The mass of the Milky Way out to 100 kpc using halo stars. Issue 4 (28th December 2020)

• Record Type: Journal Article
• Authors: Deason, Alis J; Erkal, Denis; Belokurov, Vasily; Fattahi, Azadeh; Gómez, Facundo A; Grand, Robert J J; Pakmor, Rüdiger; Xue, Xiang-Xiang; Liu, Chao; Yang, Chengqun; Zhang, Lan; Zhao, Gang
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 501:Issue 4(2021)
• Page Start: 5964
• Page End: 5972
• Publication Date: 2020-12-28
• Subjects: Galaxy: halo -- Galaxy: kinematics and dynamics -- Local Group; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3984
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We use a distribution function analysis to estimate the mass of the Milky Way (MW) out to 100 kpc using a large sample of halo stars. These stars are compiled from the literature, and the vast majority (${\sim } 98{{\ \rm per\ cent}}$ ) have 6D phase-space information. We pay particular attention to systematic effects, such as the dynamical influence of the Large Magellanic Cloud (LMC), and the effect of unrelaxed substructure. The LMC biases the (pre-LMC infall) halo mass estimates towards higher values, while realistic stellar haloes from cosmological simulations tend to underestimate the true halo mass. After applying our method to the MW data, we find a mass within 100 kpc of M (<100 kpc) = 6.07 ± 0.29 (stat.) ± 1.21 (sys.) × 10 11 M⊙ . For this estimate, we have approximately corrected for the reflex motion induced by the LMC using the Erkal et al. model, which assumes a rigid potential for the LMC and MW. Furthermore, stars that likely belong to the Sagittarius stream are removed, and we include a 5 per cent systematic bias, and a 20 per cent systematic uncertainty based on our tests with cosmological simulations. Assuming the mass–concentration relation for Navarro–Frenk–White haloes, our mass estimate favours a total (pre-LMC infall) MW mass of M 200c = 1.01 ± 0.24 × 10 12 M⊙, or (post-LMC infall) mass of M 200c = 1.16 ± 0.24 × 10 12 M⊙ when a 1.5 × 10 11 M⊙ mass of a rigid LMC is included.