In our modern understanding of the Universe, dark matter (DM) constitutes ~85% of the total mass and forms gravitationally bound halos which are the sites for galaxy formation. Galaxies contain information of their host halos, and halos react to the baryonic processes of the inhabitant galaxies — their connections are essential for understanding galaxy formation, and enable us to derive fundamental properties in the dark sector by examining the visible material. Halos and galaxies are full of substructures as a result of hierarchical merging — these “subhalos” or satellite galaxies contain valuable information of the host’s formation history as well as fundamental parameters of the Universe at large. In this talk, I will present my studies on the interplay between halos and inhabitant galaxies using cosmological simulations, focusing on the relation between galaxy morphology and host-halo structure. This includes a theoretical picture of the formation of ultra-diffuse galaxies, involving supernovae-driven outflows, ram-pressure stripping, and tidal interactions. I will also present a series of works using satellite galaxies and dwarf galaxies as testbeds of cosmology and baryonic feedback, and showcase the advantage of a combined effort using both simulations and semi-analytical models.
