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Detection of the LMC-induced sloshing of the Galactic halo

Erkal, Denis; Deason, Alis J; Belokurov, Vasily; Xue, Xiang-Xiang; Koposov, Sergey E; Bird, Sarah A; Liu, Chao; Simion, Iulia T; Yang, Chengqun; Zhang, Lan; Zhao, Gang

Detection of the LMC-induced sloshing of the Galactic halo Thumbnail


Authors

Denis Erkal

Vasily Belokurov

Xiang-Xiang Xue

Sergey E Koposov

Sarah A Bird

Chao Liu

Iulia T Simion

Chengqun Yang

Lan Zhang

Gang Zhao



Abstract

A wealth of recent studies have shown that the LMC is likely massive, with a halo mass >1011M⊙. One consequence of having such a nearby and massive neighbour is that the inner Milky Way is expected to be accelerated with respect to our Galaxy’s outskirts (beyond ∼30 kpc). In this work we compile a sample of ∼500 stars with radial velocities in the distant stellar halo, rGC > 50 kpc, to test this hypothesis. These stars span a large fraction of the sky and thus give a global view of the stellar halo. We find that stars in the Southern hemisphere are on average blueshifted, while stars in the North are redshifted, consistent with the expected, mostly downwards acceleration of the inner halo due to the LMC. We compare these results with simulations and find the signal is consistent with the infall of a 1.5 × 1011M⊙ LMC. We cross-match our stellar sample with Gaia DR2 and find that the mean proper motions are not yet precise enough to discern the LMC’s effect. Our results show that the Milky Way is significantly out of equilibrium and that the LMC has a substantial effect on our Galaxy.

Citation

Erkal, D., Deason, A. J., Belokurov, V., Xue, X., Koposov, S. E., Bird, S. A., …Zhao, G. (2021). Detection of the LMC-induced sloshing of the Galactic halo. Monthly Notices of the Royal Astronomical Society, 506(2), 2677-2684. https://doi.org/10.1093/mnras/stab1828

Journal Article Type Article
Acceptance Date Jun 24, 2021
Online Publication Date Jul 1, 2021
Publication Date 2021-09
Deposit Date Jul 14, 2021
Publicly Available Date Jul 14, 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 506
Issue 2
Pages 2677-2684
DOI https://doi.org/10.1093/mnras/stab1828

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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