Joint Astrophysical Colloquium
Discovering stellar streams of globular clusters with LSST and Roman
Oleg Gnedin (U. Michigan)
Thursday 05/02/2026 @ 11:30, Sala Antonio Sollima (IV piano Battiferro)
The Legacy Survey of Space and Time (LSST) and the Roman Space Telescope will bring an explosion in the amount and quality of data on stellar streams in the Galactic halo. These streams are created by gradual unbinding of stars from globular clusters and dwarf galaxies. Their morphology and kinematics preserve rich information about the current and past tidal interactions with the Galactic environment, including the dark matter halo, stellar bar and disk, and encounters with subhalos. Over the past decade our group has developed a model for the formation and tidal disruption of star clusters throughout cosmic time. This model accurately reproduces the observed mass and metallicity distributions of the surviving globular cluster systems in nearby galaxies, and predicts the properties of stellar streams from the disrupted clusters. Mock catalogs of Galactic globular clusters and streams are publicly available. We have now developed an efficient algorithm for detecting stellar streams in photometric and kinematic surveys and already found tens of previously undiscovered streams in the Gaia data. I will present forecasts for the number and distribution of streams that LSST and Roman will discover over the next 3 years, and discuss what we can learn from them about our Galaxy.