The Threshold of Galaxy Formation: A Tinsley Workshop - March 8-10, 2027
Rationale & Scientific Scope
What is the minimum dark matter halo mass that can support a luminous galaxy? This 3-day workshop will focus on the physical threshold at which galaxy formation succeeds or fails, bringing together theoretical expectations, current and future prospects for discovering extremely faint stellar systems, and the observational follow-up required to determine their nature.
Day 1 — Setting the Threshold: Is there a theoretical threshold for galaxy formation? What can we learn about galaxy formation at this extreme? Are there predicted observational signatures that can guide future observations? What differentiates the formation of the lowest mass galaxies from that of similarly luminous star clusters? Topics include reionization suppression, the minimum halo mass for star formation, and theoretical predictions for where galaxy formation shuts off.
Day 2 — Searching for the Threshold: What are the current and future observational prospects to find the threshold of galaxy formation? Topics include searches for ultra-faint dwarf galaxies, surface-brightness detection limits, and what current imaging surveys (DES, DELVE, UNIONS) have revealed at the detection frontier. Early results from next-generation surveys (Rubin/LSST, Euclid, Roman, DESI, Gaia DR4), reaching ever fainter luminosities, will also be discussed, together with prospects for extending these searches beyond the Milky Way.
Day 3 — Characterizing the Threshold: How can we characterize and understand the threshold of galaxy formation using observations? Topics include the study of the faintest stellar systems through their dynamical masses, chemical abundances, binary fractions, density profiles, and other observable properties. A key question is whether these measurements are sufficient to establish the threshold of galaxy formation.