Dark matter dynamics in Abell 3827: new data consistent with standard cold dark matter

Richard Massey (1) , David Harvey (2) , Jori Liesenborgs , Johan Richard (3) , Stuart Stach , Mark Swinbank (1) , Peter Taylor (4) , Liliya Williams , Douglas Clowe , Frédéric Courbin (5) , Alastair Edge , Holger Israel (1) , Mathilde Jauzac (1) , Remy Joseph , Eric Jullo (6) , Thomas D. Kitching , Adrienne Leonard (7) , Julian Merten , Daisuke Nagai , James Nightingale , Andrew Robertson , Luis Javier Romualdez , Prasenjit Saha , Renske Smit , Sut Ieng Tam , Eric Tittley

1 ICC - Institute for Computational Cosmology
2 UNSW - School of Mathematics and Statistics [Sydney]
3 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
4 Digital Productivity and Services Flagship: CSIRO, Hobart, TAS
5 EPFL Laboratoire d’astrophysique
6 LAM - Laboratoire d'Astrophysique de Marseille
7 DAP - Département d'Astrophysique (ex SAP)

We present integral field spectroscopy of galaxy cluster Abell 3827, using ALMA and VLT/MUSE. It reveals an unusual configuration of strong gravitational lensing in the cluster core, with at least seven lensed images of a single background spiral galaxy. Lens modelling based on HST imaging had suggested that the dark matter associated with one of the cluster's central galaxies may be offset. The new spectroscopic data enable better subtraction of foreground light, and better identification of multiple background images. The inferred distribution of dark matter is consistent with being centered on the galaxies, as expected by LCDM. Each galaxy's dark matter also appears to be symmetric. Whilst we do not find an offset between mass and light (suggestive of self-interacting dark matter) as previously reported, the numerical simulations that have been performed to calibrate Abell 3827 indicate that offsets and asymmetry are still worth looking for in collisions with particular geometries. Meanwhile, ALMA proves exceptionally useful for strong lens image identifications.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Richard Massey, David Harvey, Jori Liesenborgs, Johan Richard, Stuart Stach, et al.. Dark matter dynamics in Abell 3827: new data consistent with standard cold dark matter. Monthly Notices of the Royal Astronomical Society, 2018, 477 (1), pp.669 - 677. ⟨10.1093/mnras/sty630⟩. ⟨hal-01787782⟩