Auriga Superstars: Quantifying and improving the fidelity of stellar dynamics in cosmological galaxy simulations

Cosmological simulations of galaxies have massively improved in last decade and are now able to reproduce many properties of observed galaxy populations for a large range of masses and redshifts. At the same time, the quantity and quality of observational data has massively increased as well. For the Milky Way, in particular GAIA and various spectroscopic surveys have and continue to reveal its complex dynamical structure, including its bar, spiral arms, moving groups, streams, and satellites.

However, to interpret all the complex data we need accurate models. Stellar dynamics has mostly been modelled in idealised simulations of isolated galaxies, owing to computational and model limitations. Here I introduce a new set of high resolution cosmological zoom simulations of Milky Way-like galaxies, Auriga Superstars, that resolve their stellar disks with more than 100 million star particles at z=0.

I will first summarise the problems going to higher resolution with the Auriga (or TNG) model and quantify robustness of the Auriga model at fixed resolution, comparing different realisations of the same galaxy simulation. I will then introduce superstars method that allows us to significantly improve the mass resolution of the stellar component without changing global properties of galaxies. Finally, I will show first results of the Auriga Superstars project.