General Relativity and Quantum Cosmology
Perturbation theory is an essential tool to model and interpret gravitational dynamics, for example, binary black hole mergers. Therefore it is also crucial to precisely understand its regimes of validity. The collapse of a scalar field…
Analytical solutions encompassing the so-called Hubble tension problem are revisited through the framework of Weyl--Wigner quantum mechanics and discussed in the context of generalized phase-space scenarios of quantum cosmology. After…
The superradiant instability of rotating black holes can generate a significant overdensity of bosonic matter around them, together forming a gravitational atom. This mechanism allows one to probe a large part of the parameter space of…
In general relativity, the motion of a test mass around a rotating black hole is described by Kerr geodesics. Owing to the symmetries of the Kerr spacetime, these geodesics possess four constants of motion, rendering the associated…
The Teukolsky equation possesses discrete symmetries that constrain the properties of black hole perturbations and their quasinormal mode spectrum. In this study, we explore how a class of modifications of the Teukolsky potential can alter…
Kerr black-hole quasinormal modes are usually computed with numerical methods, but analytic approximations remain useful for identifying the physics that controls different parts of the spectrum. In this paper, we ask whether the divergent,…
We consider the necessary and sufficient conditions for the smooth matching of an expanding McVittie spacetime and a spatially flat Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) spacetime across a general hypersurface - that is, a…
Thin-shell wormholes built from effective black hole geometries are sensitive not only to the lapse function but also to the choice of areal radius. We construct a reflection-symmetric thin-shell wormhole from the positive-lapse sector of a…
From April 10, 2024 to November 18, 2025 Advanced Virgo participated in the fourth observing run of the network of gravitational-wave detectors, together with Advanced LIGO and KAGRA. For this observing run Advanced Virgo has completed its…
Motivated by their common condensed-matter inspiration and their shared aim of reconciling MOND-like phenomenology on galactic scales with particle dark matter on larger scales, we investigate the relation between Superfluid Dark Matter…
We propose a reconstructed cosmological model in the framework of $f(Q,T)$ gravity, that provides a unified description of the early- and late-time evolution of the Universe. The model exhibits a non-singular asymmetric bounce, smoothly…
In this article, we use the expression of the Schwarzian derivative to set up differential equations to find answers to three fundamental questions in the context of QFT in curved spacetime, specifically in two dimensions. One of the ways…
The tidal deformability of a compact object is encoded in a single function of frequency, the retarded Green's function relating the induced multipole to the applied tide. Causality, reality, passivity, and the high-frequency conditions…
This paper addresses the important problem of estimating the noise spectral density of next-generation gravitational-wave detectors, such as LISA and the Einstein Telescope (ET), where cross-channel correlations must be accounted for to…
The gravitational waveform generated by the scattering of two nonspinning bodies is computed in the frequency domain in the extreme-mass-ratio limit at the eighth post-Minkowskian (PM) order (i.e., $O(G^8)$, or six-loop) and at the…
The recent gravitational-wave detection GW250114 by the LIGO-Virgo-KAGRA (LVK) Collaboration provides unprecedented precision for testing general relativity (GR) through black hole ringdowns. In this study, we provide the first bounds on…
In this work, we investigate the effect of chaotic orbits on the extreme mass ratio inspiral (EMRI) gravitational wave signals where the central black hole is corrected by quantum conformal anomaly. We utilize the numerical kludge method to…
In general relativity, exact Liouvillian solutions for a static and spherically symmetric spacetime with a perfect fluid and the equation of state $p(r)=w\rho (r)$ are known only for $w=0,-\frac{1}{6}, -\frac{1}{5}, -\frac{1}{3}, -1$. We…
In this work we solve the coupled Einstein-Dirac-Maxwell (EDM) system for static spherically symmetric configurations of two fermions in a singlet spinor state within the $3+1$ formalism of general relativity. We find different families of…
The Laser Interferometer Space Antenna (LISA) launches in less than a decade; it will detect spinning high-mass-ratio binary black hole inspirals annually, alongside other third-generation gravitational wave detectors. High-mass-ratio…