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Identifying true satellites of the Magellanic Clouds

Sales, L.V.; Navarro, J.F.; Kallivayalil, N.; Frenk, C.S.

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L.V. Sales

J.F. Navarro

N. Kallivayalil


The hierarchical nature of ΛCDM suggests that the Magellanic Clouds must have been surrounded by a number of satellites before their infall into the Milky Way halo. Many of those satellites should still be in close proximity to the Clouds, but some could have dispersed ahead/behind the Clouds along their Galactic orbit. Either way, prior association with the Clouds constrains the present-day positions and velocities of candidate Magellanic satellites: they must lie close to the nearly polar orbital plane of the Magellanic Stream, and their distances and radial velocities must follow the latitude dependence expected for a tidal stream with the Clouds near pericentre. We use a cosmological numerical simulation of the disruption of a massive sub-halo in a Milky Way-sized ΛCDM halo to test whether any of the 20 dwarfs recently discovered in the Dark Energy Survey, the Survey of the MAgellanic Stellar History, Pan-STARRS, and ATLAS surveys are truly associated with the Clouds. Of the six systems with kinematic data, only Hor 1 has distance and radial velocities consistent with a Magellanic origin. Of the remaining dwarfs, six (Hor 2, Eri 3, Ret 3, Tuc 4, Tuc 5, and Phx 2) have positions and distances consistent with a Magellanic origin, but kinematic data are needed to substantiate that possibility. Conclusive evidence for association would require proper motions to constrain the orbital angular momentum direction, which, for true Magellanic satellites, must be similar to that of the Clouds. We use this result to predict radial velocities and proper motions for all new dwarfs, assuming that they were Magellanic satellites. Our results are relatively insensitive to the assumption of first or second pericentre for the Clouds


Sales, L., Navarro, J., Kallivayalil, N., & Frenk, C. (2017). Identifying true satellites of the Magellanic Clouds. Monthly Notices of the Royal Astronomical Society, 465(2), 1879-188.

Journal Article Type Article
Acceptance Date Oct 31, 2016
Online Publication Date Nov 2, 2016
Publication Date Feb 21, 2017
Deposit Date Feb 27, 2017
Publicly Available Date Mar 2, 2017
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 465
Issue 2
Pages 1879-188


Published Journal Article (1.5 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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