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The velocity anisotropy of the Milky Way satellite system

Riley, AH, Fattahi, A, Pace, AB, Strigari, LE, Frenk, CS, Gómez, FA, Grand, RJJ, Marinacci, F, Navarro, JF, Pakmor, R, Simpson, CM and White, SDM (2019) The velocity anisotropy of the Milky Way satellite system. Monthly Notices of the Royal Astronomical Society, 486 (2). pp. 2679-2694. ISSN 0035-8711

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We analyse the orbital kinematics of the Milky Way (MW) satellite system utilizing the latest systemic proper motions for 38 satellites based on data from Gaia Data Release 2. Combining these data with distance and line-of-sight velocity measurements from the literature, we use a likelihood method to model the velocity anisotropy, β, as a function of Galactocentric distance and compare the MW satellite system with those of simulated MW-mass haloes from the APOSTLE (A Project Of Simulating The Local Environment) and Auriga simulation suites. The anisotropy profile for the MW satellite system increases from β ∼-2 at r∼20 kpc to β ∼0.5 at r∼200 kpc, indicating that satellites closer to the Galactic centre have tangentially biased motions while those farther out have radially biased motions. The motions of satellites around APOSTLE host galaxies are nearly isotropic at all radii, while the β(r) profiles for satellite systems in the Auriga suite, whose host galaxies are substantially more massive in baryons than those inAPOSTLE, aremore consistent with that of theMWsatellite system. This shape of the β(r) profile may be attributed to the central stellar disc preferentially destroying satellites on radial orbits, or intrinsic processes from the formation of the MW system.

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 11:47
Last Modified: 19 Apr 2023 11:47
DOI or ID number: 10.1093/mnras/stz973
URI: https://researchonline.ljmu.ac.uk/id/eprint/19324
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