Title: What Can We Learn from Galaxies' Stellar Halos?

Speaker: Professor Sergey Koposov （University of Edinburgh）

Time: 15:00pm, June 5, 2026

Location: 5-516, PMO Xianlin Campus

Abstract: Galactic stellar halos are thought to form primarily from accreted low-mass galaxies and globular clusters. Recent massive imaging and spectroscopic surveys have transformed our view of these structures. Distinct halo substructures—separate from intact orbiting satellites—are the debris from disrupted systems known as stellar streams. With ~100 now identified in the Milky Way and Andromeda, these streams allow us to map the local dark matter distribution and probe for starless dark matter subhalos. Beyond streams, the kinematics of the accreted halo reveal the complex history of the Milky Way’s assembly and its interaction with the Magellanic Clouds. In this talk, I will present recent results on the Milky Way and M31 stellar halos, primarily based on the S5 spectroscopic survey of stellar streams and the stellar component of the Dark Energy Spectroscopic Spectroscopic Instrument (DESI) survey.