ALBERT

Description: 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, V c ( R 0 ) = 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 Milky Way's dark matter halo of $0.90^{+0.07}_{-0.08} \times 10^{12}$  M and a local dark matter density, $\rho _{\rm {\odot }, dm} = 0.32^{+0.02}_{-0.02}$  GeV cm –3 .