On the common mass scale of the Milky Way satellites

Abstract

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. In our model, dwarf irregular galaxies like the Small Magellanic Cloud, are predicted to have similar or slightly larger dark matter mass within 600 pc.

5 pages, 3 figures, to match the version accepted in MNRAS Letters. One paragraph added to explain the spread in luminosities more explicitly. References updated and Conclusions remain unchanged

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• Nonlinear evolution of dark matter subhalos and applications to warm dark matter
• Simulations of the accreted stellar halos of low-mass field galaxies