler-Heisenberg black hole surrounded by perfect fluid dark matter

A generation method of new metric in the case of static spherically symmetric space-time is derived. Using this approach, we construct a metric which describes Euler-Heisenberg black hole surrounded by perfect fluid dark matter and investigate its optical and thermodynamic properties. We found that radius of shadow will increase with the increase of dark matter effect, and more strong dark matter will diminish the light intensity of accretion disk generally. Moreover, in thermodynamics, when quantum electrodynamic parameter is positive, there will be a critical value of dark matter parameter, which determine the number of black hole's critical points.

gr-qc↗

arXiv2024

Decoding quantum gravity information with black hole accretion disk

The combination of Loop Quantum Gravity theory with the classical gravitational collapse model has effectively addressed the singularity problem of black holes and predicted the emergence of white holes in the late stages of collapse. The quantum extension of Kruskal spacetime suggests that the appearance of white holes may carry information from companion black holes in the universe earlier than ours. Photons emitted from the accretion disk of companion black holes will enter the companion black hole, traverse through quantum regions from the white hole to our universe, and produce imaging of accretion disk carrying quantum gravity information. In our work, we have obtained the accretion disk images of black hole from a universe earlier than ours, transported by a white hole within our universe, along with the positions and widths of these images exactly. Remarkably, behaviours of white hole and black hole imaging are similar in photon sphere and contrary to some cases of outside. This will provide valuable references for astronomical observations to validate quantum gravity theory.

gr-qc↗

arXiv2024

Optical properties of Euler-Heisenberg black hole in the Cold Dark Matter Halo

The optical properties of Euler-Heisenberg (EH) black hole (BH) surrounded by Cold Dark Matter (CDM) halo are investigated. By changing BH's parameters, we found that the radius of horizon r_{h} and radius of photon sphere r_{ph} will transparently increase as CDM halo parameters R and ρincrease. To show the influence of CDM halo on the BH's optical characteristics, we took two sets of R and ρwith prominent differences and plot the first four orders of images for thin accretion disk with different angle of inclination θof observer. The images with light intensity distributions using Novikov-Thorne (N-T) model are also derived, as well as the effective potential, photon orbits. Especially, analysis of intersection behaviors between photon trajectories with different impact parameters and circular time-like orbits in accretion disk will help better understand the image of thin accretion disk. Our results showed that CDM halo will make BH become more larger and dimmer distinctly.

gr-qc↗

arXiv2023

Shadow of Schwarzschild Black Hole in the Cold Dark Matter Halo

The Schwarzschild black hole in the Cold Dark Matter (CDM) halo is studied, and the radiation laws of the thin accretion disk near the black hole are discussed and summarized. The orbits of light around the black hole are also calculated. Additionally, using the Novikov-Thorne model's light intensity function of the thin accretion disk, it is possible to solve for the shadow created by the thin accretion disk near the Schwarzschild black hole as well as the observed luminosity of the disk.

gr-qc↗

arXiv2022

Double shadow of a 4D Einstein-Gauss-Bonnet black hole and their connection between with quasinormal modes

In this paper, we study the shadow of a 4D Einstein-Gauss-Bonnet black hole as photons couple to the Weyl tensor and find that the propagation of light depends on its polarization which leads to the existence of a double shadow. Then, we discuss the effect of the coupling parameter $λ$, the polarization of light and the Gauss-Bonnet coupling constant $α$ on shadow. Further we explore the influence of the Gauss-Bonnet coupling constant $α$ on the quasinormal modes (QNMs) of massless scalar field and investigate the connection between the real part of QNMs in the eikonal limit and the shadow radius of black holes. We find that in the eikonal limit the real part of QNMs is inversely proportional to the shadow radius under the case of the photons uncoupled to the Weyl tensor.

gr-qc↗

arXiv2021

Bardeen black hole in magnetically charged four-dimensional Einstein-Gauss-Bonnet gravity

In this paper, we investigate the shadow radius and quasinormal modes of a four-dimensional magnetically charged Einstein-Gauss-Bonnet Bardeen black hole and point out a simple connection between them in the eikonal limit. By studying a massless scalar field perturbation in this spacetime background and using the sixth-order Wentzel-Kramers-Brillouin(WKB) approximation, we get the quasinormal modes(QNMs) and perform a detailed analysis. It shows that the quasinormal modes are depend on the Gauss-Bonnet coupling constant and the magnetic charge. We also give a formula of the QNMs and shadow radius in the eikonal limit and check it numerically for the real and imaginary part of it, respectively.

gr-qc↗

arXiv2021

Coexistence of Type-II and Type-IV Dirac Fermions in SrAgBi

Relativistic massless Weyl and Dirac fermions have isotropic and linear dispersion relations to maintain Poincaré symmetry, which is the most basic symmetry in high-energy physics. The situation in condensed matter physics is less constrained; only certain subgroups of Poincaré symmetry -- the 230 space groups that exist in 3D lattices -- need be respected. Then, the free fermionic excitations that have no high energy analogues could exist in solid state systems. Here, We discovered a type of nonlinear Dirac fermion without high-energy analogue in SrAgBi and named it type-IV Dirac fermion. The type-IV Dirac fermion has a nonlinear dispersion relationship and is similar to the type-II Dirac fermion, which has electron pocket and hole pocket. The effective model for the type-IV Dirac fermion is also found. It is worth pointing out that there is a type-II Dirac fermion near this new Dirac fermion. So we used two models to describe the coexistence of these two Dirac fermions. Topological surface states of these two Dirac points are also calculated. We envision that our findings will stimulate researchers to study novel physics of type-IV Dirac fermions, as well as the interplay of type-II and type-IV Dirac fermions.

cond-mat.mtrl-sci↗

arXiv2021

Insight into the Microscopic Structure of an AdS Black Hole from the Quantization

We explore the possible microscopic structure of a charged AdS black hole from the quantized viewpoint. A further study shows that some black holes cannot absorb "energy quantum" under certain conditions from the view of quantization. By the quantization of the black hole horizon area, we show the relation between the number of quanta of area and the microscopic degrees of freedom of the black hole. We also interpret a latent heat of thermodynamical phase transition as a transition between the number of quanta of area of large black hole(LBH) and the number of quanta of area of small black hole(SBH) in the charged AdS black hole. Furthermore, the Ruppeiner scalar curvature connecting with the number of quanta of area is also shown.

hep-th↗

arXiv2021

Shadow of topologically charged rotating braneworld black hole

In this paper, we discuss optical properties of the topologically charged rotating black hole. We study the horizon, the photon region, the shadow of the black hole and other observables. The results show that in addition to the black hole spin parameter $a$, the other two parameters, tidal charge $β$ and electric charge $q$, are also found to affect the horizon, the photon region and the black hole shadow. In a certain range, with the increase of the three parameters, the horizon distance, shape of the photon region and the black hole shadow will all shrink. Moreover, with the increase of these three parameters, the distortion parameter $δ_{s}$ gradually increases, while the peak of the black hole energy emission rate decreases.

gr-qc↗

arXiv2019

The Varying Speed of Light in Eddington-inspired Born-Infield Gravity with Rainbow Metric

In this paper, we proposed that at each point of spacetime, in addition to the Riemannian metric tensor which describes the geometry of spacetime and the gravitational field, there is an rainbow metric tensor which shows the geometry of spacetime depends on the energy of the test particle. Because Eddington-inspired Born-Infield(EiBI) gravity can be seen as a special bi-metric gravity, we research a varying speed of light theory for a bi-metric gravity corresponding to EiBI gravity. For FRW universe, we find the energy of test particle will increase with rising energy density of universe. We also research the varying speed of light for three different kinds of rainbow functions and find the sign of parameter $κ$ would influence the trend of spend of light.

gr-qc↗