We are pleased to announce the Third GWCats workshop which will take place in Toulouse, France, from 23 to 25 November 2026. 

GWCats: gravitational waves science with galaxy catalogs

GWCats is a cross-disciplinary initiative which aims at gathering together members of the gravitational wave community and members of the astronomical community in order to explore and enable the science emerging from combining gravitational wave observations and electromagnetic surveys, in particular galaxy catalogues.

Goals of the workshop

This is the third workshop of the GWCats initiative, with the previous ones held in Glasgow in 2024 and in Leiden in 2025. The goals of the workshop are multiple: discuss results from ongoing collaborative projects within GWCats, promote both internal and external collaborations, explore new opportunities to expand the science of GWCats, and organise its activities.

Workshop organization

The workshop is organised over three days, with the first two fully dedicated to science and the last one dedicated to GWCats scientific and administrative organisation. All participants are encouraged to stay until lunch on the third day.

There are no registration fees, but there is a maximum number of 60 participants.

Coffee breaks and lunches will be provided to all participants.

Workshop Website

From astrophysics to high-energy physics, from information theory to quantum gravity, black holes have acquired an ever increasing role in fundamental physics, and are now part of the terminology of many important branches of observational, theoretical and mathematical physics.

The Black Holes Workshops gather researchers working on physical and mathematical problems of black holes, both in their classical and quantum aspects, as well as their connections to general relativity and gravitation, string theory, cosmology, and astrophysics, and stimulate the interaction between all these issues.

The workshop will take place at the University of Minho, in December 17 and 18, 2026. Researchers on black holes in all their aspects are invited to participate. Registration for the event will start on September 14th and end on November 30th. The deadline to submit abstracts is November 21st. A limited number of accepted contributions will be selected, taking into account their scientific merit. Submissions of abstracts after the deadline will not be allowed. Please follow the registration instructions.

In this edition there will be no registration fee for participants.

Scientific Organizing Committee

Vitor Cardoso (CENTRA/IST) João Costa (CAMGSD/ISCTE) Carlos Herdeiro (CIDMA/Aveiro University) José Sande Lemos (CENTRA/IST) Filipe Mena (CAMGSD/IST) José Natário (CAMGSD/IST)

Local Organizing Committee

António Morais (LIP-Minho/UM) Ricardo Ferreira (CF-UM) A. Onofre (CF-UM) N. Barros (LIP-Minho/UM) N. Castro (LIP-Minho/UM) H. Carvalho (LIP-Minho) M. Finetti (LIP-Minho) J. Gonçalves (LIP-Minho) V. Oliveira (LIP-Minho) I. Martins (LIP-Minho/UM) D. Araújo (LIP-Minho/UM)

Workshop Website

MAD Workshop is an excellent opportunity to connect with collegues involved in the development of advanced materials for gravitational wave detectors as well as with researchers from crystal growth community and industry who share a deep interest in the topic. Together we will discuss recent achievements and challenges in material research and outline prospects for future cooperation. We are confident that face-to-face workshops with a lot of space for personal interaction and individual meetings will contribute to achieving our common goals.

Workshop Website

The workshop will focus on compact object binaries ranging from stellar mass objects to supermassive black holes. The workshop aims to discuss our current understanding of gravitational-wave sources based on the previous gravitational-wave and electromagnetic observations and what we will be able to learn from future observations. Topics to be considered at the workshop include:

Dynamical channel of binary black hole formation
Binary stellar evolution/population
Binary black holes in AGNs
Intermediate - supermassive binary black holes
Electromagnetic signatures of compact binaries
Gravitational-wave data analysis

The workshop is hosted by the Research Center for the Early Universe at University of Tokyo.

Participation and Program

All participants are requested to register by filling out the “Registration” form via the menu on the left of this page. Participants interested in contributing with a talk must also submit an abstract by filling out the “Title of talk” and “Abstract”,  in the registration form. The workshop can accept a limited number  of participants due to the capacity of the room.  In order to receive full consideration, all information must be received by September 15th, 2026. The acceptance of the workshop will be given by September 25th, 2026. 

We plan to focus on invited and contribution talks in the first week. In the second week, we will have a  small number of  talks and  a large fraction of time will be devoted to open discussion. 

Venue

The workshop will take place at Science building No. 1 in the Hongo campus of University of Tokyo.  

Registration fee

The registration fee is 5000 JPY (~33 USD, 30 EUR).  The cost of workshop dinner is  7,000 JPY. The payment method will be annouced later to the accepted participants.

Workshop Dinners

To be determined.

Accommodation

We recommend any business hotel in the Hongo or Ueno area. For example, APA Hotel Keisei Ueno-Ekimae is a business hotel at a walkable distance from UTokyo, just across the Ueno park. Other APA hotels are also nearby (Ueno Eki Minami, Ueno Ekimae, Shin Okachimachi Ekimae). There are many other hotels in the Ueno area.

If you want to stay farther away from the university, commuting by metro is also an easy option. The Hongo campus is well connected to the Marunouchi and Oedo lines (Hongo Sanchome station), the Namboku line (Todaimae st.) and the Chiyoda line (Nezu st.).

For using local transportation, we recommend buying a rechargeable Pasmo (or Suica) card.

Invited Speakers

• Pau Amaro Seoane (Polytechnic University of Valencia)*
• Clement Bonnerot (U of Birmingham)
• Alexander Dittmann (IAS)
• Kohei Inayoshi (KIAA)
• Maximiliano Isi (Columbia)
• Dong Lai (TDLI)
• Wenbin Lu (UCB)
• Andrew MacFadyen (NYU)
• Lucio Mayer (UZH)
• Ehud Nakar (Tel Aviv)
• Smadar Naoz (UCLA)
• Matt Nicholl (Queen’s University Belfast)
• Samaya Nissanke (DESY)
• Re’em Sari (Hebrew U)
• Ataru Tanikawa (Fukui Prefectural U)
• and more (* to be confirmed)

Organizers

• Kenta Hotokezaka, University of Tokyo
• Daniel D’Orazio, Space Telescope Science Institute
• Martin Pessah, Niels Bohr Institute
• Johan Samsing, Niels Bohr Institute
• Soichiro Morisaki, University of Tokyo
• Masaki Ando, University of Tokyo
• Tomoya Kinugawa, Shinshu University

Contact

• Workshop LOC < resceu-nbia-2026-group at g.ecc.u-tokyo.ac.jp >

We gratefully acknowledge the support by the Research Center for the Early Universe at University of Tokyo, the JST FOREST Program (JPMJFR2136) and the JSPS Grant-in-Aid for Scientific Research (23H01169, 23H04900).

Workshop Website

How binary black holes and neutron stars form and merge is the central question in gravitational-wave astrophysics. A decade after the first direct detection of a binary black hole merger, it remains unclear which gravitational-wave events probe the evolution of isolated massive binary stars, the dynamics of dense environments like star clusters, and active galactic nuclei, or more exotic pathways. One of the main hurdles has been the low-number statistics that prevented statistically robust identification of sub-populations within the observed population of gravitational-waves.

With the full O4 catalogue expected by the end of 2026, the sample is set to grow to several hundred events, ushering gravitational-wave astronomy into a new era of precision population inference. For the first time, this enables robust multi-parameter analyses (masses, spins, eccentricities, and their correlations) which are crucial for breaking the degeneracies that currently prevent us from deciphering the astrophysical origin of compact-object mergers.

The recent O4a and O4b releases have already prompted several interesting (and sometimes competing) claims about the origins of binary black hole subpopulations, including evidence for hierarchical mergers, features associated with the supernova-remnant mass function, and imprints of isolated binary and triple-star evolution. Many of these results remain only partially supported. In parallel, EM observations from (like the Gaia DR4 release) are substantially expanding the sample of dormant compact objects in binaries with luminous companions, providing essential context for interpreting gravitational-wave events.

Taking place just a few weeks after the planned full O4 data release, the workshop will be a timely opportunity to discuss the wealth of new results from the enlarged gravitational-wave catalogue. It will bring together researchers working on astrophysical theory and modelling, numerical relativity, and gravitational-wave data analysis to explore what are the astrophysical lessons that can be robustly drawn from O4.

The workshop will have a very heavy focus on discussions and interactions to promote problem solving structured around three themes:

• Astrophysical modelling: merger signatures expected from different formation channels
• Data analysis: which features in the data are robust
• Falsification: how the new data constrain and refine astrophysical models

Registration deadline: 8 November 2026

The number of participants is limited. We will confirm participation shortly after registration closes.

Organizers

Jakob Stegmann (MPA), Lieke van Son (Radboud University), Davide Gerosa (Milano-Bicocca), Samaya Nissanke (DESY/DZA), and Salvatore Vitale (MIT).

Workshop Website

The ACME workshop, The Transient Universe in the Rubin Era, which will take place 2–6 November 2026 at Institut Pascal, Paris-Saclay University, Orsay, France.

Please note that the abstract submission deadline is 31 July 2026.

The workshop will focus on upcoming observations by the Rubin Observatory and their connection to the multi-wavelength and multi-messenger Universe. In this context, several observatories will be presented, and both current results and future prospects for observing a wide variety of transient sources will be discussed. The workshop will also feature presentations on tools and infrastructure that facilitate coordinated observations of the transient sky.

Important dates

• Abstract submission deadline: 31 July 2026
• Registration deadline: 1 October 2026
• Workshop dates: 2–6 November 2026

There is no registration fee.

For additional information, the scientific program, and registration, please visit the workshop website.

Sixth edition of the Gravi-Gamma-Nu workshop, scheduled for September 30 to October 2, 2026, at Milano Bicocca University in the Lombardy region of Italy.

This year’s workshop will be dedicated to covering the latest observational results from the new all sky surveys in the multimessenger context. The format of the workshop consists of invited and contributed talks.

Please note that registration is now open and will remain available until September 15, 2026: https://agenda.infn.it/event/50733/registrations/5769/

The workshop is limited to 100 participants, and there is no registration fee, so we encourage you to secure your spot as soon as possible. As in the past editions this workshop is a unique opportunity for PhD and early career researchers to connect with leading experts in the field.

For further information, including a list of confirmed invited speakers, please visit our website.

This workshop will bring together researchers in quantum gravity and cosmology to discuss major open questions at the interface between the two fields. Although the CDM model has been remarkably successful, increasingly precise cosmological observations have also brought a number of challenges and tensions into sharper focus. At the same time, substantial progress in quantum gravity, particularly in its applications to cosmology, has opened new possibilities for investigating the quantum origin of the universe and for seeking a more fundamental understanding of both the successes and the possible limitations of the standard cosmological model.

Addressing these questions requires closer interaction between communities that often work with different concepts, methods, and perspectives. The workshop will therefore bring together researchers from a broad range of approaches to quantum gravity and cosmology. To make the discussions accessible across these different backgrounds, speakers will be encouraged to begin their talks with a broad introduction before moving on to more specialized results and open problems.

The program will also leave substantial time for discussion, with the aim of encouraging active participation, the exchange of ideas, and sustained scientific interaction. More broadly, the workshop seeks to strengthen connections between the quantum gravity and cosmology communities, foster new collaborations, and contribute to a deeper understanding of the fundamental physics underlying our models of the universe.

Confirmed Invited Speakers

• Niayesh Afshordi — University of Waterloo; Perimeter Institute for Theoretical Physics
• Benjamin Bose — University of Edinburgh
• Suddhasattwa Brahma — Indian Statistical Institute, Kolkata
• Robert Brandenberger — McGill University
• Clare Burrage — University of Nottingham
• Bianca Dittrich — Perimeter Institute for Theoretical Physics
• Kristina Giesel — Friedrich-Alexander-Universität Erlangen-Nürnberg
• Lavinia Heisenberg — Heidelberg University
• Olaf Hohm — Humboldt-Universität zu Berlin
• Daniele Oriti — Universidad Complutense de Madrid
• Mairi Sakellariadou — King’s College London
• Yuko Urakawa — KEK Theory Center
• Victoria Venken — Kavli IPMU, The University of Tokyo
• Francesca Vidotto — Institute for the Structure of Matter, Spanish National Research Council (IEM-CSIC)

Participation

Both in-person and remote participation will be possible.

Registration will remain open until 7 September 2026, and existing registrations may be modified until 13 September 2026, including for the purpose of submitting or updating an abstract.

Please note that abstract submissions for contributed talks and posters are open only to participants attending the workshop in person.

Contributed talks and poster session

The scientific program will include a limited number of contributed talks, as well as a poster session. Participants submitting an abstract for an oral presentation may also choose to have it considered for a poster if it is not selected for a talk.

Abstract submissions are open only to participants attending the workshop in person and must be made through the registration form.

Organizers

Scientific Organizing Committee

• Robert Brandenberger — McGill University
• Elisa Ferreira — Kavli IPMU
• Oliver Friedrich — Ludwig-Maximillians-University Munich
• Luca Marchetti — Kavli IPMU and OIST
• Daniele Oriti — Universidad Complutense de Madrid
• Mairi Sakellariadou — King’s College London
• Thomas Thiemann — Friedrich-Alexander-Universität Erlangen-Nürnberg
• Jun’ichi Yokoyama — Kavli IPMU

Local Organizing Committee

• Luca Marchetti (chair)  — Kavli IPMU and OIST
• Elisa Ferreira — Kavli IPMU
• Jun’ichi Yokoyama — Kavli IPMU

Workshop Website

Gravitational wave astronomy is rapidly becoming a precision science.
With upcoming detectors on the ground and in space, we will be able to detect black holes at the edge of the observable universe and test general relativity in its most extreme regimes. However, as the measurements become more sensitive, so does the challenge of interpreting them. Small anomalies in the data could point to new physics—or just reflect environmental effects, modeling uncertainties, or instrumental noise. This workshop, part of the ERC synergy GWSky project, will bring together researchers working across theory, simulations, and observations to tackle this challenge, and build the tools and frameworks needed to make sense of future discoveries.
This workshop is by invitation only

Organizers

SOC
E. Barausse (SISSA, Italy); Z. Bern (UCLA, USA); A. Buonanno (AEI, Germany); M. van de Meent (NBI, Denmark)

Workshop Website