The Imprint of Spiral Arms on the Galactic Rotation Curve

We apply the radial acceleration relation to the terminal velocities of the Milky Way to obtain the corresponding stellar surface density profile. This profile contains bumps and wiggles that correspond to massive spiral arms. These features impact the term for the logarithmic density gradient in the Jeans equation in a way that reconciles the apparent discrepancy between the stellar rotation curve ascertained from Gaia data and the terminal velocity curve traced by interstellar gas. Indeed, this approach correctly predicted the gradually declining rotation curve outside the solar circle (dV/dR = -1.7 km/s/kpc) in advance of its observation.