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The mass of the Milky Way from satellite dynamics

Callingham, TM, Cautun, M, Deason, AJ, Frenk, CS, Wang, W, Gómez, FA, Grand, RJJ, Marinacci, F and Pakmor, R (2019) The mass of the Milky Way from satellite dynamics. Monthly Notices of the Royal Astronomical Society, 484 (4). pp. 5453-5467. ISSN 0035-8711

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We present and apply a method to infer the mass of the Milky Way (MW) by comparing the dynamics of MW satellites to those of model satellites in the EAGLE cosmological hydrodynamics simulations. A distribution function (DF) for galactic satellites is constructed from EAGLE using specific angular momentum and specific energy, which are scaled so as to be independent of host halo mass. In this two-dimensional space, the orbital properties of satellite galaxies vary according to the host halo mass. The halo mass can be inferred by calculating the likelihood that the observed satellite population is drawn from this DF. Our method is robustly calibrated on mock EAGLE systems. We validate it by applying it to the completely independent suite of 30 AURIGA high-resolution simulations of MW-like galaxies: the method accurately recovers their true mass and associated uncertainties. We then apply it to 10 classical satellites of the MW with six-dimensional phase-space measurements, including updated proper motions from the Gaia satellite. The mass of the MW is estimated to be M200MW = 1.17+0.21−0.15 × 1012 M (68 per cent confidence limits). We combine our total mass estimate with recent mass estimates in the inner regions of the Galaxy to infer an inner dark matter (DM) mass fraction MDM(< 20 kpc)/MDM200 = 0.12, which is typical of ∼1012 M lambda cold dark matter haloes in hydrodynamical galaxy formation simulations. Assuming a Navarro, Frenk and White (NFW) profile, this is equivalent to a halo concentration of c200MW = 10.9+2.6−2.0

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press (OUP)
SWORD Depositor: A Symplectic
Date Deposited: 19 Apr 2023 11:45
Last Modified: 19 Apr 2023 11:45
DOI or ID number: 10.1093/mnras/stz365
URI: https://researchonline.ljmu.ac.uk/id/eprint/19326
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