The gentle gas circulation of present-day star forming galaxies

Stellar feedback-driven outflows and extragalactic gas accretion are expected to affect significantly the distribution and kinematics of the neutral and ionised gas in and around galaxy discs. In this first part of my talk I will present the ionised gas properties in a sample of 19 nearby starburst dwarf galaxies studied with MUSE@VLT. I show that these systems exhibit mass loading factors of a few per cent, which are at least two orders of magnitude lower than expectations from theoretical models of galaxy evolution. In the second part, I will compare the HI properties of 25 simulated Milky Way-like galaxies from the TNG50 and FIRE-2 cosmological simulation suites with ultra-deep HI observations of five nearby galaxies from the MHONGOOSE survey. I show that, compared to the observations, the simulated systems feature a) a much larger fraction of low column density HI up to ~ 100 kpc from their disc; b) more complex and broader HI line profiles. We interpret these discrepancies as being the result of a more complex gas circulation due to the combined effect of stellar feedback and gas accretion. These results paint a scenario where gaseous inflows and outflows in the observed nearby Universe are much gentler than those predicted by evolutionary models in the LCDM framework.