Galaxies are intimately connected to the environments they live in. The haloes around them contain the gas reservoir from which the galaxies grow, while galactic outflows heat and enrich this ‘circumgalactic medium’ (CGM). Using ‘zoom-in’ cosmological, magnetohydrodynamical simulations, I will discuss the physical and observable properties of the gas around galaxies, focusing on Milky Way-like systems. The simulations use a new refinement technique to reach orders of magnitude higher resolution in the CGM than the current state-of-the-art. These spatially refined simulations show that the CGM has more ‘cool’ gas than previously thought, which strongly affects predicted observables in the CGM: The neutral hydrogen column densities are greatly enhanced, more in line with observations. Furthermore, I will show how the presence of magnetic fields alters the gas flows into and out of galaxies, which results in less (metal) mixing and higher gas fractions inside the halo and changes the properties of the CGM. I will also briefly discuss the effects of the enhanced resolution and presence of magnetic fields on the galaxies themselves.

Archived Recording: