A Precise Milky Way Rotation Curve Model for an Accurate Galactocentric Distance

Abstract

I provide a model rotation curve for the Milky Way that matches the details of the terminal velocity curve normalized to the Galactocentric distance $R_0 = 8.122$ kpc obtained by the GRAVITY collaboration and the corresponding circular speed of the LSR $\Theta_0 = 233.3$ km/s. The model provides a numerical representation of the azimuthally averaged radial run of the gravitational potential of each mass component of the Galaxy (bulge-bar, stellar disk, gas disk, and dark matter) as represented by the rotation curve of each. It provides precise estimates of quantities like the stellar mass of the Galaxy ($6.16 \pm 0.31 \times 10^{10}\;\mathrm{M}_{\odot}$) and the local density of dark matter ($\rho_{DM}(R_0) = 6.76^{+0.08}_{-0.14} \times 10^{-3}\; \mathrm{M}_{\odot}\,\mathrm{pc}^{-3} = 0.257^{+0.003}_{-0.005}\; \mathrm{GeV}\,\mathrm{cm}^{-3}$). The dark matter density implied by the radial force is less than that found in many studies of the vertical force, perhaps indicating that the usual assumption of a spherical dark matter halo is no longer adequate.