A5006603438- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Gaussian Processes and Bayesian Inference
- Dark Matter and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Computational Physics and Python Applications
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Superconducting and THz Device Technology
- Geometric and Algebraic Topology
- Advanced Differential Geometry Research
- Spectroscopy and Chemometric Analyses
- History and Developments in Astronomy
- Quantum Chromodynamics and Particle Interactions
- Scientific Research and Discoveries
- Information Systems and Technology Applications
- Advanced Data Processing Techniques
- Markov Chains and Monte Carlo Methods
- Astrophysics and Cosmic Phenomena
- Cybersecurity and Information Systems
University of Padua
2023
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2023
RWTH Aachen University
2019-2023
Université Libre de Bruxelles
2022-2023
University of Sussex
2017-2021
UK Astronomy Technology Centre
2017
University of Edinburgh
2017
Leiden University
2014
Technical University of Munich
2013
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 Stellar-mass black-hole binaries are the most numerous gravitational-wave sources observed to date. Their properties make them suitable for observation both by ground- and space-based detectors. Starting from synthetic catalogues constructed based on observational constraints ground-based detectors, we explore detection rates characteristic parameters of stellar-mass observable LISA during their inspiral, using signal-to-noise ratio thresholds as a criterion. We find that only...
We present Cobaya, a general-purpose Bayesian analysis code aimed at models with complex internal interdependencies. Without the need for specific by user, interdependencies between different stages of model pipeline are exploited sampling efficiency: intermediate results automatically cached, and parameters grouped in blocks according to their dependencies optimally sorted, taking into account individual computational costs, so as minimize cost variation during sampling, thanks novel...
Abstract We use the latest constraints on population of stellar origin binary black holes (SOBBH) from LIGO/Virgo/KAGRA (LVK) observations, to estimate stochastic gravitational wave background (SGWB) they generate in frequency band LISA. In order account for faint and distant binaries, which contribute most SGWB, we extend merger rate at high redshift assuming that it tracks star formation rate. adopt different methods compute SGWB signal: perform an analytical evaluation, Monte Carlo sums...
We continue the study of mild transient reductions in speed sound adiabatic mode during inflation, their effect on primordial power spectrum and bispectrum, detectability cosmic microwave background (CMB). focus regime moderately sharp uninterrupted slow-roll a theoretically well motivated self-consistent that admits an effective single-field description. The signatures bispectrum were previously computed using Fourier transform (SRFT) approximation, here we compare it with generalized slow...
The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate universe, and understand stochastic gravitational-wave backgrounds their implications for early universe particle physics, from MeV Planck scale. However, range potential applications gravitational wave observations extends well beyond these objectives. This publication presents a summary state art in LISA cosmology, theory methods, identifies new opportunities use...
The first year of observations by the Planck satellite mission shows that cosmic microwave background fluctuations are consistent with Gaussian statistics in primordial perturbations, a key prediction simplest models inflation. However, there hints anomalies power spectrum and bispectrum. We check for possibility some these anomalous features have common physical origin transient reduction inflaton speed sound. do this exploiting predicted correlations between Our results suggest current...
Abstract A gravitational wave background from a first order phase transition in the early universe may be observable at millihertz (GW) detectors such as Laser Interferometer Space Antenna (LISA). In this paper we introduce and test method for investigating LISA's sensitivity to waves using parametrised templates an approximation more complete physical model. The motivation developing is provide less computationally intensive way perform Markov Chain Monte Carlo (MCMC) inference on...
Abstract We present the GPry algorithm for fast Bayesian inference of general (non-Gaussian) posteriors with a moderate number parameters. does not need any pre-training, special hardware such as GPUs, and is intended drop-in replacement traditional Monte Carlo methods inference. Our based on generating Gaussian Process surrogate model log-posterior, aided by Support Vector Machine classifier that excludes extreme or non-finite values. An active learning scheme allows us to reduce required...
We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N>=1 supersymmetry in 4D for the heterotic string. Our strategy is based on crystallographic space groups six dimensions. find total 520 inequivalent orbifolds, 162 them with Abelian point such as Z_3, Z_4, Z_6-I etc. and 358 non-Abelian S_3, D_4, A_4 also briefly explore properties some N=1, i.e. specify Hodge numbers comment possible mechanisms (local or non-local) gauge symmetry breaking.
We present a data analysis methodology for model-independent reconstruction of the spectral shape stochastic gravitational wave background with LISA. improve previously proposed algorithm that relied on single Time-Delay-Interferometry (TDI) channel by including complete set TDI channels. As in earlier work, we assume an idealized equilateral configuration. test improved number case studies, presence two different astrophysical foreground signals. find additional channels helps ways: it...
Abstract In modern analysis pipelines, Einstein-Boltzmann Solvers (EBSs) are an invaluable tool for obtaining CMB and matter power spectra. To significantly accelerate the computation of these observables, CosmicNet strategy is to replace usual bottleneck EBS, which integration a system differential equations linear cosmological perturbations, by trained neural networks. This offers several advantages compared direct emulation final including very small networks that easy train in...
We study the stochastic distribution of spectator fields predicted in different slow-roll inflation backgrounds. Spectator have a negligible energy density during but may play an important dynamical role later, even giving rise to primordial perturbations within our observational horizon today. During de-Sitter expansion there is equilibrium solution for field which often used estimate inflation. However slow roll only requires that Hubble rate varies slowly compared time, while time taken...
Inspired by the study of mild transient reductions in speed sound adiabatic mode during inflation, we search for a primordial localized feature imprinted cosmic microwave background and large-scale structure formation observables. We find some common oscillatory patterns both Planck CMB temperature-temperature power spectrum WiggleZ galaxy spectrum. By performing independent searches with these two data sets, coincidence most significant previously found Ach\'ucarro et al. 2013 using only...
Einstein-Boltzmann Solvers (EBSs) are run on a massive scale by the cosmology community when fitting cosmological models to data. We present new concept for speeding up such codes with neural networks. The originality of our approach stems from not substituting whole EBS machine learning algorithm, but only its most problematic and least parallelizable step: integration perturbation equations over time. This offers two significant advantages: task depends subset parameters, it is blind...
Simple models of single-field inflation in the very early universe can generate observed amplitude and scale dependence primordial density perturbation, but with multiple fields provide an equally good fit to current data. We show how future observations will be able distinguish between currently favoured models. If a curvaton field generates perturbations after inflation, we total duration measured.
We update the search for features, due to transient reductions in inflaton's speed of sound, Cosmic Microwave Background (CMB) angular power spectrum using Planck 2018 temperature, polarization and lensing data. develop a new methodology test more flexible templates reconstruct reduction sound based on Gaussian Processes. formally derive dynamical prior shape \textit{maximum-entropy} approach ensure physical conditions model are satisfied. The posterior allows one or consecutive reductions,...
We update the search for features in Cosmic Microwave Background (CMB) power spectrum due to transient reductions speed of sound, using Planck 2015 CMB temperature and polarisation data. enlarge parameter space much higher oscillatory frequencies feature, define a robust prior independent ansatz reduction, guaranteed reproduce assumptions theoretical model exhaustive regime which feature is easily distinguishable from baseline cosmology. find fit $\ell\approx20$--$40$ minus/plus structure TT...
We use the latest constraints on population of stellar origin binary black holes (SOBBH) from LIGO/Virgo/KAGRA (LVK) observations, to estimate stochastic gravitational wave background (SGWB) they generate in frequency band LISA. account for faint and distant binaries, which contribute most SGWB, by extending merger rate at high redshift assuming it tracks star formation rate. adopt different methods compute SGWB signal: an analytical evaluation, Monte Carlo sums over SOBBH realisations, a...
Stellar-mass black-hole binaries are the most numerous gravitational-wave sources observed to date. Their properties make them suitable for observation both by ground- and space-based detectors. Starting from synthetic catalogues constructed based on observational constraints ground-based detectors, we explore detection rates characteristic parameters of stellar-mass observable LISA during their inspiral, using signal-to-noise ratio thresholds as a criterion. We find that only handful these...
Bayesian inference remains one of the most important tool-kits for any scientist, but increasingly expensive likelihood functions are required ever-more complex experiments, raising cost generating a Monte Carlo sample posterior. Recent attention has been directed towards use emulators posterior based on Gaussian Process (GP) regression combined with active sampling to achieve comparable precision far fewer costly evaluations. Key this approach is batched acquisition proposals, so that true...
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 noise...
HMCode bug fix and speed up (thanks Alex Mead) Refactoring in equations.f90 so all scalar source outputs now computed derivs function; support for custom functions (as used by python camb.symbolic module) Python CAMB: Added module using sympy, to get equations, convert between gauges, produce compile CAMB code from analytic results different gauges. See the demo notebook demonstrating how use this, set sources, plot perturbation evolution calculate angular power spectra of things. Add...