Something green beneath the surface: The dynamical nature of Fossil Structures in IllustrisTNG-100
The study investigated whether fossil structures (FS) are dynamically relaxed by comparing their properties to non-fossil systems (non-FS). Using simulations, researchers found that the magnitude gap in FS is driven by a lack of recent massive accretion events over the last 6 Gyr. While FS show lower satellite mass ratios, both populations remain moderately perturbed systems rather than fully relaxed ones.