Comparing galactic satellite properties in hydrodynamical and Nbody
  simulations
  In this work, we examine the different properties of galactic satellites in
hydrodynamical and pure dark matter simulations. We use three pairs of
simulations (collisional and collision-less) starting from identical initial
conditions. We concentrate our analysis on pairs of satellites in the hydro and
Nbody runs that form from the same Lagrangian region. We look at the radial
positions, mass loss as a function of time and orbital parameters of these
"twin" satellites. We confirm an overall higher radial density of satellites in
the hydrodynamical runs, but find that trends in the mass loss and radial
position of these satellites in the inner and outer region of the parent halo
differ from the pure dark matter case. In the outskirts of the halo (~70% of
the virial radius) satellites experience a stronger mass loss and higher
dynamical friction in pure dark matter runs. The situation is reversed in the
central region of the halo, where hydrodynamical satellites have smaller
apocenter distances and suffer higher mass stripping. We partially ascribe this
bimodal behaviour to the delayed infall time for hydro satellites, which on
average cross the virial radius of the parent halo 0.7 Gyrs after their dark
matter twins. Finally, we briefly discuss the implications of the different set
of satellite orbital parameters and mass loss rates in hydrodynamical
simulations within the context of thin discs heating and destruction.
