Recent years have seen major advances in both observations and simulations of the Milky Way. The combination of Gaia with large stellar spectroscopic and asteroseismic surveys, together with increasingly realistic galaxy simulations, has transformed our understanding of how the Galaxy formed and evolved. While a broad framework is now in place, key uncertainties remain, preventing a robust and widely accepted timeline of the Milky Way's assembly.

This workshop aims to bring together researchers working across observations, theory, and simulations to address three central areas of Galactic archaeology, with particular relevance to surveys and facilities with strong European involvement:

1) The Milky Way's building blocks and merger timeline

What were the properties of the systems that built up the Milky Way? How did mergers affect star formation, Galactic structure (e.g. disc formation and heating, bar formation) and chemodynamic evolution? When did mergers occur and how major or minor were they? Where does their accreted debris reside today, and to what extent do these signatures persist over time?

2) The proto-Milky Way and high-redshift galaxy formation

How did the Milky Way assemble in the first few billion years? How should in situ and accreted populations be defined prior to disc formation? What role did star clusters play at the earliest epochs? Is there evidence for an ancient in situ stellar halo, and how does this relate to extremely metal-poor disc stars?

3) The typicality of the Milky Way's accretion history

Is the Milky Way and its accretion history representative of galaxies of similar mass? How should Milky Way analogues be defined in observations and simulations? What effect does the local environment have on the assembly of the Milky Way? How can the Milky Way be connected to galaxies at cosmic noon and high redshift?

Contributions addressing these questions from observational, theoretical, simulation-based, or combined perspectives are encouraged.

Programme

The workshop will be organised into three question-driven sessions, corresponding to the themes above. Each session will include invited talks and contributed talks selected from anonymised abstracts, with preference given to early-career researchers.

Speakers are strongly encouraged to elaborate on what key data, tools, or proxies (e.g. gas tracers or a specific age precision) are still missing and which efforts, such as European surveys, are underway to deliver them.

Each session will conclude with short, focused discussions on future directions, addressing how current and upcoming survey data can be most effectively coupled with simulations to answer the session's overarching questions.

Invited speakers

• To Be Announced

Scientific organisers

Co-chairs: Sven Buder (Australian National University Canberra), Emma Dodd (Durham University), Danny Horta (University of Edinburgh), Stephanie Monty (CIERA Northwestern, New Mexico State University)

Contact

sven.buder @ anu.edu.au, emma.l.dodd @ durham.ac.uk, smonty @ nmsu.edu, dhortad @ ed.ac.uk