First Observations from the PFS Galactic Archaeology Survey

The Subaru Prime Focus Spectrograph is a new wide-field, massively multiplexed spectrograph at the prime focus of the Subaru 8 m telescope.  In March 2025, it began a 360-night survey spread over six years.  About one third of the survey is dedicated to Galactic Archaeology: (1) dark matter and chemical abundances of seven nearby dwarf galaxies, (2) the assembly history of M31 as seen through alpha element abundances, and (3) the history of minor mergers in the Milky Way as seen through the chemistry and dynamics of the most fragile parts of the Galaxy: the halo and outer disk.

The first targets for the survey were the Milky Way satellite galaxies Draco and Ursa Minor.  I will present preliminary measurements of chemical abundance distributions of these two dwarf spheroidal galaxies.  I will discuss the performance of the instrument and its software pipelines.  I will also preview the next five years of the PFS Galactic Archaeology survey.

Biography: Professor Evan Kirby specializes in using stellar spectroscopy to measure the content of stars in the nearby universe. His research concerns where and how the elements of the periodic table are created, as well as how they are dispersed into the universe. One highlight of his research is the quantification of the relationship between the stellar masses and metallicities of local galaxies. He also discovered that Type Ia supernovae in dwarf galaxies are the explosions of predominantly low-mass (sub-Chandrasekhar) white dwarfs.

Professor Kirby's primary source of data is the Keck telescopes in Hawaii. He has served on the Keck Observatory Science Steering Committee, and he is the principal investigator to upgrade the Keck/DEIMOS spectrograph. He is the co-chair of the Galactic Archaeology Working Group for the Subaru Prime Focus Spectrograph, a massively multiplexed spectrograph that will begin operation in 2025. Professor Kirby is also on the Board of Directors for the Large Binocular Telescope. (Credit: https://physics.nd.edu/people/evan-kirby/)