Binary Satellite Galaxies

Abstract

Suggestions have appeared in the literature that the following five pairs of Milky Way and Andromeda satellite galaxies are gravitationally bound: Draco and Ursa Minor, Leo IV and V, Andromeda I and III, NGC 147 and 185, and the Magellanic clouds. Under the assumption that a given pair is gravitationally bound, the Virial theorem provides an estimate of its total mass and so its instantaneous tidal radius. For all of these pairs except for the Magellanic clouds the resulting total mass is 2 to 4 orders of magnitude higher than that within the half light radius. Furthermore in the case of each pair except for Leo IV and Leo V, the estimated tidal radius is inferior to the separation between the two satellites. Therefore all or almost all of these systems are not gravitationally bound. We note several possible explanations for the proximities and similar radial velocities of the satellites in each pair, for example they may have condensed from the same infalling structure or they may be bound by a nongravitational interaction between dark matter and an extremely light particle.

21 pages, 7 jpg figures

References in corpus (14)

• Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5
• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies
• Is the SMC Bound to the LMC? The HST Proper Motion of the SMC
• Dwarf Galaxy Planes: the discovery of symmetric structures in the Local Group
• The rotationally stabilized VPOS and predicted proper motions of the Milky Way satellite galaxies
• Leo V: A Companion of a Companion of the Milky Way Galaxy
• Galactic Archaeology. The dwarfs that survived and perished
• The Dynamics of Galaxy Pairs in a Cosmological Setting
• Galaxy And Mass Assembly (GAMA): In Search of Milky-Way Magellanic Cloud Analogues
• Detecting Dark Matter Substructures around the Milky Way with Gaia
• Dwarfs walking in a row. The filamentary nature of the NGC3109 association
• The Origin of Large-scale HI structures in the Magellanic Bridge
• Dwarf Galaxy Sized Monopoles as Dark Matter?

Cited by in corpus (9)

• Discovery of a close pair of faint dwarf galaxies in the halo of Centaurus A
• Ships Passing in the Night: Spectroscopic Analysis of Two Ultra-Faint Satellites in the Constellation Carina
• A PAndAS view of M31 dwarf elliptical satellites: NGC147 and NGC185
• Portrait of a Dark Horse: a Photometric and Spectroscopic Study of the Ultra-faint Milky Way Satellite Pegasus III
• GASS 3505: the prototype of HI-excess, passive galaxies
• A multiwavelength survey of HI-excess galaxies with surprisingly inefficient star formation
• The potential role of NGC 205 in generating Andromeda's vast thin co-rotating plane of satellite galaxies
• The interstellar medium in Andromeda's dwarf spheroidal galaxies: II. Multi-phase gas content and ISM conditions
• Testing a proposed "planarity" tool for studying satellite systems: On the alleged consistency of Milky Way satellite galaxy planes with $\Lambda$CDM