Title: Assembly History of the Ancient Halo and Disk in the Auriga Simulation

Speaker: Dr. SungWon Kwak (AIP)

Date&Time: 2024-11-29, 11:00 AM

Location: Science Hall B102

Talk to be delivered in English
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Abstract: Galaxies consist of multiple components, such as the disk, bulge, bar, halo, and infalling satellites. By tracing the evolutionary path of each component, we aim to suggest a possible formation history for the Milky Way. Our study begins with the Milky Way’s stellar halo by comparing the spherical density distribution up to 100 kpc between the observed RR Lyrae variables (RRLs) and the old stellar halos from the Auriga simulation. This extensive set of cosmological zoom-in simulations of Milky Way-like galaxies allows us to statistically probe the 3D stellar distribution of the stellar halos and compare it with our extensive observational catalog of photometric data for 178K RRLs. We find that the Milky Way is likely to have undergone the process of ‘many minor mergers,’ unlike other galaxies with ‘a few massive progenitors’ that possess steep density profiles.

In the ancient disk component, we present around one hundred Gaia RRLs on the Toomre diagram and discuss the origin of old stars that are metal-rich and exhibit disk-like dynamics, comparing these results to the Auriga simulations. We suggest that the redistribution of the dynamics of satellite galaxies is the key parameter in explaining the origin of the rotation of the ancient disk.
In the final part of the talk, we briefly introduce ongoing projects on galactic dynamics and bar formation in isolated simulations using N-body simulations computed with our GPU code.