We are a theoretical gravity group of about twenty researchers (faculty, postdocs and PhD students) working on black holes, neutron stars and gravitational waves, from fundamental theory to the modelling and analysis of real and future data. Our goal is to turn compact objects into laboratories for fundamental physics: to test Einstein's theory in its strongest regime, to probe the nature of black holes and of spacetime singularities, to constrain the behaviour of matter at supranuclear densities, and to search for new particles and dark matter.
We are active members of the Einstein Telescope Collaboration and of the LISA Consortium, where we contribute to the science case, waveform modelling and data-analysis studies. Recent community-wide efforts we helped write include the LISA Definition Study Report (2024), The Science of the Einstein Telescope (2025) and the review Black hole spectroscopy: from theory to experiment (2025). We are also part of the INFN initiative TEONGRAV and of the Amaldi Research Center at Sapienza.
Our research at a glance: topics sized by how many of the group's ~190 papers from 2022 to 2026 mention them.
1. Black-hole spectroscopy and ringdown
After two black holes merge, the remnant "rings down" emitting a set of characteristic frequencies, the quasinormal modes, which depend only on its mass and spin in General Relativity. Measuring them is the cleanest test of the black-hole paradigm. We develop the theory of the ringdown (linear and nonlinear perturbations, excitation coefficients, late-time tails, spectral stability and greybody factors), calibrate ringdown models against numerical-relativity simulations, and design new tests of gravity for current detectors, ET and LISA.
- Graybody factors as stable gravitational-wave observables; Novel ringdown tests of General Relativity with graybody factors
- Excitation coefficients for equatorial inspirals into Kerr black holes; Universality of late-time ringdown tails
- Accuracy of ringdown models calibrated to numerical relativity; Testing gravity with ringdown amplitudes
2. Gravitational-wave modelling and data analysis for ET and LISA
Next-generation detectors will observe signals with unprecedented signal-to-noise ratio, so waveform models and analysis methods must become far more accurate. We model compact-binary inspirals and mergers, extreme-mass-ratio inspirals (EMRIs) for LISA, including self-force and new fundamental fields, and study the systematics that could mimic violations of General Relativity. On the data side we perform parameter-estimation and population studies, forecast the science reach of ET and LISA, and assess detector configurations.
Figure: candidate Einstein Telescope sites and configurations, from arXiv:2610.10669.
- Adiabatic evolution of asymmetric binaries with new fundamental fields; EMRIs as probes of scalar fields around Kerr black holes
- Possible causes of false GR violations in gravitational-wave observations; Systematics in distance and inclination measurements: role of the detector network
- Black-hole formation channels in GWTC-4.0; Impact of site-dependent noise on Einstein Telescope science
3. Neutron stars and the equation of state
Neutron stars probe matter at densities beyond the reach of terrestrial laboratories. Their tidal deformation during a binary inspiral leaves an imprint on the gravitational-wave signal that encodes the equation of state. We compute static, dynamical and nonlinear tidal responses, from effective field theory to waveforms ready for data analysis, study universal relations and magnetized stars, and combine gravitational-wave and electromagnetic observations to constrain nuclear physics.
- Dynamical tidal response of neutron stars: from EFT to waveforms; Nonlinear relativistic tidal response of neutron stars
- New universal relations for magnetized neutron stars; Cosmology and nuclear physics implications of a subsolar GW event
4. The nature of black holes and tests of General Relativity
Are astrophysical black holes really described by the Kerr metric? What replaces the singularity at their centre? We study black-hole mimickers and horizonless compact objects (from string-theory microstates and topological stars to boson stars), regular and non-singular black holes, black holes in theories beyond General Relativity, and their tidal Love numbers, and we work out how observations can tell them apart.
Figure: gravitational lensing by a W-soliton microstate vs a black string, from W-solitons as prototypical black hole microstates.
- Black hole mimickers: from theory to observation; Towards a non-singular paradigm of black hole physics
- Dynamical Love numbers of black holes; Vanishing Love numbers of Kerr-Newman black holes
- Quasinormal modes of black holes in quadratic gravity; Dynamical hair growth in binaries in Einstein-scalar-Gauss-Bonnet gravity
5. Fundamental fields, dark matter and environments
Black holes and neutron stars rarely live in vacuum and can host or interact with new light particles. We study ultralight bosons and superradiant instabilities, boson stars, dark-matter halos, accretion disks and plasmas around compact objects, and how these environments affect gravitational-wave signals. A key question is how to tell environmental effects apart from genuine deviations from General Relativity, and how new fields would show up in the inspiral, merger and ringdown of a binary.
- Quasinormal modes of black holes embedded in halos of matter; Superradiance of charged black holes in dark-matter halos
- Dynamics and GWs of boson-star mergers; Tidal deformability of black holes surrounded by accretion disks
6. Primordial black holes and the early Universe
Black holes formed in the early Universe could be part of the dark matter and would leave distinct signatures in gravitational-wave catalogues, in the stochastic background and in pulsar timing arrays. We study their formation, abundance and clustering, and develop observational tests, including subsolar-mass events and tidal effects, as well as broader cosmological applications.
- Constraints on primordial black holes from LVK O3 events; Curbing PBHs with PTAs
- Can we identify primordial black holes? Tidal tests for subsolar-mass events; How well do we know scalar-induced gravitational waves?
The full list of our papers is on the Publications page; codes and data are in our GIT repository.