A5024926912- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Noncommutative and Quantum Gravity Theories
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Relativity and Gravitational Theory
- Astrophysical Phenomena and Observations
- Advanced Differential Geometry Research
- Quantum Electrodynamics and Casimir Effect
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Computational Physics and Python Applications
- Atomic and Subatomic Physics Research
- Astrophysics and Cosmic Phenomena
- Stochastic processes and financial applications
- Adaptive optics and wavefront sensing
- Advanced Mathematical Theories and Applications
- Scientific Research and Discoveries
- Complex Systems and Time Series Analysis
- Statistical and numerical algorithms
Swansea University
2016-2025
University of Bologna
2023-2025
Istituto Nazionale di Fisica Nucleare, Sezione di Bologna
2023-2025
Osservatorio astronomico di Bologna
2023-2024
University of Bern
2018
University of Stavanger
2018
Institute for High Energy Physics
2018
Universitat Autònoma de Barcelona
2018
Universidad de Granada
2018
École Polytechnique Fédérale de Lausanne
2018
We investigate the potential for LISA space-based interferometer to detect stochastic gravitational wave background produced from different mechanisms during inflation. Focusing on well-motivated scenarios, we study resulting contributions particle production inflation, inflationary spectator fields with varying speed of sound, effective field theories inflation specific patterns symmetry breaking and models leading formation primordial black holes. The projected sensitivities are used in a...
We present all scalar-tensor Lagrangians that are cubic in second derivatives of a scalar field, and degenerate, hence avoiding Ostrogradsky instabilities. Thanks to the existence constraints, they propagate no more than three degrees freedom, despite having higher order equations motion. also determine viable combinations previously identified quadratic degenerate newly established ones. Finally, we study whether new theories connected known such as Horndeski beyond Horndeski, through...
We study new consistent scalar-tensor theories of gravity recently introduced by Langlois and Noui with potentially interesting cosmological applications. derive the conditions for existence a primary constraint that prevents propagation an additional dangerous mode associated higher order equations motion. then classify most general, are at quadratic in second derivatives scalar field. In addition, we investigate possible connection between these (beyond) Horndeski through conformal...
We present a set of tools to assess the capabilities LISA detect and reconstruct spectral shape amplitude stochastic gravitational wave background (SGWB) . first provide power-law sensitivity curve binned curves, based on latest updates design. These curves are useful make qualitative assessment detection reconstruction prospects SGWB For quantitative with arbitrary power spectrum shape, we propose novel data analysis technique: by means an automatized adaptive procedure, conveniently split...
Modifications of General Relativity leave their imprint both on the cosmic expansion history through a non-trivial dark energy equation state, and evolution cosmological perturbations in scalar tensor sectors. In particular, modification sector gives rise to notion gravitational-wave (GW) luminosity distance, different from standard electromagnetic that can be studied with sirens at GW detectors such as LISA or third-generation ground based experiments. We discuss predictions for modified...
We identify the effective field theory describing physics of super-Hubble scales and show it to be a special case class theories appropriate open systems. Open systems are those that allow information exchanged between degrees freedom interest integrated out, such as would for particles moving through fluid. Strictly speaking they cannot in general described by an lagrangian; rather 'low-energy' limit is instead Lindblad equation time-evolution density matrix slow freedom. derive relevant...
We review conceptual aspects of inflationary scenarios able to produce primordial black holes, by amplifying the size curvature fluctuations level required for triggering hole formation. identify general mechanisms do so, both single and multiple field inflation. In inflation, spectrum is enhanced pronounced gradients background quantities controlling cosmological dynamics, which can induce brief phases non--slow-roll evolution. amplification occurs through appropriate couplings with...
Abstract We investigate the sensitivity of Laser Interferometer Space Antenna (LISA) to anisotropies Stochastic Gravitational Wave Background (SGWB). first discuss main astrophysical and cosmological sources SGWB which are characterized by in GW energy density, we build a Signal-to-Noise estimator quantify LISA different multipoles. then perform Fisher matrix analysis prospects detectability anisotropic features with for individual multipoles, focusing on power-law frequency profile. compute...
Abstract Dynamical dark energy has gained renewed interest due to recent theoretical and observational developments. In the present paper, we focus on a string-motivated set-up, perform detailed cosmological analysis of exponential quintessence with potential V = 0 e λϕ -, allowing for non-zero spatial curvature. We first gain some physical intuition into full evolution such scenario by analysing corresponding dynamical system. Then, test model using combination Planck CMB data, DESI BAO as...
We study spherically symmetric solutions in a covariant massive gravity model, which is candidate for ghost-free non-linear completion of the Fierz-Pauli theory. There branch that exhibits Vainshtein mechanism, recovering General Relativity below radius given by $(r_g m^2)^{1/3}$, where $m$ graviton mass and $r_g$ Schwarzschild matter source. Another exact exists, corresponding to Schwarzschild-de Sitter spacetimes curvature scale de space proportional squared graviton.
We investigate strong coupling effects in a covariant massive gravity model, which is candidate for ghost free non-linear completion of Fierz-Pauli. analyse the conditions to recover general relativity via Vainshtein mechanism weak field limit, and find three main cases depending on choice parameters. In first case, potential such that all non-linearities disappear vDVZ discontinuity cannot be avoided. second allows within macroscopic radius from source. last scalar graviton completely...
We discuss a consistent theory for self-interacting vector field, breaking an Abelian symmetry in such way to obtain interesting behavior its longitudinal polarization. In appropriate decoupling limit, the dynamics of mode is controlled by Galileon interactions. The full away from limit does not propagate ghost modes, and can be investigated regimes where non-linearities become important. When coupled gravity, this provides candidate dark energy, since it admits de Sitter cosmological...
We consider mechanisms for producing a significant population of primordial black holes (PBHs) within string inspired single field models inflation. The production PBHs requires large amplification in the power spectrum curvature perturbations between scales associated with CMB and PBH formation. In principle, this can be achieved by temporarily breaking slow-roll conditions during work, we identify two setups that realise process. axion inflation, subleading non-perturbative effects...
Starting from the general Horndeski action, we derive most effective theory for scalar perturbations around flat space that allows us to screen fifth forces via Vainshtein mechanism. The is described by a generalization of Galileon Lagrangian, which use study stability spherically symmetric configurations exhibiting effect. In particular, discuss phenomenological consequences scalar-tensor coupling absent in standard Lagrangian. This controls superluminality and fluctuations inside radius...
Though simple inflationary models describe the CMB well, their corrections are often plagued by infrared effects that obstruct a reliable calculation of late-time behaviour. We adapt to cosmology tools designed address similar issues in other physical systems with goal making predictions. The main such tool is Open EFTs which reduce case Stochastic Inflation plus calculable corrections. apply this model complicated enough have dangerous IR behaviour yet allow inference find standard...
The stochastic gravitational wave background (SGWB) is expected to be a key observable for (GW) interferometry. Its detection will open new window early Universe cosmology and the astrophysics of compact objects. Using Boltzmann approach, we study angular anisotropies GW energy density, which an important tool disentangle different cosmological astrophysical contributions SGWB. Anisotropies in are imprinted both at its production by propagation through large-scale scalar tensor perturbations...
Determining the most general, consistent scalar tensor theory of gravity is important for building models inflation and dark energy. In this work we investigate number degrees freedom present in beyond Horndeski. We discuss how to construct from extrinsic curvature constant field hypersurface, find a simple expression action which guarantees existence primary constraint necessary avoid Ostrogradsky instability. Our analysis completely gauge-invariant. However confirm that, mixing together...
A future detection of the stochastic gravitational wave background (SGWB) with (GW) experiments is expected to open a new window on early universe cosmology and astrophysics compact objects. In this paper we study SGWB anisotropies, that can offer tools discriminate between different sources GWs. particular, cosmological inherits its anisotropies both (i) at production (ii) during propagation through our perturbed universe. Concerning (i), show it typically leads order one dependence...
The possibility that primordial black holes constitute a fraction of dark matter motivates detailed study possible mechanisms for their production. Black can form by the collapse curvature fluctuations, if amplitude small scale spectrum gets amplified several orders magnitude with respect to CMB scales. Such enhancement example occur in single-field inflation exhibit transient non-attractor phase: this work, we make investigation shape scenario. We use an analytical approach based on...
In order to produce primordial black holes, or enhance the spectrum of gravitational waves at interferometer scales, cosmological inflation should include brief periods nonattractor evolution, with departures from slow-roll conditions. To better understand these systems we develop a model independent, analytic approach study fluctuations in single field inflationary models short violation. We Taylor expand equations for quantity parametrizing duration violation, and find solutions leading...
Single field models of inflation capable producing primordial black holes usually require a significant departure from the standard, perturbative slow-roll regime. In fact, in many these scenarios, size parameter $|\ensuremath{\eta}|$ becomes larger than one during short phase inflationary evolution. order to develop an analytical control on systems, we explore limit large, and promote $1/|\ensuremath{\eta}|$ small quantity be used for expansions. Formulas simplify, obtain analytic...
Abstract Gravitational wave (GW) backgrounds of cosmological origin are expected to be nearly isotropic, with small anisotropies resembling those the cosmic microwave background. We analyse case a scalar-induced GW background and clarify in process relation between two different approaches calculating anisotropies. focus on scenarios sourced by significantly peaked scalar spectrum, which frequently considered context primordial black holes production. show that resulting characterised...