Surface density profile and AVR for Milky Way-like galaxies in TNG50

Abstract

We have studied the surface density profile, ΣR, and the AVR, σvz , of stars for 25 MW-like galaxies in the TNG50 simulation and compared the results with the Kordopatis et al. and Sanders et al. catalogues of Milky Way stars. ΣR of stellar disks on spiral galaxies obeys an exponential profile where younger stars are more abundant than older stars, specially so towards the end of the disk. We argue it’s because older stars were born towards the center during the formation of the galaxy and more, younger stars were born at the newly formed disk and outer regions as they were getting hotter and denser. σvz shows a decreasing trend with galactocentric radius, though for both catalogues a plateau can be seen for R >∼ 8 kpc, attributed to a more scattered sample of stars near the edge of the stellar disk. Older stars tend to show higher velocity dispersion than younger stars due to the conditions, such as gas turbulence, of when they were formed.