General Relativity and Quantum Cosmology
We introduce a static, horizonless, asymptotically flat two throat wormhole family in which one global metric determines the geometry, effective source, null dynamics, lensing, and test field propagation. A finite mass deformation of a…
We present a general construction of charged regular black holes as solutions of a generalization of the Einstein--Maxwell field equations in spherical symmetry in which the Einstein tensor is deformed into an identically conserved tensor…
We show that cosmological models with a semi-infinite phase of slow contraction (ekpyrosis) possess a combination of properties that can address several fundamental problems in cosmology, otherwise faced in contracting de Sitter phases or…
We study a one-loop corrected extension of the classical Callan-Giddings-Harvey-Strominger (CGHS) model of two-dimensional dilaton gravity. The effective action combines the non-local Polyakov action for matter fluctuations, a Polyakov-type…
We present infinite-derivative completions of Quasitopological gravities that are ghost-free, avoid strong coupling instabilities and admit exact, spherically symmetric vacuum regular-black-hole solutions satisfying a perturbative Birkhoff…
The Event Horizon Telescope (EHT) has provided images of the supermassive black-holes Sgr A$^{*}$ and M87$^{*}$, enabling direct tests of gravity. Any extended mass-distribution, such as a dark-matter halo, perturbs null-geodesics in the…
The Hubble tension (HT) represents one of the most significant discrepancies in modern cosmology, with local distance measurements yielding $H_0 = 73.5 \pm 1.4$ km/s/Mpc while cosmic microwave background (CMB) observations predict $H_0 =…
We address the circular motion Unruh effect in 2+1 spacetime dimensions, as probed by a pointlike Unruh-DeWitt detector coupled to a massless scalar field. The effective temperature due to circular acceleration, operationally defined in…
We investigate the phenomenology of black bounce spacetimes through a combined analytical and numerical study of relativistic observables associated with both time-like and null geodesics. Black bounce geometries provide a continuous…
We provide a thorough study of the properties of the Boulware vacuum in the spacetime of a spherical, static thin shell with a Minkowski interior. To this end, we calculate the renormalized vacuum polarization and stress-energy tensor of…
We investigated the influence of a plasma environment on the optical and perturbative properties of a black hole with a topological defect, characterized by the parameter \(k\). We first established a straightforward correspondence between…
In this paper, we study the deflection of massless particles due to a rotating, axially symmetric Kerr-Bertotti-Robinson (KBR) black hole via; material medium approach. We explored the effect of spacetime geometry on the trajectory of light…
Finding rotating black hole solutions in higher-curvature theories of gravity is a problem of fundamental importance. Virtually every approach to reconcile gravity with quantum mechanics predicts corrections to the Einstein-Hilbert action,…
It was previously shown that $H_0$ influences gravitational wave propagation beyond simple redshift, by modifying the effective wavenumber. While earlier studies focused on Pulsar Timing Arrays, we analyze the observability of this effect…
The detection of transient gravitational wave signals relies on independent search algorithms that analyse detector data and assign significance measures to candidate events. However, varying performance complicates their interpretation. We…
We investigate the stability of scalarized black holes in Einstein-scalar-Gauss-Bonnet-Ricci theory along their fundamental branches. We show that initially stable solutions first lose nonspherical stability in the eikonal regime, while…
In this work, we investigate the formation of naked singularities for the $3+1$-dimensional Einstein-scalar field system without symmetry assumptions. We generalize the spherically symmetric and self-similar naked-singularity solution…
Gravitational-wave observations of compact binary mergers have enabled precision tests of gravity in the strong-field dynamical regime. Current approaches combine single-event results that assume deviations from General Relativity (GR) are…
The twin paradox is a foundational thought experiment in the special theory of relativity where a returning twin ages less than the one who remains stationary. However, the intricacies of the twin paradox remain relatively underexplored in…
The Bumblebee gravity (BG) model, featuring spontaneous Lorentz symmetry breaking via a vector field non-minimally coupled to curvature, has been widely used to explore Lorentz-violating effects in cosmology. We investigate primordial black…