arXiv subjects

Telem Ibungochouba Singh

Publications and source records attributed to Telem Ibungochouba Singh.

11 recordsLinked to original sources

arXiv2026

Geodesic structure, eikonal quasinormal modes and thermodynamic properties of a Schwarzschild-de Sitter-like black hole with global monopole in Bumblebee gravity

We investigate the geodesic dynamics, eikonal quasinormal modes (QNMs), and extended phase space thermodynamics of a Schwarzschild-de Sitter-like black hole coupled with a global monopole in Bumblebee gravity. Our analysis reveals that spontaneous Lorentz symmetry breaking and topological defects modify the effective radial dynamics, leading to lower effective potential barriers and a reduced magnitude of the effective force. For null geodesics, higher monopole parameters expand the photon sphere and critical impact parameter, implying an enlarged black hole shadow, while mitigating dynamical instability. For massive particles, the stable circular orbit window narrows significantly as the Outermost Stable Circular Orbit (OSCO) shrinks, alongside a marked enhancement in perihelion precession. In addition, we examine the correspondence between the eikonal QNMs and the properties of null geodesics. The excellent agreement between the eikonal approximation and the WKB method for scalar and electromagnetic perturbations supports the validity of the correspondence for the spacetime under consideration. In the extended thermodynamic phase space, we evaluate the black hole as a holographic heat engine. We demonstrate that classical efficiency is mathematically blind to Lorentz violation; however, introducing a quantum-corrected modified entropy tightly couples the macroscopic work output to the symmetry-breaking framework. Ultimately, the necessity to respect the Carnot bound imposes a strict macroscopic constraint on the Lorentz-violating parameter, safeguarding the Second Law of Thermodynamics.

gr-qc↗

arXiv2026

Multi-Spin Perturbations, Thermodynamics, and Observational Signatures of Reissner-Nordstrom Black Holes in Bumblebee Gravity

In this paper, we present a comprehensive investigation into the dynamical and thermodynamic properties of the charged Reissner-Nordström (RN) black hole (BH) in the bumblebee gravity framework, where spontaneous Lorentz symmetry breaking (LSB) occurs. To analyze the dynamical behavior, we apply the unified Teukolsky master equation within the Newman-Penrose formalism to evaluate massless field perturbations of arbitrary spins ($s=0, 1/2, 1, 3/2, 2$). By deriving the corresponding effective potentials, we compute the quasinormal modes (QNMs) frequencies using the Padé-improved 6th-order WKB approximation and the Asymptotic Iteration Method (AIM) and evaluate the greybody factors for all perturbing fields, demonstrating how the LSB parameter $L$ and the BH charge $Q$ modify the spacetime's damped oscillations and wave propagation. We further assess the observational prospects of these QNMs by determining the black-hole mass ranges accessible to current and future gravitational-wave detectors, including LISA, Virgo, and LIGO. Moreover, we investigate the modified thermodynamic structure, calculating the Hawking temperature, entropy with logarithmic thermal corrections and heat capacity. Our thermodynamic analysis reveals a second-order phase transition whose critical radius is heavily governed by the background charge. These combined findings provide valuable theoretical insights into how Lorentz violation affects the physical stability, thermal evolution, and phase structure of charged BHs.

gr-qc↗

arXiv2026

Strong Lensing and Quasinormal modes of black hole around global monopole

In this paper, we investigate various key aspects of a static and spherically symmetric black hole with global monopole. Firstly, we analyze the deflection angle in the strong field limit of massive particle by the global monopole. It shows that the angle of deflection increases when the two characteristic parameters for monopole configuration increase. The influence of the global monopole parameter on the lensing observables and the black hole shadow are studied. This shows that larger monopole parameter corresponds to larger shadow radii. The dynamics of timelike geodesics is also investigated in the spacetime. General circular orbits and the innermost stable circular orbits (ISCO) of timelike particles are discussed, highlighting that the monopole parameter significantly affects the circular orbits and the ISCO. In particular, it is observed that the radius of ISCO rises monotonically with $η$. In addition, the Lyapunov exponent is used to analyze the stability of timelike geodesics. The quasinormal modes for electromagnetic perturbation of the black hole with varying $η$ is also investigated. Our findings indicate that increasing the monopole parameter gives rise to gravitational waves with slower damping oscillations. To further validate the derived quasinormal mode spectrum, we discuss the evolution of electromagnetic perturbations in the time domain profile, confirming the presence of the characteristic quasinormal ringing followed by late-time power-law tails.

gr-qc↗

arXiv2026

Thermodynamics and null-geodesic of the Kerr-Newman black hole surrounded by quintessence and a cloud of string

In this paper, we study the effect of the modified dispersion relation (MDR) on the thermodynamics of the Kerr-Newman black hole surrounded by quintessence and a cloud of string. The thermodynamic properties of the Kerr-Newman black hole are shown to rely not only on the black hole's properties but also on the parameters associated with the modified dispersion relation, quintessence, and the cloud string. Additionally, the equation of state is impacted by these parameters. The remnant and the stability of the black hole are also discussed under the correction of MDR, quintessence, and a cloud of string. In addition, the null geodesic structure of the spacetime is studied using the Hamilton--Jacobi formalism. The effective potential for photon motion is obtained, and the radii of the prograde and retrograde circular photon orbits are determined. The instability of these circular photon orbits is further characterized by the Lyapunov exponent.

gr-qc↗

arXiv2026

Kerr-Newman black hole surrounded by quintessence under quantum gravity effects and gravity's rainbow

In this paper, we investigate the quantum gravity effects on the tunneling of particles and gravity's rainbow across the event horizon of Kerr-Newman black hole (KNBH) surrounded by the quintessence. The aspect of quantum gravity has been introduced by applying the Generalized Uncertainty Principle (GUP) to the Klein-Gordon equation and the Dirac equation of scalar and fermion particles. By solving the Generalized Klein-Gordon and Dirac equations obeyed by scalar and fermion particles, corrections to the Hawking temperature of the KNBH in the presence of quintessence is discussed. The tunneling of fermions is also examined using the modified Hamilton-Jacobi equation also known as modified Rarita-Schwinger equation, and the corrected Hawking temperature is determined. The corrected Hawking temperature of the KNBH surrounded by quintessence is found to be dependent not only on the properties of the black hole but also on the quantum numbers of the emitted particles and quintessence. Then, we explored the KNBH surrounded by quintessence within the framework of gravity rainbow using rainbow functions. In the context of rainbow functions in loop quantum gravity, we derive the Hawking temperature, heat capacity, equation of state parameters, and entropy for the KNBH surrounded by quintessence. It is found that these quantities are influenced by both the quintessence and the rainbow gravity.

gr-qc↗

arXiv2025

Strong lensing and Hawking spectra of charged black hole under Lorentz violation theory

In this paper, we investigate the strong gravitational lensing effects around the Reissner-Nordstr{ö}m-like black hole (RN-like BH) in bumblebee gravity. We calculate the lensing quantities such as deflection angle, radius of the photon sphere, angular separation, relativistic image characteristics, Einstein ring and time delay. By taking the supermassive black holes (SMBHs) like Sgr A*, M87*, NGC 1332, NGC 4649 etc. as RN-like BH, we compute the lensing observables and compare with the observables associated with the Reissner-Nordström black hole (RNBH). The quasinormal modes (QNMs) of massless Dirac field perturbation of Reissner-Nordstr{ö}m-de Sitter-like (RNdS-like) BH are also calculated. We discuss the behaviour of both real and imaginary parts of QNM frequencies with varying of $Q$ and $L$. It shows the damping rate and the oscillation frequency decrease with increasing $L$ but it has the opposite effect for the increase of $Q$. We further explore the detectability of QNMs by LIGO and LISA, and study the impact of $L$ and $Q$ on the detectable BH mass range. Further, we investigate the behaviour of greybody factor (GF) of RNdS-like BH in bumblebee gravity and find that the probability of wave transmission increases with increasing $L$ but decreases with the increase of $Q$. The behaviour of absorption cross section and sparsity of Hawking radiation for different values of $L$ and $Q$ are also analysed graphically.

gr-qc↗

arXiv2025

Quasinormal modes and greybody factors of charge black hole in bumblebee gravity model

In this paper, we investigate the Dirac field, scalar field and electromagnetic field perturbations of Reissner-Nordstorm-de Sitter (RNdS) and Reissner-Nordstorm-(anti)-de Sitter (RNAdS)-like black holes within the frame work of Einstein-bumblebee gravity. The effective potential, greybody factor and quasinormal modes (QNMs) are also explored by using Dirac equation, Klein-Gordon equation and Maxwell's equation. We find that for RNdS-like black hole increasing the Lorentz violation parameter $L$ consistently leads to decrease in the effective potential for all types of perturbations but for RNAdS case the influence of $L$ varies depending on the types of perturbation. Further for both RNdS and RNAdS-like black holes, increasing charge $Q$ reduces the effective potential in all the perturbations. The greybody factors of all the types of perturbations are also discussed. The results show that the greybody factors depend on the shape of the effective potential: higher (lower) potentials gives lower (higher) greybody factors. The QNMs frequencies of RNdS-like black hole for the massless field perturbations are discussed by using 6th order WKB approximation and Padé approximation. We also analyze the time-domain profiles of the perturbations. The effects of Lorentz violation parameter $L$ and charge $Q$ to the photon sphere radius and shadow radius are also discussed. It is noted that increasing $Q$ and $L$ reduce the rise of shadow radius for RNdS-like black hole.

hep-ph↗

arXiv2025

Quasinormal modes of spherically symmetric black hole with cosmological constant and global monopole in bumblebee gravity

This paper studies the scalar, electromagnetic field and Dirac field perturbations of spherically symmetric black hole within the framework of Einstein-bumblebee gravity model with global monopole and cosmological constant. We investigate the effective potentials, greybody factors and quasinormal modes (QNMs) by applying the Klein-Gordon equation, electromagnetic field equation and Dirac equation expressed in Newman-Penrose (NP) formalism. Using the general method of rigorous bound, the greybody factors of scalar, electromagnetic and Dirac field are derived. Applying the sixth order WKB approximation and Padé approximation, the QNM frequencies are derived. We also discuss the impact of global monopole $η$, cosmological constant $Λ$ and Lorentz violation parameter $L$ to the effective potential, greybody factor and QNMs. Increasing the parameter $η$ prevents the rise of effective potential for both Schwarzschild-de Sitter (SdS)-like and Schwarzschild-Anti de Sitter (SAdS)-like black holes with global monopole and consequently increases the greybody factors. However, decreasing the parameter $L$ reduces the rise of effective potential for the SAdS-like black hole with global monopole and it increases the greybody factor but increasing the parameter $L$ has an opposite effect for SdS-like black hole with global monopole. It is also shown that the shadow radius increases with increasing the parameter $η$ for both dS and AdS cases. Increasing the value of $L$ tends to increase the shadow radius for dS black hole but it has an opposite effect in AdS case. A careful studying is being carried out to investigate how the absorption cross-section gets affected when the parameter $L$ appears into the picture.

gr-qc↗

arXiv2024

Greybody factor and Quasinormal modes of scalar and Dirac field perturbation in Schwarzschild-de Sitter-like black hole in Bumblebee gravity model

In this paper, we study the scalar and Dirac fields perturbation of Schwarzschild-de Sitter-like black hole in bumblebee gravity model. The effective potentials, greybody factors and quasinormal modes of the black hole are investigated by using the Klein-Gordon equation and Dirac equation. To compute the greybody factors for scalar and Dirac fields, we use the general method of rigorous bound. We also investigate the quasinormal mode using the third order WKB approximation method and Pöschl-Teller fitting method. The impact of Lorentz invariance violation parameter $L$ and cosmological constant $Λ$ to the effective potential, greybody factors and quasinormal modes are analyzed for different modes. Increasing the parameters $Λ$ and $L$ lower the effective potentials and consequently increases the rigorous bound on the greybody factors. Our findings show that the oscillation frequency and the damping rate decrease with increasing $L$. We analyze the Hawking temperature, power spectrum and sparsity of Hawking radiation. Both the peak of power spectrum and total power emitted decrease with increasing $L$. The effect of $L$ on the shadow radius is also discussed.

hep-ph↗

arXiv2024

Maxwell's equal-area law for Vaidya-Bonner-de Sitter black hole under Lorentz invariance violation

In this paper, we investigate the tunneling of fermions with arbitrary spin near the event horizon of non-stationary Vaidya-Bonner-de Sitter black hole (VBdS) in Lorentz invariance violation (LIV). The modified Hawking temperature of VBdS black holes is calculated by using tortoise coordinate transformation, Feynman prescription and WKB approximation. By considering cosmological constant as a thermodynamic pressure in the extended phase space, we construct Maxwell's equal-area law in LIV and study the phase transitions of VBdS black hole in P-v, P-V and T-S plane. The LIV increases the length of liquid-gas coexistence region. The thermodynamic quantities such as entropy, heat capacity, Helmholtz free energy, Internal energy, enthalpy and Gibbs free energy of VBdS black hole are discussed. These quantities tend to increase under LIV. The stability of black hole is also discussed in the presence of LIV.

hep-ph↗

arXiv2023

Massive vector particle tunneling from Kerr-Newman-de Sitter black hole under generalized uncertainty principle

The quantum tunneling of charged massive vector boson particles across the event horizon of Kerr-Newman-de Sitter black hole is investigated under the influence of quantum gravity effects. The modified Hawking temperatures and heat capacities across the event horizon of KNdS black hole are derived in 3-dimensional and 4-dimensional frame dragging coordinates. It is found that due to quantum gravity effects the modified Hawking temperatures and heat capacities depend on the mass and angular momentum of the emitted vector boson particles. For 3-dimensional KNdS black hole, the modified Hawking temperature is lower than the original Hawking temperature but the modified heat capacity is higher than the original heat capacity due to quantum gravity effects. In the case of 4-dimensional KNdS black hole, the modified Hawking temperature and heat capacity are lower or greater than the original Hawking temperature and heat capacity depending upon the choices of black hole parameters due to quantum gravity effects. We also discuss the remnant and graphical analysis of the modified Hawking temperatures and heat capacities.

gr-qc↗