General Relativity and Quantum Cosmology
We investigate scalar quasinormal modes and ringdown signals of a rotating loop quantum gravity black hole constructed via the revised Newman--Janis algorithm. The spacetime incorporates two quantum parameters, the polymeric parameter $P$…
This study explores the nonlinear interactions between gravitational waves in an expanding universe. Random ensembles of gravitational waves are evolved numerically in cosmological models whose spatial volumes increase by more than an order…
We investigate the thermodynamic topology of charged AdS black holes in a non-commutative spacetime sourced by Lorentzian-smeared matter distributions. Since exact analytical solutions for the critical thermodynamic quantities are not…
This work provides a critical reassessment of the cosmological models presented in the article "Non-linear interactions in cosmologies with energy exchange" Eur. Phys. J. C 80, 120 (2020) arXiv:1907.06410 . It points out and corrects…
We present a class of regular axisymmetric black hole geometries fully characterized by the parameters $\{{\cal M},a\}$ and possessing the Kerr event horizon. This family interpolates between regular spacetimes, configurations with…
In this work, we investigate the violation of the chaos bound for spinning test particles in Gauss-Bonnet anti-de Sitter spacetime, focusing on the regulatory roles of the Gauss-Bonnet parameter and spacetime dimensionality. In…
We compute the massive particles radial action along hyperboliclike geodesics in various spherically symmetric spacetimes: the standard $4d$ Schwarzschild spacetime, its $d$-dimensional genralization known as Schwarzschild-Tangherlini…
Loop quantum gravity (LQG) predicts quantum modifications to classical black-hole spacetimes, which may leave imprints on the dynamics and gravitational-wave signals of compact objects in the strong-field regime. In this work, we…
We establish a local obstruction to continuous Lorentzian extensions at a class of warped spacelike singularities. The criterion is expressed through two integrability conditions, a monotonicity condition on the relative warp factors, and…
The stochastic dynamics of a grain embedded within a turbulent fluid subject to strong gravitational fields can be formulated as a random walk on a Riemannian manifold. Such curvature-weighted walks provide a framework to model the…
We re-examine spontaneous scalarization of black holes within Starobinsky gravity supplemented by the Gauss-Bonnet invariant. A novel feature is uncovered: scalarized solutions split into two smooth branches that connect at a common minimal…
Embedded boundary summation by parts (SBP) methods define finite differencing based derivative operators with the added feature that the boundary need not coincide with a grid cell, allowing a boundary to be embedded on a regular Cartesian…
Atoms falling freely into a Ba\~{n}ados-Teitelboim-Zanelli (BTZ) black hole in a Boulware-like vacuum are shown to emit radiation with a Planck spectrum at the Hawking temperature $T_{H}$. This leads to thermal Hawking-like radiation for a…
We extend our \texttt{SpectralPINN} solver to the computation of Kerr-Newman quasinormal modes by applying it to solve the system of two coupled master PDEs -- advancing from the single, separable equation of the uncharged Kerr limit to a…
Based on the $\phi$-mapping topological current theory, we systematically investigate the thermodynamic topology of regular Bardeen-AdS-class black holes coupled to nonlinear electrodynamics, a class of singularity-free geometries whose…
We study the nonlinear photon dynamics in quantum improved rotating black hole surrounded by perfect fluid dark matter (PFDM) using several methods of analysis, including Poincar\'e sections, Lyapunov exponents, Kolmogorov-Sinai (KS)…
We investigate the thermodynamic and observable signatures of thin accretion disks surrounding rotating, regular Hayward black holes embedded within a macroscopic dark matter (DM) envelope. The spacetime is rigorously modelled as a…
The classical formation of a Schwarzschild black hole from a regular, non-singular configuration has recently been shown to be impossible within general relativity: the geometry inevitably develops a discontinuity at the origin, a…
The monogamy of quantum entanglement, applied by Almheiri-Marolf-Polchinski-Sully (AMPS) to black holes, obstructs a smooth horizon vacuum after the Page time. We transcribe this argument to Hawking-like phonon radiation from a sonic…
Dark matter near a black hole and effective extra-dimensional corrections can change the same horizon-scale observables. This creates a simple but important question: if an image differs from Kerr, what caused the difference? We study this…