Daniel A. D. Vaz
IA / FCUP

Abstract
Nearby, a subset of the earliest galaxies that persisted until the present day as relics of the early universe offers a unique glimpse into the past. They are known as Ultra-Faint Dwarfs (UFDs).
These UFDs are essential objects to understand as they stand among the oldest galaxies known to exist and have undergone minimal evolution since their formation. They are invaluable probes of the early universe, shedding light on the early stages of galaxy formation and evolution.
Moreover, they are excellent laboratories for studying star formation and feedback in the feeblest halos. They are ideal for placing constraints on dark matter models, given that dark accounts for up to 99% of their total mass. They represent the extreme low-mass end of galaxy assembly.
Within the cohort of UFDs, Leo T has garnered considerable attention for a compelling reason:  it is the faintest and least massive dwarf galaxy known to contain neutral gas and exhibit signs of relatively recent star formation. This sets it apart  and positions Leo T as a natural ‘Rosetta stone’ for testing galaxy formation models, which have struggled to reproduce Leo T-like galaxies until very recently.
This talk centers on a study of Leo T conducted using data from the MUSE integral field spectrograph. The high sensitivity of MUSE allowed us to obtain velocity measurements for stars as faint as magnitude ~24.
Our detailed analysis of Leo T's stellar content revealed two distinct populations of stars  characterized by contrasting ages and kinematics. The analysis also suggests that Leo T underwent minimal chemical evolution throughout its history. Notably, we have found that the kinematics of the young stellar population are consistent with those of the cold component of the neutral gas, implying a connection between recent star formation in Leo T and the cold gas component.
I will discuss these results and their implications for the origin and evolution of Leo T.

2023 October 12, 13:30

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto