Online Seminar featuring Gina Duggan: Galactic Chemical Evolution Model

Gina Duggan from Caltech gives an online seminar "Galactic Chemical Evolution Model Provides Quantitative Constraints on the r-process in Dwarf Galaxies"

Abstract: It is a challenge to distinguish which of the proposed r-process candidate sites produce the observed r-process enrichment in galaxies. We tackle this question by using a galactic chemical evolution model to match the continual build-up of r-process elements seen in our recently published catalog of dwarf galaxy abundances. The simplicity of dwarf galaxies allows a simple galactic chemical evolution model to determine the sources of r-process material. We have the largest sample of the r-process element barium (almost 250 stars) in dwarf galaxies ever assembled. Our catalog of [Fe/H], [alpha/Fe] and [Ba/Fe] for several dwarf galaxies allows us to test the possible origins of the r-process to see if the proposed amounts and timescales of these contributions can match the observations. Specifically, we test if core-collapse supernovae (CCSNe, including rare magnetorotational core-collapse supernovae) or neutron star mergers (NSMs) are the dominant source of r-process. Our method is sensitive to the clearest observational difference of CCSNe and NSMs---how quickly these events occur after the stars are created. I will discuss the details of our one-zone galactic chemical evolution model and the preliminary results that suggest a large r-process contribution from NSMs is required to produce the barium trends observed in dwarf galaxies especially at early times.