The offsets between galaxies and their dark matter in Λ cold dark matter

Schaller, Matthieu; Robertson, Andrew; Massey, Richard; Bower, Richard G.; Eke, Vincent R.

doi:10.1093/mnrasl/slv104

The offsets between galaxies and their dark matter in Λ cold dark matter

Schaller, Matthieu; Robertson, Andrew; Massey, Richard; Bower, Richard G.; Eke, Vincent R.

Authors

Dr Matthieu Schaller matthieu.schaller@durham.ac.uk
Academic Visitor

Dr Andrew Robertson andrew.robertson@durham.ac.uk
Academic Visitor

Professor Richard Massey r.j.massey@durham.ac.uk
Professor

Richard G. Bower

Dr Vincent Eke v.r.eke@durham.ac.uk
Associate Professor

Abstract

We use the ‘Evolution and Assembly of GaLaxies and their Environments’ (EAGLE) suite of hydrodynamical cosmological simulations to measure offsets between the centres of stellar and dark matter components of galaxies. We find that the vast majority (>95 per cent) of the simulated galaxies display an offset smaller than the gravitational softening length of the simulations (Plummer-equivalent ϵ = 700 pc), both for field galaxies and satellites in clusters and groups. We also find no systematic trailing or leading of the dark matter along a galaxy's direction of motion. The offsets are consistent with being randomly drawn from a Maxwellian distribution with σ ≤ 196 pc. Since astrophysical effects produce no feasible analogues for the 1.62+0.47−0.49 kpc offset recently observed in Abell 3827, the observational result is in tension with the collisionless cold dark matter model assumed in our simulations.

Citation

Schaller, M., Robertson, A., Massey, R., Bower, R. G., & Eke, V. R. (2015). The offsets between galaxies and their dark matter in Λ cold dark matter. Monthly Notices of the Royal Astronomical Society: Letters, 453(1), L58-L62. https://doi.org/10.1093/mnrasl/slv104

Journal Article Type	Article
Acceptance Date	Jul 22, 2015
Publication Date	Oct 1, 2015
Deposit Date	Oct 22, 2015
Publicly Available Date	Nov 5, 2015
Journal	Monthly Notices of the Royal Astronomical Society: Letters
Electronic ISSN	1745-3933
Publisher	Oxford University Press
Peer Reviewed	Peer Reviewed
Volume	453
Issue	1
Pages	L58-L62
DOI	https://doi.org/10.1093/mnrasl/slv104
Keywords	Astroparticle physics, Cosmology: theory, Dark matter.
Related Public URLs	http://arxiv.org/abs/1505.05470

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society: letters. ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.