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The Extraordinary Amount of Substructure in the Hubble Frontier Fields Cluster Abell 2744

Jauzac, M.; Eckert, D.; Schwinn, J.; Harvey, D.; Baugh, C.M.; Robertson, A.; Bose, S.; Massey, R.; Owers, M.; Ebeling, H.; Shan, H.Y.; Jullo, E.; Kneib, J.-P.; Richard, J.; Atek, H.; Clément, B.; Egami, E.; Israel, H.; Knowles, K.; Limousin, M.; Natarajan, P.; Rexroth, M.; Taylor, P.; Tchernin, C.

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Authors

D. Eckert

J. Schwinn

D. Harvey

A. Robertson

S. Bose

M. Owers

H. Ebeling

H.Y. Shan

E. Jullo

J.-P. Kneib

J. Richard

H. Atek

B. Clément

E. Egami

H. Israel

K. Knowles

M. Limousin

P. Natarajan

M. Rexroth

P. Taylor

C. Tchernin



Abstract

We present a joint optical/X-ray analysis of the massive galaxy cluster Abell 2744 (z=0.308). Our strong- and weak-lensing analysis within the central region of the cluster, i.e., at R < 1 Mpc from the brightest cluster galaxy, reveals eight substructures, including the main core. All of these dark-matter halos are detected with a significance of at least 5σ and feature masses ranging from 0.5 to 1.4× 1014M⊙ within R < 150 kpc. Merten et al. (2011) and Medezinski et al. (2016) substructures are also detected by us. We measure a slightly higher mass for the main core component than reported previously and attribute the discrepancy to the inclusion of our tightly constrained strong-lensing mass model built on Hubble Frontier Fields data. X-ray data obtained by XMM-Newton reveal four remnant cores, one of them a new detection, and three shocks. Unlike Merten et al. (2011), we find all cores to have both dark and luminous counterparts. A comparison with clusters of similar mass in the MXXL simulations yields no objects with as many massive substructures as observed in Abell 2744, confirming that Abell 2744 is an extreme system. We stress that these properties still do not constitute a challenge to ΛCDM, as caveats apply to both the simulation and the observations: for instance, the projected mass measurements from gravitational lensing and the limited resolution of the sub-haloes finders. We discuss implications of Abell 2744 for the plausibility of different dark-matter candidates and, finally, measure a new upper limit on the self-interaction cross-section of dark matter of σDM < 1.28 cm2g−1(68% CL), in good agreement with previous results from Harvey et al. (2015).

Citation

Jauzac, M., Eckert, D., Schwinn, J., Harvey, D., Baugh, C., Robertson, A., …Tchernin, C. (2016). The Extraordinary Amount of Substructure in the Hubble Frontier Fields Cluster Abell 2744. Monthly Notices of the Royal Astronomical Society, 463(4), 3876-3893. https://doi.org/10.1093/mnras/stw2251

Journal Article Type Article
Acceptance Date Sep 5, 2016
Online Publication Date Sep 7, 2016
Publication Date Dec 21, 2016
Deposit Date Sep 28, 2016
Publicly Available Date Oct 6, 2016
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 463
Issue 4
Pages 3876-3893
DOI https://doi.org/10.1093/mnras/stw2251

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Copyright Statement
Advance online version This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.







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