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The low abundance and insignificance of dark discs in simulated Milky Way galaxies

Schaller, Matthieu; Frenk, Carlos S.; Fattahi, Azadeh; Navarro, Julio F.; Oman, Kyle A.; Sawala, Till

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Authors

Azadeh Fattahi

Julio F. Navarro

Kyle A. Oman

Till Sawala



Abstract

We investigate the presence and importance of dark matter discs in a sample of 24 simulated Milky Way galaxies in the apostle project, part of the eagle programme of hydrodynamic simulations in ΛCDM cosmology. It has been suggested that a dark disc in the Milky Way may boost the dark matter density and modify the velocity modulus relative to a smooth halo at the position of the Sun, with ramifications for direct detection experiments. From a kinematic decomposition of the dark matter and a real space analysis of all 24 haloes, we find that only one of the simulated Milky Way analogues has a detectable dark disc component. This unique event was caused by a merger at late time with an LMC-mass satellite at very low grazing angle. Considering that even this rare scenario only enhances the dark matter density at the solar radius by 35 per cent and affects the high-energy tail of the dark matter velocity distribution by less than 1 per cent, we conclude that the presence of a dark disc in the Milky Way is unlikely, and is very unlikely to have a significant effect on direct detection experiments.

Citation

Schaller, M., Frenk, C. S., Fattahi, A., Navarro, J. F., Oman, K. A., & Sawala, T. (2016). The low abundance and insignificance of dark discs in simulated Milky Way galaxies. Monthly Notices of the Royal Astronomical Society: Letters, 461(1), L56-L61. https://doi.org/10.1093/mnrasl/slw101

Journal Article Type Article
Acceptance Date May 12, 2016
Online Publication Date May 16, 2016
Publication Date Sep 1, 2016
Deposit Date Aug 15, 2016
Publicly Available Date Aug 15, 2016
Journal Monthly Notices of the Royal Astronomical Society: Letters
Electronic ISSN 1745-3933
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 461
Issue 1
Pages L56-L61
DOI https://doi.org/10.1093/mnrasl/slw101
Related Public URLs http://arxiv.org/abs/1605.02770

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





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