Title:Under the sword of Damocles: regeneration of dark matter cusps at the smallest galactic 
scales in CDM

Abstract:
Baryonic feedback at high redshifts has been proposed to explain the inference of dark matter 
(DM) cores in low-surface brightness and dwarf spheroidal galaxies. However, our currently 
favoured cosmological LCDM model, predicts a myriad of small substructures orbiting dwarf 
galaxies, some luminous, some dark. If such halos get close enough to the centre of cored 
dwarfs, they could potentially lead to cusp regrowth.

In this talk, I will present the evolution of the DM profiles of dwarf galaxies driven by the 
accretion of DM substructures through controlled N-body experiments. The initial conditions 
assume that supernova feedback erases the primordial DM cusps at high redshift of halos with 
final masses $10^{9}-10^{10} \rm{M_{\odot}}$ by z=0. The orbits and masses of the infalling 
substructures are borrowed from the {\it Aquarius} cosmological simulations. I will show that 
some halos that undergo 1:3 down to 1:30 mergers are susceptible to reform a DM cusp by $z
\approx 0$ and how this depends on the internal structure of the infalling substructures. I will 
show that within CDM a non-negligible level of scatter in the mass profiles of dwarfs is to be 
expected given their stochastic mass accretion histories and their diverse (observed) star 
formation histories and that this effect could  possibly explain the existence of dense dwarfs like 
Draco, Ursa Minor or Tucana. I will argue how this process is unique to CDM and may be 
distinguishable from other DM models and will show preliminary results from suites of 
cosmological N-body simulations designed to address the statistics of this effect.