A holistic view on (dwarf) galaxy formation

Many processes in the Universe occur on enormous scales, both spatial (millions of light- years) and temporal (billions of years). Theories related to cosmology and galaxy formation can therefore typically not be tested in laboratories and observations only show a snapshot of different stages of galaxy evolution. With the help of computer simulations these theories can be tested (for example: what exactly is the dark matter particle?) by comparing the properties of simulated galaxies to those of observed galaxies in the real Universe. The level of agreement allows conclusions on the accuracy of the tested theory. Cosmological simulations do not only model individual galaxies but a volume of the Universe that contains a full population of galaxies with thousands of galaxies. These simulations are computationally very expensive and require the computing power of modern supercomputers. In the last decades these simulations included more and more details but discrepancies remain, especially concerning the smallest galaxies: the so- called dwarf galaxies. Dwarf galaxies are particularly sensitive to the details of the implementations of processes related to the description of the interstellar medium because of their low total mass. These processes are often unresolved and rely on assumptions and simplifications. In addition, variations on the exact type of dark matter, for example: cold or warm, or self- interacting dark matter impact the properties of dwarf galaxies more than those of larger galaxies such as our Milky Way. This project analyses dwarf galaxies from multiple novel cosmological simulations of various types of dark matter for which the interstellar medium is modelled in unprecedented detail. This elaborate description allows in-depth comparisons with additional observations in many wavelength ranges which would not be possible with earlier, more simplistic models. The current discrepancies between observed and simulated dwarf galaxies are investigated from multiple angles. Was the previous method to describe the interstellar medium too simplistic and therefore inaccurate? Or do the differences indicate that we need to fundamentally reconsider the current standard model of cosmology, which assumes a form of cold" dark matter? How robust are the comparisons between the observed and the simulated galaxies?