Modeling the Chemical Evolution of the Milky Way with Radial Migration

We model the chemical evolution of the Milky Way disk with a hybrid method that combines conventional one-zone models in a series of radial annuli with radial migration of stars as predicted by a cosmological hydrodynamic simulation. We use the Versatile Integrator for Chemical Evolution (VICE; Johnson & Weinberg 2019; arxiv:1909.02598) for each radial zone, accounting for chemical enrichment by stars that enter or leave the zone over the course of the simulation. In doing so, we find that recently observed anomalies in age-abundance relations observed by APOGEE, such as an old metal-rich population (e.g. Feuillet et al. 2018, MNRAS, 477, 2326) and a young alpha-rich population (e.g. Martig et al. 2016, MNRAS, 456, 3655; Feuillet et al. 2019, MNRAS, 489, 1724), occur naturally due to radial migration within the disk, which has an impact on the SN Ia rate at fixed radius. We are exploring these models further to also quantify their impact on the bimodality of stars in the [α/Fe]-[Fe/H] plane, and how these results are impacted by spatial and temporal variations in the star formation history of the simulated galaxy. These findings suggest that the positions of stars at intermediate times while migrating from birth to final orbital positions are necessary to accurately understand disk galaxy chemical evolution.