Simulations of magnetized multiphase galactic disc regulated by supernovae explosions

Abstract

Context. What exactly controls star formation in the Galaxy remains controversial. In particular, the role of feedback and magnetic field are still partially understood. Aims. We investigate the role played by supernovae feedback and magnetic field on the star formation and the structure of the Galactic disc. Methods. We perform numerical simulations of the turbulent, magnetized, self-gravitating, multi-phase, supernovae regulated ISM within a 1 kpc stratified box. We implemented various schemes for the supernovae. This goes from a random distribution at a fixed rate to distributions for which the supernovae are spatially and temporally correlated to the formation of stars. To study the influence of magnetic field on star formation, we perform both hydrodynamical and magneto-hydrodynamical simulations. Results. We find that supernovae feedback has a drastic influence on the galactic evolution. The supernovae distribution plays a very significant role. When the supernovae are not correlated with star formation events, they do not significantly modify the very high star formation rate obtained without feedback. When the supernovae follow the accretion, the star formation rate can be reduced by a factor up to 30. The magnetic field is also playing a significant role. It reduces the star formation rate by a factor up to 2-3 and reduces the number of collapse sites by a factor of about 2. Conclusions. The exact correlation between the supernovae and the dense gas appears to have significant consequences on the galactic disc evolution and the star formation. This implies that small scale studies are necessary to understand and quantify the feedback efficiency. The magnetic field does influence the star formation at galactic scales by reducing the star formation rate and the number of star formation sites.