Cristiani, Valeria
Argentina IAETE – OAC
Properties of disks and spheroids in the Illustris-TNG and EAGLE simulations
Galaxies are complex stellar systems formed by several overlapping stellar components (bulge, disk, bar, etc.) whose formation and evolution process is inherently related to the individual processes undergone by each of them. We study the properties of discs and spheroids by applying two dynamical decomposition methods to a sample of galaxies with stellar masses > 10^10 M⊙ identified in the EAGLE and IllustrisTNG cosmological numerical simulations. In agreement with observational results, we find that the stellar mass fraction in the spheroidal component fsph increases systematically with galaxy stellar mass M∗ from fractions of 50% for galaxies of M∗ ∼ 10^10 M⊙ to 90% for M∗ ∼ 10^12 M⊙, although with a fair amount of scatter. For galaxies with stellar masses similar to that of the Milky Way (M∗ ∼ 10^10.6 M⊙) and applying isolation criteria we find fsph ∼ 0.2 at best which is only slightly higher than the lowest values estimated observationally for local galaxies fsph ∼ 0.15. This would indicate that the cosmological volume simulations are capable of reproducing a population of disk galaxies comparable to those observed. In addition, we perform the extension and analysis of the scaling relations between mass, specific angular momentum and characteristic velocity of disks and spheroids and how they compare with those of full galaxies and those obtained observationally, such as the Tully-Fisher and Faber-Jackson relations. In addition, the dimensionless spin parameter of the halo and the stellar components are analyzed, finding that there seems to be no correlation between them. These results show how closely the formation and evolution history of the galaxy is linked to that of each of its components.