The TNG50 view of type III breaks in disc galaxies

Abstract

The outskirts of disc galaxies are known to contain vital information about the formation and evolution of such galaxies. In this dissertation, we use the TNG50 magnetohydrodynamical (MHD) simulation to study the radial density profiles of disc galaxies. We find that at z = 0, most of the galaxies (∼ 40%) are found to have Type III (up-bending) density profiles, whilst only a small fraction of disc galaxies (∼ 10%) were found to have Type II (down-bending) density profiles. This continues to show how Type II profiles tend to disappear in the mass density profile. Moreover, we find that although bars do not seem to influence the type of break, they do influence the location of the break radius, with barred galaxies having a larger Rbreak/Reff than unbarred galaxies. We also find that ∼ 30% of Type III breaks are associated with the nearly spherical stellar halo. We attribute mergers as being the formation mechanisms for the intrinsic Type III breaks.