General Relativity and Quantum Cosmology
We investigate rotational properties and universal relations of slowly rotating Bose-Einstein condensate dark stars in the context of General Relativity, both at the mean-field level and when the leading beyond-mean-field Lee-Huang-Yang…
Modified black-hole entropies can induce effective spacetime geometries and thereby provide a thermodynamic route for investigating thin-shell wormholes. In this work, we construct symmetric cut-and-paste wormholes from the generic entropic…
Motivated by the growing recent interest in black hole solutions immersed in astrophysical dark matter environments, we construct an exact static, spherically symmetric black hole solution sourced by a Dehnen $\left(2,3,0\right)$ dark…
Neutron stars and related compact objects are unique laboratories for probing matter at supranuclear densities and gravity in the strong-field regime. In this thesis, we investigate the hydrostatic equilibrium of compact stars in different…
Pulsar timing array data analysis is computationally expensive, limiting the complexity of models which can be studied. As pulsar timing datasets and their respective models grow in size and sophistication, faster and scalable inference…
Einstein's equations of general relativity are one of the most complicated set of equations in all of physics and, for all but idealized physical settings, can only be solved by numerical methods on high-performance computing systems.…
We herein study both the Joule-Thomson (JT) expansion process and the geodesic properties of a charged anti-de Sitter (AdS) black hole arising in modified gravity with nonlinear electrodynamic (NLED) sources. Our thermodynamic study reveals…
Recent studies have identified a new component in black-hole ringdown from merging binaries, termed the \emph{direct wave}. This component was argued to be tied to the dynamical source evolution near the black-hole horizon, and thus to…
We construct Hilbert-space isomorphisms identifying the spaces of radiation fields on the event horizon and null infinity that are induced by the forward scattering map on the Schwarzschild exterior for fixed spherical harmonic mode…
In this paper, the weak-field behavior of linearized Horndeski theory is studied, with emphasis on the role of a scalar potential with a nonvanishing minimum. In this regime, the minimum of the potential acts as an effective source of…
A key question in early universe cosmology is whether inflation can be successfully seeded by a generic, localised fluctuation in the inflaton field that probes the inflationary part of the potential. Past simulations have mainly considered…
In the present work, we explore an observationally constrained cosmological model in the framework of $f(Q,\mathcal{L}_{m})$ gravity, where $Q$ denotes the non-metricity scalar and $\mathcal{L}_{m}$ represents the matter Lagrangian density.…
In this study, we investigate the polarized images of non-topological soliton Bardeen boson stars by solving the coupled Einstein nonlinear electrodynamics complex scalar field equations, based on the thin accretion disk model surrounding…
The recent ACT DR6 has shifted the preferred value of the scalar spectral index upward so that many well-established inflationary models have been disfavoured, including the Starobinsky potential. Despite this, the Starobinsky potential…
We investigate the stochastic Ricci flow of spherically symmetric perturbations of the Schwarzschild--Anti de Sitter black-hole metric. Elaborating on the Ricci-flow analysis of Headrick and Wiseman, we include a negative cosmological…
We investigate quasinormal modes of the graviscalar sector in a five-dimensional thick brane model in Rastall gravity. By considering a specific flat brane solution supported by a canonical scalar field, we derive a master equation and…
Numerical relativity (NR), solving Einstein equation numerically, plays an important role in source modelling for gravitational wave astronomy. Traditional methods for NR including finite difference method, spectral method and finite…
We investigate whether weak near-zone magnetic fields can leave observable imprints on extreme-mass-ratio inspiral (EMRI) waveforms. The central massive black hole is modeled by the magnetized Schwarzschild, or Ernst, solution, and the…
We introduce the notion of a well-conditioned embedding of a causal set into a Lorentzian manifold and prove that if a causal set admits well-conditioned embeddings into two manifolds, then their interiors are related by an…
General relativity (GR) is currently the best description of the gravitational interaction at our disposal and is one of the foundations of the concordance cosmological model. For as much as we know that GR is not the final theory of…