The effect of a disc on the population of cuspy and cored dark matter substructures in Milky Way-like galaxies

Raphaël Errani; Jorge Peñarrubia; Chervin F. P. Laporte; Facundo A. Gómez

doi:10.1093/mnrasl/slw211

paper

The effect of a disc on the population of cuspy and cored dark matter substructures in Milky Way-like galaxies

arXiv:1608.01849 · doi:10.1093/mnrasl/slw211

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 (Springel et al. 2008). Satellites are modelled as equilibrium $N$ -body realizations of generalized Hernquist profiles with $2 \times 1 0^{6}$ particles and injected in the analytical evolving host potential at $z_{infall}$ , defined by the peak of their mass evolution. We select all substructures with $M_{200} (z_{infall}) \geq 1 0^{8} M_{⊙}$ 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 $r_{p} ≲ 0.1 r_{200}$ . For a given profile, adding an evolving disc potential reduces the number of surviving substructures further by a factor of $≲ 2$ for satellites on orbits that penetrate the disc ( $r_{p} ≲ 20 kpc$ ). 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.

5 pages, 3 figures

The effect of a disc on the population of cuspy and cored dark matter substructures in Milky Way-like galaxies

Abstract

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