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.

arXiv comment5 pages, 2 figures, Ap J (Letters), in press

References in corpus (17)

• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• A Dynamical Fossil in the Ursa Minor Dwarf Spheroidal 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
• The Three-Dimensional Structure of the M31 Satellite System; Strong Evidence for an Inhomogeneous Distribution of Satellites
• The preferred direction of infalling satellite galaxies in the Local Group
• The Mass of the Andromeda Galaxy
• The satellite distribution of M31
• Stream-orbit misalignment I: The dangers of orbit-fitting
• The remnant of a merger between two dwarf galaxies in Andromeda II
• The Formation of the Local Group Planes of Galaxies
• Balancing mass and momentum in the Local Group
• A comparison of the distribution of satellite galaxies around Andromeda and the results of $\Lambda$CDM simulations
• A single-merger scenario for the formation of the giant stream and the warp of M31
• Triaxial Cosmological Haloes and the Disc of Satellites
• Hamiltonians of Spherically Symmetric, Scale-Free Galaxies in Action-Angle Coordinates

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• Small scale problems of the $\Lambda$CDM model: a short review
• A Magellanic Origin of the DES Dwarfs
• On feathers, bifurcations and shells: the dynamics of tidal streams across the mass scale
• Local ultra faint dwarves as a product of Galactic processing during a Magellanic group infall
• The Origin of Lopsided Satellite Galaxy Distribution in Galaxy Pairs
• The shape alignment of satellite galaxies in galaxy pairs in SDSS
• The shapes and alignments of the satellites of the Milky Way and Andromeda
• On the origin of the asymmetric dwarf galaxy distribution around Andromeda
• Is there substructure around M87?
• Andromeda's asymmetric satellite system as a challenge to cold dark matter cosmology