Astronomy Colloquium: Elena D’Onghia

Date: Wed. March 30th, 2016, 11:00 am-12:00 pm

The Structure and Dynamics of the Milky Way Stellar Disk

Elena D’Onghia (U Wisconsin)

Ongoing surveys are revolutionizing our understanding of Galaxy dynamics. At the same time, advances in computational cosmology have led to improved predictions for the properties of galaxies in the LCDM theory. This simultaneous progress has transformed the field of the dynamics of the Milky Way and its dwarf galaxies into a powerful testing ground for both cosmological and galaxy formation theories.  One important result of the last decades is that cosmological simulations of the Milky Way overpredict by a large factor the number of dwarf satellite galaxies orbiting our Galaxy. I will present numerical experiments illustrating how this population of dark and visible satellites may affect the structure of the stellar disk. I will also discuss how a satellite as massive as the Sagittarius dwarf galaxy passing through the disk excites coupled stellar motions in the solar neighborhood, leading to coherent vertical oscillations of the disk. These findings have implications for the local disk density estimate, and the amount of dark matter at the Sun’s location. I will argue that, even in the JWST era, the study of the Milky Way may be our best probe of physical processes driving the formation and evolution of spiral galaxies.