摘要：We measure the escape speed curve of the Milky Way based on the analysis of the velocity distribution of ~2850 counter-rotating halo stars from theGaiaData Release 2. The distances were estimated through theStarHorsecode, and only stars with distance errors smaller than 10% were used in the study. The escape speed curve is measured at Galactocentric radii ranging from ~5 kpc to ~10.5 kpc. The local Galactic escape at the Sun’s position is estimated to beve(r⊙) = 580 ± 63 km s−1, and it rises towards the Galactic centre. Defined as the minimum speed required to reach three virial radii, our estimate of the escape speed as a function of radius implies for a Navarro–Frenk–White profile and local circular velocity of 240 km s−1a dark matter massM200 = 1.28−0.50+0.68 × 1012 M⊙and a high concentrationc200 = 11.09−1.79+2.94. Assuming the mass-concentration relation of ΛCDM, we obtainM200 = 1.55−0.51+0.64 × 1012 M⊙andc200 = 7.93−0.27+0.33for a local circular velocity of 228 km s−1.
关键词：enGalaxy: kinematics and dynamicsGalaxy: fundamental parameters
