2014MNRAS.444..222G

We compare the dynamical masses of dwarf galaxies in the Local Group (LG) to those of haloes in the ELVIS (Exploring the Local Volume in Simulations) suite of Λ cold dark matter simulations. We enumerate unaccounted-for, dense haloes (Vmax ≳ 25 km/s) that became massive enough to have formed stars in the presence of an ionizing background (Vpeak > 30 km/s). Within 300kpc of the Milky Way, the number of these objects ranges from 2 to 25 over our full sample. Moreover, this `too big to fail' count grows when extended to the outer regions of the LG: there are 12-40 unaccounted-for massive haloes in the outskirts of the LG, a region that should be largely unaffected by any environmental processes. According to models that reproduce the LG stellar mass function, all of these missing massive systems should have M{sstarf} > 10⁶M_☉. We find, unexpectedly, that there is no obvious trend in the M_*-V_max relation for LG field galaxies with stellar masses in the range of ∼ 10⁵-10⁸M_☉. Solutions to the too big to fail problem that rely on ram pressure stripping, tidal effects, or statistical flukes appear less likely in the face of these results.