Cusp-core transformations in dwarf galaxies: observational predictions
  The presence of a dark matter core in the central kiloparsec of many dwarf
galaxies has been a long standing problem in galaxy formation theories based on
the standard cold dark matter paradigm. Recent cosmological simulations, based
on Smooth Particle Hydrodynamics and rather strong feedback recipes have shown
that it was indeed possible to form extended dark matter cores using baryonic
processes related to a more realistic treatment of the interstellar medium.
Using adaptive mesh refinement, together with a new, stronger supernovae
feedback scheme that we have recently implemented in the RAMSES code, we show
that it is also possible to form a prominent dark matter core within the
well-controlled framework of an isolated, initially cuspy, 10 billion solar
masses dark matter halo. Although our numerical experiment is idealized, it
allows a clean and unambiguous identification of the dark matter core formation
process. Our dark matter inner profile is well fitted by a pseudo-isothermal
profile with a core radius of 800 pc. The core formation mechanism is
consistent with the one proposed recently by Pontzen & Governato. We highlight
two key observational predictions of all simulations that find cusp-core
transformations: (i) a bursty star formation history with peak to trough ratio
of 5 to 10 and a duty cycle comparable to the local dynamical time; and (ii) a
stellar distribution that is hot with v/sigma=1. We compare the observational
properties of our model galaxy with recent measurements of the isolated dwarf
WLM. We show that the spatial and kinematical distribution of stars and HI gas
are in striking agreement with observations, supporting the fundamental role
played by stellar feedback in shaping both the stellar and dark matter
distribution.
