The impact of massive satellite accretions on the Milky Way

DIPC Seminars

Speaker

Chervin Laporte, Kavli IPMU, Japan

When

2020/03/06
13:00

Place

Donostia International Physics Center

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In this talk, I will review recent observational and theoretical results on the Milky Way from its outermost parts in the stellar halo all the way to the solar neighbourhood. I will show that the Milky Way is far from being a quiescently evolving galaxy as often suggested and that signs of violent satellite galaxy encounters linger on, both in the stellar halo and stellar disc. In particular, I will focus on the effects of the Milky Way’s two most luminous satellites on its dynamical evolution - the Magellanic Clouds and the Sagittarius (Sgr) dwarf galaxy. I will show how the Large Magellanic Cloud is currently affecting both the kinematics of stellar halo tracers from the smooth halo to individual streams as well as that of the Galactic disc. Equally important for the Milky Way's evolution, I will discuss the origins of outer disc structures with respect to the orbital mass-loss history of Sgr, the dark matter halo wake response as well as Sgr’s tides. By presenting results from live N-body simulations of the interaction of Sgr with the milky Way, I will show that these pre-Gaia models in light of Gaia DR2 are qualitatively, and to a large degree quantitatively able to reproduce many of the recently uncovered features in the 6D Gaia samples. I will examine the origins of these various structures in the context of Sgr impact model which provides a unifying model over a decade in scale radius, with falsifiable predictions to be tested with upcoming surveys. I will argue that taking into account the presence and known effects of satellite galaxies on the Milky Way is not only important to understand the evolution of our Galaxy but also imperative to test our theories on dark matter and its clustering on small scales. Host: Raul Angulo