$V_{\rm d} (R)$, and $V_{\rm h} (R)$ are the circular velocity corresponding to individual components of the bulge, disk, and dark halo, respectively. Figure \[fig-rcmodels\] shows the calculated rotation curves for the bulge, disk and halo as well as their sum, for the three isothermal, NFW and Burkert halo models. The calculated rotation curve may be typical for a spiral galaxy having the standard structure, and mimics those obtained for M31 and other disk galaxies (Carignan et al. 2006; Hayashi and Chiba 2006). Rotation curves based on NFW density profiles have been obtained for various types of galaxies (Seljak 2002).

![image](fig-rc30.eps){width="15cm"}\

Figure \[fig-rc30\] shows the observed rotation curve of the Galaxy reproduced from Sofue et al. (2008), which is a compilation of observations in the decades from HI, CO, optical and VERA measurements. The observations are well fitted by a model rotation curve by the grey line (Sofue et al. 2008), which can be decomposed into three components: a de Vaucouleurs bulge of mass $M_{\rm b} =1.8 \times 10^{10}\Msun$ and scale radius $R_{\rm b} =0.5$ kpc, an exponential disk of mass $M_{\rm d} =7 \times 10^{10}\Msun$ and scale radius $R_{\rm d} =3.5 $ kpc, and an isothermal dark halo of 