Probabilistic model for dynamic galaxy decomposition

In the era of precision cosmology and ever-improving cosmological simulations, a better understanding different galaxy components such as bulges discs will give us new insight into galactic formation evolution. Based on fact that stellar populations constituent galaxies differ by their dynamical properties, we develop two simple models for decomposition using IllustrisTNG hydrodynamical simulation. The first model uses single parameter can distinguish 4 components: thin disc, thick counter-rotating disc bulge. second one more parameter, was defined in probabilistic manner, distinguishes bulge disc. number fraction disc-dominated at given mass obtained our agrees well with observations masses exceeding $ \log_{10}(M_*/M_\odot)=10$. S\'ersic indices half-mass radii agree those real galaxies. mode distribution is expected value $n=1$. However, are smaller than galaxies, accordance previous findings simulation produces undersized discs.