Studying gas circulation in star-forming galaxies in simulations with explicit ISM and feedback models

This Thesis presents a comprehensive study of the baryon cycle in star-forming galaxies, with a particular focus on gas circulation between the galactic disc and the circumgalactic medium (CGM) and its role in sustaining star formation. To explore the complex interactions between these galactic components, I use cutting-edge hydrodynamical N-body simulations of Milky Way-like galaxies, incorporating a CGM around the disc. These simulations are performed with the moving-mesh code Arepo coupled with the SMUGGLE model, which includes essential stellar feedback processes, enabling the realistic simulation of the interstellar medium and the generation of multiphase outflows. In the first part of this Thesis, I analyze the role of the CGM as a reservoir for star formation, finding that stellar feedback effectively acts as a positive feedback mechanism, generating galactic fountains that recycles gas between the disc and the corona. This circulation enhances gas cooling and accretion from the CGM, fueling the star formation in the disc. In the second part, I go through the vertical and radial gas flows that transport CGM gas to the galactic disc and from the outer disc to the central regions, respectively. These processes support continuous star formation, with coronal gas preferentially accreting at larger radii before being funneled inward. Finally, using hybrid-cosmological simulations, I examine galactic outflows as a multiphase phenomenon, revealing distinct cold, warm, and hot gas phases, each with unique roles in mass and energy transport. The cold phase primarily transports mass, while the hot phase dominates in energy and momentum, reaching greater distances from the disc. This Thesis will provide deeper insights into the evolution of star-forming galaxies, contributing to a more comprehensive understanding of galaxy formation and evolution.