The Local Group as a test system for Modified Newtonian Dynamics

Abstract

The Local Group (LG) is {an appropriate} test system for Modified Newtonian Dynamics, since the acceleration of M31 galaxy is fully in the deep MOND regime $a\ll a_0$. We model the LG as a two body problem of $M31$ and the Milky Way (MW) galaxies. {Extending previous studies, we also include the Cosmological Constant.} The assumption that in the big bang the galaxies emerged from the same place and approach to the measured distance and velocity today (the Timing Argument), predicts the total mass for the LG: $(0.447\pm 0.005)\cdot 10^{12}{M}_{\odot }$. The corresponding motion of the LG predicts a past encounter. The ratio between the baryonic mass that MOND considers to the mass that Newtonian case predicted, which includes dark matter is $10.74\pm 0.82$. This ratio agrees with the ratio between the dark matter and baryonic matter in other galaxies.

7 pages; 5 figures

References in corpus (8)

• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• The M31 Velocity Vector. II. Radial Orbit Towards the Milky Way and Implied Local Group Mass
• The Structures of Distant Galaxies - III: The Merger History of over 20,000 Massive Galaxies at z < 1.2
• A dynamical model of the local cosmic expansion
• The Collision Between The Milky Way And Andromeda
• Dynamics of astrophysical objects against the cosmological background
• Hubble flows and gravitational potentials in observable Universe
• Constraining the mass of the Local Group