Galactic archeology through the lens of neutron capture nucleosynthesis
The ancient stellar populations of the Milky Way dwarf spheroidal satellites provide a window into galaxy evolution and nucleosynthesis at early times. Neutron-capture abundances are of particular interest; the sites of the rapid neutron capture process (r-process) are not fully understood, and the slow neutron capture process (s-process) is uniquely useful for estimating star formation histories of dwarf galaxies. Leveraging the capabilities of medium-resolution, multi-object spectroscopy with Keck/DEIMOS, we assembled the largest homogeneous set of neutron capture element abundances in dwarf spheroidals to date. In this talk, I will compare new one-zone galactic chemical evolution models, including s-process and r-process enrichment from multiple sources, to Sr, Y, Ba, and Eu abundances in Sculptor. Having both Ba and Eu abundances in many stars in Sculptor allows us to disentangle the contributions from the s- and r-process. In addition, the Ba and Eu measurements provide constraints on the minimum delay time of neutron star mergers at early times. The neutron star merger minimum delay time changes with the inclusion of a prompt r-process source in the models, such as magneto-rotational supernovae. Including s-process Sr, Y, and Ba abundances also increases the models’ sensitivity to the ancient star formation history of Sculptor due to the precise delay time of the s-process in asymptotic giant branch stars.
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