Too small to succeed? Lighting up massive dark matter subhaloes of the
  Milky Way
  Using Constrained Local UniversE Simulations (CLUES) of the formation of the
Local Group in a cosmological context we investigate the recently highlighted
problem that the majority of the most massive dark subhaloes of the Milky Way
are too dense to host any of its bright satellites. In particular, we examine
the influence of baryonic processes and find that they leave a twofold effect
on the relation between the peak of the rotation curve and its position (Vmax
and Rmax). Satellites with a large baryon fraction experience adiabatic
contraction thus decreasing Rmax while leaving Vmax more or less unchanged.
Subhaloes with smaller baryon fractions undergo a decrease in Vmax possibly due
to outflows of material. Furthermore, the situation of finding subhaloes in
simulations that lie outside the confidence interval for possible hosts of the
bright MW dwarf spheroidals, appears to be far more prominent in cosmologies
with a high sigma8 normalisation and depends on the mass of the host. We
conclude that the problem cannot be simply solved by including baryonic
processes and hence demands further investigations.
