A Dynamical Model of the Local Group

Abstract

This dynamical model for the 28 galaxies with distances less than 1.5 Mpc, and not apparently tight satellites, is constrained by the initial condition that peculiar velocities at high redshift are small and growing in accordance with the standard cosmology. The solution is a satisfactory fit to most of the measured redshifts, distances, and proper motions, with some interesting exceptions that call for further investigation. The model predicts Milky Way rotation speed 256 km/s, consistent with Reid et al. (2009a). Ten Local Group galaxies emanate from low supergalactic latitude and supergalactic longitude ~ 70 degrees, perhaps as remnants from failed assembly of a larger galaxy. NGC 6822 passes close to the Milky Way at redshift ~0.27, in an orbit similar to the Magellanic Clouds. Leo I has heliocentric angular velocity 0.33 mas/yr, perhaps measurable by the mean stellar motion, and 15 galaxies have proper motions greater than 0.05 mas/yr, measurable for any with masers.

27 pages, 7 figures

References in corpus (2)

• PAndAS' progeny: extending the M31 dwarf galaxy cabal
• Motions of Galaxies in the Local Group and Beyond: an Astro2010 Science White Paper

Cited by in corpus (14)

• The APOSTLE project: Local Group kinematic mass constraints and simulation candidate selection
• An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
• The M31 Velocity Vector. III. Future Milky Way-M31-M33 Orbital Evolution, Merging, and Fate of the Sun
• Simulated Milky Way analogues: implications for dark matter indirect searches
• Balancing mass and momentum in the Local Group
• A Plane of High Velocity Galaxies Across the Local Group
• Gas Accretion onto the Milky Way
• "Dark energy" in the Local Void
• Dynamical History Of The Local Group In $\Lambda$CDM $\mathrm{II}$ $-$ Including External Perturbers In 3D
• Dynamics of the Local Group: the Dwarf Galaxies
• The Variety of Solutions for Dynamics in the Local Group
• A Primeval Magellanic Stream and Others
• Distinguishing Standard from Modified Gravity in the Local Group and beyond
• Dynamics of the Local Group: the Outer Galactic Globular Star Clusters