arXiv subjects

Inomjon Ibragimov

Publications and source records attributed to Inomjon Ibragimov.

5 recordsLinked to original sources

arXiv2025

Nonlinear evolution of anisotropic matter configurations under higher-order curvature corrections

This study examines the dynamical evolution of self-gravitating systems in the presence of exotic matter within the framework of $f(R)$ gravity. Specifically, we have adopted the Starobinsky model $f(R) = R + \alpha R^2$, which incorporates higher-order curvature corrections to describe nonlinear gravitational behavior. The analysis focuses on the nonlinear spherical evolution of anisotropic matter configurations and explains how dark matter influences their physical characteristics. The presence of dark matter is found to significantly affect the radial and tangential pressure distributions, thereby altering the overall dynamics of the system. The model is employed for the compact object $ Her~X-1$ described by the generalized Tolman-Kuchowicz metric, demonstrating a singularity-free behavior of the physical parameters. The results reveal that increasing the parameter $n$ of the generalized Tolman-Kuchowicz metric leads to striking variations in the model characteristics, highlighting its essential role in governing internal structure and evolution of the compact object. The model remains physically viable under different testing criteria like energy conditions, hydrostatic equilibrium condition, adiabatic index, causality conditions, Herrera's Cracking condition and mass-radius relation presented in this work.

gr-qc↗

arXiv2025

Gravitational quasinormal modes of Dymnikova black holes

We investigate gravitational quasinormal modes of the Dymnikova black hole, a regular spacetime in which the central singularity is replaced by a de Sitter core. This geometry, originally proposed as a phenomenological model, also arises naturally in the framework of Asymptotically Safe gravity, where quantum corrections lead to a scale-dependent modification of the Schwarzschild solution. Focusing on axial gravitational perturbations, we compute the dominant quasinormal frequencies using the WKB method with Pad\'e approximants and verify the results with time-domain integration. We find that the introduction of the quantum parameter $l_{\rm cr}$ leads to systematic deviations from the Schwarzschild spectrum: the real oscillation frequency decreases as $l_{\rm cr}$ increases, while the damping rate also becomes smaller, implying longer-lived modes. In the limit of large $l_{\rm cr}$, the quasinormal spectrum smoothly approaches the Schwarzschild case. These results suggest that even though the corrections are localized near the horizon, they leave imprints in the gravitational-wave ringdown which may become accessible to observation with future high-precision detectors.

gr-qc↗

arXiv2025

Dynamics of Interacting Murnaghan-Equation-of-State Fluids with Global Monopole and Nonlinear Power-Yang-Mills Hair in Critical-Dimension AdS Black Holes

We construct and analyze a novel family of exact higher-dimensional black hole solutions in Einstein-Power-Yang-Mills gravity minimally coupled to a scalar field multiplet supporting a global monopole and a surrounding anisotropic ''scalar gas'' whose stress-energy obeys a generalized Murnaghan equation of state. By adopting the Wu-Yang magnetic ansatz for the non-Abelian sector and enforcing the physically motivated radial condition $p_r=-\rho$, the field equations admit closed-form expressions for the matter density and a single-function lapse $F(r)$ expressed in terms of elementary and Gauss hypergeometric functions. The Murnaghan fluid interpolates between a non-linear core and an effective vacuum at a large radius, producing a backreaction encoded by parameters that control the stiffness and scalar-backreaction scale. We perform a systematic survey of classical energy condition, identifying regions of parameter space where the null energy condition/dominant energy condition holds while the strong energy condition is generically violated (phantom-like behavior), and examine curvature invariants to demonstrate that the solutions possess a central curvature singularity for $n>3$. Thermodynamic properties are derived in the extended phase space: explicit formulas for the Hawking temperature, entropy, conjugate potentials, and a generalized Smarr relation are obtained; the heat capacity exhibits divergencies and sign changes that mark local stability boundaries and second-order phase transitions. Varying the Yang-Mills charge, the nonlinearity index, the monopole coupling, and the Murnaghan parameters generates a rich phase behavior structure and topology changes in the defect ($\varphi$-Duan) map. The results underscore the manner in which gauge nonlinearity, topological defects, and dual-polytropic matter collaboratively transform BH thermodynamics and the topology of phase spaces.

gr-qc↗

arXiv2025

Proper-Time Approach in Asymptotic Safety via Black Hole Quasinormal Modes and Grey-body Factors

We study the quasinormal mode spectrum and grey-body factors of black holes in an effectively quantum-corrected spacetime, focusing on the influence of near-horizon modifications on observable quantities. Employing scalar, electromagnetic, and Dirac test fields, we analyze the perturbation equations and extract the fundamental quasinormal frequencies using both the 6th-order WKB method with Pad\'e resummation and time-domain integration. Our results show that quantum corrections near the horizon significantly affect the real and imaginary parts of the quasinormal modes, particularly for low multipole numbers and in the near-extremal regime. We also verify the robustness of the correspondence between quasinormal modes and grey-body factors by comparing WKB results with those reconstructed from the dominant quasinormal modes. Across all field types and parameter ranges considered, the WKB method proves accurate within a few percent, confirming its reliability in probing the impact of near-horizon physics. These findings support the use of quasinormal ringing and Hawking radiation spectra as sensitive tools for testing quantum modifications of black hole spacetimes.

gr-qc↗

arXiv2025

Cosmological implications and causality in $f(R, L_{m}, T)$ gravity theory with observational constraints

In the generalized matter-geometry coupling theory, we investigate the physical characteristics and causality of some new cosmological models for a flat, homogeneous, and isotropic spacetime filled with stiff, radiation, dust, and curvature fluid sources. We obtain a particular cosmological model corresponding to each source fluid, called Models I, II, III, and IV, respectively. We make observational constraints on each model using the joint analysis of $31$ Cosmic Chronometer (CC) Hubble dataset and $1701$ Pantheon+SH0ES datasets to estimate the current values of model parameters. Using these statistical results, we have analyzed the information criteria, effective EoS parameter, causality of the models, and viability of this generalized gravity theory. Subsequently, we investigate the effective equation of state and deceleration parameter for each model. We found that all models in the late-time universe exhibit transit-phase acceleration, and Models I and II show both the early as well as late-time accelerating phase of the expanding universe. We found the current values of the deceleration parameter in the range $-0.8857\le q_{0}\le-0.4279$ with transition redshift $0.4867\le z_{t}\le0.839$ and the effective EoS parameter in the range $-0.9238\le\omega_{eff}\le-0.6186$. We analyzed the square sound speed condition $c_{s}^{2}\le c^{2}$ for each model.

gr-qc↗