On the common mass scale of the Milky Way satellites

TL;DR

This study combines simulations and semi-analytic models to show that Milky Way satellite galaxies have a nearly constant dark matter mass within 600 pc, despite wide luminosity variations, aligning with observed dwarf spheroidals.

Contribution

It introduces a hybrid simulation and semi-analytic approach revealing a universal mass scale for Milky Way satellites in the $ m f extit{ ext{Lambda}}$CDM cosmology, with minimal scatter.

Findings

Median mass within 600 pc is ~3.2×10^7 Msun for luminous satellites.

Luminosities vary over five orders of magnitude.

Dwarf irregulars like the Small Magellanic Cloud have similar or larger dark matter mass within 600 pc.

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.