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The mass of the Milky Way out to 100 kpc using halo stars

Deason, Alis J; Erkal, Denis; Belokurov, Vasily; Fattahi, Azadeh; Gómez, Facundo A; Grand, Robert JJ; Pakmor, Rüdiger; Xue, Xiang-Xiang; Liu, Chao; Yang, Chengqun; Zhang, Lan; Zhao, Gang

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Authors

Denis Erkal

Vasily Belokurov

Facundo A Gómez

Robert JJ Grand

Rüdiger Pakmor

Xiang-Xiang Xue

Chao Liu

Chengqun Yang

Lan Zhang

Gang Zhao



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 (⁠∼98 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.) × 1011 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 M200c = 1.01 ± 0.24 × 1012 M⊙, or (post-LMC infall) mass of M200c = 1.16 ± 0.24 × 1012 M⊙ when a 1.5 × 1011 M⊙ mass of a rigid LMC is included.

Citation

Deason, A. J., Erkal, D., Belokurov, V., Fattahi, A., Gómez, F. A., Grand, R. J., …Zhao, G. (2021). The mass of the Milky Way out to 100 kpc using halo stars. Monthly Notices of the Royal Astronomical Society, 501(4), 5964-5972. https://doi.org/10.1093/mnras/staa3984

Journal Article Type Article
Acceptance Date Dec 21, 2020
Online Publication Date Dec 28, 2020
Publication Date 2021-03
Deposit Date Jul 2, 2021
Publicly Available Date Jul 2, 2021
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 501
Issue 4
Pages 5964-5972
DOI https://doi.org/10.1093/mnras/staa3984

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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