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The core of the massive cluster merger MACS J0417.5-1154 as seen by VLT/MUSE

Jauzac, Mathilde; Mahler, Guillaume; Edge, Alastair C; Sharon, Keren; Gillman, Steven; Ebeling, Harald; Harvey, David; Richard, Johan; Hamer, Stephen L; Fumagalli, Michele; Swinbank, A Mark; Kneib, Jean-Paul; Massey, Richard; Salomé, Philippe

The core of the massive cluster merger MACS J0417.5-1154 as seen by VLT/MUSE Thumbnail


Guillaume Mahler

Keren Sharon

Steven Gillman

Harald Ebeling

David Harvey

Johan Richard

Stephen L Hamer

A Mark Swinbank

Jean-Paul Kneib

Philippe Salomé


We present a multiwavelength analysis of the core of the massive galaxy cluster MACS J0417.5−1154 (⁠z = 0.441). Our analysis takes advantage of Very Large Telescope/Multi-Unit Spectroscopic Explorer observations which allow the spectroscopic confirmation of three strongly lensed systems. System #1, nicknamed The Doughnut, consists of three images of a complex ring galaxy at z = 0.8718 and a fourth, partial and radial image close to the brightest cluster galaxy (BCG) only discernible thanks to its strong [O II] line emission. The best-fitting mass model (rms of 0.38 arcsec) yields a two-dimensional enclosed mass of M(R<200kpc)=(1.77±0.03)×1014M⊙ and almost perfect alignment between the peaks of the BCG light and the dark matter of (0.5 ± 0.5) arcsec. We observe a significant misalignment when system #1 radial image is omitted. The result serves as an important caveat for studies of BCG–dark-matter offsets in galaxy clusters. Using Chandra to map the intracluster gas, we observe an offset between gas and dark matter of (1.7 ± 0.5) arcsec, and excellent alignment of the X-ray peak with the location of optical emission line associated with the BCG. We interpret all observational evidences in the framework of ongoing cluster merger activity, noting specifically that the coincidence between the gas and optical line peaks may be evidence of dense, cold gas cooled directly from the intracluster gas. Finally, we measure the surface area, σμ, above a given magnification factor μ, a metric to estimate the lensing power of a lens, σ(μ > 3) = 0.22 arcmin2, which confirms MACS J0417 as an efficient gravitational lens.


Jauzac, M., Mahler, G., Edge, A. C., Sharon, K., Gillman, S., Ebeling, H., …Salomé, P. (2018). The core of the massive cluster merger MACS J0417.5-1154 as seen by VLT/MUSE. Monthly Notices of the Royal Astronomical Society, 483(3), 3082-3097.

Journal Article Type Article
Acceptance Date Nov 30, 2018
Online Publication Date Dec 7, 2018
Publication Date Dec 7, 2018
Deposit Date Dec 18, 2018
Publicly Available Date Jan 8, 2019
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 483
Issue 3
Pages 3082-3097


Published Journal Article (19.8 Mb)

Copyright Statement
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society

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