On the common mass scale of the Milky Way satellites

Understand

We use a hybrid approach that combines high-resolution simulations of the formation of a Milky Way-like halo with a semi-analytic model of galaxy formation to study the mass content of dwarf galaxies in the concordance $\Lambda$CDM cosmology.

• We find that the mass within 600 pc of dark matter haloes hosting luminous satellites has a median value of $\sim 3.2\times 10^7$ Msun with very little object-to-object scatter.
• In contrast, the present day total luminosities of the model satellites span nearly five orders of magnitude.
• These findings are in very good agreement with the results recently reported in the literature for the dwarf spheroidal galaxies of the Milky Way.