mass of the Local Group of several $10^{12}\Msun$. Sawa and Fujimoto (2005) have computed probable past orbits of almost all major members of the Local Group under the condition that their positions and radial velocities are satisfied at the present time. They suggested a great encounter of the Galaxy and M31 group in the past. Cox and Loeb (2008) predict a future collision again of the Galaxy with M31.

In the present paper, we examine the behaviors of rotation curves calculated for different dark halo models in the outskirts of the Galaxy and in the Local Group. We compare the model rotation curves with a “pseudo rotation curve” of the Local Group, which combines the rotation curve of the Galaxy and radial velocities of the members of the Local Group.

Galactic Rotation Curve
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![Schematic rotation curves of the Galaxy for three dark halo models: isothermal, Burkert and NFW dark halo models, by solid lines from top to bottom at $R=30$ kpc. Lower curves show rotation velocities due to dark halos alone, and upper curves are for those including the bulge and disk. The inner and outer dashed lines are for the bulge and disk components, respectively. []{data-label="fig-rcmodels"}](fig-rho.eps "fig:"){width="8cm"}\

![Schematic 