Abstract

We use high-resolution N-body simulations to study the effect of a galactic disc on the dynamical evolution of dark matter substructures with orbits and structural parameters extracted from the Aquarius A-2 merger tree. Satellites are modelled as equilibrium N-body realizations of generalized Hernquist profiles with 2 x 10(6) particles and injected in the analytical evolving host potential at zinfall, defined by the peak of their mass evolution. We select all substructures with M-200(z(infall)) = 10(8)M(circle dot) and first pericentric distances r(p) r(200). Motivated by observations of Milky Way dwarf spheroidal galaxies, we also explore satellite models with cored dark matter profiles with a fixed core size r(c) = 0.8 a(s), where a(s) is the Hernquist scale radius. We find that models with cuspy satellites have twice as many surviving substructures at z = 0 than their cored counterparts, and four times as many if we only consider those on orbits with r(p) less than or similar to 0.1 r(200). For a given profile, adding an evolving disc potential reduces the number of surviving substructures further by a factor of less than or similar to 2 for satellites on orbits which penetrate the disc (r(p) less than or similar to 20 kpc). For large r(p), where tidal forces and the effect of the disc become negligible, the number of satellites per pericentre bin converges to similar values for all four models.