Accurate Rotation Curves and Distribution of Dark Matter in Galaxies

Abstract

We present high-accuracy rotation curves, which show a steep nuclear rise and high-velocity central rotation, followed by a broad maximum in the disk and flat part. We use the rotation curves to directly calculate the radial distribution of surface mass density, and obtain radial variations of the mass-to-luminosity ratio (M/L). The M/L ratio and, therefore, the dark mass fraction (DMF) is not constant at all, but varies within the bulge, increases already within the disk, and rapidly from the disk toward halo. In some galaxies, the DMF within the bulge increases inward toward the center, indicating a massive dark core.