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The behaviour of dark matter associated with four bright cluster galaxies in the 10 kpc core of Abell 3827

Massey, R.; Williams, L.; Smit, R.; Swinbank, M.; Kitching, D.; Harvey, D.; Jauzac, M.; Israel, H.; Clowe, D.; Edge, A.; Hilton, M.; Jullo, E.; Leonard, A.; Liesenborgs, J.; Merten, J.; Mohammed, I.; Nagai, D.; Richard, J.; Robertson, A.; Saha, P.; Santana, R.; Stott, J.; Tittley, E.

The behaviour of dark matter associated with four bright cluster galaxies in the 10 kpc core of Abell 3827 Thumbnail


L. Williams

R. Smit

D. Kitching

D. Harvey

H. Israel

D. Clowe

M. Hilton

E. Jullo

A. Leonard

J. Liesenborgs

J. Merten

I. Mohammed

D. Nagai

J. Richard

P. Saha

R. Santana

J. Stott

E. Tittley


Galaxy cluster Abell 3827 hosts the stellar remnants of four almost equally bright elliptical galaxies within a core of radius 10 kpc. Such corrugation of the stellar distribution is very rare, and suggests recent formation by several simultaneous mergers. We map the distribution of associated dark matter, using new Hubble Space Telescope imaging and Very Large Telescope/Multi-Unit Spectroscopic Explorer integral field spectroscopy of a gravitationally lensed system threaded through the cluster core. We find that each of the central galaxies retains a dark matter halo, but that (at least) one of these is spatially offset from its stars. The best-constrained offset is 1.62+0.47−0.49 kpc, where the 68 per cent confidence limit includes both statistical error and systematic biases in mass modelling. Such offsets are not seen in field galaxies, but are predicted during the long infall to a cluster, if dark matter self-interactions generate an extra drag force. With such a small physical separation, it is difficult to definitively rule out astrophysical effects operating exclusively in dense cluster core environments – but if interpreted solely as evidence for self-interacting dark matter, this offset implies a cross-section σDM/m ∼ (1.7 ± 0.7) × 10−4 cm2 g−1 × (tinfall/109 yr)−2, where tinfall is the infall duration.


Massey, R., Williams, L., Smit, R., Swinbank, M., Kitching, D., Harvey, D., …Tittley, E. (2015). The behaviour of dark matter associated with four bright cluster galaxies in the 10 kpc core of Abell 3827. Monthly Notices of the Royal Astronomical Society, 449(4), 3393-3406.

Journal Article Type Article
Acceptance Date Mar 2, 2015
Online Publication Date Apr 9, 2015
Publication Date Jun 1, 2015
Deposit Date Dec 10, 2014
Publicly Available Date Apr 15, 2015
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 449
Issue 4
Pages 3393-3406
Keywords Astroparticle physics, Gravitational lensing, Strong galaxies, Clusters: individual, Abell 3827, Dark matter
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Published Journal Article (5.3 Mb)

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

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