Introducing the Rhea simulations of Milky Way-like galaxies I. Effect of gravitational potential on morphology and star formation

The Milky Way is a complex ecosystem. We can obtain detailed observations of it by probing the physical mechanisms that determine its interstellar medium. For a detailed comparison with observations and to provide theories for missing observables, the Milky Way must be modelled as accurately as possible. However, details of the Galactic structure are not fully defined by observations, which raises the need for more generalised models. With the Rhea simulations, we present a set of Milky Way-like simulations containing detailed physics of the interstellar medium as well as star formation and stellar feedback. We conducted two simulations that differ in the gravitational potential: one fitted to several structural details derived from observations and another that only reproduces the most basic quantities. We find little difference in the overall morphology except for the bar region, which funnels gas towards the Galactic inner region and therefore prevents quenching in the centre. Despite differences with galacto-centric radius, the global star formation rate is almost identical in both setups. A spiral arm potential does not influence properties of groups of formed stars. A bar potential, however, reduces the size and formation time of those associations. We conclude that a spiral arm potential has little influence on star formation in the Galaxy, except for producing long-lived spiral structures instead of transient ones, and that a galactic bar potential has a noticeable influence on star formation, mainly within the innermost 2.5 kpc.