Physical constraints on the central mass and baryon content of satellite galaxies

Understand

Recent analysis of the Milky Way's satellite galaxies reveals that these objects share a common central mass density, even though their luminosities range over five orders of magnitude.

• This observation can be understood in the context of galaxy formation theory by quantifying the factors which restrict the central mass density to a small range.
• One limit is set by the maximum mass that can collapse into a given region by the hierarchical growth of structure in the standard cold dark matter cosmology.
• Another limit comes from the natural thresholds which exist for gas to be able to cool and form a galaxy.