Constraining the Milky Way halo potential with the GD-1 stellar stream. Issue 3 (13th April 2019)

• Record Type: Journal Article
• Authors: Malhan, Khyati; Ibata, Rodrigo A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 486:Issue 3(2019)
• Page Start: 2995
• Page End: 3005
• Publication Date: 2019-04-13
• Subjects: stars: kinematics and dynamics -- Galaxy: fundamental parameters -- Galaxy: halo -- Galaxy: structure -- dark matter; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz1035
• Languages: English
• ISSNs: 0035-8711

Abstract

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 $V_{\rm circ}({\rm R}_\odot) =244\pm 4{\rm \, km\, s^{-1}}$, and also that the density flattening of the dark halo is $q_{\rho }=0.82^{+0.25}_{-0.13}$ . The corresponding Galactic mass within $20{\rm \, kpc}$ was estimated to be $M_{\rm MW}(\lt 20{\rm \, kpc})=2.5\pm 0.2 \times 10^{11} {\rm \, M_\odot }$ . 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 $\lt 2.30{\rm \, km\, s^{-1}}$ (95 per cent confidence limit), confirming the extremely cold dynamical nature of this system.