2013MNRAS.433.3539G

The observed central densities of Milky Way dwarf spheroidal galaxies (dSphs) are significantly lower than the densities of the largest (Vmax ∼ 35kms-1) subhaloes found in dissipationless simulations of Galaxy-size dark matter hosts. One possible explanation is that gas removal from feedback can lower core densities enough to match observations. We model the dynamical effects of supernova feedback through the use of a time-varying central potential in high-resolution, idealized numerical simulations and explore the resulting impact on the mass distributions of dwarf dark matter haloes. We find that in order to match the observed central masses of M{sstarf} ∼ 106M☉ dSphs, the energy equivalent of more than 40000 supernovae must be delivered with 100percent efficiency directly to the dark matter. This energy requirement exceeds the number of supernovae that have ever exploded in most dSphs for typical initial mass functions. We also find that, per unit energy delivered and per cumulative mass removed from the galaxy, single blowout events are more effective than repeated small bursts in reducing central dark matter densities. We conclude that it is unlikely that supernova feedback alone can solve the `too-big-to-fail' problem for Milky Way subhaloes.