Date: Wednesday 30-Oct-2024
Time: 11:30-12:30 pm
Location: PSC 1136
Speaker: Anirudh Chiti (University of Chicago)
Title: Uncovering the ancient Milky Way with the DECam MAGIC survey
Abstract: The ancient stellar populations of the Milky Way and its surrounding dwarf galaxies are a window on the earliest stages of galaxy formation and element production. In particular, the Milky Way’s ultra-faint dwarf galaxies (UFDs) are the products of early galaxy formation on the smallest scales, and its lowest metallicity stars are plausibly directly enriched by the first stars. Recent, metallicity-sensitive imaging techniques have dramatically increased the efficiency of identifying such stars, with potential to significantly advance this field. I will present one set of results highlighting this: the detection of an extended population of low metallicity stars around several dwarf galaxies, highlighting the Tucana II UFD, indicating that several of these relic systems may host extended stellar populations. In the case of Tucana II, in which we detect stars out to ~1 kpc (~8 r_h), I will also present their detailed chemistry and interpret these signatures in the context of formation mechanisms of its outer regions. I will use these results to motivate the DECam MAGIC survey— a new survey on the Dark Energy Camera survey— that will image a quarter of the southern sky with a new metallicity-sensitive imaging filter 2-3 magnitudes fainter than similar existing photometry in the southern hemisphere. This survey will unlock new discovery space in the low metallicity, faint regime of the Milky Way across a broad region of the sky, with potential to dramatically increase the sample of low metallicity stars and provide direct insights on the products of the first stars.
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