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

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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 , vol. 461 , no. 1 , pp. L56-L61 . DOI: 10.1093/mnrasl/slw101

Title: The low abundance and insignificance of dark discs in simulated Milky Way galaxies
Author: Schaller, Matthieu; Frenk, Carlos S.; Fattahi, Azadeh; Navarro, Julio F.; Oman, Kyle A.; Sawala, Till
Contributor: University of Helsinki, Particle Physics and Astrophysics
Date: 2016-09-01
Language: eng
Number of pages: 6
Belongs to series: Monthly Notices of the Royal Astronomical Society
ISSN: 0035-8711
URI: http://hdl.handle.net/10138/183972
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 Lambda CDM 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.
Subject: methods: numerical
Galaxy: disc
Galaxy: structure
cosmology: theory
dark matter
COSMOLOGICAL SIMULATIONS
ANGULAR-MOMENTUM
EAGLE SIMULATIONS
MATTER
PROJECT
FEEDBACK
HALOES
MODEL
CONSTRAINTS
CONTRACTION
115 Astronomy, Space science
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