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Hongbo Cheng

Publications and source records attributed to Hongbo Cheng.

At least 19 recordsLinked to original sources
arXiv2026

The indivisibility of a quantum-corrected AdS black hole with phantom global monopoles

We study the indivisibility of a quantum-corrected AdS black hole involving two kinds of global monopoles, regular or phantom ones to declare the effects from the quantum fluctuation, monopole factors and the negative cosmological constant on the evolution of black holes. We focus our attention on the possibility that this kind of black holes break into their own two parts because of the second law of thermodynamics. We derive and calculate the entropies of the initial black hole and the broken parts respectively and the entropy difference relates to the black holes structure including the quantum-gravity oscillation, global monopoles and the influence from AdS environment. It is found that the two kinds of global monopoles both keep the black holes intact instead of splitting because the entropy difference is negative. The considerable quantum fluctuation compels the defference to be positive and the fragmentation of the black holes may happen in the case that the mass of one fragmented black hole is tiny and the other one's mass is huge. The AdS radius can increase the whole value of change in entropy and the difference near the midpoint of mass ratio will become positive, so the large enough radius may lead the isolated black hole to become two parts nearly equal in the mass.

hep-th↗
arXiv2025

Probing Hernquist dark matter through the optical appearance of black holes: A comprehensive study of various accretions

The observational appearance of a black hole is critically dependent on the surrounding accreting matter, in particular on the central brightness depression and photon ring structure. We perform a systematic comparative analysis of the observational signatures of a Schwarzschild black hole embedded in a Hernquist dark matter (DM) halo under three distinct accretion scenarios: a geometrically thin disk, a static spherical flow, and an infalling spherical flow. For the thin disk model, we find that direct emission dominates the total observed intensity, while the size and brightness of the lensing and photon rings serve as sensitive probes of the Hernquist DM parameters. From a geometric perspective, the Hernquist DM halo significantly enlarges the photon sphere, resulting in an observable critical curve radius approximately $2\%$ to $30\%$ larger than in the vacuum case. Regarding the radiative signatures, the measured intensity profiles, which rely on the particular accretion models, show a general brightness suppression, which is especially affected by the Doppler de-boosting in the infalling scenario. Our results suggest that the size of the central brightness depression and the brightness profile of the black hole image provide a valuable theoretical framework for constraining the distribution of dark matter in galactic centers.

astro-ph.HE↗
arXiv2025

The Barrow entropies in the thermodynamics of high-dimensional Gauss-Bonnet black holes

We study the thermodynamics of $D$-dimensional Gauss-Bonnet black holes with Barrow entropy. It is found that the Gauss-Bonnet coupling and the Barrow factor revise the thermodynamic variables such as event horizon, Hawking temperature, entropy and heat capacity. It is interesting that the larger five-dimensional black holes exist stably and the smaller ones evaporate to disappear owing to the nature of heat capacities amended by the coupling and factor. The discussions exhibit that the $D$-dimensional black holes with $D=6, 7$ set free all of their energy to vanish because of the minus heat capacities as functions of Hawking temperature although the extra term and the fractal power bring about their revisions on the functions, but they cannot change the heat capacity signs, so they also cannot change the fate of six- or seven-dimensional black holes.

gr-qc↗
arXiv2025

The accretion disk and neutrino propagation of Barrow-modified Black Hole

This paper attempts to clarify the deep consequences of Barrow fractal black hole spacetime configurations caused by quantum gravity on neutrino pair annihilation and accretion disk dynamics. We systematically derive the analytical expression for the innermost stable circular orbit (ISCO) radius ($r_{\text{ISCO}}\propto M^{2/(2+\Delta)}$) by building a Barrow-modified static spherically symmetric metric ($r\rightarrow r^{1+\Delta/2}$), and we find that increasing $\Delta$ significantly shifts the ISCO inward. We numerically solve the radiation flux, effective temperature, and differential luminosity distribution under the modified metric based on the Novikov-Thorne relativistic thin accretion disk model. For $\Delta=1$, the results show that the temperature increases by $62.5\%$, the peak disk radiation flux increases by $22.5\%$, and the spectral radiance increases by around $50\%$. Fractal horizons enhance neutrino trajectory bending effects, according to further study of neutrino pair annihilation ($\nu\bar{\nu}\rightarrow e^+e^-$) energy deposition processes using local Lorentz transformations and null geodesic equations. The energy deposition rate for $\Delta=1$ is $8-28$ times higher than classical estimates when the black hole radius is $R/M\sim3-4$. This work provides important theoretical insights into the influence of quantum spacetime geometry on high-energy astrophysical phenomena in extreme gravitational fields by establishing, for the first time, quantitative relationships between the Barrow parameter $\Delta$ and neutrino pair annihilation energy and accretion disk radiative efficiency.

gr-qc↗
arXiv2025

The validity of the universal relation between corrections to entropy and the extremality of Schwarzschild-de Sitter black holes under the GUP and EUP

We investigate the extremality relations by examining perturbative corrections to both the entropy of Schwarzschild-de Sitter black holes and their extremality bounds under the Nariai limit within the frame of the generalized uncertainty principle (GUP) and the extended uncertainty principle (EUP) respectively. The GUP-corrected or EUP-corrected horizons bring about the additional terms finally in the Goon-Penco relation to violate the universal ones and these extra terms cannot be canceled by adding the adequate conditions. We argue that the corrected uncertainty principles including GUP and EUP violate the validity of extremality relations because no matching condition can be imposed to support the Goon-Penco relation unless the influences from GUP and EUP disappear.

hep-th↗
arXiv2025

The thermodynamic stability and phase structure of the Einstein-Euler-Heisenberg-AdS black holes

In both canonical ensemble and grand canonical ensemble, the thermodynamic stability and phase structure of Einstein-Euler-Heisenberg-AdS black hole are studied. We derive the Hawking temperature, Helmholtz free energy, Gibbs potential, entropy and heat capacity of the black holes. We compute the minimum temperature to find that the phase transition may happen at the lowest point. The entropy-temperature diagram consists of two parts. The upper part belonging to the large black holes under the influence from the electromagnetic self-interactions keeps the positive heat capacity, leading the huge compact objects to survive. The lower curves corresponding to the small ones show that the heat capacity of the tiny black holes is negative, which means that the nonlinear-effect-corrected smaller sources will evaporate. The further discussions show that the nonlinear effect modifies the thermodynamic quantities, but the corrections limited by the nonlinear factor $\mu$ with allowed values can not change the properties and the phase structure fundamentally and thoroughly. We argue that the influence from self-interaction can not make the Einstein-Euler-Heisenberg-AdS black holes to split under the second law of thermodynamics.

hep-th↗
arXiv2024

The neutrino flavor oscillations in the static and spherically symmetric black-hole-like wormholes

We study the effects of neutrino lensing induced by a Damour-Solodukhin wormhole on the neutrino oscillation. We derive and calculate the flavour transition probabilities in the presence of Damour-Solodukhin factor $\Lambda$ as a shift in the massive source to show that the neutrino flavour oscillation is also sensitive not only to the sign of difference between the squared masses but also to the individual mass of neutrinos in both the two-flavour and the three-flavour cases, which is similar to the results for the black holes in the previous works mentioned here. As a consequence of parameter $\Lambda$ within a region, a series of curves of probability function versus the azimuthal angle $\phi$ with definite masses of neutrino can be plotted and their shapes resemble each other in the case of two-flavoured neutrinos and of three-flavoured ones. In view of the probability functions due to the wormhole, we reveal that the contribution of the factor $\Lambda$ is novel. Based on our analytical and numerical discussions on the probability expressions, the difference of the neutrino flavour oscillation arising from the shift in the wormhole factor $\Lambda$ is detectable. It is crucial that the $\Lambda$ as deviation from the black holes can change the shapes of the curves greatly, in the case of three-flavoured neutrinos in particular. The detailed comparisons can be made among our estimations depicted in the figures for neutrino oscillations and the measurements from the detector, which open a new window for judging whether the remote star as lens is black-hole-like wormhole or just a spherically symmetric black hole and further the wormhole factor $\Lambda$ can be estimated.

gr-qc↗
arXiv2023

The gamma-ray burst arising from neutrino pair annihilation in the static and spherically symmetric black-hole-like wormholes

We look into the neutrino-antineutrino pair ($\nu+\bar{\nu}\longrightarrow e^{-}+e^{+}$) annihilation in the Damour-Solodukhin wormhole spacetime whose metric component involves a shift in contrast to the similar black hole. The deep analysis of the surface temperature of the accretion disk of static, spherically symmetric black-hole-like wormholes from R. Kh. Karimov et.al. reveals that the accretion disks of the wormholes are hotter than that of comparable black holes, indicating that the wormholes accretion disk can release neutrinos. Further we investigate the energy deposition rate from the neutrino pair annihilation around the Damour-Solodukhin wormhole thought as a mimicker of Schwarzschild black hole. By comparison made between the black-hole-like wormhole and the similar black hole, we demonstrate that the wormhole's accretion disk drawing the annihilation can become a source of gamma-ray burst although the more significant deviation from the similar black hole reduces the emitted power slightly. The ratio of energy deposition per unit time from the annihilation surrounding the accretion disk of the Damour-Solodukhin wormhole over the emitting power of black hole might alter noticeably depending on how slightly the metrics of the wormhole differ from the black hole spacetime.

hep-th↗
arXiv2023

The shadow and gamma-ray bursts of a Schwarzschild black hole in asymptotic safety

We research on the neutrino pair annihilation $\nu+\overline{\nu}\longrightarrow e^{-}+e^{+}$ around a massive source in asymptotic safety. Since neutrinos and photons have the same geodesic equation around black holes, we can estimate the radius where the neutrinos will be released by obtaining a series of trajectory curves with various correction values $\xi$. The black hole shadow radius is influenced by the correction parameter $\xi$. The black hole shadow radius decreases with increasing the $\xi$. The ratio $\dfrac{\dot{Q}}{\dot{Q}_{Newt}}$ corresponding to the energy deposition per unit time over that in the Newtonian case is derived and calculated. We find that the quantum corrections to the black hole spacetime affect the emitted energy rate ratio for the annihilation. It is interesting that the more considerable quantum effect reduces the ratio value slightly. Although the energy conversion is damped because of the quantum correction, the energy deposition rate is enough during the neutrino-antineutrino annihilation. The corrected annihilation process can become a source of gamma ray burst. We also investigate the derivative $\dfrac{\mathrm{d}\dot{Q}}{\mathrm{d}r}$ relating to the star's radius $r$ to show that the quantum effect for the black hole will drop the ratio. The more manifest quantum gravity influence leads the weaker neutrino pair annihilation.

gr-qc↗
arXiv2022

The Horava-Lifshitz Modifications of the Casimir effect at finite temperature revisted

We proceed with the study of the Casimir force for parallel plates at finite temperature in the Horava-Lifshitz (HL) theory. We find that the HL exponent can not be chosen as an integer, or the Casimir energy will be a constant and further the Casimir force between two parallel plates will vanish. The higher temperature makes the attractive Casimir force weaker, which is consistent with the original consequence confirmed theoretically and experimentally. We can select the HL factor adequately to lead the thermally revised Casimir force to be similar to the standard results for the parallel plates.

hep-th↗
arXiv2022

The neutrino pair annihilation ($\nu\bar{\nu}\longrightarrow e^{-}e^{+}$)around a massive source with an $f(R)$ global monopole

In this work we investigate the neutrino pair annihilation around a gravitational object involving an $f(R)$ global monopole. We derive and calculate the ratio $\frac{\dot{Q}}{\dot{Q_{Newt}}}$ meaning that the energy deposition per unit time is over that in the Newtonian case. It is found that the more deviation from general relativity leads more energy to set free from the annihilation with greater ratio value. It should also be pointed out that the existence of global monopole makes a sharp increase in the ratio $\frac{\dot{Q}}{\dot{Q_{Newt}}}$, causing heavier gamma-ray burst. We also discuss the derivative $\frac{d\dot{Q}}{dr}$ as a function of radius $r$ of star to show the similar characters that the considerable modification of Einstein's gravity and the global monopole with unified theory order will raise the amount of $\frac{d\dot{Q}}{dr}$ greatly. The stellar body with $f(R)$ global monopole can be well qualified as a source of gamma-ray bursts. Moreover, we can select the factor $\psi_{0}$ to be comparable with the accelerating universe while regulate the parameter $\eta$ for the global monopole in order to make the ratio curves to coincide with the results from astronomy. It is possible to probe the monopole from astrophysical observations.

gr-qc↗
arXiv2019

The instability of a black hole with $f(R)$ global monopole under extended uncertainty principle

We consider the evolution of black hole involving an $f(R)$ global monopole based on the Extended Uncertainty Principle (EUP). The black hole evolutions refer to the instability due to the Parikh-Kraus-Wilczeck tunneling radiation or fragmentation. It is found that the EUP corrections make the entropy difference larger to encourage the black hole to radiate more greatly. We also show that the appearance of the EUP effects result in the black hole's division. The influence from global monopole and the revision of general relativity can also adjust the black hole evolution simultaneously, but can not change the final result that the black hole will not be stable because of the EUP's effects.

hep-th↗
arXiv2018

The further estimations of the Q-balls with one-loop motivated effective potential

The analytical estimations on the Friedberg-Lee-Sirlin typed Q-balls is performed. The two-field Q-balls are also discussed under the one-loop motivated effective potential subject to the temperature. We argue under the analytical consideration that the parameters from the potential can be regulated to lead the energy per unit charge of Q-balls to be lower to keep the model stable. If the energy density is low enough, the Q-balls can become candidates of dark matter. It is also shown rigorously that the two-field Q-balls can generate in the first-order phase transition and survive while they are affected by the expansion of the universe. The analytical evaluations show that the Q-balls with one-loop motivated effective potential can exist with the adjustment of coefficients of terms. We cancel the infinity in the energy to obtain the necessary conditions consist with those imposed in the previous work. According to the approximate expressions instead of curves versus the model parameters with a series of fixed values, the lower temperature will reduce the energy density, so there probably have been more and more stable Friedberg-Lee-Sirlin typed Q-balls to become the dark matter in the expansion of the universe.

hep-th↗
arXiv2017

The further analytical discussions on the $U(1)$ gauged Q-balls with $N$-power potential

We discuss the $U(1)$ gauged Q-balls with $N$-power potential to examine their properties analytically. More numerical descriptions and some analytical consideration have been contributed to the models governed by four-power potential. We also demonstrate strictly some new limitations that the stable $U(1)$ gauged Q-balls should accept instead of estimating those with only some specific values of model variables numerically. Having derived the explicit expressions of radius, the Noether charge and energy of the gauged Q-balls, we find that these models under the potential of matter field with general power and the boundary conditions will exist instead of dispersing and decaying. The Noether charge of the large gauged Q-balls must be limited. The mass parameter of the model can not be tiny.

hep-th↗
arXiv2017

The fragmentation instability of a black hole with $f(R)$ global monopole under GUP

The fragmentation of black hole containing $f(R)$ global monopole under GUP is studied. We focus on that the black hole breaks into two parts. We derive the entropies of the initial black hole and the broken parts while the generalization of Heisenberg's uncertainty principle is introduced. We find that the $f(R)$ global monopole black hole keeps stable instead of breaking because the entropy difference is negative without the generalization. The fragmentation of the black hole will happen if the black hole entropies are limited by the GUP and the considerable deviation from the general relativity leads the case that the mass of one fragmented black hole is extremely small and the other one is extremely large.

hep-th↗
arXiv2016

The tunneling radiation of a black hole with a $f(R)$ global monopole under generalized uncertainty principle

The Parikh-Kraus-Wilczeck tunneling radiation of black hole involving a $f(R)$ global monopole is considered based on the generalized uncertainty principle. The influences from global monopole, $f(R)$ gravity and the corrections to the uncertainty appear in the expression of black hole entropy difference. It is found that the global monopole and the revision of general relativity both hinder the black hole from emitting the photons. The two parts as corrections to the uncertainty make the entropy difference of this kind of black hole larger or smaller respectively.

hep-th↗
arXiv2015

The Casimir effect at finite temperature in a six-dimensional vortex scenario

The Casimir effect for parallel plates satisfying the Dirichlet boundary condition in the context of effective QED coming from a six-dimensional Nielsen-Olesen vortex solution of the Abelian Higgs model with fermions coupled to gravity is studied at finite temperature. We find that the sign of the Casimir energy remains negative under the thermal influence. It is also shown that the Casimir force between plates will be weaker in the higher-temperature surroundings while keeps attractive. This Casimir effect involving the thermal influence is still inconsistent with the known experiments. We find that the thermal correction can not compensate or even reduce the modification from this kind of vortex model to make the Casimir force to be in less conflict with the measurements.

hep-th↗