The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution.

The rotation curve (RC) of the Milky Way out to ~100 kpc has been constructed using ~16 000 primary red clump giants (PRCGs) in the outer disc selected from the LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC) and the Sloan Digital Sky Survey (SDSS)-III/APOGEE survey, combined with ~5700 halo K giants (HKGs) selected from the SDSS/SEGUE survey. To derive the RC, the PRCG sample of the warm disc population and the HKG sample of halo stellar population are, respectively, analysed using a kinematical model allowing for the asymmetric drift corrections and re-analysed using the spherical Jeans equation along with measurements of the anisotropic parameter β currently available. The typical uncertainties of RC derived from the PRCG and HKG samples are, respectively, 5- 7 km s-1 and several tens km s-1.We determine a circular velocity at the solar position, Vc(R0) = 240 ± 6 km s-1 and an azimuthal peculiar speed of the Sun, V☉ = 12.1 ± 7.6 km s-1, both in good agreement with the previous determinations. The newly constructed RC has a generally flat value of 240 km s-1 within a Galactocentric distance r of 25 kpc and then decreases steadily to 150 km s-1 at r ~ 100 kpc. On top of this overall trend, the RC exhibits two prominent localized dips, one at r ~11 kpc and another at r ~ 19 kpc. From the newly constructed RC, combined with other constraints, we have built a parametrized mass model for the Galaxy, yielding a virial mass of the MilkyWay's dark matter halo of 0.90+0.07 -0.08 × 1012 M☉ and a local dark matter density, ρ☉,dm = 0.32+0.02 -0.02 GeV cm-3. [ABSTRACT FROM AUTHOR]