General Relativity and Quantum Cosmology
We construct an exact vacuum spacetime that develops closed timelike curves from regular, asymptotically flat initial data respecting the weak, dominant, and strong energy conditions. Einstein's equations fix the geometry through two…
We construct a residue-based framework connecting the thermodynamic geometry of a Schwarzschild-type black hole in $f(Q)$ gravity with its gravitational-wave quasinormal-mode spectrum. The analysis is based on the symmetric teleparallel…
The intrinsic spin of fermions induces torsion in spacetime, leading to an effective four-fermion interaction. This affects the bending of null and timelike geodesics inside a star with a spherically symmetric distribution of…
Information geometry has traditionally been formulated within the framework of Riemannian geometry and dual affine connections. In this work, we reframe this foundational structure by introducing the geometric machinery of symmetric…
Compact objects with black-hole-like exteriors may hide new strong-field physics in their interiors, making their dynamical response a sensitive probe of gravity beyond General Relativity. We present an analytically tractable,…
Gravitational wave (GW) polarizations are traditionally classified in a fixed frame ($E(2)$ classification), which does not account for how polarization patterns change under Lorentz boosts. In this work, we derive the explicit…
In this paper, we employ spinning test particles as probes to investigate the regulatory effects of particle and black hole parameters on the violation of the chaos bound in Kerr-Newman-AdS spacetime. Our results demonstrate that the chaos…
In a recent article, Hod [1] has concluded the non-existence, heretofore unnoticed, of a unified Thorne's hoop conjecture that holds for the quasi-local mass, $\mathcal{M}(r\leq R_{+})$ for static Reissner-Nordstr\H{o}m black hole, but does…
The Damour-Solodukhin wormhole (hereinafter DSWH) is known to mimic Schwarzschild black hole (hereinafter SBH) horizon in some properties. To act as a mimicker, the DSWH parameter $\lambda$ by definition is required to be extremely tiny,…
We present a covariant mechanism in which a smooth change of metric signature, from a Euclidean to a Lorentzian regime, drives a finite interval of accelerated expansion. The transition, encoded by a scalar interpolator along a timelike…
In this work, we examine the theoretical framework of modified teleparallel gravity with the inclusion of the boundary term in the action and investigate its cosmological implications by considering the power-law model $f(T, B) = -T +…
We extend our study of a cosmological scenario in which dark matter is non-minimally coupled to gravity at the fluid level. In previous work, we showed that this interaction can drive an early phase of accelerated expansion, addressing the…
We investigate the cosmological implications of the mass-to-horizon relation, which provides a unified framework for thermodynamically consistent generalized horizon-entropy functionals. Using the Cai-Kim formulation of the first law of…
We investigate the field of a point-like electric charge freely falling in a gravitational wave. In the presence of a gravitational wave, the initially static Coulomb field of the charge becomes time-dependent and generates corresponding…
We develop a geodesic-optics description of eikonal quasinormal ringing, blackhole shadows, strong lensing, grey-body factors (GBFs), and the binding energy of massive particles for the asymptotically flat regular black-hole geometry…
Globular clusters (GCs) can act as gravitational lenses for gravitational waves(GWs) in the wave-optics regime, imprinting frequency-dependent signatures on the observed signal. We investigate whether such lensing effects can be used to…
We consider a very general scale-invariant scalar-tensor theory of gravity and its flat cosmological solutions. We show that any stable configuration with non-degenerate gravitational dynamics carries a non-vanishing cosmological constant,…
Classically, black holes (BHs) are the most compact objects predicted in nature with C=0.5 in the Schwarzschild limit; C is defined as the mass-to-radius ratio in geometric units. In this work we perform a novel measurement on the nature of…
Several gravitational wave (GW) observations have been identified as binary black hole (BBH) mergers, including systems with component masses that challenge typical formation scenarios. These observations motivate broader tests of whether…
Gravitational waves are now routinely detected with ground-based observatories, and, through a process known as Bayesian inference, their source properties are inferred. However, terrestrial noise artifacts, often referred to as glitches,…