談話会
Colloquium

Salvatore Taibi（EPFL）
The dwarf galaxy tale: from the Large Magellanic Cloud to the ultra-faint systems
Dwarf galaxies are the smallest galactic systems, yet they are key probes of how galaxies form and evolve. Abundant throughout the Universe, they are often found as satellites of larger galaxies such as the Milky Way. Our galactic neighbourhood offers a unique laboratory: nearby dwarf galaxies can be resolved into individual stars and studied in exquisite detail through spectroscopic and photometric observations. From their dynamical and chemical properties, we can reconstruct not only their internal evolution, but also how they have contributed to the hierarchical growth of our Galaxy. In this talk, I will provide an overview of the Milky Way satellite system and its orbital properties, using the Magellanic Clouds as an example of ongoing hierarchical accretion. I will then turn to the internal properties of dwarf galaxies, showing how the comparison between satellites and isolated systems allows us to disentangle the effects of environment (including tidal interactions and ram pressure stripping) from intrinsic evolutionary processes. Finally, I will focus on the most dark-matter dominated and chemically pristine systems known, the ultra-faint dwarf galaxies. Their star formation having been halted by reionization, they provide a valuable insight into galaxy formation in the early Universe. Moreover, their very existence allows us to test predictions of the ΛCDM model and its small-scale tensions. I will discuss the observational challenges they present, how we can overcome them, and the open questions that future facilities will be able to answer.