The masses of Local Group dwarf spheroidal galaxies: The death of the universal mass profile

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We investigate the claim that all dwarf spheroidal galaxies (dSphs) reside within halos that share a common, universal mass profile as has been derived for dSphs of the Galaxy.

• By folding in kinematic information for 25 Andromeda dSphs, more than doubling the previous sample size, we find that a singular mass profile can not be found to fit all the observations well.
• Further, the best-fit dark matter density profile measured for solely the Milky Way dSphs is marginally discrepant (at just beyond the 1 sigma level) with that of the Andromeda dSphs, where a profile with lower maximum circular velocity, and hence mass, is preferred.
• The agreement is significantly better when three extreme Andromeda outliers, And XIX, XXI and XXV, all of which have large half-light radii (>600pc) and low velocity dispersions (sigma_v < 5km/s) are omitted from the sample.