The Milky Way’s Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from the Kinematics of ∼2400 SDSS Blue Horizontal‐Branch Stars

We derive new constraints on the mass of the Milky Way's dark matter halo, based on 2401 rigorously selected blue horizontal-branch halo stars from SDSS DR6. This sample enables construction of the full line-of-sight velocity distribution at different galactocentric radii. To interpret these distributions, we compare them to matched mock observations drawn from two different cosmological galaxy formation simulations designed to resemble the Milky Way. This procedure results in an estimate of the Milky Way's circular velocity curve to ~60 kpc, which is found to be slightly falling from the adopted value of 220 km s-1 at the Sun's location, and implies M(<60 kpc)=(4.0+/-0.7)×1011 Msolar. The radial…

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  Science and Technology Facilities Council

  Award: PP/E00105X/1