General Relativity and Quantum Cosmology
Persistent discrepancies between early- and late-Universe measurements have made cosmological tensions a major test of the standard $\Lambda$CDM model. We investigate whether an entropic generalized Chaplygin-gas cosmology, describing a…
In these lecture notes for the Les Houches School on Loop Quantum Gravity 2025, which took place in September 2025, we give a pedagogical review of the basics of the spinfoam framework for a quantum gravity path integral. While spin network…
We developed in this work a perturbative technique to compute the deflection angle of light rays in general static and spherically symmetric spacetimes with a homogeneous non-magnetic plasma. The deflection angle is expressed as a power…
We ask when a spinless spherical extended test body in vacuum general relativity moves as its point-particle counterpart. In Newtonian gravity, harmonicity of the external potential gives an all-order cancellation: in source-free regions…
The relativistic precession model (RPM) interprets the twin kilohertz quasi-periodic oscillations (QPOs) as geodesic frequencies of test particles orbiting in the spacetime of X-ray binaries hosting either a neutron star (NS) or a black…
We investigate baryogenesis in the framework of rainbow cosmology employing a complex scalar field with a softly broken global $U(1)$-symmetry. The modified dispersion relation of rainbow cosmology leads to energy-dependent modification to…
We construct numerically two families of static five-dimensional Lorentzian metrics, solutions of vacuum Einstein equations with a negative cosmological constant, one with and one without a black hole region, with a metric at sections of…
We investigate cosmic evolution in generalized Nash's theory of gravity involving the quadratic Ricci invariant $\chi=R_{\mu\nu}R^{\mu\nu}$. The analysis is divided into two complementary branches. First, we study the power-law family…
In this study, black hole solutions are derived within the framework of Einstein gravity, coupled to a $U(1)$ gauge field in the presence of both the Letelier--Alencar \textit{cloud of strings} and the cosmological constant. Subsequently,…
In these notes, we extend a formalism for computing the amplitude of gravitational-waves (GWs) beyond null-geodesic propagation, as may arise in alternative theories of gravity. We derive the wavevector divergence governing the amplitude…
We construct and analyze stationary, axisymmetric vacuum metrics obtained by magnetic Ernst inversion of Kerr-NUT with Manko-Ruiz parameter $C$ and pre-inversion twist constant $\beta$. The transformation lies in the Ehlers orbit; our…
We investigate static, spherically symmetric charged black holes in Einstein gravity coupled to Euler--Heisenberg (EH) nonlinear electrodynamics, including purely electric, purely magnetic, and dyonic configurations. Rather than adopting…
Gravitational-wave (GW) signals from core-collapse supernovae (CCSNe) contain both stochastic and deterministic components. Among these, the High-Frequency Feature (HFF), associated with PNS oscillations, has emerged as a robust observable…
This paper presents a convolutional neural network (CNN) approach to classifying the nuclear equation of state (EOS). As illustrative examples, we use five two-dimensional core-collapse supernova (CCSN) simulations that differ only in their…
We study soliton-black hole phase transitions in asymptotically AdS planar spacetimes sourced by a cloud of strings. In the planar background, the string cloud exhibits a brush-like configuration, where the strings are aligned parallel to…
We find a system of differential equations on an initial data surface whose solutions are in bijection with unit vector fields on the Einstein $\Lambda$-vacuum development that are proportional to a Killing vector. We refer to these…
We investigate static, spherically symmetric black hole solutions in a class of higher-curvature gravitational theories described by a Lagrangian that depends on the Ricci and Kretschmann scalars. The modified Einstein equations contain…
We study the thermodynamic and dynamical properties of static, spherically symmetric BHs in Einstein-Maxwell theory modified by a non-minimal $\ln(R)F^{2}$ coupling. The Hawking temperature follows from the Hamilton-Jacobi form of the…
We develop a local and covariant framework for constraining the evolution of generalized entropy along null horizons, combining classical geometric methods with constraints from quantum field theory. Building on the quantum focusing…
We investigate gravitational lensing by compact objects embedded in anisotropic Bianchi-I cosmologies using directional Jacobi maps within the thin-lens approximation. The formalism is developed for a general diagonal Bianchi-I spacetime…