The infall of dwarf satellite galaxies are influenced by their host's massive accretions

Understand

Recent progress in constraining the massive accretions (>1:10) experienced by the Milky Way (MW) and the Andromeda galaxy (M31) offers an opportunity to understand the dwarf galaxy population of the Local Group.

• Using zoom-in dark matter-only simulations of MW-mass haloes and concentrating on subhaloes that are thought to be capable of hosting dwarf galaxies, we demonstrate that the infall of a massive progenitor is accompanied with the accretion and destruction of a large number of subhaloes.
• Massive accreted progenitors do not increase the total number of infalling subhaloes onto a MW-mass host, but instead focus surrounding subhaloes onto the host causing a clustering in the infall time of subhaloes.
• This leads to a temporary elevation in the number of subhaloes as well as changes in their cumulative radial profile within the virial radius of the host.