Constraining the Milky Way halo potential with the GD-1 stellar stream
Abstract
We use ESA/Gaia astrometry together with SEGUE and LAMOST measurements of the GD-1 stellar stream to explore the improvement on the Galactic gravitational potential that these new data provide. Assuming a realistic universal model for the dark matter halo together with reasonable models of the baryonic components, we find that the orbital solutions for GD-1 require the circular velocity at the Solar radius to be V_circ(R_⊙) =244± 4{ km s^{-1}}, and also that the density flattening of the dark halo is q_{ρ }=0.82^{+0.25}_{-0.13}. The corresponding Galactic mass within 20{ kpc} was estimated to be M_MW(< 20{ kpc})=2.5± 0.2 × 10^{11} { M_⊙}. Moreover, Gaia's excellent proper motions also allowed us to constrain the velocity dispersion of the GD-1 stream in the direction tangential to the line of sight to be < 2.30{ km s^{-1}} (95 per cent confidence limit), confirming the extremely cold dynamical nature of this system.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 2019
- DOI:
- 10.1093/mnras/stz1035
- arXiv:
- arXiv:1807.05994
- Bibcode:
- 2019MNRAS.486.2995M
- Keywords:
-
- stars: kinematics and dynamics;
- Galaxy: fundamental parameters;
- Galaxy: halo;
- Galaxy: structure;
- dark matter;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 8 Figures, 2 Tables, accepted by MNRAS