arXiv subjects

Faisal Javed

Publications and source records attributed to Faisal Javed.

At least 19 recordsLinked to original sources

arXiv2026

Harmonic oscillation and orbital morphology for spinning charged quantum corrected black hole

This study investigates the dynamical behavior of particle's test around a spinning charged Einstein-Maxwell-dilaton (EMd) quantum corrected black hole (QCBH) by examining the effects of spinning parameter $a$, quantum correction parameter $b$, and charge parameter $Q$. Using EMd spacetime geometry, we analyze the effective potential and effective force to determine the stability and structure of the circular orbits in a strong gravitational field. Furthermore, we calculate the oscillation frequencies radial $(Ω_r)$, vertical $(Ω_θ)$, and angular $(Ω_ϕ)$, as well as the corresponding Periapsis and Lense-Thirring precession frequencies. The spin parameter primarily determines the spinning properties of spacetime, while the quantum correction and charge particle introduce additional biases to Kerr-Newman geometry, particularly near the event horizon. These corrections alter the position and stability of the circular orbits, and the spectrum effectively associates with particle's motion. The results provide a comprehensive description of the orbital dynamics of spinning EMd QCBH through future high-precision astrophysical observations.

gr-qc↗

arXiv2026

Impact of deformation parameters on the greybody factor and Joule-Thomson expansions of Schwarzschild-AdS black hole

This paper investigates the greybody factor and Joule-Thomson expansion of deformed Schwarzschild-AdS black hole models. We constructed the Klein-Gordon equation into a Schrödinger-like wave equation using tortoise coordinates and derived the exact effective potential. Also, we analyzed its behavior under varying physical parameters, including deformation parameters, mass and angular momentum. In this case, our results illustrate that increasing the deformation parameter enhances the effective potential, significantly impacting the absorption and scattering of massless scalar fields. It is noted that the Schwarzschild black hole effective potential is greatly increased when the deformation parameter is present. Near the event horizon, we found that waves behave differently, with higher-frequency waves more easily penetrating potential obstacles and lower-frequency waves bouncing off them. Furthermore, we investigated the thermodynamic characteristics of black holes using the Joule-Thomson expansion, detecting isenthalpic curves that indicate heating and cooling zones controlled by pressure and temperature changes. In this context, we tested the influence of deformation black hole parameters; the isenthalpic curves are enhanced by increasing the deformation parameters and the black hole mass.

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arXiv2026

Topological analysis of novel charged-AdS black hole solutions embedded in dark matter halos with quintessence field

In this work, we investigate the properties of a charged anti-de Sitter (AdS) black hole in the presence of a NGC 4649-type dark matter halo and a surrounding quintessence field. Starting from the modified Einstein field equations (EFEs), we construct the corresponding black hole solutions by incorporating the effects of electric charge, cosmological constant, dark matter distribution, and quintessence characterized by a variable equation of state. We analyze the resulting spacetime geometry through the metric function and horizon structure, showing that the dark matter halo strengthens the gravitational attraction, whereas the quintessence field provides a repulsive contribution that substantially alters the asymptotic behavior of the spacetime. Furthermore, the thermodynamic properties are investigated by applying the Duan-$ϕ$-mapping topological theory together with the generalized free energy method. This framework allows us to examine the topological structure, critical behavior, and stability conditions of the black hole system in a consistent manner. We further study the fractional shifts relative to the reference value of $ω_q$ and observe that variations in $ω_q$ produce systematic changes which highlight the important role of the quintessence field in determining the phase structure and critical behavior of the black hole system.

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arXiv2026

Onset of Chaos and Orbital Instabilities around Rotating Weyl Black Holes

We investigate nonlinear photon motion in the vicinity of a rotating black hole (BH) within Weyl conformal gravity (WCG) by employing Poincare sections, Lyapunov exponents, Fast Lyapunov Indicators (FLI), Kolmogorov-Sinai (KS) entropy, and Discrete Indicator of Chaos (DIG) maps. The joint influence of BH spin and higher order curvature corrections, governed by the parameters $ξ$ and $γ$, induces a transition from nearly integrable trajectories to markedly chaotic dynamics in the strong field domain. As $ξ$ and $γ$ increase, the invariant tori are increasingly deformed and eventually break up. Resonance islands and stochastic layers then form, producing large chaotic regions in phase space, especially near the extremal spin regime. Increasing Lyapunov exponents, faster FLI growth, and higher KS entropy provide quantitative measures of the enhanced dynamical instability, the increased sensitivity to initial conditions, and the corresponding rate of information production. DIG maps show shrinking regular regions and expanding chaotic domains around the photon sphere, indicating that conformal gravity corrections destabilize null circular orbits. Taken together, these findings clarify how relativistic frame dragging and higher order curvature terms jointly control photon chaos and point to nonlinear photon dynamics as a potential probe of departures from General Relativity in the strong-gravity regime.

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arXiv2026

Magnetically charged spinning particles around a regular black hole: constraints on the monopole charge from quasi-periodic oscillations

We investigate the dynamics of magnetically charged spinning test particles in the spacetime of the Bardeen regular black hole, sourced by nonlinear electrodynamics and featuring a magnetic monopole charge parameter g. Using the Mathisson-Papapetrou-Dixon equations with the Tulczyjew spin condition, extended by the Coulomb-like force between the particle's magnetic charge and the monopole, we derive the effective potential for equatorial motion and analyze circular orbits, the innermost stable circular orbit (ISCO), superluminality constraints and high-energy collisions. Solving the ISCO conditions perturbatively around Schwarzschild, we obtain exact coefficients, r_{\rm ISCO}, and show that the magnetic coupling λg shifts r_{\rm ISCO} only at higher order while it changes the ISCO energy and angular momentum at first order. We compute radiative efficiencies (up to \simeq 8\% in the explored range, against 5.72\% for Schwarzschild) and the orbital and radial epicyclic frequencies, including the ISCO and the 3:2 resonance, whose frequency at fixed mass is shifted by 5--11\% for g/M=0.5--0.7.

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arXiv2026

Energy-momentum-squared gravity: charged quark star solutions with unified interacting matter

We investigate the equilibrium structure of electrically charged quark stars within the framework of energy-momentum-squared gravity (EMSG), adopting a unified interacting quark-matter equation of state that incorporates perturbative QCD corrections, color superconductivity, and finite-strange-quark-mass effects. By solving the modified Tolman-Oppenheimer-Volkoff equations over a broad range of EMSG coupling strengths and interaction parameters, we show that the inclusion of electric charge substantially increases both the maximum mass and radius compared with neutral configurations. For strong negative couplings and pronounced interaction strengths, the resulting stellar models reach masses close to $3,M_{\odot}$ with compactness ratios of order $0.34$, placing them within the mass range inferred for the secondary component of GW190814, whose nature remains observationally undetermined. The presence of charge reduces the central density at maximum mass by approximately $10$--$15\%$ while maintaining full compliance with causality requirements. Furthermore, comparisons with observational constraints from PSR J1614$-$2230, J0348$+$0432, J0740$+$6620, J0952$-$0607, and recent NICER radius measurements indicate that charged EMSG configurations remain consistent with current astrophysical bounds over a wide parameter space. These results demonstrate that a moderate electric charge, when combined with nonlinear matter-geometry coupling, can support quark stars that are significantly more massive than those predicted in general relativity, underscoring the potential observational relevance of charged compact objects in modified gravity and multimessenger astrophysics.

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arXiv2026

Dynamical Structure of Einasto Dark Matter Wormholes: Thin-Shell Stability and Particle Transitions

In this manuscript, we develop topologically charged static and spherically symmetric wormhole (WH) configurations in Einstein gravity by employing the Einasto dark matter profile to construct an analytic shape function. The resulting spacetime satisfies the fundamental traversability conditions, while the matter sector exhibits localized violations of energy conditions near the throat, indicating confined exotic matter content. We analyze equilibrium through the TOV framework, revealing a non-equilibrium force competition in which hydrostatic and anisotropic contributions self-organize to sustain static configurations within specific parameter domains. Stability is examined via the anisotropy parameter and further extended to linearized radial perturbations of the surrounding shell, uncovering parameter-dependent stability windows that characterize the system's nonlinear response. A detailed dynamical analysis shows that the monopole charge parameter significantly restructures the effective potential landscape, modifying curvature and inducing qualitative transitions in particle motion. The coupled interplay between monopole charge, angular momentum, and particle energy governs a nonlinear transition from tightly wound quasi-bound states to unbounded scattering trajectories. This transition reflects an emergent dynamical phase structure in the WH spacetime. Furthermore, the complexity factor exhibits strong localization near the throat and vanishes asymptotically, indicating that structural complexity is confined to the inner nonlinear regime, whereas a volume integral quantifier is employed to estimate the total exotic matter content required to sustain the configuration.

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arXiv2026

Periodic orbits and gravitational wave signatures from magnetic dipoles around magnetized Kerr black holes

We study periodic orbits and the associated gravitational radiation of a magnetized (uncharged) test particle carrying a magnetic dipole moment with coupling constant beta, moving in the equatorial plane of a rotating, magnetized Kerr black hole immersed in an external asymptotically uniform magnetic field, starting from the effective potential derived for such particles. We compute the marginally bound orbit (MBO) and the innermost stable circular orbit (ISCO) as functions of the black hole spin a and the magnetic coupling beta, and map out the allowed region of the orbital energy-angular momentum (L, E) plane for bound motion. We then classify periodic orbits using the topological zoom-whirl scheme of Levin and Perez-Giz, characterized by three integers (z,w,v) through the rational rotation number q=w+v/z, and construct a family of closed rosette orbits at fixed angular momentum. Using the numerical-kludge, restricted-quadrupole approximation for an extreme-mass-ratio inspiral consisting of a stellar-mass magnetized secondary orbiting a supermassive magnetized Kerr black hole, we compute the time-domain gravitational waveforms h_+(t), h_\times(t) produced by these periodic orbits and their frequency-domain characteristic strain, and compare the latter with the anticipated instrumental sensitivity curves of LISA, Taiji and TianQin. We find that the magnetic coupling βsystematically shifts the MBO and ISCO outward and lowers their orbital energy and angular momentum, that the zoom-whirl structure of the periodic orbits is imprinted directly on the burst-like morphology of the emitted waveform, and that the resulting gravitational-wave signals fall within the sensitivity band of upcoming space-based detectors for suitably close and massive sources.

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arXiv2026

Circular-orbit dynamics and QPO constraints in static Einstein--scalar--Gauss--Bonnet black holes

Einstein--scalar--Gauss--Bonnet (EsGB) gravity provides a physically motivated framework for testing strong-field deviations from the Schwarzschild geometry through scalar hair. We study neutral-particle circular motion and high-frequency quasi-periodic oscillations (HF-QPOs) in static EsGB black holes described by a continued-fraction metric with a single dimensionless deformation parameter $p$ on the Schwarzschild-connected quadratic-coupling branch. We determine the effective potential, circular-orbit energy and angular momentum, characteristic radii, and orbital and radial epicyclic frequencies, and apply the relativistic precession model to twin-peak QPO data from XTE J1550--564, GRO J1655--40, GRS 1915+105, and M82 X-1. A source-by-source Markov chain Monte Carlo analysis shows that the observed frequency pairs can be reproduced within their uncertainties and that the radial epicyclic frequency carries the main model-level sensitivity to $p$. However, a controlled prior-sensitivity analysis using uniform and truncated Gaussian priors finds that the marginal posterior of $p$ closely follows the adopted prior for all four sources. This reflects the intrinsic underconstraint of fitting three correlated parameters $(M,p,r)$ to two measured frequencies. The inferred intervals therefore represent model-dependent compatibility regions rather than an independent measurement or preferred value of the EsGB deformation. The static results provide a baseline for future rotating and multi-observable tests.

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arXiv2026

Grey-Body Factors and Thermodynamics of Asymptotically de Sitter Black Holes in Generalized Proca Theory

Generalized Proca theory supplements gravity with a massive vector field whose derivative self-interactions can support black holes carrying primary vector hair. In the asymptotically de Sitter branch considered here, the de Sitter scale is effective: it is generated by the vector sector rather than imposed through a bare cosmological-constant term. We compute grey-body factors and effective absorption cross-sections for massive scalar, electromagnetic, and massless Dirac test fields on this background. The transmission curves are obtained from a sixth-order WKB barrier calculation and are compared with the quasinormal-mode reconstruction; the two descriptions mostly agree, with small visible differences at lower mutlipoles. Increasing the scalar mass raises and broadens the scalar barrier, suppresses transmission at fixed frequency, and shifts efficient transmission to higher frequencies. The couplings considerably affect the grey-body factors and black hole thermodynamics.

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arXiv2026

Thermal aspects and particle dynamics of Euler-Heisenberg AdS black hole in 4D Einstein Gauss-Bonnet gravity

We construct charged AdS black hole solutions in four dimensional Einstein Gauss Bonnet gravity coupled to Euler Heisenberg nonlinear electrodynamics and investigate their physical properties. The modified field equations admit black hole solutions whose horizon structure is significantly affected by higher-curvature and nonlinear electromagnetic corrections, allowing for multiple horizons depending on the model parameters. In the extended phase space, where the cosmological constant is interpreted as thermodynamic pressure, we analyze the thermodynamic behavior and show that both the Gauss Bonnet coupling and the Euler Heisenberg parameter induce notable modifications in the equation of state, critical behavior, and thermal stability. Interpreting the black hole mass as enthalpy, we study the Joule-Thomson expansion and determine the inversion temperature and pressure, demonstrating that higher curvature and nonlinear electrodynamic effects substantially influence the cooling and heating regions. Finally, we examine time-like geodesics and show that Gauss Bonnet corrections significantly modify the effective potential, orbital stability, and particle motion in the strong-field regime

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arXiv2025

Origin of Quasi-Periodic Oscillations and Accretion Process in X-Ray Binaries around Quantum Lee-Wick Black Hole

In this study, we investigate the accretion dynamics and test particle motion around a non-rotating, spherically symmetric Lee-Wick black hole (BH) to reveal how the model parameters affect orbital stability and the quasi-periodic oscillations (QPOs) observed in X-ray binary systems. The spacetime geometry, characterized by the BH mass and the coupling parameters $S_1$ and $S_2$, includes exponential and oscillatory corrections arising from the Lee-Wick terms. Using the effective potential approach, we derive specific energy, angular momentum, epicyclic frequencies, and the locations of the innermost stable circular orbits (ISCOs) of test particles. In addition to the analytical analysis, we explore the effects of the Lee-Wick spacetime parameters on the shock-cone morphology produced by Bondi-Hoyle-Lyttleton (BHL) accretion. To this end, we perform general relativistic hydrodynamic simulations in two characteristic regimes: Block-1 (weak Lee-Wick regime) and Block-2 (strong Lee-Wick regime). The results show that Block-1 solutions closely resemble the Schwarzschild case, while Block-2 models develop denser and asymmetric shock cones accompanied by stronger QPOs activity, shifting from low-frequency to high-frequency QPOs. These variations yield distinct observational signatures that may be detectable in high-resolution X-ray timing data. Our analytical and numerical findings demonstrate that the Lee-Wick parameters $S_1$ and $S_2$ cause measurable changes in the morphology of the accretion flow and in the frequency ratios near the BH. This suggests that future multi-wavelength observations could provide an important avenue to test higher-derivative gravity theories.

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arXiv2025

Magnetized particle motion and accretion process with shock cone morphology around a decoupled hairy black holes

Relativistic accretion onto compact objects such as black holes and neutron stars is one of the most efficient known mechanisms for converting gravitational potential energy into radiation. In the case of rapidly spinning black holes, up to $40\%$ of the rest-mass energy of accreting matter can be released, far exceeding the efficiency of nuclear fusion. In this work, we investigate magnetized particle motion and relativistic accretion processes around a decoupled hairy black hole via extended geometric deformation. The developed geometry involves two hairy parameters that preserve the horizon structure with the additional feature of the fulfillment of weak energy conditions outside the event horizon. We provide the foundation with necessary formalism for magnetized particle motion around a decoupled black hole. The effective potential and innermost stable circular orbits are then derived, which demonstrate a significant reduction of the radius of the latter quantity under the hairy parameters for the magnetized particle. Afterwards, we obtain exact analytical expressions for radial velocity profiles, mass accretion rates, and a few others which reveal improved energy efficiency and emissivity as compared to the standard black hole. Furthermore, the decoupling parameter shows strong influence on oscillations, accretion presenting fantastic agreement between analytical predictions and numerical simulations, and thus offering noticeable observational signatures for future gravitational wave and X-ray astronomy.

astro-ph.HE↗

arXiv2025

Study of Complexity Factor and Stability of Dynamical Systems in $f(G)$ Gravity

In this paper, we evaluate the complexity of the non-static cylindrical geometry with anisotropic matter configuration in the framework of modified Gauss-Bonnet theory. In this perspective, we calculate modified field equations, the C energy formula, and the mass function that helps to understand the astrophysical structures in this modified gravity. Furthermore, we use the Weyl tensor and obtain different structure scalars by orthogonally splitting the Riemann tensor. One of these scalars, $YTF$ is referred to as the complexity factor. This parameter measures the system's complexity due to non-uniform energy density and non-isotropic pressure. We select the identical complexity factor for the structure as used in the non-static scenario while considering the analogous criterion for the most elementary pattern of development. This technique involves formulating structural scalars that illustrate the fundamental features of the system. A fluid distribution that satisfies the vanishing complexity requirement and evolves homologously is characterized as isotropic, geodesic, homogeneous, and shear-free. In the dissipative scenario, the fluid remains geodesic while exhibiting shear, resulting in an extensive array of solutions.

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arXiv2024

Extracting $H_{0}$ and $r_{d}$ in Pacif Parametrization Models through Late-Time Dataset

This study examines five models derived from the Pacif parametrization scheme of the Hubble parameter ($H$), yielding various linear to quintic forms of the deceleration parameter (DP). Our goal is to explore the impact of these DP variations on late-time evolution and their potential to alleviate cosmological tensions. To enhance model constraints, we introduce non-diagonal elements into the covariance matrix to better capture statistical properties by simulating data point correlations. We also test the sensitivity of $H_{0}$ and $r_{d}$ to the Pacif parametrization scheme, treating the sound horizon $r_{d}$ as a free parameter to avoid imposing a CMB prior. This allows late-time data to constrain $r_{d}$ alongside other cosmological parameters, incorporating recent Baryon Acoustic Oscillations (BAO) measurements and Hubble data from Cosmic Chronometers Methods, Type Ia Supernovae (SNIa), Gamma-Ray Bursts (GRBs), and Quasars over a redshift range of $0.106 < z < 2.33$. Our analysis provides optimal fit values for $H_{0}$ and $r_{d}$, showing notable consistency with Planck CMB data. By using the Akaike information criterion, we analyze the models and conclude that all models have good agreement with the most recent observations.

astro-ph.CO↗

arXiv2024

Exploring the viability of charged Spheres admitting non-metricity and matter source

This research paper investigates the impact of non-metricity and matter source on the geometry of charged spheres in the presence of anisotropic matter configuration. We use a specific model of extended symmetric teleparallel theory to minimize the complexity of the field equations. Moreover, the feasible non-singular solutions are used to examine the interior composition of the charged spheres. The Darmois junction conditions are used to determine the unknown constants in the metric coefficients. We explore some significant properties in the interior of compact stars under consideration to check their viable existence in this modified framework. The equilibrium state of the charged spheres is discussed using the Tolman-Oppenheimer-Volkoff equation and stability is analyzed by sound speed and Herrera cracking approach. We find that the charged spheres in this theoretical framework are physically viable and stable.

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arXiv2024

Viable Wormhole Structures and Energy Conditions in f(Q,T) Theory

This paper explores static wormhole solutions in f(Q,T) theory, where Q is the non-metricity and T is the trace of energy-momentum tensor. We derive the field equations that describe gravitational phenomena in the existence of non-metricity and matter source terms. We examine different models of this theory to determine the explicit expressions of matter contents, which are useful for analyzing the wormhole structures. We investigate the existence of feasible traversable wormhole solutions for constant and variable redshift functions. To determine whether physically viable wormhole geometry exists, we examine the graphical interpretation of energy constraints for different values of model parameters. It is found that realistic traversable and stable wormhole solutions exist only for the first model of this gravity.

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arXiv2024

Novel Gravastar Solutions: Investigating Stability, Energy, and Entropy in the Presence of Cloud of Strings and Quintessence

Gravastars, theoretical alternatives to black holes, have captured the interest of scientists in astrophysics due to their unique properties. This paper aims to further investigate the exact solution of a novel gravastar model based on the Mazur-Mottola (2004) method within the framework of general relativity, specifically by incorporating the cloud of strings and quintessence. By analyzing the gravitational field and energy density of gravastars, valuable insights into the nature of compact objects in the universe can be gained. Understanding the stability of gravastars is also crucial for our comprehension of black holes and alternative compact objects. For this purpose, we present the Einstein field equations with the modified matter source and calculate the exact solutions for the inner and intermediate regions of gravastars. The exterior region is considered as a black hole surrounded by the cloud of strings and quintessence, and the spacetimes are matched using the Darmoise-Israel formalism. {An investigation is conducted on the stability of gravastars using linearized radial perturbation. Additionally, the proper length, energy content, and entropy of the shell are computed. The stability of gravastars is positively correlated with the enhancement of the cloud of strings parameter, while it is negatively correlated with the growth in the quintessence field parameter.} The paper concludes with a summary of the findings and their implications in the field of astrophysics and cosmology.

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