IAUS379: Dynamical Masses of Local Group Galaxies

Dwarf galaxies are regarded as the oldest and most numerous galaxy type in the Universe, responsible for the formation of the higher mass galaxies we see today. While we know a lot about the properties of dwarfs in the Local Group as well as selected nearby groups and clusters, our understanding of these galaxies beyond the Local Volume is comparatively poor. The properties probed by this restricted range of locations may be statistically deviant and therefore investigating these objects in a large variety of density environments is critical towards a more complete understanding of galaxy formation and evolution. Through the study of dwarfs, a number of small-scale challenges of the $\Lambda$CDM paradigm have emerged over the years. While issues such as the missing satellite, the "Too-Big-to-Fail", and the cusp-core problem can increasingly be resolved by including baryonic physics and by altering the properties of dark matter, the so-called planes-of-satellites problem remains unsolved. Dwarf satellite galaxies in our Milky Way and different galaxy systems in the Local Volume appear to be arranged in thin, vast planes. It has been argued that these phase-space correlations can not be explained to a satisfactory degree by the standard model of cosmology but it is unclear whether these planes in our neighborhood are statistical outliers, or if they are perhaps a common phenomenon in the Universe. Recent deep imaging surveys have significantly increased the number of known dwarf galaxies and allow us to advance these tensions beyond the Local Volume. I will present our study analyzing the spatial distribution of 2210 dwarf galaxies identified in the MATLAS survey as well as results from follow-up observations with the MUSE instrument on the VLT. Spectral information for 56 of these dwarf galaxies, situated in low-to-medium density environments, allow for a deeper dive into their properties and for a comparison to the Local Volume dwarfs.