Assembling the Milky Way Disk

Harshil Kamdar (Harvard)
Friday, December 11, 2020 - 2:00pm to 3:00pm

Combined with ground-based spectroscopic surveys, Gaia DR2 presents an opportunity to study the chemodynamical evolution of the Milky Way (MW) in unprecedented detail. The clustered nature of star formation and the presence of spiral arms in our Galaxy should produce a high degree of structure in both the kinematics and the chemical make-up of stars. In this talk, I will present a new dynamical model of the Galactic disk that takes into account the clustered nature of star formation. This model predicts that the combined phase and chemical space is rich in substructure, and that this structure is sensitive both to the precise nature of clustered star formation and the large-scale properties of the Galaxy. The model self-consistently evolves 4 billion stars over the last 5 Gyr in a realistic potential that includes an axisymmetric component, a bar, spiral arms, and giant molecular clouds (GMCs). We demonstrate that the combination of chemical and phase space information is much more effective at identifying truly co-natal populations than either chemical or phase space alone. We also present a more holistic view of the Galactic disk by characterizing the spatial and kinematic two-point correlation function in data, our simulations, and cosmological zoom-in simulations. We find evidence for clustering due to hierarchical star formation, disrupting star clusters, and resonances caused by non-axisymmetries of the disk. The results presented here bode well for harnessing the synergies between Gaia and spectroscopic surveys to reveal the assembly history of the Galactic disk.

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