212 citations · 6.6k across the 163 of their papers we have counts for
162 papers
Maxwell-Jttner averaged nonaffine theory of relativistic shear viscosity
Reggie C. Pantig, Ali Övgün
We formulate a Maxwell-Jüttner averaged extension of relativistic nonaffine shear-viscosity theory for a classical gas of massive particles. The starting point is the relativistic…
Redshift Spectroscopy as a Probe of Regular Black Holes, Black Bounces, and Scalar-Hair Compact Objects
Ali Övgün, Reggie C. Pantig, Joel Saavedra
Motivated by [Phys. Rev. D. 107, 064019 (2023)], we develop a unified and model-independent framework for the spectroscopy of photon frequency shifts in generic static, spherically…
Fixed ADM reconstruction of extended uncertainty principle black holes
Nikko John Leo S. Lobos, Ali Övgün, Reggie C. Pantig
We study a phenomenological fixed-ADM prescription for an extended-uncertainty-principle (EUP) correction to the Schwarzschild exterior. Rather than treat mass constancy as a conse…
Chromatic Weak Lensing by Charged Black Holes with Two Lorentz-Violating Kalb-Ramond Couplings
Ali Övgün, Reggie C. Pantig, Grigoris Panotopoulos
We study weak gravitational lensing and steady spherical test--fluid accretion by a static charged black hole in a Lorentz--violating Kalb--Ramond background with two nonminimal cu…
Phase-plane formulation of weak gravitational deflection in static spherical spacetimes
Reggie C. Pantig, Ali Övgün
This paper develops a phase-plane formulation of gravitational light deflection by static and spherically symmetric black holes, with Schwarzschild spacetime as the principal case.…
Spinning Particle Dynamics and Observational Redshift around an Asymptotically Flat Symmergent Black Hole
Beyhan Puliçe, Ali Övgün
We investigate timelike particle dynamics, collision energetics, and photon frequency shifts in the perturbative variable-scalar curvature branch of asymptotically flat symmergent…
Density-preserving core-Einasto black holes with Event Horizon Telescope bounds
Ali Övgün, Reggie C. Pantig
A Newtonian halo density does not uniquely determine a relativistic spacetime, and the resulting completion ambiguity can dominate predicted horizon-scale signals. We make this dep…
An obstruction and residual-completion theory for Newman--Janis deformations
Reggie C. Pantig, Ali Övgün
We formulate an obstruction and residual-completion theory for Newman-Janis-type deformations of black hole seeds, where Newman-Janis-type includes both the original complex-coordi…
Shadow of the generalized Vaidya black hole
Vitalii Vertogradov, Ali Övgün
In this paper, we investigate the shadow of the generalized Vaidya black hole described by the Husain solution. Assuming a barotropic equation of state for the additional matter se…
Can finite-density QCD matter support a regular black hole core?
G. Lambiase, A. Övgün, V. Vertogradov
We investigate whether finite-density QCD matter can provide the stress-energy needed to regularize the center of a spherically symmetric black hole collapse. In a generalized Vaid…
Equatorial periodic orbits and gravitational wave signatures in Euler-Heisenberg black holes surrounded by perfect fluid dark matter
Dhruba Jyoti Gogoi, Jyatsnasree Bora, Ali Övgün
We investigate equatorial periodic orbits and their gravitational wave radiation in the spacetime of an Euler--Heisenberg (EH) black hole surrounded by perfect fluid dark matter (P…
Echoes of a hairy black hole from gravitational decoupling
Yi Yang, Ali Ovgun, Gaetano Lambiase +2
We study axial gravitational perturbations of a hairy black hole constructed within the framework of gravitational decoupling and investigate the geometric origin of echo-like late…
Josephson Effects in Slowly Rotating Spacetimes
Nurmukhammed Aytimbetov, Reggie C. Pantig, Ali Övgün +2
We investigate Josephson phenomena in a slowly rotating stationary spacetime, emphasizing the distinct roles of gravitational redshift and rotational frame dragging motivated by [1…
Horizon-Brightened Acceleration Radiation and Optical Signatures of Generic Regular Black Holes from Nonlinear Electrodynamics
Uktamjon Uktamov, Ali Övgün, Reggie C. Pantig +1
We investigate horizon-brightened acceleration radiation (HBAR) and optical signatures for a broad class of regular black holes sourced by nonlinear electrodynamics. The spacetimes…
Radial Integral Reformulation of the Gauss-Bonnet Weak Deflection Angle at Finite Distance
Ali Övgün, Reggie C. Pantig
We develop a radial integral reformulation of finite distance gravitational lensing in optical geometry for static, spherically symmetric spacetimes. Starting from the Gauss-Bonnet…
Acceleration Radiation of Freely Falling Atoms: Nonlinear Electrodynamic Effects
Ali Övgün, Reggie C. Pantig, Bobomurat Ahmedov +1
Motivated by the work of Scully \textit{et al.} [ \textcolor{blue}{Proc. Nat. Acad. Sci. 115, 8131 (2018)}] and Camblong \textit{et al.}[ \textcolor{blue}{Phys. Rev. D 102, 085010…
Lorentz-violating modifications to particle dynamics, thermodynamics and vacuum energy in bumblebee gravity
A. A. Araújo Filho, K. E. L. de Farias, E. Passos +5
We investigate how spontaneous Lorentz symmetry breaking in bumblebee gravity modifies particle dynamics, thermodynamics, and vacuum energy around a static black hole background. S…
Boundary-only weak deflection angles from isothermal optical geometry
Ali Övgün, Reggie C. Pantig
We develop a boundary only method for computing weak gravitational deflection angles at finite source and receiver distances within the Gauss-Bonnet theorem formulation of optical…
Acceleration radiation from vibrating atoms in Schwarzschild spacetime
Reggie C. Pantig, Ali Övgün, Syed Masood +1
Motivated by the work of Scully \textit{et al.} [ \textcolor{blue}{Proc. Nat. Acad. Sci. 115, 8131 (2018)}] and Dolan \textit{et al.}[ \textcolor{blue}{New J. Phys. 22, 033026 (202…
Quasinormal Mode Spectroscopy via Horizon-Brightened Quantum Optics
Ali Övgün
We develop a quantum optical framework for probing black hole quasinormal modes (QNMs) using two-level atoms in the spirit of the horizon-brightened acceleration radiation (HBAR) p…
Josephson's effect in the Schwarzschild background
Reggie C. Pantig, Ali Övgün
We develop a fully covariant, analytic framework for Josephson phenomena in static curved spacetimes and specialize it to the Schwarzschild exterior. The formulation rests on two i…
Acceleration Radiation from Derivative-Coupled Atoms Falling in Modified Gravity Black Holes
Reggie C. Pantig, Ali Övgün
The interaction of quantum detector models with fields in curved spacetimes provides fundamental insights into phenomena such as Hawking and Unruh radiation. While standard models…
Semi-Analytic Trajectory Analysis of Light in Generic Static Spacetimes
Ali Övgün, Reggie C. Pantig
We study a unified semi-analytical framework to study null geodesics and weak-field light deflection in generic static, spherically symmetric spacetimes of the form \(ds^2 = -α(r,δ…
The Sound of an Orbit: A Quantum Spectrum at the ISCO
Reggie C. Pantig, Ali Övgün
We investigate the quantum signature of the innermost stable circular orbit (ISCO), a region of profound importance in black hole astrophysics. By modeling an atom as an Unruh-DeWi…