Effects of feedback and resolution on galaxy formation at z = 3

Sammanfattning

Astrophysicists have long studied the early Universe in an attempt to explain where galaxies, and by proxy us, come from. In this thesis, the global properties of galaxies at z = 3, where star formation plays a large part , are studied when changing the stellar feedback strength and resolution in simulations. The simulation code used is based on RAMSES, using a similar setup to VINTERGATAN. Four simulations were run: one with fiducial supernova energies, one with half the fiducial energy, one with twice the energy, and lastly a fiducial simulation with lower spatial and mass resolution. These simulations have shown that when increasing feedback, the gas outflows from galaxies increase, enriching the circumgalactic medium (CGM) with metals and higher temperatures. Furthermore, higher feedback spreads gas more evenly across the galactic disk, broadening the stellar and dark matter distribution. High-resolution simulations using this feedback model seem to overestimate the Kennicutt-Schmidt slope, while the low-resolution simulations seem to follow it precisely. This leads to the low-resolution run corresponding to doubling the feedback in high-density regions in most global properties and distributions. Lowering the resolution does, however, incorrectly overestimate the gas temperature in both the galactic disk and CGM compared to all high-resolution simulations.