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Published March 10, 2016 | Submitted + Published
Journal Article Open

Frontier Fields Clusters: Deep Chandra Observations of the Complex Merger MACS J1149.6+2223

Abstract

The Hubble Space Telescope Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. We present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z = 0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the line of sight. The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. If the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster.

Additional Information

© 2016 The American Astronomical Society. Received 2015 September 8; accepted 2015 November 25; published 2016 March 4. We thank the referee for constructive comments. G.A.O. acknowledges support by NASA through a Hubble Fellowship grant HST-HF2-51345.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. R.J.v.W. was supported by NASA through the Einstein Postdoctoral grant number PF2-130104 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA, under contract NAS8-03060. R.J.v.W. is supported by a Clay Fellowship awarded by the Harvard-Smithsonian Center for Astrophysics. A.Z. acknowledges support by NASA through a Hubble Fellowship grant HST-HF2-51334.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. This research was performed while T.M. held a National Research Council Research Associate ship Award at the Naval Research Laboratory (NRL). F.A.S. acknowledges support from Chandra grant G03-14131X. Part of this work was performed under the auspices of the U.S. DOE by LLNL under contract DE-AC52-07NA27344. This research made use of NASA's Astrophysics Data System. This research also made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research made use of APLpy, an open-source plotting package for Python hosted at http://aplpy.github.com. Some of the cosmological parameters in this paper were calculated using Ned Wright's cosmology calculator (Wright 2006). The scientific results reported in this article are based on observations made by the Chandra X-ray Observatory. Facility: CXO (ACIS).

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Published - apj_819_2_113.pdf

Submitted - 1603.06010v1.pdf

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Created:
August 22, 2023
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February 24, 2024