On Asymmetric Distributions of Satellite Galaxies

Abstract

We demonstrate that the asymmetric distribution of M31 satellites cannot be produced by tides from the Milky Way as such effects are too weak. However, loosely bound associations and groups of satellites can fall into larger haloes and give rise to asymmetries. We compute the survival times for such associations. We prove that the survival time is always shortest in Keplerian potentials, and can be ~ 3 times longer in logarithmic potentials. We provide an analytical formula for the dispersal time in terms of the size and velocity dispersion of the infalling structure. We show that, if an association of ~10 dwarfs fell into the M31 halo, its present aspect would be that of an asymmetric disk of satellites. We also discuss the case of cold substructure in the Andromeda II and Ursa Minor dwarfs.

5 pages, 2 figures, Ap J (Letters), in press

References in corpus (6)

• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• Small Dwarf Galaxies Within Larger Dwarfs: Why Some Are Luminous While Most Go Dark
• Associations of Dwarf Galaxies
• Infall of substructures onto a Milky Way-like dark halo
• Balancing mass and momentum in the Local Group
• Hamiltonians of Spherically Symmetric, Scale-Free Galaxies in Action-Angle Coordinates

Cited by in corpus (5)

• Beasts of the Southern Wild: Discovery of nine Ultra Faint satellites in the vicinity of the Magellanic Clouds
• On feathers, bifurcations and shells: the dynamics of tidal streams across the mass scale
• The Origin of Lopsided Satellite Galaxy Distribution in Galaxy Pairs
• The shapes and alignments of the satellites of the Milky Way and Andromeda
• Is there substructure around M87?