We present an unmodelled, targeted search for generic gravitational wave transients associated with high-energy neutrinos detected by the IceCube Neutrino Observatory during the third observing run of Advanced LIGO, Advanced Virgo, and KAGRA. Our search is sensitive to gravitational wave signals weaker than those reported in real time or in the gravitional wave transient catalog, and can thus...
We investigate observable signatures of strong phase transitions in neutron star cores through two complementary approaches. First, we analyze the oscillation spectrum of isolated neutron stars hosting a sharp density discontinuity, comparing full general relativistic simulations with results from the Cowling approximation. This reveals the behavior of interface modes that could become tidally...
The Stochastic Gravitational Wave Background (SGWB) from cosmic superstrings offers one of the few known possibilities to test String Theory within current experimental reach. However, in order to be compatible with the existing constraints, the tension of a cosmic superstring network is required to lie several orders of magnitude below the Planck scale. This is naturally realized in string...
Gravitational lensing of gravitational waves is expected to be observed in
current and future detectors. In view of the growing number of detections, computation-
ally light pipelines are needed. Detection pipelines used in past LIGO-Virgo-KAGRA
searches for strong lensing require parameter estimation to be performed on the gravi-
tational wave signal or are machine learning based....
Rotating stars with non-uniform deformations are a very important source of continuous gravitational waves, but representing the radiative part of their gravitational field analytically is mostly limited to using the post-Newtonian method (e.g. Blanchet-Damour 1990), which decomposes the zone of the external gravitational field into a ‘near’ (pseudo-stationary) zone and an 'intermediate'...
When a gravitational wave signal encounters a massive object, such as a galaxy or galaxy cluster, it undergoes strong gravitational lensing, producing multiple copies of the original signal. These strongly lensed signals exhibit identical waveform morphology in the frequency domain, allowing analysis without the need for complex lens models. However, stellar fields and dark matter...
General relativity predicts that a signal passing a massive object will be
deflected by the spacetime curvature induced by that object. This process is
known as gravitational lensing and bears some similarities to e.g. the lensing
of light through glass. Gravitational lensing of light was first observed over
a century ago and was a fundamental test of general relativity. Since then,...
The observations of the gravitational wave signal GW170817 from a binary neutron star merger have marked the beginning of a new era in astrophysics. Such events offer unique opportunities to probe the properties of matter under conditions so extreme that they cannot be experimentally reproduced in terrestrial laboratories. However, modeling these events remains a major challenge because many...
We have been detecting gravitational wave (GW) signals from coalescing compact binary systems for nearly a decade. The morphology of these signals can be shaped by a variety of intrinsic and extrinsic parameters. With 90 GW events reported up to the end of the O3 run and 128 already uncovered in the ongoing O4 run, the rapidly growing catalog presents new challenges. Morphological similarities...
Eccentric binary compact mergers are key targets for current and future gravitational wave observatories. In the small mass ratio expansion, post-adiabatic inspirals have been modeled up to the separatrix, where first-principles modeling currently ends. However, a complete waveform model for eccentric binaries requires an accurate description of the plunge and the transition from the inspiral...
Gravitational-wave (GW) data-analysis methods for compact binary
coalescences (CBCs) are generally divided into two categories. On the
one hand, there are modelled techniques, in which a detected signal
is compared to a theoretical model of the CBC source. On the other
hand, unmodelled approaches attempt to reconstruct the signal
without relying on a specific model by using a...
Gravitational-wave (GW) astronomy has revolutionized our understanding of the universe, but the precision of its discoveries hinges on the accurate calibration of GW detectors. In this talk, we present a novel Bayesian null-stream method for self-calibration of closed-geometry GW detector networks, such as the Einstein Telescope (ET) and LISA. Unlike traditional approaches that rely on...
Extreme mass-ratio inspirals (EMRIs), consisting of a stellar-mass compact object spiraling into a massive black hole, are key targets for space observatories like the recently adopted LISA, TianQin, and Taiji. Together with self-force effects, the smaller companion spin is one of the crucial post-adiabatic terms needed for accurate waveform templates. This work presents the adiabatic,...
The detection of gravitational waves (GWs) from compact binary mergers has become routine. However, stochastic and non-stationary signals, such as those expected from core-collapse supernovae (CCSNe), remain elusive. These complex, burst-like signals pose a significant challenge for traditional Bayesian inference methods, which can be computationally expensive and struggle with intractable...
Direct detections of gravitational waves offer a unique opportunity to test gravity in the highly dynamical and strong field regime. Current tests are typically performed assuming signals from quasi-circular binaries. However, the complex waveform morphology induced by orbital eccentricity can enhance our ability to probe gravity with greater precision. A recent analysis of the neutron...
Extreme Mass-Ratio Inspirals (EMRIs) are among the targeted gravitational wave sources for LISA, promising valuable insights into fundamental physics and astrophysics. Preparing for the complex task of EMRI data analysis requires realistic, synthetic datasets. This talk presents the EMRIs for the Mojito light dataset, the upcoming Mock Data Challenge by the LISA DDPC designed for LISA data...
We present the first numerical simulations of binary black holes and binary neutron star mergers in scalar–Gauss–Bonnet gravity performed in the modified puncture gauge, which is a well-motivated theory from an effective field theory point of view. Implemented within both GRChombo and MHDuet codes, our modified formulation enables stable evolution through merger and post-merger phases. These...
Bayesian inference, widely used in gravitational-wave parameter estimation, crucially depends on the choice of priors. Yet, for mergers involving neutron stars, priors are often chosen in an agnostic way, leaving valuable information from nuclear physics and independent observations of neutron stars unused. We propose to encode information on neutron star physics into data-driven prior...
To leverage the full potential of next-generation gravitational wave observatories, such as the Einstein Telescope (in Europe) and LISA (in space), we will need to improve the efficiency of numerical relativity (NR) simulations in terms of computational speed and accuracy. In this talk, we will introduce probabilistic numerics as a promising new approach to gain control over uncertainties in...
Gravitational wave (GW) detectors routinely encounter transient noise bursts, known as glitches, which are caused by either instrumental or environmental factors. Due to their high occurrence rate, glitches can overlap with GW signals, as in the notable case of GW170817, the first detection of a binary neutron star merger. Accurate reconstruction and subtraction of these glitches is a...
Boson stars are compact objects composed of fundamental fields
arising in theories beyond the standard model (SM) of particle physics.
From dark-matter halos to ultracompact objects with light rings,
they have acquired an important role in gravitational-wave driven
searches for physics beyond the "GR+SM" paradigm. In this talk
we present an overview of the modeling of boson-star...
As gravitational wave detectors become more sensitive, they will detect so many sources that individual events blend together to form a stochastic Gravitational Wave Background (GWB). Detecting anisotropies in this background could provide valuable insights into various cosmological and astrophysical properties. Given the strong expectation that LISA will detect the astrophysical GWB created...
The current detection of gravitational waves (GW) in the audible range involves the construction of detectors specifically dedicated, covering a wide spectrum but requiring costly construction. Future detectors are expected to cover the mHz frequency, while the pulsar signal based detection covers the nHz range, leaving the μHz regime largely unexplored. Thanks to their onboard atomic clocks...
In this work, we develop a Neural Likelihood Estimator and apply it to analyse real gravitational-wave (GW) data for the first time. We assess the usability of neural likelihood for GW parameter estimation and report the parameter space where neural likelihood performs as a robust estimator to output posterior probability distributions using modest computational resources. In addition, we...
Neutrinos play a crucial role in the explosion mechanism of core-collapse supernovae. Including them in simulations requires to solve the Boltzmann equation, which is very expensive to solve because of its higher dimensionality. Most simulations therefore rely on approximations to that equation that are more affordable. The effect of these approximations on the evolution of the system and on...
It is currently uncertain how many white dwarf (WD) binaries LISA will be able to detect in the globular clusters (GCs) around the Milky Way, with predictions ranging from zero to dozens. However, there is another question: if there is a WD binary in a GC, would LISA actually be able to resolve it well enough in terms of sky location and distance that the binary could be distinguished from...
The future space-based gravitational-wave observatory LISA will detect massive black hole binaries (MBHBs) with signal-to-noise ratios (SNRs) reaching thousands. Such precision demands accurate modeling of the detector response. Current formulations neglect spacecraft motion during light travel time, omitting velocity-dependent terms of order $v/c \sim 10^{-4}$. We derive these corrections and...
My PhD project aims to overcome a fundamental limitation in gravitational wave detectors and optical clocks:
coating Brownian thermal noise (CBTN), which arises from microscopic vibrations in mirror coatings. The
proposed solution is to reshape laser beams into exotic optical modes—specifically Hermite-Gaussian (HG)
modes—which distribute light more broadly across mirror surfaces, reducing...
Ultracompact black hole mimickers formed through gravitational collapse under reasonable assumptions obtain light rings in pairs, where one is unstable and the other one is not. Stable light rings are believed to be a potential source for dynamical instability due to the trapping of massless perturbations, as the decay of these modes is relatively slow.
We have performed fully nonlinear...
With the upcoming space based gravitational wave detector LISA approaching, many open questions still remain. One of the golden observables for the mission will be Extreme Mass Ratio Inspirals (EMRI); a stellar mass Black Hole (BH) gradually spiralling into its supermassive companion, emitting gravitational waves containing a wealth of information about the BH environment. An exciting...
Three-dimensional simulations can provide the most accurate modelling of the merger between stars, this includes the precise computation of their gravitational-wave signals. With the state-of-the-art 3DMHD code AREPO we can study stellar mergers at many different scales, ranging from giant stars to neutron stars, releasing GWs all over the frequency spectrum.
With these simulations we can...
As gravitational wave detectors become increasingly sensitive, the number of observed sources continues to rise. Unlocking the full scientific potential of these detections depends on robust and efficient data analysis, making gravitational wave data analysis a rapidly evolving and essential field. In this talk, we introduce the core principles of gravitational wave data analysis, emphasizing...
The impetus for wide-field searches for counterparts of explosive transients including binary neutron-star mergers, supernovae, and tidal disruption events has never been higher. The ongoing operations with the LIGO-Virgo network of gravitational wave detectors in the 4th observing period continues to offer challenges for optical observers, primarily due to the poor (~100 deg^2) localisation...
