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Small-scale cosmology with dwarf galaxies

Oliver Müller

Dwarf galaxies are tracers of the fine-structure of the large-scale structure of the universe, but their predicted distribution from simulations is in serious conflict with observations in the Local Group, the best studied group of galaxies today. Recently, two planes of satellites were discovered around Cen A, providing a unique opportunity to test cosmological predictions beyond the Local Group. We surveyed the complete Centaurus Group with the Dark Energy Camera, doubling the census of dwarf galaxies in the group. We found evidence that these satellite planes are corotating, posing a major challenge to Lambda+CDM. Comparison to high-resolution dark matter simulations show that this finding is highly significant. Another part of the talk will be dedicated to the newly established and unexpected relation between the number of dwarf galaxies and the size of the bulge of the host galaxy, where I test this relation with of our ongoing survey.