A dynamical model of the local cosmic expansion

  title={A dynamical model of the local cosmic expansion},
  author={Jorge Pe{\~n}arrubia and Yin-Zhe Ma and Matthew G. Walker and Alan W. McConnachie},
  journal={Monthly Notices of the Royal Astronomical Society},
We combine the equations of motion that govern the dynamics of galaxies in the local volume with Bayesian techniques in order to fit orbits to published distances and velocities of galaxies within $\sim 3$ Mpc. We find a Local Group (LG) mass $2.3\pm 0.7\times 10^{12}{\rm M}_\odot$ that is consistent with the combined dynamical masses of M31 and the Milky Way, and a mass ratio $0.54^{+0.23}_{-0.17}$ that rules out models where our Galaxy is more massive than M31 with $\sim 95\%$ confidence. The… 

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