Jauzac, M. and Jullo, E. and Eckert, D. and Ebeling, H. and Richard, J. and Limousin, M. and Atek, H. and Kneib, J.-P. and Clément, B. and Egami, E. and Harvey, D. and Knowles, K. and Massey, R. and Natarajan, P. and Neichel, B. and Rexroth, M. (2015) 'Hubble Frontier Fields : the geometry and dynamics of the massive galaxy cluster merger MACSJ0416.1−2403.', Monthly notices of the Royal Astronomical Society., 446 (4). pp. 4132-4147.
We use a joint optical/X-ray analysis to constrain the geometry and history of the ongoing merging event in the massive galaxy cluster MACSJ0416.1-2403 (z=0.397). Our investigation of cluster substructure rests primarily on a combined strong- and weak-lensing mass reconstruction based on the deep, high-resolution images obtained for the Hubble Frontier Fields initiative. To reveal the system's dynamics, we complement this lensing analysis with a study of the intra-cluster gas using shallow Chandra data, and a three-dimensional model of the distribution and motions of cluster galaxies derived from over 100 spectroscopic redshifts. The multi-scale grid model obtained from our combined lensing analysis extends the high-precision strong-lensing mass reconstruction recently performed to cluster-centric distances of almost 1 Mpc. Our analysis detects the two well known mass concentrations in the cluster core. A pronounced offset between collisional and collisionless matter is only observed for the SW cluster component, while excellent alignment is found for the NE cluster. Both the lensing analysis and the distribution of cluster light strongly suggest the presence of a third massive structure, almost 2 arcmin SW of the cluster centre. Since no X-ray emission is detected in this region, we conclude that this structure is non-virialised and speculate that it might be part of a large-scale filament almost aligned with our line of sight. Combining all evidence from the distribution of dark and luminous matter, we propose two alternative scenarios for the trajectories of the components of MACSJ0416.1-2403. Upcoming deep X-ray observations that allow the detection of shock fronts, cold cores, and sloshing gas (all key diagnostics for studies of cluster collisions) will allow us to test, and distinguish between these two scenarios.
|Keywords:||Gravitational lensing: strong, Gravitational lensing: weak, Galaxies: clusters: individual, Dark matter, X-rays: galaxies: clusters.|
|Full text:||(VoR) Version of Record|
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|Publisher Web site:||http://dx.doi.org/10.1093/mnras/stu2425|
|Publisher 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.|
|Date accepted:||13 November 2014|
|Date deposited:||17 February 2015|
|Date of first online publication:||09 December 2014|
|Date first made open access:||No date available|
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