Scientific rationale and motivation:
Understanding galactic metal cycles requires connecting stellar physics and nucleosynthesis, gas dynamics on small and large scales, and chemical evolution - processes that operate on vastly different timescales and physical regimes. Stars produce metals with yields that depend on metallicity, evolving over millions to billions of years; those metals are transported through ISM, CGM, and IGM by processes ranging from fast supernova-driven winds to slow galactic fountain flows; this transport determines where the next generation of stars forms; and the resulting enrichment history feeds back into stellar evolution and shapes galaxy evolution across cosmic time. Yet fundamental uncertainties complicate every step: stellar nucleosynthesis predictions carry systematic uncertainties that depend on mass, metallicity, and evolutionary phase; the fraction of metals retained in galaxies versus expelled to the CGM and IGM remains poorly constrained; and mixing efficiencies within and between gas reservoirs are difficult to observe directly.
The dispersal of metals across the universe - from stellar interiors to the intergalactic medium - provides critical constraints that models must reproduce. Chemical evolution models require an accurate accounting of metal retention and loss; simulations must match observed metallicity distributions in ISM, CGM, and IGM simultaneously; both depend on understanding mixing efficiencies within and between these reservoirs. Current models make divergent predictions about metal budgets, particularly in the CGM where observations suggest substantial metal mass resides. Reconciling these predictions with observations requires understanding not just how much metal is produced, but where it ends up and on what timescales - questions that demand expertise from multiple fields.
This workshop brings together stellar astrophysicists, ISM and CGM observers, simulation and modeling experts, and chemical evolution theorists to initiate cross-field conversations that are essential but rare. Each community operates on assumptions about the others' domains: simulators adopt stellar yield tables, chemical evolution models make assumptions about outflow efficiencies, and observers interpret abundance patterns using theoretical predictions. Yet these assumptions are rarely examined collaboratively. Our goal is to assess the current state of knowledge across all components of the metal cycle and to identify where uncertainties in one domain propagate critically into others. How sensitive are metal cycle predictions to uncertainties in supernova and AGB yields? Where do simulations succeed or fail in reproducing observed metal distributions? How applicable is our understanding of metal cycles in Milky Way-mass galaxies to lower-mass dwarfs or to the early Universe?
The workshop will address these questions through five interconnected themes: metal production across diverse nucleosynthetic channels (supernovae, neutron capture processes, global yields); metal evolution in different galaxy populations (massive galaxies, dwarfs, early Universe, IGM); metal redistribution on scales from within galaxies to the IGM; metal sequestration in stars, stellar remnants, and potentially dust; and metals as tracers of the baryon cycle, galaxy assembly, and feedback processes. By examining each stage - from production to distribution to sequestration - we aim to identify where new observations, improved yield calculations, or refined simulations could most effectively close the gaps in our understanding.
Format:
To address these themes, the workshop will take place over five days (Monday evening, May 11, and Tuesday-Friday, May 12-15, 2026) at the University of Notre Dame Global Center at Kylemore Abbey in Ireland, with arrival on Monday evening and departure on Saturday morning. To facilitate genuine exchange, participation is limited to ~35 attendees, and remote participation will not be available - the collaborative nature of this meeting requires in-person engagement. The venue at Kylemore Abbey is specifically chosen for this purpose: with all participants staying, dining, and meeting in one location, spontaneous conversations and sustained collaboration become natural parts of the daily rhythm.
The meeting format balances presentation and discussion across four days. Each participant will have an opportunity to give a short talk during the first two days to establish the current state of each field. The final two days shift toward collaboration, with talks confined to morning sessions and afternoons reserved for discussions, breakout sessions, and collaborative activities. An opening reception on Monday evening will help participants from different communities connect. The goal is to foster genuine cross-disciplinary dialogue: talks should be accessible across fields, and, collectively, we aim to identify concrete areas where collaboration can advance our understanding of galactic metal cycles.
Scientific Organization Committee:
Claude-André Faucher-Giguère (Northwestern University)
Chris Howk (University of Notre Dame)
Evan Kirby (University of Notre Dame)
Nicolas Lehner (University of Notre Dame)
Freeke van de Voort (University of Cardiff)
Gail Zasowski (University of Utah)
Acknowledgement:
The workshop is organized in collaboration with Notre Dame International and hosted by the University of Notre Dame’s Kylemore Abbey Global Centre and the Department of Physics and Astronomy.
We gratefully acknowledge financial support from the College of Science, the Office of Research, and the Department of Physics and Astronomy at the University of Notre Dame.