| 15/09/2025 |
David Radice |
Philipp Moesta |
Neutron Star Mergers: to Collapse or not to Collapse? |
Neutron star mergers act as Nature's ultimate supercolliders, where two massive objects—each with ~10^58 nucleons—collide at a quarter of the speed of light. The outcome of these mergers, whether a black hole is formed, and, if so, how quickly, is reflected in their gravitational waves and electromagnetic signals. I will discuss the physics involved in black hole formation and how it can be proved with observations. Finally, I will highlight the future potential of next-generation gravitational-wave experiments and the theoretical challenges that must be addressed to maximize their scientific impact.
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Department of Physics, Penn State, USA |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 14/10/2025 |
Anna Watts |
Philipp Moesta |
Mapping neutron stars – inside and out |
Neutron stars have a rich and fascinating phenomenology. Their supranuclear density cores contain matter of incredible neutron-richness, and they may harbor stable states of strange matter. They have solid crusts threaded by the strongest magnetic fields in the Universe, and oceans where runaway thermonuclear reactions can lead to powerful explosions. Using X-ray astronomy and General Relativity, we are starting to map these stars, inside and out — generating new insight into both stellar evolution and fundamental physics. |
Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 28/10/2025 |
Dominic Agius |
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What Can the Cosmological 21-cm Signal Teach Us About Dark Matter? |
The cosmological 21-cm signal is a powerful and novel probe of the thermal and ionization properties of the early Universe in a way that complements the cosmic microwave background. Upcoming experiments targeting this signal are poised to open up a window into the epoch of reionization and the cosmic dawn, providing key insights into star formation and the spectral emission of the first stars — properties that are currently uncertain.
Amidst these uncertainties, dark matter phenomenologists may ask the question: how would energy injections from dark matter affect the signal and lead to constraints? In this talk, I will critically assess this question, highlighting how astrophysical uncertainties shape dark matter constraints, focusing first on accreting primordial black holes. I will then present a novel mechanism through which dark matter can impact the 21-cm signal, where Lyman-alpha from decaying dark matter can enhance the 21-cm signal.
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IFIC, Valencia University, Spain |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 11/11/2025 |
Amina Helmi |
Youyou Li |
Dynamics and history of the Milky Way |
Our understanding of the Milky Way and its constituents is undergoing a revolutionary change driven primarily by the Gaia space mission, and which is further reinforced when combined with spectroscopic surveys from the ground. In this colloquium, I will highlight a few of the results stemming from the analysis of the truly spectacular Gaia data releases. Specifically, I will discuss what we have learned about the assembly history of the Milky Way thus far. I will also present some intriguing findings regarding its dynamics and our current efforts to place the Milky Way in a proper cosmological context. |
Kapteyn Astronomical Institute, Groningen, The Netherlands |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 25/11/2025 | | | | | | |
| 09/12/2025 |
Damiano Fiorillo |
Youyou Li |
Neutrino plasma: a new state of matter |
Core-collapse supernovae host the densest neutrino environments in the Universe. In these extreme conditions, neutrinos exchange flavor with each other more rapidly than they stream out of the star, forming a collective many-body system whose dynamics are dominated by weak interactions. In this talk, I will present a unified theoretical framework showing that this system behaves as a neutrino plasma, supporting collective flavor-wave excitations—flavomons—that are the exact analogs of collective electromagnetic fields in ordinary plasmas.
The stimulated emission of flavomons produces an instability, with consequent restructuring of the neutrino flavor distribution which impacts the supernova explosion and multi-messenger signature. I will show that the conditions for triggering these instabilities naturally descend from detailed balance of neutrino-flavomon interactions. By this approach, I will show that the accretion-powered neutrino outflow of supernovae generically develops neutrino-mass-induced instabilities immediately after the neutronization burst. |
Astroparticle Theory, DESY, Germany |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 13/01/2026 | | | | | | |
| 27/01/2026 |
Béatrice Bonga |
Rodrigo Vicente |
Beyond the Basics: Nonlinearities and the Messy Reality of Gravitational Wave Ringdowns |
The past decade has completely transformed our understanding of what happens after black holes collide. What we once thought could be well-described by simple ringdowns—neat linear combinations of quasinormal modes—have turned out to be far richer and messier. Today we recognize ringdowns as an intricate tapestry woven from quasinormal modes, nonlinear effects, tails, and secular phenomena like gravitational memory. In this talk, I'll dive into the nonlinear aspects: where the theory stands today and some exciting recent observational claims that we might already be seeing these effects in GW250114. In the second half, I'll switch gears to the early inspiral phase and tackle a practical question. Post-Newtonian theory is an asymptotic series, so at some point adding higher orders will yield less accurate results. Have we already reached this? By comparing PN to NR, we argue that we can still gain significant improvements by going to higher PN order, but that soon NR and PN will be equally accurate in the early inspiral. |
Radboud University, The Netherlands |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 10/02/2026 |
Luca Broggi |
Rodrigo Vicente |
The astrophysics of extreme-mass-ratio inspirals |
TBA |
Milano-Bicocca University |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 24/02/2026 |
Hyungjin Kim |
Rodrigo Vicente |
TBA |
TBA |
IPhT Saclay |
C4.174, GRAPPA, Science Park 904, Amsterdam |
| 17/03/2026 |
Elisa Resconi |
Gianfranco Bertone |
TBA |
TBA |
Technical University of Munich |
A1.16, GRAPPA, Science Park 904, Amsterdam |
| 24/03/2026 | | | | | | |
| 14/04/2026 | | | | | | |
| 28/04/2026 | | | | | | |
| 12/05/2026 | | | | | | |
| 26/05/2026 | | | | | | |
| 09/06/2026 | | | | | | |
| 23/06/2026 | | | | | | |
