arXiv subjects

Huajie Gong

Publications and source records attributed to Huajie Gong.

13 recordsLinked to original sources

arXiv2026

Constraining Lorentz symmetry breaking in bumblebee gravity with extreme mass-ratio inspirals

Extreme mass-ratio inspirals (EMRIs), with their long-lived and highly relativistic orbital evolution, can probe strong-field spacetime geometry and provide an important means to test general relativity. In this work, we investigate EMRI waveforms in a Schwarzschild-like black hole spacetime arising in bumblebee gravity, where Lorentz symmetry breaking (LSB) is characterized by a dimensionless parameter $\ell$. We construct EMRI waveforms within the Augmented Analytic Kludge (AAK) framework using the modified orbital frequencies and fluxes. We find that $\ell$ significantly affects the orbital evolution and thereby modifies the waveform. These modifications grow with increasing $\ell$ and are further enhanced for more eccentric orbits. Furthermore, using Bayesian analysis, we obtain the posterior distributions of EMRI with the parameter $\ell$ included. Our results show that all injected source parameters are recovered within their $1\,σ$ credible intervals. We find that the bumblebee parameter $\ell$ can be constrained with an uncertainty of order $\mathcal{O}(10^{-4})$ by LISA.

gr-qc↗

arXiv2026

Echoes and quasinormal modes for static loop quantum black bounces

We investigate scalar perturbations of the static loop quantum black bounce (LQBB) spacetime with multipole index $l=1$, focusing on time-domain signals and fundamental quasinormal frequencies (QNFs). The LQBB model provides a unified description of regular black holes (RBHs) and traversable wormholes, governed by the quantum parameter $α$ and the bounce parameter $r_b$. Using the finite difference method, we find no echoes for the displayed RBH configurations with a single-barrier effective potential, whereas clear echoes are produced by the potential well structure in selected traversable wormhole configurations. The QNFs obtained from the Prony method and the direct integration method are in good agreement. In the RBH case, increasing $r_b$ or $α$ leads to a slower decay. In the wormhole case, the QNFs depend non-monotonically on the model parameters, and the emergence of echoes is closely tied to the effective potential profile. These results show that the LQBB spacetime provides a useful framework for studying wave dynamics in RBHs and traversable wormholes, and for clarifying how horizon and throat structures affect ringdown and echoes.

gr-qc↗

arXiv2026

Gravitational waveforms from periodic orbits around a novel regular black hole

We explore potential quantum gravity signatures by studying periodic orbits and their GW emissions around a novel regular black hole (BH) featuring a Minkowski core. Using a rational number $q$, periodic orbits are classified, revealing that the deviation parameter $α_0$ reshapes the bound-orbit region while preserving characteristic ``zoom-whirl" structures. Numerical kludge waveforms reveal detectable phase shifts and amplitude modulations induced by quantum gravity effects with radiation reaction breaking orbital periodicity. Faithfulness analysis demonstrates that larger $α_{0}$ and $q$ enhance distinguishability from the Schwarzschild case, and a comparison with Hayward and quantum Oppenheimer-Snyder BHs shows their similar large-scale behaviors yield macroscopically indistinguishable orbits and waveforms.

gr-qc↗

arXiv2025

Scalar perturbation around a rotating Kalb-Ramond BTZ black hole

We investigate the scalar perturbation of a newly proposed Kalb-Ramond (KR) BTZ-like black hole. After the separation of variables for the Klein-Gordon equation, we find that the radial part reduces to the general Heun equation. Using the Heun function, we compute quasinormal modes (QNMs) subject to generic Robin boundary conditions, which shows that the KR parameter substantially modifies the QNM spectrum and only the fundamental mode on the left branch has an instability. To ascertain whether the instability is superradiant, we further analyze how the KR field changes the energy and angular momentum fluxes. Our results show that the KR parameter shifts the threshold and the range of the Robin coupling parameter where the superradiance occurs, underscoring the importance of the KR field in modeling black hole perturbations.

gr-qc↗

arXiv2025

Echoes from the Minkowski-core spacetime

In this study, we construct a class of horizonless exotic compact objects (ECOs) with Minkowski core, classifying them as either photon sphere ECOs (PS ECOs) or photon sphere lacking ECOs (PL ECOs) based on photon sphere topology. Time domain analysis reveals that the dynamical evolution can be divided into three phases: the initial ringdown, the echo phase, and the final ringdown. The echo signals exhibit the periodic damping, with quantum effects significantly accelerating the echo dissipation and prompting an earlier transition to the long lived mode dominated phase. Furthermore, the QNM spectrum of the PS ECO exhibits fundamentally different behavior from that of BHs including the presence of long lived modes and the absence of overtone outbursts providing a clear spectroscopic signature distinguishing PS ECOs from BHs. This work is significant in providing new theoretical foundations and waveform features for identifying such quantum corrected ECOs, contributing critically to the understanding of quantum gravity effects.

gr-qc↗

arXiv2025

Probing Kalb-Ramond field with extreme mass ratio inspirals

The extreme-mass-ratio inspirals (EMRIs) are emerging as precision laboratories for testing the gravity beyond general relativity. In this work, we investigate the Lorentz symmetry breaking (LSB) effect induced by the Kalb-Ramond (KR) field on the gravitational waveforms from the EMRI system. We observe that the LSB parameter $l$ appears in the leading order for the corrections of energy and angular momentum fluxes, and as $|l|$ increases, the differences in EMRI waveforms between the KR black hole and Schwarzschild black hole become more pronounced. We note that the LSB effect becomes detectable by LISA for values of $|l|\sim 10^{-6}$ with a one-year observation period. Furthermore, we use the Fisher information matrix (FIM) approach for the parameter estimation and find the detection error for $l$ can be constrained to $Δl \sim 10^{-5}$ at $\mathrm{SNR} = 20$, demonstrating the potential of space-based gravitational wave detectors to rigorously test the KR field.

gr-qc↗

arXiv2024

Quasinormal modes and ringdown waveform of the Frolov black hole

In this paper we investigate scalar perturbation over a Frolov black hole (BH), which is a regular BH induced by the quantum gravity effect. The quasinormal frequencies of a scalar field always consistently reside in the lower half-plane, and the time-domain evolution of the field demonstrates a decaying behavior, with the late-time tail exhibiting a power-law pattern. These observations collectively suggest the stability of a Frolov BH against scalar perturbation. Additionally, our study reveals that the quantum gravity effect leads to slower decay modes. For the case of the angular quantum number $l=0$, the oscillation exhibits non-monotonic behavior with the quantum gravity parameter $α_0$. However, once $l\geq 1$, the angular quantum number surpasses the influence of the quantum gravity effect.

gr-qc↗

arXiv2024

Quasinormal modes of a regular black hole with sub-Planckian curvature

This paper explores the properties of the quasinormal modes (QNMs) of a regular black hole(BH) characterized by a Minkowski core and sub-Planckian curvature. When focusing on a special case, this regular BH exhibits identical large-scale behavior with the Hayward BH and some loop quantum gravity corrected (LQG-corrected) BH. A notable characteristic of the QNMs in this regular BH is the pronounced outburst of overtones when compared to the Schwarzschild BH (SS-BH). This outburst can be attributed to the deviation from the SS-BH in the near-horizon geometry region due to the quantum gravity effect. Furthermore, we compare the QNM properties of the regular BH with those of the Hayward BH and the LQG-corrected BH. A similar phenomenon of overtone outburst is observed in the modes of the overtone. As a conclusion, the QNMs may be a powerful tool for detecting the quantum gravity effect and distinguishing different BH models.

gr-qc↗

arXiv2024

Quasinormal modes of quantum-corrected black holes

In this paper, we investigate the quasinormal mode (QNM) spectra for scalar perturbation over a quantum-corrected black hole (BH). The fundamental modes of this quantum-corrected BH exhibit two key properties. Firstly, there is a non-monotonic behavior concerning the quantum-corrected parameter for zero multipole number. Secondly, the quantum gravity effects result in slower decay modes. For higher overtones, a significant deviation becomes evident between the quasinormal frequencies (QNFs) of the quantum-corrected and Schwarzschild BHs. The intervention of quantum gravity corrections induces a significant outburst of overtones. This outburst of these overtones can be attributed to the distinctions near the event horizons between the Schwarzschild and quantum-corrected BHs. Therefore, overtones can serve as a means to probe physical phenomena or disparities in the vicinity of the event horizon.

gr-qc↗

arXiv2023

Diagnosing quantum phase transition via holographic entanglement entropy at finite temperature

We investigate the behavior of the holographic entanglement entropy (HEE) in proximity to the quantum critical points (QCPs) of the metal-insulator transition (MIT) in the Einstein-Maxwell-dilaton-axions (EMDA) model. Since both the metallic phase and the insulating phase are characterized by distinct IR geometries, we used to expect that the HEE itself characterizes the QCPs. This expectation is validated for certain cases, however, we make a noteworthy observation: for a specific scenario where $-1<γ\leq -1/3$, with $γ$ as a coupling parameter, it is not the HEE itself but rather the second-order derivative of HEE with respect to the lattice wave number that effectively characterizes quantum phase transitions (QPTs). This distinction arises due to the influence of thermal effects. These findings present novel insights into the interplay between HEE and QPTs in the context of the MIT, and have significant implications for studying QPTs at finite temperatures.

hep-th↗

arXiv2023

Charge transport properties in a novel holographic quantum phase transition model

We investigate the features of charge transport in a novel holographic quantum phase transition (QPT) model with two metallic phases: normal metallic and novel metallic. The scaling behaviors of direct current (DC) resistivity and thermal conductivity at low temperatures in both metallic phases are numerically computed. The numerical results and the analytical ones governed by the near horizon geometry agree perfectly. Then, the features of low-frequency alternating current (AC) electric conductivity are systematically investigated. A remarkable characteristic is that the normal metallic phase is a coherent system, whereas the novel metallic phase is an incoherent system with non-vanishing intrinsic conductivity. Especially, in the novel metallic phase, the incoherent behavior becomes stronger when the strength of the momentum dissipation enhances.

hep-th↗

arXiv2021

Informational properties of holographic Lifshitz field theory

In this paper, we explore the properties of holographic entanglement entropy (HEE), mutual information (MI) and entanglement of purification (EoP) in holographic Lifshitz theory. These informational quantities exhibit some universal properties of holographic dual field theory. For most configuration parameters and temperatures, these informational quantities change monotonously with the Lifshitz dynamical critical exponent $z$. However, we also observe some non-monotonic behaviors for these informational quantities in some specific spaces of configuration parameters and temperatures. A particularly interesting phenomenon is that a dome-shaped diagram emerges in the behavior of MI vs $z$, and correspondingly a trapezoid-shaped profile appears in that of EoP vs $z$. This means that for some specific configuration parameters and temperatures, the system measured in terms of MI and EoP is entangled only in a certain intermediate range of $z$.

hep-th↗

arXiv2020

Informational properties for Einstein-Maxwell-Dilaton Gravity

We study the information quantities, including the holographic entanglement entropy (HEE), mutual information (MI) and entanglement of purification (EoP), over Gubser-Rocha model. The remarkable property of this model is the zero entropy density at ground state, in term of which we expect to extract novel, even singular informational properties in zero temperature limit. Surprisedly, we do not observe any singular behavior of entanglement-related physical quantities under the zero temperature limit. Nevertheless, we find a peculiar property from Gubser-Rocha model that in low temperature region, the HEE decreases with the increase of temperature, which is contrary to that in most holographic models. We argue that this novel phenomenon is brought by the singular property of the zero temperature limit, of which the analytical verification is present. In addition, we also compare the features of the information quantities in Gubser-Rocha model with those in Reissner-Nordstrom Anti-de Sitter (RN-AdS) black hole model. It is shown that the HEE and MI of Gubser-Rocha model are always larger than those of RN-AdS model, while the EoP behaves in an opposite way. Our results indicate that MI and EoP could have different abilities in describing mixed state entanglement.

hep-th↗