General Relativity and Quantum Cosmology
The black-bounce spacetime provides a regularized modification of the Schwarzschild metric by introducing a free parameter $a$ that eliminates the central singularity while preserving the exterior geometry of a classical black hole. This…
We use Bayesian inference on multi-messenger observations to constrain the parameter space of compact stars in a phenomenological braneworld model inspired by the effective Sahni--Shtanov scenario. Stellar structure is described by modified…
The centre of mass (CoM) of compact binary coalescences (CBCs) occurring in the vicinity of a supermassive black hole, through interaction with an arbitrary third body (e.g., of stellar mass), or in a dense stellar environment, will undergo…
Cones of future and past are rigorously constructed under the horizon of black hole by completions of geodesics continued from causally connected space-time regions outside the black hole interior. Treating the Schwarzschild black hole as a…
We present a numerical relativity study of head-on collisions involving boson stars using initial data inspired by the Bowen-York initial data used to model black hole binaries with punctures. The initial data method preserves the…
We formulate a generally covariant six-field Rational Extended Thermodynamics model (RET$_6$) for relativistic polyatomic gases, with the dynamical pressure as the only non-equilibrium variable. The model is based on a polyatomic extension…
Millihertz gravitational-wave observations with space-based interferometers require time-delay interferometry (TDI) observables whose residual instrumental noise is sufficiently controlled for both detection and parameter inference.…
The Einstein-de Sitter universe is the prevailing model used in cosmology to describe the cold dark matter-dominated epoch of the universe. This model is a spatially homogeneous and isotropic spacetime undergoing decelerated expansion, and…
We present the first self-force-based beyond-GR waveform model incorporating post-adiabatic orbital evolution for intermediate- and extreme-mass-ratio inspirals in theories of gravity with additional scalar fields. Focusing on…
Extreme mass-ratio inspirals (EMRIs) are sensitive probes of weak environmental effects around massive black holes, since such effects can accumulate into observable gravitational-wave phase shifts. In this work, we study the phase…
The James Webb Space Telescope (JWST) has revealed compact, red, overmassive accreting black holes - the so-called ``Little Red Dots'' (LRDs) - in chemically near-pristine hosts at $z\simeq5 - 9$, straining standard heavy-seed models. We…
We investigate the influence of medium effects on strange quark matter and their consequences for the structural properties of compact stars. In this study, the bag constant, in the MIT bag model equation of state, is reformulated as a…
Non-Gaussian noise transients ("glitches") in gravitational-wave observatories degrade our ability to accurately perform astrophysical inference. We present the analysis pipeline bilby_glitch, which allows for simultaneous Bayesian…
It has been argued that degenerate higher-order scalar-tensor theories and the effective field theory (EFT) of dark energy are endowed with the Vainshtein mechanism, resulting in a screened fifth force in the exterior of a gravitational…
Recently, we demonstrated that while an interstellar mission to the nearest black hole remains highly speculative and extraordinarily challenging, it is not entirely implausible within the coming decades. Given that such a mission would…
We present a concise and explicit analysis of logarithmically corrected black-hole thermodynamics and scalar scattering on the Schwarzschild branch of symmetric teleparallel gravity. Treating the metric and the flat, torsion-free affine…
We discuss the geometry of the two-dimensional sphere. Our perspective focuses on the set of conformal factors that rescale a given metric to a round metric. We find that there exists a unique symmetric and trace-free tensor on the sphere…
We investigate the repetitive Penrose process for neutral particles in a rotating four-dimensional Einstein--Gauss--Bonnet black hole obtained through the modified Newman--Janis algorithm, developing a nonlinear iterative scheme in which…
We revisit the derivation of Morawetz--energy estimates for scalar wave equations in the domain of outer communication of a Kerr spacetime \(\KK(a,m)\). Our goal is to develop robust physical-space methods which are well suited for…
Within Einstein power-Yang-Mills gravity (EPYM), we build a rotating black hole via the Newman-Janis procedure applied to the spherically symmetric static seed, obtaining a Kerr-like metric controlled by the spin \(a\), the magnetic…