What: phenomgrav astrophysics seminar

When: Jan 8th, 2026, 15:00-16:00 CET

Where: Building C - Room 248  (first floor)

Speaker: Dr. Mauro Pieroni, Instituto de Estructura de la Materia (IEM-CSIC), Madrid

Title: Simulation-Based Inference for Stochastic Gravitational Wave Background Reconstruction

Abstract: Simulation-Based Inference (SBI), also known as likelihood-free inference, is an alternative to traditional Monte Carlo techniques for performing Bayesian inference. SBI typically relies on machine learning methods to approximate the posterior distribution of model parameters given observed data. In recent years, SBI has been applied to a wide range of problems in physics, including gravitational wave (GW) astronomy. In this talk, I will review the basic principles of SBI and discuss its application to the detection and characterization of stochastic gravitational wave backgrounds with LISA.

What: astrophysics seminar

When: Nov 27th, 2025, 15:00-16:00 CET

Where: Building C - Room 248  (first floor)

Speaker: Dr. Annalisa Pillepich -  Max-Planck-Institut für Astronomie (MPIA)

Title: Universe(s) in a box: simulating galaxies to connect theory and observations

Abstract: Over the past decade, cosmological simulations have become a cornerstone of theoretical astrophysics — powerful “universes in a box” that connect fundamental physics and our understanding of the Universe as a whole to the galaxies and structures observed across cosmic time. These simulations combine the laws of gravity, magneto-hydrodynamics, and gas and atomic physics with models for star formation, supernova explosions, and feedback from supermassive black holes, enabling direct links between physical theory and astronomical observations. I will discuss the IllustrisTNG project, a suite of large-volume simulations that has become a benchmark for modeling the formation and evolution of galaxies, and present some of its successors, such as TNG-Cluster, which follows the growth of hundreds of massive galaxy clusters. I will highlight a few key discoveries enabled by these simulations, particularly the tight interplay between feedback from the innermost regions of galaxies and the thermodynamical, chemical, and kinematic properties of the gas in their surroundings — from the circumgalactic medium to the hot plasma of galaxy clusters. Finally, I will discuss how new techniques -- including forward modeling, machine learning, and our new project of sub-parsec resolution simulations -- are opening a path toward connecting the physics of individual stars and the interstellar medium to the formation of galaxies in the full cosmological context, as well as the use of galaxies, groups, and clusters as cosmological probes.

What: phenomgrav astrophysics seminar

When: July 7th, 2025, 15:00-16:00 CEST

Where: Building C - Room 131, ground floor

Speaker: Dr. Stefano Rinaldi - Institut für Theoretische Astrophysik, Universität Heidelberg

Title: Expect the unexpected – Inference of the black hole distribution using both parametric and non-parametric methods

Abstract: Black holes are the remnants of the most massive of stars, and characterising their population using gravitational wave (GW) observations can help us understand the astrophysical processes governing the life and death of stars. In this picture, non-parametric methods represent an excellent agnostic tool to describe our observations and guide the development of new astrophysical models; on the downside, they lack the interpretability carried by physically informed models. During this talk, I will present two approaches designed to combine the strengths of parametric and non-parametric methods: 1) the concept of augmented mixture model – a weighted superposition of astrophysical and non-parametric models capable of accounting for unforeseen features in the black hole spectrum - and 2) a procedure that first performs a non-parametric (data-driven) reconstruction of the underlying distribution, and then remaps these results onto a posterior for the parameters of an informed model.

What: phenomgrav astrophysics seminar

When: June 10th, 2025, 15:00-16:00 CEST

Where: Building C - Room 248, first floor

Speaker: Dr. Alice Garoffolo - UPenn University

Title: Gravitational waves in wave optics

Abstract: An intriguing aspect of gravitational wave lensing is the emergence wave-effects: interference and diffraction patterns in the waveforms due to finite size effects, occurring when the wave’s wavelength is comparable to the Schwarzschild radius of the lens. These phenomena are particularly interesting because they induce frequency dependent modifications in the waveforms, allowing for a better lens’ parameter estimation, especially if the lensing event has an electromagnetic counterpart in the opposite optical regime.Despite the promising potential of wave-optics effects, our current theoretical tools, based on the diffraction integral, rely on two main assumptions that limit their effectiveness: the eikonal and paraxial approximations on one hand, and the neglect of spin effects on the other. In this talk I will present our new formalism, based on the established proper time technique in field theory, illustrating its robustness as the generalization of the diffraction integral, going beyond all of the limitations mentioned.

What: phenomgrav astrophysics seminar

When: June 5th, 2025, 10:00-11:00 CET

Where: Building C - Room 248, first floor

Speaker: Farid Thaalba - University of Nottingham

Title: Predictivity in Extensions of General Relativity and the Standard Model

Abstract: Extensions of General Relativity often suffer from an ill-posed initial value problem, severely limiting their predictive power. In this work, we tackle this challenge through a numerical investigation of scalar-Gauss-Bonnet gravity. We demonstrate that, within the effective field theory paradigm, the careful inclusion of specific interactions is crucial for overcoming this issue, offering new insights that could significantly enhance the predictivity of extensions of General Relativity.

What: astrophysics seminar/lecture

When: May 23th, 2025, 15:00-16:30 CET

Where: Building C - Room 131  (ground floor)

Speaker: Dr. Germano Sacco - INAF Osservatorio astronomico di Arcetri

Title: Studiare la formazione e l'evoluzione dei sistemi stellari giovani attraverso grandi survey dalla terra e dallo spazio e l'intelligenza artificiale

Abstract: Le stelle si formano in gruppi composti da un numero di oggetti che varia da poche decine a decine di migliaia, in seguito al collasso e alla frammentazione di nubi molecolari turbolente e magnetizzate. I sistemi stellari giovani che si formano durante questo processo nella maggior parte dei casi si disperdono nel campo galattico entro 10 Milioni di anni oppure formano ammassi aperti che sopravvivono per tempi più lunghi. Studiare le proprietà dei sistemi stellari giovani, capire i processi fisici che determinano la loro formazione e dissoluzione è importante per rispondere alle domande aperte riguardanti sia la formazione del Sistema Solare che l'evoluzione della Via Lattea. In questo seminario, dopo aver descritto le principali teorie e le domande aperte in questo ambito, illustrerò le principali scoperte degli ultimi anni che sono state ottenute, principalmente, grazie alla missione spaziale Gaia e a grandi campagne osservative realizzate con telescopi a terra. Infine, discuterò alcuni progetti per il prossimo futuro, sottolineando anche quale possa essere il ruolo dell'Intelligenza Artificiale. principalmente, grazie alla missione spaziale Gaia e a grandi campagne osservative realizzate con telescopi a terra. Infine, discuterò alcuni progetti per il prossimo futuro,sottolineando anche quale possa essere il ruolo dell'Intelligenza Artificiale.

Notes:  seminario a carattere introduttivo (di circa 75 minuti), rivolto principalmente a studenti o non esperti del settore.

What: astrophysics seminar

When: May 22nd, 2025, 11:30-12:30 CET

Where: Building C - Room 241  (first floor)

Speaker: Dr. Laura Sommovigo - CCA, Flatiron Institute

Title: Dust in the Reionization Era

Abstract: JWST, in combination with ALMA and NOEMA, is opening an unprecedented window into early galaxy formation—providing access to both continuum and line emission from the rest-frame ultraviolet (UV) to the far-infrared (FIR) out to redshift z ≈ 10, and spatially resolved information up to z ≈ 7. These data are beginning to constrain, albeit with large uncertainties, the star formation histories, metallicities, and interstellar medium (ISM) conditions of galaxies within the first billion years of cosmic time. In this talk, I focus on the role of dust, from its attenuation and scattering in the rest-frame UV–optical to its re-emission in the FIR. Often treated as a nuisance and modeled with fixed templates, dust is in fact central to interpreting galaxy observables across cosmic time. I present a framework for self-consistent dust modeling across wavelengths, combining analytic prescriptions with insights from hydrodynamical and radiative transfer simulations—including cosmological (TNG), zoom-in (SERRA), and isolated setups. I compare this in-progress model to recent JWST and ALMA/NOEMA observations from large programs such as REBELS and CRISTAL-ALPINE, highlighting key challenges in reproducing the observed properties of early galaxies. I conclude by outlining future steps toward refining dust models and integrating them into next-generation multi-wavelength analyses of the high-redshift Universe.

What: phenomgrav astrophysics seminar 

When: May 15th, 2025, 16:30-17:30 CET 

Where: Building C - Room 131  (ground floor) 

Speaker: Dr. Riccardo Buscicchio -  Università degli Studi di Milano-Bicocca 

Title: Emergence of Milky Way structure in the first year of LISA data 

Abstract: Tens of thousands of gravitational-wave (GW) sources are expected to be detected by the Laser Interferometer Space Antenna (LISA) during its mission. The largest majority of such sources will be persistent signals from the Milky Way (MW). While individual resolvability will improve over the mission timescale, the whole population will persistently contribute to the LISA data stream from day one, piling up in a confusion noise. In this talk, I will overview current prospects for MW spatial distribution reconstruction, discuss the implications on the confusion noise time variation. Doing so, I will present a fast and accurate inference taking into account both. Employing a realistic data segmentation, I will present a Hamiltonian-Montecarlo scheme capable to (i) infer on the Galactic shape and (ii) accomodate for the presence of gaps. Our approach opens the door to quantify the evidence for Milky Way structure while performing a Global fit.

What: astrophysics seminar

When: March 19th, 2025, 11:00-12:00 CET

Where: Building C - Room 250  (first floor)

Speaker: Lapo Querci - Università degli Studi di Firenze

Title: The formation of stellar halos in ultra-faint dwarf galaxies through mergers

Abstract: Ultra-faint dwarfs (UFDs) are believed to be relics of the Universe's earliest galaxies, and recent observations of extended stellar halos around them can give precious insights into their evolution. These halos may form through tidal interactions, early supernova feedback, or mergers. In this talk, I will present our investigation of how merger properties influence the formation of stellar halos, focusing on Tucana II, the most promising UFD assembled through mergers. Using N-body simulations, we systematically explored different trajectories, merger mass ratios, dark-to-stellar mass ratios, and stellar size of the progenitors, and trained a neural network emulator to efficiently explore the parameter space. Our findings show that the merger mass ratio is the prime driver of the stellar halo formation, and applying these results to Tucana II, we find that its observed stellar halo properties are consistent with “intermediate” mergers. Our work highlights the potential of stellar halos as tracers of the smaller progenitor galaxies. Ongoing and planned spectroscopic surveys will greatly increase the statistics of observed stars in UFDs, and thus of their associated stellar halos. Interpreting such observations with our simulations will provide new insights into the assembly history of UFDs, and hence the early galaxy formation process.

What: astrophysics seminar

When: March 18th, 2025, 16:30-18:00 CET

Where: Building C - Room 248  (first floor)

Speaker: Dr. Vaclav Pavlik - Astronomical Institute, Czech Academy of Sciences

Title: Black holes and where to find them

Abstract: Black holes are among the most fascinating objects in the universe. Once considered purely theoretical, now they are observed across a vast range of cosmic environments, from the remnants of massive stars to the supermassive giants in the cores of galaxies. But we are still unable to conclusively prove the existence of the intermediate-mass category. I will explore the most likely places where the intermediate-mass black holes should reside and some of our attempts to detect them.

What: phenomgrav astrophysics seminar

When: March 5th, 2025, 14:30-15:30 CET

Where: Building C - Room 250  (first floor)

Speaker: Antonio Matteri - Scuola Normale Superiore

Title: Can primordial black holes explain the overabundance of bright super-early galaxies?

Abstract: JWST is detecting an excess of high-redshift (z ≳ 10), bright galaxies challenging most theoretical predictions. Several physical phenomena have been considered as possible causes, ranging from astrophysical to cosmological reasons. In this context, we investigate the impact of Primordial Black Holes (PBHs) on the halo mass function and UV luminosity function of super-early galaxies, by exploring two key effects: (i) the enhancement of massive halos abundance due to the compact nature and spatial distribution of PBHs; (ii) the boost to galaxy luminosity due to Active Galactic Nuclei powered by matter accretion onto PBHs. Using Bayesian analysis, we find two possible scenarios to solve the tension: (a) either massive, non-emitting PBHs or (b) low-mass ones powering super-Eddington AGNs. Although the former is in tension with current limits on PBH abundance, the latter hints at a possible solution to the problem.

What: astrophysics seminar

When: March 13th, 2025, 14:30-15:30 CET

Where: Building C - Room 131 (ground floor)

Speaker: Dr. Livia Vallini - INAF Bologna

Title: The properties of the interstellar medium in galaxies during the Epoch of Reionization

Abstract: The Epoch of Reionization (EoR) represents a critical phase of the Universe during which the first galaxies started to rapidly form stars, eventually ionizing the surrounding intergalactic medium. For this reason, shedding light on how the gas is converted into stars, and how this process is influenced by the interstellar medium (ISM) properties and by the feedback from active galactic nuclei, holds the key to shedding light on the reionization process. In this talk, I will present a new physically motivated model that, taking spatially resolved line and dust continuum emission as inputs, allows us to derive the gas density, the gas-phase metallicity, and the deviation from the Kennicutt-Schmidt relation over sub-kpc scales in the ISM of EoR sources. I will discuss the perspectives for its exploitation on spatially resolved observations of sources recently discovered with the James Webb Space Telescope at z>10.

What: astrophysics outreach seminar

When: February 21st, 2025, 17:30 CET

Where: Building C - Room 131  (ground floor)

Speaker: Prof. Giovanni Covone - Università degli Studi di Napoli Federico II

Title: Altre Terre: la lunga storia (e l’avvincente futuro) della ricerca dei pianeti extrasolari

Abstract: Alla fine del XX secolo, gli astronomi sono riusciti finalmente a verificare le previsione filosofiche di Epicuro e Giordano Bruno: il cosmo è popolato di innumerevoli altri mondi. Oggi, lo studio dei pianeti extrasolari è uno dei campi più vitali dell'astrofisica. In questo seminario, discuteremo di alcune delle tecniche di maggior successo per lo studio degli esopianeti e dei tanti successi ed insuccessi in questa lunga storia. Ma soprattutto, parleremo delle domande ancora senza risposta e delle sfide tecnologiche e scientifiche che abbiamo davanti.

Zoom link: https://infn-it.zoom.us/j/85102898000?pwd=ZbzODyYxts822aQT3UZHjyzalcD98P.1

Zoom meeting ID: 851 0289 8000
Zoom access code: 966801

Notes: il seminario è in italiano e rivolto principalmente a studenti e colleghi non esperti nel settore.